A theory for the incubation period following a stress reduction during creep

Abstract

Abstract A dislocation model is presented for the phenomena following a stress reduction during creep. It is suggested that an incubation period for the production of new mobile dislocations arises because attractive junctions on the verge of breaking just before the stress reduction are no longer so after the stress reduction. The breaking stress of the junctions must be lowered by climb movements in the surrounding network before the junctions can break and release new mobile dislocations. On the basis of these concepts, an expression is derived for the length of the incubation period. This theoretical incubation period is much shorter than the time needed to establish an equilibrium structure at the new lower stress. The dependence of dislocation line tension upon line length is taken into account; as a result of this, recovery rates are predicted to depend on stress to a power larger than three. The theoretical predictions are in agreement with experimental data from the literature.