Residual Stress Evolution and Mechanical State of Hard Machined Components in Sliding Contact

Precision hard turning and grinding induce very different residual stress profiles in the subsurface. The distinct patterns of residual stress profiles have significant influence on wear and fatigue performance in sliding contact. During sliding contact, the residual stress profiles and magnitudes are altered over the course of operation, which significantly affects product performance. However, evolution of machining-induced residual stresses in sliding contact has received little attention. A two-dimensional finite element simulation model of a cylinder sliding on a flat surface has been developed to study residual stress evolutions for the four typical patterns of the turned and ground residual stress profiles. The work material has been modeled as elastic-plastic with strain hardening effects. The results have shown that a residual stress component has great influence on the normal stress in that direction only. The normal strain in the residual stress direction can be slightly influenced, while the shear strain is hardly affected. The maximum residual stress relaxation occurs in the first sliding cycle, while relaxation becomes stable in subsequent sliding cycles. The patterns of residual stress profiles post sliding are similar to the "parent" ones. Residual stress relaxation at different normal loads stabilizes at about 10 μm in the subsurface. However, a smaller load may induce a larger degree of stress relaxation in the near surface. A parametric simulation study has shown that the applied load and the high friction coefficient have much greater influence on contact stresses and strains compared with the sliding speed.