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Cold Rolling of strips causes non homogeneous variation in metallurgical characteristic of steel. For tempering process, coils shall go to heat treatment line.
The annealing plant which can use a high concentration of H2 gas operates the most improved system in the world which reduces the heat treatment duration while improving the product quality.
Annealing process consists of 10 stages as below:
1- Making the Charge
2- Set Inner Cover
3-Cold Leakage test
4- Nitrogen purge
5- Hydrogen Purge
7- Hot Leakage test
9- Hydrogen Discharge
10- Final Cooling
- Work base
The work-base is designed to support up to 128 t gross weight of cold rolled steel strip coils and intermediate convector plates.
- Inner Cover
The inner cover has to separate the charge from the combustion chamber and to transfer the energy of the flue gas into the hydrogen atmosphere.
- Intermediate Convector Plates
The convector plates are designed to optimize gas flow between the coils and thus to achieve shortest possible heating and cooling times.
- 3-Arm Grip Tong
For shifting inner covers and convector plates round
- Heating Bell
The heating bell is designed to heat up the steel strip coils within the shortest possible time to achieve the required quality of the annealed product.
- Cooling Bell
The air-mass flow / water spray cooling bell is designed to cool the charge at the beginning with 2 radial blowers down to a certain temperature below 380°C before the water spray cooling starts.
- Valve Stand
It is the duty of the valve stand to supply all necessary utilities to the work base and to provide the basic information about the utility consumption.
- Hydraulic Power Unit
- N2/H2 Pressure Reduce Station
To control the Nitrogen and Hydrogen flow rate during heat treatment.
In fact Full-hard coils coming out of the cold rolling mills or Electrolytic Cleaning Line are taken into heat treatment and regain their original mechanical characteristics. All the stress is removed during this process and there may be some deformations on the strip. In order to remove these deformations, the annealed coils are processed at the Skin pass mill.