Morphology of nonmetallic inclusions using silicon,aluminum, and calcium-silicon alloy in steel melt

The process of deoxidation of a 15 kg melt by silicon, aluminum, and calcium-silicon alloy was studied by continuously monitoring the dissolved oxygen potential using a solid electrolyte probe. Stable oxygen potential was established within two minutes, whether the deoxidizer was added onto the melt surface or plunged into the melt. Inclusion morphology was investigated with the help of optical and scanning electron microscopic studies. The inclusion index is dependent on the type of deoxidizer added, but was independent on the mode of addition. Thus, with ferrosilicon addition the index increased significantly which decreased very slowly on holding the melt while deoxidation with aluminum and calcium-silicon alloy resulted in a continuous decrease of the inclusion index. Evidence has been found to show that the reaction between the existing inclusion before deoxidizer addition and the deoxidizers added was also very fast.