Stacking fault tetrahedra in fatigued stainless steel

Abstract

Stacking fault tetrahedra have been found in fatigued 18-13 stainless steel. From the maximum edge length the stacking fault energy is estimated to about 8 ergs/cm 2. Two mechanisms for the nucleation of triangular Frank dislocation loops during cyclic load are discussed. One mechanism requires the diffusion of vacancies created during the fatigue test, while in the other only dislocation movements are involved. As a comparison quenched specimens were observed after different annealing treatments, and only prismatic loops were found. It is concluded that the stacking fault tetrahedra are more probably created by the dislocation mechanism than by the vacancy, mechanism.