New Trends and Technologies in Thin-Slab Direct Rolling: Improved Microstructure & Mechanical Behavior

Abstract:

The use of CSP^® thin slab casting followed by direct thermomechanical rolling is well placed for the production of low-carbon Nb microalloyed steels. In this process thin slabs of between 48 and 90 mm thickness are cast and directly hot rolled to hot strip typically between 1 and 12 mm thick. To obtain optimum strength and toughness property combinations in a direct rolling process, hot rolling has to compact the dendritic as-cast microstructure and to achieve a fine-grained microstructure. This affords a two-stage rolling strategy with start rolling above the recrystallization stop temperature and finish rolling in the non-recrystallization temperature range. Temperature and deformation in the first stand should be as high as possible in order to delete the initial as-cast microstructure by complete recrystallization. Based on these considerations, SMS Siemag further developed the CSP^® concept including features allowing isothermal rolling in the first stands of the finishing mill. The present contribution gives the results of a laboratory study of this innovative approach. The report concludes with resulting new plant configurations for improved high strength and API linepipe grade production.

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 2752-2757
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.2752
• Online since: January 2012
• Authors: Christian Klinkenberg, C. Bilgen, J.M. Rodriguez-Ibabe, Beatriz López, Pello Uranga
• Keywords: API Grade, CSP^®, HSLA, Microalloying, Microstructure, Niobium, Recrystallization, Thermo-Mechanical Rolling, Thin Slab Casting

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