Interaction between Steel and Distinct Gunning Materials in the Tundish

摘要

Gunning materials are used as a dispensable protective layer to extend the tundish life. Their use however, affects the steel cleanliness by introducing steel reoxidation and exogenous inclusions. In the present work, the interaction between molten steel and three types of refractory, i.e. MgO, Al_2O_3, and MgO + 2MgO·SiO_2 based gunning materials (GM) have been investigated. Compared to MgO and MgO + 2MgO·SiO_2 GM, the Al_2O_3 GM exhibited better infiltration resistance to molten steel. The two phase MgO + 2MgO·SiO_2 GM was found to be less prone to steel infiltration than single-phase MgO GM. The compositional evolution of steel influenced by gunning material was experimentally measured and also predicted with thermo-dynamic equilibrium calculations. The steel cleanliness in terms of inclusion size, number density, area fraction and morphology was measured and evaluated. Although large Al_2O_3/AlTiO_x inclusions were formed through the erosion of Al_2O_3 GM, the use of Al_2O_3 GM resulted in an improved steel cleanliness due to its lower content of reducible compounds compared to that of MgO and MgO + 2MgO·SiO_2 GM.