Annealing and Pickling Line (APL) for Silicon Steel Strip
The hot rolled strips (NGO and GO) are initially annealed in a continuous process to eliminate brittleness prior to cold rolling and to modify the microstructure. The annealing process is followed by a controlled cooling stage with a cooling rate which may range from 5 to 80 K/s depending on the steel grade required.
Tenova, with its over 40 years of experience, is the only company with the competence and knowledge, of the entire multi-stage thermal process chain, which is required for the production of grain-oriented electrical steel strip.
The hot rolled strips (NGO and GO) are initially annealed in a continuous process to eliminate brittleness prior to cold rolling and to modify the microstructure. The annealing process is followed by a controlled cooling stage with a cooling rate which may range from 5 to 80 K/s depending on the steel grade required. This process is usually carried out in a nitrogen atmosphere to protect the strip surface.
Typical line basic data:
- Material: GO & NGO hot & cold rolled strip (Si 3.5 %)
- Yearly capacity: 100 - 400 kt/y
- Process speed: 40 - 85 m/min
Terminal Equipment and Process Section with specialties like: High turbulence shallow pickling tanks Special multiple cascade rinsing section with controlled acidity for high surface quality Side trimmer with rotating turrets.
Value for Money
- Key technology for the processing of silicon steel
- Highest process accuracy and repeatability guarantees stable magnetic properties
- Modern heating technology
- Heat and energy recovery
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Processing Lines for Silicon Steel
Annealing and Coating Line (ACL) for Silicon Steel StripNon-grain-oriented strip is annealed in a radiant tube furnace using a continuous process after cold rolling to ensure recrystallization and controlled grain growth. Top-quality steel requires strip temperatures above 1100°C and a very dry atmosphere with a high hydrogen content. This is followed by controlled cooling to obtain an extremely flat strip.
Decarburizing and Coating Line (DCL) for Silicon Steel StripCold rolled GO Si steel strip is annealed in a continuous process line for primary recrystallization and decarburization. After the steel strip has passed through the DCL furnace, it is coated with magnesium oxide and then dried.
Flattening and Coating Line (FCL) for Silicon Steel StripFor the final heat treatment process the transformer strip is coated with insulating varnish in an in-line process and then dried in an indirectly heated furnace. The steel strip is heated further in a radiant tube furnace with a controlled atmosphere and then straightened using the integrated hot stretching equipment. This stage is followed by a slow cooling process.
Lamination Furnace for Semi-Finished Silicon Steel StripSemi-finished electrical steel requires an annealing process with recrystallizing, decarburizing and blueing. The punched laminations are continuously annealed in a roller hearth furnace or for smaller capacity in a pusher type furnace.