Model for Predicting the Lankford Coefficient of Industrial Sheet of Automotive Steels

Resumo

A model is proposed for predicting the Lankford coefficient of steel sheet produced for the auto industry at PAO Severstal. The set of empirical model parameters is determined using an experimental database on the mean Lankford coefficient (for 138 strips of 13 steels differing greatly in composition) and additional databases on calculated steel microstructure parameters after hot rolling, and after heat treatment of cold-rolled strips. The mean error in calculations of the Lankford coefficient using the model is 7.1%. It is found that the Lankford coefficient is determined not only by the carbon content in the solid solution before cold rolling but also by the amount of carbon deposited at the ferrite grain boundaries in the form of tertiary cementite. The additional free carbon appearing in the solution when the tertiary cementite particles dissolve on heating of the cold-rolled sheet significantly affects the recrystallization and the texture formation.