Effect of mechanical properties measured at room and elevated temperatures on the wear resistance of cutting tools with TiAlN and AlCrN coatings

A comprehensive study of the mechanical properties of TiAlN and AlCrN coated cutting tools has been performed at room and elevated temperatures (up to 500 °C) using Micro Material's NanoTest Platform System. Micro-mechanical properties have been measured such as microhardness, elastic modulus, H/E ratio, microhardness dissipation parameter (MDP), critical load values (Lc1—first crack event; Lc2—load of dramatic coating failure) during scratch testing; a scratch crack propagation resistance parameter, CPRs=Lc1(Lc2−Lc1) as well as nano-impact fracture resistance. Cutting tool life was studied under end milling conditions of the structural AISI 1040 steel.A correlation between CPRs was found with H/E ratio and MDP values. These parameters could be used to characterize the fracture toughness of the coatings. It was shown that mechanical characteristics such as H/E ratio, MDP and CPRs as well as nano-impact fracture resistance can be used to assess the resistance to adhesive-fatigue wear that is typical for end milling conditions.It was found that the microhardness of the coating and the H/E ratio reduces with rising temperature while the MDP value grows.The data obtained during quick laboratory nanohardness, nanoscratch as well as nano-impact fatigue testing can be used to rank the coatings studied and in some cases predict the relative life of a coated tool.