The Research On Process And Mechanism Of Cu/W Dissimilar Metal Welded By A-TIG Arc Spot Welding

With the development of modern science and technology,the connection of dissim-ilar materials has become a hot topic in the field of welding.The welding problem of copper/tungsten dissimilar metals has attracted the at tention of scholars at home and abroad,the connection of copper/tungsten are important components facing armor in fusion reactors.In recent years,new applications are found on copper/tungsten compo-nents,in order to put the tungsten plate rolling into super thin in industrial produc-tion,due to tungsten is brittle and hard,it cannot curl.So the copper plate of good pla-sticity was used as the guide plate.The physical and chemical properties are different for copper and tungsten,it is difficult to weld tungsten and copper directly.In order to save cost and simplify the process.In this paper,the method of active TIG welding w-as introduced.In this paper,A-TIG welding method was applied to weld copper/tungsten dissimil-ar metals,the copper plate and the tungsten plate are connected with the joint structure,the copper plate is attached to the top of the tungsten plate and apply the activating fl-ux on the welding place of copper plate.Choosing four activating flux,the four acti-vating flux are SiO₂,TiO₂,CaF₂ and NaCl respectively,dissimilar metals Cu/W are welded by Tungsten inert gas?TIG?welding.The protective gas used in welding was argon.The arc shape of the welding process was filmed by high-speed camera.When the welding current were 110A and 140A,The results indicate that top surface of the welding spots coated SiO₂?NaCl are beautiful and regular.The top surface of the welding spots coated CaF₂ is poor.The top surface of the welding spots are no ob-vious difference between apply the TiO₂ activating flux and without activating fl-ux,the welding spot was general.When the current is 110A,only the speciments coa-ted SiO₂ activating flux can realize the connection of copper/tungsten;When the cur-rent is 170A,The top surface of the welding spots coated SiO ₂ activating flux are still regular,The surface of welding points coated TiO ₂ CaF₂,NaCl and uncoated activati-ng flux are similar,the surface of welding points were poor;It can be seen from micro-structure of joints,the tungsten side of the copper/tungsten interface is rough,few def-ects at interface of Cu/W coated SiO₂ activating flux,There are many defects at inter-face of Cu/W coated TiO₂,CaF₂,NaCl and uncoated activating flux,combination is u-ntightness at interface;The copper/tungsten connection mainly depends on the wett-ing of the liquid copper on the tungsten surface,during which the mutual diffusion of copper/tungsten has also occurred.When the welding current is same,the strength of joint coated with SiO₂ are higher than the coated TiO₂,CaF₂,NaCl activating flux,fracture of joint exists a large diff-erent.When the welding current is 110A,the fracture of the joints was separated from the welding spots,when the welding current were 170A and140 A,the fracture occur-ed at the thermal influence zone of the tungsten side near the welding spot.Fracture of joints of coating TiO₂?CaF₂?NaCl activating flux are separated from the welding spots.,it doesn't change as the current increases.In addition,in order to verify whether the scraggy at the interface affect the mech-anical properties of copper/tungsten joints,that is to say,effect of mechanical occlus-ion on the strength of copper/tungsten joint.laser marking machine of optical fiber w-as used in this paper.,the surface of tungsten plate is textured,Then,spot welding with copper and test its mechanical properties of joints.The results showed that the stren-gth of the welded joints was not improved after the processing.