Dynamic tensile behaviour of TWIP steel under intermediate strain rate loading

The dynamic tensile behaviour of a type of twinning induced plasticity (TWIP) steel was experimentally investigated over a wide range of strain rates from 0.001 to 400s^-1, with an emphasis on the intermediate strain rates (1-400s^-1). It has been found that the TWIP steel has moderate yield stress and remarkable elongation, which was believed to be related to the twinning. The ultimate tensile strength of the TWIP steel slightly decreased at strain rates from 0.001 to 0.01s^-1 and increased from 0.01 to 400s^-1. Remarkable work hardening was observed in that the TWIP steel had a high working hardening rate of approximately 1500MPa over a true strain of 0.1-0.5. Moreover, the working hardening rate had an increasing trend with strain rate. The strain rate effect for the TWIP steel could be described by Johnson-Cook hardening model. The high specific energy absorption of the TWIP steel was related to strain rate, high strain hardening exponent and large fracture elongation.