High-alloy metastable austenitic CrMnNi steels exhibit depending on the austenite stability a transformation induced plasticity at room temperature resulting in concurrently high strength and good ductility. The martensitic phase transformation is more pronounced as lower the austenite stability is. In addition, a steel variant with low austenite stability shows a macroscopically inhomogeneous deformation behavior during monotonic loading – the so-called Portevin Le Chatelier effect, which is commonly related to the interaction of moving dislocations and diffusing solute atoms. The serrated plastic flow is related to the formation of macroscopic bands with localized plastic deformation – so-called PLC bands, which was analyzed by in situ infrared thermography.