Recrystallization behavior and texture formation of rapidly annealed cold-rolled extralow carbon steel sheets

The influence of a heating rate up to 1000°C/s on recrystallization behavior and texture formation of an extralow carbon steel sheet was investigated. To discuss the experimental results of this investigation, a mathematical model for predicting recrystallization behavior was developed. An analysis using the model shows that the heating rate influences the apparent thermal activation energy of recrystallization. At a higher heating rate, C dissolved from cementite and AlN precipitated during heating decreases and as a consequence the apparent thermal activation energy is lower. This can also be a valid explanation for the fact that recrystallization of a steel sheet coiled at low temperature is retarded. The main orientations of the recrystallization texture are weakened if the heating rate is increased. This tendency has already been observed at the initial stage of recrystallization. If the specimen is heated slowly up to the initial stage of recrystallization, the decrease in the intensity of the main orientations is reduced even though the heating rate subsequently increases. This result indicates that, concerning formation of the recrystallization texture, the heating rate mainly influences the nucleation process.