Role of Retained Austenite and Deformation Induced Martensite in 0.15C-5Mn Steel Monitored by <i>in-situ</i> Neutron Diffraction Measurement during Tensile Deformation

A Fe-0.15C-5Mn-0.5Si-0.05Nb medium Mn steel annealed at 660℃ and 685℃ both exhibited inhomogeneous deformation with Lüders extremely high work hardening rates, but different strain behavior. In-situ neutron diffraction measurements during tensile test were performed to investigate changes in the phase stresses contributed strength of constituent phases, crystal orientation austenite. The role each effect crystallographic on austenite stability discussed. Deformation induced martensite showed excellent stress approximately 1000 MPa, which is close macroscopic strength. Although less strength, stage, it continuously transformed as progressed, suggesting that mainly ductility steels through a transformation plasticity effect. Austenite all orientations deformation, there was tendency for more <311> grains parallel direction remain.