Study On Porosity Suppression In Rotating Laser-Arc Hybrid Welding Of Aluminum Alloy

As a high-strength and heat-treatable aluminum alloy,A6N01S-T5 has excellent comprehensive physical properties such as low density,high strength and easy machining and forming,and is now used in the body manufacturing of high-speed trains.Compared with conventional arc welding method,laser and electric arc hybrid welding technology as a new welding technology,combined with the characteristics of the laser and electric arc heat source,has high welding speed,less thermal damage to the material,less welding deformation,the weld surface forming well and so on,so in high-speed train car body welding of aluminum alloy has strong application prospects.The present study shows that the aluminum alloy has porosity defects in the laser welding process,especially in the non-permeable welding seams,which is closely related to the keyhole stability in the laser welding process.With the development of beam forming technology,by applying rotation to the laser heat source,the keyhole can be kept in a relatively stable state,thus improving the stability of the keyhole.The key point of this paper is how to solve the problem of the porosity in the laser welding process of aluminum alloy under the condition of making full use of the advantages of rotating laserarc hybrid welding.By high-speed camera A6N01S-T5 aluminum alloy welding process monitoring,compared the rotating laser-arc hybrid welding with conventional laser-arc hybrid welding,keyhole stability under two kinds of welding methods,the main observation and statistics of keyhole cyclical change,such as number of closed,splash,opening diameter changes,the relevant data such as current voltage.It is found that the closing times of the rotating laser keyhole are less than that of the conventional laser keyhole in the same time period.The diameter of the keyhole produced by the rotating laser does not fluctuate greatly,but is in a relatively stable and small dynamic change process.The spatter amount of rotary laser welding is less than that of conventional laser welding,the size of the spatter is smaller,and the height and range of eruption are smaller,indicating that the stability of keyhole under the action of rotary laser is stronger.The optimized rotation laser parameters(rotation frequency: 50 Hz,rotation radius: 1mm)were used for the welding test,and the following results were obtained: 1.The weld surface is well formed;2.The weld penetration decreased slightly from 4.8mm to 4.0mm;3.The porosity of the weld decreased from 8.41% to 5.68%.In the butt joint experiment: 1.The width of the softening zone of the joint welded at the same time did not increase significantly due to the increase in the width of the rotating laser heat source;2.The joints have excellent tensile properties(the joint coefficient is 70%),and the comprehensive mechanical properties of the welded joints obtained under this parameter are the best.