Research On Laser-arc Hybrid Welding And Weld Bonding Of Aluminum Alloy To Stainless Steel

Aluminum/steel composite joint can fully utilize the advantages of aluminum alloys and high-strength steels,and can greatly reduce structural weight while ensuring performance,and has a wide range of applications in aerospace,rail transportation,automobile body manufacturing and other fields,but due to the differences in thermal physical properties between aluminum and steel,especially the intermetallic compounds at the interface,which results that it is difficult to weld aluminum and steel,and limits the further application of aluminum and steel composite joint.Therefore,the paper studied welding process of aluminum/steel dissimilar metals by used the 6061 aluminum alloy and Q460 high-strength steel as welding base metals and used the laser-arc composite heat source as the welding heat resouce.Then the copper interlayer was added at the interface to improve welding forming.The intermediate layer of the alloy regulates the formation of aluminum/steel dissimilar metal welded joints.Finally,a new laser-arc-bonded composite joint of aluminum/steel dissimilar metal was formed by applying adhesive layer on the joint overlap area.At the same time,the advanced analysis and detection technology methods were used to explore the influence of the copper interlayer and adhesive layer on the mechanical properties,microstructure appearance,element distribution,and fracture modes of the aluminum/steel joint.The results showed that 6061 aluminum alloy and Q460 high-strength steel could be connected effectively by the laser-arc composite heat source.The best mechanical properties was 1.670 kN/cm without the copper layer.The joint eventually fractured at the Al/Fe metal intermetallic compound layer,and the fracture mode was cleavage crack;With the copper interlayer,the fusion braze joint and deep fusion joint could be formed under different heat source conditions.The best mechanical property of the deep fusion joint was 2.517 k N/cm.The joint eventually fractured at the transition zone between the heat affected zone and the inter layer of the aluminum alloy base metal,and the fracture mode was quasi-cleavage crack.The analysis of joint microstructure and element distribution showed that the copper interlayer could effectively inhibited the formation of Al/Fe intermetallic compounds,and the thickness of intermetallic compounds could be controlled within 10?m,but some Al/Cu intermetallic compounds was produced which dispersed in the aluminum alloy base metal;The experiment realized the laser-arc-bonded composite joint of aluminum/steel dissimilar metal and optimized the adhesive thickness.The best mechanical property of joint was 2.632 kN/cm when the adhesive thickness was 0.1mm,which the adhesive layer was only applied at the weld seam position.The best mechanical property of joint was 2.819 kN/cm when the adhesive thickness was 0.15 mm,which the adhesive layer was only applied at the full overlap position.The was organically combined of mechanical bonding strength and the metallurgical force of welding could greatly improve the mechanical properties of welded joints,and the research also found that the addition of the adhesive layer could further regulate the microstructure of the welded joints,the joint shape changed form a "V shape" type into a "dog teech shape" type.The melting aluminum alloy and the special "keyhole" of laser welding could provide a channel for the decomposition of the gas ashesive layer,the gas could completely escapes form the welding poor by adjusting the welding process parameters and limiting the adhesive thickness.