Papers by Keyword: Mixed Gas Shielding

Abstract: The effects of oxygen in helium-argon base shielded GTAW on weld shape of weld penetration are systematically investigated by bead-on-pale welding on UNS S31803 duplex stainless steel. The results show that amount of oxygen addition to He-Ar mixed shielding can significantly change the weld shape from a wide narrow type to narrow deep one and the weld depth/width ratio can be doubled due to the change in Marangoni convection condition from an outward to an inward direction.

Abstract: Aluminum alloy has being widely used in modern automobile and aeronautic industry. However, the welding of aluminum alloy, especially high strength aluminum alloy，is difficult. Porosities are usually brought in the weld metal. In this paper, MIG welding using mixed gas shielding is carried out. The characteristic shapes of porosity in weld metal are described, the mechanism of porosity formation is analyzed, and the factors that influence the tendency of porosity formation are studied. Experiment results indicate that by the use of mixed shielding gas of 38%He+62%Ar, the number of porosity is reduced, the width of HAZ and softened zone is decreased, and the mechanical properties of welded joint is increased.