Modeling of critical cutting speed of white layer formation in the hard-cutting process

Abstract

The white layer formed during the hard-cutting process impacts the surface quality and mechanical properties of a workpiece significantly. Obtaining the accurate critical cutting speed for white layer formation is beneficial to the quality control and parameter selection of cutting. Accordingly, combining with the finite element (FE) method, a critical cutting speed model of white layer formation was developed based on the solid phase transformation free energy theory, in which the thermal–mechanical effects were considered. To calculate the free energy change during the hard-cutting process, an austenite transformation driving force model was established. This model indicated that the cutting temperature, stress, and strain can provide the required driving force for austenite transformation in the white layer formation process. An FE model of the hard-cutting process was created to obtain the thermal and mechanical parameters. The critical cutting speed of white layer formation of AISI 52100 hardened steel was predicted in this study. The predicted result was in accordance with the experimental result. Moreover, the relationship between the critical cutting speed and cutting parameters were analyzed explicitly. We found that the critical cutting speed of white layer formation increased with the tool rake angle and decreased with the increase in cutting thickness and flank wear.