Evolution of voids close to an inclusion in hot deformation of metals

Void formation and evolution around an inclusion in an elastic-viscoplastic matrix under condition of compressive deformation have been simulated usin g finite element method. A cell model that includes matrix and inclusion wa s employed. Two kinds of loading conditions, i.e., displacement-controlled loading and stress-controlled loading, were applied to outer boundary of th e cell model. Evolution of voids goes through a sequence of shapes from con vex with two cusps, and finally to concave with three cusps together with s elf-welding lines. Along the matrix-inclusion interface three zones were pr oposed to characterize the interfacial relative motion and deformation feat ure near the interface, which are separating, sliding and sticking zones. T he large relative sliding between the inclusion and the matrix is the most distinguished feature in the compressive deformation of material with cylin drical inclusions. The size of voids is strongly affected by temperature as the strain increases. The profile of voids predicted is in good agreement with that from the existing experimental observation. (C) 2001 Elsevier Sci ence B.V. All rights reserved.