SMS Siemag AG (Hilchenbach, Germany):

Krämer S., Head of Hot Rolling Mills Dept.

SMS Siemag AG (Düsseldorf, Germany):

Sprock A., Dr., Referent for Technical Development, e-mail: august.sprock@sms-siemag.com
Hassel Ch., Dr., Central Development Dept.

The demands made on hot-rolled materials have become considerably more stringent over the last few years. On the one hand, models are needed that can provide quantitative statements on the microstructure and thus enable the mechanical properties to be ascertained. On the other hand, for the mechanical equipment of the cooling section, the above properties indicate a heightened demand for water, which needs to be made available in accordance with the required cooling rate. This paper will present improved mechanical equipment, the description of material behaviour in the form of a model and the necessary cooling strategies, with a view to enabling the production of materials which can satisfy future requirements. Resource-effi cient laminar cooling for a hot strip mill at Svenskt Stål (SSAB) in Sweden is displayed and illustration of the cooling rate (CR) as a function of the thickness provided by various operators is presented. Schematic representation of the influence of the cooling rate (CR) and the coiling temperature on the microstructure is analyzed. Attainable cooling rates of diff erent SMS cooling systems for a strip thickness d = 20 mm with T_Water = 35 °C are observed and comparison of a calculated CCT diagram and an experimentally determined CCT diagram for material Ck15 are considered. Progression of Gibbs energy for pure iron and of total enthalpy as a function of the temperature for Ck15 is concluded.

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