430铁素体不锈钢中Ti2O3+TiN复合核心形成的热力学研究
Thermodynamic study of Ti2O3+TiN complex nucleus formation in 430 ferritic stainless steel
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摘要: 通过理论分析Ti2O3、TiN在430铁素体不锈钢中的形成规律,提出了凝固前沿形成Ti2O3+TiN复合核心所需的Ti、Al、O和N含量.根据该成分要求,在真空感应炉中进行实验得到铸锭,制备金相试样在扫描电镜(SEM)和透射电镜(TEM)上观察析出物的特征.通过SEM发现,析出物细小弥散分布,尺寸约为2μm.从形貌上看,它由两层组成,氮化钛围绕氧化钛析出.通过析出物的TEM衍射花样进一步确认,析出物的中心层为Ti2O3,外层为TiN.合理控制钢液成分,即使在较低钛含量时也可以形成Ti2O3+TiN的复合核心.Abstract: The principles of Ti2O3 and TiN formation in 430 ferritic stainless steel were theoretically analyzed. The steel's compositions including Ti, Al, O and N for forming Ti2O3 + TiN complex nuclei on solidification fronts were put forward. According to composition requirements, the experiment was conducted in a vacuum induction furnace to get an ingot. Some metallographie samples were prepared for observing the feature of precipitates under scanning electron microscopy (SEM) and transmission electron microscope (TEM). It was observed by SEM that these precipitates were fine and dispersively distributed. Their sizes were about 2 μm and titanium nitride precipitates around titanium oxide. It was further confirmed by TEM diffraction patterns of precipitates that the center layer of precipitates was Ti2O3 and the outer layer of precipitates was TiN. If the steel's composition was reasonably controlled, Ti2O3 + TiN complex nuclei can form even under a low titanium content.