Journal of Powder Materials

Young-Sang Na

3 Articles

[English]
Ultra-Low-Temperature (4.2 K) Tensile Properties and Deformation Mechanism of Stainless Steel 304L Manufactured by Laser Powder Bed Fusion: Seung-Min Jeon, Young-Sang Na, Young-Kyun Kim; J Powder Mater. 2025;32(2):95-103. Published online April 30, 2025; DOI: https://doi.org/10.4150/jpm.2025.00066

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This study investigated the ultra-low-temperature (4.2 K) tensile properties and deformation mechanisms of stainless steel 304L manufactured via laser powder bed fusion (LPBF). The tensile properties of LPBF 304L were compared to those of conventional 304L to assess its suitability for cryogenic applications. The results revealed that LPBF 304L exhibited a significantly higher yield strength but lower ultimate tensile strength and elongation than conventional 304L at 4.2 K. The temperature dependence of the yield strength also favored LPBF 304L. Microstructural analysis demonstrated that LPBF 304L features a high density of dislocation cells and nano-inclusions, contributing to its greater strength. Furthermore, strain-induced martensitic transformation was observed as a key deformation mechanism at cryogenic temperatures, where austenite transformed into both hexagonal-closed packed (HCP) and body-centered cubic (BCC) martensite. Notably, BCC martensite nucleation occurred within a single HCP band. These findings provide critical insights into the mechanical behavior of LPBF 304L at cryogenic temperatures and its potential for applications in extreme environments.

Citations

Citations to this article as recorded by

Extremely low-temperature tensile behavior of 316L stainless steel additively manufactured by laser powder bed fusion
Haeum Park, Heechan Jung, Min Young Sung, Young-Kyun Kim, Jaimyun Jung, Yoona Lee, Namhyun Kang, Kyung Tae Kim, Young-Sang Na, Seok Su Sohn, Jeong Min Park
Materials Science and Engineering: A.2026; 950: 149460. CrossRef
Twinning- and transformation-induced high cryogenic strength and ductility of the CoCrFeNi high-entropy alloy: Experiment and MD simulation
Yuze Wu, Zhide Li, Charlie Kong, M.W. Fu, Hailiang Yu
International Journal of Plasticity.2026; 196: 104553. CrossRef
Microstructure, cryogenic tensile and fracture behavior of laser welded Co17.5Cr12.5Fe55Ni10Mo5 complex concentrated alloy
Jae Hyuk Lee, Jeongmin Lee, Hidemi Kato, Seungkyun Yim, Dongkyoung Lee, Gian Song, Jeong Hun Lee, Dong Jun Lee, Young-Kyun Kim, Young-Sang Na, Hyoung Seop Kim, Jongun Moon, Soo-Hyun Joo
Materials Science and Engineering: A.2026; 960: 150106. CrossRef
Origin of little post-uniform elongation of 304L/310S austenitic stainless steels at extremely low temperatures
Seon-Keun Oh, Young-Kyun Kim, Young-Sang Na
Materials Science and Engineering: A.2026; 961: 150161. CrossRef
A strong and ductile nano/micro titanium carbide reinforced metastable austenitic steel at 4.2 K
Young-Kyun Kim, Sang Hun Shim, Young-Sang Na
Journal of Materials Science & Technology.2026;[Epub] CrossRef
Understanding the unique appearance behavior of shear bands during tensile deformation of α-brass at 4.2 K
Seon-Keun Oh, Sang-Hun Shim, Young-Kyun Kim, Young-Sang Na
Materials Science and Engineering: A.2025; 945: 148989. CrossRef

[Korean]
Effect of Building Orientation on Tensile Properties of Hastelloy X alloy Manufactured by Laser Powder Bed Fusion: Seong-June Youn, GooWon Noh, Seok Su Sohn, Young-Sang Na, Young-Kyun Kim; J Powder Mater. 2025;32(2):131-137. Published online April 30, 2025; DOI: https://doi.org/10.4150/jpm.2025.00080

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Abstract PDF: In this study, the effect of build orientation on the mechanical properties of Hastelloy X fabricated by laser powder bed fusion (LPBF) process was investigated. Initial microstructural analysis revealed an equiaxed grain structure with random crystallographic orientation and annealing twins. Intragranular precipitates identified as Cr-rich M23C6 and Mo-rich M6C carbides were observed, along with a dense dislocation network and localized dislocation accumulation around the carbides. Mechanical testing showed negligible variation in yield strength with respect to build orientation; however, both ultimate tensile strength and elongation exhibited a clear increasing trend with higher build angles. Notably, the specimen built at 90° exhibited approximately 22% higher tensile strength and more than twice the elongation compared to the 0° specimen.

[English]
Ultra-Low Temperature Mechanical Response of Laser Powder Bed Fusion–Processed C-Containing CoCrFeMnNi High-Entropy Alloy: Jae-Yong Cheon, Seong-June Youn, Young-Sang Na, Young-Kyun Kim; Received April 11, 2026 Accepted May 21, 2026 Published online May 28, 2026; DOI: https://doi.org/10.4150/jpm.2026.00101

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Abstract: This study examined the microstructure and tensile behavior, from room temperature to 4.2 K, of a carbon-containing CoCrFeMnNi high-entropy alloy (HEA) fabricated by laser powder bed fusion (LPBF). Microstructural analysis revealed that the LPBF-built HEA comprised a single face-centered cubic (FCC) phase and exhibited epitaxial grain growth along the build direction. Dislocation cell structures and Cr-rich carbides were also observed within the grains. Tensile testing demonstrated a monotonic increase in both yield strength and ultimate tensile strength with decreasing temperature, and the LPBF-fabricated HEA consistently exhibited higher strength than its wrought counterpart across the entire temperature range investigated. Deformation twins were identified in all tested specimens, with the twin fraction increasing markedly at 4.2 K. These findings suggest that the excellent mechanical performance of the LPBF-fabricated carbon-containing CoCrFeMnNi HEA under ultra-low-temperature conditions is attributable to the combined effects of process-inherent microstructural features and pronounced deformation twinning.

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