Carbon content effect on high-strain-rate tensile properties for carbon steels

For the improvement or development of more crashworthy metallic materials, the effect of each chemical composition on stress–strain behavior under dynamic tension should be understood phenomenologically. Such knowledge is essential for alloy designers and engineers. Formerly, the present authors constructed a high-velocity tensile loading machine of a horizontal slingshot type to obtain dynamic tensile stress–strain relationships for structural materials, such as metallic alloys, plastics and composites at the strain rate of 1×103 s−1. This strain rate is of the same order of a car crash on the street. Using this apparatus and a usual material testing machine, seven structural carbon steels of C content ranging 0.14–0.54 wt% were tested at four strain rates of 1×10−3, 1×10−2, 1×10−1 and 1×103 s−1. From the stress–strain curves obtained, the effect of the strain rate and C content on mechanical properties for the steels were evaluated. Especially, even at the high strain rate, the yield stress and ultimate strength of the steels could be predicted by an empirical equation for quasi-static tensile tests in consideration of C and Mn contents.