Uniform design and optimization of active agent and technology research for A-TIG welding of 2219 aluminum alloy

Abstract

A uniform design method was used to obtain the active flux formula for direct current electrode negative polarity activated tungsten inert gas (DCEN A-TIG) welding of 2219 aluminum alloy. According to the test results of the tensile strength of welded joint, a mathematical model was established to determine the best component of each component in the active agent and the correctness of the regression equation was verified. Compared with conventional TIG welding without active agent, DCEN A-TIG welding can effectively avoid the presentation of macroscopic and microscopic weld porosity, increasing penetration and strength of the welded joint. The three surfaces in the DCEN A-TIG weld zone presented different morphologies. The upper surface of the weld zone was composed of strong directional dendrites, whereas the cross section and longitudinal section of the weld zone were mainly composed of equiaxed dendrites. Cellular crystals were also observed on the bottom of the longitudinal section. The base metal of the joint was the hardest, and the hardness in the heat-affected zone was higher than that of the weld zone. The weakest area in the welded joint was near the fusion zone. Compared with conventional TIG welding, DCEN A-TIG welding can provide advantages.