Transformation of Inclusions in a Complicated‐Deoxidized Heavy Rail Steels During Heating

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–Al2O3–MgO are transformed into CaS–MgO·Al2O3 ones and the contents of CaS and Al2O3 in inclusions increase, whereas those of CaO and SiO2 decrease. When the steel is heated at 1400 °C, the MgO·Al2O3 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·Al2O3 phase formed in inclusions in the steel during heating results in an exposure of MgO·Al2O3 spinel inclusions after rolling, which are rigid and harmful to the performance of steel rails.

Machine Learning‐Aided Process Design: Modeling and Prediction of Transformation Temperature for Pearlitic Steel

“…Due to the prominent performance in mechanical properties and wear resistance, pearlitic types of steels have generated wide attentions in various engineering industries, especially in railway applications. [1][2][3][4][5][6] With the increasing demand for civil transport, thus, the current focus extremely heightened the urgent need for better comprehensive performance. [7] As known, the properties of steels mainly depend on alloying elements and their metallographic microstructures, which can be improved via adjusting the heat treatment.…”

Effect of Total Calcium in Heavy Rail Steels on the Transformation of Inclusions during Heat Treatment at 1473 K

“…[16][17][18] Experimental studies concerning the heating temperature and holding time were performed on the transformation of inclusions in a solid heavy rail steel. [19] Inclusions transformed from CaO-SiO 2 -Al 2 O 3 -MgO to CaS-MgO•Al 2 O 3 . However, for complex inclusions, the effect of steel composition on the transformation of inclusions during heat treatment of the steel has rarely been studied.The current article focused on the transformation of complex inclusions in a heavy rail steel during the heat treatment at 1473 K. The effect of total calcium (T.Ca) content in the heavy rail steel on inclusion transformation was studied by laboratory experiments and theoretical calculation.…”

“…[16][17][18] Experimental studies concerning the heating temperature and holding time were performed on the transformation of inclusions in a solid heavy rail steel. [19] Inclusions transformed from CaO-SiO 2 -Al 2 O 3 -MgO to CaS-MgO•Al 2 O 3 . However, for complex inclusions, the effect of steel composition on the transformation of inclusions during heat treatment of the steel has rarely been studied.…”