Ultra-Thick Slab Casting at CC5 at Voestalpine Linz/Austria

摘要

Voestalpine CC5 caster went into operation in 1997. From 2000 to 2001 the segments were equipped with SIMETAL CIS DynaGap SoftReduction? in order to perform dynamic soft reduction. The 10 m conventional bow type caster with straight mold and liquid core bending and straightening was originally designed for a thickness range of 210 to 285 mm. In 2006 Siemens VAI was awarded to revamp voestalpine CC5 caster in order to increase the maximum slab thickness to 355 mm.Modifications of the tundish cars, the segment support structure and the torch cutting machine were necessary due to the increased casting thickness. A new mold, new bender and new dummy bar head for 355 mm thickness were designed and supplied by Siemens VAI.The process parameters had to be adapted in order to achieve optimum surface and internal quality. Since metallurgical length was not changed, the maximum casting speed is limited by the containment length. The minimum casting speed is limited by maximum admissible straightening forces of the equipment, since the equipment was design for straightening of 285 mm thickness and no modifications were done in the straightening part.The revamping was done in five days in June 2007 (one day less than planned). Already the first cast was carried out with pipe grade steel at a casting speed of 0.7 m/min at a width of 1600 mm.Quality examinations of these and subsequently produced slabs showed excellent results. Only small bulging on the narrow faces occurred. Surface and internal quality of the slabs were excellent. Thanks to SIMETAL CIS DynaGap SoftReduction no internal cracks and almost no centre segregation have been observed.