SELECTION OF SHIELDING GAS FOR MECHANIZED ARC WELDING OF DISSIMILAR STEELS.

Mechanized multilayer MIG/MAG welding by high-alloy wires is associated with the feasibility of formation of lacks of fusion and slag pieces in weld metal. Therefore, the improvement of technology, in particular the selection of shielding gas composition, is urgent. Feasibility of application of mixtures CO₂ + 3 % N₂ and CO₂ + 3 % N₂ + 0.5 % O₂ as a shielding gas in mechanized arc welding of dissimilar steels is shown. It is shown that the metal oxidation occurs mainly in the inter-dendrite regions, intensity of which is increased with increase in amount of nickel in the welding wire. Weld metal alloying with nitrogen does not change the intensity of metal oxidation process and almost has no influence on slag crust removal from the deposited metal surface. 17 Ref., 2 Tables, 3 Figures. [ABSTRACT FROM AUTHOR]