Effect of Al content in molten steel on interaction between MgO-C refractory and SPHC steel

The effect of Al content in molten steel on the interaction between SPHC steel (0.005-0.068 wt.% Als and 19 x 10-4-58 x 10-4 wt.% O) and MgO-C refractory (11.63 wt.% C) was investigated. Non-metallic inclusions in the steel were examined at various periods (0, 5, 15, 30, 45, and 60 min) as well as the MgO-C interface after 60 min of corrosion at 1600 degrees C. The results show that when MgO-C refractory comes into contact with SPHC steel, the refractory interface consists of three layers arranged from the innermost to the outermost, including the original refractory layer, the dense MgO layer, and the iron infiltration layer. The carbon in the MgO-C refractories and the Al content in the molten steel undergo a reaction with the MgO in the refractories, resulting in an increase in Mg concentration in the steel. Increasing Al content in the molten steel from 0.005 to 0.068 wt.% causes a spinel layer to appear at the interface, and the disappearance time of Al2O3 inclusions in the steel decreases from 60 to 30 min, while the average MgO content in inclusions increases. Therefore, controlling the Al content in the molten steel and the smelting duration can help regulate the formation of spinel inclusions in the steel.