The influence of thermal effects on wear behaviour of TiAlN-coated cemented carbide tools during turning of AISI 1045+N

High-performance cutting tools are exposed to high temperatures during use. Understanding the thermal influence on the coating and substrate properties is therefore key to predict the tool performance of PVD-coated tools. In machining tests, thermal and mechanical loads cannot be separated from each other. To investigate the influence of thermal load separately, the tools in this study, TiAlN-coated cemented carbides, were initially only subjected to thermal load. Its influence on the coating and substrate properties was then analysed. To understand the effect on cutting behaviour, both thermally loaded and reference tools were used in machining tests and their wear behaviour was analysed. With this approach, the effect of the thermal load itself on the coating and substrate properties could be isolated. On key finding is that the residual compressive stresses in the TiAlN coating were reduced. In addition, the cobalt concentration at the interface of the substrate was reduced as well. In wear investigation these pre-tempered tools featured an average 24 % reduced tool life compared to the reference tools.