Manipulation of the Stacking Fault Energy of a Medium-Mn Steel Through Temperature and Hierarchical Compositional Variation

Neutron diffraction was used to interrogate the temperature-dependent deformation response of a medium-Mn steel. Through in situ measurements of phase content, the deformation response at 298 K was found to consist of phase transformation of the gamma-austenite to epsilon- and alpha-martensite (TRIP). When strained above 423 K, twinning-induced plasticity (TWIP) became the dominant deformation behavior. At intermediate temperatures, mixed-mode deformation was observed. The various deformation responses are explained relative to the calculated temperature-dependent stacking fault energy curve. For stacking fault energies <= 15 mJ/m2, phase transformation associated with stacking fault generation was observed. When the stacking fault energy was >= 22 mJ/m2, twinning was recorded. Between these values, a mixed-mode deformation was noted with both twins and epsilon-martensite being identified; the mixed-mode response is due to the chemical and microstructural inhomogeneity of the alloy. This investigation works to clarify the effect of temperature on medium-Mn stacking fault energy and the associated deformation responses within a single alloy class.

Automated summary

Neutron diffraction was used to study the deformation response of a medium-Mn steel at different temperatures. The results showed that the steel exhibited different deformation behaviors, including phase transformation, twinning, and mixed-mode deformation, depending on the temperature. These deformation responses were explained by the temperature-dependent stacking fault energy curve, as well as the chemical and microstructural inhomogeneity of the alloy.