Simulation of Part Surface Residual Stress Based on Grind-hardening Process

Abstract

Abstract. Grind-hardening is a new technology for steel parts surface enhancing which uses thermal and mechanical composite effects on the parts in the grinding process. During the process, the workpiece surface generates hardened layer which improves the surface quality. As a key performance indicator of measuring the part surface quality, the residual stress of the hardened layer affects the strength, fatigue life and corrosion performance of the part directly. Therefore, the study of residual stress in hardened layer plays an important role in the effective control of hardened layer quality. First, grinding temperature field is analysed for studying the distribution characteristics of surface residual stress after grind-hardening process. Then, different grinding parameters an effect on the temperature field is studied by establishing the mathematical model and the heat transfer model of the grinding zone temperature field. Furthermore, combined with the grinding force generated in the grinding process, the thermomechanical coupling analysis with finite element method is adopted to obtain the residual stress and its distribution of the part. Also, the influence mechanism of the part residual stress formation is revealed. IntroductionGrind-hardening technology is a newly built composite processing technology. It implements hardening using grinding heat on the surface, which makes the surface temperature rising to austenitizing temperature quickly, and the then rapidly cooling to the temperature of martensitic transformation. The process improves the surface hardness and wear resistance, which achieves same performance as surface hardening treatment [1][2][3]. The new technology combines the grinding technology with heat treatment well, which comply the increasingly advocated concept of process integration and green manufacturing in the engineering. Grind-hardening effect is performed by hardened layer. The performance of hardened layer varies from different microstructure [4]. Brinksmeier and Brockhoff from Gernany [5][6] proposed the technology that grinding heat can be used to quench steel surface first in 1994. Then grind-hardening technology attracted the attention of scholars from different countries. Up to now, most researches focus on local microstructure and microhardness and hardness penetration depth of the workpieces [7][8][9].During the grind-hardening process, the combining effect of grinding force and grinding heat produce a lot of grinding force on the part surface. After grinding process, part of the grinding force remains in the surface, which formating the grinding residual stress. It has a decisive impact on part performance, dimensional stability, fatigue strength and wear resistance. For this consideration, it has some practical significance to carry out the residual stress study on part surface.