Fundamental studies on the deoxidation of low carbon steels with ferrosilicon

Abstract

Laboratory size (4.6 kg) low carbon-iron melts were deoxidized using plain ferrosilicon, ferrosilicon with calcium aluminate flux, and ferrosilicon with calcium silicate flux. The dissolved oxygen and total oxygen contents in these heats were measured as a function of time and temperature using oxygen probes and quenched pin samples taken from the melts. The dissolved oxygen values, as measured by the oxygen probes, indicated that the iron-silicon deoxidation reaches equilibrium within five minutes of reaction time. However, the total oxygen (dissolved oxygen+oxygen in oxide inclusions), as measured from the quenched pin samples, took almost twenty minutes to reach a steady state. The two aforementioned features were common to all the experimental heats. Below 1978 K the ferrosilicon heats with calcium silicate or calcium aluminate flux had lower steady state total oxygen values as compared to the plain ferrosilicon heats; the difference was more significant at lower quenching temperatures. Also, below 1978 K, the dissolved oxygen-temperature relationship of flux heats was identical to their steady state total oxygen-temperature relationship, which indicated that the addition of fluxes leads to elimination of oxide inclusions. The performance of calcium aluminate and the calcium silicate fluxes in removing the oxide inclusions was found to be identical in these laboratorysize heats.