Generation Mechanism of MgO and Al2O3 Inclusions in 51CrV4 Spring Steel Based on the Ion–Molecule Coexistence Theory

作者：Jialiu Lei, Hangyu Zhu, Dongnan Zhao, Zhengliang Xue · 发表于：Metals · 年份：2019 · DOI：10.3390/met9080830 · 被引用次数：7 · 研究领域：Metallurgical Processes and Thermodynamics、Corrosion Behavior and Inhibition、Hydrogen embrittlement and corrosion behaviors in metals

The presence of MgO·Al2O3 inclusions in 51CrV4 spring steel is detrimental to the alloy’s castability and fatigue properties. To effectively suppress these inclusions during production, accretions were collected from the immersion nozzle, and the MgO·Al2O3 inclusions in the steel billet were investigated. The generation mechanism of the inclusions was evaluated based on the ion–molecule coexistence theory, and the mass action–concentration model of CaO–SiO2–Al2O3–MgO–FeO–MnO slag was developed. Industrial experiments showed that nozzle clogging was primarily caused by MgAl2O4 spinel inclusions, and the MgO·Al2O3 spinel inclusions in the steel billet were investigated by non-aqueous electrolysis. The model calculation results indicate that the Mg content increased with an increasing basicity, CaO/Al2O3 ratio, and Al content during the ladle furnace (LF) process. In contrast, the Mg content decreased with increasing CO pressure under Ruhstahl-Hausen vacuum degassing process (RH) conditions.