Interaction between Molten Al‐Killed Mn–B Steel and Carbon‐Bonded MgO Refractories Based on Recyclates

This work investigates the high‐temperature interactions between low‐sulfur Al‐killed Mn–B steel and carbon‐bonded magnesia (MgO–C) refractories containing 0 and 50 wt% recycled material (recyclates). Finger immersion tests are conducted at 1600 °C under an argon atmosphere, with variations in boron (B) and sulfur (S) content. Microstructural and chemical analyses via scanning electron microscopy/energy‐dispersive X‐ray spectroscopy reveal the formation of protective MgO and CaS layers at the steel–refractory interface, alongside spinel (MgAl ₂ O ₄ ) and calcium silicate phases. B and S jointly influence wetting and infiltration behavior, while increased S promotes thicker CaS layers. Recyclates introduce microstructural heterogeneity (distributed dissolution sites) but do not significantly alter the interfacial reaction mechanisms. Both refractories exhibit comparable performance in forming protective layers, suggesting that recyclate‐containing MgO–C materials can serve as sustainable alternatives without compromising thermochemical stability or steel cleanliness. These findings support the use of recycled materials in refractory manufacturing, contributing to waste reduction and circular economy practice in steelmaking.