ArcelorMittal, France

Drever furnace in an annealing and coating line

The new annealing and coating line installed at ArcelorMittal St-Chély d`Apcher, France, processed its first coil in March 2013. Preceding this event was excellent preparation by all participants, which ensured commissioning within just a few weeks. It took only one month after the furnace had dried out for the plant to reach nominal production rate.

The line drastically increases our customer's production capacity for high-grade non-grain-oriented electrical steel strip (NGO). Included among the products the furnace processes is iCAReTM. This is a material newly developed by ArcelorMittal which helps automakers create eco-friendly mobility solutions for a greener world.

First up is the annealing and coating line. It's responsible for adjusting the internal microstructure of the electrical steel strip during the annealing process. Next, an insulating layer is applied to the material. Then inductors and electrical heating elements in the horizontal annealing furnace heat the material to 1,100°C. There is a nitrogen- hydrogen atmosphere in the furnace which the operator can set

to a hydrogen content of up to 100 %. This reducing atmosphere helps achieve a particularly oxide-free and clean strip surface. That's important for high-quality material grades. Furthermore, careful and slow cooling of the material improves the microstructure. To achieve the best results, the strip is cooled down at a very accurate cooling rate first in the slow-cooling section, then in the quick-cooling section. Working with high annealing temperatures and hydrogen contents in the furnace, ArcelorMittal achieved outstanding material properties right from the start. What's especially impressive is that the core losses already match those attained by the world's top producers.

Main technical data

Steel grades: NGO
Strip width: 800 mm - 1,350 mm
Strip thickness: 0.18 - 1.5 mm
Process speed: 100 m/min
Capacity: 180,000 tpy

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