Synergistic evolution of microstructure and micromechanical properties induced by combined surface modifications: Emergence of surface Plateau-like strengthening zones

The demand for enhanced impact pressure in the surface strengthening of high-strength metallic materials is driven by the need for superior mechanical performance under demanding service conditions. This study investigates the synergistic evolution of the microstructure and micromechanical properties of the nickel-based superalloy GH4169 under high-energy impact composite modification, which combines the advantages of different surface strengthening techniques. The experimental setup involved mechanical shot peening and laser shock processing, with parameters including an Almen intensity of 0.25 mmA and a laser power density of 0.2 GW·mm⁻². The results indicated that the ultra-high energy input of the high-energy modification induced significant microstructural distortions, characterized by refined grain structures and the formation of a plateau-like strengthening zone with a depth of approximately 50 μm. These findings underscore the role of synergistic microstructural evolution in enhancing the material's mechanical properties and provide valuable insights into optimizing surface modification techniques for high-performance materials.