EFFECT OF FLUX COMPOSITION ON ELEMENT TRANSFER DURING SUBMERGED ARC WELDING

Abstract

The properties of the weld metal have been found to depend upon the welding parameters and the flux - electrode wire - base plate combination. Flux composition has been reported to affect the distribution of different elements between metal and slag. The weld metal toughness, besides being affected by its chemistry, had been found to be impaired by presence of dissolved oxygen. Silica based fluxes, in general, act as a source of dissolved oxygen.For welding of quality steels, it is desirable that the level of dissolved oxygen should be kept as low as possible. In the present investigation, therefore, silica free fluxes have been used. The fluxes, based on Ca0 - Alz03 system alongwith other constituents in varying proportions like MgO, T102 , MnO, and CaF2 have been designed with the help of the available binary and ternary phase diagrams. The selection criterian of different flux compositions has been their liquidus temperature. The fluxes were prepared by agglomeration technique using sodium silicate as binder. The size mix of different fluxes was kept uniform. The basicity of different fluxes varies between 0.795 and 4.430. The fluxes were subsequently used for laying multilayer pad on a mild steel plate using the same welding parameters and electrode wire. The present work is primarily confined to the transfer of elements namely silicon, manganese and carbon to the weld metal under the influence of the different fluxes. The top most weld bead from the central region was analysed for Si and Mn using Atomic Absorption Spectrometer and carbon by Carbon Sulphur analyser. With the help of the above data, a relationship has been developed between the flux composition and the gain or loss of these elements during welding. The results show that the