| The demand for sheet stainless steel in the aviation,nuclear power,construction and rail industries is increasing,Laser-TIG hybrid welding technology is one of the common welding processes in stainless steel,However,the welding efficiency of this technology is relatively lower because of high current can not through the tungsten electrode and slow dissolution rate of welding wire.A new type of hybrid welding method of laser-K TIG hybrid welding technology is proposed,at the same time,a systematic study of laser-K TIG hybrid high speed welding technology for stainless steel sheet will be carried out.The K-TIG arc shape during the hybrid welding process is acquired by high-speed camera,and the arc characteristics are analyzed in combination with image processing technology.The results show that the proper energy ratio is an important factor to ensure the stable combustion of arc.When the action position of the laser is near the anode,the cross section of the arc and the laser energy absorbed by the arc plasma are increases,when the position of the laser focus is close to the cathode,the cathode region of the arc fluctuates violently and the arc stability decreases,theoretically,the defocusing amount of laser-K TIG hybrid welding is-4?0mm,the heat source spacing of laser-K TIG hybrid welding is 0?3mm.First of all,with 10mm plate thickness of 304 stainless steel as the research object,a large number of welding tests by adjusting the process parameters,and with the help of SPSS software processing data,obtain the main process parameters affecting weld melting depth and melting width to provide relevant guidance for the subsequent high-speed welding of sheet stainless steel.The test results show that in the process of laser-K TIG hybrid welding,laser in the front of arc,their axis has an angle of 15 degrees.Weld melting depth is mainly related to laser power,welding current,welding speed.Secondly,with sheet stainless steel as the research object,the feasibility of high speed welding is explored by comparing the welding quality,welding speed and heat input of laser-TIG hybrid welding and laser-K TIG hybrid welding.The results show that 4mm Stainless steel single-sided welding duplex forming test,laser-K TIG hybrid welding speed of TIG hybrid welding technology is 2m/min,which is twice times of laser-TIG hybrid welding speed,and the unit heat input is 0.43 of laser-TIG hybrid welding technology.Finally,taking 4mm thick stainless steel as the research object,the optimization test of high speed welding of stainless steel is carried out and a set of optimized process parameters are obtained,the specific parameters are P=3.5kW,I=200A,V=2m/min,DLA=0?2mm,?f=-1.5?0mm,the weld forming is good when the clearance is weld gaps less than 0.5 mm and stagger joint is less than 1 mm.The comprehensive performance of laser-K TIG hybrid welded joints was tested,including metallographic tissue analysis,electrochemical corrosion test and mechanical properties test.The test results show that the microstructure of laser-K TIG hybrid welded joints is mainly composed of austenite,skeleton ferrite and strip ferrite,and there are obvious fusion transition zones in the thermal influence zone and weld area,and the hardness value of weld is around 320HV,which is much higher than that of the base material,but the hardness value near the fusion zone will decrease obviously.The tensile strength of the weldment is 648MPa,the fracture is the base material area,and there is no crack in the weld at the 1800 of the positive bend and the back bend,and the corrosion resistance of the weld area is higher than that of the base material area by comparing the electrochemical corrosion behavior of the weld and the base material in the NaCl.The research work in this paper shows that the welding quality and welding efficiency of laser-K TIG composite welding are better than laser-TIG composite welding technology,and the mechanical properties and corrosion resistance of the joint are higher than that of the base metal,which can meet the needs of practical industrial applications. |
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