C. Capidevila et al., Modelling of kinetics of isothermal allotriomorphic and idiomorphic ferrite formation in medium carbon vanadium-titanium microalloyed steel, ISIJ INT, 41(10), 2001, pp. 1083-1092
A theoretical model is presented in this work to calculate the evolution of
austenite-to-allotriomorphic and idiomorphic ferrite transformation as a f
unction of time in medium carbon vanadium-titanium microalloyed steel. At t
emperatures above the eutectoid temperature where allotriomorphic ferrite i
s the only austenite transformation product, the soft-impingement effect sh
ould be taken into account in the modelling. By contrast, at temperatures b
elow the eutectoid temperature, the formation of pearlite avoids the carbon
enrichment of austenite due to the previous ferrite formation, and therefo
re carbon concentration in austenite far from the alpha/gamma interface rem
ains the same as the overall carbon content of the steel. Hence, the soft-i
mpingement effect should be neglected, and allotriomorphic and idiomorphic
ferrite is considered to grow under a parabolic law. The nature, size and d
istribution of the inclusions which are responsible of the intragranular nu
cleation of idiomorphic ferrite have been considered in this study. An exce
llent agreement has been obtained between experimental and predicted values
of volume fraction of ferrite in all the studied range of temperature.