PSI - Issue 75

John Hock Lye Pang et al. / Procedia Structural Integrity 75 (2025) 29–34 Author name / Structural Integrity Procedia (2025)

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Figure 1 (a) Proposed sequential post-treatment methods; Schematics of (b) LPBF, (c) HIP, and (d) shot peening.

Figure 2 (a) Post-treated fatigue specimen geometry (unit: mm), (b) LPBF-processed as-built 316L specimens, and (c, d) fatigue specimens post-treated by Sequence 1 and Sequence 2.

2.2. Experimental Procedures The high-cycle fatigue testing on the post-treated specimens was conducted using the force-controlled sinusoidal loading with a stress ratio of R = 0.1. The tests were performed at a frequency of 50 Hz on a Shimadzu Servopulser fatigue tester under ambient conditions. Subsequently, using an optical microscope to identify and compare fatigue failure crack initiation sites. As shown in Figure 2 (c) and (d), the shot peening process resulted in visible surface deformation. Prior to conducting fatigue tests, a Keyence laser confocal microscope VK-X1000 was employed to characterize the surface profiles, aimed at studying the effect of surface deformation on fatigue performance and the mechanism of crack initiation.