Effect of pre-deformation degree on tensile properties of high carbon high manganese steel at different strain rates

The effect of cold rolling on microstructure evolution and correlative tensile properties at different strain rates of a high carbon high manganese steel were studied. Results showed that the dominant hardening mechanisms of the high carbon high manganese steel were different at varying rolling deformation stages. Below the rolling degree of 30%, the number of twins and dislocations was simultaneously increased, and the interactions between them resulted in the rapid hardening of the test steel. When the rolling degree exceeded 30%, the number of twins reached a saturation level under the selected deformation condition, while dislocation multiplication became the main hardening mechanism. In the tensile tests at different strain rates, both the strength and elongation of high carbon high manganese steel exhibited positive strain rate sensitivity (PSRS) below the rolling degree of 30%. However, only the elongation of the pre-deformed steel presented PSRS, and the tensile strength remained almost unchanged above the rolling degree of 30%. The introduced dislocations and twins during cold rolling and the evolution of these microstructures during tensile deformation were responsible for these features.