Development of Flux Assisted Tungsten inert gas wedling process for modified 9cr 1Mo steel

Abstract

Gas tungsten arc welding is an essential welding process in situations where weld bead shape and control of metallurgical characteristics is required. However, it is associated with decreased productivity levels in situations where welding of large components are required. Stainless steel plates having a thickness between 2 and 3 mm can be welded in the Argon shielding with GTAW process underneath autogenous approach. The novel variant of conventional TIG welding which uses activated flux known as Activated Tungsten Inert Gas) welding (A-TIG) or Penetration Enhancing Gas Tungsten Arc Welding (PE-GTAW) was developed in 1960s by researcher of the Paton Institute of Electric Welding in Ukraine. newlineIn Activated Tungsten Inert Gas Welding, a thin coating of an active flux (which is nothing but chemical powder) is used to bring about a significant penetration in welding. In general, this impact is usually associated with the electrons capture in the arc s outer parts by high electronegative elements, which constrict the arc to bring about a similar effect to that utilized in plasma welding. The thin flux paste is melted due to high arc temperatures and the weld depth enhancement occurs primarily due to the arc constriction mechanisms or variation in the fluid flow direction. newlineThe A-TIG welding has previously been applied successfully to a vast variety of materials ranging from carbon steels to stainless steels, low alloy steels and upto super alloys. Grade 91 steels (Modified 9Cr-1Mo or P91 steel) are mechanical components which have been used widely for petrochemical and nuclear industry, in addition to power plants of elevated temperatures, owing to its higher ranking mechanical properties such as ultimate tensile strength, yield strength and creep rupture strength is exceeding or matching that of 304 stainless steel EM12, 2¼Cr-1Mo, 9Cr-1Mo and HT9. newline