Abstract
Controlling martensitic transformation behaviors in metastable austenitic steels is key to developing high-performance materials with an optimal balance of strength and ductility. When a bending load is applied during the manufacturing process, tensile and compressive loads are applied simultaneously, which can result in a transformation behavior that differs from that observed under uniaxial tensile loading due to the distributions of stress/strain and stress triaxiality. In the present study, a multimodal approach combining high-resolution X-ray nano-tomography and X-ray diffraction (XRD) was employed to investigate the martensitic transformation behavior of transformation-induced plasticity (TRIP) steel during bending tests. The martensitic transformation of austenite grains was analyzed to evaluate the effects of the grain size, grain shape, crystal orientation, and stress distribution. The transformation behavior was influenced primarily by the stress distribution, whereas the transformation rate was scattered among individual grains due to differences in grain size and shape. These variations were attributed to the effects of local stress concentrations.
