Effect of pre-strain direction on energy storage process during tensile deformation of polycrystal

The energy storage process is characterised by the energy storage rate des/dwp as a function of plastic work wp or of plastic strain εP (es is stored energy). At the initial stage of plastic deformation the dependence of des/dwp on εP has a maximum. The present work is devoted to the experimental verification of a hypothesis that the maximum of des/dwp can be related to the internal micro-stresses caused by incompatible slip in grains of different orientation. The verification needed two groups of specimens in which the influence of internal micro-stresses on the energy storage rate is different. This requirement was achieved using specimens pre-strained in different directions. Experiments that make it possible to estimate the influence of internal micro-stresses on the rate of energy storage are presented. The obtained results confirm the hypothesis.