Research On A-TIG Welding Activating Flux And Process Optimization For Low Carbon Steel

A-TIG welding technique is a new welding method of traditional TIG welding, with thepurpose of getting a larger welding penetration, by coating activator flux on the surface of thejoints. It can achieve an excellent welding quality of plate or tube with medium thickness,through one side without adding wire welding or opening gap in the joints. Therefore,carrying out the study of activator flux formulation and process parameters of A-TIG weldinghas relatively high academic value and economic benefit.Carry out the experiments to design and optimize activator flux formulation for Q235low carbon steel in A-TIG welding. Through the monopropellant activator flux plate weldingexperiment, we can pick out four oxides--Cr₂O₃, SiO₂, Fe₂O₃and TiO₂, which can play anactive role in increasing the depth of penetration with a preferred ratio of depth to width.Through the orthogonal test of the multi-component activator flux, we can summarize theinfluence of multi-component activator flux with different proportions on the weldingpenetration, and optimize the composite activator flux formulation AT-03, in which SiO₂, TiO₂,Cr₂O₃and Fe₂O₃account for the mass fraction of8%,52%,10%and30%respectively.Design the orthogonal experiment of welding process parameters for low-carbon steel,analyze each plate welding joint’s welding penetration depth, width and forming quality, andsummarize the welding pool molding law affected by the process parameters such as weldingcurrent, welding speed and arc length. In the case of keeping other process parametersconstant, the depth and width of welding penetration increase with the increase of currentintensity, decrease with the increase of the arc length, and show a decreasing trend with theincrease of the welding speed overall. Then, carry out single factor variable experiments ofwelding current and welding speed, in the condition of keeping other process parameters fixed.For Q235low carbon steel, there is a certain interval range of A-TIG welding work current,which can promote welding penetration depth increase greater than the width in the range of160A to200A, obtaining a narrow and deep welding shape. When the welding machine’spower keeps in a certain extent, welding speed also has an optimum work range. For low carbon steel with thickness of8mm, welding speed which ranges from72mm·min^-1to88mm·min-1can bring about excellent welding penetrations.Finally, carry out shape optimization design of A-TIG butt joints based on the geometryparameters, and analyze Von Mises stress distribution of the welding joint models throughfinite element analysis. When load, plate thickness and other factors remain unchanged,within a certain range the shape between the welding zone and the base metal translates moresmoothly, smaller the stress concentration near the joint is. Therefore, joint shape’s designbased on geometry parameters and its simulation analysis can provide a useful reference forthe butt joint specimen’s shape design and processing in actual.