quenching

Induction Through Heating + Intensive Quenching: A “Green Ticket” for Steel Parts

/ CARBURIZING TECHNICAL CONTENT, FEATURED NEWS, INDUCTION HEATING EQUIPMENT TECHNICAL CONTENT, INDUCTION HEATING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT, QUENCHING TECHNICAL CONTENT

OCOn site at heat treat operations, gas-fired furnaces can be a significant source of carbon emissions. But depending on the desired heat treatment, an alternative approach that combines induction through heating and intensive quenching could be the “green ticket.” Learn about the ITH + IQ technique and discover how certain steels may benefit from this approach.

This Technical Tuesday article was composed by Edward Rylicki, Vice President Technology, and Chris Pedder, Technical Manager Heat Treat Products and Services, at Ajax TOCCO Magnethermic Corp., and Michael Aronov, CEO, IQ Technologies, Inc. It appears in Heat Treat Today's May 2023 Sustainable Heat Treat Technologies print edition.

Introduction

Chris Pedder,
Technical Manager Heat Treat Products and Services, Ajax TOCCO Magnethermic Corp.
Source: Ajax TOCCO Magnethermic Corp.

Induction heating is a green, environmentally friendly technology providing energy savings and much greater heating rates compared to other furnace heating methods. Other advantages of induction heating include improved automation and control, reduced floor space, and cleaner working conditions. Induction heating is widely used in the forging industry for heating billets prior to plastic deformation. Induction heating is also used for different heat treatment operations such as surface and through hardening, tempering, stress relieving, normalizing, and annealing. However, the amount of steel products subjected to induction heating in the heat treating industry is much less compared to that processed in gas-fired furnaces.

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Gas-fired heat treating equipment is a major source of carbon emissions in the industry. As shown in Reference 1, induction through heating (ITH) followed by intensive quenching (IQ) (an “ITH + IQ” technique) eliminates, in many cases, the need for a gas-fired furnace when conducting through hardening and carburizing processes — the two most widely used heat treating operations for certain steel parts. Eliminating gas-fired furnaces will result in significant reduction of carbon emissions at on-site heat treat operations.

Dr. Michael Aronov,
CEO, IQ Technologies, Inc.
Source: Ajax TOCCO Magnethermic Corp.

The goal of this article is twofold: 1) to evaluate carbon emissions generated during through hardening of steel parts and carburizing processes when conducted in gas-fired furnaces, and 2) to discuss how these emissions can be reduced to zero using the ITH + IQ process.

Evaluation of Carbon Emissions for Through Hardening and Carburizing Processes

Ed Rylicki,
Vice President Technology, Ajax TOCCO Detroit Development & Support Center
Source: Ajax TOCCO Magnethermic Corp.

Most through hardening and carburizing operations for steel parts are conducted in batch and continuous integral quench gas-fired furnaces. Assumptions made for evaluating CO2 emissions produced by a typical integral quench furnace are presented in Table 1. Note: The values of carbon emissions presented Table 1 are conservative since they don’t consider the amount of CO2 produced by furnace flame screens and endothermic gas generators used to provide a controlled carburizing atmosphere in the furnace. Also, it’s assumed that the furnace walls are already heated through when loading the parts, so there are no heat losses associated with the thermal energy accumulated by the furnace walls.

Table 1. Assumptions for calculating of carbon emissions by integral quench furnace
Source: Ajax TOCCO Magnethermic Corp.

Emissions Generated During the Through Hardening Process

A furnace time/temperature diagram for the through hardening process considered is presented in Figure 1. Carbon emissions Ehard produced by the furnace considered during heating of the load to the austenitizing temperature prior to quenching are calculated by using the following equation,

 

(Equation 1)
Ehard = k • Qhard

where:

■ k = the emission coefficient (equal to 0.050 • 10-3 kg per 1 kJ of released energy when burning natural gas (see Reference 2)
■ Qhard = thermal energy required for heating up the above load from ambient to the austenitizing temperature

A value of Qhard is calculated by the equation below,

(Equation 2)

Qhard = M • C • (Ta -To) / Eff = 1,135 • 0.56 • (843 - 20) / 0.65 = 0.805 • 106kJ

where:

■ M = load weight, kg
■ C = steel specific heat capacity (kJ/kg°C)
■ Ta = part austenitizing temperature (°C)
■ To = part initial temperature (°C)
■ Eff = furnace thermal efficiency (a ratio of the furnace thermal losses to the gross heat input)

From equations (1) and (2), the amount of carbon emissions produced by the above furnace during one hardening operation is 40.2 kg. To determine an annual amount of carbon emissions, calculate the number of hardening cycles per year (Nhard) run in the furnace. From Figure 1, a duration of one hardening cycle is 4 hours (3 hours for austenitizing of the parts plus 1 hour for quenching the parts in oil and unloading/loading the furnace). Thus, Nhard is equal to:

Nhard = 360 day • 24 hour • 0.85 / 4 hour = 1826

Figure 1
Source: Ajax TOCCO Magnethermic Corp.

Annual CO2 emissions from one integral quench batch gas-fired furnace are 40.2 • 1836 = 73,807 kg, or more than 73 t

Emissions Generated During Carburizing Process

A simplified furnace time/temperature diagram for the carburizing process considered is presented in Figure 2. Carbon emissions (Ecarb) produced by the above furnace during the carburizing process are calculated by the following equation,

(Equation 3)

Ecarb = k • Qcarb

where:

■ Qcarb = a thermal energy expended by the furnace during the carburizing process. A value of Qcarb amounts to two components: 

(Equation 4)

Qcarb = Qcarb1 + Qcarb2

Qcarb in the following equation is:

■ Qcarb1 = energy required for heating up the load to the carburizing temperature
■ Qcarb2 = energy needed for maintaining the furnace temperature during the remaining duration of the carburization process (for compensation of the furnace thermal losses since the parts are already heated up to the carburizing temperature)

A value of Qcarb1 is calculated using equation (2) where the part carburizing temperature Tc is used instead of part austenitizing temperature Ta (see Table 1):

Qcarb1 = 1,135 • 0.56 • (927 – 20) / 0.65 = 0.887 • 106 kJ

A value of Qcarb2 is a sum of the flue gas losses and losses of the thermal energy through the furnace walls by heat conduction. Qcarb2 is evaluated from the following considerations. Since the assumed furnace thermal efficiency is 65%, the furnace heat losses are equal to 35% of the gross heat input to the furnace. Hence, the furnace heat losses Qloss1 during the load heat up period (the first 3 hours of the carburizing cycle, see Figure 2) are the following:

Qloss1 = Qcarb1 • 0.35 = 0.887 • 106 • 0.35 = 0.31 • 106 kJ.

The furnace heat losses during the remaining 8 hours of the carburizing cycle Qloss2 are proportionally greater and are equal to:

Qloss2 = Qloss1 • 8 hr /3 hr = 031 • 106 • 8 /3 = 0.827 • 106 kJ

Thus, the total amount of the thermal energy expended by the furnace during the carburizing cycle is Qcarb = 0.887 • 106 + 0.827 • 106 = 1.71 • 106 kJ. The total amount of the CO2 emissions from carburizing of the load in the furnace considered according to equation (3) is: Ecarb = 0.050 • 10-3 • 1.71 • 106 = 85.7 kg. To determine an annual amount of carbon emissions from one carburizing furnace, calculate the number of carburizing cycles run in the furnace per year. Per Figure 2, a duration of one carburizing cycle is 12 hour (1 hour for the furnace recovery plus 10 hour for carburizing of parts at 927°C plus 1 hour for quenching parts in oil and for unloading and loading the furnace). Thus, the number of carburizing cycles per year Ncarb is:

Ncarb = 360 day • 24 hr • 0.85 / 12 hr = 612

Figure 2
Source: Ajax TOCCO Magnethermic Corp.

Annual CO2 emissions from one integral quench batch carburizing furnace is about 85.7 • 612 = 52,448 kg, or more than 52 t.

Reducing Carbon Emissions Using the ITH + IQ Process

Reference 1 presents results of two case studies of the ITH + IQ process on automotive input shafts and drive pinions. The study was conducted with a major U.S. automotive part supplier. A two-step heat treating process was used for the input shafts, consisting of batch quenching parts in oil or polymer using an integral quench gas-fired furnace for core hardening followed by induction hardening. This two-step method of heat treatment is widely used in the industry for many steel products. It provides parts with a hard case and tough, ductile core.

Substituting the “ITH + IQ” method for the two-step heat treating process not only eliminates the batch hardening process, but also requires less alloy steel for the shafts that don’t require annealing after forging. Thus, in this case, applying the ITH + IQ technique eliminates two furnace heating processes for the input shafts, resulting in the reduction of the CO2 emissions to zero for the shafts’ heat treatment. Per client evaluation, as mentioned in Reference 1, the hardness profile in the intensively quenched input shafts was similar to that of the standard shafts. Residual surface compressive stresses in the intensively quenched shafts were greater in most cases compared to that of the standard input shafts, resulting in a longer part fatigue life of up to 300%.

Per Reference 1, the environmentally unfriendly  carburizing process can be fully eliminated in most cases for automotive pinions when applying the ITH + IQ method and using limited hardenability (LH) steels that have a very low amount of alloy elements. A case study conducted for drive pinions with one of the major U.S. automotive parts suppliers demonstrates the intensively quenched drive pinions met all client’s metallurgical specifications and passed both the ultimate strength test and the fatigue test. It was shown that the part’s fatigue resistance improved by about 150% compared to that of standard carburized and quenched in oil drive pinions. In addition, distortion of the intensively quenched drive pinions is so low that no part straitening operations were required.

Conclusion

Coupling Ajax TOCCO’s induction through heating method with the intensive quenching process creates a significant reduction of CO2 emissions produced during heat treatment operations for steel parts. For the through hardening process, eliminating just one batch integral quench gas-fi red furnace will reduce carbon emissions by more than 73 ton per year. For the carburizing process, eliminating just one batch carburizing furnace will reduce carbon emissions by more than 52 ton per year. Note that for continuous gas-fired furnaces, the carbon emission reduction will be much greater due to higher continuous furnaces production rates (hence a much higher fuel consumption).

Per our experience, the ITH + IQ process can be applied to at least 20% of the currently through-hardened and carburized steel parts. Per two major heat treating furnace manufacturers in the U.S., there are thousands of atmosphere integral quench batch and continuous furnaces in operation in the U.S. That means hundreds of gas-fired heat treating furnaces can be potentially eliminated, drastically reducing carbon emissions in the U.S., supporting a lean and green economy.

 

References

[1] Michael Aronov, Edward Rylicki, and Chris Pedder, “Two Cost-Effective Applications of Intensive Quenching Process for Steel Parts,”Heat Treat Today, October 2021, https://www.heattreattoday.com/processes/quenching/quenching-technical-content/two-cost-effective-applications-for-intensive-quenching-of-steel-parts/.

[2] U.S. Energy Information Administration.

About the Authors:

Ed Rylicki has been in the induction heating industry for over 50 years. He is currently Vice President Technology at Ajax TOCCO Detroit Development & Support Center in Madison Heights, Michigan.

Mr. Chris Pedder has over 34 years of experience at Ajax Tocco Magnethermic involving the development of induction processes in the heat treating industry from tooling concept and process development to production implementation.

Dr. Michael Aronov has over 50 years’ experience in design and development of heating and cooling equipment and processes for heat treating applications. He is CEO of IQ Technologies, Inc. and a consultant to the parent company Ajax TOCCO Magnethermic.

For more information: Contact info@ajaxtocco.com or 800.547.1527

 

 

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

 

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Heat Treatment System to Expand Specialty Automotive Fastener Manufacturer’s Capabilities

/ ATMOSPHERE AIR FURNACES NEWS, AUTOMOTIVE HEAT TREAT, FEATURED NEWS

HTD Size-PR LogoOne of the world’s largest producers of high volume, specialty automotive fasteners based in Italy has awarded two contracts to Canadian heat treat supplier in order to expand their manufacturing capabilities with a mesh belt fastener heat treatment system.

The two systems being supplied represent CAN-ENG Furnaces International Ltd. (CAN-ENG) high-capacity line of mesh belt fastener heat treatment systems.

The client returned to the furnace manufacturer in order to receive a furnace with proven low energy consumption, reduced part mixing, reduced part damage potential, and high uptime productivity when compared to conventional cast link furnace designs.

The system will include: computerized vibratory loading system, rotary phosphate removal washer, mesh belt hardening furnace, oil quench system, post quench wash system, mesh belt temper furnace, soluble oil, and part containerization system.

CAN-ENG Furnaces International Ltd. (CAN-ENG) high-capacity mesh belt fastener heat treatment system

These fully integrated systems will feature CAN-ENG’s Process Enhancement Technology – PET™ System (Supervisory Control and Data Acquisition System) which provides the client with complete product traceability through the critical thermal process, process data collection, historical event archiving, process variable trend monitoring, scheduling optimization, and energy consumption features which are unique to CAN-ENG systems.

These new systems will be commissioned to the EU in early 2022.

Heat Treatment System to Expand Specialty Automotive Fastener Manufacturer’s Capabilities Read More »

Heat Treating With Salts

/ FEATURED NEWS, MANUFACTURING HEAT TREAT NEWS, QUENCHING TECHNICAL CONTENT

OC

Jerry Dwyer
Market Manager 
Hubbard-Hall

“Successful heat treating begins by understanding the make-up of the steel that is to be treated.”

Heat Treat Today’s Technical Tuesday feature provides an overview of the heat treatment process and the benefits wrought from heat treating in salt baths. The article also illuminates details to understand part composition and the austempering and quenching process as a whole.

The author of this Original Content article, Jerry Dwyer, market manager at Hubbard-Hall, has previously written for Heat Treat Today on the topic of polymer quenchants as an alternative to water and oil quenching. Read more here.

Heat treating is a process in which metal is heated to a predetermined temperature and then cooled in a particular manner to alter its internal structure for obtaining a desired degree of physical, mechanical and metallurgical properties. The purpose is to obtain maximum strength (i.e., increase the metal’s hardness) and durability in the material.

Numerous industries utilize heat treated parts, including those in the automotive, aerospace, information technology, and heavy equipment sectors. Specifically, manufacturers of items such as saws, axes, cutting tools, bearings, gears, axles, fasteners, camshafts, and crankshafts all rely on heat treating to make their products more durable and to last longer.1

The heat treating processes require three basic steps:

  1. Heating to a specified temperature.
  2. Holding at that temperature for the appropriate amount of time.
  3. Cooling according to prescribed methods.

Understanding the Part Material

According to the ASM International’s Heat Treating Society, about 80 percent of heat treated parts are made of steel, such as bars and tubes, as well as parts that have been cast, forged, welded, machined, rolled, stamped, drawn, or extruded.1

SAE Designation. (Image source: Jerry Dwyer. Reference source #3.)

Successful heat treating begins by understanding the make-up of the steel that is to be treated. The American Iron and Steel Institute (A.I.S.I.) and the Society of Automotive Engineers (S.A.E.) utilize a four-digit system to code various types of steel used in manufacturing. The alloying element in the AISI specification is indicated by the first two digits, and the amount of carbon in the material is indicated by the last two digits. The first digit represents a general category of the steel groupings, meaning that 1xxx groups within the SAE-AISI system represent carbon steel. The second digit represents the presence of major elements which may affect the properties of steel; for example, in 1018 steel the zero in the 10xx series depicts no major secondary element. The last two digits indicate the percentage of carbon concentration. SAE 1018 indicates non-modified carbon steel containing 0.18% of carbon, while SAE 5130 indicates a chromium alloy steel containing 1% chromium and 0.30% carbon.

Carbon steel has a main alloying constituent of carbon in the range of 0.12% to 2.0%. Plain carbon steel is usually iron with less than 1% carbon, plus small amounts of manganese, phosphorous, sulfur and silicon. Carbon steel is broken down into four classes based on carbon content:

  • Low Carbon Steel: up to 0.3% carbon content
  • Medium Carbon Steel: 0.3 – 0.6% carbon content
  • High Carbon Steel: 0.6 – 1.0% carbon content
  • Ultra-High Carbon Steel: 1.25 – 2.0% carbon content

The Austempering and Quenching Process

Austempering is one of several heat treatments that is applied to ferrous metals and is defined by both the process and the resultant microstructure of the work. In steel, it produces a bainite (or a plate-like) microstructure.

 

Typical Austempering Heat Treatment Cycle in Ductile Iron

When heated to temperatures below 730°C (1346°F), the pure metal iron has a body-centered cubic structure; if heated above this temperature, the structure will change to a face-centered cubic. On cooling, the change is reversed, and a body-centered cubic structure is once more formed. The importance of this reversible transformation lies in the fact that up to 2.0% carbon can dissolve in a face-centered cubic, forming what is known as a “solid solution.” While in a body-centered cubic iron state, no more than 0.02% carbon can be dissolved this way. The solid solution formed when the carbon atoms are absorbed into the face-centered cubic structure of iron is called austenite.

 

Austempering Process Steel Structuring

When quenched, carbon is precipitated from austenite not in the form of elemental carbon (graphite), but as the compound iron carbide Fe3C, or cementite. Like most other metallic carbides, this substance is usually very hard; as the amount of carbon increases, the hardness of the cooled steel will also increase.

The temperature of the quench tank is set so that the material is rapidly cooled down at a rate fast enough to avoid transformation to intermediate phases such as ferrite or pearlite and then held at a temperature that falls within the bainite region but staying above the martensitic phase. The bainitic microstructure that is formed as a result of austempering imparts high ductility, impact strength, and wear resistance for a given hardness; a rifle bolt was one of the first applications for this process.

The salt quench also provides low distortion of work with repeatable dimensional response. The materials have increased fatigue strength and is, in general, more resistant to hydrogen and environmental embrittlement.

Heat Treat with Salt Baths

Salt bath heat treatment is a heat treatment process comprising an immersion of the treated part into a molten salt, or salts mixture.2 There are numerous benefits of heat treatment in salt baths, the most prevalent is that they provide faster heating. A work part immersed into a molten salt is heated by heat transferred by conduction (combined with convection) through the liquid media (salt bath).2 The heat transfer rate in a liquid media is much greater than that in other heating mechanisms, such as radiation or convection through a gas.2

Using salt baths also helps with a controlled cooling conditions during quenching. In conventional quenching operation, typically either water or oil are used as the quenching media and the high cooling rate provided by water/oil may cause cracks and distortion. Cooling in molten salt is slower and stops at lower temperature and avoids may of the pitfalls associated with a faster quench.2

Salt baths also provide low surface oxidation and decarburization, as the contact of the hot work part with the atmosphere is minimized when the part is treated in the salt bath.2 There are additional advantages to salt heat treat:

  • Wide operating temperatures: 300°F -2350°F
  • Most of the heat is extracted during quenching by convection at a uniform rate.
  • Salt gives buoyancy to the work being processed to hold work distortion to a minimum.
  • Quench severity can be controlled or manipulated by a greater degree by varying temperature, agitation and water content of the salt.
  • Excellent thermal and chemical stability of the salt means that the only replenishment required is due to drag-out losses.
  • Nonflammable salt poses no fire hazard.
  • Salt is easily removed with water after quenching.

References:

  1. “What is Heat Treating?” ASM International. https://www.asminternational.org/web/hts/about/what-is
  2. Dmitri Kopeliovich, “Salt Bath Heat Treatment,” SubsTech. https://www.substech.com/dokuwiki/doku.php?id=salt_bath_heat_treatment
  3. AISI/SAE Steel and Alloy Designation System, The Engineering Toolbox. www.engineeringtoolbox.com

 

 

About the Author: Jerry Dwyer is Hubbard-Hall’s market manager for product groups pertaining to heat treating, phosphates and black oxide. To learn more or get in touch, please visit Hubbard-Hall’s website.

 

 

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How CQI-9 Compliant Quench Oil Analysis Can Aid in Proper Care of Quench Oil

/ AUTOMOTIVE HEAT TREAT, FEATURED NEWS, QUENCHING TECHNICAL CONTENT

OCCQI-9 compliance demands adherence to the standards for the purpose of excellence in automotive heat treating. Poorly maintained quench oil can cost heat treaters in many areas. 

In this Heat Treat Today Technical Tuesday feature, Greg Steiger, senior key account manager at Idemitsu Lubricants America, shares how costly quench oil issues can be addressed through proper adherence to the CQI-9 quench oil testing protocols. Let us know if you’d like to see more Original Content features by emailing editor@heattreattoday.com.

Greg Steiger
Sr. Key Account Manager
Idemitsu Lubricants America

Introduction

A poorly maintained quench oil can cost a heat treater in more ways than simply the cost of having to replace the oil.  The costs can quickly expand to include those associated with poor quality.  For example, costs associated with part rejects, or rework and downstream costs for shot blasting, or third-party inspection are often the cause of poor quench oil maintenance.  Dirty or poorly maintained oils can affect part cleanliness, surface hardness, and surface finish.  For instance, it is well known that a heavily oxidized oil may create surface stains that must be shot blasted to remove.  High molecular weight sludge or excessive water can create surface hardness issues.  Many of these issues can be addressed through proper adherence to the quench oil testing protocols established by CQI-9.

How can CQI-9 help?

CQI-9 is designed as a tool to help heat treaters produce consistent parts.  Using a CQI-9 compliant quench oil analysis can also be a very powerful tool in a heat treaters tool kit.  Just as the level of carburization is influenced by the carbon potential of a carburizing atmosphere, the cooling speed of the oil influences microstructure formation and microstructure composition along with mechanical properties such as hardness as well as tensile and yield strength. Furthermore, the cooling speed is dependent upon the viscosity of the oil, the amount of sludge, moisture level, and oxidation of the oil.  All of these are tested on a regular basis under the requirements of CQI-9, ISO TS 16949, and most quality systems adopted by modern heat treaters.  All of the tested parameters required under CQI-9 will be addressed individually later in this paper.

What is CQI-9?

The member companies of the Automotive Industry Action Group (AIAG) encompassing automotive manufacturers and their Tier I suppliers have enacted an industry heat treating standard called CQI-91.  This standard was originally a standalone standard designed and adhered to primarily by North American OEMs and Tier I suppliers as a quality tool to create consistent documented processes within the heat treating industry with the goal of producing consistent reproducible results.  Since that first implementation of CQI-9, the standard has now been incorporated into the ISO TS 16949 standard and is now adhered to by most automotive OEMs and their Tier I suppliers.  The full range of management responsibilities, material handling, and equipment operations of the CQI-9 standard is beyond the scope of this paper.   Instead we will be discussing the used quench oil analysis requirements of CQI-9, why the tests are required, and how heat treaters need a CQI-9 compliant quench oil analysis to properly care for their quench oils.

Utilizing a compliant CQI-9 analysis and the supplier provided operating parameters for the CQI-9 required tests is the first step in the proper care of a quench oil.

CQI-9 Compliant Analysis

Most quench oil suppliers provide a quench oil analysis.  Although the quench oil supplier may provide a quench oil analysis, for the analysis to be CQI-9 compliant the analysis must contain the following tests or their equivalent:

  • Water content; ASTM D6304
  • Suspended solids; ASTM D4055
  • Viscosity; ILASD509
  • Total acid value; ASTM D664
  • Flash point; ASTM D92
  • Cooling curve; JIS K2242

The frequency of the above testing must be a minimum of semiannually.  A more frequent sampling interval does not violate CQI-9.  In fact, the more often a quench oil is analyzed, the easier it is to use the quench oil analysis as a tool in the proper care of a quench oil.  It is important to note that the CQI-9 standard does not prescribe specific test methods be used in the above testing; however, they must be performed to a traceable standard.  The CQI-9 standard only states that the above values, along with a cooling curve, must be reported.   The following sections will describe each test in a CQI-9 compliant analysis.

Water Content

Everyone knows water in a quench oil can be have catastrophic safety and performance consequences.  However how much water is too much?  That is a question that is difficult to answer.  The answer depends on a variety of factors such as the quench oil used and all of the variables associated with a furnace atmosphere.  A general rule of thumb when it comes to water levels is to keep the water level below 200PPM.  At levels above 200PPM of water, uneven cooling begins to occur.2  It is important to remember a quench oil is not a pure homogenous fluid.   Samples taken at various places throughout the quench tank will be similar but will also have differences.  These differences will include water and solids levels.  Therefore, in areas where the water content exceeds the 200PPM level, uneven cooling will begin.  Parts coming into contact with this “localized” quench oil with high water can potentially begin to crack, have a high surface hardness, or have staining problems.  Yet parts in other areas of the load continue to behave normally.  For this reason, and also because water is much heavier than oil, it is imperative the oil be under agitation. In addition to the potential uneven cooling issues high water may create, a high level of water can also influence the rate of oxidation in an oil.

Suspended Solids

Because solids are typically denser and more viscous than liquids they do not have the same heat transfer properties as a liquid. Due to the inequality of heat transfer capacities between liquids and solids, it is very important to keep the solids level, especially high molecular weight sludge, at a minimum.  Sludge reacts in an opposite manner of water.  Where water can increase quench speed, high molecular weight sludge will decrease quench speed through uneven cooling.2 The result of the uneven cooling from sludge is typically seen in soft surface microstructures or soft surface hardness.  Also, like water, sludge is heavier than oil and the lack of homogeneity in the oil means having proper agitation is paramount when sampling.

Viscosity

Changes in viscosity can lead to both faster quench rates and slower quench rates.  As the quench oil is used in the quench process, it undergoes thermal degradation.3  This degradation process can be seen when the oil becomes thinner or less viscous.  During this process, a small portion of the base oil and a small amount of the quench oil additives undergo a process called thermal cracking.  In this process, heavier molecules are broken into smaller molecules through the use of heat. This thermal cracking creates lighter less viscous oil from heavier oils.  The newer lighter viscosity of the quench oil can potentially lead to changes in the quench speed of the oil.  These changes can have an impact on the microstructure, case depth, core hardness, and surface hardness on the quenched parts.

As an oil is subjected to the high temperatures of a quenching operation, oxidation is a natural occurrence in the oil.    As the oil oxidizes it will begin to increase in viscosity until it reaches the point of forming an insoluble sludge.  Therefore, an increase in viscosity typically means the oil is oxidizing.  Just as an oil that becomes thinner and less viscous may have a change in cooling properties, an oil that becomes thicker and more viscous may see a change in cooling performance.   A thicker oxidized quench oil may affect surface hardness, microstructure, case depth, and core hardness.  In severe cases of oxidation staining may result.  Such stains typically require post quench and temper processing such as shot blasting.

Total Acid Value

The Total Acid Value, or TAV, is a measure of the level of oxidation in a quench oil.  The amount of oxygen in a quench oil cannot be measured without a sophisticated laboratory analysis.  However, the formation of organic acids within a quench oil can be easily determined via a titration method.  It is well understood that these organic acids are the precursors in a chain of chemical reactions that will eventually form sludge. As the TAV increases so will the levels of oxidation, and in turn, the amount of sludge will also increase.  Consequently, as the TAV increases, the amount of staining due to oxidation may increase.  The cooling properties of the oil may decrease due to the increased sludge formation as well.  Figure #1 shows an example of how the acid value increases the viscosity of a quench oil due to the formation of polymeric sludge in the quench oil.2

Figure #1. Acid number vs kinematic viscosity for Daphne Hi Temp A

 

Flash point

The flash point of a quench oil is another check to ensure the safety of the quench oil user.   As oil thermally cracks, the heavier base oils become not only lighter in viscosity, but their flash points also decrease.  If left unchecked, the decrease in flash point could result in a higher risk of fire.   In addition to serving as a watchdog against the results of excessive thermal cracking, a flash point is also a safeguard against human error and adding the wrong quench oil to a quench tank.  High temperature oils typically have a higher flash point than conventional oils.  An increase in flash point, along with no change in TAV, and an increase in viscosity could indicate a contamination issue between oils has occurred.

Cooling curve

There are many different methods of running a cooling curve. Many Asian suppliers of quench oil will use the Japanese Industrial Standard (JIS) K 2242.  European suppliers will use the ISO 9950 and North American suppliers rely on the ASTM D 6200 method.  All of these standards measure the same basic property, the ability of an oil to reach martensite formation.  However, they differ in one basic item.  The JIS K-2242 and methods used in China and France use a 99.99% silver probe that is smaller than the size of the Inconel probe used in the ASTM and ISO methods of Europe and North America.  Because of this difference, it is important to note that cooling curves and cooling rates between the methods should not be compared.  Figure # 2 shows the comparison between the two probes and their dimensions.

Figure # 2. ASTM D-6200/ ISO- 9950 and JIS K 2242 quenchometer probes^2
ISO/ASTM Inconel probe 12.5mm x 60mm.
JIS K 2242 Silver probe 10mm x 30 mm

 

In addition to comparing the cooling curve against the standard for the quench oil used, the Grossman H value should also be calculated and used as an indicator of cooling performance.  Unlike the old GM nickel ball test that tracked the time to cool a 12mm nickel ball to 352°C, the Grossman H value measures the severity of the quench6.

In using the Grossman H value, the lower the value, the slower and less severe the quench.   For use as a rough guide in comparing the quench speed in seconds to the Grossman H value measured in cm-1 the table below can be used.

Table #1

For example, air has an approximate H value of 0.01 cm-1 and water has an approximate H value of 0.4 cm-1 compared to oil with an approximate H value of ___ cm-1

The calculation used to determine the Grossman H factor has historically been:

H=h/2k

Where h is the heat transfer coefficient of the part when measured at the surface of the part and k is the thermal conductivity of the steel.  Typically the heat transfer coefficient is measured at 705°C. A steel’s thermal conductivity does not typically change according to alloy composition or temperature.  Therefore, the Grossman H value is proportional to the heat transfer coefficient of the part.

Interpreting a CQI-9 quench oil analysis

Table #2

Discussion

In examining the test parameters for CQI-9, it becomes apparent that many of the test results should be compared with other test results.  For example an increase in the amount of sludge or solids should also increase the viscosity of the quench oil.  As the sludge increases, the level of oxidation increases, and therefore, the level of organic acids formed in the quench oil should be increasing the TAV.  Finally, as the sludge increases, the cooling property of the quench oil should decline as indicated in the lower H value.

Figure #3. Total Acid Value (TAV) and Grossman H value

 

Likewise, as the flash point decreases the amount of thermal cracking is increasing, which should reduce the viscosity and thereby increase the H value and the overall cooling speed of the quench oil. Conversely, if the test parameters are not working in concert with each other, there may be other issues going on within the quench oil.  For instance, an increase in the water content can be detected before the increased water levels begin the oxidation process thereby increasing the TAV.  Or a viscosity change without a change in other parameters could be an addition of the wrong quench oil to the quench tank.  The graph below for Idemitsu Daphne Hi Temp A helps illustrate this point.

Figure #4. Graph for Idemitsu Daphne Hi Temp A demonstrating viscosity change

In the graph above, it can be seen when the water H value increases and the viscosity remains stable, the likely explanation is an increase in water.   When both the H value and viscosity decrease, additive consumption is the most likely reason.  Likewise, when the viscosity increases and the H value decreases, the formation of sludge from oxidation is the culprit.

Having test parameters that work in conjunction with each other is only beneficial if sample frequencies are often enough.  While CQI-9 only stipulates a semi-annual sampling frequency, the conditions of a quench tank can change in very short order.  There are the obvious changes when water is added to the tank.  However, many of the changes are more subtle, and left unchecked over time can create potential costly solutions such as a partial dump and recharge of the quench tank, poor part quality, or an increase in downstream processing such as shot blasting.  For this reason, many quench oil suppliers request a minimum of quarterly sampling.  In addition, if a sample is missed on a quarterly sample frequency, there is still time to sample the quench tank and remain in compliance with CQI-9.

Conclusion

Over time the condition of a quench oil will change and corrective measures will be needed to bring the quench oil back into the suggested supplier’s operating parameters.   The chart below helps understand what some of the methods need to be.

With proper care and maintenance, a quench oil can last a very long time.  A conventional oil should last 10 to 15 years or longer while a marquench oil should last seven to 10 years. The proper care of a quench is simple and straight forward.  A quality quench oil should not need the use of additives to improve oxidation resistance or quench speed. Simply adding enough fresh virgin oil to replace the oil that is being dragged out through normal operations should replenish the oxidation protection and quench speed to within the normal operating parameters. The table below offers recommendations for treating out of normal operating parameters for the required CQI-9 tests.

Recommendations for treating out of normal operating parameters for the required CQI-9 tests

Most heat treaters make weekly quench oil additions to their quench tanks.  The most popular type of filtration system is a kidney loop style where the quench oil is constantly filtered.  There are two basic types of these systems.  They differ in the number of filters used.  For a single filter system, a 25 micron filter is sufficient for quench oil filtration.  In a two-stage filtration system, a 50 micron filter is typically used in the first stage and a 25 micron filter is used in the second stage.  In a two-stage filter, the cheaper 50 micron filter will be replaced more often than the 25 micron filter in the second stage.

Utilizing a compliant CQI-9 analysis and the supplier provided operating parameters for the CQI-9 required tests is the first step in the proper care of a quench oil.  The next basic steps are ensuring there is enough fresh quench oil available for regular additions to replace the oil that is lost through drag out and proper filtration of the quench oil in a constant kidney loop type of a system.  With these steps in place, a quench oil will offer consistent performance for years and will be one less concern heat treaters face in the operation of their furnaces.

 

 

References:

  1. Automotive Industry Action Group, “CQI9 “Special Process: Heat Treatment System Assessment;” AIAG version 3, 10/2011.
  2. Rikki Homma, K. Ichitani, M. Matsumoto, and G. Steiger, “Evaluation and Control Technique of Cooling Unevenness by Quenching Oil,” 2017 ASM Heat Treat Expo, https://asm.confex.com/asm/ht2017/webprogram/Paper43594.html.
  3. G. Steiger, “Preventing the Degradation of Quench Oils in the Heat Treatment Process,” Metal Treating Institute, https://www.heattreat.net/blogs/greg-steiger/2018/10/03/preventing-degradation-of-quench-oils-in-the-heat.
  4. M.A. Grossman and M. Asimov. Hardenability and Quenching. 1940 Iron Age Vol. 107 No.17 Pp 25-29.

 

About the Author:

Greg Steiger is the senior key account manager of Idemitsu Lubricants America for quench products.  Previous to this position, Steiger served in a variety of technical service, research and development, and sales marketing roles for Chemtool, Inc., Witco Chemical Company, Inc., D.A. Stuart Company, and Safety-Kleen, Inc. He obtained a BSc in Chemistry from the University of Illinois at Chicago and is currently pursuing a Master’s Degree in Materials Engineering at Auburn University.  He is also a member of ASM International.

 

 

 

 

(photo source: Free Images at unsplash.com)

 

 

 

 

 

 

How CQI-9 Compliant Quench Oil Analysis Can Aid in Proper Care of Quench Oil Read More »

Tackling Failure Due to Stress Corrosion Cracking by Breaking “a Few Cardinal Rules”

/ AUTOMOTIVE HEAT TREAT, AUTOMOTIVE HEAT TREAT NEWS, FEATURED NEWS, TEMPERING TECHNICAL CONTENT

 

Source: Paulo

 

The heat treating of constant tension bands used by automakers is a complex process, and the challenge posed to a leading heat treating company by a supplier of these bands was to determine how to reduce the risk of failure due to stress corrosion cracking.

“Improving the physical characteristics of metal components often requires fine-tuned treatments that bring them to the brink of destruction. It’s a quirk of metallurgy heat treaters contend with constantly.”

Solving the problem involved, as noted in this case study from Paulo, breaking “a few cardinal rules en route.”

 

Read more: “Case study: Unconventional Treatment Improves Quality of Constant Tension Bands”

Tackling Failure Due to Stress Corrosion Cracking by Breaking “a Few Cardinal Rules” Read More »

Distortion Analysis of Landing Gear During Oil Quench: A Case Study

/ AEROSPACE HEAT TREAT, AEROSPACE HEAT TREAT NEWS, FEATURED NEWS, QUENCHING TECHNICAL CONTENT

Charlie Li

A thermal process modeling company used its heat treatment simulation software to explore oil quench sensitivities on the distortion of a large landing gear made of 300M, a vacuum melted low alloy steel that includes vanadium and a higher silicon composition.

DANTE Solutions, an engineering consulting and software company specializing in metallurgical process engineering and thermal/stress analyses of metal parts and components, was approached to examine local stagnant oil flow and immersion, among other sensitivities, for this critical aerospace component.

Zhichao (Charlie) Li, Ph.D., vice president of DANTE Solutions, was the lead researcher and author of this study.

Case Study

Problem Statement

Part:

3 modes of distortion that are of concern

  • 2.5 meter tall landing gear
  • 0.25 meter main tube diameter
  • AISI 300M material

Problem:

  • Large distortions after oil quenching in the following distortion modes:
    • Bow in XY-Plane
    • Bow in YZ-Plane
    • Straightness of a Blind Hole
  • All distortion modes shown in the figures make assembly of the entire structure very difficult.
  • Immersion into the oil tank is the main focus of the distortion analysis.

Process Description

  • Part is austenitized in pit furnace at 1607°F (875°C).
  • A 45-second step is included for the removal of the landing gear from the pit furnace.
  • 75-second open-air transfer from pit furnace to oil quench tank. The landing gear is immersed into the oil with a speed of 203.2 mm/sec, with the immersion direction shown in the figure. It takes 11.885 seconds to immerse the entire gear in the oil tank.
  • The landing gear is held in the oil for 5 minutes.
  • Tempering not considered, due to negligible effects on distortion.

Temperature (°C), Austenite (fraction), horizontal displacement (mm), and vertical displacement (mm) at the end of the immersion process; section cut, looking inside the part.

Model Description

  • Model contains 281,265 nodes and 258,272 hex elements.
  • 3 surfaces defined for heat transfer boundary conditions.
  • Oil flow stagnation is expected inside the main tube (Inner Surface) and the blind hole.
  • Different thermal boundary conditions are applied to the outer surface and the inner surface, as shown to the right.
  • The blind hole and the inner surface have the same thermal boundary conditions in the baseline model.
  • During immersion, oil enters the blind hole first and then begins to fill up the main tube.
  • In the baseline model, the oil level rising speed inside the bore is assumed to be 20% of the landing gear immersion speed.

 

 

Modeling Approach

  • Define heat transfer coefficients as a function of temperature for the oil tank.
    • Thermocouples placed at various locations on a dummy landing gear, which was
      approximately the same overall dimensions and mass. Improve 300M material data in DANTE material database using dilatometry testing.
  • Improve 300M material data in DANTE material database using dilatometry testing.
  • Perform sensitivity study to determine phenomena critical to distortion modes of interest.
    • Oil flow stagnancy in blind hole during immersion: The more stagnancy, the lower the heat transfer on this surface. Baseline assumed to be the most stagnant. Two faster heat transfer rates examined.
    • Oil flow stagnancy around structural support arm: The more stagnancy, the lower the heat transfer on this surface. Baseline assumed to be least stagnant. Two slower heat transfer rates examined.
    • Oil fill rate of the main tube during immersion into the oil: The slower the oil fills up the main tube, the larger the temperature and phase transformation gradient is in the axial direction of the tube. Baseline assumed the slowest fill rate. Three faster fill rates were examined.
    • Immersion direction: Immersion direction sets up axial temperature/phase transformation gradients and also determines how the main tube is filled. The Baseline immersion direction causes oil to enter through the blind hole first and then into the main tube. Opposite immersion direction is examined, which causes oil to enter the open end of the main tube first.

Blind Hole Quench Rate Sensitivity

Figure 8. Temperature (°C) in the blind hole at the end of immersion for the three cases.

  • Heat transfer is increased in the blind hole during the
    immersion process; all other heat transfer rates
    remain the same as the baseline model during
    immersion.
  • All heat transfer rates are identical to the baseline
    after the part is fully immersed in the oil.
  • Baseline model assumes blind hole heat transfer is
    equivalent to the main tube inner diameter heat
    transfer during and after the immersion process.
  • Rate 2 has a faster heat transfer rate than the baseline.
  • Rate 1 has a faster heat transfer rate than Rate 2.
  • Figure 8 shows a significant difference in temperature between the three cases at the end of the immersion process.
  • Heat transfer rates explored in the blind hole do not contribute
    to the tilting of the blind hole.
  • Figure 9 shows that the angle of the hole is the same, regardless of the quench rate.
  • Modification of the blind hole to increase the heat transfer rate
    in the hole to help improve the straightness of the blind hole is not necessary.
  • Heat transfer rates explored in the blind hole do not contribute significantly to the bow distortion in the XYPlane or the YZ-Plane.
  • Figure 10 shows that the bow distortion is made slightly worse by increasing the heat transfer rate in the blind hole during immersion, but is not significantly worse.
  • Modification of the blind hole to increase the heat transfer rate in the hole to help improve the bow distortion is not necessary.

Figure 9

Figure 10.

Structural Beam Quench Rate Sensitivity

  • Reduced heat transfer of the structural arm is examined.
    • Oil flow stagnancy is assumed to reduce heat transfer rate on arm.
    • 2 slower heat transfer rates compared with baseline.
    • Baseline assumes the same heat transfer rate on the structural arm as on the main tube OD.
  • Figure to the left shows the reduced heat transfer rate surfaces of the structural arm.
  • Rate 1 is slower than Baseline.
  • Rate 2 is slower than Rate 1.
  • Figure below shows the temperature difference in the structural beam at the end of the immersion process.
  • Approximately 212°F (100°C) difference between Baseline and Rate 1
  • Approximately 392°F (200°C) difference between Baseline and Rate 2

 

  • Bow distortion in xy-plane has a non- Distortion of Blind Hole linear response to oil stagnancy around the structural beam.
  • Rate 1 produced the least amount of bow in xy-plane.
  • Baseline produces the greatest amount of bow in xy-plane.
  • Distortion of blind hole has a non-linear response to oil stagnancy around the structural beam.
  • Rate 1 produced the straightest blind hole.
  • Baseline produces the greatest amount of distortion of the blind hole.
  • Bow distortion in yz-plane has no sensitivity to oil stagnancy around the structural beam.
  • The non-symmetric mass near the top of the landing gear has the most influence on the yz-plane bow distortion.

  • Figure 15 shows lower bainite phase fraction at the end of the quenching process.

    Figure 15
  • Slower heat transfer rate of the structural beam results in significantly different amounts of lower bainite.
    • The slower the heat transfer, the more lower bainite formed.
  • Increased amounts of bainite reduce bow distortion in xy-plane, but the response is non-linear.
    • Rate 2 caused slightly more distortion than Rate 1, but less distortion than the Baseline.
  • Increased amounts of bainite reduce distortion of the blind hole, but the response is non-linear.
    • Rate 2 caused slightly more distortion than Rate 1, but less distortion than the Baseline.

Oil Fill Rate in Main Tube Sensitivity

  • The rate at which the oil fills the main tube is critical to the phase transformation timings and the phases formed.
  • The immersion speed of the landing gear is 203.2 mm/sec.
  • Baseline assumes the inside of the tube fills up at 20% of this value (40.64 mm/sec).
  • Three different fill speeds were explored:
    • 50% (101.6 mm/sec)
    • 100% (203.2 mm/sec)
    • 200% (406.4 mm/sec) Assumes pressure build up forces oil up the inside of the tube.
  • Figure 16 compares temperature inside tube at end of immersion for four cases.

Figure 16

 

  • The oil fill rate of the main tube during the immersion process has a very significant effect on all three modes of distortion.

From top left clockwise

  • Bow distortion in yz-plane has a non-linear response to the fill speed (Figure 17)
    • 50% produces the worst bow
    • 100% & 200% are very similar, with 200% slightly worse
  • Bow distortion in xy-plane has a non-linear response to the fill speed (Figure 18)
    • 50% produces the least bow
    • 100% produces the worst bow
  • Straightness of the blind hole has a linear response to the fill speed (Figure 19)
    • Slowest fill speed has least distortion
    • Fastest fill speed has the worst distortion

  • Difference in lower bainite was the cause for differences in distortion with respect to oil stagnancy around the structural beam previously shown.
  • Differences in distortion from the oil fill rate of the main tube are not caused by microstructural phase differences.
  • Figure 18 shows that Martensite and Lower Bainite are the same for all fill speeds.
  • Differences in distortion are caused by the transformation timing along the axis of the landing gear.

 

 

 

 

 

Immersion Direction Sensitivity

Figure 19

  • Distortion sensitivity to the immersion direction was examined.
  • Figure 19 compares temperature profile at the end of the immersion process for the two immersion directions.
  • The Baseline has oil enter the blind hole first and then fill up the tube at a rate that is 20% of the immersion speed.
    • Oil spills over the top of the tube and the tube is flooded with oil.
  • The reversed immersion has oil enter the tube first and fills at the immersion speed.

  • Figure 20

    Reversing the immersion direction also reverses the axial temperature gradient.

    • Martensite transformation starts at the open tube end when the immersion direction is reversed.
    • Martensite transformation starts by the blind hole first for the Baseline.
    • Reversing the axial phase transformation gradient can have significant effects on bow distortion and axial displacement.
  • Figure 20 shows the vertical displacement around the blind hole for the Baseline and the Reversed Immersion.
  • Reversing the immersion direction had a very minor impact on the straightness of the blind hole.
    • Closed side of blind hole was pulled further down by reversing the immersion direction, but the closed side

      Figure 21

      was not pulled up as much.

  • Figure 21 shows the bow distortion in the XY-Plane for the Baseline and the Reversed Immersion.
  • Reversing the immersion direction has a significant effect on the bow distortion in the XY-Plane, nearly doubling it.
  • Reversing the immersion direction has no effect on the bow distortion in the YZ-Plane.

 

 

 

Conclusions

  • Four process parameters were evaluated for distortion sensitivities for a large landing gear component:
    • Oil stagnancy inside a blind hole, oil stagnancy around a structural support beam, oil fill rate into the main tube as the landing gear is lowered into the oil tank, and immersion direction of the landing gear.
  • Three distortion modes were evaluated:
    • Bow distortion in XY-Plane, bow distortion in YZ-Plane, and straightness of a blind hole.
  • Bow distortion in the XY-Plane IS significantly affected by oil stagnancy around structural support beam, oil fill rate up the main tube, and the immersion direction.
    • Bow distortion in the XY-Plane is mainly controlled by the behavior of the structural support beam.
  • Bow distortion in the XY-Plane IS NOT significantly affected by oil stagnancy in the blind hole.
  • Bow distortion in the YZ-Plane IS significantly affected by oil fill rate of the main tube.
    • Bow distortion in the YZ-Plane is mainly controlled by a fitting near the open end of the tube that contributes to non-symmetric mass around the main tube in that area.
  • Bow distortion in the YZ-Plane IS NOT significantly affected by oil stagnancy in the blind hole, oil stagnancy around the structural support beam, or the immersion direction.
  • Straightness of the blind hole IS significantly affected by oil stagnancy around structural support beam and the oil fill rate up the main tube .
    • Straightness of the blind hole is mainly controlled by the structural support beam behavior.
  • Straightness of the blind hole IS NOT significantly affected by oil stagnancy inside the blind hole or the immersion direction.
  • Modifications to the quenching process were made to improve the distortion response of the landing gear.
    • Modeling results were used to direct the modifications.
    • Customer considered changes proprietary and did not share.
  • Benefit of using heat treatment simulation over physical experiments to perform sensitivity studies was shown.
    • Ability to modify, and see the effects of, just one process parameter with simulation is easy.
    • Ability to modify, and see the effects of, just one process parameter with experiments is very difficult, if not impossible.
    • Cost of simulation is minimal.
    • Cost of physical experiments can be very high.

 

Text developed from powerpoint version. Click here to view or for more information on DANTE case studies.

 

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Heat Treat Tips: Quenching

/ FEATURED NEWS, MANUFACTURING HEAT TREAT, MANUFACTURING HEAT TREAT NEWS, QUENCHING TECHNICAL CONTENT

During the day-to-day operation of heat treat departments, many habits are formed and procedures followed that sometimes are done simply because that’s the way they’ve always been done. One of the great benefits of having a community of heat treaters is to challenge those habits and look at new ways of doing things. Heat Treat Today‘s 101 Heat Treat Tips, tips and tricks that come from some of the industry’s foremost experts, were initially published in the FNA 2018 Special Print Edition, as a way to make the benefits of that community available to as many people as possible. This special edition is available in a digital format here.

In today’s Technical Tuesday, we continue an intermittent series of posts drawn from the 101 tips. The category for this post is Quenching, and today’s tips–#8, #38, and #81–are from three different sources: Dan Herring,  “The Heat Treat Doctor®”, of The Herring Group; Combustion Innovations; and Super Systems, Inc. 

Heat Treat Tip #8

14 Quench Oil Selection Tips

Dan Herring,  “The Heat Treat Doctor®”, of The Herring Group

Here are a few of the important factors to consider when selecting a quench oil. 

  1. Part Material – chemistry & hardenability 
  2. Part loading – fixturing, girds, baskets, part spacing, etc. 
  3. Part geometry and mass – thin parts, thick parts, large changes in section size 
  4. Distortion characteristics of the part (as a function of loading) 
  5. Stress state from prior (manufacturing) operations 
  6. Oil type – characteristics, cooling curve data 
  7. Oil speed – fast, medium, slow, or marquench  
  8. Oil temperature and maximum rate of rise 
  9. Agitation – agitators (fixed or variable speed) or pumps 
  10. Effective quench tank volume 
  11. Quench tank design factors, including number of agitators or pumps, location of agitators, size of agitators, propellor size (diameter, clearance in draft tube), internal tank baffling (draft tubes, directional flow vanes, etc.), flow direction, quench elevator design (flow restrictions), volume of oil, type of agitator (fixed v. 2 speed v. variable speed), maximum (design) temperature rise, and heat exchanger type, size, heat removal rate in BTU/hr & instantaneous BTU/minute.
  12. Height of oil over the load 
  13. Required flow velocity through the workload 
  14. Post heat treat operations (if any) 

Submitted by Dan Herring,  “The Heat Treat Doctor®”, of The Herring Group.

Heat Treat Tip #38

Oil and Water Don’t Mix

Keep water out of your oil quench. A few pounds of water at the bottom of an IQ quench tank can cause a major fire. Be hyper-vigilant that no one attempts to recycle fluids that collect on the charge car.

Submitted by Combustion Innovations

Heat Treat Tip #81

Quench Oil Troubles

According to Super Systems, Inc., there are one of three problems to consider if your quench is just not cutting it. Although SSI focuses more on atmosphere control systems, when parts come out soft, the problem isn’t always the atmosphere – sometimes it’s the quench. Here are three things to consider regarding your quench:

  • First, check the composition of the quench media. Is it up to spec? Does it need to be refreshed?
  • Is the quench receiving adequate agitation to thoroughly quench the load?
  • Is the quench at the right temperature? If the bath is too warm when the load enters, quenching won’t go well!

Submitted by Super Systems, Inc.

 

Photo credit: Heat Treat Today FNA 2018; Super Systems, Inc.

If you have any questions, feel free to contact the expert who submitted the Tip or contact Heat Treat Today directly. If you have a heat treat tip that you’d like to share, please send to the editor, and we’ll put it in the queue for our next Heat Treat Tips issue. 

Heat Treat Tips: Quenching Read More »

Heat Treating Race Car Parts with Quick Turnaround for Race Event

/ AUTOMOTIVE HEAT TREAT, AUTOMOTIVE HEAT TREAT NEWS, FEATURED NEWS, TEMPERING

BOTW-50w  Source:  MetLabHeattreat.com

Metlab has worked with a number of NASCAR and Indy Racing Car Teams and also companies that restore antique cars, sports and muscle cars and has a history of heat treating race car parts that must endure severe conditions. Big B Manufacturing is a specialty machine shop located in Klingerstown, PA which specializes in design and engineering as well as machining of small and large components. They also make and race off road cars. Big B brought a project to Metlab that required the heat treating of four (4) link arms.  The arms are fabricated from 4130 steel and TIG welded with 4130 filler. The suspension parts are for Big B Manufacturing’s racing team.

Read More:  Heat Treating Race Car Parts with Quick Turnaround for Race Event by Metlab Heat Treat

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TMK-ARTROM Orders Austenitizing Tube Heat-Treatment Line

/ ENERGY HEAT TREAT, FEATURED NEWS

SMS group received an order from Romania’s TMK-ARTROM for a heat-treatment line for tubes. The line will consist of an austenitizing furnace with walking-beam transport system, quenching head, quenching tank, walking-beam tempering furnace and cooling bed. It will allow various process steps, such as quenching, tempering and normalizing. The line, which will be able to treat tubes up to a wall thickness of 60 mm (2.4 inches), is scheduled to start up in the second quarter of 2017.

TMK-ARTROM’s plant in Slatina produces seamless tubes, OCTG pipes and high-strength tubes for mechanical applications. It has an annual capacity of 160,000 tons. This heat-treatment line, which also includes eco-friendly recuperative burners in the furnaces, will strengthen TMK-ARTROM’s presence in the market for tubes for oil and gas exploration

 

TMK-ARTROM Orders Austenitizing Tube Heat-Treatment Line Read More »

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