Effect Mechanism of Nitrogen Gas on Chip Formation in High Speed Cutting of Ti6Al4V Alloy Based on FEM Simulation

摘要

Titanium alloys are known for their strong chemical reactivity with surrounding gas due to their high chemical affinity, especially in dry machining. This paper describes a study of chip formation characteristics under nitrogen gas media when machining Ti6Al4V alloy with WC-Co cemented carbide cutting tools at high cutting speeds. Based on the experimental study, a finite element model of two-dimensional orthogonal cutting process for Ti6Al4V alloy at different cutting conditions was developed using a commercial finite element software Deform-2D. Saw-tooth chips with adiabatic shear bands were produced in both experiments and simulations. And the enhanced cooling and anti-frictional effects of nitrogen gas upon the high speed cutting process of Ti6Al4V alloy were analyzed. Results of this investigation indicate that the anti-frictional performance of nitrogen gas has a significant effect on chip formation when machining Ti6Al4V alloy at high cutting speeds. Compared to air, Nitrogen gas is more suitable in improving the contact conditions at chip-tool interfaces and in increasing the shear band frequency of chip formation during high speed cutting of Ti6Al4V alloy.