Mathematical modelling for rolling force and microstructure evolution and microstructure controlling with heavy reduction in tandem hot strip rolling

A new mathematical model to predict rolling force and microstructure evolution in hot strip rolling has been proposed. This model is constructed by Orowan's theory, FDM analysis for temperature and incremental theory for the evolution of microstructure. It enables us to predict rolling force accurately, since the flow stress is directly calculated by dislocation density. As the time for computation is quite short, the proposed model can be used to ensure the deviation of grains in the product coils. The proposed model has been used to characterise large reduction tandem hot rolling. There is good relationship between ferrite grain size of the hot strip and dislocation density. Then one can plan the best schedule to roll ultra fine grain strip considering strain, strain rate and rolling temperature. Also, the proposed model is general so that one can predict microstructure in any rolling process to product new steel with correcting material data.