A dislocation pile-up model of dynamic yielding and flow in steel

Abstract

The predictions of the dynamic yield and flow behaviour of steel obtained from a dislocation pile-up model with a viscous removable obstacle were compared with results of both constant-stress and constant strain-rate tests on several steels. Very good agreement was found between the predicted and measured dynamic yield behaviour. The post-yield flow predictions exhibited trends similar to experimental results, but the quantitative agreement was less accurate. The calculated results indicate that the onset of yielding is controlled by the time history of loading, and that it depends primarily on two material parameters—the average limiting dislocation velocity ν_α, and the drag stress D. It was found that a constant critical value of plastic microstrain is reached at yield and a corresponding yield condition was formulated. The values of material parameters used in the calculations, derived by matching predicted and experimental results, are similar to those found bv other investieators.