Strain-Rate Sensitivity and Energy Absorption of Hot-Rolled Sheets of DQSK, USS EX-TEN F50, and USS Dual Phase 80 Steels

The effect of strain rate ε̇ on the tensile properties of steel sheets indicate that strength increased with increasing ε̇ whereas total elongation, work-hardening exponent, and energy absorption went through minima in the ε̇ range of 0.01 to 0.20 sec^-1. Possibly sheet formability may improve with increasing e above the minima. The ε̇ hardening exponents (M values) were shown to be highest at low strains but most conveniently determined at maximum load at which the DQSK, EX-TEN F50, and Dual Phase 80 steels had M values of 0.011, 0.006, and 0,008, respectively. Post uniform elongation was found to vary directly with M value. Energy absorption by the Dual Phase 80 steel was significantly greater than that of the DQSK and EX-TEN F50 steels, suggesting that the highly formable Dual Phase 80 steel can be used advantageously in energy-management systems to increase occupant protection in automobile crashes.