Comparative Study of Microstructure, Texture, and Formability Between 11CrTi and 11CrTi+Nb ASTM 409 Ferritic Stainless Steel

posted on 05.12.2017 by Ricardo José Gonçalves Costa, Daniella Gomes Rodrigues, Hélio José Batista Alves, Tarcísio Reis de Oliveira, Berenice Mendonça Gonzalez

Stabilization of ferritic stainless steel ASTM 409, for use in automobile exhaust systems, is increasingly in demand, due to higher exhaust gas temperatures. Ti is one of the most commonly used elements. However, high concentrations cause problems during steel casting; however, stabilization with Ti and Nb represents a good alternative. The present study aims to investigate the effect of adding Nb on the microstructure, texture, and forming properties of Ti-stabilized ferritic steels. The results demonstrated that Nb-addition leads to a more deformed microstructure after hot rolling with the strongest {110}〈001〉 Goss component. In the deformed state, the steels displayed the α-fiber, but 11CrTi+Nb steel showed a more intense γ-fiber. After annealing, Nb-addition led to an increase in the γ-fiber and in average normal coefficient of anisotropy (R). Thus, it was demonstrated that the dual stabilization (Ti+Nb) of the ferritic steel was responsible for improving the recrystallization texture and forming proprieties.