Abstract Scope |
Steady state deformation was characterized based on the experimental results of dilute single-phase aluminum alloys. It was found that, although the characteristic properties such as flow stress and grain size remained constant with time, continuous loss of grain boundaries occurred as an essential feature at steady state. A physical model, considering the activities of grain boundary dislocations, was developed to describe the kinetics of steady state deformation. According to this model, steady state as a function of strain rate and temperature is the very turning point of grain size and strength relationship, i.e., Hall-Petch relation holds when grain size is larger than that at the steady state or inverse Hall-Petch relation takes over if grain size is smaller. The transition between the two relationships is a phenomenon depending on deformation conditions, rather than an intrinsic property as generally perceived. A general scale law deformation is established accordingly. |