Due to the ensuing shift toward adoption of increased levels of scrap during steel production to reduce the carbon footprint, it is essential that the effects of tramp elements entering the produced steel from the scrap are understood. In this context, effects of four major tramp elements (Ni, Cu, Cr, and Mo) on the phase transformation and the microstructure evolution of medium‐manganese steels are studied by theoretical predictions. The results indicate that Cu and Ni are beneficial, whereas Cr and Mo have mixed effects due to the formation of different equilibrium metal carbides. The Cu and Ni concentrations of 0.1–0.5 wt% marginally increase the maximum retained austenite content by 2 vol%. Cr reduces the achievable maximum amount of retained austenite more strongly (decrease by 8 vol% for 0.5 wt% Cr) than Mo (decrease by 4 vol% with 0.5 wt% Mo), and Cr gives a wider processing window for achieving a microstructure with a lower variation than Mo. Combined effects of the elements are to decrease the maximum retained austenite by 8 vol% with lowering of processing temperature by 20 °C. This work provides a guideline for the selection of the optimum processing window of medium‐manganese steels in a circular economy.</jats:p>

Steel production accounts for approximately 8% of all global CO2 emissions, with the primary steelmaking route using iron ores accounting for about 80% of those emissions, mainly due to the use of fossil-based reductants and fuel. Hydrogen-based reduction of iron oxide is an alternative for primary synthesis. However, to counteract global warming, decarbonization of the steel sector must proceed much faster than the ongoing transition kinetics in primary steelmaking. Insufficient supply of green hydrogen is a particular bottleneck. Realizing a higher fraction of secondary steelmaking thus is gaining momentum as a sustainable alternative to primary production. Steel production from scrap is well established for long products (rails, bars, wire), but there are two main challenges. First, there is not sufficient scrap available to satisfy market needs. Today, only one-third of global steel demand can be met by secondary metallurgy using scrap since many steel products have a lifetime of several decades. However, scrap availability will increase to about two-thirds of total demand by 2050 such that this sector will grow massively in the next decades. Second, scrap is often too contaminated to produce high-performance sheet steels. This is a serious obstacle because advanced products demand explicit low-tolerance specifications for safety-critical and high-strength steels, such as for electric vehicles, energy conversion and grids, high-speed trains, sustainable buildings, and infrastructure. Therefore, we review the metallurgical and microstructural challenges and opportunities for producing high-performance sheet steels via secondary synthesis. Focus is placed on the thermodynamic, kinetic, chemical, and microstructural fundamentals as well as the effects of scrap-related impurities on steel properties.