Slag resistance mechanism of CaO·6Al₂O₃ refractory and its effect on inclusions of aluminum deoxidized steel

Abstract

In order to verify the advantage of CaO⋅6Al 2 O 3 (CA 6 )-based refractories on the inclusions of aluminum deoxidized steel, the five refractories, CA 6 , alumina, spinel, and CA 6 -alumina and CA 6 -spinel composition refractories were prepared into crucibles, and then the laboratory smelting experiments were conducted. After experiment, the slag resistance of the crucible and the variation on inclusions in steel were characterized and discussed. A dense CaO⋅2Al 2 O 3 (CA 2 ) layer, which was produced by CA 6 reacting with the slag, was distributed between the original bricklayer and the slag layer, improving the slag resistance of refractories. Meanwhile, the 12CaO⋅7Al 2 O 3 (C 12 A 7 ), generated by the reaction between CA 2 and refining slag, would release much Ca into the molten steel. The Ca would react with inclusions to produce low melting point substance to float up and remove, contributing to the reduction of the proportion of large size inclusions. In addition, typical inclusions in steel smelted with CA 6 crucible were small-sized MgO⋅Al 2 O 3 inclusions, whereas those of other crucibles are MnS-MgO⋅Al 2 O 3 composite inclusions with MgO⋅Al 2 O 3 as the core, implying CA 6 may absorb sulfur during the smelting process.

Effect of Al2O3 on Inclusion Removal in H13 Steels Using High-Basicity LF (Ladle Furnace) Refining Slags

“…However, the insufficient or excessive addition of calcium can result in high-melting-point inclusions, such as partially modified Al 2 O 3 or spinel inclusions, as well as CaS, which worsens the treatment effect [14][15][16][17][18]. Many scholars [19][20][21] used aluminum deoxidation slag and refining slag with a high desulfurization capacity to remove sulfur from steel. Zhao et al [22] demonstrated that refining slag can effectively control the plasticity and contents of the O, Al, and S in the inclusions.…”