Modeling of Critical Cutting Speed of White Layer Formation in Hard-Cutting Process

White layer exists on the machined surface of the hard-cutting and affects the surface quality and mechanical properties of a workpiece. Accurate predicting the critical cutting speed of white layer formation is of great significance for controlling the surface quality and selecting appropriate cutting parameters. In this work, an austenite transformation driving force calculation model of the white layer formation was established based on phase transformation thermodynamics theory, in which the influence of cutting temperature, stress and strain on the austenite transformation driving force in the hard-cutting process was taken into account. Second, a finite element (FE) model of the hard-cutting process was built by using hardened AISI52100 steel as cutting material. Then, a prediction model of critical cutting speed of the white layer formation was developed in combination with the austenite transformation driving force model and the hard-cutting FE model. Finally, the critical cutting speeds of the white layer formation at different chip thicknesses, tool rake angles and different levels of flank wear were simulated by using the critical cutting speed prediction model.