Effect of Shot Peening on Surface Damage Evolution Behavior of Cu-19Ni Alloy

Shot peening is a surface modification technology with the metal surface nano machine (SNC), which can modify the surface microstructure and extend the fatigue life of Cu-19Ni alloy. The hardness, damage evolution and mechanical properties were investigated and characterized by scanning electron microscope (SEM), laser confocal microscope (LSM) and material surface performance tester (CFT). The results showed that the surface roughness and friction coefficient of Cu-19Ni alloy decreased with the increase of shot peening duration and diameter, while the microhardness and strength increased. Moreover, with the increase in shot peening duration and diameter, SEM observation showed that the fracture dimples became smaller, meanwhile, with the increase of small cleavage planes, shear tearing ridges and the thickness of the surface nano layer, the fracture mode gradually evolved from plastic to brittle fracture. The uniaxial tensile test of shot peened Cu-19Ni alloy was carried out by MTS testing machine combined with digital image correlation technology (DIC). The evolution of Cu-19Ni surface damage was analyzed, and the evolution equations describing the damage of large deformation zone and small deformation zone were established. The effect of shot peening on the damage evolution behavior of Cu-19Ni alloy was revealed.