Abstract: Microstructure and mechanical properties of GH4169 alloy after shot peening with different projectile diameters were studied by semi-automatic optical microscope, laser scan confocal microscope and MTS-Landmark mechanical property test machine. The apparent damage evolution of the GH4169 alloy was analyzed during uniaxial tensile process by digital image correlation method (DIC). The results show that as the projectile diameter increases from ϕ0.6 mm to ϕ4.3 mm, the surface fine-grained layer thickness of GH4169 alloy increases from 420 μm to 530 μm and its surface roughness increases by a maximum of 80.8% compared to the original specimen. After shot peening, the yield strength and tensile strength of the material are increased and its elongation decreases. The damage evolution law of the GH4169 alloy is similar before and after shot peening with the increase of plastic deformation. The material appears uniform and slow deformation in the initial stage, and begins to be damaged rapidly when the damage factor reaches the critical value. The larger the shot peening diameter is, the smaller the critical plastic strain is, and the faster the material damage occurs. The damage evolution equation of GH4169 alloy is established, which has a great significance to the life assessment of shot peening reinforced materials.

Key words: GH4169 alloy, shot peening, mechanical properties, damage evolution, digital image correlation