A novel methodology of surface integrity anisotropy in ATI718 plus alloy by oblique laser shock peening

Oblique Laser Shock Peening (O-LSP) is primarily used for surface modification of complex structural components. This study investigates the influence of O-LSP process parameters on surface integrity using ATI 718 Plus Alloy as the research material. It reveals the formation mechanism of surface integrity anisotropy and develops a numerical simulation method for the O-LSP stress field. Experimental results demonstrate significant anisotropy in surface roughness, residual stress, microhardness, and microstructure. Particularly when the laser diameter is 2 mm and the incidence angle is 60°, the surface roughness and residual stress along the major axis of the laser spot are 75.6 % and 49.2 % of those along the minor axis, respectively. In contrast, when the spot diameter is 2.6 mm at a 20° incidence angle, the microhardness shows the highest anisotropy. Furthermore, high-speed camera imaging captured the blast pattern of the water film, and two-phase flow simulation was used to invert the explosion dynamics of O-LSP. The explosion simulation results indicates that the load type in O-LSP is a pressure load uniformly distributed across the laser spot area, consistent with the Fabbro theory. Based on the analysis of explosion dynamics, an O-LSP stress field simulation model was established. The simulation results reproduced the anisotropy of surface integrity with a prediction accuracy of more than 80 %. This work provides a theoretical basis and methodological reference for a deep understanding of O-LSP strengthening mechanisms and its engineering applications.