Investigations on effect of CaO-CaF<inf>2</inf>-TiO<inf>2</inf>-SiO<inf>2</inf> based electrode coating constituents and their interactions on weld chemistry

This paper reports on the effect of CaO-CaF2-TiO2-SiO2 based electrode coating constituents and their binary, tertiary interactions on the weld metal chemistry of offshore structure. Coating compositions were prepared based on extreme vertices design methodology and extruded on austenitic 309L filler wire. Red ochre, a mineral waste from iron ore site, has been added to coating compositions in uniform quantity to utilize its iron content. Multi-pass weld beads hence deposited on super duplex 2507 grade steel were examined for chemical composition in terms of phosphorus, sulphur, molybdenum, niobium, and iron. Regression analysis was carried out to develop a relationship between the chemical composition and coating constituents, quantifying the effect of interactions. Obtained responses have also been optimized to find the most suitable coating compositions in the desired range of mineral constituents. The developed electrode coatings have been analyzed for their microstructure using scanning electron microscopy equipped with an energy dispersion spectroscope. The work establishes a relation between the coating minerals and their interactions on the weld chemistry.