The viscoplasticity theory applied to the strain rate effect of 2 1/4 Cr-1Mo steel at 6000C

The viscoplasticity theory based on overstress which was shown to reproduce the rate-dependent inelastic deformation of steels at room temperature is applied to the inelastic analysis at high temperature. The monotonic and cyclic loading tests with the strain rate changes are conducted on 2 1/4 Cr-1Mo steel at 6000C. The examination of the tensile stress-strain response suggests that the viscosity function which characterizes rate-dependency in the theory should not only depend on the overstress but also on strain, and a new viscosity control function is introduced to represent such strain dependency. This extended viscoplasticity model is shown to reproduce the inelastic stress and strain behaviour observed in the experiment. (orig./RF)