Thermodynamic study of Ti2O3+TiN complex nucleus formation in 430 ferritic stainless steel
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摘要: 通過理論分析Ti2O3、TiN在430鐵素體不銹鋼中的形成規律,提出了凝固前沿形成Ti2O3+TiN復合核心所需的Ti、Al、O和N含量.根據該成分要求,在真空感應爐中進行實驗得到鑄錠,制備金相試樣在掃描電鏡(SEM)和透射電鏡(TEM)上觀察析出物的特征.通過SEM發現,析出物細小彌散分布,尺寸約為2μm.從形貌上看,它由兩層組成,氮化鈦圍繞氧化鈦析出.通過析出物的TEM衍射花樣進一步確認,析出物的中心層為Ti2O3,外層為TiN.合理控制鋼液成分,即使在較低鈦含量時也可以形成Ti2O3+TiN的復合核心.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.
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Key words:
- stainless steel /
- precipitates /
- thermodynamics /
- solidification
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