1996 Volume 36 Issue 12 Pages 1507-1515
The mean flow stresses developed during the hot strip rolling of nine grades of Nb steel have been examined. For this purpose, log data obtained from four different strip mills were converted to mean flow stress using the Sims approach .The results are analyzed and compared to the predictions of a mathematical model that takes microstructural evolution into account. The model is based on the Misaka equation, but incorporates the effects of dynamic, metadynamic, and static recrystallization, and also takes the accumulated strain and Nb content into account. Excellent agreement between measured and predicted mean flow stress values is obtained over the whole range of rolling temperatures. In addition, the predictions indicate that dynamic, followed by metadynamic, recrystallization takes place in the latter passes of the finishing rolling of some Nb grades. This generalization applies particularly to the low Si and high Mn grades, indicating that the Si and Mn concentrations and not only the Nb level, determine whether or not dynamic and metadynamic recrystallization are observed under hot strip rolling conditions.
