The effects of Al2O3 coating on serrated chip geometry and adiabatic shear banding in orthogonal cutting of AISI 316L stainless steel

Al2O3 coatings serve as a thermal barrier during a cutting operation and lead to a different chip formation due to changes in heat sharing and friction conditions, thus affect tool life substantially. In this study, the effects of Al2O3 coating on chip formation were investigated in orthogonal cutting of AISI 316L stainless steel. For this purpose, the resulted chip morphologies after the tests performed using uncoated and Al2O3 coated cemented carbides inserts at different cutting speed (75, 150, 250m/min) and feed (0.05, 0.1, 0.2, 0.3mm/rev) values were examined. In addition, a number of 2D modelling studies on chip formation were also conducted. In numerical analyses, the cutting forces and chip morphologies were obtained and compared to experimental results to confirm the validity of the employed material model. According to the results, the increased cutting speed increases the chip segmentation frequency. At high cutting speeds (Vc≥150m/min), the Al2O3 coating leads to a reduction in the segmentation frequency. Increasing cutting speeds and Al2O3 coating also result in the significant decreases in shear bandwidth. In addition, it was found that simulation results of cutting forces and shear bandwidths are in a good agreement with experimental ones at medium and high cutting speeds. On the other hand, the good prediction of the chip geometry was achieved only under specific cutting conditions.