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 ca rbon austenitic steel deformed in tension is studied. The energy conve rsion at each instant of the deformation process is characterized by t he instantaneous rate of energy storage, de(s)/de(w), where e(s) is th e stored energy and e(w) is the mechanical energy expended on the plas tic deformation. It has been shown experimentally that, in the initial stage of plastic deformation in this austenitic steel, the dependence of the rate de(s)/de(w) on e(w) exhibits a maximum. The location of t he maximum depends on the grain size of the material. In fine-grained samples, the maximum appears at smaller strains. After reaching a cert ain degree of deformation, plots of de(s)/de(w) vs. the strain for the samples of both groups are practically the same. These results are in terpreted 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.