Investigation of microstructure and mechanical properties evolution in 7050 aluminum alloy and 316L stainless steel treated by laser shock peening

• Published in: Materials characterization Vol. 182; p. 111571
• Main Authors: Jing, Yandong, Fang, Xuewei, Xi, Naiyuan, Feng, Xianlu, Huang, Ke
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2021
• Subjects: Grain refinement; Laser shock peening; Plastic deformation; Residual stress; Stacking fault energy; Stacking fault energy; Laser shock peening; Plastic deformation; Residual stress; Grain refinement
• ISSN: 1044-5803
• DOI: 10.1016/j.matchar.2021.111571

Laser shock peening (LSP) has been widely applied to enhance the mechanical properties of metallic materials by modifying their sub-surface microstructures. However, controversies still exist on whether grain refinement can be obtained after the LSP process. To investigate the effect caused by LSP in metallic materials, a 7050 aluminum alloy and 316L stainless steel, which are typically high and low stacking fault energy (SFE) materials, respectively, were selected for this study. The microstructure modified by different LSP cycles and energy densities in both materials was illustrated by Electron Backscatter Diffraction (EBSD). The result shows that no grain refinement was observed regardless of the laser cycles and energy density. The most evident change was the increase of dislocation density, and higher dislocation density was observed with the increase of LSP cycles and energy density. The hardness and residual stress measurements around the LSPed areas show that LSP can effectively introduce a plastic deformation layer ranging from 600~1300 μm. It was revealed from the tensile tests that the yield strength of both materials was improved after the LSP process with the scarification of their elongations. Moreover, a potential method to calculate the dynamic yield stress of metallic materials was put forward with the help of the LSP process. [Display omitted] •LSP was carried out on both high and low-stacking fault energy materials.•LSP increased the dislocation densities but did not induce grain refinement in the treated area.•Compressive residual stress and increased hardness were obtained at a depth ranging from 600 ~ 1300 μm.•A promising way to measure the dynamic yield stress of metallic materials is put forward.