  A variety of severe plastic deformation (SPD) techniques have been developed
to process materials to high strains and impart microstructural refinement.
High pressure torsion (HPT) is one technique that imparts inhomogeneous strain
to process discs with low strain in the center and high strain at the outer
edge. In the literature, this inhomogeneity is typically ignored when
characterizing wear properties after HPT. In this work, the wear rate of pure
copper discs processed by HPT was characterized by conducting dry sliding
reciprocating wear tests at a few judicious locations on the discs. From only
two discs, the wear resistance across many ranges of strains was captured.
These measurements agreed with the literature for other SPD processes at
varying strains. Wear rates dropped and plateaued at about 25% that of the
unprocessed state when processing past equivalent strains of around 15, after
which microstructural and microhardness saturation has also been observed. Some
indication of a relationship between the direction of the imposed SPD shearing
and the sliding wear direction was also observed. The incremental
microstructure, microhardness, and wear resistance evolution past equivalent
strains of ~15 indicate that for high purity copper these properties receive no
clear benefit from higher SPD strains.
