A New Strategy for Restraining Dynamic Strain Aging in GH4169 Alloy During Tensile Deformation at High Temperature

The dynamic strain aging (DSA) behavior was investigated in GH4169 alloy during tensile deforming with electric-pulse current (EPC) at 750 °C. The results show that DSA is restrained in the alloy when deformed with 40 Hz-EPC. The size of γ″ phase inner grains increases obviously and δ phase is facilitated to precipitate on grain boundary in the alloy applied with EPC, due to the promotion effect of EPC on the diffusion and segregation of atoms. Transmission electron microscopy (TEM) results indicate that dislocations can cut through small γ″ precipitate with the size of less than 10 nm, while dislocations can only bypass dislocations when γ″ precipitate grow up over 20 nm. The growth of precipitates consumes large amounts of atoms as well as the velocity of dislocation increase, which makes dislocations difficult to be pinned. Therefore, when γ″ precipitates grow up to a large size more than the critical size of dislocation pinning, DSA is significantly restrained in the alloy after necking deformed with EPC.