Research On High Strength Al-alloy Automatic Welding Process With Robotized Double-side Arc Welding

20mm 7A52 Al-alloy plates were used as base material in the experiment. Robotized and automatic double-side TIG arc welding (DSAW-TIG) was adopted in Backing welding,double pulse MIG(DP-MIG) welding was adopted in filling welding.A robotized double-side arc welding station was built to realize double side arc automatic and synchronous welding.The backing weld was welded by double-side TIG arc welding(DSAW-TIG) in a coaxial way to explore the relationship between welding parameters and welding formation/quality. Results showed that in the line energy range of 5KJ/cm-10KJ/cm in self-fluxing DSAW, reducing the welding speed and increasing the line energy would help reduce gas hole defects(Porosity down from 1.12 poles/mm2 to 0 poles/mm2).The shape of the weld cross section changed from nallow-X→wide-X→Rectangular.Taking welding line energy,fill area,the processing cost stability and welding process into account to explore applicability of several groove forms.Results showed that groove with double V and 6mm blunt edge was the best in all grooves in DSAW-TIG welding.Typical defects(pore,hot crack,lack of fusion,etc.) of aluminum alloy DSAW welding process was discussed, especially over-welding defect lead to the double sided arc edge heat cutting effect,and widespread collapse of weld metal.Comparison of self-fluxing with will-filled backing welding process of DSAW-TIG were made,self-fluxing welding process was more simple and efficient than the wire-filled welding process,the hardness of the self-fluxing joints is 11HV higher than that of wire-filled joints,8HV lower than base metal. The composition (Mg,Zn) of the self-fluxing joints from the base metal to the weld changed steadily,while in the wire-filled joints is Mg↑,Zn↓ with less MgZn2 forming. The two has similar microstructure composition,but microstructure of wire-filled joints layered with colors of white and black,which lead to the deterioration of mechanical properties of the joints. The weld coefficient of self-fluxing joints is 71.7%,while the Weld coefficient of wire-filled joints is 44.7%.Completed the double pulse MIG filling test, The main phases in the double pulse MIG filling weld are mainly a (Al) and Mg2A13.The microstructure of filling weld on self-fluxing backing weld (former) and wire-filled backing weld (latter) are overall similar,except the transition area.Microhardness and tensile properties are also generally at the same level. The hardness of weld is about 75HV, Weld coefficient is about 42%,and the former mechanical performance is slightly better than the latter.