Fluid Flow and Steel Cleanliness in Argon-stirred Ladles
The increasing demands for high cleanliness steel products require the continuous improvement of steelmaking refining and casting techniques to ensure the low content of inclusions in steel. Clean steel requires that the size distribution, morphology, amount and composition of non-metallic oxide inclusions should be under control to a certain level [1-3] . The fluid flow patterns in the vessels affect the motion and the removal of inclusions. Argon bubbling and stirring is one of the most popular steel refining methods [2, 4-8]. Argon bubbling favors the mixing of the composition and temperature of molten steel,and promotes the removal of inclusions. Many studies have investigated the mixing of ladles stirred with argon gas. [2, 4-8] Manda investigated the mixing phenomena in ladles stirred by argon gas injected with dual porous plugs located diametrically opposite at half radius. Zhang simulated the fluid flow in ladles stirred by one or two gas jets, indicating that the distance between the two nozzles had a major effect on the fluid flow.  Non-metallic inclusions originate from many sources , including: 1) Deoxidation products generated by the reaction between dissolved oxygen and the added deoxidant, such as aluminum. For example alumina inclusions cause the majority of indigenous inclusions in LCAK steel. 2)Reoxidation products, generated i) when Al remaining in the liquid steel is oxidized by FeO, MnO, SiO2 and other oxides in the slag and refractory linings, or ii) by exposure to the atmosphere; 3) Slag entrained into the molten steel, generating inclusions especially when transferring between steelmaking vessels. The formed liquid inclusions are usually spherical; 4) Exogenous inclusions from other sources, including loose dirt, broken refractory brickwork and ceramic lining particles; 5) Chemical reactions, producing oxides from inclusion modification when Ca treatment is improperly performed.
S. Yang et al., "Fluid Flow and Steel Cleanliness in Argon-stirred Ladles," AISTech Conference Proceedings, Association for Iron & Steel Technology (AIST), Jan 2009.
2009 AISTech Conference Proceedings
Materials Science and Engineering
Article - Journal
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