The effect of C fraction (C/N) on the stacking-fault energy of austenitic Fe-18Cr-10Mn steels with a fixed amount of C+N (0.6wt%) was investigated by means of neutron diffraction and transmission electron microscopy. The stacking-fault energies were evaluated by Rietveld whole-profile fitting combined with the double-Voigt size-strain analysis for neutron diffraction profiles using neutron diffraction. The measured stacking-fault energy was correlated with the change in deformation microstructure. Three-dimensional linear regression analyses yielded a relationship reflecting the contribution of both C+N and C/N:

SFE(mJ/m2) = -5.97 + 39.94(wt%C+N) + 3.81(C/N)

As the C fraction increased, the strain-induced γ→ε martensitic transformation was suppressed and deformation twinning became the primary mode of plastic deformation.

Effect of Carbon Fraction on Stacking Fault Energy of Austenitic Stainless Steels. T.H.Lee, H.Y.Ha, B.Hwang, S.J.Kim, E.Shin: Metallurgical and Materials Transactions A, 2012, 43[12], 4455-9