Grain Size Distributions after Single Hit Deformation of a Segregated, Commercial Nb-Containing Steel: Prediction and Experiment

The present investigation examines the applicability of the Dutta-Sellars equations in predicting the recrystallized grain sizes following deformation for a 0.046 wt pct Nb-bearing, commercially produced steel with a segregated solute content (from continuous casting). The investigation considered initial unimodal and bimodal grain size distributions before deformation that were generated by reheating the steel to 1498 K and 1423 K (1225 A degrees C and 1150 A degrees C), respectively. It was found that the reheated grain size distribution (separated into grain size classes) could be related to the solute-rich (smaller grain size classes) and solute-depleted (larger grain size classes) regions. The use of these relationships and a simple halving of the grain size within the distribution on recrystallization (used previously for homogenized samples of this steel) were found to be appropriate in the grain size class-based use of the Dutta-Sellars equations with respect to mode and maximum grain sizes after hot deformation and holding. This approach successfully predicted (confirmed by experiment) the grain size distribution after deformation in the presence of Nb segregation from continuous casting.