With the improvement of steelmaking technology and the diversification of ladle refining technology, the use environment of the ladle has become more and more harsh due to factors such as increased molten steel temperature, prolonged residence time and vacuum refining environment, which seriously affects the service life and production efficiency of the ladle lining. The causes of damage to the ladle lining are mainly divided into the following three categories:
The online baking temperature of the ladle is about 800~1000℃, while the tapping temperature of the converter and electric furnace ranges from 1600~1700℃, and the maximum temperature difference can reach 900℃. Therefore, the intermittent operation of the ladle and the rapid cooling and heating shock during multiple uses cause thermal stresses to be generated due to temperature changes between the working surface (in direct contact with high-temperature molten steel) and the non-working surface of the lining working layer, or between components with different inherent thermal expansion coefficients in the material, or between the metamorphic layers caused by the penetration of corrosive agents such as slag into the pores inside the refractory material; some lining working layer materials that are free of burning or low-temperature baking undergo mineral phase transformation inside the material during use, resulting in phase change stress. For example, thermal stress and phase change stress exceed their use strength, resulting in spalling damage.
When tapping steel, the molten steel scours the lining at high speed and force, or when refining gas is introduced, the turbulence formed by the intensified movement between the two dispersion systems of gas and molten steel, scouring and wear of the ladle lining, etc. These mechanical stresses cause mechanical damage to the ladle lining.
During the entire ladle service process, due to the long-term contact between the high-temperature molten steel and slag and the ladle lining, the slag and other corrosive agents will continue to penetrate into the ladle lining working layer. The chemical reactions between the oxides (CaO, FeO, Fe₂O₃, MnO, SiO₂, etc.) in the molten steel and slag and the ladle lining are as follows: 312CaO+7Al₂O₃=12CaO·7Al₂O₃FeO+Al₂O₃=FeO·Al₂O₃
2MnO+SiO₂+Al₂O₃=2(MnO)·SiO₂·Al₂O₃ generated by the reaction form chemical erosion and penetration, resulting in deterioration of the working surface, thereby reducing the service life of the ladle lining.