| Abstract: | The microstructure evolution has been investigated for hot rolling of advanced low carbon steels containing Nb, Ti, V and Cu. The critical processing step to develop the properties of hot rolled steels is cooling after rolling when the austenite-to-ferrite transformation as well as precipitation takes place thereby determining the final mi- crostructure. Thus, the modelling work emphasizes the kinetics of errite formation. Ferrite growth rates can adequately be described by taking into account a solute-drag- like effect of Mn and Nb. The emphasis of the model is to predict the phase transfor- mation kinetics for the industrial practice of accelerated cooling. The ferrite grain size is essentially determined at the early stages of transformation and can be correlated to the trunsformation start temperature. Pcarbides and nitrides of Nb, Ti and V is controlled by Ostwald ripening of these particles. The ageing behaviour can then be described based on the Shercliff-Ashby model for precipitation hardening. The situa- tion is more complex for Cu precipitation where the ageing response is also related to a sequence of different precipitation types. |
