Flow stress and constitutive model of OFHC Cu for large deformation, different temperatures and different strain rates

To explore the plastic flow behaviors of OFHC Cu, the thermomechanical response of OFHC Cu is investigated systematically under quasi-static (Instron, servohydraulic) and dynamic (the split Hopkinson bar) uniaxial compression. Strains over 80% are obtained experimentally, the temperatures are 77 K to 1 000 K, and the strain rates are 0.001 s-1 to 7 000 s-1. Results show that, dynamic strain aging occurs at the temperture of 500 K at a quasi-static strain rate of 0.001 s-1 . With the increase of the strain rates, the temperature region of dynamic strain aging gets higher, even disappears. In the region of higher strains, the flow stress of OFHC Cu is more sensitive to strain rate than to temperature. Based on the concept of dislocation kinematics and kinetics, taking into account the effect of viscous drag on the motion of dislocation, consult the results of a systematical experiment, a physically-based model is developed. This model could be used to predict the flow stress of OFHC Cu over a wide range of temperatures and strain rates. The experimental results are in good agreement with the theoretical predictions.