Application Of TIG Welding In Corrosion Repairing Process Of Aluminum Alloy Cylinder Head

In recent years,the argon arc welding method has been widely used in the welding repair of alloy materials,but less in the repair of aluminum alloy cylinder head.In this paper,the corrosion problem of aluminum alloy cylinder head is studied,aiming to use aluminum alloy cylinder head after damage and improve the working performance and service life of the engine.This research is of great significance to reduce the expenditure of owner,improve the utilization of aluminum and reduce the pressure of aluminum alloy in the automotive industry.The choice of welding process parameters and the surface quality of the cylinder head will bring varying degrees of influence on the forming of welds in the welding process using argon arc method.This paper mainly analyzes the influence of welding current and shielding gas flow on welding quality,weld forming and mechanical properties and we use metallographic microscope and universal tensile testing to observe and test the morphology and mechanical characteristics.After that,the causes of cracks and stomata during the welding process are analyzed and discussed and suggestions are raised to avoid stomata and cracks.The results show that when the oxide film is present on the surface of the aluminum alloy cylinder head,the depth ratio of the weld is small and the quality of welding is poor.In the welding process,the welding depth increases with the welding current growing and with protection of gas flow still increasing,the weld penetration increased first and then reduced.Boundaries of aluminum alloy cylinder head weld and heat affected zone are very obvious.The welding grains are small and isometric and heat affected zone grains are coarse with the observation by the microscope.Through the tensile test,the fracture usually occurs in the heat affected zone,and the fracture of the welded joint is mostly brittle fracture.Welding current is an important factor affecting the quality of welding,no matter small or large of the current will also affects the mechanical properties of welded joints.In this paper,we control the welding gas flow as 15L/min and use different degrees of current to weld the aluminum cylinder head.The results show that when the current is 45 A,the mechanical properties of the welded joint can reach the highest,which is about 80% of the base metal.Addition of wire and post-weld heat treatment can further enhance the organizational properties of welded joints.The main reason for the existence of stomata in the weld of the aluminum alloy cylinder head is that the decomposition rate of argon is so fast during the cooling process that forming the argon pores and pores in the base metal becoming bigger and bigger during the welding process.Therefore,we can eliminate the pores in the weld by surface treatment and selecting a reasonable welding process.The main reason for the formation of cracks is the presence of other low melting point metal in the aluminum cylinder head,which is easy to evaporate during the welding process.Therefore,a reasonable welding process,preheating and heat treatment after welding,reduction of heat output,adjunction of the wire and other methods can effectively prevent the welding of crystal cracks.