Aluminum nitride precipitation and texture development in batch-annealed bake-hardening steel

Abstract

A model is presented that describes the development of texture during the production process of bake-hardening steel recrystallized in a batch-annealing furnace. Proper conditions are analyzed to generate a pronounced γ-fiber texture and a “pancake microstructure” that shows superior deep drawability. The γ-fiber texture is assumed to be caused by the interaction between tertiary precipitating aluminum nitride particles and the recrystallization process during heating in the furnace. Deep drawability is presented in terms of the logarithmic γ- and α-fiber X-ray intensity ratio. The computer simulation of the coupled aluminum nitride precipitation and recrystallization kinetics is based on an iterative procedure. A comparison between simulation results and available experimental data proves the ability of the model to predict the final deep drawability, taking into account the initial aluminum and nitrogen contents, the time/temperature history during slab reheating, hot rolling and coiling, the degree of cold reduction, and the heating rate during batch annealing.