Effect of Carbon Fraction on Stacking Fault Energy of Austenitic Stainless Steels

The effect of C fraction (C/N) on stacking fault energy (SFE) of austenitic Fe-18Cr-10Mn steels with a fixed amount of C + N (0.6 wt pct) was investigated by means of neutron diffraction and transmission electron microscopy (TEM). The SFE were evaluated by the Rietveld whole-profile fitting combined with the double-Voigt size-strain analysis for neutron diffraction profiles using neutron diffraction. The measured SFE showed distinguishable difference and were well correlated with the change in deformation microstructure. Three-dimensional linear regression analyses yielded the relation reflecting the contribution of both C + N and C/N: SFE (mJ/m2) = –5.97 + 39.94(wt pct C + N) + 3.81(C/N). As C fraction increased, the strain-induced γ→ε martensitic transformation was suppressed, and deformation twinning became the primary mode of plastic deformation.