Simulation of grain refinement of Ti6Al4V alloy during laser-assisted cutting

Under the combined effect of heating and cutting in laser-assisted machining (LAM), the material is exposed to more complex boundary conditions compared to conventional machining (CM), which inevitably affects the evolution of the microstructure. Research on how the microstructure evolves under such complex loading conditions and its effects on performance are still insufficiently understood, so an in-depth analysis of its evolution is of great significance in revealing the mechanism of material removal in LAM and in predicting and controlling surface quality. Dynamic recrystallization (DRX) is a typical microstructure evolution process in material deformation and will eventually lead to changes in grain size. Therefore, in this study, a fully coupled simulation method of LAM and the principle of cellular automata (CA) are used to construct a sequentially coupled simulation method of finite element (FE) and CA to simulate the grain refinement process during chip formation in LAM. Based on a comparison with experimental results, the influence of the laser thermal effect on the grain refinement process is analyzed. The results show that the grain refinement in the chip during LAM is significantly different from that in CM, mainly reflected in the DRX volume fraction, DRX grain size, and average grain size (AGS). The DRX region in LAM is larger than in CM, and the DRX grain size is much larger, closely related to the laser power.