Study On The Effect Of 5A06 Aluminum Alloy TIG Weld Structure And Properties Under The Condition Of Ar-He Alternate Gas Supply

In recent years,with the development of welding technology,higher requirements and standards had been put forward for the goals of high efficiency,energy saving and economy.The 5A06 aluminum alloy material of the Al-Mg series is widely used in automobile shipping,manufacturing,aerospace and other fields.Because of its low density,high specific strength,good weldability and corrosion resistance.TIG welding(non-melting extremely inert gas protection welding)is the preferred method for aluminum sheet welding because of its ability to achieve high-quality welding for high-quality welding.The tungsten electrode itself has limited current carrying capacity,and the current and arc power are limited during welding,which leads to problems such as shallow weld penetration,high welding cost,and low production efficiency.On this basis,this paper proposes to use Ar,He alternate supply of the way to 5A06 aluminum alloy sheet TIG welding.The change law of arc pressure and arc pattern in the welding process of different gas transmission frequencies is studied.Explore the influence of different gas supply methods on the weld structure and properties,and provide help for actual welding production.Arc pressure and arc morphology in welding process were collected and analyzed by arc force testing device and high-speed camera.The results show that:Compared to the traditional gas delivery method of 67%Ar+33%He,the alternate supply mode of Ar and He reduces the arc pressure during welding.And the center pressure of the arc fluctuates.The gas delivery frequency fluctuates most at 1 Hz.As the frequency of gas transmission increases,the fluctuation of arc pressure gradually decreases.The gas delivery frequency is minimal at 4 Hz.Ar-He alternate gas supply can make the welding arc change significantly.Compared with the traditional mode of 67%Ar+33%He,the radial dimension of arc changes obviously at the frequency of 1 Hz and 2 Hz.The Ar arc is bell cover-shaped and he arc is spherical.When the gas supply frequency is 4 Hz,the arc shape is close to that of the mixed gas phase.Through the deep melting width comparison of welds,it is found that alternate gas delivery can increase the depth-to-width ratio of welds.Analysis of mechanical properties and corrosion resistance of welds obtained by 67%Ar+33%He traditional gas supply and 2 Hz alternate gas supply.The results show that:The welding arc pressure during the alternating Ar-He gas delivery produces periodic changes that cause the melting pool to stir when acting on it.The grains of the weld are refined,and at the same time,the two strengthening phases of Al₃Mg₂and Mg₂Si in the weld are more refined and distributed in a dispersed form.And compared with traditional gas delivery,the welding thermal influence area is narrower.When the gas supply frequency is 2Hz,the weld grain size is 23.9?m,which is the smallest.Analysis of mechanical properties and corrosion resistance of welded joints obtained by 67%Ar+33%He traditional gas supply and 2 Hz alternate gas supply.The results show that:Compared with the traditional continuous gas delivery,the average tensile strength of welded joints under 2 Hz alternating gas delivery conditions was 298.1 MPa.Which reached 94.5%of the strength of the master material,the average tensile strength was increased by 17%and the fracture method was toughness fracture.The average hardness of the 2 Hz alternating gas welded joints seam is 88.92 HV,and the average hardness is increased by 7.3%.The analysis of electrochemical experiments shows that traditional gas-delivering welded joints have better corrosion resistance.Through comprehensive analysis of weld structure and performance under different gas supply methods.It is concluded that in the TIG process of 5A06aluminum alloy,the use of Ar-He alternating gas supply method can refine the welded joints grain and improve the mechanical properties of the weld.The resulting welded joints performance is optimal when the gas delivery frequency is2 Hz.