Modeling of Ti-6Al-4V machining force considering material microstructure evolution

A physics-based model to predict the force in machining Ti-6Al-4V by accounting for the material dynamic recrystallization under thermal-mechanical loading effects is developed. The behavior of grain-size evolution in the context of mixture rule volume fraction as governed by Johnson-Mehl-Avrami-Kolmogorov (JMAK) is considered. The variation of material flow stress in machining is described by a modified Johnson-Cook flow stress model proposed by considering the grain growth and material softening. The classic Oxley’s cutting mechanics theories are implemented for machining forces calculation based upon iterative stress matching. Accounting for the thermal, mechanical, and microstructure effects in machining, the forces for both orthogonal turning and 3D oblique turning are modeled. The model validation is conducted by comparing the predicted machining forces with experimental measurements.