Thermodynamic calculation and MnS solubility of Mn-Ti oxide formation in Si-Mn-Ti deoxidized steel
Mn-Ti oxides in Si-Mn-Ti deoxidized steels after cooling in the furnace were investigated. The composition and morphology of inclusions were analyzed by using FE-SEM with EDS. Mn-Ti oxides were found to be effective sites to induce intragranular ferrite formation. The thermodynamic calculation was employed to interpret the critical condition for Mn-Ti oxide formation. Mn-Ti oxide formation was controlled not only by Mn and Ti content, but also by total oxygen content in steel. When the Mn and Ti contents were around 1.5% and 0.005%–0.01%, respectively, Mn-Ti oxide could form as the total oxygen content was 0.001%–0.002%. The experimental results were in good agreement with thermodynamic calculation results. Also, MnS solubility was examined in Mn-Ti oxide inclusion system. With an increase of MnO content in Mn-Ti oxide. MnS solubility in the oxides increased. MnS precipitation benefited from high MnO content in Mn-Ti oxide.
Key wordsSi-Mn-Ti deoxided steel Mn-Ti oxide MnS intragranular ferrite thermodynamic calculation
Unable to display preview. Download preview PDF.
- Takamura J, Mizoguchi S. Roles of Oxides in Steels Performance [C] //ISIJ. Proc 6th Int Iron and Steel Congr. Nagoya: ISIJ, 1990: 591.Google Scholar
- Mizoguchi S, Takamura J. Control of Oxides as Inoculants [C] //ISIJ. Proc 6th Int Iron and Steel Congr. Nagoya: ISIJ, 1990: 598.Google Scholar
- Sawai T, Wakoh M, Ueshima Y, et al. Effect of Zr on the Precipitation of MnS in Low Carbon Steels [C] //ISIJ. Proc 6th Int Iron and Steel Congr. Nagoya: ISIJ, 1990: 605.Google Scholar
- Ogibayashi S, Yamaguchi K, Hirai M, et al. The Features of Oxides in Ti-Deoxidized Steel [C] //ISIJ. Proc 6th Int Iron and Steel Congr. Nagoya: ISIJ, 1990: 612.Google Scholar
- Kang Youn-Bae. Thermodynamic Studies on Phase Equilibria of MnO-SiO2 Containing Oxide Systems and Their Application to Inclusions Engineering in Steels [D]. Pohang: Pohang University of Science and Technology, 2005.Google Scholar
- Henry Gaye. Inclusion Formation in Steels [C] //Alan W Cramb. The Making, Shaping and Treating of Steel; 11th Edition. Casting Volume. Pittsburgh: The AISE Steel Foundation, 2003: 1.Google Scholar
- Karsrud K. Sulfide Capacities in TiO2 Containing Slags. II—Sulfide Capacities and Activities in MnO-TiO2 Melts at 1500 °C [J]. Scand J Metall, 1984, 13: 265.Google Scholar
- Chao H C, Smith Y Z, Van Vlack L H. The MnO-MnS Phase Diagram [J]. Trans TMS-AIME, 1963, 227: 796.Google Scholar