Study Of Action Mechanism Of Fluxes And Microstructure And Properties Of Joints In ZA Alloy TIG Welding

ZA alloy is a multi-composition alloy mainly composed by Zn and Al. Due to its characteristics such as excellent mechanical property, castability, wear resisting property, low cost, this kind of alloy has gained growing commercial application. In this paper, the action mechanism of fluxes and microstructure and properties of joints in ZA alloy TIG welding are studied.The action mechanism of fluxes is studied. The results show that, fluxes cause the constriction of the arc column plasma, which cause narrow conducting channel resulting narrow welding width, and the increases of arc voltage leading to augmented weld penetration. Meanwhile losses of Zn is reduced. As the conclusion shows that, chemical reactions occur which will transit Zn by the fluxes into the welds and form liquid film protecting Zn in the welding pool from evaporation and oxidation.Slender columnar crystal, coarse tree crystal and lamellasome structure exist in welds. Columnar tree crystal and eutectic structure exist in fusion zone. HAZ is divided into two parts, annealed zone and partially annealed zone. Coarse overheating structure dose not formed.The corrosion resisting property of the welds is better than that of parent metal. The tensile strength of the joints is high than that of parent metal, and the extension percentage of the joints is slightly lower than that of parent metal. Fracture occurs on the parent metal. The tensile strength and extension percentage are slightly different between butt welded joints parent metal. but quite different between surfacing joints and parent metal. Hardness of welds and fusion zone is slightly high than that of parent metal. And the fusion zone possess the highest hardness value.