Study on Carbonitride Precipitating Process in Nb-V Micro-Alloyed Steel

The carbonitrides precipitates in Nb-V micro-alloyed steels were investigated by 3DAP. Much difference in the composition and size of the precipitates were observed. It is proposed that the carbon atoms segregated first at the dislocation or vacancy, and the vanadium and niobium atoms diffused to these sites to form the V-C, V-Nb-C clusters, leading to the formation of (Nb,V)C complex phase. The composition becomes inhomogeneity as the precipitates grow up.