SINTERING POWDER/METAL TECHNICAL CONTENT Archives

Water Electrolysis for Hydrogen Production Facilitates Decarbonization

The thermal processing industry is a good example of how the on-site production of hydrogen by water electrolysis can be beneficial for many of its processes and for reducing the CO₂ of its plants. In today’s Technical Tuesday, David Wolff, industrial sales director at Nel Hydrogen, discusses how, from plasma spray to metal AM binder jet to annealing at rolling mills, industries across medical, automotive, and beyond are looking to water electrolysis for hydrogen production.

This informative piece was first released in Heat Treat Today’s December 2024 Medical & Energy Heat Treat print edition.

Hydrogen atmospheres are widely used in high temperature thermal processing, including annealing, brazing, PM, MIM, and binder jet AM sintering, metal-to-glass sealing, and related processes such as thermal spray. Hydrogen helps heat treaters achieve acceptable product characteristics. It’s used as a very powerful reducing agent, and it actively cleans surfaces as compared to inert gas atmospheres which only displace oxygen.

Relative to hydrogen’s use in helping plants decarbonize, it’s a fact that major OEMs buying heat treating services and heat treated products are demanding that their suppliers report their decarbonization progress. To meet the needs, hydrogen generation is becoming ever more compelling to heat treaters to ensure hydrogen for atmosphere needs inside the plant, and to help minimize their carbon footprint.

The Clean Energy Supply Conundrum

Most U.S. heat treating facilities get their atmosphere components delivered by truck. The truck emits CO₂ and the hydrogen on that truck is likely “gray” hydrogen made from natural gas. Hence, the carbon footprint from their hydrogen use is notable. Importantly, the electricity grid operators are actively seeking ways to enhance the business success of providers of low carbon electricity. The key issue with those providers — solar, wind, hydro, and nuclear — is that they cannot easily follow the ups and downs of demand. Instead, consumers get electricity from those resources when the wind is blowing, the sun is shining, or the river is high. In the case of nuclear plants, they preferentially run at near fixed output, day and night. They run continuously regardless of demand. As the grid demand is very low at night, they get very low prices for the electricity they generate. They only make money for 12 or so hours a day. That’s why a lot of nuclear plants are threatening shutting down for economic reasons.

Taking Advantage of Low Demand Period Energy Prices for Use During High Demand Hours

Consider this scenario: What if a client with electrolysis capacity to produce hydrogen, such as a heat treater, could buy electricity at lower nighttime prices to make the hydrogen it needs during the day shift for its various processes, perhaps even heating their furnaces? The clean energy provider would be pleased to have more income during its low demand, low price times. The heat treat plant is happy saving money buying decarbonized electricity at low demand prices to make clean hydrogen for its various thermal processes and to operate its furnaces. And, the heat treat company’s OEM clients demanding decarbonization are satisfied, too.

How To Get Started

The scenario described above is a practical and real one for the heat treat industry today. Nel Hydrogen recommends that a heat treat company begin with a plan. That plan may comprise several phases. It’s important to seek out a knowledgeable hydrogen partner in this endeavor to specify exactly what’s needed. For heat treat applications, users generally would want compact equipment, extreme hydrogen purity, load following, near-instant on and instant off, and sufficient hydrogen pressure that make it flexibly suited for a variety of thermal processes, and for hydrogen storage addition at a later time if desired.

Figure 1. Compact hydrogen generators using water electrolysis for thermal processing applications (Source: Nel Hydrogen)

Both batch and continuous processes can be served. Batch processes may benefit from a small amount of surge storage at the outset. By combining on-site hydrogen generation with a small amount of in process hydrogen surge storage if needed, on-site hydrogen generation can be used to meet the needs of batch processes such as batch furnaces and thermal spray. By carefully choosing generation rate and pressure, and surge storage vessel volume and pressure capacity, the combination of generation with surge storage can provide maximum process flexibility while minimizing the amount of hydrogen actually stored.

The presence of a small amount of hydrogen surge storage also protects clients’ parts in case of an electric interruption that stops hydrogen production. The surge storage hydrogen can protect the parts while they cool under a reducing atmosphere.

In practice, specific client priorities such as minimum hydrogen storage, or lowest system capital cost, or highest degree of expandability, or least amount of space occupied, can be met by choosing the specific hydrogen generator capacity and surge storage system employed for any particular production challenge.

Examples of Thermal Processors Producing Hydrogen On Site with Water Electrolysis

Decarbonization will be a near-future requirement as part of the global effort to evolve towards a cleaner, greener world. On-site hydrogen generation in industry makes great sense to align with those initiatives. Right now, the thermal processing industry is experiencing the benefits of producing hydrogen on site for its production processes, and the decarbonization demand will be easier to accommodate with that infrastructure in place.

Here are a few examples of companies performing a variety of thermal processes that have made the decision to use water electrolysis to produce hydrogen on site:

Plasma Spray of Cast Iron Cylinder Liners

One of the most compelling examples has been implemented by two different U.S. automakers to accommodate the increasing use of low-weight aluminum engine blocks in today’s high efficiency vehicles. Aluminum blocks must have a cast iron lining on the inside of the cylinder bore to maximize the durability of the engine. (Older readers may recall the notorious Chevy Vega that used an aluminum engine without a cast iron liner. The author’s wife had one Vega which burned through three engines!)

Figure 2. Plasma torch used to spray-apply metal coatings in additive manufacturing processes (Source: Shutterstock)

The traditional approach to provide a cast iron liner was to drive a sleeve into the aluminum engine block. However, a new technology has been commercialized by which the cast iron liner is spray-applied using a plasma torch. The torch uses hydrogen and argon gases to add energy and maintain the necessary low oxygen atmosphere. The plasma spray was a new addition to engine production facilities that had not previously been equipped with hydrogen supply and thus elected to generate their own to minimize delivered hydrogen and avoid the need for hydrogen inventory and extensive supply piping.

The electrolyzers recommended for plasma spray applications are compact and produce high purity hydrogen of better than UHP grade at 200+ psig pressure, with less hydrogen stored than would fill a party balloon bouquet. About the size of a washing machine or refrigerator, depending on the model, each unit is low maintenance, compact, quiet, and can be installed nearly anywhere in a facility.

Metal Additive Manufacturing (AM) Binder Jet

One of the most exciting approaches to metal AM is the technology called binder jet, which creates a near net shape part using polymer and wax binders to adhere metal powders. After the part is formed, the binders are chemically or thermally removed. Then the part is sintered to attain near net shape and full part density. Hydrogen is required for the sintering atmosphere to prevent oxidation of the part during the sintering process. Binder jet technology promises to provide for mass production of individually customized parts at high production rates and consequently lower costs than parts produced individually.

Figure 3. Binder jet metal AM parts sintered in a hydrogen atmosphere (Source: Shuttershock)

Many new metal AM production facilities are being established in factories that are not already equipped for the delivery, storage, and internal piping/distribution of hydrogen. As such, many have chosen instead to use zero inventory hydrogen made on site to minimize infrastructure investments. Electrolyzers for small-scale applications requiring up to 230 scf/hr of hydrogen gas at 99.999+ % purity are advised for metal AM. About the size of a large refrigerator, the units require minimal facility floor space, are easy to maintain, and can be installed in any non-classified space. Applications for AM include medical, electronics, industrial, and automotive components.

Annealing at Rolling Mills

Plate and strip metal are processed in rolling mills where the thickness of the metal is reduced by alternating “cold” rolling steps followed by intermediary hot annealing steps. Cold rolling makes the metal more brittle, so it is necessary to have an annealing step following each rolling step. The metal is alternately thinned and then softened for what could be several iterations. Hydrogen is required for the annealing steps to maintain metal surface quality while heated. Because of the periodic market disruptions in delivered hydrogen from plant outages or trucking interruptions, several rolling mills have chosen to generate hydrogen on site to augment or entirely replace their delivered hydrogen supply. The benefits that the plants experience are primarily focused on supply reliability. Of course, they are also eliminating the carbon footprint associated with truck delivery. In this case, the carbon footprint of the generated hydrogen is determined by the particular electricity generating mix that serves the plant site.

Most often at rolling mills, electrolyzers that produce up to 1,140 scf of hydrogen gas at 99.999+ % purity are best suited for the hydrogen requirement. These units replace the need for hydrogen tube trailers or liquid hydrogen storage. They can be installed in the mill or can be containerized outdoors, offering flexible siting and reduced operational safety risks compared to delivered hydrogen.

Figure 4. Steel rolls are heated in an annealing step to soften the metal during production. (Source: Istock)

On Track Towards Decarbonization

Described in the examples above, once the means to generate hydrogen is chosen at a thermal processing facility, the company can move further along the decarbonization journey. This may be to apply a strategy as outlined in the electricity scenario whereby the company takes advantage of low demand rates or institutes an alternative creative idea. Certainly, as more and more clients demand proof that suppliers are reducing their carbon footprint, more strategies will be developed and implemented to serve the thermal processing industry. Simply generating hydrogen on site removes the trucking emissions factor and is a beneficial and practical starting point.

About the Author:

David Wolff
Eastern Regional Sales Manager
Nel Hydrogen

David Wolff has 45 years of project engineering, industrial gas generation and application engineering, marketing and sales experience. He has been at Nel Hydrogen for over 25 years as a sales and marketing leader for hydrogen generation technologies.

For more information: Nel Hydrogen at sales@nelhydrogen.com.

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Fueling Efficiency: Retrofit Heat Treat Furnace with Combustible Burner Technology

August 27, 2024 / AUTOMOTIVE HEAT TREAT TECHNICAL CONTENT, BURNERS & COMBUSTION SYSTEMS, SINTERING POWDER/METAL TECHNICAL CONTENT

The automotive industry is going electric — electric vehicles are a popular choice for consumers. To continue sustainable efforts for a healthier planet, heat treaters need to seriously consider energy recovery technologies for their equipment and processes. In this Technical Tuesday article, Harb Nayar, founder, president, and CEO at TAT Technologies, examines the use of combustible burner technology (CBT), specifically CBT technology retrofitted on conveyor furnaces that utilize some level of combustible produced by synthetic or generated atmospheres, and that have peak temperatures above 1400ºF (760ºC).

This informative piece was first released in Heat Treat Today’s August 2024 Automotive print edition.

Annealing, brazing, and even powder metal (PM) sintering, metal injection molding, and additive manufacturing offer the automotive industry components with the precision to meet their demanding standards. For example, the nature of PM manufacturing produces minimal waste, both from a material and an environmental perspective. But most in-house and commercial heat treaters fail to capture and reuse energy or convert emissions with environmentally unfriendly pollutants by use of efficient and available gas-neutralizing equipment. These devices capture and thermally combust hydrocarbons, carbon monoxide, and noxious gases such as ammonia.

Figure 1. CBT unit (model based on LBT-I unit)

The reality is that rather than just neutralize these emissions, heat treaters can use them to heat their parts, even before preheating. The focus of this article is to examine the use of combustible burner technology (CBT) and more specifically, CBT technology retrofitted on conveyor furnaces for processes that has the following:

Have peak temperature above 1400ºF (760ºC).
Utilize some level of combustible (e.g., H₂, CO, and CH₄) produced by synthetic atmospheres (e.g., N₂-H₂) or generated atmospheres (e.g., Exothermic, Endothermic and dissociated ammonia).

Here’s a 20-second video of “dancing” flames exiting a conveyor furnace that is sintering PM parts in a N2-H2 atmosphere at 2050°F (1,000+ lb./hr.). Source: TAT Technologies

Recovering Latent Heat Energy

A typical conveyor furnace found on the shop floor has three distinct zones, a preheat zone, a high heat zone, and a cooling zone. Since it is desirable in these units to have a forward atmosphere flow (toward the entrance end of the furnace and opposite the direction of part travel), combustibles emitted while processing the parts exit at the entrance and are typically burned off before entering the room or exhaust system. Often, flames can be seen burning at the front of the furnace.

Combustible burner technology, aka lubricant burner technology (LBT), is a thermal technology that was originally developed to address issues in the PM industry (Figure 2). This technology can be supplied with or retrofitted on the front of a conveyor furnace to recover latent combustion energy from combustibles (e.g., H₂, CO, CH₄) or hydrocarbon vapors (e.g., wax lubricants used for PM parts). The energy can be reused to heat parts before entering the preheat zone. This means that the preheat zone itself can be significantly shortened.

Retrofit Example — PM Sintering Furnace

PM processing is very specific and often more difficult to adopt compared to other continuous atmosphere furnaces. Given the large percentage of PM parts used by the automotive industry, it offers a good example of how heat treaters can achieve energy and cost savings via energy recovery technology.

A Close Look at the Process

Sintering is commonly performed in continuous atmosphere furnaces. In the sintering process, powder metal is combined with a binder, often solid wax (Acrawax^®) or stearate-based lubricants are used in the compaction process to make green parts. Delubrication (aka delube, debindering) then takes place in the preheat section of the furnace. There are three phases during PM sintering:

Typical door-to-door time varies between one to five hours, depending upon the material being sintered.

The most common atmosphere used in sintering processes is N₂ with 7–20% H₂. In other shops, the atmosphere used is Endothermic gas, which has (approximately) 40% H₂, 20% CO, with the balance primarily N₂ or dissociated ammonia (DA) with a composition of 75% H₂ and 25% N₂. In some sintering operations, a mixture of DA and N₂ is used.

The atmosphere with all the combustibles travels from the high heat section to the preheat section and finally exits from the front of the furnace where the various pollutants are burned off before entering the exhaust system. The total amount of combustibles varies between 10% and 50% depending on the type of atmosphere and material being sintered.

For example, CBT units have been installed for the delubing of tungsten-based alloy parts prior to sintering in high temperature pusher furnaces.

Figure 3. CBT unit called “LBT-I.” (Left) main body before installation and (right) control panel. Source: TAT Technologies

Capturing Latent Energies

During the PM sintering process, users can capture this latent heat to transfer this energy into the green parts prior to the preheat section. The following are approximations of the latent combustion energy available:

H₂: approximately 0.1 KW per cubic foot of H₂ or 0.35 KW per cubic meter of H₂
CO: approximately 0.12 KW per cubic foot of CO or 0.4 KW per cubic meter of CO
Wax lubricant: approximately 5 KW per lb. or 11 KW per kg of lubricant going into the furnace

How CBT Works

The CBT unit retrofits to the flange of the preheat muffle of the sintering furnace. In its reaction chamber, the furnace atmosphere gases enter from the heating sections carrying the various combustibles. These are circulated in the chamber in which preheated air at 1000–1600°F is introduced through vents in the roof of the chamber (Figure 1).

When the furnace atmosphere and air mix, a combustion reaction takes place with flames being produced over the incoming load of parts that are traveling on the belt towards the preheat section. Heat from theses flames helps vaporize the lubricant and any oils present at a high rate. The lubricant vapors flowing out of the parts are instantly and continuously consumed within the CBT chamber before leaving to enter the exhaust system in the front of the furnace. However, the energy released from the burning lubricants and oil vapors remains, adding to the energy from combustion within the CBT chamber. Enough total heat is generated to heat the parts and the belt to temperature above 930ºF (500ºC) before entering the preheat section. This “recovered” heat energy is essentially free as it is generated from the combustibles and lubricant and oils (e.g., H₂ for oxide reduction and lubricant for ease of compaction).

Figure 4. Illustration of the energy generated within the CBT reaction chamber. Parts are moving from right to left. Source: TAT Technologies

Another Case Study Illustration

Energy recovery in a CBT reaction chamber from fully combusting H₂ coming from the preheat section of the furnace at a flowrate of 400 CFH (11.3 m3/h) and lubricant coming with the green parts at a rate of 7.2 lbs (3.3 kg) per hour is approximately 235,000 Btu/hr (248 MJ/hr) which is equivalent to an energy savings of approximately 70 KWh of electricity.

Additional Heat Treat Applications

Many other heat treating processes benefit from CBT technology. Some examples follow next.

Annealing often utilizes continuous furnaces.

The percentage of H₂ in the atmosphere is generally much higher — in some cases 100%.
Materials and annealing practices vary from plant to plant.
Prior to annealing, the material often has surface oxidation and/or some type of coating (e.g., oils, dry lubricants).
The goal is to avoid decarburization and produce an acceptable microstructure, which highly depends on the time/temperature cycle.

Brazing is another thermal process that benefits from CBT technology.

Brazing of most automotive parts is done in either in Exothermic or Endothermic gas or N₂-H₂ or H₂-Ar atmospheres.
Materials being brazed are typically low carbon steels or stainless steels. In some instances, other special materials are used.
The goal is to have clean, oxide, and soot-free joint surfaces just before the filler metal (commonly copper or nickel-based alloys) melts, flows into the gap between the parts by capillary action, and solidifies producing a homogeneous part.

Summary

Figure 5. Photo shows the main body of a CBT unit. Different product models vary in length and flow capacity, but all produce improvements in product throughput up to 25–50%. Source: TAT Technologies

Heat recovery units like CBT are essential for not only neutralizing harmful furnace gases but oils or other types of organic compounds. This technology allows latent heat energy to be utilized, increasing efficiency and saving energy. Benefits include:

Emission control. Using combustion technology, heat treaters are able to convert potentially harmful pollutants from reaching the exhaust system.
Increased productivity. The technology increases throughput up to 50% depending upon the model used since incoming parts are heated prior to entering the preheat section of the furnace.
Energy savings. The power requirements in the preheat section are reduced and throughput increases up to 50% depending upon the model used.
Improved heat transfer. Parts can be heated to a higher temperature in a shorter amount of time for faster removal of organic materials prior to subsequent reduction of metal oxides.
Decreased unit cost. The energy consumption is lowered and overall cost of parts produced in reduced.
Environmental benefits. Ambient temperature in the front-loading area by 10–30°F is lowered since the burn off flames are significantly smaller. Processes being run are less sensitive to air infiltration in the vicinity of the furnaces.

About the Author:

Herb Nayar
President & CEO
TAT Technologies
Source: TAT Technologies

Harb is an inquisitive learner and dynamic entrepreneur who will share his current interests in the powder metal industry, and what he anticipates for the future of the industry, especially where it bisects with heat treating.

For more information: Contact Harb at harb.nayar@tat-tech.com.

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Sintering Considerations: Vacuum vs. HIP

May 15, 2024 / HIPING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT, MANUFACTURING HEAT TREAT TECH, SINTERING POWDER METAL, SINTERING POWDER/METAL TECHNICAL CONTENT, VACUUM FURNACES, VACUUM FURNACES TECHNICAL CONTENT

Source: TAV Vacuum Furnaces

When processing cemented carbide, there are a few considerations you need to understand to use the proper sintering equipment. One of the biggest factors is the actual material; what is the colbalt content level of the processed material?

In this best of the web article, walk through the steps of dewaxing, sintering for appropriate densification, and the processing temperatures that are required for sintering cemented carbide.

An Excerpt:

“Other than mechanical stresses due to the differential pressure between inside and ambient pressure outside the furnace, operating at relatively high temperatures with high pressure of gas would lead to significant dissipations of heat to the external environment. This is not only anti-economic from an efficiency point of view, but could also compromise the structural integrity of the water-cooled steel vessel of the furnace by overheating it.”

Read the entire article from TAV Vacuum Furnaces, written by Giorgio Valsecchi, by clicking here: “SINTERING OF CEMENTED CARBIDE: A USER-FRIENDLY OVERVIEW – PT.2“

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Heat Treating AM Components to Infinity and Beyond

May 9, 2024 / AEROSPACE HEAT TREAT, AEROSPACE HEAT TREAT TECHNICAL CONTENT, MANUFACTURING HEAT TREAT, MANUFACTURING HEAT TREAT TECH, SINTERING POWDER/METAL TECHNICAL CONTENT

The amazing materials that are produced through additive manufacturing (AM) and 3D machining often require post-processing heat treatments before these become final components that launch into space. What are the trends of AM/3D outside our planet, and what technical resources are available to you as you make one step into this field? This original content piece from the Heat Treat Today editors will help you understand where technology stands in 2024.

Why Does AM/3D Go to Space?

A broad spectrum of industries have found the appeal of additively manufactured parts, industries ranging from mining to medical and automotive to space. Much of this has to do with complexity of components that new engineering techniques require, the desire to save on material costs, and the ability to condense lead time. For some, additive manufacturing is becoming essential to the space industry; as Tobias Brune, head of the Business Unit Additive Manufacturing at TRUMPF, has commented, “With our 3D printing technology, we are driving the commercialization of the space-travel industry. If you want to be successful in the space-travel industry today, you have to use additive manufacturing.”

When should you expect this transition? Now.

In January of this year (2024), the first metal 3D printer for space was launched to the Columbus module of the International Space Station (ISS). This is a very active, integrated sense of seeing AM in the aerospace industry, and test runs with this equipment will ensue.

Flight model of 3D Metal Printer Launched on NG-20
Source: ESA

The Exploration Company in Europe plans to use 3D printers from TRUMPF (laser specialist) to print core components in engines for spacecrafts. The intent: missions in Earth’s orbit and to the moon.

Heat Treat & thermal Processing Requirements of Post-Processing AM

If you are going to get involved in AM, it is essential to have the right equipment. One of the most talked about equipment is hot isostatic pressing (HIP) technology. Often, heat treat operations use HIP equipment for post-process heat treating in order to get the solid part they desire. For the most part, commercial heat treaters have positioned themselves to handle the R&D required to navigate the terrain of overcoming processing challenges of new/complex parts and creating standardizations. However, private R&D facilities and departments are also building out their capabilities to handle AM in HIP.

However, so also have vacuum furnaces been a key leader in heat treating AM components. Here, commercial heat treaters have also made moves to expand their equipment/process offerings to accommodate AM parts.

So also do atmosphere considerations need to be considered, with gasses like H2 competing trying to capture the limelight.

Continue the Exploration: AM/3D Articles for Space

Looking for an introduction to the AM/3D topic for heat treaters? Begin with this article by Animesh Bose, an engineering pioneer: “The Role Of Heat Treat in Binder Jetting AM for Metals.” The article uncovers the history of one of the most important types of AM/3D manufacturing — binder jetting AM.

Then, take a step over for an industry focus on what “heat treatments for space” look like. Mike Grande eloquently summarized the current processes needed in space in this editorial from the March 2024 Aerospace print edition. Read “The Role of Heat Treatment in Space Exploration” in the digital edition of the magazine.

In-house or commercial? This article presents critical considerations of space components — with a particular emphasis on the importance of AM/3D — when considering how to grow your processing expertise and capabilities. Several examples from the frontlines of R&D are presented by Noel Brady in his article. Read the editorial, “Thermal Processing for Space and Additive Manufacturing,” for excellent illustrations.

Finally, hone in on the topic with a case study about developments in HIP technology for space component post-processing. This article begins with context confronting issues of structural integrity, especially of complex space components, with HIP. Andrew Cassese gets to the case study towards the end of his article, “High Pressure Prepares Parts for Space.”

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Thermal Processing for Space and Additive Manufacturing

April 9, 2024 / AEROSPACE HEAT TREAT, AEROSPACE HEAT TREAT TECHNICAL CONTENT, FEATURED NEWS, HIPING TECHNICAL CONTENT, SINTERING POWDER/METAL TECHNICAL CONTENT

The race to space is in full swing with public and private sector companies staking their claim in this new frontier. And breakthroughs in technology and materials offer the potential to propel humanity to unprecedented distances. Success hinges not only on the ability to discover novel solutions but also on the capacity to prepare those solutions for efficient, large-scale production.

This Technical Tuesday article by Noel Brady of Paulo was originally published in Heat Treat Today’s March/April 2024 Aerospace print edition.

Space Today: Making Life on Earth Better, Safer, and More Connected

Noel Brady, Metallurgical Engineer, Paulo
Source: Paulo

According to NASA, 95% of space missions in the next decade will stay in low Earth orbit (LEO) and geostationary orbit (GEO). Th at means the first wave of commercial activity in space will be largely focused on making life on Earth better.

Several worldwide broadband satellites are already in orbit, offering more consistent, reliable internet signals around the globe. Defense campaigns are using advanced satellite machine learning to improve asteroid and missile detection, along with revolutionary laser technology that has made intersatellite communication possible for the first time — and the travel of information faster. And to help make
life in space safe and successful, NASA is developing a scalable network of public GPS receivers for easy, short-range space navigation and tourism.

All this to say, parts are being developed for a wide range of applications, a huge portion of which are being additively manufactured.

Thermal Processing Standards Necessary for AM Adoption

However promising additive manufacturing is for space, the adoption of AM has still been limited due to the lack of standards for proprietary material and 3D printing applications. Many thermal processing experts are joining research institutions and OEMs in the drive to bring AM into mainstream manufacturing with new industry standards and production-ready solutions that help achieve ROI.

The R&D process for discovering these standards can be lengthy and expensive because it requires trial and error. A prototype or small run of parts must be manufactured, then heat treated, and tested for the desired properties. If a test part’s yield strength is not where it should be, for example, then the heat treating recipe is adjusted, perhaps by lowering the temperature and increasing the pressure, and can be tested again on a new batch of parts.

Coach vs. Custom Cycles

In heat treating, there are two different types of cycles, and it’s important to know the difference when you’re working with any commercial heat treater. Coach cycles tend to be more economical because these are shared cycles — existing recipes that are in high demand and run on a regular schedule — with the potential to have multiple clients’ parts in the furnace at once. For example, a heat treater may have a standard titanium coach cycle they run once a day. See Table A for several coach cycles run at Paulo.

Table A. Example of Coach Cycles for Space Alloys

Coach cycles use recipes that were designed for cast parts and have been around since before additive was a viable form of manufacturing. While it’s true that cast parts and AM parts have similarities, such as their high porosity, it doesn’t mean that the recipes are optimal for preparing today’s parts for heavy space applications. That’s where custom cycles come into play.

Custom cycles are ideal for new or proprietary materials that don’t yet have recipes defined or that are not commonly heat treated enough to run on a regular schedule. The distinction between the two is important because not all heat treaters are equipped to run both types. While you may be able to find a coach recipe that gets you close to where you need to be, it certainly may not be optimal, especially for parts that will have a heavy life of service.

Heat treaters with flexibility of custom and coach cycles, along with full-cycle data reporting, offer a high level of control that is vital for helping the industry progress and scale for production. This is also a big reason why some in-house heat treating operations may choose to outsource some of their work: first collaborating with experienced commercial heat treaters to prove the specification for a new part with custom cycles before scaling for production.

Common Cycle Adjustments for AM

There are five primary parameters that can be adjusted in the heat treating of AM parts to achieve the desired results: temperature, pressure, time, cooling rate, and heating rate. For AM parts, adjustments to the temperature and pressure are a go-to for achieving parts with higher yield strength. For example, running a cycle 50°F cooler, but at 5 ksi higher pressure may yield better results.

There may also be certain heating ramp rates and intermediate holds before parts get to the max temperature, to allow for consistent heating and enhance the material properties. The same goes for the cooling process: controlling the rate at which a part cools with specific holding times and intermediate quenches.

Hot Isostatic Pressing, Space, and Additive Manufacturing

Hot isostatic pressing (HIP) combines high temperature and pressure to improve a part’s mechanical properties and performance at extreme temperatures. The sealed HIP vessel provides uniform pressure to bring parts to 100% theoretical density with minimal distortion. The high level of control and uniformity has made HIP the gold standard for AM parts for space.

Similar to cast parts, 3D-printed materials tend to have porous microstructures that can compromise part performance. HIP is the only process that’s able to eliminate these pores without compromising the complex geometries and near-net dimensions that are achieved in the printing process.

Benefits of HIP for space parts include the following:

Better fatigue resistance
Greater resistance to impact, wear, and abrasion
Improved ductility

For this process, Paulo’s Cleveland division is equipped with a Quintus QIH-122 HIP vessel, which is specially modified with additional thermocouples for more precise temperature control and greater data collection. A higher level of accuracy allows us to iterate with confidence and find an efficient path to production-ready development.

One primary benefit of the Quintus QIH-122 HIP is the ability to have faster cooling at a controlled rate, which allows you to heat treat and solution treat in one furnace. This cooling rate allows great efficiency that cannot be seen with other HIP vessels on the market.

It is critical that heat treaters adapt to meet the needs of this fast-evolving industry. Many commercial heat treaters do not yet have the level of data or dynamic cycle offerings necessary and will only run HIP coach cycles with set parameters. In other words, many are not equipped to economically iterate and adapt heat treating recipes for new parts. Without custom cycles, controlled cooling, and a higher level of data, it is impossible to push the boundaries of what’s possible.

Space Parts Requiring Thermal Processing

The future of space travel requires parts that can not only perform under high levels of mechanical pressure and extreme temperatures but are also durable enough for long-range and repeat missions. Heat treatment is a critical step in preparing rocket engine components, among others, for commission. Other space components commonly heat treat treated are:

Volutes
Turbine manifolds
Bearing housings
Fuel inlets
Housings, support housings
Bearing supports
Turbo components

Since the inception of NASA’s Space Shuttle Program, Paulo has treated integral components for launch and propulsion, along with many parts currently in orbit on the International Space Station.

Materials Used in Space Parts

New materials and applications are being explored every day. Proprietary alloy blends bring unique properties and promising potential in the push for stronger, faster, longer-lasting parts. But with unique properties comes the need for unique heat treating processes. Several high-performance superalloys used for space include:

Inconel 718, 625
Titanium (Ti-6Al-4V)
Hastelloy C22
Haynes 214, 282
GRCop Copper

Inconel 718, a championed space alloy, was originally used as a premier casting material before being adopted for AM. This nickel-based material features an extremely high tensile and yield strength that makes it ideal for components taking on a high mechanical load in extreme environments ranging from combustive to cryogenic — making this a natural material to adopt for space in the early days of 3D printing.

Because casting and 3D printing both result in similar porous microstructures, the heat treating process used for Inconel castings could also be adapted. Finding new opportunities within existing alloys like this is a highly efficient way to gain material advantage in today’s race to space.

To learn more about adapting alloys and heat treating processes for AM parts, download the full space guide.

About the Author

Noel joined Paulo in 2011 and spent several years as quality manager before stepping into his current role as a metallurgical engineer. Noel holds a bachelor’s degree in engineering and metallurgy materials science, and he is responsible for thermal process development and hot isostatic pressing process development.

For more information: Contact Noel Brady at nbrady@paulo.com or visit this link to download the full space guide from Paulo.

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An Overview of Cemented Carbide Sintering

February 5, 2024 / FEATURED NEWS, HIPING TECHNICAL CONTENT, MANUFACTURING HEAT TREAT NEWS, PARTS CLEANING TECHNICAL-CONTENT, SINTERING POWDER/METAL TECHNICAL CONTENT, TITANIUM PROCESSING TECHNICAL CONTENT, VACUUM FURNACES TECHNICAL CONTENT

Source: TAV Vacuum Furnaces

Cemented carbide is often used interchangeably with other terms in the industry to describe a popular material for tool production. However, the specifics of what makes up a cemented carbide, and how this material can be processed, are not so widely discussed.

In this best of the web article, discover the composition, applications, and processes involved in sintering cemented carbide, as well as how vacuum furnaces play an essential role for this material. You will encounter helpful diagrams and resourceful images depicting each step of the process.

An Excerpt:

“Hard metal, or cemented carbide, refers to a class of materials consisting in carbide particles dispersed inside a metal matrix. In most cases, the carbide of choice is tungsten carbide but others carbide forming element can be added, such as tantalum (in the form of TaC) or titanium (in the form of TiC).
The metal matrix, often referred as ‘binder’ (not to be confused with wax and polymers typically used in powder metallurgy) is usually cobalt, but nickel and chromium are also used. This matrix is acting as a ‘cement,’ keeping together the carbide particles (hence the ‘cemented carbide’ definition).”

Read the entire article from TAV Vacuum Furnaces, written by Giorgio Valsecchi, by clicking here: Sintering of Cemented Carbide: A User-Friendly Overview- Pt. 1

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The Role of Heat Treat in Binder Jetting AM for Metals

January 10, 2023 / FEATURED NEWS, MANUFACTURING HEAT TREAT, SINTERING POWDER/METAL TECHNICAL CONTENT

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.

For more information: Contact Animesh at animeshbose53@gmail.com

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Corrosion Behavior of DMLS Titanium Alloy for Orthopedic Applications

December 20, 2022 / FEATURED NEWS, HIPING TECHNICAL CONTENT, MEDICAL HEAT TREAT, MEDICAL HEAT TREAT TECHNICAL, SINTERING POWDER/METAL TECHNICAL CONTENT, TITANIUM PROCESSING TECHNICAL CONTENT

In this article, explore the importance of alternative advanced manufacturing processes and the effects of post-process heat treating of DMLS titanium alloy parts. In a recent study, a team at Worcester Polytechnic Institute (WPI) evaluated the effects of these processes. Read along to see what they found.

This Technical Tuesday article was first published in Heat Treat Today's December 2022 Medical and Energy print edition.

Jianyu Liang
Professor of
Mechanical and Materials Engineering
at Worchester Polytechnic Institute
Source: WPI

According to Markets and Markets reports, the metal implants and medical alloys market¹ will reach $17.64 billion by 2024, at a CAGR of 9.4%, with titanium metal implants and medical alloys accounting for the largest share of the market. Since it was first reported in the 1940s that titanium had excellent compatibility with human bones, titanium has been used in a wide range of biomedical applications, including arthroplasty and bone replacement, prostheses, craniofacial, maxillofacial, and dental implants, as well as surgical instruments and healthcare goods.^2,3

Although Ti-6Al-4V alloy was originally developed for aerospace applications, its many attractive properties — such as high strength-to-weight ratio, satisfactory biocompatibility, and good corrosion resistance — resulted in it being one of the most widely used biomedical alloys.⁴

However, Ti-6Al-4V alloy is very difficult to machine. Traditional Ti-6Al-4V manufacturing processes include casting, wrought (forging/milling from ingots), and powder metallurgy (P/M), with wrought products accounting for 70% of the titanium and titanium alloy market.⁵

In recent decades, additive manufacturing (AM) processes have been rigorously

Richard Sisson
Key Heat Treat
Researcher and Lecturer at Worchester
Polytechnic Institute
Source: WPI

developed as an alternative advanced manufacturing process for Ti-6Al-4V, especially in personalized biomedical applications. Alternate processes, including powder-bed fusion (PBF), directed energy deposition (DED), and sheet lamination (SL) have been applied in AM processing of titanium and its alloys.⁶ Direct metal laser sintering (DMLS), a PBF technology, was the first commercial 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.⁷ However, even with the protective oxide film (mainly TiO2), titanium alloys still suffer from pitting and crevice corrosion. Localized breakdown of the protective film leads to the formation of pits. These pits can grow and propagate into macroscopic cracks, which lead to catastrophic failure in orthopedic applications.^8,9

It was reported that post-heat treatment of Ti-6Al-4V parts fabricated by AM techniques could improve its mechanical properties, especially increasing ductility and fatigue strength.

Yangzi Xu
Yield & Module
Process Engineer at Intel Corporation
Source: WPI

However, the changes in corrosion behavior with various post-heat treatments of Ti-6Al- 4V parts fabricated by AM techniques have not been fully understood. In a recent study, a team at Worcester Polytechnic Institute (WPI) evaluated the effects of various post-process heat treatments (including solution treatment and aging, annealing, stress relief, and hot isostatic pressing (HIP)), on the corrosion behavior of Ti-6Al-4V parts manufactured by DMLS. The researchers then proposed a desirable posttreatment procedure that can obtain a good combination of mechanical properties and corrosion behavior of as-printed parts in a simulated body environment.^10,11,12

Ti-6Al-4V dumbbell-shaped tensile testing bars were fabricated by DMLS, according to ASTM standards. The microstructure, phase fraction, porosity, and residual stress of as-printed parts were examined and compared to those of the commercial Grade 5 alloy. It was found that the as-printed samples, mainly composed of acicular α’ martensite phase with a small amount of nano-scaled β precipitates, dispersed in the α’ matrix due to rapid cooling during laser processing, whereas the Grade 5 alloy has an α + β two phase with an equiaxed microstructure. The β phase fractions in the as-printed and Grade 5 alloy were 1.6% and 20%, respectively, based on the results of x-ray diffraction refinement. Furthermore, porosity and defects due to lack of fusion or entrapped gas were observed in the DMLS samples. The rapid cooling rate also resulted in residual tensile stress in the as-printed parts.

The microstructure and phase changes due to different heat-treatment processes were examined and compared to those of the commercial Grade 5 alloy. The corrosion behavior of the heat-treated DMLS parts was studied in simulated body fluid by well-established electrochemical methods.

Microstructure: coarsening of the α lath thickness, more spherical β precipitates.
Phase identification: narrowed α characteristic peaks (reduced compressive residual stress)
Source: WPI

Transformation from α’ to α phase, coarsening of the α lath microstructure, and the development of β phase were observed in samples after heat treatments. The greatest fraction of β phase was obtained in the high temperature annealed sample. Enhanced corrosion resistance was found in all heat-treated samples. The reasons for improved corrosion resistance after heat treatments include: 1) a passive layer that was developed on the sample surface after heat-treatments; 2) increased β phase fraction and size after heat treatments that led to the reduction of the corrosion susceptible sites. Furthermore, only a single passive layer has been observed in the as-printed sample, whereas double passive layers have been observed in samples after heat treatments at temperature higher than 550°C. However, this second layer, which was largely composed of Al2O3 and V2O5, had very low corrosion resistance compared to that of the primary passive layer that was primarily TiO2.

Microstructure: coarsening of the α lath, and grain boundary can be observed
Phase identification: narrowing of α characteristic peaks (reduced microstrain, increased grain size) and evolution of β phase
Source: WPI

It was also found that the surface roughness had an exponential effect on the corrosion current density and calculated corrosion rate. A rough surface led to a higher corrosion rate, but a rough surface is known to enhance osteointegration. Therefore, surface roughness needs to be adjusted, based on specific applications.

Microstructure: no significant change in the α lath thickness
Phase identification: narrowing of α characteristic peaks (reduced microstrain), evolution of β phase
Source: WPI

The effect of porosity was analyzed by using a crevice corrosion test. After a one-month immersion in Ringer’s solution at body temperature, pits were found on the Ti-6Al-4V sample surface near the pores in the as-printed samples, which was due to the formation of localized O2 concentration cells near the pore. Porosity in the as-printed parts was confirmed to impair crevice corrosion resistance. To reduce porosity, HIP was applied at three different temperatures. Based on polarization tests and electrochemical impedance spectroscopy tests, different degrees of reduction in porosity and corrosion-current density were observed in samples after HIP; this reduction was most significant after high-temperature HIP at 799°C (1470°F).

In summary, it was found that high temperature heat-treatment enhanced the corrosion resistance of DMLS Ti-6Al-4V parts. HIP was effective in reducing porosity and improving corrosion resistance. HIP below the annealing temperature (799°C, 1470°F) was recommended as a post-treatment for DMLSprintedTi-6Al-4V, to achieve a good corrosion resistance.

References

[1] “Metal Implants and Medical Alloys Market – Global Forecast to 2024,” 2019. https://www.marketsandmarkets.com/Market- Reports/metal-implant-medical-alloy-market-256117768.html.

[2] R. Bothe, et al., “Reaction of bone to multiple metallic implants.” Surgery, Gynecology and Obstetrics, 1940, 71:598–602.

[3] M. Sarraf, E. Rezvani Ghomi, S. Alipour, et al., “A state-of-the-art review of the fabrication and characteristics of titanium and its alloys for biomedical applications,” Bio-des. Manuf., 2022, 5, 371–395. https://doi.org/10.1007/s42242-021-00170-3.

[4] L.-C. Zhang and L.-Y. Chen, “A Review on Biomedical Titanium Alloys: Recent Progress and Prospect,” Adv. Eng. Mater., 2019, 21: 1801215. https://doi.org/10.1002/adem.201801215.

[5] L. E. Murr, S. A. Quinones, et al., “Microstructure and mechanical behavior of Ti–6Al–4V produced by rapid-layer manufacturing, for biomedical applications,” Journal of the mechanical behavior of biomedical materials, 2009, 2(1), 20-32. https://doi. org/10.1016/j.jmbbm.2008.05.004.

[6] A. Hung Dang Nguyen, A. K. Pramanik, Y. Basak, C. Dong, S. Prakash, S. Debnath, I. S. Shankar, Saurav Dixit Jawahir, and Budhi Dharam, “A critical review on additive manufacturing of Ti-6Al- 4V alloy: microstructure and mechanical properties,” Journal of Materials Research and Technology, 2022, 18: 4641-4661. https://doi.org/10.1016/j.jmrt.2022.04.055.

[7] “Direct Metal Laser Sintering (DMLS) Technology,” Additive News. https://additivenews.com/direct-metal-laser-sintering-dmlstechnology/.

[8] O. Cissé, O. Savadogo, M. Wu, and L’H Yahia, “Effect of surface treatment of NiTi alloy on its corrosion behavior in Hanks’ solution.” Journal of Biomedical Materials Research, 2002, 61/ 3 :
339-345. https://doi.org/10.1002/jbm.10114

[9] Sara A. Atwood, Eli W. Patten, Kevin J. Bozic, Lisa A. Pruitt, and Michael D. Ries,”Corrosion-induced fracture of a double-modular hip prosthesis,” The Journal of Bone & Joint Surgery, 2010, 92/ 6: 1522-1525.

[10] Y. Xu, Y. Lu, K.L. Sundberg, et al., “Eff ect of Annealing Treatments on the Microstructure, Mechanical Properties and Corrosion Behavior of Direct Metal Laser Sintered Ti-6Al-4V,” J. of Material Eng and Perform, 2017, 26: 2572–2582. https://doi.org/10.1007/ s11665-017-2710-y

[11] Ibid.

[12] Z. Yang, Y. Xu, R. D. Sisson, & J. Liang, “Factors Influencing the Corrosion Behavior of Direct Metal Laser Sintered Ti-6Al-4V for Biomedical Applications,” Journal of Materials Engineering and Performance, 2020, 29/6: 3831-3839.

About the Authors

Professor Richard Sisson is a key heat treat researcher and lecturer at Worchester Polytechnic Institute. His main research interest is the application of diffusion and thermodynamics to the solution of materials problems. Currently, he is working on modeling the surface treatment of steels and the postprocessing of AM ceramics and metals. His research endeavors have resulted in over 300 publications and over 300 technical presentations.

Dr. Yangzi Xu is currently working at Intel Corporation as a Yield & Module Process Engineer. She received her PhD at Worcester Polytechnic Institute (WPI) and focuses her research on understanding the mechanical and electrochemical properties of AM Ti alloys with different types of heat treatments, and their corrosion performance in biofluid for potential orthopedic applications. Her background includes research in polymer and food science and engineering.

Professor Jianyu Liang is a Professor of Mechanical and Materials Engineering at Worchester Polytechnic Institute, with affiliated appointments in the departments of Civil and Environmental Engineering, Chemical Engineering, and Fire Protection Engineering. Her research work on nanomaterials, AM, agile manufacturing, machine learning for materials science and manufacturing engineering, and sustainability has been funded by NSF, NASA, DoD, ED, and industry. Her work has resulted in over 300 research papers and technical presentations. As an educator, Liang strives to equip students with the confidence, enthusiasm, knowledge, and skills to allow them to enjoy learning throughout their lives.

For more information

Department of Mechanical and Materials Engineering Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609 Or email jianyul@wpi.edu and sisson@wpi.edu

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Heat Treat Future with AM and 3D Printing

November 15, 2022 / FEATURED NEWS, SINTERING POWDER/METAL TECHNICAL CONTENT, VACUUM FURNACES TECHNICAL CONTENT

All the buzz in our industry seems to indicate that additive manufacturing (AM) and 3D printing are the next hot topics in heat treat, particularly in vacuum heat treat. Heat Treat Today decided to find out how these new technologies are shaping the industry. Read what five heat treat industry leaders had to say about how their companies are preparing for the next generation of AM and 3D printing.

This Technical Tuesday article bringing together the responses from these five companies was first published in Heat Treat Today‘s November 2022 Vacuum print edition.

What changes have you made to accommodate the AM/3D printing marketplace?

Dennis Beauchesne
General Manager
ECM USA, Inc.

The most important changes relate to the build plate size and how it connects to our standard size systems. Build plates are ever-changing, it seems, as customers have new applications and mostly larger build plates are being requested. In addition, the process parameters – such as temperature and time at temperature and quantity of material – are important. These two items have the most to do with reconfiguring equipment for the AM market. We have also been able to implement our wide range of automation and robotics skills into this equipment as the market scales up for high production.

How will your products and/or services change to accommodate this marketplace?

We are/will be introducing equipment that is in line with standard-build plate dimensions along with reducing operating costs.

Share how 3D printing or AM products/services help heat treaters.

Recent debind and sinter applications have involved, as previously mentioned, complete robotics to handle parts after printing, to debind, to sinter, and then to process specialized by ECM, such as low-pressure carburizing. ECM has also provided equipment to provide all three processes in the same furnace without moving the load or requiring the furnace to cool and reheat. This reduces work processing time along with less handling and less utility cost.

What changes have you made to accommodate the AM/3D printing marketplace?

Mark Hemsath
Vice President
of Sales, Americas
Nitrex Heat
Treating Services

Nitrex Vacuum Furnaces, through its GM Enterprises acquisition, has moved heavily into additive manufacturing via large production MIM furnaces, which are able to both remove large amounts of powder binders and sinter the parts in the same process. We are in the process of installing and/or starting up five furnaces for these markets, and we have recently employed even more advanced concepts on high volume wax removal. A further trend is on higher value materials, like nickel and cobalt alloys and titanium, necessitating diffusion vacuum levels for processing. Nitrex Vacuum has had this experience already for many years, so moving to smaller scale 3D designs comes with years of experience.

How might your products and/or services change to accommodate this marketplace?

Smaller units are a trend to keep an eye on. We have over a decade of learning from the large units we offer, and this will allow us to compete in these lower volume markets (i.e., 3D) via our proven expertise. Several facts/ideas that we are keeping top of mind are:

Large potential in the future (whole new market starting to evolve)
Redesign the product to meet the new needs
Good for rapid prototyping and quick low volume parts

Furnaces need to be available with fast delivery 3D printing is finding a tremendous niche in fast part production, sourced internally or sourced quickly. These parts may cost more per piece, but having them fast is often more important, and 3D offers this ability to cut weeks or months off of supply chain sourcing.

Share how 3D printing or AM products/services help heat treaters.

The AM sector is still in growth mode. How we help is to give a full-service solution to those customers who want to really increase their volume yet use vacuum in the process. Vacuum helps to transport the binder vapors away from the parts and into the traps for removal. Full binder removal adds to the quality of the parts, as does vacuum sintering of the final parts. We have supplied a few systems over the years with higher, diffusion vacuum levels. As powder materials evolve to higher value materials, there is more interest in diffusion vacuum, and we recently supplied such a system.

What do readers need to know about AM/3D to make decisions today?

Vacuum is the proper way to debind and sinter. Additionally, 3D printing started slow and there were many technologies evolving. Now, it has started to really grow, and the need for smaller furnaces that can offer the same quality as MIM parts produced in high volumes will be a need for 3D part makers, in medium to low volume parts. This may involve furnaces for sinter only, debind and sinter, or even sinter and heat treat. We can see the need to both sinter 3D parts in a small furnace and also heat treat them with special added processes and surface treatments.

What changes have you made to accommodate the AM/3D printing marketplace?

Adding a hot isostatic press has been the most notable change Paulo has made to serve the growing AM market. It goes a step further than that though; heat treatment of AM parts has rapidly evolved, and the desire for custom cycles and more data has caused us to make instrumentation changes and do more R&D type work. Understanding the full production path of the parts and doing our part to reduce the time parts are spending in post-processing steps, including offering stress relief, HIP, EDM, and vacuum heat treatment in a one-stop-shop.

How might your products and/or services change to accommodate this marketplace?

As trials continue and boundaries are pushed for both additive and the accompanying thermal processing, we’re constantly keeping an eye on what’s next. Investing in equipment that’s capable while maintaining and instrumenting it to provide the data and reliability the market needs is the name of the game. Of course, open communication with additive manufacturers and printer designers makes this far easier. We value communication with printer manufacturers as it helps us understand demand for our services in terms of build plate size, since, as we all know, furnaces and HIP vessels aren’t one size fits all!

Share how 3D printing or AM products/services help heat treaters.

Additive parts have become commonplace and we’re now regularly providing HIP, stress relief, and solution treating for them. A more interesting example is for parts printed in Inconel 718; we’ve developed a combined HIP and heat treat (or High Pressure Heat Treat) cycle which was able meet material properties specifications when the traditional processing techniques were not. This is where we feel the real cutting edge is when it comes to heat treatment of additive parts; the slow cooling HIP cycles developed for casting decades ago aren’t always optimal for today’s additive parts.

What changes have you made to accommodate the AM/3D printing marketplace?

Trevor Jones
President
Solar Manufacturing, Inc.
Source: Solar Manufacturing, Inc.

There are several methods for 3D printing and we as heat treaters and vacuum furnace manufacturers generally classify those methods into two basic groups: those that use liquid binding polymers and those that do not.

For the group who does not use liquid binding polymers, there are no changes thus far to the design of the vacuum furnace that must be made. One significant caution is insuring there is no loose powder on the surface or cavities of the parts. Residual powder on or in the parts could have adverse effects on the parts themselves and to the vacuum furnace. The loose powder can liberate from the part during the heat treat or quench steps during the process and contaminate the vacuum furnace. The powder in the furnace is then considered FOD (foreign object debris) for subsequent heat treatments processed in that furnace. The powder could also accumulate over time and cause an electrical ground the heating elements or the quench motor, clog the heat exchanger, contaminate vacuum gauges and hot zone insulation, among other issues.

For the group that does contain liquid binding polymers, in addition to the comments about avoiding loose powder on or in the parts, care must also be taken to accommodate for the vaporization of the binder that occurs during heating of the parts. The binder, in its vapor form, will condense at cooler areas in the vacuum furnace. The condensed areas are potential contamination points and could have all the same issues and concerns of loose powder as described above. The binder collection locations, whether at intentional or non-intentional places, will also have to be routinely cleaned to maintain ideal binder collection, optimum vacuum pumping, and overall furnace performance.

How might your products and/or services change to accommodate this marketplace?

With the growth of 3D printing using liquid binder polymers, Solar Manufacturing has taken what was learned from the furnace modified at Solar Atmospheres of Western PA for MIM and AM processing and applied it to a new furnace product line specific for the debind and sinter applications. Solar Manufacturing collaborated with our affiliate company, Solar Atmospheres of Western PA, in modifying an existing vacuum furnace to accommodate the debind and sintering processes. A modified hot zone was installed, and a dedicated binder pumping port was added that helps minimize and target the condensation of detrimental binders evaporating out of parts containing binders. The modified Solar Atmospheres furnace is extremely valuable in gaining knowledge about various aspects of the process and learning what works, and what does not work, in furnace and recipe design. Combining the knowledge and experience of process development of Solar Atmospheres with the advanced Engineering Design Team at Solar Manufacturing, we believe we have a furnace design that modernizes and simplifies the debinding process while minimizing traditional maintenance issues.

Share how 3D printing or AM products/services help heat treaters.

We developed a process of debinding and sintering stainless steel parts with our affiliate company Solar Atmospheres in Souderton PA. The project started out with our Research and Development group to develop the process for the client’s parts. As the trials scaled up, test coupons became test parts, eventually full-size loads. There are always challenges to scaling up from test parts to production loads and we were able to provide the support the customer needed through that transition. The R&D eff orts were successful, and the client ended up purchasing multiple furnaces, which was the end goal for both parties.

Additionally, Solar Atmospheres is currently vacuum stress relieving a 3D component for a major U.S.-based aerospace company that is in use in aircraft today. Also, numerous large-scale components destined for deep space.

What do readers need to know about AM/3D to make decisions today?

Bob Hill, president of Solar Atmospheres of Western PA, reminded us to “realize and acknowledge that AM is still in its infancy stage. Therefore, many metallurgical uncertainties still exist for the multiple printing processes that exist. Understanding this new kind of metallurgy for each printing process, while developing standards and specifications unique to additive manufacturing, is still a huge obstacle. Until this is accomplished, AM will not be the ‘disruptive’ technology that all the experts predict it will be.” If your business is printing parts with liquid polymer binders, you should seriously consider how you plan on debinding and sintering the parts ahead of time. Printed parts in the “Green” or even “Brown” state are fragile and if you are going to ship the parts somewhere else for the debind and sinter steps, extreme care must be taken to prevent the parts from fracturing during transit. Although the shipping can be safely and successfully accomplished, ideally a furnace is available at the print shop to immediately perform the debind and sinter process to avoid those potential shipping difficulties. The other forms of 3D printing that do not contain liquid polymers generally do have this issue.

What changes have you made to accommodate the AM/3D printing marketplace?

Ben Gasbarre
Executive Vice President
Sales & Marketing
Gasbarre Thermal Processing Systems

From our inception, Gasbarre has had expertise in the powder metallurgy industry, which requires debind and sinter applications similar to that in the AM and 3D printing markets. Our ability to supply equipment for both powder and parts producers has set us up for quick adoption into this market. While considerations need to be made specific to AM, our focus has been on technical support and helping the market grow to higher volume applications.

How might your products and/or services change to accommodate this marketplace?

As adoption of these technologies grow, the volume at which parts need to be produced will grow. Our line of continuous processing equipment in both vacuum and atmosphere applications are well suited. Whether it be debind and sinter, annealing, or stress relieving, we have equipment and expertise that can grow from early production to high volumes.

Share how 3D printing or AM products/services help heat treaters.

Overall, Gasbarre is here to be a resource and support the growth of the additive market. Whether that be through new equipment, servicing existing equipment, or involvement in the industry organizations, we have the expertise to drive success today and into the future!

What do readers need to know about AM/3D to make decisions today?

Additive manufacturing is such a dynamic technology, it is difficult to state one specific item. There is the potential for significant growth opportunities for new applications, but also the potential replacement of traditional manufacturing methods. We also know there is substantial backing for the technology by both private industry and government entities. Like other emerging technologies in the automotive and energies sectors, additive manufacturing isn’t a matter of if, but when it’ll achieve wide scale adoption and high-volume applications.

It is amazing how the list of materials being utilized with this technology is growing. While metals and alloys have not been the majority of the market, it is rapidly growing. With that growth, there is a wide variety of applications and thermal processing requirements for those materials. As well, the different additive and 3D printing processing methods (i.e., binder jetting, powder bed fusion, etc.) leads to a similar diversity in thermal processing requirements.

For more information, contact the leaders:

Dennis Beauchesne, General Manager, ECM USA, Inc. DennisBeauchesne@ECM-USA.COM
Mark Hemsath, Vice President Sales, Furnaces and Heat Treating Services, Nitrex. mark.hemsath@nitrex.com
Phil Harris, Marketing Manager, Paulo. pharris@paulo.com
Trevor Jones, President, Solar Manufacturing, Inc. trevor@solarmfg.com
Ben Gasbarre, Executive Vice President, Sales & Marketing, Gasbarre Thermal Processing Systems. ben.gasbarre@gasbarre.com

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Heat Treat Future with AM and 3D Printing Read More »

Staying Up to Speed with Sintering Parts and Additive Manufacturing for Heat Treat

October 26, 2022 / FEATURED NEWS, MANUFACTURING HEAT TREAT, SINTERING POWDER/METAL TECHNICAL CONTENT

The powder metal industry continues to develop to keep up with production and industry needs. What exactly goes on with powdered metals and additive manufacturing? What is the sintering process? What should heat treaters know about the future of this industry?

In this original content article, three different resources -- an article, a radio broadcast, and a Heat Treat TV episode -- come together to answer these questions and much more.

"Heat Treating, Additive Manufacturing, and Serialization."

Ron Beltz
Director of Strategic Accounts
Bluestreak | Bright AM™

In this article, investigate the processes used to treat the metal powders. Sintering is one such process and others, like annealing and hot isostatic pressing, are examined too. Ron Beltz, director of strategic accounts at Bluestreak | Bright AM’s™ takes a look at these processes and also discusses other elements like software use and serialization. "One of the issues of additive manufacturing is the possibility of internal defects," Beltz explains. "Direct metal laser sintering (DMLS) regularly produces near 100% dense parts, but to provide another level of control to help reduce part failure, hot isostatic pressing (HIP), instead of heat treating, is successfully being used by many aerospace companies and in the casting industry."

Harb Nayar
TAT Technologies
(photo source: tat-tech.com)

Heat Treat Radio #36: "A Discussion with Harb Nayar, Sintering Guru."

Hear from Harb Nayar, president and CEO, TAT Technologies; as he peers into the future of the industry; "The other [change in industry] I think that’s going to emerge is most probably making more and more parts by powder metallurgy from metal powder which are 100% free alloyed." Nayar is confident that the powder metal industry will keep growing, and this interview gives good insights from his depth of knowledge.

Heat Treat TV episode: "Press-and-Sinter Powder Metallurgy."

John Engquist, FAPMI (past president of the Center for Powder Metallurgy Technology), gives some practical basics on what powder metallurgy (PM) is and how sintering helps produce automotive components. "Let's take a look at some PM applications: here we have a notch and pocket plate that are used in one way clutches. . . .made from sinter hardened steel and iron carbon steel. Here we have an automotive planetary carrier system. . . .Here we see stator cores for electric motors . . . ." Listen in on ways to use powdered metal.

These thought-provoking pieces give an opportunity dig a little deeper into sintering and additive manufacturing. Stay on top of education and developments within the powder metal industry.

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Staying Up to Speed with Sintering Parts and Additive Manufacturing for Heat Treat Read More »

SINTERING POWDER/METAL TECHNICAL CONTENT

The Clean Energy Supply Conundrum

Taking Advantage of Low Demand Period Energy Prices for Use During High Demand Hours

How To Get Started

Examples of Thermal Processors Producing Hydrogen On Site with Water Electrolysis

Plasma Spray of Cast Iron Cylinder Liners

Metal Additive Manufacturing (AM) Binder Jet

Annealing at Rolling Mills

On Track Towards Decarbonization

About the Author:

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Recovering Latent Heat Energy

Retrofit Example — PM Sintering Furnace

A Close Look at the Process

Capturing Latent Energies

How CBT Works

Another Case Study Illustration

Additional Heat Treat Applications

Summary

About the Author:

Find Heat Treating Products And Services When You Search On Heat Treat Buyers Guide.Com

Find Heat Treating Products And Services When You Search On Heat Treat Buyers Guide.Com

Why Does AM/3D Go to Space?

Heat Treat & thermal Processing Requirements of Post-Processing AM

Continue the Exploration: AM/3D Articles for Space

Find Heat Treating Products And Services When You Search On Heat Treat Buyers Guide.Com

Space Today: Making Life on Earth Better, Safer, and More Connected

Thermal Processing Standards Necessary for AM Adoption

Coach vs. Custom Cycles

Common Cycle Adjustments for AM

Hot Isostatic Pressing, Space, and Additive Manufacturing

Space Parts Requiring Thermal Processing

Materials Used in Space Parts

About the Author

Find Heat Treating Products And Services When You Search On Heat Treat Buyers Guide.Com

Find Heat Treating Products And Services When You Search On Heat Treat Buyers Guide.Com

Binder Jetting of Metals: Origins

Polymers

Metal AM

Binder Jetting Technology

Heat Treating of AM Metals

Stainless Steels

Low Alloy Steels

Tool Steels

Metal Alloys with Binder Jetting

Future of Binder Jet and Heat Treat

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References

About the Authors

For more information

What changes have you made to accommodate the AM/3D printing marketplace?

How will your products and/or services change to accommodate this marketplace?

Share how 3D printing or AM products/services help heat treaters.

What changes have you made to accommodate the AM/3D printing marketplace?

How might your products and/or services change to accommodate this marketplace?

Share how 3D printing or AM products/services help heat treaters.

What do readers need to know about AM/3D to make decisions today?

What changes have you made to accommodate the AM/3D printing marketplace?

How might your products and/or services change to accommodate this marketplace?

Share how 3D printing or AM products/services help heat treaters.

What changes have you made to accommodate the AM/3D printing marketplace?

How might your products and/or services change to accommodate this marketplace?

Share how 3D printing or AM products/services help heat treaters.

What do readers need to know about AM/3D to make decisions today?

What changes have you made to accommodate the AM/3D printing marketplace?

How might your products and/or services change to accommodate this marketplace?

Share how 3D printing or AM products/services help heat treaters.

What do readers need to know about AM/3D to make decisions today?

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

"Heat Treating, Additive Manufacturing, and Serialization."

Heat Treat Radio #36: "A Discussion with Harb Nayar, Sintering Guru."

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