Improving coated carbide tool life through wide peening cleaning (WPC) during the wet milling of H13 tool steel

The (AlCrN–TiAlN) bi-layer PVD (physical vapor deposition) coating was post-treated by a wide peening cleaning (WPC) process at various pressures and times. The micro-mechanical and adhesion properties of the studied coatings were evaluated in terms of their effects on machining performance during the wet milling of H13 tool steel. A comprehensive characterization of the cutting-edge geometry was performed by infinite focus microscope and EDX micro-analyses. Micro-mechanical and adhesion properties of the studied coatings were analyzed by nanoindentation, a nano impact test, ramped load scratch test, a repetitive load wear test and SEM. The wear performance was found to be associated with the fatigue resistance, which was improved by micro-mechanical characteristics, such as, H³/E² ratio and yield stress. Coating adhesion deteriorated as WPC pressure increased. The data of critical load for crack initiation (L_c1) and the wear evolution at a subcritical load of 1 N demonstrated this gradual deterioration in coating adhesion. However, the tool life was improved by 35% at a pressure of 0.2 MPa due to the superior balance found between fatigue resistance and coating adhesion.