Shielding Gas for Welding of Aluminium Alloys （铝合金的焊接保护气体）.pdfVIP

International Journal of Modern Engineering Research (IJMER) Vol.1, Issue.2, pp-690-699 ISSN: 2249-6645 Shielding Gas for Welding of Aluminium Alloys by TIG/MIG Welding-A Review 1 2 3 Jyoti Prakash ,S.P.Tewari , Bipin Kumar Srivastava 1(Senior research scholar,Mechanical Engineering Department,IT- BHU, Varanasi (U.P.), India) 2( Professor, Mechanical Engineering Department,IT- BHU, Varanasi (U.P.), India) 3(Senior research scholar,Mechanical Engineering Department,IT- BHU, Varanasi (U.P.), India) Abstract: The shielding gas is used to protect the finished weld from the effects of oxygen and nitrogen in the atmosphere. Although the weld metal properties are primarily controlled by the composition of the consumable ,the shielding gas can influence the weld‘s strength, ductility, toughness and corrosion resistance. In general, for a given welding wire ,the higher the oxidation potential of a shielding gas, the lower the strength and toughness of the weld. This occurs because the oxygen and carbon dioxide in the shielding gas increase the number of oxide inclusions and reduce the level of materials such as manganese and silicon in the weld metal. When welding thick aluminium sections with pure argon as the shielding gas, porosity, lack of penetration and fusion defects can occur. The addition of helium to the argon shielding gas can significantly reduce these defects. This is because the high thermal conductivity of helium results in more energy being transferred into the weld. This in turn produces a hotter weld pool, resulting in improved fusion and slower freezing times, allowing any trapped gas more ti