Active Tundish Slag
The role of tundish was originally to function as a steel reservoir after the ladle and a distributor into continuous casting moulds. It was designed to obtain proper steel flow pattern through the tundish and to keep thermal losses inside certain limits. When production of clean steels with high requirements for oxide inclusions was developed by applying sophisticated secondary steelmaking treatments in the ladle the role of tundish became more critical. It became essential to maintain or even to improve the level of the steel cleanliness by minimizing contamination of steel with air, slag or refractory materials between ladle and the casting moulds. According to a novel principle of clean steel production the main function of tundish is to maintain the level of cleanliness attained in the ladle by minimizing harmful contamination of steel with air, slag or refractory materials from ladle to moulds. This could be called a protective or inert tundish practice. As a consequence, the function of tundish slag is a barrier against reoxidation and thermal losses. By reconstructing tundish to a closed chamber with lid, argon gas shrouding and eventual heating system, tundish slag might be even ignored. The concept of active tundish slag aims definitely at improving of steel cleanliness by tailoring a proper tundish slag. In this project active tundish metallurgy was investigated and assessed. Computation of phase diagrams was used as an approach to understand properties and behaviour of tundish slags in casting conditions. Eventual reactions between steel and slag in the tundish were examined by equilibrium calculations. Interfacial phenomena controlling inclusion removal and dissolution into tundish slag were investigated by applying several experimental techniques. Dissolution of alumina and MgO·Al2O3 inclusions into slag were studied by model experiments applying CLSM and DHTT methods. Viscosity of slags was measured by rotating cylinder method at different temperatures. Interfacial tension between steel and slag were measured by drop weight method for several slag/steel systems. The study showed the complexity and multi-disciplinarity in designing slags which can efficiently absorb macro- and micro-inclusions from different steels and at the same time act as protective cover against reoxidation and thermal losses. The final conclusion was that slag optimization is a challenging issue on which favourable metallurgical and thermal properties should be combined with long-lasting effect during sequential casting operation.
active tundish slag inclusion removal interfacial tension wetting inclusion dissolution reoxidation
Lauri Holappa Marko Kekkonen Seppo Louhenkilpi Rene Hagemann Christina Schr(o)der Piotr Scheller
Aalto University School of Chemical Technology, Department of Materials Science and Engineering, PO TU Bergakademie Freiberg, Institute of Iron and Steel Technology, Leipziger Straβe 34 09599 Freiber
国际会议
Ninth International Conference on Molten Slags,Fluxes and Salts(第九届国际熔渣、溶剂与熔盐学术会议 MOLTEN12)
北京
英文
1-14
2012-05-27（万方平台首次上网日期，不代表论文的发表时间）