Comparação da estampabilidade de chapas de aço inoxidável ferrítico estabilizado ao nióbio obtidas através de duas rotas de fabricação

Abstract

Stainless steels are important due to the synergy among their different properties. One can mention some of them, such as the excellent resistance to the action of many agressive environments and also the mechanical properties, that allow their use in many applications. Basically half of the stainless steels are supplied as cold rolled coils, which are mainly used in sheet forming processes. In order to improve the ferritic stainless steels sheet formability Acesita developed in thenineties a new ferritic steel called internally ACE P430E. The niobium addition, along with a rigorous chemical balance and controlled hot and cold processes have enabled the production of a material with better formability than the conventional non stabilized ferritic grades.In the end of 2002 a different processing route for this material was initiated. Whereas until then the material was produced with only one cold rolling step (direct reduction), two cold rolling steps were adopted, with an intermediate annealing (reduction with an intermediate annealing), aiming at the elimination of some typical problems present in the material produced by direct reduction, and the improvement of the material formability. The forming behaviour of the niobium stabilized ferritic stainless steel produced with intermediate annealing is superior to the same steel produced by direct reduction. Another positive aspect of this new production route is its lower ridging level, leading to therecommendation of the product to situations where the presence of ridging is unacceptable.