Computer modeling of microstructural change and strength of low carbon steel in hot strip rolling.

Abstract

A calculation model for predicting the strength of hot rolled low carbon steel sheets from their chemical compositions and processing variables has been developed as a combination of the hot deformation model, the transformation model, and the relationship between the strength and the microstructure. To make up a comprehensive model based on the previously reported hot deformation model and transformation model, the effect of stored strain on transformation kinetics and the prediction of ferrite grain size from the transformation model are studied for inclusion in the comprehensive model. Further, the relationships between the microhardnesses and the microstructures are examined. The microhardness of each microconstituent in a mixed microstructure is found dependent on its transformation temperature. These relationships are formulated for the present model. The model has been applied to the calculation of the microstructure and the tensile strength of steels. Good agreement is obtained between the values calculated and observed, and the applicability of the model for hot strip rolling process has been confirmed.