On the Nonmetallic Inclusions of a Bearing Steel Treated with Acidic Slag

Study on the treatment of molten steel with synthetic slag-I

Abstract

It is interesting that when molten steel has been treated with various synthetic slags, the latter is presumed to have some effect on the nonmetallic inclusions and the steel quality.
A bearing steel (C1.04, Cr1.5%) treated with synthetic acidic slag (A) was compared with a non-treated similar steel (B) with respect to inclusions and steel qualities. The deoxidizers used are Al, Al+ Ca-Si and Ca-Si.
The steel (A) contained more oxygen than the other steel (B), but with respect to the chemical composition, cleanliness, results of sand mark test and macro-etch test, both (A) and (B) were almost equal.
There were found elongated inclusions (A-type) in a bearing steel added with deoxidizer Ca-Si and treated with acidic slag. An examination of the inclusions by transmission electron diffraction showed that the inclusions consisted of a-tridymite or fayalite.
Therefore, the elongated inclusions in steel (A) presumably consisted of FeO-Si0₂ system.
Thus the aforementioned on the treatment of molten steel with synthetic slag evidenced that the slag treatment would control nonmetallic inclusions in steel.