Experimental Research On Laser Welding Of Ultra-thin Copper/aluminum Dissimilar Metals

In view of the increasing shortage of copper resources,this paper analyzes the current research status of copper/aluminum dissimilar metal material welding and then concludes to use ultra-thin copper/aluminum dissimilar metals instead of copper as usual in appliances because aluminum,who has low density and abundant resources,is second only to copper in electrical and thermal conductivity.However,the welding of copper and aluminum dissimilar metals faces big challenges because of the large differences in physical and chemical properties between copper and aluminum,and the welding of ultra-thin metals requiring very high technology.Therefore,this subject has carried out experimental research on laser lap welding of ultra-thin copper and aluminum dissimilar metals to find a better ultra-thin copper-aluminum dissimilar metal welding process by researching the effects of different scanning paths and the addition of nickel layer on the welding process window,joint weld formation,mechanical and electrical properties under the two overlapping modes of aluminum on copper and copper on aluminum and copper on aluminum were studied.The research results are as follows:(1)The single factor test of laser welding of copper/aluminum dissimilar metals obtains the welding process window,and the orthogonal test obtains the influence degree of welding factors on the surface weld formation of the weldment: welding power >welding defocus > welding speed,and forward defocus is beneficial to the welding of ultra-thin parts.(2)After adding nickel foil,the tensile strength of the composite joint becomes larger,and the influence rate of impurities and oxide layer on the joint surface weld perforation is extremely low.which verifies that the maximum gap margin of 0.1 mm copper/aluminum laser welding is 0.05 mm.(3)According to the surface weld defects and the working mechanism of laser,the welding mode of weldment is obtained.SEM,EDS and XRD were used to observe the microstructure and analyze the composition of the transition zone of the weld,and the forming mechanism of the weld was studied,which shows that nickel can effectively inhibit the diffusion of aluminum and reduce the formation of brittle intermetallic compounds.(4)The analysis of the tensile test,conductivity test and fracture position and fracture form of the joint shows that the welding process affects the shear force,the joint compound affects the conductivity of the joint,and the joint forms ductile fracture on the aluminum side.