The Characteristics Of Laser-MIG Hybrid Welding Process With Filler Wire For Aluminum Alloy

Laser-MIG hybrid welding process makes full use of the advantages of laser and arc welding technology,has the characteristics of high speed and stability,solve effectively the problem of heat injury caused by arc welding and other problems such as bad bead appearance,high porosity ratio and crack caused by laser welding for aluminum alloy.But for the plates of middle thickness,welding speed is limited because of low deposition efficiency.A new laser-MIG hybrid welding process with additional cold wire was proposed,which may help to solve the problem so that deposition efficiency and welding efficiency can be improved without increasing heat input.In this paper,firstly it was studied that the influence of materials on weld characteristics,by using 5A06 aluminum alloy,2A14 aluminum alloy,and wires of ER5356 and ER2319.The results show that with the same experimental conditions,weld penetration depth of 5A06 aluminum alloy is significantly higher than that of 2A14,and weld penetration depth with ER5356 wire is significantly higher than that of ER2319;meanwhile,for 2A14 aluminum alloy,the penetration increases when filling some ER5356 wires,and decreases significantly with ER2319,but for 5A06 aluminum alloy,all penetrations decrease with any one of these wires.Then,compared to laser-MIG hybrid welding process for aluminum alloy,the effect of laser power,welding speed,welding current and other key parameters on bead appearance,the stabilities of penetration as well as reinforcement and deposition efficiency were systematically studied by using laser-MIG hybrid welding process with additional cold wire.Meanwhile,with the help of a high speed camera and arc analyzer,keyhole and plasma characteristics,arc characteristics and molten characteristics of additional wires were studied.It can be seen that the new process has good appearance,and compared to the conventional laser-MIG hybrid welding process,during this new welding process,the stability of weld penetration and reinforcement,as well as the characteristics of keyhole,plasma and arc were similar,but the deposition rate has a significant raise by 22%-68% without increasing heat input.Based on the laser absorption mechanism of metal materials,the effect of different materials on laser absorptivity were studied.The results show that penetration will increase after filling some wires that has a higher laser absorptivity than base metal,or penetration will decrease after filling wires.And it can be concluded that the difference of resistivity and electronic state of the materials leads to the difference of laser absorptivity,which may be a main cause of the difference of penetration.Lastly,with A6N01 S aluminum alloy of the high speed train sidewall,welding porosity,welding deformation,welding efficiency,microstructure and property of the weld were studied by using wobble laser-MIG hybrid welding process with additional cold wire,compared to wobble laser-MIG hybrid welding process.The results show that welding porosities of both welding processes are below 0.6%,and all the tensile strength of these welds are more than 75% of the base metal,compared to wobble laser-MIG hybrid welding process,during this new welding process welding deformation,welding efficiency and welding microstructure are similar,while the welding efficiency is increased by 23% without increasing heat input.