Vanadium - Transforming Possibilities

Development and Applications of V-N Microalloyed Steels in China

Abstract:

This paper reviews the recent development of V-N microalloying technologies and its applications in HSLA steels in China. Enhanced-nitrogen in V-containing steels promotes precipitation of fine V(C,N) particles, and improves markedly precipitation strengthening effectiveness of V(C,N), therefore, there is a significant saving of V addition in a given strength requirement. V-N microalloying can be used effectively for ferrite grain refinement as well by the nucleation of intra-granular ferrite promoted by VN precipitates in Austenite in V-N steels. Compared with Nb-Ti steels, V-Ti-N steels show superior weldability under large heat input welding due to the ideal ferrite-based microstructure with relatively fine ferrite grain size in CGHAZ. V-N microalloying process is a cost-effective way which has been widely used for high strength rebars, section steels, forging steels, seamless pipes, and CSP strip steels in China.

Keywords:

 V-N microalloyed steels, precipitation strengthening, intra-granular ferrite nucleation, ferrite grain refinement, weldability