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High quality steels such as the ultra-low carbon steels microalloyed with titanium or the Al-killed steels (untreated or treated with pure calcium) can contain MgO/Ca inclusions with the risk of enhancing nozzle clogging or the occurrence of superficial or internal defects on rolled products. The objective of this research was to study the origin and the main sources of these complex inclusions and to define working conditions to avoid them. For the production of low carbon Al-killed steels at the SIDMAR steelshop considered as a reference, a synthetic ladle top slag composed of a mixture of CaO (90%) and CaF(2) (10%) proved to be the most accurate for entrapping deoxidation inclusions and for achieving a very high cleanliness level. The residual inclusions are mainly composed of Al(2)O(3) without the presence of MgO or CaO in the final products. A progressive improvement of the refining conditions of Ca treated steels has allowed a better control of the inclusion composition. The MgO level in the aluminate inclusions has been substantially decreased and doesn't seem to exert a significant role on the properties and on the castability of the steel.

Additional information

Authors: MARIQUE C, Centre de recherches métallurgiques, Liège (BE);BUYDENS J-M, Centre de recherches métallurgiques, Liège (BE)
Bibliographic Reference: EUR 16690 FR (1997) 66pp., FS, ECU 11.50
Availability: Available from the (2)
ISBN: ISBN 92-828-0257-4
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