Arconik SMZ, Moscow, Russia:

A. M. Drits, Director for Business and New Technology Development, e-mail: Alexander.Drits@arconic.com

Moscow Polytechnic University, Moscow, Russia:
V. V. Ovchinnikov, Professor at the Department of Metal Science

Opytnyy zavod Avial, Moscow, Russia:
B. L. Igonkin, Director

The influence of scandium in the filler wire on the resistance to the formation of hot cracks in the argon arc welding of aluminum alloys 1420, 1565ch and 1901 is considered. It’s shown, that alloying of filler wire with scandium increases the critical strain rate in the MWTU sample and almost completely eliminates the formation of hot cracks in the “fish skeleton” sample. It’s found, that the increase of mechanical properties of welded joints while introducing scandium into the filler wire is achieved both by grinding the crystal structure of the seam, and by hardening the solid solution with scandium. The achievement of the most pronounced effect from the introduction of scandium into the welding wire is observed at its concentration of 0,15–0.25%. And in the presence of zirconium in the alloy the effect is also possible with a scandium content of 0.1% in the filler wire. When welding semi-product aluminum alloys with rough structural heterogeneity, the use of filler wires doped with scandium, ensures the production of quality welded joints with multi-pass manual welding with a magnesium content of more than 4.5% in the wire. The introduction of scandium into the filler wire for welding of aluminum alloys 1420, 1565ch и 1901 contributes to a slower reduction in the properties when performing repeated welds of defective parts of the seams compared to traditionally used wires. Besides, it can be noted, that the risk of a defect in the weld is almost completely eliminated, which practically reduces the number of repair welds used to one. Analysis of the microstructure of the weld metal showed, that the grain size in the cast structure of the seam, when using wfiller wires doped with scandium, about 2–3.5 times less, than in the case of additives without it. It’s important to note, that the use of filler wires containing magnesium at the level of 4.5% allows to rise up to 97–195 kJ/m² impact strength on the fusion zone of alloys 1420 and 1565ch in the fusion zone, where it usually has the lowest values. This result seems to have been made possible by the repartition of magnesium in the fusion zone. You need to consider, when a large content of scadium (0.44%) in the welding wire Sv1597 the ductility and toughness of the weld decrease as a result of emergence of a large number of primary selections scandium-containing fractions.

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