Impact of cooling rate and impurity content on the phase formation and segregation on 42CrMo4 steels

During the last years the recycling rates of metals have been increasing in order to minimize carbon emissions and environmental footprint. At the same time the use of copper is seeing a rise partly due to Green Transition which creates significant amounts of low-quality scrap. This trend is causing copper and tin contamination and accumulation in steel scrap which causes significant issues during metal forming operations such as hot shortness. Therefore, it is imperative to develop scrap tolerant steel products. This requires either differentiated alloying strategies and/ or modification of the traditional processing routes to minimize the negative impact of these impurities. To this end the first step is to evaluate their solidification behaviour under different high contamination levels and cooling rates. In this work, seven distinct compositions including pure copper as well as combined copper - tin contamination at levels higher than those typically allowed by the standards were studied in order to highlight the effect of these elements on phase transformations and precipitation topology. The microstructures of the Laboratory produced samples, after casting under slow and fast cooling rates, will be examined both via Light Optical and Scanning Electron Microscopy to perform phase identification, evaluation of the segregation profile and better understand the behaviour of these impurities. This is work in progress.