Nb-V-Ti和V-Ti微合金钢中碳氮化物的回溶行为

DISSOLVING BEHAVIORS OF CARBONITRIDES IN Nb-V-Ti AND V-Ti MICROALLOYING STEELS

采用TEM和EDX技术,研究了低碳微合金钢中Nb,V,Ti的碳氮化物在不同温度保温后的回溶行为．结果表明,Nb-V-Ti微合金钢中存在尺寸明显不同的两类析出,较大的析出颗粒平均尺寸在80nm以上,其心部为(Nb,V,Ti) (C,N),而边部为(Nb,Ti)(C,N),较小的析出颗粒平均尺寸在20nm以下,其类型为(Nb,Ti)(C,N)．两类析出物中Nb/Ti原子比均随回溶温度的升高而减小．V-Ti微合金钢中,Ti的存在对V的回溶具有拖曳作用,提高了V的碳氮化物的热稳定性．Nb-V-Ti微合金钢中,由于Nb,V,Ti之间综合作用,使得析出相中V具有更高的热稳定性．

The dissolving behavior of Nb, V and Ti carbonitrides precipitated in low carbon microalloying steel during isothermal holding at different temperatures were studied by TEM and EDX. The precipitates can be obviously classified into two kinds by their size. The average dimension of the bigger precipitates is over 80 nm, and that of the smaller precipitates is below 20 nm. EDX showed that the bigger precipitates are composed of （Nb, V, Wi） （C, N） in core and （Nb, Wi） （C, N） near edge. With holding temperature increasing, the atomic ratios of Nb/Ti in the two kinds of precipitates decreased. With Ti added to V-containing steel, V will delay dissolving which makes the precipitates exhibit good thermostability in V-Ti microalloyed steel. In Nb-V-Ti microalloyed steel, the strong interaction between Nb, V and Ti further enhances thermostability of V in the precipitates.