Experimental Research on Tensile Behavior of Advanced High-Strength Steel DP600 at High Strain Rate

We conducted a series of experimental investigations on the mechanical properties of DP600 dual-phase steel under strain rates from 0.001 to 3000 s⁻¹ at room temperature. A split Hopkinson tensile bar was used to capture a high strain rate response. A comparison of the quasi-static and dynamic experiment results showed that the yield strength and ultimate tensile strength increased significantly under dynamic conditions. Fractographs were analyzed by scanning electron microscopy, which indicated a better ductility at a high strain rate. Based on the experimental results, the Johnson–Cook constitutive model was applied to describe the tensile deformation behavior under various strain rates. A reasonable agreement was observed between the experimental data and the Johnson–Cook model. A metallographic analysis of tensile specimens showed that the average ferritic grain size of the fractured specimens at a high strain rate was smaller than that of the fractured specimens under quasi-static conditions. Ferritic grain refinement proved that high-speed forming could enhance the forming ability of the DP600 steel.