Mechanical behaviour of quenched and self-tempered reinforcing steel in tension under high strain rate

The results of an experimental research on the uniaxial tension behaviour of quenched and self-tempered reinforcing steel (grade B450C Tempcore rebar) at high strain rate are presented. Quenched and self-tempered rebar is considered to be a composite bar made of a hardened outer layer, an intermediate hardened layer and a soft inner core. The effects of the strain rate on the tensile properties of these three layers have been evaluated using results obtain from experiments at high strain rates of 250 s−1, 500 s−1 and 1000 s−1 using a split Hopkinson tension bar (SHTB). The test data in terms of dynamic increase factor (DIF) was compared with formulations proposed in literature. The purpose of this article is to quantify the effect of the strain-rate sensitiveness of the layers with different microstructures with the reference to the structural performance of a real rebar subjected to dynamic loading. Finally, the material parameters of the Johnson–Cook and Cowper–Symonds material models were determined for the three constitutive layers.