Effect of internal stresses on the apparent stress dependence of dislocation velocities

Abstract

The effects of sinusoidal internal stresses on average dislocation velocities are examined for the power law stress dependence, v = V 1τ e m∗ ; the exponential stress dependence, v=v 2 exp (−D/ τ e ) and the hyperbolic started that when the magnitude of the internal stresses is comparable with the applied stress, the stress dependence of the velocity becomes anomalously high. It is suggested that neither the mechanism controlling dislocation motion nor the mechanisms of yielding may be decided on the basis of stress dependence unless care is taken to account for the effective stresses which act on the dislocations. Further, it is suggested that the stress dependence of plastic flow as obtained from stress relaxation and strain rate sensitivity tests can be misleading if the internal stresses are not taken into account.