科研之友
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摘要
Porosity defect has been a serious issue in the welding of aluminum alloys. In this paper, the mechanism of porosity formation was discussed from the perspective of metallurgical physical chemistry, and two types of bubble nucleation model were set up respectively. Given the welding current has a significant influence on porosity defect, the effect of welding current on the critical nucleation radius was investigated. The results indicated that critical nucleation radiuses in two models are the same, which were slightly affected by welding current. It means current plays an important role in the stage of bubble growth. Furthermore, bubble growth model was established under the assumption that the ratio of growth speed to solidification speed is constant. Morphology of porosity was obtained by analyzing the bubble radius varying with time. Finally, experiments were conducted and results showed the calculated morphological appearance agreed well with metallographic observation.
