While increasing energy costs and the necessity to reduce carbon dioxide (CO₂) emissions call for more energy efficient cars, trucks, machines and plants, the steel and stainless steel industries have focused on developing new steel grades with higher strength for lighter constructions, rolling technology supplier SMS Siemag states.

In light of this, a key focus of SMS Siemag is to elaborate mill concepts for the most efficient production of high strength steel and stainless steel.

The general aim of these developments is to find solutions to provide high flexibility in a mill’s production, the company says. For an economical mill design, the work roll diameter is the key design factor, the company stresses.

“Looking at the line load and roll flattening, it becomes obvious that appropriate work roll diameters for 4-high or 6-high stands are too large for an economical production of cold rolled high strength steels,” the company says.   

SMS Siemag took the classic 18-high design and developed it further by the introduction of CVC plus to improve product flatness and by the HS system to control the horizontal forces on the side support rolls. Together with enhanced lubrication, these measures allow the increase of the reduction for each pass. In parallel, process stability and product quality are improved, the company says.

Stainless Steel
SMS Siemag notes that the market for stainless steel is continuously growing, despite the global crises in 2009, adding that in 2008, worldwide, nearly 26-million tonnes of stainless crude steel were produced.

Further, the biggest production is located in Asia (including China) with about 58% of global production, the company adds.

Despite economic turbulences, large stainless steel producers are looking for mill concepts offering high capacity and reduced operation cost to be better positioned in the future.

In light of this, SMS Siemag developed the multipurpose mill, which provides a concept in which it is possible to change between CVC plus 4-high and CVC plus 18-high HS mill during regular roll change.

“This increases the flexibility of the customer and allows for the adjustment of the cold rolling mill according to the material to be rolled, and therefore to be more economically efficient in producing an even wider range of steel grades,” the company emphasises.

SMS Siemag cites several examples in which the company provided cold rolling mills for steel and stainless steel producers, including supply of a high-performance tandem cold mill for fine strip of carbon steel and stainless steel grades for US-based steel producer AK Steel, which is known for its silicon, carbon and stainless steels.

In the mid-1990s, when discussing the new cold rolling facility for the SMS Siemag works in Rockport, in the US, the requirement was to find a solution that allows for producing carbon as well as stainless steel in an economical way and at large quantities.