Study of microstructural stability and magnetic properties of Fe-Mn-C TRIP/TWIP steels

Abstract

In this project, two Fe-Mn-C steels (1.5% Mn and 17% Mn) will be investigated with regard to their microstructural evolution and magnetic properties. For these two steels, the so-called Transformation-Induced Plasticity (TRIP) effect is expected to occur with greater intensity for the steel containing less manganese. The main focus of this work will be on the formation of the strain-induced martensite (and its reversion). Furthermore, the formation of the martensite induced by cooling will also be investigated. The two steels will be cold rolled and then annealed at high temperatures (up to 1000°C). The samples will be characterized by Vickers microhardness testing, conventional X-ray diffraction (macrotexture), light optical microscopy (LOM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), dilatometry and ex situ and in situ magnetic measurements. From the hysteresis loops obtained at room temperature, besides the saturation magnetization (Ms), the behavior of the coercive field (Hc) of the material will be also investigated. In situ magnetization measurements will be carried out during high-temperature annealing and further cooling (up to cryogenic temperatures). In situ synchrotron X-ray diffraction measurements will be also performed at room temperature during uniaxial tensile tests to follow the corresponding phase transformations during plastic straining. (AU)