Silicon Pick-up of Interstitial-Free Steel From MgO-SiC Refractories

The silicon pick-up of interstitial-free steel (IF steel) from resin bonded MgO-SiC refractories is studied via a medium frequency induction furnace. Samples of IF steel were heated in MgO-SiC crucibles with mould flux cover at 1 600 ℃ for 180 min. The silicon contents of IF steel samples taken from the molten steel in every 30 rain were examined and the refractories after heating were investigated by electron probe microanalysis (EPMA) with energy dispersive spectrometer (EDS). The silicon content of steel rapidly increased in the first 90 min of heating, and then decreased because of the formation of liquid layer on the refractory. Liquid layer separated the liquid steel from the bulk refractory and stopped the pick-up of silicon. At the same time, desilication via oxygen through the liquid layer and flux started to reduce the silicon content of the liquid steel.