Get an insight into our special open coil annealing process, which produces cold rolled steel strip with different degrees of hardness within the strip cross-section. The process essentially consists of three steps:
1. Inserting wire into the coil
The space between the layers of strip created by the wire ensures that the water vapor can easily flow through during subsequent annealing.
2. Bell annealing of the steel strip
During annealing, steam is fed in to decarburize the material surface, making it soft, while the material core remains hard.
3. Bend testing in quality assurance
After open coil annealing and bainitic hardening and tempering, the steel strip can be bent by more than 90 degrees without cracking.