The Effect of Strain Rate on the Microstructure and Mechanical Properties of Q&P 980 Steel

Abstract

The effect of dynamic strain rate on the microstructure and properties of Q&P980 high-strength steel is studied. The quenching and partitioning, and tempering (Q&P-T) heat-treatment process was used to select different dynamic strain rates (1, 600, 1200 s^–1) for tensile testing. The microstructure was characterized by OM, XRD, SEM, EBSD, and other tests to investigate the relationship between microstructure and mechanical properties. The results show that the strengthening stage and the necking stage of the tested steel appear to be prolonged, at dynamic strain rates. The strength and plasticity of the tested steel were significantly improved. The microstructure and morphology of the tested steels in the deformed and undeformed areas were found to be increasingly near to each other at dynamic strain rates of 600 and 1200 s^–1. Under the impact of the TRIP effect and the adiabatic temperature rise effect at high strain rate stretching, the microstructure appears to be refined and elongated. The tested steel performed best overall at a dynamic strain rate of 1200 s^–1, with a tensile strength of 1080 MPa and an energy absorption strength of 38.97 GPa%.