Atomic Simulation of Effect of Stress-Relief Annealing on the Regulation of Residual Stress in Nano-cutting of γ-TiAl Alloy

The gamma-TiAl alloy has become one of the most competitive lightweight and high-temperature structural materials in aerospace and automotive fields because of its excellent properties. However, its room-temperature brittleness and low ductility make it easy to introduce defects and residual stresses during processing, seriously affecting its service performance. In this paper, molecular dynamics was used to simulate nano-cutting and stress relief annealing of single crystal gamma-TiAl alloy. Then the microscopic defects and residual stress distribution of single crystal gamma-TiAl alloy after nano-cutting are analyzed. Finally, the evolution of cutting residual stress during the annealing process is discussed, and the mechanism of stress relief annealing to regulate the residual stress distribution is elaborated. The results show that the annihilation of the Shockley partial dislocations and the recovery of the lattice distortion during annealing leads to the decrease in the cutting residual stresses. The residual tensile stresses on the subsurface and machined surfaces of the workpiece are transformed into residual compressive stresses due to the pinning effect of the stationary dislocations and the hindering effect of the stacking fault. The cutting residual stresses are best regulated at an annealing temperature of 900 K.