High strength weldable Al-Zn-Mg base alloys produced by water atomisation

Abstract

Selected Al-Zn-Mg alloy powders, with various additions of Zr, Sc, Mn, Co, Ni, Cr, Ti, and Cu, have been produced by water atomisation. An inversely proportional dependence between the atomising water pressure and powder dispersivity has been found. The cooling rate of powders ranges from 10⁴ to 10⁶ K s^-1 depending on the size fraction. The oxide film on the powder surface is non-uniform in thickness, with coarse oxide islands, separated by a thinner oxide film. The powders were degassed and consolidated by either hot forging or hot isostatic pressing followed by extrusion. The room temperature tensile strength of alloys under T6 conditions varies between 620 and 750 MPa. The alloys show good weldability, with the strength of the welds reaching 90% of that of the base metal.