A physical behavior model including dynamic recrystallization and damage mechanisms for cutting process simulation of the titanium alloy Ti-6Al-4V

Titanium and its alloys are attractive materials due to their low density and resistance to high temperature and corrosion. However, these materials are also known for their low machinability that leads to poor surface finish and premature tool wear. When machining such materials, serrated chips are often generated. According to the literature, this is generally due to the material damage and microstructure transformation phenomena. A flow stress modeling that takes into account material damage and dynamic recrystallization (DRX) is proposed to obtain a more realistic cutting process simulation of the titanium alloy Ti-6Al-4V. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) model is used to predict the recrystallized volume fraction involved in the proposed flow stress law. The microstructure evolution influences the material damage and the JMAK DRX initiation criterion is used to introduce this effect. A 2D Lagrangian finite element (FE) formulation is adopted to simulate the orthogonal cutting process. The cutting forces and chip morphology, obtained with the proposed behavior model, are analyzed and compared to those obtained with known tangent hyperbolic (TANH) and Johnson-Cook (JC) behavior models. A good accordance between the proposed model simulations and the experimental results is noticed. The link between recrystallization, damage and chip segmentation has been deeply analyzed.