Material Ductile Failure-Based Finite Element Simulations of Chip Serration in Orthogonal Cutting of Titanium Alloy Ti-6Al-4V

Titanium alloy Ti-6Al-4V, an alpha-beta alloy, possesses ductile deformation behavior and offers advantageous properties, light weight but high strength, good resilience, and resistance to corrosion, becoming highly suitable for aerospace and biomedical applications. However, its machinability is still considered a limiting factor in improving productivity. This paper presents a finite element modeling methodology for orthogonal cutting titanium alloy Ti-6Al-4V by considering material constitutive modeling together with material ductile failure in combination with damage initiation and cumulative damage-based evolution to simulate not only ductile material separation from workpiece to form chips but also chip serration mechanism by applying an elastic-viscoplastic formulation. The finite element model is further verified with orthogonal cutting experiments (using both uncoated and TiAlN-coated carbide tools) by comparing simulated and acquired forces and simulated and captured chip images at high cutting speeds. The effects of cutting speed, feed, tool rake angle, and tool coating on the degree of chip serration are studied through the simulation results. The cutting temperature and strain distributions are obtained to study the chip serration mechanism under different cutting conditions. It is confirmed that the material failure, crack initiation, and damage evolution are of great significance in the chip serration in cutting titanium alloy Ti-6Al-4V.