Research On TIG And Laser Hybrid Welding Technology Of Medium Thickness Plate Aluminum Alloy

Arc-laser hybrid welding is an advanced welding technology by combining two heat sources with different physical characteristics and energy transfer mechanisms. It is widely used in welding of different metal materials by its advantages of large welding penetration, high welding speed, less deformation, good bridging ability, etc. For aluminum alloy material, due to its physical characteristics, making traditional welding method and laser welding method has certain limitations. Arc-laser hybrid welding technology has good adaptability for aluminum alloy. Currently, research on hybrid welding of aluminum alloy material mostly focus on high power laser and MIG arc compound, for research of TIG-laser hybrid welding of aluminum alloy is less. In this paper, the character of YAG laser+two types of TIG arc current hybrid welding on A6061aluminum alloy is investigated, the research offers a new instructional method for hybrid welding of aluminum alloy. Main research contents are as follows:(1) According to the existing laboratory equipment, a system of TIG-laser hybrid welding was developed, which include a low power YAG laser, a TIG welding machine, CNC machine tools, etc. Using this system, the welding parameters can be adjusted conveniently, which is beneficial to carry out the follow-up process test.(2) Surfacing welding experiment was conducted on5mm thick aluminum plate, to systematically research on the welding penetration, welding width and welding surface quality by two types of TIG arc current and laser hybrid welding. The experimental results show that when the arc current and laser power are high, the welding penetration got by TIG (AC)-laser hybrid welding is restricted to further increase, the other welding parameters impacting on TIG(AC/DC)-laser hybrid welding are basic similar. A dimensionless parameter Ψ was introduced to indicate the changes of heat sources interaction. Quantitative analysis results show that the coupling degree between TIG(AC) and laser along with the increase of arc current variation trend of first increased and then decreased, while the Ψ in TIG(DC)-laser hybrid welding continue to increase along with the increase of arc current. All these results illustrate the big difference between two hybrid modes, the analysis say that the difference comes from the electrode polarity itself characteristics and the influence of laser induced plasma. (3) Selecting typical welding bead which obtained by TIG(DC)-laser hybrid welding to conduct microstructure and microhardness analysis. The results show that there are large difference between different area of the welding seam microstructure in hybrid welding; The average microhardness of upper part of welding seam in hybrid welding is higher than welding seam in TIG(DCEP) which conducted in the same condition.(4) According to the generation characteristics, dividing porosity generated in hybrid welding into hydrogen porosities and keyhole-induced porosities. The results in studying on the keyhole-induced porosities by using single factor experiment method, show that we can restrict the keyhole-induced porosities by improving the molten pool of metal flow, increasing top opening diameter of key hole, stabilizing laser energy which enter into, preventing outside air into the keyhole, etc.