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

In order to verify the advantage of CaO center dot 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 center dot 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 center dot 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 center dot Al2O3 inclusions, whereas those of other crucibles are MnS-MgO center dot Al2O3 composite inclusions with MgO center dot Al2O3 as the core, implying CA(6) may absorb sulfur during the smelting process.