Aimed at the change in flow stress of 20CrMnTi hardened steel at high temperature and high strain rate

a separate Hopkinson pressure bar device was used to study the dynamic mechanical behavior of the specimen at 20

200

400

600 and 800 ℃. Effects of the strain

strain rate and temperature on the flow stress were analyzed

and the Johnson-Cook constitutive model of 20CrMnTi hardened steel was constructed. Experimental results show that the strain hardening effect of the material decreased with the increasing of temperature

and the strain range corresponding to the peak value of the flow stress become narrower; the material occurred dynamic strain aging in the temperature range 20-600 ℃

showed strong sensitivity to strain rate at 800℃

and it was found that the material was sensitive to temperature. The J-C constitutive model is modified by correlating the strain with the temperature softening term. The modified model can more accurately describe the dynamic mechanical behavior of 20CrMnTi hardened steel.