Experimental and numerical investigation of residual stresses in laser shock peened Rene-80 Ni-based superalloy

Laser shock peening (LSP) is a technique similar to shot peening that improves the mechanical properties, such as fatigue performance of metallic structures, by introducing compressive residual stresses. This study aims to present a 3D finite element simulation for simulating residual stress field after laser shock peening without absorbent coating (LSPwC) in real applications. Also, the residual stress distribution induced by LSPwC in a Rene 80 Ni-based superalloy was obtained via X-ray diffraction and hole drilling measurements. The excellent correlation between the simulated residual stress values and experimental test results proved this model reliable. Laser peening Rene-80 superalloy samples with single LSP impact at a laser power density of 6 GW/cm² led to a significant increase in the compressive residual stress (-405 MPa) compared to the unpeened sample. The yield strength of laser-peened samples was improved by ~ 16% and a reduction of ~ 12% in the failure strain compared to the baseline sample. Similarly, the laser peening increased microhardness by 26% compared to the untreated samples. Scanning electron microscopy (SEM) was also utilized to interpret the failure mechanism of samples examined before and after LSP.