KINETIC-STUDIES ON DEOXIDATION OF ALUMINUM KILLED LOW-CARBON STEELS USING SYNTHETIC FLUXES

Laboratory size (4.5 kg) low carbon steel melts were deoxidised using aluminium and FeAl (33%Al), with and without synthetic fluxes, in alum ina and zirconia crucibles. The dissolved oxygen, total oxygen, solubl e aluminium, insoluble aluminium, silicon, and carbon contents of the melts were determined as a function of refining time and temperature. It was observed that the reaction between aluminium and oxygen in solu tion closely follows thermodynamic equilibrium. Silica present in the alumina crucibles was found to be a source of oxygen for the melt, whe reas this was not the case for zirconia crucibles. Reoxidation of the melt occurred through oxygen pickup from the atmosphere. The extent of this reoxidation was found to be a function of the oxygen content of the bath and the extent of the slag cover on the surface of the melt. The effectiveness of calcium aluminate (12CaO.7Al2O3) based fluxes in protecting the melt from reoxidation and in increasing the rate of rem oval of inclusions was evaluated. Synthetic fluxes and refining techni ques were developed to obtain a total oxygen content of 0-001 wt-% wit hin the first 10 min of refining. IS/1070