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Straight polarity direct current method(DCSP A-TIG) was applied to join 2219 high strength aluminum alloy, and the effects of single-component(AlF3,LiF), three-component (AlF3+30%LiF+10%KF-AlF3) and four-component (AlF3+30%LiF+10%KF-AlF3+10%K2SiF6) activating flux on weld face forming, weld quality (porosity), arc shape, weld penetration, joint microstructure and mechanical properties were studied. The results show that adding activating flux helps to remove the oxide film on the weld face of the 2219 aluminum alloy, improve the weld surface forming quality; the four-component activating flux of weld face forming is the best; compared with the weld quality of variable polarity TIG welding (VPTIG), DCSP A-TIG welding method significantly reduces the porosity generation in 2219 aluminum alloy weld; AlF3 single-component activating flux obviously increases the weld penetration, which has obvious dragged arc phenomenon; DCSP A-TIG welded seam has the same structure component as the parent metal. Welding current has a greater influence on DCSP A-TIG weld microstructure, increasing current may result in the coarsening of the joint microstructure. The strength and elongation of the DCSP A-TIG welding joint, which are coated with four-component activating flux are the highest, and the mechanical properties are nearly the same as VPTIG welding. The DCSP A -TIG welding method of 2219 high strength aluminum alloy is of great value to the engineering application. |
