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).”
Nitriding and nitrocarburizing may be familiar terms in the industry, but which process — ion/plasma nitriding, gas nitriding, or nitrocarburizing — is best for your heat treat operations?
In this best of the web article from Advanced Heat Treat Corp., discover the specifics of each of these surface treatments and compare their benefits for wear resistance and corrosion resistance. Explore also the innovative technologies developed by the North American heat treater for optimization of these processes. for optimization of these processes. You will encounter technical diagrams, high quality images of nitrided/nitrocarburized parts, and in-depth technical comparisons of these processes.
An excerpt:
Well-controlled nitriding significantly enhances wear resistance and lowers coefficient of friction in many applications of steel components. For certain steels, nitrided samples show even better tribological behavior than carburized samples of the same steels.
Those familiar with vacuum heat treatments are surely acquainted with the vacuum heat treatment of titanium and how such furnaces create the ideal environment for titanium's heat treatment. However, not all titanium and its alloys are created equal. Enter the beta titanium alloy.
In this best of the web article from TAV Vacuum Furnaces, discover the potential applications for beta titanium alloys, as well as the effects that various vacuum heat treatments can have on the mechanical properties of the alloy. Additive manufacturing (AM) technologies, specifically laser powder bed fusion, are gaining increased interest in the treatment of beta titanium alloys, due to their efficiency and their cost-cutting potential. Learn more about the chemistry and applications of this unique material below.
An excerpt:
Beta titanium alloys have an unique combination of desirable properties: their high specific strengths, creep resistance, oxidation and corrosion resistance, excellent temperature resistance up to 600°C and hardenability, make them very attractive for aerospace applications. On the other hand, the excellent biocompatibility and low elastic modulus, closer to that of human bone compared to other alloys, make Ti beta alloys an excellent material for biomedical applications.
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.
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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 market 1 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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There seems to be no limit to what heat treated titanium alloy products can do -- just listen to the name: "titans." However, its poor tribological performance means that a surface treatment is necessary in most applications.
This best of the web article shares a quick technical run-down of all you need to know about plasma/ion nitriding of titanium alloy products with guidelines and graphs to show you the way.
An excerpt:
At the moment, nitriding is the most common and rational diffusion treatment which can be used for all-over surface hardening of titanium products. Nitrided titanium has a gold/yellow color of the TiN nitride enhancing attractiveness of the treatment in many applications.
Heat treaters in the medical and aerospace sectors will eagerly tell you about titanium alloys. The hot alloy can be fantastic for intense applications once you reduce residual stresses that are developed during fabrication and increase their strength. This article is specifically about how duplex heat treatment of Ti alloys helps in relieving stress, optimizing ductility and machinability properties, and increasing strength.
An excerpt:
“Most commonly known for their excellent strength, corrosion resistance and low density, titanium alloys are a key material for important applications in the aerospace and medical industries. Duplex heat treatments of Ti alloys helps in stress relieving, optimizing ductility and machinability properties and increases strength further.”
Heat treating any aerospace projects? Then you know titanium is up there when it comes to VIP alloys in the industry. This best of the web is pulled from an aerospace magazine in which Michael Johnson of Solar Atmospheres answers five questions about creep flattening titanium:
Typical temperatures for creep flattening titanium parts
Whether of not creep flattening can only be done in a vacuum
Best fixturing for creep flattening titanium parts
Can creep flattening minimize movement
Will reheating titanium over 1,000°F affect certification
An excerpt:
"Give your heat treater your material certifications. Many mills will certify to aerospace material specification AMS 2801, AMS 4905, AMS 4911, AMS-H-81200, etc. The material often can be re-annealed while simultaneously creep flattening." - Michael Johnson, Director of Sales, Solar Atmospheres
Journey through this article by Robert Hill, FASM, president of Solar Atmospheres of Western PA, to explore the history, problems, solutions, and impacts this metal has had on multiple varied industries.
This original content piece was first released in Heat TreatToday’s Aerospace 2021 Issue. Click here to access the digital edition and all previous print/digital editions.
Robert Hill, FASM President Solar Atmospheres of Western PA
In 1987, Michael Suisman, president of Suisman & Blumenthal, sounded a stern warning that a “titanium disease” was spreading throughout the land. His clinical description was as follows:
Symptoms: The patient is completely overcome by the metal titanium. He or she tends to eat and sleep titanium, pushing all other metals out of his or her system. The patient will talk for hours about the virtues of titanium, extolling its remarkable qualities. Any blemish on titanium’s image, any negative characteristic will tend to be dismissed. Titanium’s feast-or-famine existence seems to only intrigue the patient.
Earliest known causes: In the 1950s, a number of patients were overcome with titanium, describing it as the “wonder metal.” The side effects of the “wonder metal” syndrome took many years to disappear.
Similar disease: See infatuation.
Length of disease: Lifetime.
Cure: None known.
After working with titanium for more than two decades, I have fallen victim to the “titanium disease.” What makes this metal so unique? With a quick look at the history and distinctive properties, one can easily recognize the attraction.
History
Titanium was discovered by an English pastor named William Gregor in the 1700s. In the 1800s, small quantities of the metal were produced. Before World War II, titanium as a useful metal was only a tantalizing laboratory curiosity. At that time, titanium was only valuable as an additive to white paint in its oxide form. It took the long and expensive arms race between the United States and the Soviet Union in the 1940s to create the need to solve many of titanium’s complex problems.
Since the end of the Cold War, titanium has matured primarily as an aerospace material. However, this “wonder metal” has expanded to commercial markets such as artificial body implants, golf clubs, tennis rackets, bicycles, jewelry, heat exchangers, and battery technologies.
Titanium’s unusual metal attributes include a strength comparable to steel – but 45% lighter. It is twice as strong as aluminum–but only 60% heavier. It is both biologically and environmentally inert. It will not corrode. The metal is nonmagnetic and can hold strength at high temperatures because it has a relatively high melting point. Finally, titanium has a very low modulus of elasticity and excellent thermal conductivity properties. For thermal processors, these “spring like” properties allow titanium to be readily formed or flattened with heat and pressure.
Problems
For all of its outstanding attributes, titanium is still the problem child of the metallurgical family. It is exceedingly difficult to obtain from its ore, which commonly occurs as black sand. If you scoop up a handful of ordinary beach sand and look closely, you will likely see that some of the grains are black–this is titanium ore. In certain places in the world, especially Africa and Australia, there are vast black sand deposits. Although titanium is the ninth most abundant element on the earth, turning that handful of sand into a critical jet engine blade or body implant is a significant undertaking. The refining process is about 10,000 times less efficient than making iron, which explains why titanium is costly.
Vacuum aging of titanium aircraft forgings Source: Solar
Titanium never occurs alone in nature, and it is a highly reactive metal. Known as a transition metal, it can form bonds using electrons from more than one of its shells or energy levels. Therefore, titanium is known as the streetwalker metal. Metallurgists are aware that titanium is renowned to pick up other elements quite readily during many downstream thermal and chemical processes. These reactions are often harmful to the advantageous properties of titanium and should be avoided at all times.
Solution
Since titanium has a tremendous affinity to pick up other elements at elevated temperatures, primarily oxygen and hydrogen, the only way to heat treat titanium successfully is to utilize high vacuum atmospheres. High vacuum levels of x10-5 Torr minimum and low leak rates of five microns per hour maximum are the parameters needed to retain this metal’s desired properties. An oxygen-rich atmosphere results in a hard “alpha case” surface condition. A hydrogen atmosphere results in a hydride condition, which makes titanium very brittle to the core. Both conditions can be extremely detrimental to any critical titanium component.
With high pumping capability and tight pyrometric controls, vacuum furnaces successfully provide various treatments on the “wonder metal” while avoiding the “streetwalker” syndrome. The treatments include inert stress relieving, solution treating, aging, and degassing treatments. After proper processing, bright and clean parts with low hydrogen content and zero alpha case are the norm.
The recycling of titanium is of a different magnitude than other metals due to its value. It took a shortage of titanium in the 1980s–and some innovative metallurgy–to transform valuable titanium scrap back into a qualified ingot. To do this, metallurgists used the reactivity of the metal to their advantage. Because titanium is very ductile and extremely hard to grind into powder, metallurgists learned how to use hydrogen to their advantage. Adding hydrogen to turnings and scrap makes the titanium brittle and enables the material to be pulverized into fine powders. The final product must then be thoroughly degassed or dehydrided to enter back into the revert stream, because every pound of titanium is precious.
Vacuum dehydriding (degassing) 130,000 pounds of titanium sheet and plate Source: Solar
The reactivity of titanium also assists the metallurgist to apply various surface treatments. Nitride and carbide surfaces, when used, add further protection to titanium while making the exterior harder.
Alloys
Titanium alloys are divided into four distinct types: commercially pure, alpha, beta, and alpha beta. Commercially pure grades have no alloy addition, and therefore they have very little strength. This grade of titanium is used when corrosion resistance is of greater importance. Alpha alloys are created with alpha stabilizers such as aluminum. They are easy to weld and provide a reliable strength at elevated temperatures. Beta alloys use stabilizers such as molybdenum or silicon which makes these alloys heat treatable to higher tensile strengths. Finally, the most used titanium alloy are the alpha-beta alloys. These heat treatable alloys are made with both alpha and beta stabilizers creating an excellent balance between strength, weight, and corrosion resistance.
Summary
Despite all the advances, titanium and its many alloys have not reached their apex in popularity in the world. Is there any other element that calls to mind the notion of strength quite like titanium? For what reason has this metal, named after the Titans of Greek mythology, not yet reached its full potential? If it were not for the expense, we would undoubtedly have titanium cars, houses, jets, bridges, and ships. Unfortunately, the cost of titanium keeps the “titanium disease” at bay.
About the Author: Robert Hill, FASM, president of Solar Atmospheres of Western PA, began his career with Solar Atmospheres in 1995 at the headquarters plant located in Souderton, Pennsylvania. In 2000, Mr. Hill was assigned the responsibility of starting Solar Atmospheres’ second plant, Solar Atmospheres of Western PA, in Hermitage, Pennsylvania, where he has specialized in the development of large furnace technology and titanium processing capabilities. Additionally, he was awarded the prestigious Titanium Achievement Award in 2009 by the International Titanium Association.
Roger Jones, FASM–CEO Emeritus, Solar Atmospheres (source: Solar Atmospheres)
Heat Treat Today’s Medical and Heat Treating December 2019 issue featured an article on medical alloys.Heat Treat Today asked Roger Jones, CEO Emeritus of Solar Atmospheres, Inc., to comment on how specialty medical metals are heat treated. These include titanium, niobium, tantalum, nitinol, and copper, to name a few, which in turn are used to create such standard medical devices and equipment as diagnostic guide wires, miniscule screws for implants, complex surgical tools that are operated robotically, and more. Read to see how Roger describes the hot zone and conditions under which medical device alloys are heat treated.
Vacuum furnace chambers processing titanium, niobium, chrome cobalt, and other medical device alloys are typically constructed from stainless steel. The hot zones are comprised entirely of metal (moly); graphite materials are never used in the construction of the hot zone or in fixturing parts. These furnaces process medical device alloys exclusively to avoid cross-contamination of the hot zone or the medical parts being treated.
Ultimate vacuum levels should be 1 X 10-6 Torr or better, with leak rates no greater than 2 microns Hg per hour. Gas system isolation valves aid in achieving tight vacuum, as they eliminate constant pumping on the quench system. Vacuum furnace leak up procedures are performed weekly, as well as a bake out at 2400 °F for one hour.
Horizontal, front-loading vacuum furnace with all-metal hot zone in a cleanroom setting typically used for heat treatment of medical alloys and devices (source: Solar Atmosphere)
Because of the alloys processed, cooling gases are mainly high purity argon from a liquid source. Very seldom is nitrogen used for cooling. Either type K or type N Inconel clad work thermocouples are imbedded in the loads for precise temperature readouts at +/- 10 °F or better. Processes include vacuum annealing, aging, stress relieving, solution treating, hardening, tempering, and other special processing. All furnaces are approved to the MedAccred quality standard, are surveyed to AMS 2750E, and comply with AS9100D in their processing parameters. Because the alloys are thermally treated, the vacuum furnaces operate in an air conditioned clean room with controlled temperatures and humidity levels.
Scientists from the Alliance for the Development of Additive Processing Technologies (ADAPT) at Colorado School of Mines who took part in an international research team have helped develop a nickel-titanium elastocaloric cooling shape memory alloy (SMA) that is highly efficient, eco-friendly, and easily scaled up. The alloys, in which hafnium acts as a strengthening precipitate, hold the promise of requiring only heat treatment to attain functional shape memory performance.
The international team, led by University of Maryland Professor Ichiro Takeuchi, developed the improved elastocaloric cooling material using a blend of nickel and titanium metals, fabricated by a 3D printer, that is not only potentially more efficient than current technology, but is completely “green.” Moreover, it can be quickly scaled for use in larger devices.
Dr. Aaron Stebner, Rowlinson Associate Professor of Mechanical Engineering
“The key finding of the research is that while elastocaloric materials typically used for solid-state cooling show a degradation in cooling behavior after hundreds of cycles, laser melting these metals creates fatigue-resistant nanocomposite microstructures that can cycle, with consistent cooling capacity, a million times,” said Aaron Stebner, Rowlinson Associate Professor of Mechanical Engineering and a co-author of the paper.
Professor Ichiro Takeuchi, Graduate Program Director in Materials Science and Engineering, University of Maryland
“Dr. Stebner’s expertise played a crucial role in developing understanding of the fundamental mechanism behind fatigue-resistant behavior of additively manufactured shape memory alloys. His group’s in situ synchrotron diffraction and finite element modeling capabilities gave us unique insight into the inner workings of the material,” Prof. Takeuchi said.
The work, which was published in the Nov. 29 issue of Science, is the result of a collaboration led by researchers from the University of Maryland, together with Ames Laboratory, Mines, Iowa State University, and China’s Xi’an Jiaotong University.
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.
