Analysis of cutting tool geometry induced machining response, surface integrity and anisotropy relation of additively manufactured 316L stainless steel

Abstract

Although the machining responses of additively manufactured (AM) materials generally differ from wrought materials due to their microstructural properties, there is no study examining the effects of varying cutting tool rake angles in the machining of AM 316L stainless steel material. The aim of this paper is to evaluate the effects of machining using varying cutting tool rake angles and cutting speeds on the cutting response in terms of cutting force, tool wear, chip morphology and surface integrity characteristics such as microstructure, micro-hardness and x-ray diffraction (XRD) analysis of powder bed fusion – laser beam (PBF-LB) 316L. The effect of the tool rake angle on the anisotropic structure of the material was revealed by examining the machining-induced affected layer from both the built and scan planes and by comparing it with the wrought material. The findings showed that PBF-LB 316L behaves more abrasively than the wrought, creating higher cutting force and tool wear due to the differences in the friction coefficient and thermal conductivity of the materials. Although the machining-induced affected layer is not the same in the built and scan planes of the PBF-LB material due to anisotropy, it is considerably higher compared to the wrought material, especially at negative rake angles. While the hardness of PBF-LB material is higher at a low cutting speed and negative rake angle, the hardening capacity of wrought material is higher at high cutting speed and negative rake angle. PBF-LB chips have repeated adiabatic shear bands and the secondary deformation zone is more evident in wrought chips.