MANUFACTURING HEAT TREAT TECH

Heat Treat Radio #128: Silicon Carbide Without Transformers: How Is That Possible?

/ CONTROLS TECHNICAL CONTENT, HEAT TREAT RADIO, MANUFACTURING HEAT TREAT TECH

In this episode of Heat Treat Radio, Tony Busch of Control Concepts, Christina Clowes of I Squared R, and Dr. Stephen Feldbauer of Abbott Furnace Company join host Doug Glenn to discuss a new transformer-free approach to electrically heated furnaces. The group walks through how SCR power controllers paired directly with silicon carbide heating elements can reduce system cost, simplify design, and improve control accuracy. They also explore the global adoption of zero-cross technology and its growing relevance in North America.

Below, you can watch the video, listen to the podcast by clicking on the audio play button, or read an edited transcript.

The following transcript has been edited for your reading enjoyment.

Introduction (0:45)

Doug Glenn: We’re going to be talking about a relatively new combination of two fairly well-known technologies that will help some people save money. Those two technologies are SCR power controllers and silicon carbide heating elements. It’s actually kind of a little case study. If you’ve got an electrically heated furnace, this would be one you’ll want to stay and hear.

Clockwise from top left: Doug Glenn (host), Christina Clowes of I²R Elements Company, Tony Busch of Control Concepts, and Dr. Stephen Feldbauer of Abbott Furnace Company

Our first guest is Tony Busch from Control Concepts. Tony Busch is the North American sales manager for Control Concepts. Next is Christina Clowes, the vice president over at I²R Elements Company. Our final guest is Dr. Stephen Feldbauer, the director of research and development at Abbott Furnace Company.

A Furnace with a New Configuration (1:45)

Doug Glenn: To get a sense of this furnace that we’re talking about, can you describe the situation and this new configuration of power controls for the heating elements?

Steve Feldbauer: What I can say is that this was a new piece of equipment to replace an old technology for a new facility.

Okay, so they were going to move to a new facility and they said, “Hey, we don’t want this old stuff. Let’s look at just buying a new furnace for this application.”

This is for the casting industry. The molds go into the furnace and traverse through; the furnace preheats them so that operators can then pull them out and fill them with metal. So it’s a continuous furnace for mold preheating application for the casting industry.

It was exciting! We had an electrically heated furnace, and then began talking with Tony and Christina. Control Concepts had this concept, no pun intended: Traditionally, design of an electrically heated furnace above a certain temperature (1850 degrees), we use silicon carbide heating elements and — due to resistance changes over time — we have to put transformers in there that allow us to keep upping the voltage and maintain heating capability. Control Concepts said, “Hey, we can take innovate technology and save some money, make things a little easier, and get rid of the transformers.”

And we really had a great outcome.

Doug Glenn: This is a foundry industry application, the preheating of molds, and this is a continuous furnace. You guys, Abbott, obviously won that bid to supply that furnace. I’m sure it was a competitive situation, so congratulations.

Traditional SCR and Silicon Carbide Heating Element Configuration (4:40)

Doug Glenn: So Tony, one of the great features of this Abbott furnace that helped them win this order was this relatively new configuration of the power supplies. as Steve was saying. Tell us a little bit more about the SCRs and the silicon carbide heating elements.

Tony Busch: I think it’s important to understand where we came from and where we are now with this new technology.

In the past, at least in North America, silicon carbide heating elements produce a high temperature, a high current. To help that happen and so you do not have a big, thick gauge wires, a transformer would be added to the design very close to the furnace. This reduces the conductor size. That transformer often was a multi-tap transformer. From a SCR power controller standpoint, you would be controlling the power on the primary side of the transformer, let’s say 480 volt stepping down into 60-70, whatever volts are required for the application. To use a transformer with a power controller, you need phase angle power control.

This is how it has been done in the past with phase angle firing varying every half cycle into the primary of a transformer.

The New Setup (06:09)

Example of SCR power controller units attached directly to industrial furnace. Source: Control Concepts

Doug Glenn: What is the new configuration?

Tony Busch: With the new scheme, we are removing the transformer. Now you have an SCR power controller firing directly into the silicon carbide heating elements.

To do this, you will have to have slightly bigger power controllers, but you’re completely eliminating the transformer and you’re going directly into it. To take it a step further, we use a special firing mode called Fast Zero Cross. This mode satisfies the heating elements.

We are maintaining a very smooth watt density output to the heating elements. You can control it and the power feedback if you need to, which is essentially your unit of measure to control the power, which can be in KW versus voltage or current.

Doug Glenn: That’s on the power side. Control side of things. That’s basically the new arrangement: removal of the transformer; direct feed into the heating element, with some advantages. Christina, how about the heating element? Can you tell us a little bit about the heating element in this situation?

Christina Clowes: This is not a unique heating element in this particular case, because the same heating element configuration probably would’ve been used even if you were using a multi-tap transformer based system.

The key to the operation here is the very rapid switching of full sine waves through the heating elements, where you’re proportioning the “on-to-off” cycles, electrical cycles, so rapidly that the heating element does not have time to respond to the very high instantaneous loadings during each “on” cycle.

For example, in the U.S., typically you are looking at a power supply that’s at 60 hertz, 60 cycles per second. One electrical cycle is one 60th per second, or 16.66 milliseconds. In that case, if you were regulating the outputs from the heating elements to 50%, you would have one cycle on, followed by one cycle off, and that being repeated continually.

The heating element during that one cycle, that 16.66 milliseconds, does not have enough time to respond firmly to that very high loading. As a result, the RMS voltage, the natural average voltage over time, governs the load into the heating elements. So, you can design around systems based on 480 volts but regulate the RMS output on the controller to whatever the heating element needs to generate the amount of power that’s needed by the process.

The control is the key to this operation.

Doug Glenn: Is it possible to use a standard or any type of heating element or do you need a special silicon carbide type?

Christina Clowes: It is not a special silicon carbide. We designed this particular application around the needs of the process, the operating temperature, the specific loading required for the process. But it is a different control methodology that’s really the key.

New Technology for North American (10:22)

Doug Glenn: While this technology is somewhat new in North America, it is actually not new on a global context. Can you address this?

Christina Clowes: In Europe, this kind of zero-cross base system has been commonplace for quite some years; also in Asia. The difference in North America is, I think, tradition, more than anything else. People have been used to using phase angle control for silicon carbide heating elements. That’s kind of where this technology grew out from, and people have stuck with that because it works. But this new technology though gives an opportunity to save money and space, while achieving the same result.

Doug Glenn: So for the North American market, this is somewhat new. But it is a proven technology. It’s not a new technology that we are still trying to get our hands around. It’s been done globally, which is an important point.

Cost Savings for the Customer (11:45)

Doug Glenn: With respect to cost savings for the customer, can you describe the capital expenditures, operating costs, and even maintenance costs?

Steve Feldbauer: We know that by eliminating the transformer, there’s the substantial costings. The SCR is doing the change in the voltage and controlling and eliminating that need for the transformer.

By eliminating that piece of equipment, you’re seeing upwards of anywhere between a 50 to 75% cost savings per heating zone. That’s a big number. There’s a wide range in that cost savings depending on the size of the heating zone, the size of the furnace, and the number of heating zones. That is a substantial saving.

In addition, the customer sees savings in shipping costs. In this case, removing the transformer reduced the size of the furnace by 2,100 pounds. That goes directly into your shipping cost.

Customers also see a lot less downtime because every time that you would want to change the tap in a traditional furnace, you have to power the furnace down, which interrupts production. There’s a knowledge base needed to know when and how to change the tap. But with this new technology, the furnace just continually operates.

There is also space savings. That transformer takes up space, which limits where we can put in things. For example, for the last line on a continuous furnace with a belt, the placement of the belt is dictated by where we put the transformers because the transformers typically go up underneath the hot box. Without the transformer, we now have flexibility and design.

So, we save in a number of different areas.

Maintenance of the SCR (14:24)

Doug Glenn: Maintenance wise, are the SCRs easier to maintain?

Steve Feldbauer: There is not much maintenance required for the SCRs. Once you put them in and they are set up, our customers really do not have to touch them unless they have to replace them. As far as tuning them and similar maintenance, there’s really not a lot that goes into them. Especially since now, you’re also not changing voltages. There’s not a lot of variability in the system. It’s set up and it just sits there and controls itself.

Advantages for the Customer (17:45)

Doug Glenn: What are the advantages for the customer?

Steve Feldbauer: There are many advantages in terms of cost, maintenance, and the ease in usage. There’s also less training, because you’re not teaching someone when or how to change a tap. This is a marked change in how you look at electrical furnace control in North America. This is something that is widely used throughout the rest of the world, so it’s not a new technology, but it’s new and innovative to North America. If you can optimize and streamline the process, why wouldn’t you?

Upgraded Features: Digitization and Data (18:58)

Doug Glenn: I also understand there are upgraded features because you’ve moved to an SCR and into a digital world with being able to get data back out of the furnace and understand the operation of the system because of the digitalization of it. Do you want to address that?

Tony Busch: By having a digital SCR power controller, you can connect up to your network, whether it’s Ethernet IP or Modbus TCP. You are able to collect all of that data. From that data, you are able to do things such as monitor the KW per hour. If you’re starting your process, and you want to know how much power was consumed during that particular time period, you can reset your KW per hour. Then you can find out how much you consumed when you are done and evaluate your efficiencies. All of that is recorded within the power controller. It’s essentially an industrial grade power meter built in.

Also, now that you are directly coupled with the silicon carbide heating elements, you have a very accurate load resistance monitoring capability. You are able to analyze the resistance and determine the health of your silicon carbide heating elements.

You can also plot a resistance curve. So you would know that if tolerance drifts 10, 20, 30%, you may be looking at a predictive maintenance situation where you look at your heating elements at some point and monitor the load currents. For a three-phase setup, if you notice that one of the phases is unbalanced, you may want to evaluate and determine the cause. You are able to be alerted without manually getting in there with a multimeter and doing your own research.

Christina Clowes: Compared to phase angle firing, which has been historically the most commonly used in North America, switching to a zero-cross system, a full sine wave based system, the SCRs turn on and off at zero volts potential.

To learn more about how SCR power controllers support tighter control when directly coupled with heating elements, you can click the image above to read this in-depth technical article co-written by Tony Busch.

As a result, that doesn’t produce any transient spikes that create a harmonic overlay, so there’s no electrical noise being generated. Utility companies do penalize their customers for generating electrical noise on their supplies.

In addition, because you have false sine waves, you have unity power factor, essentially. There’s no poor apparent power factor, which you have with a phase angle firing because you’re chopping the sine wave and conducting only part of the sine wave.

When you have purely resistive load, in the case of a Star Bar element, there’s no reactance, inductance, or capacitance. But because of the way that a phase angle SCR fires, it appears that there’s a power factor and people pay for energy that they are not consuming. This is more efficient way of driving an element system with a better handle over the energy that you’re consuming.

Doug Glenn: Is it more difficult to engineer these systems?

Christina Clowes: The exciting or interesting part is introducing new technology to people that actually helps them and provides real benefits. The total cost of the system is simplified and reduced, which makes it far more attractive for Star Bar-based systems to be sold into applications.

Doug Glenn: Right, right. Okay. Tony, how about you? What was interesting and challenging?

Tony Busch: Sure, yes. Christina touched on it a little bit. It would be that power factor in harmonics — being able to show the ability and not be penalized from your utilities for power factor and potential harmonics. Those questions come up, you know, pretty much anytime you’re using an electric furnace and SCR power controllers, but it’s much more easy to demonstrate to customers that you’re not going to see any of those issues. And I’ve seen our electric bill. When you’re running phase angle, you get these big old penalties that come up on there. It’s nice to be to pass that savings onto the customers with this new application.

Doug Glenn: Yeah. Yeah, that’s interesting. And Steve, I saved you for last because you were the ones that really had to interface with the customer. What was interesting or challenging for you guys?

Steve Feldbauer: I’ll tell you what, it was exciting for us to be able to provide new technology — new to North America — that number one makes it simpler for the customer to use.

You know, one of the challenges is always trying to teach people, “when do I need to change a tap or is there really some other problem?” Well, this eliminates that. Now we’re helping them to be able to operate the furnace more efficiently. And, you know, they don’t require all of the training.

We’re also able to pass on some cost savings because we aren’t buying that transformer. We’re able to have some leeway internally for design and construction. So all the way around, it’s a win-win, right? For the customer, for us, and for the industry, in general. Because now we’re able to move the heating technology forward.

Sustainability Benefits of the SCR Power Controller (26:31)

Doug Glenn: Yeah. I probably should have asked this question before, but there’s always a lot of talk about sustainability and greenness. Are there advantages here on this system?

Steve Feldbauer: Tony, you want to talk about it? I’m sure you can address the harmonics and different things that actually help out.

Tony Busch: Most definitely. From a power controller standpoint, the efficiency is right around 99.9%; you’re not really getting any losses through the power controller. And now you’re talking about being full wave firing, so you’re not trimming back that sine wave, you’re eliminating all those other harmonics. You should see a benefit from all of your equipment, if they ever experience that as well as, and your utility bill, not seeing that power factor.

Doug Glenn: Yeah. So basically I guess that’s it. The simple answer is if you’re reducing your energy bill, then obviously we’re using less energy and that’s probably less of a carbon footprint depending on where your electricity’s coming from. Well guys, thanks very much. This is a very interesting, great partnership between the three companies, obviously for the benefit of customers. Appreciate you working for the benefit of a customer and for spending a little bit of time with us here today.

About the Guests

Tony Busch
North American Sales Manager
Control Concept

Tony Busch is Control Concept’s North American Sales Manager. Currently in his 15th year with Control Concepts, he has experience in assembly, testing, troubleshooting, field service and an expert understanding of application engineering of SCR power controllers. Tony has a bachelor’s degree in electrical construction from Dunwoody College of Technology which he now applies the electrical concepts to power controllers and their related applications.

For more information: Contact Tony at tony.busch@ccipower.com.

Christina Clowes
Corporate Vice President and Director
I Squared R Elements Co., Inc.

Christina Clowes is the Corporate Vice President and a Director of I Squared R Elements Co., Inc., located in Akron, NY. She has been at I Squared R for the past 9 years and a little over 40 years in the thermal processing industry, focusing on new product and application development.

For more information: Contact Christina at christina.clowes@isquaredrelement.com.

Dr. Stephen Feldbauer
Director of Research and Development
Abbott Furnace Company

Dr. Stephen Feldbauer received his Ph.D. in 1995 from Carnegie Mellon University in Materials Science and Engineering. He joined Abbott Furnace Company in 2002 where he is currently the Director of Research and Development. Dr. Feldbauer is also a Senior Adjunct Faculty member in Engineering at the Pennsylvania State University. He is the author of numerous articles, publications, and has been awarded eight patents in both the USA and Europe. He is an active member of the MPIF, the American Welding Society’s C3 Committee on Brazing, and a co-chair of the Markets committee of NAATBatt International.

For more information: Contact Stephen at sfeldbauer@abbottfurnace.com.

Heat Treat Radio #128: Silicon Carbide Without Transformers: How Is That Possible? Read More »

Pit LPC: A Modern Take on High Throughput Heat Treat

/ CARBURIZING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, VACUUM FURNACES TECHNICAL CONTENT

Producing durable, wear-resistant gears for the wind turbine industry requires exacting control of carbon diffusion. Modern low pressure carburizing (LPC) is pushing the boundaries of control and consistency. This technology fine tunes carbon diffusion into the surface of components, and applied in a new pit-style vacuum furnace, it also delivers temperature uniformity, stronger gears, and shorter cycle times for large, complex components, all while eliminating oxidation and direct CO₂ emissions. In this Technical Tuesday installment, Tom Hart, director of sales for North America at SECO/WARWICK Corporation, examines how modern LPC technology in a pit-style vacuum furnace is reshaping high-volume carburizing for today’s in-house heat treaters.

This informative piece was first released in Heat Treat Today’s November 2025 Annual Vacuum Heat Treating print edition.

The Need To Carburize

Carburizing is a thermochemical treatment that finds applications across the automotive, aviation, and energy industries, particularly in power transmission systems. The widespread use of this process across many industries stems from its ability to improve mechanical properties by enriching the surface of steel with carbon.

Consider the wind turbine industry, growing with a CAGR (compound annual growth rate) of 6.2% from 2024 to 2033 (GlobeNewswire 2024). Carburizing plays a key role in the production of gears and pinions. These components, often made of alloy steels, such as 18CrNiMo7-6, 4320, 4820, and 9310 (GearSolutions 2009, Jantara 2019), must meet high strength and quality requirements. Carburized layers, often over 4 mm thick, provide resistance to wear and dynamic loads, which is important given the turbine’s expected service life of at least twenty years.

In practice, however, gears often require servicing after five to seven years (Jantara 2019), with their failures generating long downtimes and high costs (Perumal and Rajamani 2014).

Figure 1a: Pit-LPC in a hardening cell (model)
Figure 1b: The view from the operator platform

The carburizing process, combined with hardening (usually in oil) and tempering, increases:

  • Surface hardness: improving abrasian resistance
  • Core ductility: protecting against cracks
  • Fatigue strength: extending the life of the part, which translates into lower operating costs

Alternative technologies, such as nitriding or surface hardening, offer other benefits (e.g., reduced deformation), but have limitations, such as thinner hardened layers, relatively long nitriding process times, or difficulties with complex geometry for surface hardening.

Pit Meets Vacuum LPC

Traditional atmospheric carburizing, despite its established position, has reached its limits in process performance expectations. In response to market needs, LPC (low pressure carburizing) technology is being increasingly implemented to enable precise process control, reduced emissions, and improved energy efficiency. More specifically, a pit furnace with vacuum heat treatment capabilities, aka the Pit-LPC, has been designed and developed to carburize thick layers on very large and/or long parts. This furnace combines the advantages of LPC technology with the ability to integrate existing hardening cells, facilitating the modernization of older installations.

While a vacuum furnace opening to an air atmosphere is a feature previously reserved for atmospheric furnaces, this innovative pit furnace has ceramic insulation and a dedicated heating system to leverage this capability. The chamber door can therefore be opened at process temperature in an air atmosphere for the direct transfer of the charge to the hardening tank. Additionally, the furnace is equipped with a closed circuit forced cooling system, which significantly shortens the charge cooling time from the carburizing temperature to the hardening temperature, increasing efficiency and shortening the production cycle.

Furthermore, the furnace allows for the process to be carried out at temperatures of 1925°F (1050°C) and higher, significantly shortening carburizing time and reducing production costs, even while maintaining a safe level of grain growth (e.g., 1800°F (980°C)).

Benefits of LPC technology designed in a pit furnace include:

  • Reduced process time due to higher operating temperatures
  • Elimination of internal oxidation (IGO) in the carburizing process
  • Highly uniform carburized layer
  • Low process gas consumption
  • No direct CO₂ emissions and fire risk
  • Ready for operation without lengthy conditioning
  • Computer-aided process support

Additionally, the furnace design increases work safety and comfort in its elimination of open flames, risks of explosion, and the need for constant atmospheric monitoring.

Figure 2. SimVac program window with an example LPC process simulation

This new pit furnace is compatible with SimVac software, developed by Lodz University of Technology and SECO/WARWICK, which enables the simulation and optimization of LPC parameters, reducing the need for process tests. SimVac Plus is a simulation software that includes a vacuum carburizing module (Figure 2). The program can be used either as a standalone tool for designing processes based on the desired carburized layer requirements or to visualize the effect of a given boost/diffusion sequence in the form of a carbon profile.

Testing the Furnace Characteristics and Technical Parameters

The furnace was designed to meet the highest requirements for heat treatment equipment. The basic technical parameters are as follows:

  • Working space / charge weight: 71″ diameter x 118″ deep / 17,600 lb (1,800 mm x 3,000mm deep / 8,000 kg)
  • Operating temperature: up to 2010°F (1100°C)
  • Heating power: 360 kW, three independent zones
  • Vacuum level: 10⁻² torr
  • Carburizing gas: acetylene

Temperature Uniformity

Temperature distribution tests were conducted in the furnace, with 12 load thermocouples arranged according to the diagram shown in Figure 2. Measurements were taken at several temperatures under vacuum conditions. The purpose of the tests was to confirm compliance with the Class 1 ±5°F (3°C) requirements of the AMS2750 standard.

Figures 3a-d. Location of the TUS load thermocouples and the results in vacuum at temperatures of 1550°F (840°C), 1800 °F (980°C), and 1925°F (1050°C)

The results presented in Figure 3 indicate that the furnace provides above-average temperature uniformity, which is particularly important for a large workspace with 71″ diameter x 118″ deep (1,800 mm diameter × 3,000 mm deep) and the processing of large-sized components with thick layers. The temperature difference (ΔT) between the extreme thermocouples, measured at 1550°F (840°C), 1800 °F (980°C), and 1925°F (1050°C), did not exceed 3.5°F (2°C). This means that the furnace meets the Class 1 requirements of the AMS2750 standard by a wide margin.

Operational Dynamics

Additionally, to evaluate the furnace’s operational dynamics, heating and cooling tests were performed on an empty device with samples. Figure 4a shows the heating curve; the furnace reaches a temperature of 1800°F (980°C) in 60 minutes. The furnace’s high energy efficiency has a heat loss of just 32 kW under these circumstances.

Figure 4a. Heating Rate
Figure 4b. Cooling Rate

Figure 4b shows teh curve of cooling forced by nitrogen at atmospheric pressure, measured in three zones and on samples with diameters of 1″ (25 mm) and 4″ (100 mm). The temperature drops from 1800°F (980°C) to 575°F (300°C) in 60 minutes; reaching 210°F (100°C) takes only two hours, whereas natural cooling would take several days.

Vacuum tests show that the furnace reaches operating vacuum of 10⁻¹ hPa in under 30 minutes and has a leakage rate of 10⁻³ mbar·l/s, which meets the industry standard for vacuum furnaces.

Test of Atmosphere vs. Vacuum Carburizing Processes

To obtain a carburized layer 0.145–0.160″ (3.7–4.0 mm) thick for 52.3 HRC (550HV1), two tests were compared: one in the PEGAT atmosphere furnace (Figure 5a) and another in the Pit-LPC vacuum furnace (Figure 5b). In both cases, the charge consisted of seven gears made of 18CrNiMo7-6 material, with a total weight of approximately 6.5 tons and a surface area of 280 ft² (26 m²). The process consisted of three stages:

  • Stage I: heating to the carburizing temperature and soaking
  • Stage II: actual carburizing with cooling to the hardening temperature and holding
  • Stage III: hardening in an external quenching tank — identical in both processes
Table A. Atmosphere vs. Vacuum Carburizing Process Comparison
Figure 5a. Essential process data and schematic flow of the carburizing process in a PEGAT atmosphere furnace
Figure 5b. Essential process data and schematic flow of the carburizing process in the Pit-LPC vacuum furnace

The LPC process, which consists of saturation and diffusion segments (Figure 6) allows for the precise control of carbon distribution. As the process progresses, the duration of the diffusion segments is extended, ensuring uniform saturation of the material.

Figure 6. Vacuum carburizing process trends in the Pit-LPC

After carburizing and hardening, all components were tempered at 355°F (180°C) for three hours.

Metallurgical Results: Gears & Samples Destructive Testing

Table B. Chemical Composition of 18CrNiMo7-6 (according to EN10084)

Gears and samples made of 18CrNiMo7-6 steel were used for destructive testing, in accordance with the EN 10084 standard. Six cylindrical samples were placed throughout the workspace — inside and outside the part — to assess carburization uniformity.

Tests conducted:

  • Vickers microhardness (HV1): performed on a Struers Durascan 70 device, allowing for the determination of hardness profiles and carburized layer depth (ECD) — a load of 9.81 N (HV1).
  • Surface and core hardness (Rockwell): measurements were performed on a Wilson Wolpert TESTOR tester with a load of 1470.1 N. At least five measurements were taken for each sample.
  • Microstructure: assessed on a Nikon LV150 optical microscope after nital etching.
  • Internal oxidation (IGO): analyzed on the unetched surface of the microsection.
Figures 7a-f. Microhardness profiles after the full process (carburizing, hardening, and tempering)

Figure 7 shows the microhardness profiles for the tested samples. For each sample, microhardness paths were inspected in three cross-sections. Based on this, the effective ECD layer thickness obtained on each sample was determined, as presented in Table C.

Table C. Thickness of the Carburized Layer Read from the Microhardness Charts (effective case depth average is 0.145–0.160″ (3.7–4.0 mm) at 52.3 HRC (550 HV1))

Average ECD values obtained for the samples ranged from 0.148 to 0.154″ (3.77 to 3.91 mm).

Surface and core hardness values for all samples were consistent and typical of carburized layers (Table D). Surface hardness ranged from 61.0 to 63.2 HRC and core hardness from 39.9 to 40.7 HRC. Interestingly, samples located on the inner side of the wheel achieved slightly higher surface hardness values (caused by retained austenite and cooling intensity).

Table D. Measured values of surface hardness and core hardness

Microstructure images of low-tempered martensite, along with retained austenite, were identified, ranging from 17 to 20% (Figure 8). The amount of retained austenite was determined using NIS-Elements software. No variation in structure was observed depending on sample location.

Figure 8a. Exemplary post-processing microstructure pictures of sample 1 surface. Magnifications x100 (left) and x500 (right). Nital etching 2%. Martensite with residual austenite (approx. 18%).
Figure 8b. Exemplary post-processing microstructure pictures of sample 4 surface. Magnifications x100 (left) and x500 (right). Nital etching 2%. Martensite with residual austenite (approx. 20%).

The presence of intergranular oxidation (IGO) was also inspected, averaging 5.5 μm throughout the tested samples. For comparison, intergranular oxidation in the atmospheric process averages above 15 μm. In the new LPC pit furnace, internal oxidation only occurs during unloading and transfer of the charge to the hardening tank, whereas in the atmospheric furnace, the presence of oxygen in the carburizing atmosphere is also significant, significantly increasing the IGO value.

The level of hardening deformation after the process conducted in the new LPC pit furnace and the atmosphere furnace is comparable due to the use of the same hardening tank in both devices and the absence of the carburizing process.

Comparison of Process Economics

Economic aspects play a key role in modern heat and thermochemical processing. Therefore, the consumption of basic utilities was compared for the reference processes (described in Chapter 5), resulting in a 0.152″ (3.8 mm) thick hardened layer. The analysis included a Pit-LPC and a PEGAT-type atmospheric furnace, both with identical workspace and the same charge. In addition, the LPC process was simulated at 1900°F (1040°C). The results are summarized in Table E.

Table E. Comparison of utility consumption and costs

The results show that the new LPC furnace model consumes significantly less electricity by approximately 57%, which translates into a lower carbon footprint, especially when energy is derived from fossil fuels. Nitrogen consumption is comparable, with a slight advantage for the Pit-LPC (savings of up to 10%).

The largest differences are found in carburizing gases. The atmospheric furnace consumes 9,900 ft³ (280 m³) of methane — approximately 440 lb (200 kg) and an additional 4.4–13.2 lb (2–6 kg) of propane per process. In the LPC furnace, acetylene consumption is reduced to 39.2 lb (17.8 kg) because carburizing gas only flows during the boost phase.

Importantly, the LPC process does not generate direct CO₂ emissions, unlike an atmospheric furnace, which emits approximately 1325 lb (600 kg) of CO₂ per cycle. Cooling water consumption in the new LPC furnace is also reduced by over 45%.

The presented comparison of utility consumption in the two types of furnaces directly translates into the economic aspects of using these devices and conducting production processes. For cost comparison purposes, the following unit utility costs were assumed, as presented in Table F:

Table F. Unit costs of energy factors and technological gases according to European averages

In summary, the total utility costs for the process conducted in the Pit-LPC at 1800°F (980°C) are 53% lower compared to an atmospheric furnace conducted at 1700°F (925°C). At a temperature of 1925°F (1040°C), savings reach 60%. These savings are primarily due to lower energy and process gas consumption. Furthermore, the lack of CO₂ emissions eliminates the need to pay emission fees.

The efficiency of this furnace is almost twice as much at 1795°F (980°C) and three times as much at 1925°F (1040°C) compared to an atmospheric furnace.

Summary

The new Pit-LPC vacuum furnace combines the design features of a top-loaded pit and performs carburizing using vacuum technology instead of atmospheric technology. Bringing higher processing temperatures than traditional atmospheric furnaces to the market, as well as the ability to open hot in an air atmosphere, this technology proves that direct transfer of the charge to the hardening tank is possible in vacuum furnaces.

Another key development, this design significantly shortens carburizing time compared to atmosphere furnaces since the furnace can operate under vacuum, inert gas (nitrogen, argon), air, and carburizing gases, at temperatures up to 2010°F (1100°C).

Since this new pit furnace design does not require the use a retort or atmosphere mixer, which are the most vulnerable components inside a traditional atmospheric furnace, the furnace operates with greater reliability and lower costs. Furthermore, an efficient and robust vacuum pumping system provides the vacuum environment and operational readiness in less than 30 minutes. Time is also saved by the integrated closed-loop gas cooling system that shortens cooling time: dropping temperatures from 1800°F (980°C) to 1545°F (840°C) in 30 minutes for a full charge and to 210°F (100°C) in two hours for an empty furnace, operations which would take several hours and days respectively in atmosphere furnaces.

The advanced thermal insulation and a uniform heating element layout ensure high energy efficiency and precise temperature uniformity in the working space, yielding additional cost and energy savings.

This carburizing process is based on FineCarb LPC technology and supported by the SimVac simulator, enabling precise carbon profile shaping and achieving layers 0.148–0.154″ (3.77–3.91 mm) thick with high repeatability.

With the ability to operate at temperatures up to 1925°F (1050°C), the new LPC pit-styled furnace significantly shortens process time, reduces utility consumption, and lowers operating costs by up to 50%, while increasing productivity by a factor of x2 to x3. One of these furnaces can replace two to three atmosphere furnaces of the same size.

Finally, the furnace operates in a safe and non-flammable atmosphere, emits no direct CO₂, and reduces energy consumption, making it an environmentally friendly solution.

Conclusions

The Pit-LPC furnace is a modern alternative to the traditional atmosphere furnace and offers a number of advantages in terms of quality, efficiency, safety, economy, and ecology. Providing an innovative solution for vacuum carburizing and meeting stringent carburization layer thickness guidelines, this design is a viable option to fully replace traditional atmospheric pit furnaces operating in a carburizing atmosphere.

References

GlobeNewswire. 2024. “Wind Turbine Market to Reach $115.2 Billion Globally by 2033 at 6.2% CAGR: Allied Market Research.” GlobeNewswire, September 18, 2024. https://www.globenewswire.com/news-release/2024/09/18/2948365/0/en/Wind-Turbine-Market-to-Reach-115-2-Billion-Globally-by-2033-at-6-2-CAGR-Allied-Market-Research.html

GearSolutions. 2009. “Carburizing Wind-Turbine Gears.” Gear Solutions, May 1, 2009. https://gearsolutions.com/features/carburizing-wind-turbine-gears/

Jantara, Valter Luiz Jr. 2019. “Wind Turbine Gearboxes: Failures, Surface Treatments and Condition Monitoring.” In Non-Destructive Testing and Condition Monitoring Techniques for Renewable Energy Industrial Assets, edited by Mayorkinos Papaelias, Fausto Pedro García Márquez, and Alexander Karyotakis. Amsterdam: Elsevier.

Perumal, S., and G. P. Rajamani. 2014. “Improving the Hardness of a Wind Turbine Gear Surface by Nitriding Process.” Applied Mechanics and Materials 591: 19–22.

Rolinski, Edward. 2016. “Modern Nitriding Techniques for Gear Applications.” Gear Solutions, March 16, 2016. https://gearsolutions.com/departments/hot-seat-modern-nitriding-techniques-for-gear-applications/

About The Author:

Tom Hart
Director of Sales for North America
SECO/WARWICK Corporation

Tom Hart joined SECO/WARWICK in 2011 as a sales engineer and has been in the precision manufacturing industry for over 16 years. His responsibilities have him caring for SECO/WARWICK’s clients and their various process and heat treatment equipment needs. Tom received his manufacturing engineering degree from Edinboro University of Pennsylvania, has authored numerous white papers, and is recognized throughout the heat treatment industry as a go-to-guy for thermal processing.

For more information: Contact Tom at Tom.Hart@SecoWarwick.com.

Pit LPC: A Modern Take on High Throughput Heat Treat Read More »

Flame and Fire: History of the Industrial Gas Industry

/ BURNERS & COMBUSTION SYSTEMS TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, OP-ED

Jim Roberts of U.S. Ignition entertains readers in a Combustion Corner editorial about how the industrial gas industry evolved from its humble beginnings in the early 1900s into a precision-driven force that transformed combustion technology and modern manufacturing.

This editorial was first released in Heat Treat Today’s November 2025 Annual Vacuum Heat Treating print edition.

Let’s think about how young the industrial gas industry really is.

A Short Pipeline in Time

The first real industrial usage was way back in the 1800s somewhere. But there was no infrastructure, no supply other than bottled gas for industrial applications. The gas industry, as far as we recognize it, did not really take off until somewhere around the early 1920s when the first welded pipeline was installed. Then, as usage increased, it became apparent that safety was going to be a concern. The addition of mercaptan (rotten egg smell) was not until the late 1930s.

With the growth of commercial and residential usage, the demand for gaseous fuels grew by 50 times the original market size anticipated between 1910 and 1970! What does that demand look like? Today there are over 3 million miles of gas distribution lines connected to 300,000 miles of big transmission pipelines in the U.S. alone. All that growth in a span of 100 years, essentially. That means the transmission pipeline system in the U.S. could stretch around the planet 12 times!

USS coke gas pipeline in the foreground with the Conrail Port Perry Bridge spanning the Monongahela River, Port Perry, Allegheny County, PA (Lowe, 1994)
Source: Library of Congress Prints and Photographs Division

Most of that construction occurred during the post-war 1940s to 1960s timeline. That’s one busy industry! And it dragged all the thermally based markets and industries along with it. Now, we have come to accept the availability of natural gas as so commonplace that we cannot imagine life without it.

Responding with Precision

So, now you ask yourselves, “Why this history lesson, Jim?” Well, because we are supposed to be learning about combustion and the era of major combustion advancements — and if I would quit veering off into side topics we might actually get there. But it is all interconnected.

If you recall the story of the heat treater with the bedpost burners (October 2025 edition), he had no inspiration to improve efficiency or performance because those darn bedposts would burn gas just fine. So, what changed? Firstly, the world had been through a couple of military conflicts during this rise of the gas industry. And sadly, sometimes the best technological advances occur in times of conflict; engineering becomes more precise. All of a sudden, instead of hammering out horseshoes for the cavalry, we were heat treating gun barrels and crankshafts for airplanes. We needed to be more than precise — actually, we had to be perfect. So, we stepped away from the old heat treatment ways and developed systems that we could control to within a couple of degrees.

As a result, burners became specialized. Each process became unique and precise. Instead of pack carburizing components, a company called Surface Combustion developed a piece of equipment called an Endothermic generator. This device made carbon-based atmosphere out of natural gas or propane- and nickel-based catalysts. All of a sudden, we could do very precise non-scale covered heat treating. And the burners from companies like North American Combustion, Eclipse Combustion, Maxon, Hauck, Pyronics, Selas, W.B. Combustion, and on and on, all scrambled to develop the specific types of burners that the heat treaters and iron and steel makers needed.

Another important milestone hit around 1963: the Government got involved (gasp!). The Clean Air Act of 1963 essentially said we needed to burn our fuels cleanly and not spit smoke into the air. Those laws got reviewed again in 1970, 1977, and again in the updated Clean Air Act of 1990 with some of the biggest revisions.

With all of these changes, we had several drivers for innovation in the combustion world. Again, precision became a must. Heat treating became a very standards-driven industry. Metallurgists roamed the planet inventing both new materials and the processes to achieve them. Gas companies themselves became huge drivers of innovation and developed think tanks, like the GRI (Gas Research Institute), where people learned and laboratories hummed with development projects investigated in conjunction with burner and furnace companies. Academia became involved with industry in the form of organizations like The Center for Heat Treating Excellence (CHTE) and the Metal Treating Institute (MTI). Suddenly, the industry was more than just blacksmiths.

We’ll talk about how burner companies became design specialists and system efficiency experts and what that meant to various burner styles in next month’s offering.

References

Lowe, Jet. 1994. Panorama of Industry (Conrail Port Perry Bridge, Spanning Monongahela River, Port Perry, Allegheny County, PA). Historic American Engineering Record, HAER PA,2-POPER,1-2. Library of Congress Prints and Photographs Division.

About The Author:

Jim Roberts
President
US Ignition

Jim Roberts president at U.S. Ignition, began his 45-year career in the burner and heat recovery industry focused on heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.

For more information: Contact Jim Roberts at jim@usignition.com.

Flame and Fire: History of the Industrial Gas Industry Read More »

Ask The Heat Treat Doctor®: What Masks the Steel’s Surface in Case Hardening?

/ HARDENING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH

Ask The Heat Treat Doctor® has returned to bring sage advice to Heat Treat Today readers and to answer your questions about heat treating, brazing, sintering, and other types of thermal treatments as well as questions on metallurgy, equipment, and process-related issues.

This informative piece was first released in Heat Treat Today’s November 2025 Annual Vacuum Heat Treating print edition.

Case depth, case uniformity, and final mechanical (as well as other) properties rely not only on controlling both equipment and process variability during heat treatment, but on having clean, properly prepared part surfaces prior to and during heat treating. Expert Dan Herring encourages to learn more below.

Case hardening is a thermochemical surface treatment process designed to add a particular element or combination of elements to a material such as steel. Familiar examples include carbon (carburizing); carbon and nitrogen (carbonitriding); boron (boriding); nitrogen (nitriding); and nitrogen and carbon (nitrocarburizing — ferritic or austenitic). These processes are typically designed to increase the near surface hardness of steel after quenching.

However, various problems can arise due to either the materials or the manufacturing methods employed prior to or during heat treating that will retard or prevent absorption and/or diffusion of the desired element(s) during heat treating. Some of the metallurgical consequences can include:

  • Shallow or uneven case depths
  • Surface oxidation
  • Intergranular oxidation or decarburization
  • High levels of retained austenite
  • Soft spots due to incomplete hardening

Machine-Induced Surface Conditions

Improper machining prior to case hardening can compromise surface integrity. Tooling choices, improperly maintained equipment, inadequate operator training, and even environmental factors can contribute to a variety of issues.

While machining problems occur frequently, they are mostly preventable. Attention to part surface condition, cleanliness, and mechanical integrity is essential before heat treating. Training, standardizing machining protocols, planned preventative maintenance programs, and part inspection prior to heat treating will help avoid these issues. Consult Table A for further details on how the causes and effects of undesirable machine-induced surface conditions can be solved.

Splatter of Stop-off Paints on Unintended Areas

A material that masks the surface of steel and delays or prevents case hardening is called a stop-off or maskant. These materials are applied to specific areas of a steel part to prevent the diffusion of hardening elements (like carbon or nitrogen) into the surface during case hardening processes, such as carburizing, nitriding, or carbonitriding. (See Table B.)

Enriching Gas Additions (Sooting)

During the carburizing or carbonitriding process, it is not uncommon to develop a layer of soot on the surface of the parts, especially if the enriching gas additions begin before the entire load is uniformly up to temperature. In some instances, the amount of soot formation is such that the case depth or uniformity is affected. This is often difficult to diagnose, as the soot layer “washes off” during quenching in a liquid, and the part surfaces come out of the furnace looking reasonably clean.

The use of scrap in steelmaking, especially for low alloy case hardening steels can lead to a relatively high level of impurities and tramp elements. At high temperatures these impurities tend to segregate at grain boundaries and migrate toward the surface. This type of segregation can retard case hardening by impeding element (e.g., carbon) transfer. For example, the effects of tin (Sn) and antimony (Sb) on the kinetics of carburization are particularly problematic (Figure 1).

The effect of tramp elements on retardation of carburization can be expressed in the following order (Andreas, et al. 1996), namely Sb > Sn > P > Cu > Pb. To see the effect of one such element, the carbon transfer coefficient (ß) for typical commercial steels is shown as a function of antimony (Sb) content (Figure 2).

In Summary

These are a few of the many causes delaying or preventing case hardening from being effective. There are many others, including alkaline cleaning compounds (in too high a concentration) and even phosphate and other drawing lubricants used in the manufacture of fasteners. Inspection and cleaning of the part surface prior to case hardening will avoid many of these issues. Reviewing material certification sheets for elements known to interfere with case hardening is also an effective way to anticipate problems with case hardening.

References

Herring, Daniel H. 2014. Atmosphere Heat Treatment, Volume 1. Troy, MI: BNP Media.

Herring, Daniel H. 2015. Atmosphere Heat Treatment, Volume 2. Troy, MI: BNP Media.

Ruck, Andreas, Monceau, Daniel, and Grabke, Hans Jürgen. 1996. “Effects of Tramp Elements Cu, P, Pb, Sb, and Sn on the Kinetics of Carburization of Case Hardened Steels.” Steel Research 67 (6): 242–48.

About the Author

Dan Herring
“The Heat Treat Doctor”
The HERRING GROUP, Inc.

Dan Herring has been in the industry for over 50 years and has gained vast experience in fields that include materials science, engineering, metallurgy, new product research, and many other areas. He is the author of six books and over 700 technical articles.

For more information: Contact Dan at dherring@heat-treat-doctor.com.

For more information about Dan’s books: see his page at the Heat Treat Store.

Ask The Heat Treat Doctor®: What Masks the Steel’s Surface in Case Hardening? Read More »

Sigma Phase Metallurgy 101

/ ALLOY FABRICATIONS TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH

In this Technical Tuesday installment, Nick Hicks, metallurgical services manager at Rolled Alloys, emphasizes the importance of mastering the basics of sigma phase metallography in stainless steels. Understanding these fundamentals helps you know when to consult a metallurgist and guarantee top performance of heat treated parts.

This informative piece was first released in Heat Treat Today’s November 2025 Annual Vacuum Heat Treating print edition.

Heat treaters are always seeking new methods of heat treat and new alloys to improve performance at a lower cost. In the world of stainless steel, there are well-known choices like 310 and newer options like RA 253 MA®. These alloys have exceptional qualities, especially RA 253 MA, which has creep strength up to 2000°F and oxidation resistance up to 2000°F. However, heat treaters should be aware of a potential issue when using such alloys: the formation of sigma phase over time.

In some cases, premature wear in nickel alloys was attributed to sigma phase embrittlement, but it’s important to note that sigma phase does not actually precipitate in nickel alloys. Instead, the actual microstructure may exhibit grain boundary oxidation or carbides. This article seeks to provide a clearer understanding of sigma phase metallography and its impact on stainless steels.

Definition of Sigma Phase

Sigma phase is an intermetallic compound made up of chromium and iron. It is hard, brittle, and non-magnetic. At room temperature, the presence of sigma phase can make the material so brittle that a sudden, hard impact can shatter a piece of metal that contains it, similar to a piece of glass. Pure sigma phase forms when the chromium content is between 42% and 50%, and it is one of the equilibrium phases in the iron-chromium phase diagram as seen in Figure 1.

The peak temperature for sigma phase formation in a 46% Cr alloy is 1510°F. A literature review reveals that different sources cite varying temperature ranges for sigma phase formation. This variation is due to each alloy having its own unique sigma formation range. According to one expert (Kelly 2005), sigma phase can form in the temperature range of 1100°F–1600°F (590°C–870°C).

Metallurgy of Sigma Phase

Many engineers require assistance in distinguishing between sigma phase and the formation of grain boundary oxides and carbides. Otherwise, they might reach incorrect conclusions. Sigma phase is a precipitation product that can manifest in both individual grains and along grain boundaries. Examples of sigma phase formation can be observed in Figures 2–4.

When observing nickel and certain nickel alloys like RA330®, confusion can arise due to the presence of grain boundary oxidation or carbide formation. These occurrences are often mistaken for sigma phase formation by engineers, but it’s important to note that a nominal nickel content of at least 35% is sufficient to prevent sigma phase formation.

Figure 5 depicts RA330 after a 3,000-hour duration at 1900°F. Despite 1900°F being significantly higher than the sigma formation range, some engineers determined that the grain boundary oxides were sigma phase. When there is any uncertainty, it is advisable to consult with a metallurgist who is knowledgeable about the metallography of these alloys.

Physical Properties of Material with and without Sigma Phase

Table A displays the results of impact testing for six different alloys aged at three different temperatures for varying durations. All the alloys experienced some degree of deterioration over time, with certain alloys showing significant losses and reduced ductility. Further analysis revealed that each alloy has its own specific temperature at which sigma phase formation occurs most rapidly. In fact, the formation of sigma phase is dependent on the time at temperature, which makes a C-type curve.

Figure 6 depicts the time temperature transformation curves for sigma phase formation for a few different stainless steels. Any point past a specific alloy’s curve results in the formation of sigma phase.

The results of elevated temperature impact testing for six alloys are presented in Table B. Many of the values in the table indicate that these alloys generally show either no loss of ductility or significantly less loss of ductility when the testing is carried out at elevated temperatures. In most cases, the materials still exhibit sufficient ductility to be safely used at these temperatures.

When these alloys have formed sigma phase and then cooled to room temperature, it’s important to prevent any kind of impact. At operating or heat treating temperatures, these alloys generally maintain enough ductility to be safely used.

Table D displays the results of Charpy testing conducted on RA330 after aging. Although there is a slight decrease in ductility, the material still exhibits sufficient energy absorption to be considered quite ductile and safe for use at room temperature.

Conclusion

Sigma phase precipitation is a phenomenon that occurs in stainless steels and alloys containing less than 35% nominal nickel content. This does not occur in nickel alloys with 35% nickel or more. Sigma phase can make materials very brittle at room temperature. However, at elevated temperatures within typical heat treating ranges, most materials retain sufficient toughness to be used without any concern. It’s important to note that even at high temperatures, toughness is lost. More caution should be exercised in choosing alloys for vibrating systems, as constant vibration can cause premature failure if sigma phase has formed.

Engineers may mistakenly identify grain boundary oxidation or carbides as sigma phase formation in alloys that do not actually form sigma phase. To ensure accurate conclusions, it is important to have interpretations verified by experienced metallurgists who are familiar with the metallography of stainless steels and nickel alloys.

An understanding of the basics of sigma phase metallurgy in stainless steels will help the heat treater, manufacturer, and end user avoid failures associated with sigma phase embrittlement.

References

Andersson, Thomas, and Thomas Odelstam. 1984. Sandvik 253MA (UNS S30815) – The Problem Solver for High Temperature Applications. Sandviken, Sweden: R&D Centre AB Sandvik Steel Bulletin, October.

ASM International. 1986. Binary Phase Diagrams. Metals Park, OH: ASM International.

Crucible Inc., Materials Research Center. 1972. Private Communications, January 10 and June 22.

Herring, Daniel H. 2012. “Sigma Phase Embrittlement.” Industrial Heating. Troy, MI: BNP Media, March.

Kelly, James. 2005. Heat Resistant Alloys. Rolled Alloys. https://www.scribd.com/document/90619472/HeatResistantAlloys-RolledAlloys.

Lien, George E. 1968. Behavior of Superheater Alloys in High Temperature, High Pressure Steam. New York, NY: The American Society of Mechanical Engineers.

Rolled Alloys. n.d. Internal Reports. Temperance, MI.

Rolled Alloys. n.d. Rolled Alloys Bulletin 1353: RA 353 MA® Alloy. Temperance, MI.

About The Author:

Nick Hicks
Metallurgical Services Manager
Rolled Alloys

Nick Hicks is the metallurgical services manager at Rolled Alloys. He holds a bachelor’s degree in mechanical engineering from the University of Toledo and a master’s degree in materials science from Worcester Polytechnic Institute. Nick represents Rolled Alloys at organizations such as the Materials Technology Institute (MTI) and the American Society for Testing and Materials (ASTM). He is also a former Emerging Professional on the ASM Heat Treat Board. Nick specializes in stainless steel and nickel alloy metallurgy for high-temperature and corrosion-resistant applications.

For more information: Contact Nick at nhicks@rolledalloys.com.

This article was initially published in Industrial Heating. All content here presented is original from the author.

Sigma Phase Metallurgy 101 Read More »

Heat Treat Radio #127: The Case for Modular Vacuum Heat Treating

/ HARDENING TECHNICAL CONTENT, HEAT TREAT RADIO, MANUFACTURING HEAT TREAT TECH, QUENCHING TECHNICAL CONTENT, VACUUM FURNACES TECHNICAL CONTENT

In this episode of Heat Treat Radio, host Doug Glenn invites Dennis Beauchesne of ECM USA to explore the technology, benefits, scalability, and sustainability of modular heat treating systems. Together, they discuss how shared utilities, automated transfers, and adaptable heating cells can replace multiple standalone furnaces without compromising quality or precision. Learn how these systems streamline and simplify operations for future expansion — one cell at a time.

Below, you can watch the video, listen to the podcast by clicking on the audio play button, or read an edited transcript.

The following transcript has been edited for your reading enjoyment.

Introduction

Doug Glenn: I am very privileged to have with me today, Dennis Beauchesne from ECM USA. We’re going to be talking about modular heat treating systems, which is a growing category of equipment.

ECM Synergy Center (00:50)

Doug Glenn: Tell me about ECM’s Synergy Center, which is where you are at right now, on the shop floor.

The ECM Flex 600TG vacuum furnace located in the ECM Synergy Center Source: ECM USA

Dennis Beauchesne: I’m standing here in the middle of our Synergy Center. It’s about a 5,000-square-foot facility that is dedicated to proving out client parts for testing various processes, mostly LPC, but we also do a number of other processes here. We have a full metallurgical lab, 3D microscope, a number of tools, including a CMM that we can do before and after heat treat distortion testing for clients that want to know how much their parts move.

It’s a dedicated center just for clients to use. We also use the center for pre-completion of installations, final testing, and training, such as training on maintenance, understanding the software, and how everything works together.

Doug Glenn: It’s proof of process plus much more — helping clients’ proof of process.

Dennis Beauchesne: Absolutely. That’s a big part of convincing people that this process is for them and that it works on their part. We can send them ten different reports of an exact same material and part, but they want to know what their part will do.

What is Modular Heat Treating? (02:50)

Doug Glenn: On a very basic, rudimentary level, what is modular heat treating and how does it differ from what might be considered standard or normal heat treating?

Dennis Beauchesne: A modular heat treat system is one that works together to have more than one furnace working in the same platform. You may have a shop that has five or six vacuum furnaces separated — they each have their own door, vacuum system, electrical supply, quench motors…those types of components. Or you may have a series of batch IQ furnaces for carburizing; those systems are one off, which means they are individual, independent systems.

In a modular system, you try to utilize those facilities for the use of multiple heating chambers. Instead of having one vacuum furnace with one set of pumps and one gas quench motor, what we would do is have three to eight heating cells that would be utilizing one quench, depending on the process timing; that’s all done with an internal transfer car and we try to utilize one vacuum system. It’s much smaller than what you would have for three, four, or even eight cells.

If you had oil or high pressure gas quenching, which is what’s dominating right now in the modular heat treat business, you could supply basically six batch IQ hot zones to one oil quench.

The savings then are huge simply by removing five or six other quench tanks in front of this system, as well as leveraging the floor space (and the number of pits you have to dig). Other advantages including utility savings and utilizing equipment across a number of heating chambers.

Doug Glenn: This modular approach is basically separate chambers that are dedicated to doing whatever that chamber is doing, and they are all in some way interconnected. For standard units, you would heat up, pre-process, do the actual process itself, cool down, all in the same chamber. In a modular unit, you move from chamber to chamber to do each of those separate steps.

Dennis Beauchesne: Yes, I refer to it as a continuous batch.

Doug Glenn: Continuous batch. We were talking before we actually hit the record button with your colleague there, Allison DeAngelo, who just got done visiting the Heat Treat Boot Camp. We were talking about different types of furnaces, and we started talking about continuous vacuum, which of course, is almost a misnomer — a vacuum can’t be continuous because you have to open it up and break the vacuum to get stuff out. Anyhow, we talked about it basically being a batch, right? A batch furnace that’s continuous, a continuous batch furnace.

Benefits of Modular Heat Treating (06:35)

Now that we have a basic understanding of what these modular systems are, why would companies want to move from the standard type of heat treating system to a modular system?

Dennis Beauchesne: Manpower. If you are running five or six vacuum furnaces, you are going to need a number of people to open the doors, put new loads in, those kinds of tasks. With a modular system, you only have one entry or one exit area. Therefore, you are only going to load once every 15-20 minutes, and the system is going to take over and control that load going through the system.

In addition, especially in a carburizing atmosphere situation, you can have every load be a different case depth — a different process in each cell — and then the next load that goes in that same cell can be totally different from the one before. For instance, if you had a batch IQ, you typically use the same carbon potential, and you are typically going to run the next load almost identical to the one before. In contrast, with the modular system, each cell can run a different process every load.

It’s also easier to integrate automation if you are doing capacity increases.

Throughput Comparison (08:00)

Doug Glenn: What is the comparison of throughput between a standard unit and a modular unit?

Dennis Beauchesne: The throughput comparison is interesting because you typically can use a little higher temperature for a carburizing and a little higher carbon potential, and of course that’s what we specialize in here with the modular systems. You can achieve about a 30-40% gain in your cycle time. That furnace is operating very close to 100% occupancy, because when that load is done, you are moving it out right into the gas quench. Then, the next load comes and goes right into it.

Doug Glenn: You are able to increase your throughput because you have basically 100% utilization of the equipment or very close to that. Comparatively, you don’t necessarily have that in the standard equipment.

Product Quality Comparison (09:15)

Doug Glenn: Do modular systems produce higher quality products?

Dennis Beauchesne: The quality of the parts coming out of the system is improved. A vacuum environment is a very clean environment, especially if we are considering atmosphere and low pressure carburizing — it’s in a vacuum. We typically do everything in high pressure gas quenching. However, even in oil quenching under vacuum, you are going to have a much cleaner part.

Also in low pressure carburizing, the carburizing is much more uniform throughout the part because we heat it to temperature under nitrogen before the part gets to austenitizing temperature to start attracting carbon. We make sure that the full part, that’s the tooth, the root, every piece of the part, is at temperature before we start adding carbon to the load, which makes a more uniform case depth, and therefore makes a stronger part.

Doug Glenn: Since each module, each chamber, is dedicated to doing what it is supposed to do, it seems like the consistency and the reliability of the parts being processed in a modular system have a much better chance of being higher quality.

Dennis Beauchesne: You do not have six different variable chambers or six different variable systems. You just have to look at monitoring the connection between those and understanding that the vacuum levels are all the same across the levels and across the cells. Each cell can meet a different temperature and run a different process, but those are consistent across the board.

Typical Dedicated Cells/Chambers (11:10)

Doug Glenn: What would be the typical dedicated cells/chambers of a modular system?

Dennis Beauchesne: It is dependent on the processes. They are most widely used for vacuum carburizing. For pre-oxidation and preheating, we usually use an air oven outside of the system, and we connect that with an external loader. Before the load goes into the modular system, the load will go through a regular air oven, be heated to around 700°F (400°C), and then the load will be moved in.

For sintering and those kinds of applications, there is a debind step or a preheat step that would be done in one cell. Some of the processes that can be done in a modular system include:

  • Low pressure carburizing
  • Low pressure carbon nitriding (LPC)
  • FNC (ferritic nitrocarburizing)
  • Nitriding
  • Debinding
  • Sintering
  • Neutral hardening

The most prominent process right now is LPC, and that is being used all over the world in these systems.

Advantages of a Modular Unit for Captive Heat Treaters (12:53)

Doug Glenn: Why would a modular unit be beneficial for a captive heat treater, someone who does their own in-house heat treating, which probably means they’ve got potentially high volume, low variability as far as their workloads?

Dennis Beauchesne: The modular unit has many different advantages. First of all, floor space. You are going to save a lot of floor space by not having multiple furnaces set up separately. You will also save utilities because you would not have as many vacuum pumps or electrical systems running these furnaces on their own. You will have some shared service and utilities in that fashion.

Doug Glenn: That would also likely lead to maintenance cost savings as well, correct?

Dennis Beauchesne: Yes, it all goes down the line. Anything that you have multiples of, you are going to have much less costs than on a joint system. The modular system might be a little larger than one singular unit, but there will be fewer of them.

For vacuum carburizing applications in a captive shop, the quality and cleanliness of the part is very, very important. Gas quenching lends itself to no oil in your plant, no washers necessary for a post-quench. Typically, there’s a washer before the process starts, but you do not have to have any wash to get the oil off of the parts with a modular unit — you do not have to reclaim the oil or the water from the washer. You would not have waste oil in your plant either or any oil on your plant floor. These are some of the reasons some of the larger captive shops have gone to the modular systems.

Also, safety: There are no open flames with a modular unit, no risks of fire on the systems. They are also easier to maintain. For a fully operational, let’s say, eight-cell system for high production, captive operation, it would only take about five hours to cool that whole system down if you had to go in and work on the whole system. In comparison, it’s going to take you three to four days sometimes to cool down a typical atmosphere, high-temperature furnace.

It also takes time to heat the system up again. In a modular system, it takes about an hour and a half to heat the system up again and then you are ready to start running. That means now you can schedule your downtime on weekends or holidays. You do not have to have staff present to run anything.

You also do not have to have a secondary equipment, like Endo generators running to feed the carburizing gas. The carburizing gas is using acetylene out of cylinders, it’s not a regenerative system. You do not need a separate piece of equipment to feed to the furnace.

Another benefit is CapEx expansion. Typically, captive heat treaters do not want to buy everything upfront because their volumes are going to increase over time. In the beginning, they typically only need one or two cells ready to do a small amount of production so they can prove out the production and prove out the system. Then they can start building the system with more cells and more capacity later on. Generally, it’s two to three days of downtime to add a cell to a system. It’s very convenient to do that with a modular system. All of the utilities are typically alongside the modular system so that you can easily add those or add a cell to it over a short period of time, and those cells can be ordered a year or two down the road whenever you might need that.

You also can order peripheral equipment, like extra temper ovens or additional automation. You can add a robotics system to the layout as well. That’s why captive shops are very interested.

Finally, workforce: It’s a little bit easier to get someone to work on a modular system. These systems are completely clean and white. The one located in our Synergy Center has been there for eight years. We use it every single day, and it’s a very clean aesthetic environment for someone to work in. These systems are also water cooled, which means not a lot of extra heat in the building around you to work in.

Advantages of a Modular Unit for Commercial Heat Treaters (17:59)

Doug Glenn: What are some advantages of modular units for commercial heat treating?

Dennis Beauchesne: On the commercial heat treat side, modular units are typically useful because you can get multiple processes out of similar cells and you can have a system that has oil and a gas quench.

You can have a lot of flexibility in that one system that you have in the plant. I’ve visited hundreds of captive and commercial heat treaters. They generally have a number of furnaces in one area of the plant, and a number of furnaces in another area of the plant. A modular system gives you all the capability in one machine and one tool: oil quenching, gas quenching, FNC, nitriding low pressure, carburizing, carbonitriding, and neutral hardening all in one piece of equipment.

Automation and Robotics with Modular Heat Treating (18:57)

Doug Glenn: What automation and robotics advantages are there with modular systems?

Dennis Beauchesne: This is the new trend. People that have modular systems are now considering, “How do I automate the system to get more production out of it?” And what we’ve been doing the last five years especially is implementing systems that use CFC fixtures.

CFC fixtures are very robust in the furnace but sensitive to being controlled outside. Therefore, what we try to do is have the CFC fixtures be utilized in an automation that no humans have to interact with it. We usually use robots for external loaders and internal loaders to move the fixtures through the process.

This causes you to have a lighter load, which means less heating time, less energy being consumed. Also, the fixtures last three to four times longer if they’re not damaged. But of course, all of these systems can be using regular alloy steel as well, and we can fixture different parts. You can use baskets, we are now doing bulk loading where we have parts that are filled into baskets and then processed. We are doing that with vacuum carbonizing as well, not just neutral hardening.

So it’s really interesting to see how the limits are being pushed, as well as the different materials that we are gas quenching now. I know 20-25 years ago, we were quenching some simple materials that were very high hardenability, and today we’re quenching a lot of less hardenability steels.

Doug Glenn: Is that primarily due to increase of pressure in the quench?

Dennis Beauchesne: It’s pressure, it’s flow, it’s the intensity of the gas going through the parts. It’s also heat removal as well — heat exchangers, removing the heat out of the load faster. We also have reversing gas quench motors to reverse the flow inside from top to bottom, bottom to top, in the middle of the cycle.

Sustainability of Modular Heat Treating (22:24)

Doug Glenn: Do these systems promote sustainability and greenness?

Dennis Beauchesne: Absolutely, especially when it comes to carburizing. These systems have been compared against typical atmosphere carburizing cycles, and only about 4% of the carburizing time has gas injection, when we are actually injecting acetylene and having hydrocarbons being used in the process.

If you took the same cycle times, seven or eight hours of a carburizing cycle, you are flowing Endo gas or nitrogen methanol in the system for that full time. In contrast in a vacuum carburizing system, it’s 4-5% of the time of the cycle that you’re injecting into the furnace. Ultimately, you only have about 10% of the CO2 output that you would have in a typical atmosphere furnace.

As mentioned previously, there’s also no oil in your plant. You’re not reclaiming oil out of the water and the wash or off the floor or in your car when you leave your heat treat shop.

How Does the Modular Heat Treating System Work? (23:40)

Doug Glenn: Let’s talk through the process a little bit. You provided us with figures to aid in describing the process. We have included these. Describe how the system works.

Dennis Beauchesne: This animation is a plan view of one of our Flex systems. In the center, going left to right, is a tunnel section. This tunnel section is about an 8-foot diameter. It has an automated loader that moves down left to right or horizontally, and it transfers loads from each cell to another, in and out.

On the bottom left is a loading/unloading chamber. In that loading/unloading chamber, we remove the air once the load is put in there, and then we balance the vacuum on that cell to the tunnel’s vacuum. Then we’re capable of moving that load to an available heating cell, and that would be on the right of the system — on the top right or the bottom right of the tunnel, those are heating cells. Then recipe for that particular load will be loaded into that cell. While that load is processing, another load will be moving into the tunnel and into the other heating cell as well.

On the top left is the gas quench cell, which could be in this orientation or instead have an exit on the back as well. In this system, you could do neutral hardening, carbon nitriding, LPC, a number of the processes. This is a very valuable tool, especially in a commercial heat treat heat treat shop.

Doug Glenn: Is this whole unit, including all four chambers under vacuum? I noted there are separation doors on the purge and the entry chamber. Can this area be vacuum sealed?

Dennis Beauchesne: Yes. There are vacuum seals on the loading/unloading chamber on the bottom left and then the top left. The gas quench also has a seal from a pressure standpoint. The two heating chambers have a graphite door — we call it the flap door, and it just flaps and it doesn’t really seal actually against another face of graphite. It’s graphite-to-graphite. We pull vacuum out of there through the tunnel to create the central vacuum pressure in the system. We also pull vacuum from the cell itself, and we could also have a separate door on the front of the unit if the process necessitates that or if we feel that a door is needed there by a client.

In a normal state or a standard unit, there are no hot seals on the door, only vacuum seals on the loading/unloading chamber and the gas quench.

Doug Glenn: In the animation, your vacuum pumps are down in the bottom right, correct?

Dennis Beauchesne: Exactly, that’s a process pump.

Doug Glenn: What is located in the top left?

Dennis Beauchesne: On the top left, we have a gas quench tank. We want to ensure we have enough gas pressure and volume there to quench the load quickly. It’s very important to get the gas through the gas quench quickly.

ECM Flex 600TG vacuum furnace with two added heating cells / Source: ECM USA

Now, we have added two more additional heating cells and a central tunnel section. In essence, you just doubled the space, doubled the capacity of the unit, where you only added 50% of the space of what you had for capacity before.

We are still utilizing the same gas quench and the same loading/unloading cell. We only added utilities for the two heating cells, not for a whole gas quench or oil quench capability there; this can be added in a very short time.

Doug Glenn: Now I’m gonna go let this video roll here for a minute. There we go.

ECM Flex 600TG vacuum furnace with four added heating cells for six heating  cells total

Dennis Beauchesne: So now we added another 50% capacity with two more heating cells (six heating cells total) and a tunnel section. Typically, what you want to do is to have the tunnel sized for about five years out for your capacity and then buy the cells as you need them and have it grow so then the tunnel is ready to implement.

We have just tripled the capacity of this installation, and we are only still using the same gas quench and the same loading/unloading cell. Generally, this system could go to eight cells and have just one gas quench, that’s our typical orientation.

Doug Glenn: It looks like we also added a discharge side here. Whereas before we were going in and out.

Dennis Beauchesne: Yes, this adds to the efficiency of the system because the load is already in the gas quench when it’s finishing, so it just exits out the back, out the door.

Doug Glenn: Now what do we have here?

ECM Flex 600TG vacuum furnace processing different treatments in each cell. See animation above to watch the animation in motion.

Dennis Beauchesne: We have the loads entering, and the loads will go to the first cell that is available (empty). Then that recipe would be downloaded for that cell, and then the next load will go to the next available heating cell and download that recipe into that cell. These could be two different loads.

One load could be for neutral hardening; one could be for carburizing. One could be for carburizing in a low case depth. The other one could be carburizing at a deeper case. In this case, we just see the gas quench on here, but this tunnel could also be outfitted with an oil quench as well, and you could have one load go into gas, quench one load, go into oil quench or both going to either.

Doug Glenn: This gives people a sense of what the process looks like.

Processes and Materials for the Modular System (30:29)

Doug Glenn: Are there any processes or materials that do not make sense to process them through one of these systems?

Dennis Beauchesne: If you are doing a lot of annealing and normalizing, those are longer cycles. There is some regulated cooling that occurs. This is not really the type of equipment investment that you would want to make for those processes. If you were going to use it for a few loads in your plant where you received parts that weren’t annealed or you wanted to try to anneal a part for a particular process before you went to full production, you could certainly use a modular system for that, but it’s not a cost effective methodology. Neither would we recommend preheating in the cell. However, it is very flexible for a number of other processes that we have mentioned.

The size of the part is also important to note. These systems are typically 24 inches wide and about 39 inches long and about 28 inches high. However, we will soon have a new system, the Flex Max, a 12-9-9 system. It’s a 36×48 unit that comes with an oil quench and is modular, like this. We can either do an oil quench or a slow cool cell on that system. So, we will have that capability of 36×48 in that modular system.

Other than that, restrictions on material? Very few there. Like I said, you would not want to do annealing and normalizing on a lot of parts, but you could do it in these units.

Doug Glenn: It sounds like the sweet spot is surface modification type applications, and some sintering is possible with dedicated chambers.

Dennis Beauchesne: Yes, sintering and brazing is also possible.

Doug Glenn: Does that include aluminum brazing?

Dennis Beauchesne: Not aluminum brazing, but some brazing applications.

Expenses with Modular Heat Treating Systems (33:03)

Doug Glenn: What would be considered capital expenses for this modular system?

Dennis Beauchesne: As far as capital expenses, it’s not a furnace-to-furnace comparison. Clients always ask how much our furnace is. But companies need to first take two steps back and take a look at their incoming material, how they would like to be able to modify that incoming material in their heat treat process to make sure that their outgoing quality is higher than it is today. That’s the kind of benefit that this type of modular system gives you — a better quality part, safety in your plant, and a better quality work environment with being able to turn the system off and not need additional personnel around.

These are all factors that have to be considered when thinking about the CapEx expenditure and investment. When we consider these factors, a modular system investment is a much better situation than looking at a furnace-to-furnace replacement, and that’s really the thought process that clients need to go through to understand the actual investment and value of the system.

Doug Glenn: What about the operational expenses?

Dennis Beauchesne: For instances, if you had a batch IQ sitting there, you would typically keep it running whether it has a load in it or not. With a modular system, you just shut off that cell that you’re not using. It does not take any more energy. If you are not working five days a week, you do not use it on the weekends — you shut it off. You do not use it during Christmas shutdown or any holiday shutdown, vacation shutdown. You’re able to shut it off and that means saving a lot of energy and labor by having it off.

Also, in the opposite way, you could run it lights out if you wanted, as well. You could stock up a number of loads on the automation before you leave, have the system operate it, run it, and have the load come back out before the morning. You could have it time start as well, if you wanted to start it on Monday at 5 AM, but you will not be there till 8 AM. You would come in and the furnace would be hot and ready to run a process.

There are a number of operational advances over the typical operational heat treat that’s out there today.

Doug Glenn: How does maintenance work with these systems? Say your heating element goes bad in cell number three, do I have to shut the whole system down to fix or can I fix number three and leave the rest of the system up and running?

Dennis Beauchesne: In this situation if you had a tunnel like we showed, you would typically shut off that cell; that is, if you knew that heating element was out or it wasn’t heating properly, you could shut off that cell, de-validate is what we call it, and then keep running the rest of the system until you had a window in your production that you could shut the whole system to get into that heating element.

If you had a system with doors on the front, it could be possible to go in the back while the system is operating. Then, it would be all based on your safety requirements for your plant and those kinds of things.

To do that, we have another system called the Jumbo, and it is much more flexible in the maintenance world. It has a vacuum car that moves down on rails and docks and mates with every heating cell on the system. In that line, the heating cell can actually be isolated from the rest of the line. You would just slide it back (It’s on wheels, it slides back about three feet away from the line), you put in a new piece of safety fence, and you continue to run your line. You can completely lock out/tag out that cell and work on it completely.

Doug Glenn: How would you approach a vacuum leak since the whole system is connected, right? I believe you mentioned these are graphite-on-graphite doors.

Dennis Beauchesne: You would want to fix the leak before you move on. Especially if it’s a bad leak. If it’s something that’s causing you to not maintain your process pressure, you certainly don’t want to do that, and that’s true with every vacuum piece of equipment.

ECM Modular Systems (38:55)

Doug Glenn: How many of these modular type systems does ECM have out in the marketplace?

Dennis Beauchesne: The Flex is the most popular modular system, which we discussed with the animation. We also have a number of Jumbos systems, and the unit in our Synergy Center is called a Nano, which has become more and more popular these days. The Nano has three different size chambers, but they’re typically smaller, 20x24x10 inch high size chamber. I explained a little bit about the Flex and the Jumbo is the same.

Out of those three systems, we have more than 350 modular systems, not just the heating cells, but more than 350 systems that are out in the marketplace today operating, running parts every day, running millions and millions of parts every week. Those systems are comprised of about 2,000 heating cells. As much as people hear about this being a new technology, it has actually been around about 30 years, and many companies have been using these systems and have replaced a number of pusher furnaces and those style furnaces for high-capacity installations especially.

Doug Glenn: Okay, that sounds good. I really appreciate your time.

About the Guest

Dennis Beauchesne
General Manager
ECM USA

Dennis Beauchesne joined ECM over 25 years ago and has since amassed extensive vacuum furnace technology experience with over 200 vacuum carburizing cells installed on high pressure gas quenching and oil quenching installations. Within the last 10 years, his expertise has expanded to include robotics and advanced automation with the heat treat industry high-demand for complete furnace system solutions. As General Manager of ECM USA, Dennis oversees customer supply, operations and metallurgical support for Canada, U.S., and Mexico for ECM Technologies. He has worked in the thermal transfer equipment supply industry for over 30 years.

For more information: Contact Dennis at DennisBeauchesne@ECM-USA.com.

Find heat treating products and services when you search on Heat Treat Buyers Guide.Com

Heat Treat Radio #127: The Case for Modular Vacuum Heat Treating Read More »

What’s the Rebricking and Relining Process for My Atmosphere Furnace?

/ ATMOSPHERE AIR FURNACES TECHNICAL CONTENT, INSULATION TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH

This Technical Tuesday installment is part of the Maintenance Message column series. In today’s edition Nate Sroka, quality assurance engineer for Ipsen, provides a complete maintenance guide to rebricking and relining atmospheric furnaces. Keep this one bookmarked for a quick reference to components, the rebricking process, expectations, and project timeline questions!

This informative piece was first released in Heat Treat Today’s August 2025 Automotive Heat Treating print edition.

Introduction

The interior brick walls of an atmosphere furnace endure extreme temperatures — sometimes reaching 2200°F — every hour of every day. Over time, the bricks become brittle, crack, and experience thermal expansion, which can open seams in the mortar.

After years of continuous operation, users may notice exterior walls becoming hot enough to melt insulated cables or components attached to the furnace. When bricks start falling out of place or insulation begins to sag, it’s time to shut down the furnace, assess damage, and plan for repairs. Typically, furnaces operating for five to ten years since installation or their last major overhaul require rebricking or relining.

Understanding the Components: Bricks and Boards

Knowing the key components used in the rebricking and relining process prepares you for discussions about repairs.

Insulated Fire Bricks (IFB) come in various temperature ratings. A 2300°F brick is less efficient and durable under extreme heat than a 2600°F brick but is often more cost-effective. High-rated bricks typically line the interior, while lower-rated bricks provide an additional insulation layer.

Insulating boards made from calcium silicate form the thermal barrier between the heating chamber and external components. They can withstand temperatures from 1000°F to 1800°F and are commonly used in lower-temperature furnaces.

Mineral wool is a fibrous insulating material used to fill gaps around furnace entry points and seams. Made from volcanic rock, ceramic, or slag, it allows for expansion and contraction due to temperature changes.

One key thing to know about atmosphere furnaces is that they are almost always “on.” In a vacuum furnace, recipes use electric elements that shut off after every cycle, and quenching often happens within the same chamber. However, in an atmosphere furnace, turning off the burners and then restarting the furnace from room temperature the next day is much less energy efficient than running the burners and holding a consistent temperature, even when the furnace is empty. Parts from an atmosphere furnace are typically quenched in an oil or salt bath, separate from the heating chamber.

Figure 1. Debris from a damaged atmosphere furnace that collapsed on a hearth
Source: Ipsen

Starting the Rebricking Process: What You Need to Know

Prepare for a Quote

First, review the pre-quote checklist to make sure you have the right information to get an accurate quote.

Pre-Quote Checklist: Important information to have on hand when getting a quote for rebricking or relining your atmosphere furnace

  • Furnace model number and serial number
  • Heating chamber dimensions (w/d/h)
  • Archway dimensions from base to top
  • Door dimensions and condition
  • Drawings or engineering plans outlining any aftermarket modifications
  • Typical operating temperatures
  • Any additional materials installed to prevent heat penetration
  • Photos from as many angles of the furnace as possible
  • A list of any consumable or heavy-wear components that also need to be replaced

Build a Timeline

Start collecting quotes at least a year in advance and place a purchase order no less than six months before the planned shutdown.

Consider Scheduling Factors

Many furnace operators are looking to have work like this completed during a summer or winter holiday shutdown period. Advanced planning improves scheduling flexibility.

Site Preparations

Before the service team arrives, ensure the workspace is ready:

  • Clear space for staging new materials and removing old bricks.
  • Provide access to a forklift, a durable waste collection container, a dumpster, and other required tools and resources.
  • Confirm power connections near the site for welding and other power tools.
  • Review lockout/tagout procedures with maintenance and operations teams.
  • Determine the required furnace cool-down time before disassembly and plan furnace shutdown accordingly.
  • Identify and disconnect any electrical, process gas, or water-cooling lines as outlined prior to service.

Rebricking Day: What You Should Expect

During disassembly, consider performing additional maintenance, such as:

  • Inspecting and rotating or replacing burner tubes
  • Inspecting and replacing pusher chains and skid hearth section
  • Checking doors, door hoods, and fan bungs
  • Conducting leak tests and changing the quench oil

Coordinate these tasks with the service team to avoid disruptions. The rebricking process spans several days, allowing time for concurrent inspections and repairs.

Final Inspection and Testing

Upon project completion:

Figure 2. A newly installed furnace, bricks properly installed, before furnace ignition
Source: Ipsen
  • Inspect the furnace with the installation team to ensure all work aligns with project specifications.
  • Document any changes as a reference for future maintenance.
  • Perform a “dry out” procedure and clean the quench tank before refilling the tank. See “Example Dry Out Procedure” break-out box.
  • Run the furnace without parts to test for temperature uniformity.
  • Carburizing furnaces may need extra burn-in time to “season” the bricks:
    • Fresh bricks absorb free carbon until fully saturated.
    • When bricks are properly saturated, furnace atmospheres stabilize.
    • Time of burn-in is dependent on the percentage of carbon-level the system needs to achieve.
  • Identify potential hot or cold spots that may require further insulation adjustments.

Post-Installation Best Practices

A rebrick or reline of a furnace is a significant investment. To get the most from your furnace, make the time to take a proactive approach:

  • Establish a daily maintenance inspection for the first week, followed by weekly checks for the first month.
  • Resume regular maintenance schedules if no issues arise.
  • Schedule independent inspections with a field service engineer at three, five, seven, and nine years to proactively assess furnace condition and secure preferred maintenance dates.

By following these steps, atmosphere furnace operators can maximize uptime, streamline service quoting, optimize downtime usage, and ensure efficient future rebuilds.

This article was originally published on ipsenusa.com.

About The Author:

Nate Sroka
Quality Assurance Engineer
Ipsen

Nate Sroka has been with Ipsen since March 2014. He holds a bachelor’s degree in mechanical engineering and a master’s degree in engineering and industrial management from Northern Illinois University. Nate oversees the Quality/Documentation/Warranty (QDW) department, ensuring that Ipsen maintains ISO 9001 and ISO/IEC 17025 standards. He is also responsible for documentation related to installation and operations manuals, regulatory certificates, and managing warranty programs.

For more information: Contact Nate Sroka at nate.sroka@ipsenusa.com.

Find heat treating products and services when you search on Heat Treat Buyers Guide.Com

What’s the Rebricking and Relining Process for My Atmosphere Furnace? Read More »

Will In-House Heat Treaters 3D Print the “Cutting Edge”?

/ MANUFACTURING HEAT TREAT TECH, Manufacturing Heat Treat Technical Content, SINTERING POWDER/METAL TECHNICAL CONTENT

If you are one of many heat treat professionals watching AM take over the industrial world with bated breath, it may be time to stop watching and start doing. This article highlights the rapid rise of AM and how changes in your heat treat operations may be needed.

This informative piece was first released in Heat Treat Today’s August 2025 Automotive Heat Treating print edition.

For manufacturers who produce customized or complex parts and components for the medical, aerospace, automotive, and other industries, additive manufacturing (AM) with metals has the potential to bring innovation and agility to the process.

However, because AM is a somewhat nascent technology, there are still challenges to address before it is widely accepted throughout the manufacturing industry. Fortunately, as research and development continue, the aerospace and automotive industries are beginning to acknowledge that parts made via AM are robust enough for use in safety-critical applications. Manufacturers who want to use AM to gain a competitive edge are advised to zero-in on the most suitable method for metals and determine in which applications AM presents an economically viable solution.

The Additive Manufacturing Market

AM, also known as 3D printing, is the process of creating an object based on a digital file, such as a computer-aided design (CAD) or one created with a laser scanner. Unlike traditional manufacturing methods that often involve cutting or subtracting material from a solid block (like machining), AM involves building up thin layers of material — usually metal, ceramic, or plastic — one by one using a 3D printer.

AI-generated image of 3D-printed turbine engine components

AM is increasingly transforming the manufacturing industry, enabling faster prototyping, customized production, lightweight parts, and complex shapes and geometries that would be impossible to manufacture using conventional casting, machining, or subtractive techniques, such as milling, grinding, carving or shaping.

For product design, prototyping, and reverse engineering applications, AM allows designers to rapidly print parts as a single piece, reducing material waste, saving time, and reducing costs, all while getting new products to market faster. Although the same advantages apply to traditional manufacturing applications, manufacturers have not been as quick to adopt the technology.

Still, the AM industry is seeing growth. A recent report from Grand View Research states that the global AM market size was valued at over $20 billion in 2023 and is expected to grow at a CAGR of 23.3% from 2023 to 2030, with unit shipments of 3D printers expected to reach 21.5 million units by 2030 thanks to a growing demand for prototyping applications in the healthcare, automotive, aerospace, and defense industries. The report also acknowledges that rigorous R&D in 3D printing will further contribute to growth.

Additive Manufacturing Techniques for Metals

Currently, three primary techniques are used for AM with metals: laser powder bed fusion (LPBF), directed energy deposition (DED), and binder jetting.

LPBF

LPBF technologies, including direct metal laser sintering, selective laser sintering, and direct metal printing, use a laser to sinter or fuse powdered metal particles until a complete part if formed. LPBF processes typically include heating the bed of powdered metal to a consistent temperature. The printer begins applying the first layer over a build plate, fuses the powder particles together with a high-powered laser, and then continues the process layer-by-layer until the part is finished.

After the part is printed using LPBF, it is removed from the powder bed, cut away from the build plate, heat treated to prevent internal stresses, and finally machined or polished to achieve the desired surface finish.

LPBF is limited by the size of the print bed, so it is not suitable for manufacturing large components or parts.

DED

DED using powdered metals also relies on a laser to produce metal parts. However, rather than spreading powder on a bed, the DED machine blows powdered metal out of the print head and uses a laser to fuse the part during construction.

DED-manufactured parts require post-processing heat treatment and machining steps. And while DED is a faster process than LPBF, there are a limited number of materials that can be used in the DED process, and the technique still needs more research and development before it sees widespread commercial use.

Binder Jetting

Binder jetting deposits a layer of loose metal followed by a layer of binder material layer by layer to create the product. During the process, a binder jetting machine distributes metal powder over the print bed to form an unbound layer. A jetting head then spreads a binder to adhere the powder. The machine continues to spread alternate layers of building material and binder to form a complete product. Sintering is generally required after printing to remove the binder, resulting in a part that is composed entirely of metal.

While binder jetting is a fast process and offers the opportunity to create and sinter parts in batches, it is currently a more expensive option. However, research and development into this technology, the availability of binder jets from companies (e.g., Markforged and HP), and the potential to use binder jetting for high-volume batch production may eventually make binder jetting the technology of choice for metal AM.

Post-Processing Heat Treatment for AM Parts

No matter the print technique, some AM-printed metal parts will require post-process heat treatment in which the printed part is subjected to specific temperatures and durations and then cooled to enhance or customize the properties of the metal material and optimize performance and reliability of the part.

Applying controlled heating and cooling cycles during post-printing heat treatment eliminates internal stresses created during the AM process to prevent distortion, cracking, and warping that would negatively impact part performance and reliability. Heat treating can also be used to increase hardness, density, strength, and fatigue resistance to optimize performance of the part. Furthermore, heat treating can be applied to customize the mechanical properties of the final part and provide specific characteristics so that it performs reliably in the intended application.

The type of heat treatment used following AM will depend upon the printing technique, metal material, and desired characteristics and properties. Annealing, sintering, normalizing, quenching, and tempering are commonly used. Hot isostatic pressing (HIP) — another post-process option that is used to reduce porosity and improve the density, performance, and reliability of AM-printed parts — will be specifically addressed in a subsequent article release.

Greater Acceptance in Industry Sectors

Metal alloy 3-D printed components

While AM has been widely used for prototyping and reverse engineering, adoption of the technology has been slower for the manufacture of finished parts and components. Stephen Feldbauer, director of Research and Development, with Abbott Furnace Co., suggests that the right approach to AM with metals depends upon the ability of manufacturers to refine their application. “Manufacturers should not take the ‘shotgun’ approach of ‘I can print anything,’” comments Feldbauer. “Instead, they should focus on what makes the most sense for them and specialize in those parts rather than just printing something because it’s possible.

However, because it provides significant benefits, AM does have application in the several manufacturing sectors. Advantages in using AM to produce parts include minimization of waste, time and cost efficiency, and the ability to customize parts for single-use applications or low-volume production runs.

Thanks to these benefits, AM is currently being used in the following industries:

  • Aerospace: functional parts, such as engine turbine blades and fuel systems 
  • Automotive: various components, such as suspension systems, engine parts, and door panels
  • Defense: obsolete parts, as well as vehicle and weapon components
  • Medical: implants, prosthetics, and other apparatuses

And, as AM technology continues to expand, it is becoming more widely accepted and is most notably being employed to create safety-critical aerospace and automobile parts. For example, General Motors (GM) announced that it is using AM-printed seatbelt pillar adjustable guide loops in its all-electric Cadillac Celestiq, making them GM’s first safety-related AM-printed metal part. 

The component is made by Azoth using Markforged metal binder jetting technology with a liquid binding agent. Following the process, the metal parts are then sintered, polished, and plated. Automotive sector acceptance of additive manufactured safety-critical parts is a tremendous boon for the AM industry.

Experts like Feldbauer see the need for manufacturers to make a few key decisions for this technology to become a reality. “For additive manufacturing to be a commercially viable solution,” he argues, “manufacturers must determine which parts they can 3D print with high levels of success and where printing is cost effective and profitable. Commercial viability is really the determining factor as to whether a part should be 3D printed or made using conventional manufacturing techniques.”

Currently, though, AM seems to be benefiting smaller jobs. According to Feldbauer, AM usually makes the most sense for small runs where there is a need for customized tooling; in these cases, manufacturers run into too complex of shapes or simply to time or cost intensive.

The Future of AM

While AM is increasingly accepted as a beneficial process across many industries, it still faces challenges affecting its usage more broadly, such as material restrictions, bed or plate sizes for techniques that rely on bed printing, and the need to purchase high-end printers from a market that is constantly consolidating. Research and development into the process, more diversity in technologies, increased availability of AM outsourcing companies, and the benefits associated with cost, time, and material reductions are expected to be a driving force in widespread commercial adoption.

Stephen Feldbauer, director of Research and Development with Abbott Furnace Co., updated Heat Treat Today on the state of AM in 2025

As the technology continues to mature, AM will continue to expand into industries where the availability of high-volume AM production, such as is possible with binder jetting, would reduce the cost of part manufacturing. Additionally, optimizing post-process heat treatment methods will help further enhance the cost effectiveness of AM with metals and enable more customized characteristics. These advances could make AM an attractive and economical option for manufacturers, so those who want a competitive edge should begin to focus and refine application of AM to the parts for which it will be most worthwhile.

References

Grand View Research. 2022.  Additive Manufacturing Market Size, Share & Trends Analysis Report by Component, by Printer Type, by Technology, by Software, by Application, by Vertical, by Material, by Region, and Segment Forecasts, 2024 – 2030. April 2022. Grandview Research. Report ID: GVR-4-68039-922-9. https://www.grandviewresearch.com/industry-analysis/additive-manufacturing-market#

Check out our AM/3D Trivia to test your knowledge of the AM/3D industry, the processes, and the technology.

This editorial was written by the Heat Treat Today Editorial Team.

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The Future Is Coming Three Times Faster Than You Think

/ BURNERS & COMBUSTION SYSTEMS TECHNICAL CONTENT, GUEST COLUMN, MANUFACTURING HEAT TREAT TECH, OP-ED

In this Technical Tuesday installment featuring Combustion Corner by Jim Roberts, president of U.S. Ignition, readers are enlightened about how upcoming policies might impact their burner systems, fuel mixtures, and equipment. Could certain policies impact technical requirements of heat treating? Find out more below.

This informative piece was first released in Heat Treat Today’s July 2025 Super Brands print edition.

A furnace guy goes into a bar and says, “This looks like a fast crowd… and all the players nod in agreement.”

Where are we? It’s the future! And in heat treating and combustion circles, the changes that will occur in the next several years will be very impactful to our industry. We’ve all heard these things, and we have some of the very best experts in the world working for us in this industry to make sure that we continue to grow and to be a leader in the legislation and rules that could cripple the wonderful world of heat treating and metals.

We are lucky to have industry associates at the Metal Treating Institute (MTI) who understand the impact of some of these new regulations. In this year’s Air & Atmosphere issue of Heat Treat Today magazine, Michael Mouilleseaux (Erie Steel LTD) provided updates on the proposed decarbonization initiatives. I have seen presentations by Michael and his committee composed of Heather Falcone (Cook Induction Heating Company) and Ben Gasbarre (Gasbarre Thermal Processing Systems). This is critical knowledge for us all, and we should be staying as vigilant and supportive as we can. Michael’s interview is a must-read in that February issue – if you missed it, go back and read it. Please.

And then you say, “What’s this got to do with combustion equipment and the stuff that this Roberts guy is normally talking about?”

Well, not only does the decarbonization mandate mean the possibility of costs through government burdens and penalties, but the equipment and process change requirements are going to be staggering if we don’t prepare.

As long as I’m in a name-dropping mood, I’m going to mention Brian Kelly of Honeywell. Brian is a degreed aerospace engineer, and yet he decided to come play in the mud with us furnace guys for a career. Brian has several detailed presentations online about some of the prime initiatives for all the combustion equipment companies — hydrogen Combustion. Yep, the “H” word. The holy grail of zero pollution. One of those presentations includes fascinating detailed data on hydrogen and other emission initiatives, given by Brian Kelly and Todd Ellerton on YouTube regarding future combustion technology requirements.

“So, what does the “three times faster” thing mean, Jim?”

Well, all major combustion equipment companies, like Honeywell, understand that hydrogen requires three times the amount of fuel to generate the same amount of available heat as natural gas. Hydrogen also burns with seven to eight times the “flame speed” of natural gas. It burns, on average, about 400 degrees hotter (F) than natural gas. And so, from an engineering standpoint, there are a fantastic number of variations that must be considered as we look forward, especially when addressing CO₂ and other emissions. Add propane, butane, methane, producer gas, landfill gas, and anything else that is presently being utilized in the heat treat circles, and that provides a lot of possible variations!

Now, it needs to be said that a good many burners can burn hydrogen already. The anticipation of this level of scientific and ecological requirements was seen a long time ago. Conversely, many cannot. Brian Kelly explains that 17% of the present pre-mix/blended fuel systems cannot utilize this fuel. It also bears mentioning that there are three different grades of hydrogen production levels.

So, let’s start doing the math on how many iterations it will take. But here is the biggest tidbit of hydrogen science in the combustion world – hydrogen is the smallest molecule and the lightest in a molecular sense. Helium is smaller and lighter, for fact-checker purposes, but we aren’t trying to burn helium, are we? So, as we blend hydrogen with our other fuels (i.e., the most practical way to maintain some of the infrastructure and equipment), we need to have our combination equipment suppliers test and verify that which exists will work.

Obviously, if it takes three times the fuel volume, existing gas delivery lines will be an issue. At the molecular level, smaller and lighter means that many existing seals, connections, and control valves may no longer be gas-tight and may leak. That’s not good! If the flame speed of these fuels is five to eight times that of existing fuels, temperature profiles within the process will need to be reviewed and re-calibrated. And if it burns 400 to 500 degrees hotter, certainly that will require a review of the former materials of construction.

So, how does this tie into the original theme of “The future is coming fast?” Well, we have just touched briefly on one possible fuel transition that is on the horizon. Carbon points/credits are already being taxed in Europe. We can bet that these global decarbonization efforts will be moving ahead. We will need a review so that a “head in the sand” mentality does not catch any of us in the thermal processing community flatfooted and ill-prepared.

It’s easy to think that it won’t affect you. When I mentioned “three times as fast,” of course, I was alluding to the fuel references, and the best way to be prepared for the future is to see it coming. Be alert and stay current, and we will adapt as an industry, as we have so many times before. Until next time …

About The Author:

Jim Roberts
President
US Ignition

Jim Roberts president at U.S. Ignition, began his 45-year career in the burner and heat recovery industry focused on heat treating specifically in 1979. He worked for and helped start up WB Combustion in Hales Corners, Wisconsin. In 1985 he joined Eclipse Engineering in Rockford, IL, specializing in heat treating-related combustion equipment/burners. Inducted into the American Gas Association’s Hall of Flame for service in training gas company field managers, Jim is a former president of MTI and has contributed to countless seminars on fuel reduction and combustion-related practices.

For more information: Contact Jim Roberts at jim@usignition.com.

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From Furnace To Your Front Door: A Morning in Heat Treatment

/ HARDENING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT TECH, NITROCARBURIZING TECHNICAL CONTENT

Heat treatment impacts almost every facet of our lives, yet few people are aware of how important this practice is to a modern way of living. Heat treatment is a process which changes the microstructure of a metal, such as hardening, carburizing, tempering, and many others.

When a metal is formed, it undergoes heat treatment in order to make it longer lasting, change its structure so that it becomes harder or softer, or reduce the tendancy toward cracking which can form during manufacturing. To help us appreciate the impact of heat treatment on our daily lives, Tiffany Ward, daily editor for Heat Treat Today, has prepared this illustrative post.

Breakfast of Champions

You wake up in the morning and roll yourself out of bed, greeting a foggy sunrise through the window. You stumble to the kitchen to fire up your cast iron skillet.

Cast iron contains a minimum of 2% carbon

At one time, that same cast iron skillet lived a provincial life, known as simply: iron. Cast iron is made from iron with greater than 2% carbon, which is in the form of graphite. When that iron was “cast,” it was melted at a high temperature, and once cooled, it transformed into a very stable material that heats and cools uniformly. Perfect for your sunny-side-up eggs.

At the foundry, someone poured the molten metal into a mold to form the exact shape your pan is in today, and then it underwent numerous heat treat processes: annealing, normalizing, tempering, and even graphitizing (a process of converting carbon into graphite). The particular processes the skillet underwent depend upon the chemistry of the cast iron.

Almost all cast iron has carbon and nitrogen added to its surface in a process called ferritic nitrocarburizing plus post-oxidation. This heat treatment gives a shallow surface layer to the pan for better wear resistance. The skillet is heated up between around 1550°F and 1650°F inside a protective atmosphere of Endothermic gas. Endothermic gas is a generated heat treat atmosphere. It is made up of approximately 40% hydrogen, 40% nitrogen, and 20% carbon monoxide. The Endothermic gas is enriched with both a hydrocarbon gas (i.e., natural gas or propane) and ammonia so that carbon and nitrogen can be added to the iron.

There are a variety of different furnaces that can be used for ferritic nitrocarburizing. Box, pit, and tip-up furnaces are used due to their large capacity. For cast iron skillets, one common choice is the pit furnace — a cylindrical furnace typically located in the floor of a factory. Pit furnaces can hold a lot of heavyweight items, making them a good fit for the cookware now resting on your stove.

Figure Source: Herring, Daniel H., Atmosphere Heat Treatment Volume 1, BNP Media II, LLC, 2014. 

Technical Resource: An Overview of Case Hardening: Which Is Best for Your Operations?

Technical Resource: Nitriding and Nitrocarburizing: The Benefits for Surface Treatment

It Cuts Like a Knife

You pull a knife out of your drawer and begin slicing an apple. The blade reflects a beam of sun from the window, but it isn’t your best knife. You’ve noticed that some of your knives are sharper and can resharpen more easily than others; this is because of the quality of the original material used and the heat treatment process employed in manufacturing the knife.

Perhaps the knife you chose to use today was made from high carbon steel such as 1095. The blade was heat treated using a process of hardening, quenching, and tempering. After the blade was formed, it entered a continuous mesh-belt furnace and was quenched in either oil (in the case of a 1095 steel), or in the case of stainless steel or tool steel, cooled in still air.

Source: Dan Herring, The HERRING GROUP, Inc.
Figure: Batch integral-quench furnace system installation (courtesy of AFC-Holcroft). Dan Herring, The HERRING GROUP, Inc.

At the same time of hardening and quenching, the handle was joined to the blade in a process called brazing. The entire knife was heated up to an austenitizing temperature and rapidly cooled in the quenching process, giving it a particular hardness level.

The hardening process can be performed in a vacuum furnace or an atmosphere furnace. The atmosphere is typically nitrogen or, more commonly, a nitrogen/hydrogen mixture. Another option is nitrogen plus dissociated ammonia (dissociated ammonia is 75% hydrogen, 25% nitrogen).

A typical temperature for the heat treatment of high carbon 1095 steel knives is 1475ºF. Stainless steels are run at higher temperatures, typically in the range of 1800º/1950ºF and tool steels even higher, to around 2200ºF.

Technical resources: Ask the Heat Treat Doctor®: How Does One Determine Which Quench Medium To Use?

Technical Resource: Heat Treat Radio #105: Lunch and Learn: Batch IQ Vs. Continuous Pusher, Part 2

Time to Look Pretty

After breakfast you head to the bathroom. You are anxious to rid yourself of unshaven scruff, carefully running a razor over your face. The razor blades were hardened and tempered for sharpness, so that you get a smooth, clean shave. 

Like knives, razor blades are hardened and are made of a medium to high carbon steel. Unlike knives, they are hardened in a continuous strip form. Envision all of your razor blades as a single, thin strip, run continuously through a furnace to heat and cool them. The blade is heated in a protective atmosphere as it runs through the furnace. On one end of the furnace is a reel that coils the strip and at the other end is an un-coiler.

Continuous style furnaces have alloy tubes inside of them that are very small in diameter, typically one inch, which run the entire length of the furnace. As the razor strip is run through the tube it is exposed to an atmosphere of nitrogen and hydrogen, typically with 3% hydrogen, to protect the razor blade surface from oxidation. Once heated, the blade enters cooling either by surrounding the tube with water or by blowing forced air on the tubes.

A process called tempering follows hardening and quenching. When you harden a material you make it stronger, but less ductile, so there is a concern that the razor blade might break. The tempering process improves ductility, removing some of the hardness but improving flexibility.

Dan Herring, The Heat Treat Doctor®, describes the balancing act this way: “On one end of the teeter totter, metallurgically, are strength properties and on the other side of the teeter-totter are ductility properties. It’s always a challenge to properly balance the teeter-totter. If you get the hardness too high, what happens to the ductility? It’s very low. As a result, the material is super hard but may crack easier. On the other hand, if ductility is too high, the material is super flexible so that it can bend like a branch of a tree in the wind, but it has little strength. You need a balance of strength and ductility in all heat treated products, which is accomplished in part by proper tempering.” 

Technical Resources: Tempering: 4 Perspectives — Which makes sense for you?

Technical Resources: Ask The Heat Treat Doctor®: What Are the Differences Between Intergranular Oxidation (IGO) and Intergranular Attack (IGA)? 

Wake Up and Smell The Heat treatment

Our lives are touched by heat treatment at every turn. Highly technical processes play their role in the formation of even the most common household items. While heat treatment may seem to some a niche industry, its impact on everyday life is ubiquitous.

A special note of thanks to Dan Herring, The Heat Treat Doctor®, for his insights and contributions which informed this post.

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