Hastelloy X is a nickel alloy that is categorized as weldable, yet tends to crack during additive manufacturing. In addition to nickel, the material also contains chromium, molybdenum and iron, and it has been theorized that the specific concentrations of each metal may have something to do with its tendency to crack. The additive manufacturing industry has been focusing on formulating a crack-free version of Hastelloy X, and in a new paper entitled “Fabrication of Crack-Free Nickel-Based Superalloy Considered Non-Weldable During Laser Powder Bed Fusion,” a group of researchers successfully processed the alloy via additive manufacturing without cracking. Furthermore they did this without having to change the material itself.
“The powder particles were spherical in morphology, having a particle size distribution D10 = 19 µm, D50 = 41 µm, and D90 = 62 µm,” the researchers state. “Cubic samples of 1 cm3 were produced under Ar atmosphere and analyzed in the as-built and annealed condition.”
Cross-sections of samples were prepared for microstructure evaluation using traditional metallography techniques, and the samples were evaluated using electroetching, a light optical microscope, and scanning electron microscopes. Heat treatment was carried out for one hour followed by water quenching.
The testing showed that the material maintained a crack-free microstructure.
“Columnar grains parallel to the building directions were evidenced through EBSD in the as-built condition,” the researchers explain. “Likewise, a typical microstructure for LPBF Ni-based superalloys was found, with smaller columnar structure size than reported elsewhere in literature. The presence of Mo-enriched carbides (~50 nm) was confirmed through EDS line scans obtained using an FE-SEM; these Mo-enriched carbides are presumed to play an important role in the cracking mechanism of this alloy.”
Hastelloy X is a desirable material for a number of reasons. It possesses a high resistance to oxidation as well as high-temperature strength. While it may be prone to cracking during additive manufacturing, it is a remarkably resistant to stress-corrosion cracking when used in petrochemical applications. It also exhibits good ductility after prolonged exposure to high temperatures.
Because of its high heat and oxidation resistance, Hastelloy X is frequently used in industrial furnace applications, as well as in gas turbine engines. Its value as a material means that it is well worth the time and work involved to develop it for additive manufacturing, particularly as additive manufacturing becomes more and more important to the aerospace industry. Curiously, materials that have shown themselves to be crack-free during welding can still form cracks during additive manufacturing, so specific formulations of these materials must be developed for additive manufacturing. This particular paper shows that crack-free Hastelloy X can be successfully additively manufactured, which is promising for many applications in the future.
Authors of the paper include Oscar Sanchez-Mata, Xianglong Wang, Jose Alberto Muñiz-Lerma, Mohammad Attarian Shandiz, Raynald Gauvin and Mathieu Brochu.
Discuss this and other 3D printing topics at 3DPrintBoard.com or share your thoughts below.
You May Also Like
What is Metrology?
3D Metrology What is 3D metrology? Metrology is the science of measurement. It establishes a common understanding of units, crucial in linking and understanding human activities. When we apply metrology...
Interview with Mei Ogata of JTL America on Testing for 3D Printing
As we move from prototyping to production, testing is becoming more and more important. Crucial in qualifying parts and materials, but also in establishing QA or developing new materials, testing...
Fast Things 8: The Shape Game and Mrs. Incredible
Imagine the answer to life, the universe, and everything is: donut. In a world of Fast Things, 3D Printing is the logical production technology. With our technology, you can go...
3D Printing News Briefs: June 8, 2019
In this week’s 3D Printing News Briefs, we’re talking about partnerships, new software and buildings, and a neat 3D printed miniature. Together, Evolve Additive Solutions and Evonik are developing materials...
View our broad assortment of in house and third party products.