A published theory for 'coupled diffusional/displacive transformations' is extended to alloyed steels in order to examine the nonequilibrium growth of partially supersaturated ferrite plates as a function of the carbon concentration. The model utilises three interface response functions i.e. the diffusion-field velocity, the interface mobility and the Aziz solute trapping function to enable the estimation of the three unknown quantities: supersaturation, velocity and the composition of austenite at the interface. It is found that the theory correctly predicts the variation in the martensite-start temperature with carbon concentration, but fails to estimate the corresponding variations in the bainite-start temperatures, the reasons for which are not clear.
JOURNAL OF PHYSICS D-APPLIED PHYSICS, Vol. 34, 2001, 2573-2580.
