Investigation of V–N Micro-alloying Using Nitrogen Bottom Blowing

Herein, a novel method of V–N micro-alloying was developed by adding ferrovanadium and nitrogen bottom blowing. For comparison, melting experiments were carried out by directly adding ferrovanadium nitride. Results indicate that nitrogen content increases rapidly and can reach the actual production level via nitrogen bottom blowing. TEM observations show that carbonitrides precipitate along the dislocation line, on the boundary of cementite and ferrite–cementite, and the ferrite grain boundary. Meanwhile, higher the nitrogen content in the steel, more the precipitates and higher dispersion will form, which indicates that addition of ferrovanadium first is better than blowing nitrogen first. Furthermore, the size, distribution and dispersion of carbonitrides obtained via the method of firstly adding ferrovanadium are comparable with that of directly adding ferrovanadium nitride. The results reveal that it is feasible to realize V–N micro-alloying by adding ferrovanadium and nitrogen bottom blowing.