Investigation On Laser-MIG Hybrid Welding Process And Microstructure And Properties Of 6mm SUS304 Stainless Steel

In recent years,the demand for stainless steel in petrochemical equipment,medical equipment,food industry and other industries is increasing.In the manufacturing process,the laser-arc hybrid welding method is considered as the key core technology to solve the complex structure of the narrow and medium-thick plates.This article takes6 mm SUS304 stainless steel as the research object.The SEM,EDS,EBSD and other methods are used to analyze the performance difference of laser-MIG hybrid welding joints at different welding speeds,which provides experimental foundation and theoretical basis for further promotion of laser-MIG hybrid welding engineering applications.Based on the welding seam forming characteristics of laser-MIG hybrid welding,a combined heat source model of double ellipsoidal heat source and Gaussian 3D heat source is constructed.The temperature field of laser-MIG hybrid welding of6 mm SUS304 stainless steel plate butt welding is realized by using sysweld software.In terms of macroscopic morphology of the weld,the difference between the simulated weld shape and the actual weld is less than 10%;in terms of microstructure,the difference between the calculated value of the secondary dendrite arm distance in different regions of the weld and the actual welding sample is less than 11%,which provides a basis for the formulation of welding process parameters.The effects of process parameters such as laser power,defocus amount,welding current(wire feeding speed),laser-arc distance and welding speed on the welding seam formation of laser-MIG hybrid welding were studied.Through the research,when the laser is in front and the arc is behind,laser-arc distance 2mm,laser power 6KW,defocus amount-2mm,welding current 180A(wire feeding speed 9.6m / min)and welding speed 2.2m / min.The welding joints is beautifully formed without cracks,pores,and inclusions.The average tensile strength of the joint is 778 MPa.In addition,under the conditions of this specification,when the butt gap is greater than 0.47 mm,the front of the weld seam begins to collapse,and overlap appears on the back of the weld.When the gap is greater than 1.12 mm,the welding process is unstable.The study found that the welds were mainly solidified by AF,and the solidified structure consists of a large amount of austenite and a small amount of ferrite.In addition,the weld grains are preferentially grown with <001> as the main orientation relationship.Grain size and heat affected zone grain size,dendrite arm spacing,and texture strength of the joint at a welding speed of 2.2 m / min are less than welding speed 1.2m/ min joints,but the deformation coordination,hardness and strength are better than joints with a welding speed of 1.2m/min.