Study on chip failure mechanism in high-speed cutting process with electronic theory

Abstract

In this paper, the microscopic mechanism of 080A15 and 30CrMnMo steel chip failure modes has been studied at the level of valence electron structure (VES) based on the empirical electron theory (EET) of solids and molecules. Studies show the bonding ability and the lattice electron density are related to the chip failure form. If the bonding ability is weak and the lattice electron density is high, the chip is more prone to ductile fracture. Conversely, the chip is more prone to adiabatic shear failure to form the serrated chip divided uniformly by adiabatic shear bands (ASBs). For 080A15 steel, the bonding force between atoms is weak, and the lattice electron density is very high. It is difficult to produce the thermal-mechanical instability. Thus, the chip was formed by ductile fracture. For 30CrMnMo steel, the total bonding ability of each structural unit of carbon and alloy elements is stronger, and the lattice electron density of each structural unit is weaker, the temperature can rise instantaneously to a very high level to form the serrated chip with the adiabatic shear failure. The results of this research provide useful insights on material design and selection in high-speed cutting by studying the specific alloy elements on the influence of chip failure mechanism at the VES level.