Reaction Mechanism between MgO and MgOC Lining Refractories and a High‐Carbon Al‐Killed Steel

In the current study, effects of a carbon‐bonded magnesia (MgOC) refractory and a magnesia (MgO) refractory on the cleanliness of a high‐carbon Al‐killed steel and on the degree of refractory are investigated using laboratory experiments, thermodynamic calculation, and a kinetic modeling. The refractory/steel interface layer and inclusions in the steel are analyzed. After a 90 min contact between the refractory rod and the steel, the penetration of the molten steel into MgO refractory is small. An about 0.1 mm thick interface layer containing CaO–Al 2 O 3 –SiO 2 –MgO is generated at the boundary of magnesite particles while the composition of inclusions in the steel changes very little. The molten steel penetrated 1 mm into MgOC refractory through grain boundaries, forming channels due to the graphite consumption. A new 20 μm thick interface layer containing CaS and MgO is formed between the steel and MgOC refractory. The formation of CaS is favored at the steel/MgOC refractory and is rarely existed at the steel/MgO refractory during cooling process. The average content of MgO in inclusions increases from 6.22 to 30.05 wt% while the Al 2 O 3 content in inclusions decreases from 84.57 to 69.95 wt% reacting for 90 min.