Enhancing the high-cycle fatigue performance of GH4169 alloy by eliminating structural stress concentration through high-energy impact composite modification

Despite the advancements of traditional surface treatments like shot peening (SP) and laser shock peening (LSP) in enhancing the fatigue life of GH4169 superalloy, these techniques remain limited, particularly under high-stress concentration conditions. This study introduces a novel high-energy impact composite modification method that integrates SP and LSP to comprehensively address the fatigue strength sensitivity to stress concentration, a persistent issue for GH4169 in high-cycle fatigue applications. For the modified specimens, the fatigue limit under high-stress concentration conditions of Kt = 3 increased from 215 MPa to 517 MPa, more than doubling. Compared to grinding, composite modification shifts fatigue crack initiation from the surface to subsurface regions, demonstrating superior fatigue resistance. The high-intensity surface modification eliminates structural stress concentration as the primary factor determining the fatigue life of the material. The concentrated stress at the carbide phase interfaces within the material, which cannot be sufficiently weakened by residual compressive stress, becomes the new weak point. The study concludes that high-energy impact composite modification offers a viable method to enhance the durability and performance of GH4169 superalloys in demanding applications.