Research Progress and Prospect of Ultralow Phosphorus Steel Smelting Technology

Ultralow phosphorus steel (phosphorus content ≤ 0.005%) is a key material for high‐end equipment manufacturing in fields such as nuclear power, marine engineering, and high‐pressure vessels, where phosphorus content control is the core technology. Molten steel dephosphorization is mainly influenced by thermodynamic conditions, rephosphorization control parameters, and smelting processes. This article reviews the development history of ultralow phosphorus steel smelting technologies. Based on dephosphorization thermodynamics and reaction mechanisms, the effects of slag basicity, oxidizability, temperature, and phosphorus distribution ratio on dephosphorization performance are analyzed. The technical characteristics, dephosphorization efficiency, and applicable scopes of the double‐slag method, slag‐retaining method, and duplex process are compared. These three processes resolve thermodynamic contradictions through time separation, slag system circulation, and spatial separation strategies, respectively. Currently, the composite “slag‐retaining + double‐slag” process has been industrially applied. In the future, the smelting of ultralow phosphorus steel will develop toward the integration of multiple processes, intelligent precise control, low‐carbon green production, and whole‐process collaborative optimization, providing theoretical and technical support for the stable production of low‐phosphorus and ultralow phosphorus steels.