Influence of Ca-Al Deoxidizer on the Morphology of Inclusions

Abstract

In order to make clear the influence of Ca-Al deoxidizer on the shape control of Al₂O₃ and MnS inclusions which cause the anisotropy of the Al deoxidized steel, experiments of Ca-Al deoxidation for the Al predeoxidized steel have been carried out. And a formation mechanism of the inclusions characteristic to this deoxidation are discussed. The results are summarized as follows:
(1) Inclusions in the molten steel change to low melting ones consisted of Al₂O₃-CaO-CaS in which CaS distributed uniformaly.
(2) Inclusions in the ingot change to complex type consisted of Al₂O₃-CaO-(CaS) in which CaS deposits peripherally. These complex inclusions are thought to he formed by precipitation of CaS due to the solubility drop during solidification process.
(3) The anisotropy of the steel is improved by this shape coatrol of inclusions.