Process Research On Rotating Wire-aidedactive Gas Shielded Arc Welding

The poor weld pool fluidity is the crux of problems like bad surface forming ofweld beads in underwater welding, the poor wettablity of solder in the joining ofdissimilar materials, and the coarse microstructure of weld joints.Therefore, rotatingwire—aided active gas shielded arc welding method is used to solve these problems.On the basis of the theory of viscous molecular fluid transport properties, dropletson the top of the rotating wire will get a certain amount of rotational energy, and thispart of energy will surely be transferred to weld pool with the transition of the meltingwires, thus, the fluidity of the weld pool will be improved.Based on analyses above, a wire rotating equipment is constructed which can beused to weld steel, aluminium and copper, and its speed can be adjusted from0rpm to500rpm. The surfacing and butt welding experiment are carried out to explore the rotaryinfluence to weld forming, microstructure and the mechanical property.To study the effect of wire rotating speed on welding process is the first part of theresearch.The results show that under the conditions of DCEP, the wire rotating speedhas no significant effect on the arc shape; during the process of surfacing, droplettransfer mode is spray transfer mixed with short circuiting transfer. With the wirerotating speed increasing, the frequency of short circuiting transfer increases by8.3%atmost, short-circuit and the spray transfer current reducing by6A and3A separately, butthe voltage changeslittle. Visual sensing experiments and the tungsten particle trackingexperiments have shown that the rotation of the wire could increase not only themobility of the pool but also the droplet transfer stability based on approximateentropyby25%.To study the effect of wire rotating speed on surfacing weld forming andmicrostructure is the second part of the research.The results show that with the increaseof the rotational speed of the wire, weld reinforcement increases, penetration decreasing,weld width first increasing and then decreasing, which is mainly caused by theincreased pool mobility and the decreased heat input; The increase of wire rotatingspeed could promote the GBF and FSP to AF transformation in the fusion zone of theweld；To study the effect of wire rotating speed on butt weld microstructure and properties is the last part of the research. The results show that the increase of wirerotating speed could improve the weld microstructure of uniformity, and improve theweld longitudinal tensile property by8.3%and impact performance by28.6%of theweld than that of the weld made without wire rotating under the same processparameters.