RHI AG (Wien, Austria):

Thomas M., Head of Marketing and Technology Tundish Dept.
Kirschner M., Dr., Secondary Metallurgy Dept., marcus.kirschen@rhi-ag.com
McIlveney G., Head of Marketing Linings Europe Dept., Steel Division

RHI AG (Leoben, Austria):

Hackl G., Head of Simulation Dept., Technology Center

The demand for clean steel production is ever increasing, principally because steel for more sophisticated processing routes and applications requires smaller-sized oxide inclusions. Steel cleanliness requirements for various steel grades are analyzed. Sources of nonmetallic inclusions and water model for visualization of the homogeneous distribution of small gas bubbles from a porous purging plug with low gas purging rate (soft bubbling) are observed. Ladle shroud to protect the melt against reoxidation during transfer from the ladle to the tundish is shown as well as argon shielding ZAAG system used to reduce air ingress during shrouded transfer between the ladle and the tundish. Influence of argon rinsing in the tundish on the number of defects in cast steel at different casting speeds is assessed. Modifying inclusion morphology, composition, and size is employed to produce lower melting point species and harmless characteristics during rolling. In addition, minimizing residual impurities including sulphur, phosphorous, hydrogen, nitrogen, and carbon is also targeted during clean steel production. RHI provides a range of refractory solutions to enhance steel cleanliness during the entire steelmaking process. The example of a microscopic inclusion consisting of spinel and Caaluminate in a high-strength steel is presented. In addition, various modelling capabilities are available to optimize tundish efficiency during clean steel production. Measured and CFD-simulated RTD in a 16-t single strand tundish water model and calculated RTD curves for a 30-t four-strand tundish without furniture (original) and with a Tunflow and weir-dam combination (optimized) is presented.

1. Wünnenberg, K.; Cappel, J.: Measures to Improve Oxide Cleanness in Continuous Casting, Proc. AISTech 2009 Conference, 4.–7. Mai 2009, St. Louis, USA.
2. Zhang, L.; Thomas, B. G.: ISIJ Intern. 43 (2003) Nr. 3, S. 271/91.
3. Badr, K.; Tomas, M.; Kirschen, M.; McIlveney, G.: RHI Bulletin (2011) Nr. 1, S. 43/50.
4. Sahai, Y.; Emi, T.: Tundish Technology for Clean Steel Production, World Scientific Publishing, Singapur, Singapur, 2007.
5. Odenthal, H.; Javurek, M.; Kirschen, M.: steel res. intern. 80 (2009) Nr. 4, S. 264/74.
6. Sahai, Y.; Emi, T.: ISIJ Intern. 36 (1996) Nr. 9, S. 1166/73.
7. Kaufmann, B.; Niedermayr, A.; Sattler, H.; Preuer, A.: steel res. 64 (1993) Nr. 4, S. 203/9.
8. Odenthal, H.; Javurek, M.; Kirschen, M.; Vogl, J.: steel res. intern. 81 (2010) Nr. 7, S. 529/41.
9. Kirschen M.; Lanzenberger, R.; Petritz B.; Prietl, T.: Optimum lining performance for particular process slags supported by thermochemical modelling, Proc. AISTech 2011 Conference, 2.–5. Mai 2011, Indianapolis, USA, S. 1289/98.
10. Bale, C.; Chartrand, P.; Degterov, S.; Eriksson, G.; Hack, K.; Ben Mahfoud, R.; Melançon, J.; Pelton, A.; Petersen, S.: Calpha 26 (2002) Nr. 2, S. 189/228.