The impact of retained austenite and its stability on the mechanical properties of new generation steels has been widely investigated in recent decades. However, specific knowledge is missing on the kinetics of austenite transformation under dynamic and especially triaxial loading conditions. This project aims at discovering the mechanisms both from a viewpoint of the microstructure as well as the strain conditions that govern the austenite behavior in severe conditions like crash and toughness applications. Through a combination of detailed characterization of carefully selected microstructure distributions with in situ measurement techniques and micro-mechanical modelling a clear link will be established within a specific strain rate range. Taking into account temperature dependence mostly at quasi-static level and triaxiality influencing austenite transformation near the fracture tip new insight will grow on improving material properties under these rigorous conditions.