Structural parameters of the martensite transformation for austenitic steels

The effects of stacking-fault energy and strength on phase transformations in cryogenic austenitic steels are considered. An expression, which relates the transformation critical resolved shear stress, the stacking-fault energy and the strength of austenite, which is deduced to be τCi=Ai·(γSF/b)+Bi·σ0.2γ. In addition, the structural parameter, S, for the phase transformation of austenite, γSF/(σ0.2γ·b), has a great effect on the characteristics of the phase transformation. By testing and verifying, when S>0.65, γ→α, and when S<0.4, γ→ε, and when S=0.35–0.65 and γ→α+ε, respectively. Only if (C+N)<0.1%, does γSF become a chief factor affecting the phase transformation.