Tribological Performance of AlCrN and TiAlN Coatings in Aluminum Forming Process at High Temperature

Material transfer is a critical tribological issue in aluminum forming processes, particularly at high temperatures. Although applying PVD or CVD coatings on the forming tool surface could be a solution to alleviate the material transfer issue, selecting an appropriate coating with sufficient tribological performance is still a challenging task. This paper aims to evaluate the tribological performance of AlCrN and TiAlN coatings against 6082-T6 aluminum alloy under dry contact conditions at 400°C by using a process centered approach. The methodological approach implies: 1. pre-processing to assess the contact conditions to be simulated and prepare the experimental samples, 2. processing where the friction tests are performed, and 3. post-processing in which test results are analyzed in terms of coating performance. The warm and hot upsetting sliding test (WHUST) is used as a tribometer in the processing step. A scaled-down version of the existing WHUST is developed to integrate into the heating chamber of Bruker UMT TriboLab for precise control of the specimen and contactor temperatures. Numerical simulation is applied to identify the WHUST parameters in the pre-processing step to reproduce severe contact conditions from the industrial forming processes. The post-processing step includes the identification of Coulomb’s coefficient of friction (COF) and the surface analysis with quantitative and qualitative techniques.