The effect of creep deformation on the structure of twin boundaries

Abstract

The defect structures formed in annealing twin boundaries during the high-temperature creep deformation of an austenitic stainless steel are examined. In contrast to ‘general’ high-angle grain boundaries,‘coherent’ twin boundaries retain a high proportion of extrinsic dislocations produced during dislocation-dominated creep and thus provide a good memory for previous dislocation movements in the matrix. The twin boundary defect structure can recover in a manner analogous to the formation of subgrain boundaries in the matrix and recovery can lead to twin boundary mobility.