Temperature effect on the fracture of laser welds of aviation aluminum alloys

This paper describes an experimental study of the effect of temperature on the fracture of laser welds of Mg- and Cu-containing aviation aluminum alloys. The fracture of alloys and their welds under a uniaxial loading at temperatures of -60, 20, and 85$^\circ$C is investigated. It is revealed that the strength and ultimate strain of welds of Cu-containing alloys decrease as temperature rises because of the formation of immobile hot spots of localized plastic shifts. Heating and cooling suppress the Portevin–Le Chatelier effect and significantly reduce the ultimate strain of a Mg-containing alloy, even though such reduction is not observed in a weld. It is shown that, at a negative temperature, the maximum limiting lengthening of the weld of a Mg-containing alloy is achieved, while the formation of secondary cracks is activated during heating.