In today’s Technical Tuesday installment, we highlight the various techniques and developments in the world of metal AM as it pertains to post-process heat treating. Check out the trivia quiz below to test your knowledge of the AM/3D industry, the processes, and the technology.
This feature was first released inHeat Treat Today’sJanuary 2025 Technologies To Watch in Heat Treating print edition.
Additive manufacturing (AM), commonly known as 3D printing, has a history marked by constant innovation for uses across the space, aerospace, medical, food, and manufacturing industries, to name a few. While AM is known to support, streamline, and customize part production, advanced materials paired with evolving AM techniques are creating new possibilities in materials engineering and industrial manufacturing. Due to the nature of this ever-developing technology, in-house heat treaters must continually learn about AM components and how thermal processing may enhance component properties.
Emanuel “Ely” Sachs
What was the original name for additive manufacturing (AM), circa 1980s? A) 3D printing B) Rapid prototyping (RP) C) Additive manufacturing (AM) D) Rapid tooling (RT)
What grade of stainless steel is most commonly used for AM to achieve varying levels of strength, hardness, and elongation when heat treated? A) 17-4 PH B) 316L C) 304 D) 430
Who is Emanuel “Ely” M. Sachs? A) An engineer at GE Aviation who combined multiple parts into one huge, complex design using a laser-based additive manufacturing method called direct metal laser melting B) An engineer at Stratasys Ltd., an American-Israeli manufacturer that began using a material extrusion based process with their FFF (fused filament fabrication) technology to print parts, patented in 1989 C) A professor of Mechanical and Materials Engineering at Worchester Polytechnic Institute who evaluated the post process heat treating of DMLS titanium alloy parts D) An MIT engineering professor who patented the process of metal binder jetting technique in 1993
What do cast parts made from powder metallurgy methods and AM parts have in common? A) The same heat treatment cycles produce the best results B) Custom cycles are used in less than 2% of both applications C) Parts exhibit porosity D) None of the above
What are the most commonly adjusted parameters to achieve higher yield strength when heat treating AM parts? A) Cooling and heating rate B) Temperature and time C) Time and pressure D) Temperature and pressure
Why is HIP known as the “gold standard” for processing AM parts for space? A) Eliminates porous microstructures without compromising the part’s geometries and dimensions B) High level of control and uniformity C) Combines high temperature and pressure to improve a part’s mechanical properties D) All of the above
What is NOT a potential benefit of additive manufacturing? A) Immediate cost savings B) Fast part production C) Rapid prototyping D) Opportunity for increased automation and use of robotics
What are the two main categories for most 3D printing methods? A) Those that use liquid binding polymers, and those that don’t B) Binder jetting technology (a non-melt-based process) and melt-based processes C) Both A and B D) Neither A nor B
Which alloy was originally developed for aerospace applications but became one of the most common biomedical alloys? A) Inconel 718 B) Inconel 625 C) Ti-6Al-4V D) Hastelloy C22
What was the first rapid prototyping method to produce metal parts in a single process (and is one of the most widely used AM technologies to manufacture Ti-6Al-4V parts)? A) Powder-bed fusion (PBF) B) Directed energy deposition (DED) C) Sheet lamination (SL) D) Direct metal laser sintering (DMLS)
In what way does high temperature processing — specifically HIP below the annealing temperature (1470°F/799°C) — improve DMLS Ti-6Al-4V parts? A) Preserves surface roughness and enhances osteointegration B) Reduces porosity and enhances corrosion resistance C) Both A and B D) Neither A nor B
What is the ideal way to process 3D printed parts made using liquid binder polymers? A) Print the parts in-house followed by debind and sinter. B) Have AM parts delivered in-house for heat treating when parts are at the “Green” stage C) Have AM parts delivered in-house for heat treating when parts are at the “Brown” stage D) None of the above
Laser heat treating overcomes issues of distortion that are frequent in conventional heat treating methods. Read this Technical Tuesday by Aravind Jonnalagadda (AJ), CTO and co-founder of Synergy Additive Manufacturing LLC, who examines how the automotive industry is achieving desirable dimensional tolerance while avoiding finishing operations like hard milling or grinding.
This informative piece was first released in Heat Treat Today’s August 2024 Automotive print edition.
Technology Overview
Laser heat treatment is a process in which a laser, with a typical spot size from 0.5” x 0.5” to 2” x 2”, illuminates the surface of a metal part to deliver very high energy flux with extreme precision both in time and geometry. This brings the metal’s surface up to the desired temperature very rapidly. Movement of the laser across the surface of the working piece produces hardened tracks.
The phase transformations induced by laser hardening of steels proceed according to the following stages:
Formation of austenite from pearlite-cementite (hypereutectoid steels) or from pearlite-ferrite (hypoeutectoid steels) aggregate structure, during the heating stage.
Martensite transformation from austenite, during the cooling stage.
During this process the short interaction time, in the range of 0.1–0.2 seconds, brings the surface temperature to 1337°F –2732°F (725°C –1500°C). Under these conditions, the original pearlite colonies transform into high-carbon metastable martensite due to self-quenching. This martensite phase increases the hardness.
Key Benefits of Laser Heat Treating
Consistent Hardness Depth: Laser heat treatment delivers consistent hardness and depth by precisely applying high energy to the metal. Millisecond-speed feedback control of temperature ensures specifications are met, as shown in the metallographic cross-section view of laser heat treated D6510 cast iron (Figure 3).
Minimal to Zero Distortion: The high energy density of laser heat treatment minimizes distortion, benefiting components like large automotive dies, gears, bearings, and shafts.
Precise Application of Beam Energy: The laser spot precisely heats the intended area, avoiding unnecessary heating of surrounding areas. This is particularly advantageous for surface wear applications, allowing for surface hardening while maintaining the rest of the material in a medium-hard or soft state, thus combining hardness and ductility.
No Hard Milling or Grinding Required: Laser heat treatment’s low-to-zero distortion reduces or eliminates the need for hard milling or grinding. Post-treatment material removal is minimal and can be managed with polishing. This reduction in finishing operations can save up to 20% in overall manufacturing costs.
Laser Heat Treatable Materials
Any steel with ≥ 0.2% carbon content is treatable by laser heat treatment. In real-world applications, the areas of dies that have been treated with laser heat treatment are generally as hard as, or harder than, the same areas of identical dies treated by conventional hardening treatment.
Common heat treatable automotive materials are indicated in Table 1. This is not a comprehensive list.
In automotive tooling, the conventional practice is to mill the dies in soft state, intentionally leaving an extra 0.015” to 0.020” of material on the surfaces. This excess material acts as a buffer to accommodate distortions from subsequent heat treatments like flame or induction processes. After this initial phase, the dies undergo heat treatment and are then hard milled to achieve the specified tolerances before assembly.
Figure 1. Conventional die construction process vs. the process that utilizes laser heat treating
An alternative method gaining traction, however, is laser heat treating (Figure 1). In this approach, the dies are machined to final tolerance from the beginning and then laser heat treated without causing distortions. This eliminates the need for a secondary hard milling operation. Automotive tool and die clients have reported cost savings exceeding 20% due to this streamlined process.
New Advancements
A Promising Application: Hardening Sharp Edges on Trim Dies
Figure 2. Trim die being laser heat treated using Synergy’s Multi-Point Temperature Control System
Within the automotive industry, trim dies hold a pivotal role in shaping sheet metal stampings (Figure 2). These dies are instrumental in cutting the metal sheets after forming operations. Typically, a trim die comprises numerous smaller steels assembled onto a die shoe. Ensuring the durability and hardness of these trim dies is imperative, as they must withstand considerable shear and fatigue loads.
Traditionally, heat treatment methods like flame or induction have been employed for treating trim inserts. However, these conventional techniques come with inherent drawbacks. Issues such as rolled edges and high heat input often lead to significant distortion in the dies. To compensate for this distortion, die makers commonly leave approximately 0.020” of stock material, which then requires hard milling to meet specifications. This process consumes substantial time and resources.
To address these challenges effectively, many die makers have recently turned towards laser heat treating for their trim inserts.
Multi-Point Temperature Control System (MPTC)
Figure 3. Cross-section of test sample demonstrating laser heat treated trim edge and the hardness of the cutting edge
Another innovation has been the use of more advanced temperature control units. The need to overcome temperature control challenges led to the development of the Multi-Point Temperature Control System (MPTC). This system enables Synergy to regulate laser power and temperature distribution over the entire cutting edge, ensuring consistent and controlled heat treatment without melting the cutting edge.
Case Study: Press Brake Tooling Hardening
High precision press brake tools are essential for the metalworking industry, providing the necessary precision and durability for bending and shaping sheet metal. These tools are crafted from a variety of materials, including 4140, S7, A2, and D2 steels, each known for their unique properties and performance characteristics. However, hardening these tools presents significant challenges due to their lack of mass, which often leads to serious distortion, especially in longer pieces.
Traditional hardening methods can cause substantial distortion in press brake tooling. This is particularly problematic for long tools, where uneven heating and cooling can lead to warping. The need for precise dimensions and smooth operation in press brake tooling makes any level of distortion unacceptable, as it can affect the accuracy and quality of the final product.
Laser hardening of press brake tooling at Synergy has demonstrated remarkable results. For tools less than 10 inches in length, the recorded distortion is less than 0.001 inches. Even for longer tools, measuring up to 10 feet, the overall distortion was maintained at less than 0.050 inches.
Case Study: Hem Die Laser Heat Treatment
Hemming is a critical operation in the production process and has a significant impact on the overall quality and performance of a vehicle. Hemming involves bending the edge of a sheet metal over itself, and it is performed on various components such as hoods, doors, tailgates, and fenders. Hemming dies, also known as anvils, play a crucial role in this process and are compact compared to conventional stamping dies, but this presents a new set of challenges for die makers.
Figure 5. Hem die laser hardening on the perimeter edge (material D6510 cast iron, typical hardness 58-62 HRC)
Conventional heat treating methods, such as induction and flame hardening, can cause substantial distortion in hemming dies and result in inconsistent hardness across the profile. Additionally, the dies require a great deal of post-machining to bring them back to the desired tolerance. This not only results in substantial cost but also adds time to the production process, leading to increased time to market (TTM).
Laser heat treating offers a solution to these challenges and helps to maintain the quality of hemming dies. With Synergy’s laser heat treating process, the die is laser heat treated after it is machined to its final dimensions, resulting in minimal to no distortion and consistent hardness. This eliminates the need for additional hard milling processes and helps to reduce the TTM. Extensive testing by Synergy’s clients has shown that laser heat treated anvils exhibit consistent hardness within ±1 HRC and do not require additional hard milling operations.
Uniform laser heat treating of punch pins with distortion of less than 0.0005” can be achieved with laser heat treating on pins and other cylindrical components. A demonstration of this application on a 4140 alloy steel part is depicted in the Figure 6. Laser hardening resulted in a surface hardness of 60 HRC with a case depth of 0.010”.
The automotive industry increasingly requires precise, repeatable methods to not only meet standards but also remove steps for manufacturers creating these components. As the three case studies demonstrate, laser heat treating is a key tool that heat treaters should use to improve energy efficiency, avoid distortion, and increase overall quality.
Asnafi, Nader, Tuve Johansson, Marc Miralles, and Andreas Ullman. “Laser Surface-Hardening of Dies for Cutting, Blanking or Trimming of Uncoated DP600.” Recent Advances in Manufacture & Use of Tools & Dies and Stamping of Steel Sheets, Olofström, Sweden (October 5-6, 2004).
Beyer, E., F. Dausinger, A. Ostendorf, A. Otto. “State of the Art of Laser Hardening and Cladding.” Proceedings of the third International WLT-conference on Lasers in Manufacturing, (2005): 281–305.
Pashby, I.R., S. Barnes, and B. G. Bryden. “Surface hardening of steel using a high power diode laser.” Journal of Materials Processing Technology, University of Nottingham, Nottingham, UK b Warwick Manufacturing Group, University of Warwick, Warwick, UK,139, (2003): 585–588.
Selvan, J. Senthil, K. Subramanian, and A. K. Nath. “Effect of laser surface hardening on En18 (AISI 5135) steel.” Journal of Materials Processing Technology 91, 1–3 (June 1999): 29–36.
Aravind Jonnalagadda (AJ) has over 20 years of expertise in laser material processing. Synergy provides high power laser-based solutions for complex manufacturing challenges related to wear, corrosion, and tool life specializing in laser systems and job shop services for laser heat treating, metal based additive manufacturing, and laser welding.
IperionX, a U.S. titanium metal and critical materials company, recently delivered its first successful titanium furnace production run at the company’s Titanium Manufacturing Campus, based in Virginia. The furnace was installed in April 2024 with full run rate target capacity of at least 125 metric tons per year anticipated by the end of the year.
Anastasios (Taso) Arima CEO IperionX Source: IperionX
IperionX announced the commissioning of the Hydrogen Assisted Metallothermic Reduction (HAMRTM) furnace, noting that the titanium de-oxygenation production run represents a technological milestone for the company with a breakthrough +60x increase in titanium production capacity. The company’s titanium metal and critical minerals are processed for the consumer electronics, space, aerospace, defense, hydrogen, electric vehicles, and additive manufacturing industries.
“Over the last two years, we have successfully operated our pilot titanium production facility in Utah, producing high performance titanium products for customers and importantly – delivering first revenues for our company,” said Anastasios (Taso) Arima, CEO of IperionX.“Today, we demonstrated that our HAMR technology works at commercial scale. We successfully increased the furnace production capacity by ~60x times and produced high performance titanium that exceeds industry quality standards.”
The HAMR furnace is produced entirely from 100% scrap titanium (Ti-6Al-4V alloy, Grade 5 titanium), with a confirmed reduction in oxygen levels from 3.42% to below 0.07%, far exceeding the ASTM standard requirement of 0.2% for Grade 5 titanium. IperionX’s proprietary HAMR technologies offer a range of competitive advantages, including lower operating temperatures, reduced energy consumption, enhanced process efficiency, and accelerated production cycles.
The press release is available in its original form here.
IperionX, a producer of high-quality titanium alloys, has commissioned a titanium production facility in Virginia.
Anastasios (Taso) Arima, CEO of IperionX, commented in a letter to the company’s shareholders: “Our Virginia titanium facility is designed to apply our HAMR [Hydrogen Assisted Metallothermic Reduction] and HSPT [Hydrogen Sintering & Phase Transformation] technologies to produce sustainable, high-quality and high strength titanium metal products at low cost.”
Full capacity is scheduled for 2026, with more than 1,000 metric tons of titanium produced per year. Using titanium powder produced on site, IperionX plans to employ unique forging technologies to produce titanium mill products and near net shape titanium products and to apply AM to produce 3D printed titanium products.
Arima also added, “We engaged with Lockheed Martin, GKN Aerospace, and the U.S. Army to replace traditional titanium mill products, in this case titanium plate, providing a new domestic and sustainable source to enhance their critical supply chains.” To aid these goals, Iperion is installing a large-scale, industrial furnace at their Virginia facility.
This letter to IperionX’s shareholders can be found here.
Metal 3D additive manufacturing has grown dramatically in the last five years. Nearly every metal printed part needs to be heat treated, but this presents some challenges. This article will address some of the challenges that a heat treater faces when working with these parts.
This Technical Tuesday article, written by Mark DeBruin, metallurgical engineer and CTO of Skuld LLC, was originally published in December 2023’sMedical and Energy magazine.
Mark DeBruin Metallurgical Engineer and CTO Skuld LLC
In my experience, on average, about 10% of all 3D metal printed parts break during heat treatment; this number varies depending on the printer and the unique facility. While materials can be printed with wire or even metal foils, I’m going to mainly focus on the approximately 85% of all metal 3D printed parts that are made from metal powder and either welded or sintered together.
Most metal printed parts normally have heat added to them after printing. In addition to the heat of the printing process and wire electrical discharge machining (EDM) process to separate the part from the build plate, heat may be added up to five times. These steps are:
Burnout and sintering (for some processes such as binder jet and bound powder extrusion)
Stress relieving
Hot isostatic pressing (HIP)
Austenitizing (and quenching)
Tempering
3D printing can create a non-uniform microstructure, but it will also give properties the client does not normally desire. Heat treating makes the microstructure more uniform and can improve the properties. Please note that heat treating 3D printed parts will never cause the microstructure to match a heat treated wrought or cast microstructure. The microstructure after heat treating depends on the starting point, which is fundamentally different.
If the part is not properly sintered, there is a high chance it will break during heat treatment. It may also exhaust gases, which can damage the heat treat furnace. The off gases will recondense on the furnace walls causing the furnace to malfunction and to need repair. This can potentially cost hundreds of thousands of dollars.
During powder 3D printing, there is a wide variety of defects that can occur. These include oxide inclusions, voids, unbonded powder, or even cracks that occur due to the high stresses during printing. Even if there are not actual defects, the printing process tends to leave a highly stressed structure. All of these factors contribute to causing a print to break as the inconsistent material may have erratic properties.
In a vacuum furnace, voids can be internal and have entrapped gas. Under a vacuum, these can break. Even if something was HIP processed, the pores can open up and break. Even if they do not break and heat is applied, the metal will heat at different rates due to the entrapped gas.
Figure 1. Macroscopic view of a 3D printed surface (left) compared to machined surface (right) (Source: Skuld LLC)
There are also issues during quenching due to the differences in the surface finish. In machining, the surface is removed so there are not stress concentrators. In 3D printing, there are sharp, internal crevices that can be inherent to the process that act as natural stress risers (see Figure 1). These can also cause cracking.
When 3D printed parts break, they may just crack. This can result in oil leaking into the parts, leading to problems in subsequent steps.
Figure 2. Example wire mesh basket (Source: Skuld LLC)
However, some parts will violently shatter. This can happen when pulling a vacuum, during ramping, or during quenching. This can also cause massive damage to the furnace or heating elements. It can potentially also injure heat treat operators.
A lot of heat treaters protect their equipment by putting the parts into a wire mesh backet (Figure 2). This protects the equipment if a piece breaks apart in the furnace, and if a piece breaks in the oil, it can be found.
Print defects in metal 3D printed parts can be a challenge to a heat treater. Clients often place blame on the heat treater when parts are damaged, even though cracking or shattering is due to problems already present in the materials as they had arrived at the heat treater. As a final piece of advice, heat treaters should use contract terms that limit their risks in these situations as well as to proactively protect their equipment and personnel.
About The Author
Mark DeBruin is a metallurgical engineer currently working as the chief technical officer at Skuld LLC. Mark has started five foundries and has worked at numerous heat treat locations in multiple countries, including being the prior CTO of Thermal Process Holdings, plant manager at Delta H Technologies, and general manager at SST Foundry Vietnam.
The appeal of additive manufacturing (AM) for producing orthopedic implants lies in the “ability to design and manufacture complex and customized structures for surgical patients in a short amount of time.” To complement speed of production, learn how an innovative hot isostatic pressing (HIP) application is confronting the challenges of post-processing heat treatments when creating high quality AM medical parts.
Today’s Technical Tuesday article, written by Andrew Cassese, applications engineer; Anders Magnusson, manager of Business Development; and Chad Beamer, senior applications engineer, all from Quintus Technologies, was originally published in Heat Treat Today’sDecember 2023’s Medical and Energy Heat Treat magazine.
AM is playing a significant role in the medical industry. It gives manufacturers the ability to create customized and complex structures for surgical implants and medical devices. Additionally, medical device manufacturers have different material factors to consider – such as biocompatibility, corrosion resistance, strength, and fatigue – when selecting a material for a given application. Each of these factors plays a significant role. It’s no wonder that the most common metallic biomaterials in today’s industry are stainless steels, cobalt-chrome alloys, and titanium alloys (Trevisan et al., 2018).
In this article, learn about the application of Ti6Al4V in the medical industry, as well as ways to address some of the challenges when producing AM medical components.
The Future Demands Orthopedic Implants
Figure 1. Example of AM trabecular structure on a Ti6Al4V
acetabular cup (Source: Quintus Technologies)
The medical market for orthopedic implants is predicted to grow annually by approximately 4% where joint replacement, spine, and trauma sectors are reported to account for more than two-thirds of the market. The largest portion is joint replacement with over a third of global turnover, reaching in excess of 20 million U.S. dollars in 2022 (ORTHOWORLD® Inc., 2023). This confirms an earlier study by Allied Market Research where spine, knee, and hip implants made up over 66% of the entire market, with knee implants leading the way at 26% (Allied Market Research Study, 2022). This fact, combined with the expectation that the global population aged 60+ is predicted to double between 2020 and 2050, adds to the increasing demand on manufacturers to produce better quality and longer lasting orthopedic implants (Koju et al., 2022).
These factors have increased the predicted medical implant market for Ti6Al4V and other common orthopedic materials. Using AM processes such as electron beam melting (EBM) and laser powder beam fusion (L-PBF), manufacturers can produce thin-walled trabecular structures that are fabricated to promote bone ingrowth in a growing market that is in competition with traditional production methods.
Titanium-based alloys have been increasingly used in orthopedic applications due to their high corrosion resistance and a Young’s modulus similar to that of human cortical bone (Kelly et al., 2021). The high strength-to-weight ratio and bioinert-ness of Ti6Al4V has proven it to be an ideal candidate for orthopedic and dental implants. It is a titanium alloy with 6% aluminum and 4% vanadium that has low density, high weldability, and is heat treatable. Ti6Al4V demonstrates good osteointegration properties, which is defined as the structural and functional connection between living bone and the surface of a load carrying medical implant.
Many manufacturers are using L-PBF to create thin-walled complex structures on the surface of the implant. This makes use of the osteointegration properties as the implant integrates itself into the body over time without the need for bone cement (Kelly et al., 2021). Introducing a large metallic foreign body leads to challenges such as promotion of chronic inflammation, infection, and biofilm formation. Instead, porous AM Ti6Al4V implants have a biomimetic design attempt towards natural bone morphology (Koju et al., 2022).
AM Yields Production Solutions for Medical Alloys
The medical industry has been increasing the use of AM over traditional processing methods. AM facilitates weight reduction, material savings, and shortened lead-time due to reduced machining, but these are only a few of the benefits. Improved functionality and patient satisfaction are also key aspects through tailoring of designs to take advantage of AM over traditional forging and casting techniques. Additionally, the costs of machining a strong alloy like Ti6Al4V can be expensive, and any wasted material and time in turn lead to higher cost.
One of the main reasons for the interest in AM is the ability to design and manufacture complex and customized structures for surgical patients in a short amount of time. For example, if a patient needs an implant for surgery, an MRI scan can help reverse engineer a customized implant. Engineers prepare a design of a patient-specific implant according to the patient’s anatomy that is then printed, HIPed, and finished for surgery with a reduced lead time. This is especially important for trauma victims, where the speed of repair can mean the difference between losing a limb or returning to a fully functional life. Cancer victims and those requiring aesthetic surgery to the skull, nose, jaw, etc., can also benefit from this (Benady et al., 2023).
Some of the current challenges with AM titanium in the medical industry are related to the post-processing heat treatments that are required. These treatments can leave an oxide layer on thin-walled structures that is hard to remove by machining or chemical milling. Quintus Purus®, a unique clean-HIP solution, has proven to overcome this challenge and provide clients with a robust solution that both densifies and maintains a clean surface.
When HIP Meets AM
Figure 2. AM Ti6Al4V components HIPed without getter using conventional HIP (left) and Quintus Purus® (right) (Source: Zeda)
HIP is important in the AM world as a post-process that closes porosity and increases fatigue life. For medical implants, high and low cycle fatigue life properties are key as they affect the longevity of the repair. The mechanical strength and integrity are improved significantly by HIPing the implants, reducing the need for further surgery on the same patient. Modern HIP cycles have been developed to further increase this performance. When combined with Quintus Purus®, modern HIP cycles can minimize the thin, oxygen-affected layer that can result from thermal processing on surfaces of high oxygen-affinitive materials, such as titanium.
For Ti6Al4V, this layer is often referred to as alpha-case. The brittle nature of the alpha-case negatively impacts material properties resulting in medical manufacturers requesting their AM parts in the “alpha-case free” state. Alpha-case can be formed during heat treatment. As surfaces of the payload and process equipment are exposed to oxygen at elevated temperatures, they may be oxidized or reduced, depending on the oxide to oxygen partial pressure equilibrium. During heat treatment, evaporating compounds become part of the process atmosphere, and solids are deposited or formed on other surfaces, either as particles or as surface oxides.
For titanium alloys, surface oxides are formed at logarithmic or linear rates, depending on temperature and oxygen partial pressure. At the same time, oxygen can diffuse into the surface to form the brittle alpha-case, which is detrimental to the part’s fatigue performance. Changes of the surface color can often be seen as an indication that surface reactions have occurred during processing when using traditional thermal processes (Magnusson et al., 2023).
The HIP furnace atmosphere contaminants that cause this oxidation can originate from various sources including the process gas, equipment, furnace interior, and, most importantly, the parts to be processed. The payload itself often absorbs moisture from the surrounding atmosphere before being loaded into the furnace, which is subsequently released into the HIP atmosphere during processing. Industrial practice today attempts to solve the issue by wrapping parts in a material such as stainless steel foil or a “getter” that has a high affinity to oxygen protecting the Ti6Al4V component from exposure to large volumes of process gas, thus helping minimize the pickup of the contaminates.
This method adds material, time, and labor to wrap and unwrap parts before and after each HIP cycle. Also, wrapping in getter cannot guarantee cleanliness and may result in some uneven oxidation. This is where the tools of Quintus Purus® are of assistance; these tools allow the user to define a maximum water vapor content that can be accepted in the HIP system before the process starts. The tool utilizes the Quintus HIP hardware together with a newly developed software routine, ensuring that the target water vapor level is met in the shortest time possible. The result is a cleaner payload, without the need to directly wrap components with getter (Magnusson et al., 2023).
Table 2. Results from case study productivity analysis
(Source: Quintus Technologies)Table 1. Input to case study (Source: Quintus Technologies)
Alpha-Case Avoided: Comparing Conventional HIP and Optimized HIP Technologies
Quintus Technologies performed a study with Zeda, Inc. to evaluate Quintus Purus® on L-PBF Ti6Al4V medical implant parts. The study was performed in the Application Center in Västerås, Sweden in a QIH 21 HIP. A conventional HIP cycle was performed as well as an optimized Quintus Purus® HIP cycle, both without the use of getter. No presence of alpha-case was found on the part processed with the Quintus Purus® cycle as shown in Figure 2 below (Magnusson et al., 2023).
Quintus Purus® can be further enhanced with the use of a Quintus custom-made getter cassette supplied as part of the installation, which consumes or competes for the remainder of contaminant gaseous compounds still present in the system after all other measures such as best practice handling, adjustment of gas quality, etc., have been implemented.
Titanium is considered the getter of choice for Quintus Purus® and is included as an optional compact getter cassette placed at the optimum position in the hot zone of the HIP furnace. Although the custom-made getter cassette occupies a small space, its use can significantly increase loading efficiency. The traditional way of individually wrapping components with stainless steel or titanium foil will consume more furnace volume, through reduced packing efficiency, leading to less components per cycle when compared to the Quintus Purus® titanium getter cassette strategy. Using an average spinal implant size of 2 in3 (32 cm3), one can calculate the packing density in a standard HIP vessel assuming two shifts per day and a 90% machine uptime. For example, a Quintus Technologies QIH 60 URC with a hot zone diameter of 16 in (410 mm) and a height of 40 in (1,000 mm) can pack up to 1,280 implants per cycle, with clearances for proper spacing and load plates.
Figure 3. Quintus Technologies QIH 60 URC outfitted with
Quintus Purus® technology (Source: Quintus Technologies)
The typical Ti6Al4V HIP parameters include a soak time of two hours at 1688°F with 14.5 ksi argon pressure (920°C with 100 MPa). Accounting for heat up and cool down time, this HIP cycle can take less than eight hours, allowing two cycles per day on a two-shift work schedule. A typical case of wrapping each component in getter material adds time, cost, resources, and uses up to an estimated 50% of the load capacity. With the increased efficiency enabled by Quintus Purus®, clients have the opportunity to HIP 552,960 spinal implants per year (Tables 2 and Figure 3).
In conclusion, the growing Ti6Al4V market in the medical industry demands innovative developments to keep up with ever-increasing production volumes, whilst quality demands in lean production are becoming more significant. Solutions like the Quintus Purus® will allow manufacturers to have control over the quality of their titanium parts during a HIP cycle. It can be applied to produce alpha-case free components ensuring the optimal performance of orthopedic implants with increased service life.
References Ahlfors, Magnus, Chad Beamer. “Hot Isostatic Pressing for Orthopedic Implants.” (2020): https://quintustechnologies.com/knowledge-center/hiporthopedic-implants/. Allied Market Research Study performed for Quintus Technologies, 2022. Benady, Amit, Sam J. Meyer, Eran Golden, Solomon Dadia, Galit Katarivas Levy. “Patient-specific Ti-6Al-4V lattice implants for critical-sized load-bearing bone defects reconstruction.” Materials & Design 226 (Feb. 2023): https://www.sciencedirect.com/science/article/pii/S0264127523000205?via%3Dihub. Kelly, Cambre N., Tian Wang, James Crowley, Dan Wills, Matthew H. Pelletier, Edward R. Westrick, Samuel B. Adams, Ken Gall, William R. Walsh, “High-strength, porous additively manufactured implants with optimized mechanical osseointegration.” Biomaterials (Dec.2021): 279, https://www.sciencedirect.com/science/article/abs/pii/.
About the Authors
Andrew Cassese is an applications engineer at Quintus Technologies. He has a bachelor’s degree in welding engineering from The Ohio State University.
Anders Magnusson is the business development manager at Quintus Technologies with an MSc in engineering materials from Chalmers University of Technology.
Chad Beamer
Applications Engineer
Quintus Technologies
Chad Beamer is a senior applications engineer at Quintus Technologies, and one of Heat Treat Today’s 40 Under 40 Class of 2023 award winners. He has an MS from The Ohio State University in Materials Science and has worked as a material application engineer with GE Aviation for years and as a technical services manager with Bodycote. As an applications engineer, he manages the HIP Application Center located in Columbus, Ohio, educates on the advancements of HIP technologies, and is involved in collaborative development efforts both within academia and industry.
Sometimes our editors find items that are not exactly "heat treat" but do deal with interesting developments in one of our key markets: aerospace, automotive, medical, energy, or general manufacturing. To celebrate getting to the “fringe” of the weekend, Heat TreatToday presents today’s Heat Treat Fringe Fridaybest of the web article that investigate the success of 3D printing an engine part for John Deere.
In collaboration with GKN Sinter Metals, the project team was able to develop, qualify and introduce the Thermal Diverting Valve 3.0. – a stainless steel component in the fuel system. This is the company’s first 3D printed metal part in production. Using this production method, results are showing significant cost savings and less materials usage. R&D phase worked to develop a part that would outperform, in cold weather, the current valve. Testing in the lab and in the field have gone well; other projects could benefit including printing of replacement parts.
Thermal Diverter Valve 3.0 prototypes Source: John Deere UK IE/YouTube
An excerpt: "The new thermal diverter valve on the latest versions of John Deere 6R and 6M tractors isn’t just an innovative application of increasingly accessible metal 3D printing technology, it’s the culmination of about two years of R&D."
Additive manufacturing (AM) at a commercial scale began about 30 years ago and has expanded well beyond its original scope. As AM becomes increasingly prominent across different industries, heat treaters need to know how to handle AM parts in their shops. Learn about the history of binder jetting AM, the alloys used in this technology that require heat treatment, and what heat treaters should expect for the future.
Read why Animesh Bose of Desktop Metal thinks that binder jetting AM is only going to be used more and more in several heat treating sectors.
This article first appeared in Heat Treat Today’s December 2022 Annual Medical and Energy print edition.
Binder Jetting of Metals: Origins
Animesh Bose Vice President of Research & Development Desktop Metal Source: LinkedIn
Additive manufacturing (AM) at a commercial scale began about 30 years ago and has expanded well beyond its original scope. At the beginning, rapid prototyping (RP) was the name for the burgeoning technology; it emerged in the 1990s to bridge the gap between the need for quickly produced prototypes for manufacturers, not just plastic replicas. Rapid tooling (RT) of metal tooling parts joined RP R&D at this time as the research frontier for materials engineers. The current name for these technologies stands at “additive manufacturing,” or AM, though the popular terminology is simply “3D printing.”
Polymers
Developments in polymer AM also advanced rapidly with both extrusion-based technology as well as through advancements in Digital Light Processing of photopolymers. Stratasys Ltd., an American-Israeli manufacturer of 3D printers, software, and materials for polymer additive manufacturing as well as 3D-printed parts on-demand, began using a material extrusion-based process with their FFF (fused filament fabrication) technology to print parts, patented in 1989. This worked by feeding coils of polymeric materials though a printer, which would extrude the material through a small, heated chamber where the material would pass through a small orifice to extrude – or print – in a three dimensional design. This method allowed for very fine, hair-like material to print in a precise X ,Y, and Z motion, building layer by layer. Vat polymerization was another polymer AM technology that gained traction and involved photopolymer processing. Both technologies are currently used for polymeric materials. Interestingly, both processes have been adapted and are being used for metal 3D printing.
Metal AM
In 1993, an MIT engineering professor named Emanuel “Ely” M. Sachs – a man who could be considered the father of metal binder jetting technique – along with his colleagues from MIT patented the process of laying fluent, porous materials in layers between 50- to 100-micron thickness to form 3D parts. They were able to do this by spraying an organic binder on each layer of material where they wanted to increase the height of the part to produce a bonded layer in the selected area. This layering is repeated several times before the unbonded powder is removed immediately or after further processing.
One of the biggest advancements in metal AM happened in 2014 when GE Aviation combined multiple parts into one huge, complex design using a laser-based additive manufacturing method called direct metal laser melting. The end result was an airplane fuel nozzle made of 20 parts for the LEAP™ engine. All of AM came into the limelight, and direct metal laser melting – a melt-based technology – just took off.
But there were limitations to this laser process, the main one being cost and special powder requirements to layer and melt to form the part. The process was also technologically intensive and not fast enough for high volume production (as would be necessary for automotive or consumer good-type application).
Binder Jetting Technology
Binder jetting that had been developing in the early 2000s started to gain traction as a non-melt-based process for high volume mass production. Instead of melting the powder material, a binder is used to adhere the powder metal layers where needed. This method of printing results in a more uniform final part microstructure compared to the melt-based processes. ExOne, a binder jet 3D printing company, pursued the binder jetting technology using a license from MIT. In 2015, Desktop Metal was formed, and they focused on high volume mass production by binder jet using their Single Pass Jetting (SPJ™) technology. As binder jet gained traction, other companies entered the market (HP, GE, and Digital Metal). Desktop Metal recently acquired ExOne and efforts at developing standards for the technology are in full swing.
Heat Treating of AM Metals
Stainless Steels
There are two popular types of stainless steel for AM. The first is 17-4 PH, a precipitation-hardened stainless steel, which I like to call an “all purpose” stainless steel. When heat treated, one can achieve varying levels of strength, hardness, and elongation; and since it’s stainless steel it has a reasonable corrosion resistance. The aging treatments are already well-established – for example, H900, H1100, etc. The other popular grade is 316L, a non-heat treatable grade used in the food industry among others. Now, most stainless steels have chromium and nickel in decent amounts, so companies have developed a grade which is called “nickel-free stainless steel” for applications where people might be allergic to nickel. This class of alloy is also heat treatable. There are many more stainless steel grades that are being developed by the binder jet process.
Low Alloy Steels
Many low alloy steels are used in AM. For example, 4140 and 4340 have various, small amounts of alloying elements. These low alloy steels also need to be heat treated.
Tool Steels
Again, most tool steels are heat treatable. One of the most popular grades is H13; it is a tool steel that is heat treatable and can achieve fairly high hardness. It’s used for dies and other types of tooling.
Then, there is a category of tool steels known as A2 and D2; those are steels in which the strength can be changed through heat treatment.
Metal Alloys with Binder Jetting
There are also non-steel alloys that are used in binder jetting and require heat treatment. One example is nickel-based alloys, which fall in the broad category of super alloys. With some of these alloys, a heat treater would solutionize the part by taking it to a high temperature (950-1000°C), hold it for 60 minutes, and then quench in water, high pressure gas, or (in some instances) in air. The part then undergoes an aging treatment for several hours, depending on part thickness.
Additionally, there is a class of copper alloys with small amounts of zirconium and chromium that is heat treatable. These alloys have lower thermal and electrical conductivity compared to pure copper but have an advantage of higher strength and hardness over pure copper, which is very soft and malleable. For example, in applications that require additional strength and hardness compared to copper, the copper zirconium-chromium-based alloys may be appropriate since their strength and hardness can be increased by heat treatment.
This is just an introduction to the many alloys that have been used in binder jetting that need heat treatment.
Future of Binder Jet and Heat Treat
While heat treaters know about AM in the medical and aerospace industries, AM will likely gain more traction in the automotive industry. Presently, these are relatively small parts, but you will begin to see larger components coming from AM; one of the things to be aware of is that AM can create organic shapes, including all kinds of twisted and complex metal geometries. To ensure that these organic shapes do not distort or droop, larger parts must be well-supported. The development of a software known as Live Sinter™ by Desktop Metal offers the possibility of negatively distorting a complex shaped part (in the green state) so that after sintering, the part shrinks and distorts to eventually provide the desired complex shape at the end. This allows for the possibility of sintering parts either with minimal or without any support structures.
Heat treaters can also anticipate high volume AM production. This is one of the major focuses for binder jet engineers – to reduce costs for most automotive parts – as it will make AM very appealing to this cost-conscious industry.
Finally, optimizing sintering processes and related equipment for AM parts will result in meeting the production demands of the industry, and this will lead to AM parts being seen in heat treat shops more regularly. It would not be a stretch to consider (since there are heat treatments where gas atmosphere quenching at high pressures is possible), that the complete heat treatment cycle may be performed in the same furnace.
About the Author: Animesh Bose is the vice president of Research & Development at Desktop Metal, where he is responsible for building out the company’s palette of materials that can be used to print quality parts. He has been involved in the area of powder metallurgy and particulate materials (PM) for more than thirty years.
Sometimes our editors find items that are not exactly "heat treat" but do deal with interesting developments in one of our key markets: aerospace, automotive, medical, energy, or general manufacturing. To celebrate getting to the “fringe” of the weekend, Heat TreatToday presents today’s Heat Treat Fringe Friday press release: a look at the future of heat treating and 3D printing in aerospace engines and energy turbines.
Find out more about the possibilities of bringing additive manufacturing and heat treating turbine and engine components; and read on to see what's happening at MIT.
A new MIT-developed heat treatment transforms the microscopic structure of 3D-printed metals, making the materials stronger and more resilient in extreme thermal environments. The technique could make it possible to 3D print high-performance blades and vanes for power-generating gas turbines and jet engines, which would enable new designs with improved fuel consumption and energy efficiency.
There is growing interest in manufacturing turbine blades through 3D-printing, but efforts to 3D-print turbine blades have yet to clear a big hurdle: creep. While researchers have explored printing turbine blades, they have found that the printing process produces fine grains on the order of tens to hundreds of microns in size — a microstructure that is especially vulnerable to creep.
Zachary Cordero
Boeing Career Development Professor in Aeronautics and Astronautics
MIT
Zachary Cordero and his colleagues found a way to improve the structure of 3D-printed alloys by adding an additional heat-treating step, which transforms the as-printed material’s fine grains into much larger “columnar” grains. The team’s new method is a form of directional recrystallization — a heat treatment that passes a material through a hot zone at a precisely controlled speed to meld a material’s many microscopic grains into larger, sturdier, and more uniform crystals.
“In the near future, we envision gas turbine manufacturers will print their blades and vanes at large-scale additive manufacturing plants, then post-process them using our heat treatment,” Cordero says. “3D-printing will enable new cooling architectures that can improve the thermal efficiency of a turbine, so that it produces the same amount of power while burning less fuel and ultimately emits less carbon dioxide.”
Materials Science student
Oxford University
MIT
“We’ve completely transformed the structure,” says lead author Dominic Peachey. “We show we can increase the grain size by orders of magnitude, to massive columnar grains, which theoretically should lead to dramatic improvements in creep properties.”
Cordero plans to test the heat treatment on 3D-printed geometries that more closely resemble turbine blades. The team is also exploring ways to speed up the draw rate, as well as test a heat-treated structure’s resistance to creep. Then, they envision that the heat treatment could enable the practical application of 3D-printing to produce industrial-grade turbine blades, with more complex shapes and patterns.
“New blade and vane geometries will enable more energy-efficient land-based gas turbines, as well as, eventually, aeroengines,” Cordero notes. “This could from a baseline perspective lead to lower carbon dioxide emissions, just through improved efficiency of these devices.”
Cordero’s co-authors on the study are lead author Dominic Peachey, Christopher Carter, and Andres Garcia-Jimenez at MIT, Anugrahaprada Mukundan and Marie-Agathe Charpagne of the University of Illinois at Urbana-Champaign, and Donovan Leonard of Oak Ridge National Laboratory.
This research was supported, in part, by the U.S. Office of Naval Research.
Watch this video from Thomas to see a visual of some of the heat treating advances.
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Trevor Jones President Solar Manufacturing, Inc. Source: Solar Manufacturing, Inc.
A vacuum furnace manufacturer in North America has acquired purchase orders for ten vacuum furnaces this 3rd quarter. The furnaces will be shipped to companies in the following market sectors: aerospace, commercial heat treating, and additive manufacturing.
Solar Manufacturing Inc. is based out of Pennsylvania, and the new systems will be sent to locations throughout North America. The various types of new furnace orders ranged in size from the compact Mentor® and Mentor® Pro series to a large production furnace with a work zone of up to 72” in length.
“[S]trong quotation activity levels seem to indicate customers are optimistic to expand after the pandemic ramifications continue to ease," commented Trevor Jones, President of Solar Manufacturing.
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