C. Capdevila et al., Modeling of kinetics of austenite-to-allotriomorphic ferrite transformation in 0.37C-1.45Mn-0.11V microalloyed steel, MET MAT T A, 32(3A), 2001, pp. 661-669
The present article is concerned with the theoretical and experimental stud
y of the growth kinetics of allotriomorphic ferrite in medium carbon vanadi
um-titanium microalloyed steel. A theoretical model is presented in this wo
rk to calculate the evolution of austenite-to-allotriomorphic ferrite trans
formation with time at a very wide temperature range. At temperatures above
eutectoid temperature, where allotriomorphic ferrite is the only austenite
transformation product, the soft-impingement effect should be taken into a
ccount in the modeling. In that case, the Gilmour et al. analysis reliably
predicts the progress of austenite-to-allotriomorphic ferrite transformatio
n in this steel. By contrast, since pearlite acts as a carbon sink, the car
bon enrichment of austenite due to the previous ferrite formation is avoide
d, and carbon concentration in austenite far from the alpha/gamma interface
remains the same as the overall carbon content of the steel. Hence, the so
ft-impingement effect should be neglected, and allotriomorphic ferrite is c
onsidered to grow under a parabolic law. Therefore, assumption of a semi-in
finite extent austenite with constant boundary conditions is suitable for t
he kinetics of the isothermal decomposition of austenite. An excellent agre
ement (higher than 93 pet in R-2) has been obtained between the experimenta
l and predicted values of the volume fraction of ferrite in all of the rang
es of temperature studied.