EFFECT OF GRAIN-SIZE ON TENSILE-STRESS AND DUCTILITY IN AL99.99

The effect of recrystallized grain size on the tensile stress and duct ility of 99.99% purity aluminium was investigated at room temperature. It was proved that the grain size dependence of flow stress follows a modified Hall-Fetch equation with coefficients depending linearly on epsilon(1/2) UP to the stability limit. The uniform strain can also be described by a linear dependence on d(-1/2) according to which the un iform elongation increases with increasing grain size. The post-unifor m elongation changes inversely to that of the uniform one accompanied by the decrease of the strain rate sensitivity.