Effect of rolling temperature on microstructure evolution and mechanical properties of high carbon high manganese steel

The effects of rolling temperature ranging from −55 to 300 °C on dislocation density, twinning behavior and correlative tensile properties of a high carbon high manganese steel were investigated. Results showed that the twinning behavior was enhanced at −55 °C but suppressed at 300 °C. The twin thickness and spacing increase with the rolling temperature. At low rolling reduction of 10%, the dislocation multiplication rate decreased with the increase in rolling temperature. However, the dislocation multiplication rate maintained high level when rolled at high rolling reduction and high temperature. At a given rolling reduction, the samples rolled at −55 °C possessed higher work hardening rate. Especially, the strength of −55°C-rolled-20% sample was higher than that of 300°C-rolled-30% sample and was equivalent to room temperature (RT)-rolled-30% sample. Concurrently, the elongation of the −55°C-rolled-20% sample was higher than the other two. The contributions of dislocation strengthening and twin strengthening to the yield strength of high carbon high manganese steel after rolling at different conditions were calculated by the parameter model. The dislocation strengthening effect played a dominant role under various deformation conditions. Twin strengthening effect showed a temperature sensitivity in the temperature range selected in the present study. Lower rolling temperature showed greater contribution of twin strengthening, whereas the dislocation strengthening effect was insensitive to temperature.