A model for the stability of dispersed austenite in low alloy triple-p
hase steels has been developed. The model was based on the dislocation
dissociation model for classical heterogeneous martensitic nucleation
by considering stress effects on the nucleation site potency distribu
tion. The driving force for martensitic transformation has been calcul
ated with the aid of computational thermodynamics. The model allows fo
r the effects of chemical composition of austenite, mean austenite par
ticle size, yield strength of the steel and stress state on austenite
stability. Chemical enrichment in C and Mn, as well as size refinement
of the austenite particles lead to stabilization. On the contrary, th
e increase in the yield strength of the steel and triaxiality of the s
tress state lead to destabilization. The model can be used to determin
e the microstructural characteristics of the austenite dispersion, i.e
. chemical composition and size, for optimum transformation plasticity
interactions at the particular stress state of interest and can then
be useful in the design of low-alloy triple-phase steels.