In Oxelösund, steel is produced in an integrated process extending from iron raw material to finished plate. The metallurgy is based on ore, and the ore supplied consists entirely of pellets. Together with coke from the company’s own coking mill, represent the raw materials for the production of raw iron. In addition, lime is added as slag former to remove the impurities from the molten iron. The molten iron is at a temperature of about 1400ºC and is transported to the steelworks in “torpedo cars”.

The steelworks

In the steelworks, the iron is refined into steel in a large LD converter (steel furnace). Oxygen is blown into the melt, which reduces the carbon content from around 4% to below 0.1%. Alloying elements are then added to the melt in order to achieve the right quality and the required type of plate material. On tapping, the temperature of the molten steel is around 1700ºC. In order to improve its properties further, the steel is often treated in an injection plant or by vacuum degassing in a ladle furnace. All steel is then continuously cast into slabs in two modern continuous casting machines. The annual slab production capacity is around 1.6 million tonnes. Some of the slabs are used for in-house production of heavy plate, while others are shipped to SSAB Tunnplåt in Borlänge.

>The rolling mill

Our new rolling mill produces heavy plate from slabs of various sizes and grades. The four-high rolling mill is one of the world’s most powerful and can apply a force of 10 000 tonnes when rolling the plate. The mill is the first European heavy plate rolling mill to be equipped with the Continuous Variable Crown (CVC) control system that allows for effective control of the thickness profile and flatness of the plate. After rolling, the plate may be up to 60 metres long and pass through flying shears in which the plate is cut to the required lengths. To achieve high strength and wear resistance, combined with improved weldability and workability properties, the plates are heat treated and/or hardened after welding.