Enhancing Mechanical Properties of Clean Steel by Combined Impurity Removal and Tailored Thermomechanical Processing

This study proposes a synergistic design strategy for clean steel that integrates effective purification with tailored thermomechanical processing. A proprietary impurity removal agent was employed to reduce the concentrations of O, N, and S effectively. Thermodynamic analysis provided quantitative guidance on deoxidation limits, while optimized processing parameters led to significant microstructural refinement. The resulting microstructure consists of a fine ferrite‐bainite matrix containing a high number density of nanoscale precipitates. This integrated approach yielded a superior combination of strength and toughness, with a yield strength of 487 MPa and a tensile strength of 635 MPa. The underlying mechanism was elucidated by first‐principles calculations, which revealed that a high cleanliness environment stabilizes the anionic states of residual impurities and enhances their covalent bonding with microalloying elements (Nb, Ti, V). This electronic‐level effect promotes the nucleation of refined, stable precipitates and correlates with a marked increase in shear modulus. By establishing clear correlations between impurity removal, microstructural evolution, and mechanical enhancement, this work provides a robust framework for precision precipitation engineering via chemical purification, outlining a scalable pathway for developing advanced high‐strength steels.