Surface integrity of carbon steel under three heat treatment states subjected to orthogonal turning process

Turning process will bring about surface modification in microstructure of strengthening layer, further leading to changes in mechanical properties. This article took cutting experiments and characterization techniques to study and analyze the surface modification of strengthening layer during the turning process, including grain size, grain misorientation angle, and kernel average misorientation. Scanning electron microscopy (SEM), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM) were used to characterize experimental samples based on the Taguchi method to study influences of cutting parameters and heat treatment states on the surface modification of strengthening layer. Additionally, a nanomechanical testing system was used to obtain microhardness of the surface. Finally, the above analysis was verified by cutting chips. It shows that a larger cutting relative evaluation coefficient is conducive to obtaining a thicker strengthening layer and finer grains, thereby obtaining excellent machined surface properties.