Effect of the grain size on the rate of energy storage during the tensile deformation of an austenitic steel

The effect of the grain size on the energy storage process in a low carbon austenitic steel deformed in tension is studied. The energy conversion at each instant of the deformation process is characterized by the instantaneous rate of energy storage, desdew, where es is the stored energy and ew is the mechanical energy expended on the plastic deformation. It has been shown experimentally that, in the initial stage of plastic deformation in this austenitic steel, the dependence of the rate desdew on ew exhibits a maximum. The location of the maximum depends on the grain size of the material. In fine-grained samples, the maximum appears at smaller strains. After reaching a certain degree of deformation, plots of desdew vs. the strain for the samples of both groups are practically the same. These results are interpreted in terms of the microstructural evolution during deformation. It has been shown that the grain boundaries favour the formation and affect the evolution of low energy dislocation structures.