The VAI galvannealing controller: Technology, experience, benefits

In response to the demands of the automotive industry the steel producer Voest-Alpine Stahl Linz GmbH (VA Stahl) and the engineering and plant-building company Voest-Alpine Industrieanlagenbau GmbH (VAI), both of Linz/Austria, have jointly developed a new closed-loop galvannealing process controller which allows for the on-line control of the iron content and surface quality of galvannealed steel strip. The controlling loop and the operational results of the application are described. The main benefits are the continuous control of surface quality and a major reduction in off-tolerance strip lengths resulting from varying operation conditions. Yield improvement of about 2% were achieved.