Study On Development Of Oxide-based Activating Flux For Stainless Steel And Welding Technology

Abstract:A-TIG welding is a new variant of high-efficiency TIG welding using surface activating fluxes to improve weld penetration. In the present work, the development of activating flux for austenitic stainless steel and its welding technology have been carried out. The influence of10single-component oxide-based activating fluxes (SiO2、 Cr2O3、Al2O3、Fe2O3、CaO、MgO、CuO、NiO、TiO2、MnO) to the weld penetration, width and its micro structure on304stainless steel plates was investigated. After comparing their comprehensive effect on weld,7single-component activating fluxes were selected and the optimum activating flux was obtained by orthogonal test method L18(3’). Results show that the weld penetration of A-TIG welding is twice more than that of traditional TIG welding.304stainless steel plates with6mm,8mm and12mm in thick were welded without groove preparation by A-TIG welding method. Experimental results show that weld joint with full penetration and one-side welding with back formation and good appearance can be achieved in a single pass with A-TIG welding technology, and the mechanical properties of weld joints are qualified according to the relevant standards of stainless steel.Three different welding modes, namely, all-position DC (direct current) A-TIG welding, pulse A-TIG welding and step-pulse A-TIG welding have been employed to weld6mm thick304stainless steel piping with Experimental System for A-TIG Welding AD393CN from Ukrainian E.O. Paton Institute of Electric Welding in Kiev. Research indicates that for6mm thick304stainless steel piping without groove preparation, weld joint with full penetration and one-side welding with back formation and good appearance can be achieved in a single pass by these three types of A-TIG welding modes. Compared with the welding formation, micro structure and mechanical properties of the weld joints obtained by these three different A-TIG welding modes, those of step-pulse A-TIG welding are optimum, while DC pulse A-TIG welding comes in the second place.