Finite element simulation study on pre-stress multi-step cutting of Ti-6Al-4V titanium alloy

The residual stress on the machined surface has a significant impact on the service life and fatigue strength of machined parts. In the former studies, it has been confirmed that both pre-stress cutting process and multi-step cutting process can significantly affect the residual stress distribution of the finishing machined surface, which gives expression to the increasing trend of compressive residual stress. In this paper, a finite element software Abaqus was used to establish a two-dimensional finite element simulation model for titanium alloy cutting. The finite element model was validated by the chip shape characteristics and cutting forces obtained by orthogonal cutting experiments. Based on the validated model, the simulations of single-step cutting, multi-step cutting, pre-stress single-step cutting, and pre-stress multi-step cutting processes were conducted. The chip shape characteristics, cutting forces, and residual stress distribution of the machined surface under four machining processing conditions were comparably investigated. The influence mechanism and coupling effect of multi-step machining and pre-stress machining on residual stress distribution on machined surface was explained. Investigation results indicate that both multi-step cutting and pre-stress cutting processes can increase the compressive residual stress, while multi-step cutting will change the position of minimum residual stress along the depth direction and increase the chip segmentation degree. Among the four cutting processing conditions, the pre-stress multi-step cutting will effectively increase compressive residual stress value to the utmost extent, which should be attributed to the coupled effect of pre-stress cutting and multi-step cutting processes.