Temperature Effect on the Fracture of Laser Welded Joints of Aviation Aluminum Alloys

This paper describes an experimental study of a temperature effect on the fracture of laser welded joints of Mg- and Cu-containing aviation aluminum alloys. The fracture of alloys and their welded joints under a uniaxial loading at temperatures of −60, 20, and 85◦C is under study. It is revealed that the strength and ultimate strain of welded joints of Cu-containing alloys decrease as temperature rises because of the formation of fixed zones of localized plastic shears. 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 welded joint. It is shown that, the maximum limiting elongation of the welded joint of a Mg-containing alloy is achieved at a negative temperature, while the formation of secondary cracks is begins during heating.