Synergistic enhancement of strength and wear resistance in nickel-based superalloy fabricated by oscillating laser directed energy deposition via laser shock peening

Inconel 718 nickel-based superalloy is widely used in aerospace and energy sectors, but traditional manufacturing methods struggle to achieve optimal synergistic performance in strength, toughness, and wear resistance. Oscillating laser directed energy deposition (OL-DED) technology significantly improves the microstructure by promoting equiaxed grain formation, yet as-deposited components still exhibit deficiencies in strength and wear resistance. This study introduces Laser Shock Peening (LSP) as a post-processing technique to further enhance mechanical properties by inducing residual compressive stresses and increasing dislocation density. This study systematically investigates the synergistic effects of the LSP process on the microstructure, residual stresses, wear mechanism, and tensile properties of OL-DED Inconel 718 superalloy. Results demonstrate that laser shock peening effectively increases the density of geometrically necessary dislocations. Residual tensile stresses in the surface layer of the OL-DED alloy are completely converted into residual compressive stresses, reaching approximately -296.5 ± 24.6 MPa. Additionally, hardness, wear resistance, and tensile strength were enhanced, with tensile strength increasing from 851.3 MPa to 898.8 MPa and yield strength rising from 547.9 MPa to 672.2 MPa. The improvement in mechanical properties can be attributed to the synergistic effects of dislocation strengthening and residual compressive stress.