Influence of flux agent composition on the ionization potential in A-TIG welding of the electrolytic tough pitch copper (Cu-ETP) sheets

Abstract

Due to its high thermal expansion coefficient and high thermal conductivity, welding of copper and copper alloys is considered difficult and demanding. Activated TIG welding (A-TIG) welding has been widely researched as a welding method for obtaining deeper penetration on various metals. However, A-TIG welding of copper remains unexplored without guidelines on the influence of flux agents and the influence of the applied parameters and achieved mechanical properties in produced welds. In this paper three agents were used as single component fluxes: calcium oxide (CaO), silicon dioxide (SiO2) and sodium carbonate (Na2CO3) for A-TIG welding Cu-ETP sheets. Welds were characterized by visual inspection and macrostructural analysis, also bend testing and tensile strength testing were conducted. Microstructure of the weld with optimal mechanical properties was analyzed by means of Field Emission Gun-Scanning Electron Microscope (FEG-SEM) and also the chemical characterization of the weld was made by means of Energy Dispersive Spectroscopy (EDS). The results showed that the most effective flux used was silicon dioxide. Welds welded with SiO2 showed good results in visual inspection, macrostructure analysis and band test and also have acceptable values of tensile strength. However, oxide inclusions have been found in weld metal in significant percentage which could indicate the possible degradation of electrical conductivity of the material.