Transformation of Inclusions in a Complicated‐Deoxidized Heavy Rail Steels During Heating. Issue 9 (2nd June 2020)

• Record Type: Journal Article
• Authors: Zhang, Yuexin; Zhang, Lifeng; Chu, Yanping; Ren, Qiang; Wang, Jujin; Liu, Nan; Chen, Zhiyong; Zhi, Jianguo
• Is Part Of: Steel research international. Volume 91:Issue 9(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-06-02
• Subjects: heavy rail steels -- inclusions -- kinetic models -- thermodynamics -- transformation; Steel -- Periodicals; Steel -- Metallurgy -- Periodicals; 669.142
• DOI: 10.1002/srin.202000120
• Languages: English
• ISSNs: 1611-3683

Abstract

Abstract : The transformation of inclusions in a heavy rail steel during heating is investigated in laboratory experiments. When the steel is heated at 1000–1300 °C, inclusions of CaO–SiO2 –Al2 O3 –MgO are transformed into CaS–MgO·Al2 O3 ones and the contents of CaS and Al2 O3 in inclusions increase, whereas those of CaO and SiO2 decrease. When the steel is heated at 1400 °C, the MgO·Al2 O3 phase in inclusions precipitates, whereas CaS, CaO, and SiO2 still exist, which is caused by the lower thermodynamic driving force at high temperature. With the holding time increasing from 0 to 7 h, the composition of inclusions tends to the equilibrium value which is predicted using Factsage. The transformation phenomenon is validated using thermodynamic analysis and a kinetic model is established to predict the composition of inclusions during heating. The MgO·Al2 O3 phase formed in inclusions in the steel during heating results in an exposure of MgO·Al2 O3 spinel inclusions after rolling, which are rigid and harmful to the performance of steel rails. Abstract : A kinetic model is established to predict the composition of inclusions during heating and the variation in the composition of inclusions with the heating temperature shows a similar trend with the experimental result. As the heating temperature increases from 1000 to 1300 °C, inclusions of CaO–SiO2 –Al2 O3 –MgO are transformed into MgO·Al2 O3 –CaS–(CaO–SiO2 ) ones.