粉煤灰复合活性剂在A-TIG焊中增加熔深的机理研究

为实现对工业废弃物粉煤灰的剩余价值利用,尝试以粉煤灰作为主要原料制备焊接复合活性剂,并在AZ91镁合金板上进行A-TIG焊.利用焊缝的电特性实时采集、焊接温度场采集、电弧力测试等手段研究活性剂对电弧影响,通过熔池Bi粒子示踪实验探究活性剂对表面张力温度梯度影响.结果 表明:与常规TIG焊相比,粉煤灰复合活性剂可以使焊缝熔深增深1.4倍,熔宽减小,深宽比是常规TIG焊的1.43倍.粉煤灰复合活性剂中氟化物的解离和电离吸热过程、带电粒子的电子扩散和复合过程可以促进电弧收缩,使焊接电压升高,热输入量提高.而活性剂中的氧化物既可以通过对电弧的机械压缩作用强迫电弧收缩,又可以通过电离产生的氧元素实现对熔池液态金属表面张力温度梯度系数的改变,提高熔池中心热输入.A-TIG焊AZ91镁合金熔深增加是电弧收缩理论和表面张力温度梯度改变理论共同作用的结果.

Research on mechanism of fly ash composite active agent for penetration increasing of A-TIG welding

In order to realize the utilization of the residual value of industrial waste fly ash, an attempt was made to prepare a welded composite active agent using fly ash as main raw material, and A-TIG welding was performed on AZ91 magnesium alloy plate.The effects of active agents on arcs were studied by means of real-time welding of weld electrical properties, welding temperature field acquisition, and arc force testing.The influence of the active agent on the surface tension temperature gradient was investigated by molten pool Bi particle tracing experiment.Results show that compared with conventional TIG welding, the fly ash composite active agent could increase the welding penetration by 1.4 times, the melt width was reduced, and the depth to width ratio was 1.43 times that of conventional TIG welding.The dissociation and ionization endothermic process of fluoride in fly ash composite active agent, as well as the electron diffusion and compounding process of charged particles could promote arc shrinkage, increase welding voltage, and increase heat input.The oxide in the active agent could force the arc to shrink by mechanical compression, change the coefficient of the liquid metal surface tension temperature gradient via the oxygen element generated by ionization, and improve the heat input of the molten pool center.The increase in the penetration depth of A-TIG welding for AZ91 magnesium alloy was the result of the combination of arc shrinkage theory and surface tension temperature gradient change theory.