Thermal stability of γ-alumina PVD coatings and analysis of their performance in machining of austenitic stainless steels

Stainless steels are widely used in several industrial sectors, such as engine production, medical and chemical industry. Their high strength, low thermal conductivity, high ductility and high tendency towards work hardening are the main factors for their poor machinability. In order to improve the cutting tools performance, they are often coated. γ-Al2O3 seems to be one promising candidate as coating material for machining difficult-to-machine materials. The performance, wear mechanism and thermal stability in turning, milling and drilling operations of austenitic steels with coated cemented carbide cutting tools (coating system (Ti,Al)N/γ-Al2O3) were investigated. The thermal stability was analysed with TEM/STEM.