The Effect of TiO2 in the Ladle Slag on Inclusion in Ti‐Bearing Steel

• Published in: Steel research international Vol. 93; no. 10
• Main Authors: Zhao, Mao‐Guo, Liu, Hao, Wang, Xu‐Feng, Chen, Gu‐Jun, Wang, Qiang‐Qiang, Zhang, Xu‐Bin, He, Sheng‐Ping
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.10.2022
• Subjects: Aluminum oxide; Bearing steels; Castability; inclusion; Inclusions; Ladle metallurgy; Ladles; Liquid alloys; Liquid phases; Magnesium oxide; Slag; Spinel; Ti-bearing steel; Titanium carbide; Titanium dioxide; Titanium oxides
• ISSN: 1611-3683; 1869-344X
• DOI: 10.1002/srin.202200239

To improve the castability of Ti‐bearing steel, the knowledge of inclusions formed in liquid steel, affected by the slag composition, must be obtained. In this study, the effect of TiO2 in ladle slag on inclusions in this steel at 1873 K is investigated. Experimental results indicate that Ca–Mg–Al–Ti–O complex inclusions, complex TiN inclusions containing MgO–Al2O3–TiOx cores, Ti–C–S inclusions, and TiC inclusions appear in the steel samples. The cores in TiN inclusions are mainly in the liquid and liquid + spinel fields before slag addition. When the steel reacts with slag containing 0% TiO2 for 1 h, the inclusions in the steel are mostly in the MgO + liquid + spinel and MgO + liquid field and have the highest MgO content. When the steel reacts with slag containing 5%≈20% TiO2 for 1 h, most inclusions are liquid slag + spinel and liquid slag phases. The average liquid fraction in most inclusions is higher than 60%. The ratio of the (mass percentages Ti3+) to (Ti3++mass Ti4+) in most liquid phases is approximately 50%≈70% for these oxide cores. Increasing TiO2 content in slag increases log(aAl2O3/aMgO3), which in turn decreases Mg content in the steel. This decreases MgO content in MgO–Al2O3–TiOx type inclusions. The laboratory experiments and thermodynamic calculations are adopted to investigate the effect of slag composition on the composition of inclusion in the steel. The complex TiN inclusions contained MgO–Al2O3–TiOx cores are mainly found in the steel sample. The phases of these cores are liquid and liquid +spinel. The slag containing higher TiO2 makes MgO content in the MgO–Al2O3–TiOx cores decreased.