The effect of anisotropy of nickel-based single crystal alloys on the surface quality of sub-nanometer and near atomic scale cutting

Abstract

Nickel-based single crystal alloys are widely used in aerospace, national defense and other fields because of their excellent properties (excellent strength, high temperature creep resistance and corrosion resistance). At present, its machining accuracy is very high, and high machining surface quality is required. In the sub nano and near atomic scale (SN-NAS) cutting process, the crystal orientation of workpiece has an important impact on the internal dislocation nucleation and expansion and surface material removal. These changes will affect the evolution process of subsurface defects and have an important impact on the surface quality. The SN-NAS cutting models are established, and the relationship between dislocation emission and energy change is deduced. The cutting models of nickel-based single crystal alloys with different crystal orientations were established by the molecular dynamics method. It is found that dislocations are emitted along the direction perpendicular to the cutting surface. Due to the different crystal orientation of the workpiece, the dislocation slip direction presents anisotropy. The plastic deformation of the workpiece is closely related to dislocation slip and stacking fault propagation. Due to the difference in lattice arrangement, dislocation slip orientation and surface energy, the surface roughness shows strong anisotropy. The work hardening behavior is determined by the change of micro defect structure and dislocation density in the workpiece. At the same time, it is closely related to the movement of material slip system and the self-hardening and latent-hardening of dislocations. This study analyzes the formation mechanism of the subsurface deformation layer and how the change of crystal orientation affects the evolution of the subsurface deformation layer, so as to provide technical support for the development of SN-NAS cutting of nickel-based alloy.