Residual Stress Development and Torsion Fatigue Enhancement in Additively Manufactured AlSi10Mg via Laser Shock Peening without Coating

Additive manufacturing (AM), while offering exceptional possibilities in design freedom, has not yet achieved widespread adoption for fatigue-critical components due to susceptibility to pores, surface roughness, and tensile residual stresses. Numerous post-processing techniques such as Hot Isostatic Pressing, Heat Treatment, Laser Polishing, Shot Peening etc. are being explored to improve fatigue performance, and Laser Shock Peening (LSP) has emerged as one of the most promising methods for addressing these deficiencies in AM components. Laser Shock Peening without Coating (LSPwC) offers productivity advantages, such as eliminating the need for protective coatings and simplifying automation, yet remains underexplored, particularly for AM materials.
This study explores the importance of residual stress altered by LSPwC under fully reversed torsional cyclic loading in combination with mechanical polishing, demonstrating a potential pathway toward efficient post-processing strategies for improving fatigue life. A fatigue life improvement exceeding 500% compared to the as-built condition was observed, with results correlating well with the Fatemi-Socie critical plane model, which accounts for residual stress effects. Findings are validated by fractographic and microstructural analysis.
The exploration of LSPwC is particularly important in areas where cost reduction and automation are key drivers, highlighting potential for novel applications and hybrid processing routes.