Theoretical and numerical modeling of strain-rate softening instabilities:on the velocity selection of propagating Portevin-Le Chatelier deformation bands

Uniformly propagating Portevin--Le Chatelier (PLC) plastic deformation bands are studied theoretically and numerically in terms of a model which incorporates the dynamic strain ageing kinetics during plastic deformation and the effect of long-range dislocation interactions. PLC deformation banding is traced back to a wave propagation phenomenon, and the problem of propagation velocity selection is addressed for both strain- and stress-controlled tensile tests. According to the control mode, the model reveals fundamental differences in the velocity selection mechanism, which compare favourably with numerical simulations and experimental observations.