Abstract
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.
Highlights
Stainless steels are increasingly gaining ground in the market, due to their versatility, performance, and resistance to corrosion
As can be observed by the Grain Orientation Spread (GOS) map (Fig. 1b), the recovered grains are predominant in the center region and recrystallized grains are in the surface region of the sheet
DNb = %Nb - 7.74 x 0.7 %C Dual stabilized steels (2). These results show that 11CrTi+Nb steel has a higher amount of niobium in a solid solution than does 11CrTi steel
Summary
Stainless steels are increasingly gaining ground in the market, due to their versatility, performance, and resistance to corrosion. The Ti-stabilized ferritic stainless steel, ASTM 409, was developed over 30 years ago for use in automotive exhaust systems, where it is widely used today[1,2]. New designs of exhaust systems have been developed, increasing the service temperature in order to improve the performance of the catalytic converter. Higher concentrations of stabilizing elements in the steel are required, to prevent the possibility of sensitization occurrence in the heat affected zone of the welded joint[4,5]. This prevents the material from exhibiting failures resulting from intergranular corrosion[6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
