PSI - Issue 75

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia (2025) 000 – 000

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 75 (2025) 29–34

Fatigue Design 2025 (FatDes 2025) Fatigue Analysis of Laser Powder Bed Fused 316L Stainless Steel Using Sequential Post-Treatments

John Hock Lye Pang*, Yi Zhou, Ninian Sing Kok Ho School of Mechanical and Aerospace Engineering, Nanyang Technological University, 639798, Singapore

© 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper Abstract Fatigue design performance is a critical factor in the industrial application of Laser Powder Bed Fusion (LPBF) technology. The LPBF process frequently introduces surface and internal defects during fabrication, resulting in variability in the fatigue performance of as-built, near-net-shaped specimens. This study evaluates the effectiveness of two sequential post-processing methods aimed at improving the fatigue performance of 316L stainless steel specimens fabricated using LPBF: (i) Hot Isostatic Pressing (HIP) followed by surface machining, and (ii) HIP in conjunction with surface machining and subsequent shot peening. The 316L fatigue test specimens are constructed vertically, following the ASTM E466 specifications for hour-glass flat specimen design. Experimental fatigue testing demonstrates that both post-processing methods significantly enhance fatigue performance compared to the as-built condition, with shot peening further increasing fatigue life by up to 65% beyond what is achieved by HIP and surface machining alone. Surface profile analysis indicates that shot peening induces favorable surface deformation, resulting in crack initiation sites shifting from the surface to subsurface sites, thus suppressing the surface crack propagation and enhancing fatigue life. The findings indicate that improving the fatigue properties of LPBF-processed metal parts should prioritize the development of effective post-processing techniques to modify the surface conditions. © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2025 organizers Keywords: Additive Manufacturing; 316l Stainless Steel; Post-Processing; Surface Condition; Fatigue Performance 1. Introduction While Laser Powder Fusion (LPBF) technology can achieve high relative density in metal parts exceeding 99%, the fatigue performance of the as-built components is still limited by surface roughness, lack-of-fusion defects, and microstructural heterogeneity [1, 2]. Post-fabrication treatments are commonly used to extend the fatigue life of metal parts fabricated through LPBF. One such treatment, Hot Isostatic Pressure (HIP), effectively reduces internal porosity

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the Fatigue Design 2025 organizers

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under the responsibility of Dr Fabien Lefebvre with at least 2 reviewers per paper 10.1016/j.prostr.2025.11.004