When a very high surface quality is required, it is necessary to use rolls with a fine and perfectly homogeneous microstructure and low inclusion content. This is achieved by using the electro slag remelting (ESR) method. ESR is also used in applications where high stresses are prevalent such as on the work rolls in six-high cold mills.

The first step in electro slag remelting is to manufacture electrodes with the correct target chemical composition. These are produced in our electric steel plant using the same manufacturing process as that used for ingots. Scrap rolls may also be used as electrodes.

Once in place, the electrodes are progressively melted using the heat generated by passing a strong alternating current between the electrode and the solidified ingot. To refine the steel, the metal droplets pass through electro-conductive slag before solidifying in a water-cooled ingot mould. Thus the ingot is formed.