Investigation of Cutting Temperature during Turning Inconel 718 with (Ti,Al)N PVD Coated Cemented Carbide Tools

Physical Vapor Deposition (PVD) Ti(1−x)Al(x)N coated cemented carbide tools are commonly used to cut difficult-to-machine super alloy of Inconel 718. The Al concentration x of Ti(1−x)Al(x)N coating can affect the coating microstructure, mechanical and thermo-physical properties of Ti(1−x)Al(x)N coating, which affects the cutting temperature in the machining process. Cutting temperature has great influence on the tool life and the machined surface quality. In this study, the influences of PVD (Ti,Al)N coated cemented carbide tools on the cutting temperature were analyzed. Firstly, the microstructures of PVD Ti(0.41)Al(0.59)N and Ti(0.55)Al(0.45)N coatings were inspected. The increase of Al concentration x enhanced the crystallinity of PVD Ti(1−x)Al(x)N coatings without epitaxy growth of TiAlN crystals. Secondly, the mechanical and thermo-physical properties of PVD Ti(0.41)Al(0.59)N and Ti(0.55)Al(0.45)N coated tools were analyzed. The pinning effects of coating increased with the increasing of Al concentration x, which can decrease the friction coefficient between the PVD Ti(1−x)Al(x)N coated cemented carbide tools and the Inconel 718 material. The coating hardness and thermal conductivity of Ti(1−x)Al(x)N coatings increased with the increase of Al concentration x. Thirdly, the influences of PVD Ti(1−x)Al(x)N coated tools on the cutting temperature in turning Inconel 718 were analyzed by mathematical analysis modelling and Lagrange simulation methods. Compared with the uncoated tools, PVD Ti(0.41)Al(0.59)N coated tools decreased the heat generation as well as the tool temperature to reduce the thermal stress generated within the tools. Lastly, the influences of Ti(1−x)Al(x)N coatings on surface morphologies of the tool rake faces were analyzed. The conclusions can reveal the influences of PVD Ti(1−x)Al(x)N coatings on cutting temperature, which can provide guidance in the proper choice of Al concentration x for PVD Ti(1−x)Al(x)N coated tools in turning Inconel 718.