Effects of multiple laser shock peening impacts on microstructure and wear performance of wire-based laser directed energy deposition 17-4PH stainless steel

As an advanced surface-strengthening technology, laser shock peening (LSP) is suitable for strengthening high-energy beam additive manufacturing components by improving the uneven temperature distribution and mechanical anisotropy problems. The present study investigated the influence of multiple LSP impacts on the microstructure evolution and wear performance of wire-based laser directed energy deposition (LDED) 17-4PH stainless steel. Results showed that with the increase of LSP impacts, the average grain size of the wire-based LDED layer decreases and the dislocation density increases. Meanwhile, the residual stress was completely converted from tensile state to compressive state, and reaches the maximum value of 424±15MPa. In addition, the significant improvement of microhardness and wear resistance after 3 LSP impacts is attributed to the combined effects of grain refinement and dislocation strengthening.