Some Experimental Studies on the Aging of the Duralumin

Abstract

The phenomena and the theories on the aging of the duralumin have apparently been exhaustively searched, but it is open to discussion if the search have been minute enough. For example, when the hardness is measured during aging, the measured values up to the saturating value are recognized to have considerable variation, and it apears not quite possible to decide that this phenomenon depends upon the dispersion of the measured values. In this study, we investigated the aging in early stages in relation to the internal friction by measuring the damping capacity during torsional damped oscillation. We know that duralumin fluctuates very widely in internal composition and remains in the unstable state in early stages of aging in which many peaked values of the damping capacity are specially observed. As the other properties are naturally affected with some corpelation to the damping capacity by the internal changes, we can tell the curve of the change in hardness approaches the saturated value gradually not in a smooth curve but with some fluctuations.