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voestalpine Stahl and Siemens Set World Casting Record

07/24/2007 - voestalpine Stahl casts 355-mm thick and 1600-mm wide slabs on a caster recently upgraded by Siemens Metals Technologies, earning the distinction of producing the thickest slab ever cast on a bow-type caster with straight mold.

voestalpine Stahl GmbH recently cast 355-mm thick and 1600-mm wide slabs on one of the company's slab casters in Linz, Austria. The caster was recently upgraded and recommissioned by Siemens Metals Technologies.
 
The caster, previously supplied by Siemens VAI, is a bow-type slab caster with a machine radius of 10 meters. The ultra-thick slabs were cast using the DynaGap SoftReduction technology packages to ensure the highest possible internal quality. The casting operation also employed the newly developed “machine-protection mode,” which supervises casting operations for an optimum casting speed.
 
voestalpine Stahl produces approximately 5.5 million tonnes of carbon and alloyed steel slabs per year, all of which are cast on one of four slab casters. For one downstream product application, it was necessary to roll thicker plates in the plate mill while still meeting quality requirements. Thicker slabs were required to allow the application of the minimum number of rolling passes necessary to ensure that the targeted internal steel structure and steel homogeneity for the plates.
 
Siemens Metals Technologies upgraded the existing No. 5 Continuous Caster, which previously produced slabs at a maximum thickness of 285 mm, to make it capable of casting 355-mm thick slabs. Siemens supplied a new mold and bender, and optimized the casting process parameters to facilitate the production of ultra-thick slabs that could satisfy the highest demands for slab surface and internal quality.
 
For the metallurgical length of the No. 5 Continuous Caster (i.e., the distance from the liquid steel meniscus in the mold to the final point of steel solidification), it is vital that the casting speed be maintained within a defined casting-speed window. If the casting speed is too high, the metallurgical length may extend beyond the strand-containment system, resulting in strand deformation. If the casting speed is too slow, the slab solidifies too quickly and cannot be properly straightened without potential equipment damage.
 
For the upgrade, Siemens installed a number of technological packages that were key to ensuring reliable casting operations, production flexibility, and the casting of high-quality slabs. These included:
  • DynaFlex for flexible adjustment of mold-oscillation parameters
  • MoldExpert for online automatic breakout prediction and strand-shell friction monitoring
  • LevCon for automatic mold-level control
  • DynaWidth* for online mold-width/slab-width adjustment
  • SmartSegments* with DynaGap SoftReduction*, a fully automatic roll-gap control system allowing dynamic soft reduction to minimize centerline segregation and improve internal strand quality
  • Level 2 Dynacs*, a secondary-cooling system.
 
Siemens completed the modification work within five days—one day ahead of schedule. The caster was successfully started up and slabs were cast at a speed of 0.7 meters per minute.
 
*Dynacs, DynaWidth, SmartSegment and DynaGap SoftReduction are registered trademarks of Siemens AG, its subsidiaries or affiliated companies.
 
Metals Technologies (MT), a division of the Siemens Industrial Solutions and Services (I&S) Group, is one of the world's leading engineering and plant-building companies for the iron and steel industry as well as for the flat-rolling sector of the aluminum industry and for open-cast mining. MT, which was created from the integration of Voest-Alpine Industrieanlagenbau, Austria, plus the electrical engineering product business and automation solutions of Siemens, provides a comprehensive range of supplies and services for all related technological processes and integrated automation solutions for the entire life-cycle of metallurgical plants.
 
The Siemens Industrial Solutions and Services Group (I&S) is the integrator of systems and solutions for industrial and infrastructure facilities and global service provider for the plant and projects business covering planning, installation, operation and the entire life cycle. I&S uses its own products and systems and process technologies in order to enhance productivity and improve competitiveness of companies in the sectors of metallurgy, water treatment, pulp and paper, oil and gas, marine engineering, open-cast mining, airport logistics, postal automation, intelligent traffic systems and industrial services. In fiscal 2006 (to September 30) I&S employed a total of 36,200 people worldwide and achieved total sales of EUR 8.819 billion, according to U.S. GAAP.