The Improvement of Surface Properties for Laser Cladding Inconel 625 Coating with Laser Shock Peening

The laser shock peening (LSP) is an effective surface treatment method. In this study, it was applied to improve the microstructures and surface properties of the laser cladding Inconel 625 coating. After LSP, the macroscopic organizational morphology of Inconel 625 coating remained unchanged, but the significant microstructure evolution during LSP was confirmed in this work. By varying the laser energy and shock times, it was found that with increasing the laser energy and shock times, the surface deformation resulted from the LSP increased. The hardened depth can reach more than 1.5 mm, which is difficult to be realized with other surface treatment methods. In addition, the surface stress state has been significantly modified, where the unLSPed sample has a tensile stress of 317.5 MPa while the LSPed sample reached a compressive stress of at least 511.6 MPa. Furthermore, the study of the retention ability of deformation at room temperature indicated its strong stability by a minimum compressive stress reduction of 0.003% after 60 days nature aging. This study provided a certain reference for LSP treatment of Inconel 625 cladding layer.