Growth of extrusions in localized cyclic plastic straining

Cyclic strain localization into persistent slip bands produces on the surface of cyclically deformed materials persistent slip markings in the form of extrusions and intrusions. The localized cyclic plastic straining in persistent slip bands leads to the production and annihilation of dislocations as well as point defects. Production, annihilation and migration of point defects, preferably vacancies, is quantitatively characterized. The effect of vacancy production and migration on the extrusion growth is treated under simplified conditions. At low temperatures when vacancies are immobile, a static extrusion is produced. At elevated temperature the diffusion equation is solved, a general expression for stabilized rate of extrusion growth is obtained and temperature dependence of the growth rate can be predicted. The predictions of the model are compared with experimental observations. (C) 2008 Elsevier B.V. All rights reserved.