<p>The erosion patterns of MgO·Al₂O₃ spinel as a crucible material in special steel smelting and its impact on molten steel cleanliness are investigated. MgO·Al₂O₃ spinel refractories used in industrial high-nitrogen stainless steel bearing steel smelting are analyzed and tested. Results indicate that during vacuum carbon deoxidation, MgO·Al₂O₃ spinel partially decomposes, and the released [Mg] reacts with Al₂O₃ inclusions in the steel to form MgO·Al₂O₃ inclusions, promoting inclusion flotation and improving molten steel cleanliness. Due to the unique structure of MgO·Al₂O₃ spinel, iron diffuses into the spinel form MgAl_1.9Fe_0.1O₄, which prevents further erosion. The high-pressure nitrogen smelting process also causes a small amount of AlN on the surface of the MgO·Al₂O₃ spinel crucible, further enhancing its high-temperature performance. After smelting, a deposit layer primarily composed of MgO, Al₂O₃, and MgO·Al₂O₃ spinel forms on the inner wall of the crucible, indicating that floating inclusions adhere to the spinel surface, thereby reducing the incorporation into the steel and improving molten steel cleanliness. These findings provide a theoretical foundation for broader application of MgO·Al₂O₃ spinel as a crucible material in the field of high-quality steel.</p>