Nov 15 2010
Siemens VAI Metals Technologies will install a new intensive-cooling unit in the Hot-Strip Mill 2 of ThyssenKrupp Steel AG in Duisburg-Beeckerwerth, Germany.
The “Power Cooling” process will enable high- and highest-strength steels to be reliably cooled for a wide range of strip thicknesses. This will enable additional steel types to be efficiently produced with a high degree of precision. The intensive cooling unit is scheduled to commence operation in December 2010.
Example of a Siemens VAI cooling unit in a hot-strip rolling mill.
The intensity of cooling and volume flow in the cooling section must be carefully regulated so that the desired microstructure of the rolled material is achieved with high precision. Contrary to laminar-flow strip-cooling processes, “Power Cooling” technology developed by Siemens VAI allows cooling rates as high as 400 K/s. In particular, the production of high- and highest-strength steels in the upper thickness range of up to one inch requires high cooling rates. Another special feature of the cooling section is the wide range within which the flow volume can be regulated. This enables the strip-cooling process to be precisely and flexibly controlled. “Power Cooling” can achieve heat flow densities of up to 5 MW/m2 – three times higher than the rates achieved with laminar-flow cooling processes. The new cooling system also allows lower flow volumes to be set for a quasi-laminar cooling condition.
A newly developed cross-plant temperature model will also be utilized for the operation of this plant. This model applies a uniform calculation method for the entire finishing mill, through the cooling section and to the coiler. This enables a highly accurate prediction of the start of the phase transition, even if it takes place in the finishing mill. Furthermore, the calculation of the bainitic portions of the structure is also integrated within the model.
The cross-plant temperature model replaces the existing Siemens laminar-flow strip-cooling temperature model, which has been used in the Beeckerwerth Hot-Strip Mill 2 since 2007. It helps the phase transitions to be controlled even more precisely during the cooling of hot-rolled steel strip, thereby increases the flexibility of the rolling mill. Different types of steel can be produced in any sequence, and new types of steel can be added to the production without having to change the software or model parameters.
ThyssenKrupp Steel Europe AG is the leading company for the European carbon-steel activities of the ThyssenKrupp Group, one of the world's largest producers of quality flat-steel. The Hot Strip Mill 2 in Duisburg-Beeckerwerth rolls six million tons of steel per annum, which is one of the highest mill outputs in the world. A rolling modernization program enables ThyssenKrupp Steel Europe to produce a numerous types of modern, high-quality steels for use in the automotive industry and for pipe production.