Niobium in dual phase and trip steels

Low alloyed multi phase steels are subject to extensive research efforts especially with regard to automotive applications due to their attractive combinations of mechanical properties. In this paper the microstructural characteristics differentiating multi phase steels from conventional cold formable steels are highlighted. The processing of dual phase steels and TRIP steels is described in detail and various alloying concepts are reviewed. Special emphasis is laid on the decisive role of niobium with respect to transformation behavior and microstructure development. It is concluded that the addition of niobium can provide a further improvement of the mechanical behavior and thus enlarge the application field of multi phase steels. (AU)