Formulation and Production of Arc Welding Electrode Coated with Mill Scale Based Flux Locally Sourced from Ajaokuta Steel Company Limited in Nigeria

Abstract

This research is targeted at locally produced iron (Fe) based arc welding electrodes, using mill scales from Ajaokuta Steel Company Limited (ASCL). Mill scale was collected, prepared into pulverized form and analyzed using X-ray fluorescence spectrometer machine. The result of the analysis showed predominantly (more than 96%) iron, which is an important constituent of iron oxide electrode coatings. The flux compositions were generated using Hadamard multivariate chemical model, by which fifteen different flux compositions were formulated within given trial ranges of the constituent flux elements. Three of the flux compositions formulated were used for the coatings of the electrodes. The percentage compositions of the three different fluxes were A(X1=40%, X2=25%, X3=15%, X4=8%, X5=5%, X6=3%, X7=4%), B(X1=43%, X2=25%, X3=10%, X4=10%, X5=5%, X6=3%, X7=4%) and C(X1=44%, X2=30%, X3=10%, X4=8%, X5=3%, X6=3%, X7=2%). Where X1=mill scales, X2=sodium silicate, X3=calcium carbonate, X4=manganese dioxide, X5=silica, X6=calcium fluoride and X7=feldspar. The elemental composition of the mill scale, using the modern XRF machine shows that Fe, Ti and Mn were found to be major constituent elements, with Fe constituting more than 96% of the total contents. Other elements such as P, Cu, Ni and Cr were found to be present in traces. Also the elemental compositions of the steel core wire used for the research was found to be within the specification of mild steel, according to ASTM standard which states the percentage of carbon for mild steel as 0.05 – 0.25%, Manganese not to be more than 1.65% while Silicon should not be more than 0.6%