Work hardening during primary creep of copper

An analysis of primary creep curves in copper in the temperature range 423–573 K indicated results that were consistent with the view that hardening is due to athermal rather than thermally activated processes. It was assumed that the strain rate could be divided into a steady state component and primary creep deformation. By subtracting the steady state component, curves of primary creep rates against primary creep strains were plotted. Using a rate equation that has frequently been used to describe thermally activated glide controlled deformation, flow stresses were calculated from primary creep deformation rates. Curves of flow stress against primary creep strains were obtained. If initial strains accounting for plastic deformation during application of the steady loads were added to the strains, results could be superimposed to lie on a single curve, irrespective of creep load and temperature.