电子束焊接熔池周期性波动的数值模拟

为了更深入地探究电子束焊接过程中的机理问题,利用数值软件Fluent,对10mm厚的2219铝合金电子束焊接熔池进行三维瞬态模拟。分析电子束焊接进入准稳态后熔池中涡流的变化规律和产生原因,并结合电子束与匙孔壁面相互作用进行讨论。结果表明:电子束焊接进入准稳态后熔池呈周期性波动;根据液态金属流动情况可将焊接熔池分为3个区域,区域Ⅰ中的液态金属维持了熔池体积的稳定,区域Ⅱ中的涡流起到扩大熔池表面的作用,区域Ⅲ中的涡流促使匙孔坍塌;通过对电子束与匙孔壁面的耦合分析可知,电子束在匙孔壁面上并不是均匀分布的,这造成了匙孔底部具有一定的滞后性。

Numerical simulation of periodic fluctuation in electron beam welding pool

In order to further explore the mechanism during electron beam welding, electron beam welding was carried out on a 10mm 2219 aluminum alloy. A three-dimensional electron beam welding model in which volume of fluid (VOF) was combined with dynamic heat source was established using numerical software Fluent to simulate the coupling between keyhole and molten pool. The process and formation of vortex in molten pool were analyzed, the interaction between electron beam and keyhole was also identified and discussed. The results show that the molten pool is divided into three parts through the analysis of liquid metals. The liquid metal in zone Ⅰ maintains the stability of the volume of the molten pool. The surface of the molten pool is enlarged by vortex in zone Ⅱ. Vortex in zone Ⅲ plays an important role in causing the keyhole to collapse. The coupling analysis of electron beam and keyhole wall shows that the electron beam is not uniformly distributed on the keyhole wall,which results in a certain hysteresis at the bottom of keyhole.