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Open AccessArticle

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

1
School of Materials Science and Engineering, Hubei Polytechnic University, Huangshi 435000, China
2
The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, China
*
Author to whom correspondence should be addressed.
Metals 2019, 9(8), 830; https://doi.org/10.3390/met9080830
Received: 1 July 2019 / Revised: 22 July 2019 / Accepted: 24 July 2019 / Published: 26 July 2019
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. View Full-Text
Keywords: MgO·Al2O3 inclusions; mass action–concentration model; slag basicity; CaO/Al2O3 ratio; ion–molecule coexistence theory MgO·Al2O3 inclusions; mass action–concentration model; slag basicity; CaO/Al2O3 ratio; ion–molecule coexistence theory
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Lei, J.; Zhu, H.; Zhao, D.; Xue, Z. Generation Mechanism of MgO and Al2O3 Inclusions in 51CrV4 Spring Steel Based on the Ion–Molecule Coexistence Theory. Metals 2019, 9, 830.

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