Research On Mechanism And Welding Processing Of Laser-double Electrodes TIG Hybrid Welding

Laser-arc hybrid welding technolgy has become an research focus in the field of welding at home and abroad because it combines the advantages of laser weld ing such as high power density,large depth-width ratio,low thermal input and deformation,fast welding speed with the advantages of arc welding such as low assembly accuracy,high energy utilization and low cost.In order to make full use of the advantages of laser welding and double electrodes TIG welding,the laser-double electrodes TIG hybrid welding is proposed and the corresponding test system is built.The heating process of this new type of laser-arc hybrid welding is studied,and the arc physical characteristics,molten pool characteristics,keyhole morphology,temperature field characteristics,weld structure and mechanical properties are deeply explored,which provides a new idea for the hybrid welding technology of medium and low power laser and TIG arc.The arc shape of composite welding was acquired by the camera,and the arc pressure and current and voltage signals were measured by "the method of static small hole" and current and voltage acquisition system.The results show that the arc of TIG with double electrodes will shrink further with the addition of laser,and the arc shape will and integrate and change from the double Gauss heat source to the distribution of ingot shape.The pressure distribution of the coupled arc is nearly circular,and the TIG currents,electrodes spacing and welding height will affect the peak and offset of arc pressure.The static characteristic curve of arc is "U" shape.The current of the two TIGs will have a cross-effect on their respective voltages,and the laser will make the conductive channel longer.The characteristics of molten pool,keyhole and temperature were acquired by a high-speed camera and a thermal imager,and compared with laser-TIG side hybrid welding and double electrodes TIG welding.The results show that laser-arc hybrid welding has high stability of keyhole and higher molten pool velocity than arc welding,and there will be "Carmen Vortex Street phenomenon".The upper surface of laser-double electrodes TIG hybrid welding keyhole is nearly elliptical,the lower surface is circular,and the whole is frustum.Compared with the two methods mentioned above,it has stronger penetration ability and less radiation to both sides in the same heat input.The surfacing and butt welding experiments of low carbon steel were carried out.The effects of different parameters on weld formation and the microstructures and properties of laser-double electrodes TIG hybrid welding were compared and analyzed.The results show that the method has the characteristics of double electrodes TIG welding and laser welding.The weld is beautifully formed and the cross section is nail-shaped.TIG1 mainly plays the role of preheating and increasing penetration.TIG2 is used for auxiliary heat and cover.Tensile property of joint is better than base metal,and the average tensile strength of weld metal is 530 MPa,and the fracture mode is ductile fracture.No cracks was found in bending test.The structure of coarse grain zone is coarser ferrite and pearlite,and the upper part of weld zone is tiny pre-eutectoid,side slab and acicular ferrite,while the lower part is mainly ferrite and pearlite.The hardness of it is higher than that of laser-TIG side hybrid welding and double electrodes TIG welding because of the existence and finer structure of pearlite.