关键词: 药芯焊丝, 窄间隙焊, 流体流动, 立焊, 数值模拟

Abstract: There are few studies involving the interior physical phenomenon in swing arc narrow gap fluxed-cored arc welding (FCAW) currently, which leads to a lack of deep understanding of weld formation mechanism, thus affecting the stability of welding quality. Based on FLUENT software, an adaptive numerical analysis model for swing arc narrow gap FCAW in vertical position is developed. Arc heat input is modeled as a double elliptic plane heat source, which considered the effects of swing arc, arc moving direction and geometrical feature of welded joint. The filling of metal and slag is regarded as the process of liquid metal and melting slag flowing into the weld pool and it is assumed that they have the same flowing velocity. The time pulse function is applied to the flowing velocity of melting metal and slag to consider the transfer frequency. Besides, the influence of bent angle of conductive rod is also taken into account. Using FLUENT software, weld pool dynamic behavior in swing arc narrow gap vertical FACW is simulated. The results show that the built model can describe the dynamic feature of melting metal and slag in swing arc narrow gas vertical FCAW and the calculated results agree well with experimental data. A vortex occurs in the middle part of weld pool longitudinal section and the slag tends to accumulate at the middle part of the groove. The upward component of arc force and slag can improve the fluid flow pattern and help to suppress the sagging of liquid metal in vertical welding.

Key words: flux-cored wire, narrow gap welding, fluid flow, vertical welding, numerical simulation