Force modeling of Inconel 718 laser-assisted end milling under recrystallization effects

Recrystallization effects are considered for the proposed force modeling method of Inconel 718 laser-assisted end milling. Oblique cutting forces are transferred to equivalent orthogonal cutting forces through the chip flow model. According to the classic Oxley’s contact mechanics theory, cutting and axial forces are calculated when shear stress is the same as chip flow stress. The Johnson-Cook model predicts the flow stress as a function of strain, strain rate, and temperature. And one parameter in this model has a physical meaning of initial yield stress, which varies with grain size. The Johnson-Mehl-Avrami-Kolmogorov (JMAK) model describes the dynamic recrystallization process of crystalline material and then predicts grain size through the recrystallized volume fraction. Overall, recrystallization effects are considered by applying a grain size-dependent parameter in the Johnson-Cook model. And the dynamic recrystallization process is considered to predict grain size. Five experiments are conducted through a single-beam coaxial laser-assisted milling spindle. And experimental measurements are compared with analytical predictions. Overall, the proposed model provides accurate results in Fx and Fz prediction. The maximum error is less than 20%.