The altered microstructure during machining process had an inverse influence on materials behavior, machining forces and surface integrity. Thus, a constitutive model which builds the response of flow stress on microstructure evolution is gaining rising interest. Based on Johnson-Cook model, a modified constitutive model coupled with microstructure evolution incremental model for machining of Ti-6Al-4V is proposed. The competing effect of work hardening and dynamic recovery mechanism on flow stress is accentuated in the constitutive model. And a new softening term is introduced to describe material softening behavior caused by dynamic recrystallization. In addition, the modified constitutive model builds the response of flow stress on microstructure evolution by introducing the dynamic recrystallization volume fraction as an internal state variable. Considering the complex and variable loading conditions during the cutting process, the incremental formulation of the Johnson-Mehl-Avrami-Kolmogorov model is proposed to capture microstructure evolution during cutting process. Subsequently, orthogonal cutting experiments and simulations of Ti-6Al-4V have been carried out to evaluate the effectiveness of the proposed model. Simulation results show that the modified constitutive model has accurate predictions of the cutting and thrust forces and illustrates that DRX is the inducement of serrated chip formation. In addition, the modified model is able to simulate the microstructure evolution during Ti-6Al-4V cutting process, which is attractive for surface integrity research of cutting operations.

在加工过程中改变的微观结构对材料行为、加工力和表面完整性有相反的影响。因此，构建流动应力对微观结构演化响应的本构模型越来越受到关注。基于Johnson-Cook模型，提出了一种改进的本构模型与微观组织演化增量模型相结合的Ti-6Al-4V加工方法。本构模型强调了加工硬化和动态恢复机制对流动应力的竞争作用。并引入了新的软化术语来描述动态再结晶引起的材料软化行为。此外，修改后的本构模型通过引入动态再结晶体积分数作为内部状态变量来构建流动应力对微观结构演化的响应。考虑到切削过程中复杂多变的载荷条件，提出了Johnson-Mehl-Avrami-Kolmogorov模型的增量公式来捕捉切削过程中的微观结构演变。随后，对 Ti-6Al-4V 进行了正交切割实验和模拟，以评估所提出模型的有效性。仿真结果表明，改进后的本构模型对切削力和推力有准确的预测，说明DRX是锯齿状切屑形成的诱因。此外，