Analysis of the influence of gap width on pore formation in welding aluminium and its alloys using a comprehensive approach

It is known that weld gaps influence pore formation when welding aluminium and its alloys. At the same time, the presence of gaps can reduce pore formation during the arc welding of these materials. Unfortunately, quantitative estimates of the influence of gap width on pore formation are still not available. In this paper, a model previously developed by authors, which is based on a comprehensive approach, is used to simulate the process of pore formation in a film on the surface of aluminium for different weld gap widths. It is shown that gas humidity sharply increases in the gap as a whole during welding, which prevents thermal decomposition of hydroxides in the oxide film and facilitates pore formation. In this case, the concentration of hydroxide decomposition products in the oxide film is inversely proportional to the gap width. It is recommended that structural welds should have gaps not only between joint parts but also between a work piece and a substrate. The designs of butt-interlocking and gasket joints providing low pore formation tendency during welding are proposed. The results of the study will be useful in the development of structural joints.

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