The relation among the stored energy, microstructure and hardening effect of SA508-III steel under different deformation conditions

Abstract

The stored energy during deformation under different strains, strain rates and deformation temperatures was investigated in this paper. Thermal simulation compression and dynamic compression tests were carried out to obtain the deformed specimens with different strains, strain rates and deformation temperatures. By means of electron backscatter diffraction (EBSD) analysis, the stored energy per volume under different deformation conditions was measured. Then, the effects of strain, deformation temperature, and strain rate on the stored energy were analyzed. The increase of strain and strain rate and the decrease of temperature are conducive to the accumulation of stored energy. The correlations between the stored energy and microstructure parameters including grain and subgrain size were determined. The results show that the grain size is inversely proportional to the stored energy, while the subgrain size is inversely proportional to the square root of the stored energy. The hardening effect during plastic deformation was well described from the side of stored energy. The stress-strain relationship and hardening rate can be accurately predicted based on the evolution of stored energy. A convenient method for the acquisition of stored energy through hardness measurement was provided based on the relationship between hardness and stored energy. The proportion of the stored energy to the plastic work and its dependence on the deformation conditions were discussed. It is concluded that the stored energy can be a comprehensive quantity to connect and analyze the macro and micro behavior in the plastic deformation.