含铌钼钢中微合金碳氮化物沉淀析出及其强化机制

Precipitation of microalloyed carbonitride and its strengthening mechanism in low carbon steels containing Nb and Mo

利用物理化学相分析法、透射电镜、能谱分析和X射线衍射分析了两种热轧态的含铌钼低碳钢中微合金碳氮化物析出相的成分、形貌以及粒度分布等特征,结果表明,含铌钼低碳钢中钼可与铌一起析出,形成具有NaCl型面心立方结构的碳氮化铌钼析出相,且0.081Nb-0.14Mo钢和0.17Nb-0.12Mo钢的MC析出相中钼与铌的原子比分别为0.41和0.22。在这两种钢的MC析出相中小于10nm的碳氮化铌钼的质量分数分别为58.4%和66.1%,这些纳米颗粒呈弥散分布,其沉淀强化增量分别为179.3MPa和257.7MPa。并对钼铌复合析出的机制进行了讨论。

The distribution,morphology,composition,crystal structure and particle size of microalloyed carbonitride precipitates in hot rolled Nb-Mo steels were examined by XRD,TEM and EDS.The results reveal that the fine and uniformly distributed MC type carbonitrides containing Mo and Nb with NaCl type structure precipitate in the steels,in which the atomic ratios of Mo to Nb in 0.081Nb-0.14Mo steel and 0.17Nb-0.12Mo steel are 0.41 and 0.22,respectively.Meanwhile,the mass percent of the fine particles(<10nm) in the two Nb-Mo steels is 58.4% and 66.1%,respectively,and the corresponding yield strength increments reach to 179.3MPa and 257.7MPa.The mechanism of the precipitation is discussed.