Whole process analysis of microstructure evolution during chip formation of high-speed machining OFHC copper

Abstract

Higher cutting speed is always the pursuit of industries as it is one of the most effective methods to improve machining efficiency, which requires a better understanding of deformation and microstructure evolution process during chip formation. In this study, chip formation process is divided into three different sections of pre-loading, loading and unloading to analyze the mechanisms of microstructure evolution sequentially through a coupled finite element and cellular automata approach. The non-uniform distributed fields of strains, strain rates and temperatures induced by different stage during chip formation process are obtained and then transferred as boundary conditions for microstructure evolution. In pre-loading condition, microstructure evolution appears only along shear band with small sizes, which provides more boundaries for activation of DRX mechanisms in following conditions. Final microstructures always show a gradient distribution along shear direction, and secondary shear zone makes the greatest contribution to grain refinement. Average grain sizes and microstructure distribution have shown a good agreement between experimental data and simulation results, which indicates that this sequential simulation approach can perform a better description of those process characteristics of microstructure evolution during a continuous process with complicated boundary conditions.