Modelling of Nb influence on phase transformation behaviours from austenite to ferrite in low carbon steels
journal contributionposted on 2016-07-26, 10:16 authored by Li Wang, Sally V. Parker, Andrew J. Rose, G.D. West, Rachel ThomsonRachel Thomson
In this paper, a new model has been developed to predict the phase transformation behaviours from austenite to ferrite in Nb-containing low carbon steels. The new model is based on some previous work and incorporates the effects of Nb on phase transformation behaviours, in order to make it applicable for Nb-containing steels. Dissolved Nb atoms segregated at prior austenite grain boundaries increase the critical energy for ferrite nucleation, and thus the ferrite nucleation rate is decreased. Dissolved Nb atoms also apply a solute drag effect to the moving transformation interface, and the ferrite grain growth rate is also decreased. The overall transformation kinetics is then calculated according to the classic Johnson–Mehl–Avrami–Kolmogorov (JMAK) theory. The new model predictions are quite consistent with experimental results for various steels during isothermal transformations or continuous cooling.
The authors gratefully thank Tata Steel UK Limited and Loughborough University for funding this work.
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