Mineralogical Study on the Source of Exogenous Inclusions in Steel

Abstract

In order to know the source of macroscopical inclusions by mineralo-chemical method, mineralogical composition and microscopical structures of exogenous source substance in steelmaking process of bottomand top teeming ingot were investigated in connection with those of ingot scums.
The following conclusions were obtained.
(1) The values of CaO/SiO₂, CaO/Al₂O₃ and (Fe, Mn) O/SiO₂ of exogenous source substance fell gradually with progress of casting process, and the values of constituent minerals of ingot scums were equal to those of altered refractories at the end of casting process.
(2) The chemical and mineralogical composition of ingot scums was similar to that of altered refractories at the end of casting process, and it was considered that mixing of these altered refractories played an important part in forming ingot scums.