Continuous Annealing Lines
High-speed lines to process AHSS for automotive applications
The process of annealing steel strip continuously allows several indisputable quality advantages when compared to the batch process – in particular, uniformity of heating and cooling. Nowadays, continuous annealing is the only process that allows a very fast cooling rate for the steel after recrystallization.
This high cooling rate is essential, at least in order to produce advanced high-strength steels without resorting to exotic grades and expensive steel chemistries, and it is the only option when final tensile strengths in excess of 1,000 MPa are required.
As a contrasting argument, the production of very soft grade still nowadays remains cheaper through a batch processing route, especially for black plate, though with inferior but acceptable mechanical properties for uniformity.
Compared to the batch process, continuous annealing combines in one step the degreasing, annealing, and skin-passing steps, thus avoiding expensive coil transfer from one process to the next.
Excellent annealing results, in the automotive sector especially, are achieved thanks to fully automated temperature control, specific annealing cycles and rapid cooling system.