Experimental analysis of energy storage rate components during tensile deformation of polycrystals

Abstract The energy storage rate d e s /d w p ( e s is the stored energy, w p the work of plastic deformation) is a macroscopic quantity that is influenced by many microscopic mechanisms. At the initial stage of plastic deformation the dependence of d e s /d w p on the plastic strain e p has a maximum. It has been suggested that the maximum of d e s /d w p is connected with long-range stresses caused by the polycrystalline nature of the material. A polycrystalline specimen deforms plastically, non-uniformly on a micro-scale, each grain in a polycrystal deforms by a different amount depending on its orientation and the constraints imposed thereon by its neighbours. In order to verify the hypothesis, two groups of specimens were prepared in which the impact of long-range internal micro-stresses on the energy storage rate differs. This requirement was achieved using specimens pre-strained in different directions. The dependence of the energy storage rate on the plastic strain for the pre-strained specimens was experimentally found. The results obtained seem to confirm the hypothesis.

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