Adiabatic shear banding in AISI 1045 steel during high speed machining: Mechanisms of microstructural evolution

This paper presents an in-depth investigation into the formation mechanisms and microstructures of adiabatic shear bands (ASBs) in hardened AISI 1045 steel induced by high speed machining (HSM). A systematic analysis, both experimentally and theoretically, shows that a low cutting speed leads to deformed ASBs, and a high cutting speed results in transformed ASBs. The formation mechanisms of the two types of ASBs are fundamentally different. A deformed ASB is simply due to severe plastic shear, but a transformed ASB involves a process of reorientation and elongation of the martensite laths in the hardened steel, and the partitioning of elongated subgrains. It was found that a dynamic rotational recrystallization is likely the origin of the equiaxed grains in the center of a transformed ASB.