Stability of residual stress induced by laser peening under cyclic mechanical loading

Sano, Yuji*; Akita, Koichi; Takeda, Kazuya*; Sumiya, Rie*; Tazawa, Toshiyuki*; Saito, Toshiyuki*; Narazaki, Chihiro*

The purpose of this paper is to investigate the behavior of compressive residual stress induced by laser peening under external loading on an age-hardened high-strength aluminum alloy A2024-T3, a low-carbon austenitic stainless steel SUS316L (Type 316L) and a nickel-based alloy NCF600 (Alloy 600). The surface residual stress was measured intermittently by X-ray diffraction during cyclic uniaxial loading. The compressive residual stress due to laser peening significantly decreased during the first few cycles at stress ratio of 0.1 with the maximum loading stress exceeding the 0.2 per cent yield stress. Under symmetric loading at the stress ratio of -1 to A2024-T3, a major decrease took place in the compression side of the first loading cycle. The surface residual stresses remained in compression within all the extent of the present experiments, even if the maximum loading stress exceeded the yield stress of the materials.