Distinctive features of plastic strain localization under severe plastic deformation of metals

Mechanical testing is performed and the structure of zirconium and aluminum predeformed by ~450% using multiaxial forging (MAF) and equal channel angular pressing (ECAP) is investigated. Tensile loading tests of the severely deformed specimens exhibited their tendency to necking, with the ductility of the material in the neck, however, being superior to that in the neck of initial coarse-grained specimens. The results of the experiments imply that a fundamental stage of plastic flow of solids under severe plastic deformation (SPD) is the formation of cellular-banded structure and strain localization in the fine-grain bands. This considerably retards further deformation-induced refinement of the structure by SPD, and also results in the rapid formation of a fracture neck in the materials with this structure. © 2007 Springer Science+Business Media, Inc.