Chair for Materials Science and Engineering

Marcel Muench is a PhD candidate working on the development and microstructural optimization of novel high-strength steels. In collaboration with the research group of Prof. Tsuji at Kyoto University, he investigates advanced high strength steels (AHSS), which exhibit an outstanding combination of high strength, good ductility and formability. The overarching objective of his work is to further enhance strength and ductility.
The alloys investigated have eutectoid and near-eutectoid composition within the Fe-Mn-C system. Their exceptional property profile is achieved through a novel fine-scaled microstructure consisting of martensite and metastable austenite. The processing route starts with the formation of an entirely pearlitic microstructure. Mn is substitutionally dissolved in both ferrite and cementite, with a significantly higher solubility in cementite. As a result, a lamellar or fibrous Mn concentration profile develops, characterized by Mn enrichment in cementite and Mn depletion in ferrite. Following pearlite formation, a short time austenitization treatment is applied. Due to the slow diffusion kinetics of Mn, the lamellar or fibrous Mn distribution remains even after complete transformation to austenite. Quenching from this state leads to a microstructure composed of austenite and martensite with a morphology comparable to that of the initial pearlite. This behavior is attributed to the austenite-stabilizing effect of Mn, which significantly retards the martensitic transformation in Mn-enriched regions.