Deformation kinetics of a TRIP steel determined by in situ high-energy synchrotron X-ray diffraction

The microstructure design and the development of predictive approaches exploiting the transformation-induced plasticity (TRIP) effect require a keen understanding of the kinetics governing the strain-induced martensitic transformation. In this work, in situ high-energy synchrotron X-ray diffraction is applied to track the deformation kinetics of a commercial AISI 301LN metastable austenitic stainless steel in real-time. The kinetics obtained, providing the behaviour of the bulk material during room temperature tension up to a true strain of 0.3, unambiguously reveals the transformation sequence of epsilon and alpha' martensite which is discussed with respect to the evolution of texture and slip. These results are enhanced with microstructure analysis including electron backscattered diffraction and transmission Kikuchi diffraction. The insights provided shed light on the role of epsilon during alpha' transformation in metastable austenitic stainless steels and show that the latter is triggered by the general activation of slip.