Effect of High‐Temperature Deformation on Bainite Transformation of a Low‐Carbon Bainite Steel

Abstract

Unlike medium‐carbon and high‐carbon steels, the effect of the high‐temperature deformation process on the bainite transformation of low‐carbon steels is yet to be fully understood. Processes with varying high‐deformation temperatures and reductions are designed to investigate the bainitic transformation of low‐carbon steel. The results indicate that compared with the undeformed samples, for all deformation temperatures (850, 950, and 1050 °C) in the austenite temperature range, a small reduction of 5% accelerates the bainite transformation rate corresponding to the samples, and this can be attributed to the increase in the driving force. The promoting effect is increased with a decrease in deformation temperature. However, a relatively large reduction of the samples by 25% and 50% decreases the bainite transformation rate, and the inhibiting effect increases with decreasing deformation temperature. In addition, the amount of bainite increases at 1050 °C under all strains, and the amount is higher than the amount observed in undeformed samples. For the deformation temperature of 850 °C, the bainite amount increases under conditions of small reduction (5%), whereas the bainite amount decreases under large strain conditions (50% at 850 and 950 °C). The results provide a theoretical basis for optimizing the processing parameters associated with the production of low‐carbon bainite steels.