Abstract
Aging processes of Al-6%Zn-2% Mg alloy weld metals obtained under the heat input of 10, 000, 5, 400 and 3, 600J/cm were examined by means of hardness measurements. X-ray small angle scattering methods and transmission electron microscopy. Aging characteristics of the weld metals strongly depended on weld heat input; the initial aging rate was least in the medium heat input. The age hardenability decreased as weld heat input increased. These results were discussed in terms of effects of cooling rate during and after solidification on aging characteristics of the alloy rapidly solidified. Introduction of dislocations during solidification retarded the initial aging rate of the weld metal. Precipitation of equilibrium phases during cooling after solidification and solute segregations decreased the age hardenability of it.
