Research Of Cold Metal Transfer Welding Process Of 6022 Aluminum Alloy Sheet

Automobile body welding uses resistance spot welding technology.In order to achieve the tightness of the whole body,the gap between the solder joints should be sealed.Traditional welding technology use MAG(Metal Active-gas Arc Welding)technology to weld of longitudinal seam.However,there are many problems such as overheating,welding defects,rewelding needed and so on.In view of the problems existing in the welding process of lap joint,in order to achieve better welding results,this paper presents the use of CMT technology(Cold Metal Transfer)to replace the traditional welding technology MAG.CMT welding technology is a kind of improved gas metal arc welding technology.Compared with the conventional gas shielded arc welding technology,CMT has a lower energy input,which is largely lower than the others methods.Here we choose to use ER4043 Aluminum Alloy(with diameter 1.2 mm)as fillering material,and use 6022 Aluminum Alloy sheet(with thickness 1mm)as base material,to analyze the optimization of welding parameters of CMT aluminum alloy sheet.The microstructure of the Aluminum Alloy and its mechanic properties would be tested by SEM and Tensile testing machine.Then this paper analyzes the effects of welding wire feeding speed,arc length and welding speed on the forming and microstructure of CMT welded joints of aluminum alloy sheet.The seam of weld aluminum alloy sheet CMT is smooth and there is no obvious welding defects,also,the welding deformation of the joint is small.Aluminum alloy CMT weld joint regional is compact.The results show that the CMT welding for aluminum alloy sheet has achieved good results.About joint performance,its micro hardness distribution is not uniform.The lowest micro hardness value is obtained in the middle of joint,and then the highest value at the edge of the Heat-affected-zone.The tensile strength of the joint is just slightly lower than the Aluminum metal itself.After the observation,we found that the fracture mode is a ductile fracture at HAZ.With the increase of welding wire speed,weld bead in macro morphology has become increasingly wide,the weld color range is larger.The weld penetration and weld width increase,the depth-width ratio gets bigger,and HAZ gets larger.With the increase of the longarc correction coefficient,weld in macro morphology on the weld become slightly loose.The weld penetration and weld width increase,depth-width ratio gets bigger and HAZ gets larger.Instead of using the traditional MAG welding methods,CMT technology can be perfectly adapted to get a good joint for 6022 Aluminum Alloy sheet.Finally,we get the optimal parameters for CMT sheet for Aluminum Alloy are as follows: wire feeding speed is8m/min as wire feeding speed value,540mm/min as welding speed value,with just 5%correction for arc length.At last,this paper analyzed the difficulties of CMT welding of aluminum plates as well as the corresponding solutions.