Numerical analysis of subgrain formation during metal cutting and rolling based on the crystal plasticity theory

摘要

The grain refinement technology is important in improving the metallic material properties without the requirement of additional alloy elements. Previously, we developed an efficient method for producing ultrafine-grained steel strips using a combination of cutting and heat treatment. However, the effect of cutting on recrystallization was not apparent. The objective of this study is to investigate the effects of metal cutting on static recrystallization and outline its advantages in grain refinement using numerical simulations based on the crystal plasticity theory. Simulation results show that shear deformation in metal cutting activates more slip systems than plane strain compression via rolling, even when considering the same equivalent plastic strain. The geometrically necessary dislocations are assumed to accumulate in the crystal because many slip systems are activated in shear deformation and improve grain refinement via static recrystallization in the subsequent heat treatment. This result indicates that the deformation type plays an important role in the recrystallization process. Thus, cutting is more efficient than rolling for the production of ultrafine-grained steel.