Microalloying with Vanadium for Improved Cold Rolled TRIP Steels
Flat carbon steel manufacturers are currently developing new Transformation Induced Plasticity (TRIP) steels as a response to strong demands for vehicle lightening and security reinforcement from the automobile sector［1］. These advanced grades exhibit a very favourable compromise between strength and ductility compared to conventional steels and can therefore be produced in lighter, thinner gauge strips with equivalent functional properties. The excellent mechanical properties of TRIP steels are attributed to the high strain hardening coefficient generated by the progressive transformation of metastable retained austenite to martensite during plastic deformation. In this paper we will discuss the improvements in cold strip properties that can be obtained using vanadium microalloying in these steels. By choosing an appropriate composition and thermomechanical process path, a high fraction of the added vanadium can be made to precipitate in ferrite during the continuous annealing step, providing a large strengthening effect. This gain in strength is obtained without any significant loss of ductility as, apart from a useful grain refining effect, the presence of vanadium does not significantly modify the original TRIP microstructure.
vanadium, TRIP steel.
C. Scott, F. Perrard, P. Barges
Automotive Research Center, Arcelor Research S.A., Voie Romaine, 57283 Maizières-lès-Metz
Application Technologies of Vanadium in Flat-rolled Steels –Vanitec Symposium, Suzhou, China, Oct. 2005, pp.13-25