Characteristics Of Laser Scanning Welding Process For 5A06 Aluminum Alloy Thick Plate With Narrow Gap

5A06 antirust aluminium alloy belongs to Al-Mg alloy,has good weldability,corrosion resistance,strength,along with the constant development of high performance aluminum alloy,aluminum alloy thick plate materials are widely used in aerospace,military industry manufacturing,machinery and other fields.Narrow gap lies in the groove size is small,the advantages of less filler metal,small welding linear energy and high cooling speed make weld residual stress and residual deformation significantly decrease,and compared with the conventional single laser heat source,laser scanning welding heat source area is large,can better control the welding defects such as porosity,incomplete fusion,especially in the welding of aluminium alloy,the advantage is more prominent.Therefore,we combine narrow gap with scanning laser technology to weld5A06 aluminum alloy with large thickness plate,and carry out research on narrow gap swinging laser multilayer welding for thick aluminum alloy.In order to realize the welding of 130 mm thick 5A06 aluminum alloy plate,this paper focuses on laser scanning welding of filler layer and laser self-fusion welding of bottom layer.Research has shown that other welding parameters under a certain condition,when the laser beam with circular trajectory,a scanning range is greater than1 mm,sweep frequency is greater than 80 Hz,can very good restrain the production of aluminum alloy in the weld process type air hole,at the same time also can improve the surface of the weld shape.Under the experimental conditions,the welding speed and wire feeding speed have little influence on the porosity and weld forming of narrow gap weld.For the laser self-fusion welding of aluminum alloy on the bottom layer,the increase of defocus and welding speed can enhance the stability of aluminum alloy welding pool,reduce welding spatter and reduce weld porosity.To explain laser scanning type stomatal inhibition of aluminum alloy welding process,and improve the inner mechanism of the weld,we was studied by means of high-speed video scanning welding parameters of molten pool flow characteristics and metal vapor/plasma wave characteristics.Experimental results can be summarized as:when the laser beam in a certain velocity(scanning frequency above 80 Hz),a motion radius(scan rate in more than 1 mm),and effect in circular path way to the welding area,can greatly enhance the stability of the metal vapor/plasma,extend its existing period,makes the molten pool flow direction at the same time,the stability is enhanced,the whole welding molten pool does not exist "backflow" phenomenon,at this time of theexistence of keyhole resistance decreases,the keyhole closed frequency is reduced greatly.Completed the first 130 mm thick 5A06 aluminum alloy thick plate laser scanning wire filling welding experiment,the sample test results show that: the weld porosity of1% on average,no side wall fusion,incomplete fusion,welding defects such as cracks,the weld area than the base material hardness reduced by about 10%,the average tensile strength of welded joint can reach 92.09% of the parent metal tensile strength.