Comparison of Residual Stresses in Tools Used in the Automotive Industry: Conventional vs. Innovative Heat Treatment for Cost-Effectiveness and Efficiency

Components in the automotive industry are frequently subjected to cyclic stress, which can lead to the formation of fatigue cracks. These cracks develop due to cyclic loading and can occur under low-cycle, high-cycle, or gigacycle conditions. Once the fatigue limit of a component is exceeded, crack initiation occurs, and subsequent cyclic loading causes crack propagation, ultimately resulting in fracture. Such failures can have catastrophic consequences; thus, regular inspections of transportation components are crucial. Compressive residual stresses enhance the fatigue limit of steel by impeding crack initiation. In contrast, tensile residual stresses facilitate crack initiation by creating favourable conditions for fatigue failure. The steel grade DIN EN 90MnCrV8 is widely used in producing injection moulds, tools, and gauges within the automotive industry. The research aims to identify the residual stresses induced in this steel following different heat treatment regimes. This study evaluates two distinct heat treatment approaches. The first is a conventional regime involving quenching, tempering, and a final tempering step in the coating chamber. The second is an innovative regime that combines quenching with direct tempering in the coating chamber, omitting the intermediate tempering step. The results highlight the potential of the innovative approach to achieve significant energy savings and improved cost efficiency while influencing the residual stress profile of 90MnCrV8 tool steel.