Effect of deformation parameters on the austenite dynamic recrystallization behavior of a eutectoid pearlite rail steel

Understandings of the effect of hot deformation parameters close to the practical production line on grain refinement are crucial for enhancing both the strength and toughness of future rail steels. In this work, the austenite dynamic recrystallization (DRX) behaviors of a eutectoid pearlite rail steel were studied using a thermo-mechanical simulator with hot deformation parameters frequently employed in rail production lines. The single-pass hot deformation results reveal that the prior austenite grain sizes (PAGSs) for samples with different deformation reductions decrease initially with an increase in deformation temperature. However, once the deformation temperature is beyond a certain threshold, the PAGSs start to increase. It can be attributed to the rise in DRX volume fraction and the increase of DRX grain with deformation temperature, respectively. Three-pass hot deformation results show that the accumulated strain generated in the first and second deformation passes can increase the extent of DRX. In the case of complete DRX, PAGS is predominantly determined by the deformation temperature of the final pass. It suggests a strategic approach during industrial production where part of the deformation reduction in low temperature range can be shifted to the medium temperature range to release rolling mill loads.