Influence of zirconium and scandium on crack susceptibility during welding of Al–Ca–Zn–Mg alloys and mechanical properties of their welded joints

Abstract

The susceptibility of experimental alloys to cracking during fusion welding was evaluated by fishbone testing and the method developed at the Bauman Moscow State Technical University (BMSTU). In terms of weldability, the experimental Al–2Ca–2.5 Mg–0.4Mn (alloy 2B) and Al–1Ca–5.5 Mg–0.5Mn (alloy 1B) alloys are comparable to commercial AMg3 and 1915 aluminum alloys, respectively. Alloying of zirconium alloy (alloy 1) led to a decrease in resistance to cracking during welding. Additional alloying of alloy 2B with scandium had a beneficial effect on its susceptibility to crack formation at an arc current of 90 A. For alloy 4, an increase in the arc current of up to 95A was accompanied by a significant increase in the crack susceptibility coefficient of up to 75%, which indicates the need to use filler wire to obtain joints from this alloy during argon arc welding. Joint alloying of the studied alloys with zirconium and scandium contributes to the destruction of axial crystallite in the weld metal (when welding without filler wire) and the overall increase in the resistance of the weld metal to crack formation during welding.