Deformation of metals to high strains using combination of torsion and compression

Abstract

A combined torsion and compression mode of deformation has been used to deform copper and silver to equivalent tensile true strains of ≃ 8. The microstructures have been determined by transmission electron microscopy. It has been found that at true strains within the range 4–8 there is no change in microstructure or Vickers hardness with strain. The type of microstructure is that of fine grains, similar to those formed by recrystallization. The yield stress of the fine grained structures in .copper corresponds to that predicted from the Hall- Petch relationship.