Tensile behavior of a novel high-strength and high-toughness steel at strain rates from 0.1 s-1 to 1000 s-1

This paper aims to investigate the tensile behavior of a novel high-strength and high-toughness steel at different strain rates ranging from 0.1 s(-1) to 1000 s(-1). Uniaxial tensile tests with seven different strain rates were conducted by the Zwick/Roell HTM5020 testing machine. All experimental results reveal that (i) the steel is characterized by a large and homogenous deformation with little necking and relative smooth fracture, high elongation and no yield platform in the engineering stress-strain curves; (ii) the tensile behavior of the steel is sensitive to the strain rate: the yield strength, ultimate tensile strength first decrease and then increase with the increase of strain rate, while the total elongation is just the opposite; the uniform elongation decreases non-linearly as the strain rate increases. According to the obtained strain rate effects, a modified Johnson-Cook model that couples strain and strain rate based on the corrected parameter B is proposed to describe the dynamic constitutive behavior of the steel and this model is then verified by a three-dimensional finite element analysis. All numerical results demonstrate that the modified Johnson-Cook model is better to predict the strain rate sensitivity of the steel than the Johnson-Cook model. Finally, compared with other high-strength and high-toughness steels, the steel exhibits an obvious larger energy absorption, indicating that this steel has a potential application in the impact resistance and aseismic design.