FORMULATION OF FLUX FOR SUBMERGED ARC WELDING

Abstract

Submerged arc welding process is the most widely used arc welding process for joining thick plates and pipes. This welding process is different form the other welding process in the sense that arc is blanketed with granular material. This material is known as flux. The properties of the weld metal depend upon flux-electrode wire and base plate combination. Flux composition has been found to affect the chemical composition of weld deposit and characteristics of slag influences the the mechanical properties-tensile strength, fatigue strength etc. of the weld deposit. Thus, flux play a dominating role on submerged arc welding in determining desired properties of a weld joint. Silica based fluxes, in general act as a source of. dissolved oxygen. Low oxygen content is desirable in the weld deposit of steel. That's why in the present investigation CaO-Al203based fluxes have been used. The present CaO-A1203 based fluxes along with other constituents in varying proportions like Ti02, CaF2, MnO2 and Al203 have been designed with the help of available binary and ternary phase diagrams. The selection criteria of different flux compositions has been their liquidus temperature. The fluxes have been prepared by agglomeration technique using sodium silicate as binder. The size mix of different fluxes, electrode diameter, current, voltage and speed were more or less kept constant. The basicity of different fluxes was varied in between 1.38 to 2.06. Fluxes were subsequently used for laying multi layer pad on mild steel plate using the same welding parameters and electrode wire. The present work is mainly confined to the transfer of elements namely carbon, manganese and silicon to the weld metal under the influence of different fluxes. For the analysis of the elements like C,Si and Mn the top layer of the deposit was chosen to minimise . - ." the dilution. C, Si and Mn of the samples are tested by Strohlein apparatus, gravimetric and volumetric methods respectively. With the help of obtained data, a relationship has been developed between the flux Combination and the gain or loss of these elements during welding