HR3C在750℃空气和水蒸气中的高温氧化行为研究

Study on Oxidation Behaviours of HR3C in Air and Pure Steam at 750 ℃

利用扫描电子显微镜、X射线衍射仪等对奥氏体不锈钢HR3C在750℃静态空气和纯水蒸气中的高温氧化行为进行了对比研究,基于对氧化膜微观结构的细致表征,探讨了HR3C在2种气氛中的氧化机制.结果表明:在2种气氛中,HR3C表面均形成连续的(Cr,Mn)2O3膜;静态空气中HR3C合金的氧化动力学均呈现分段式抛物线规律;水蒸气的存在使得(Cr,Mn)2O3膜破裂这一过程提前并大幅加速合金的氧化,导致纯水蒸气中HR3C的氧化动力学整体偏离抛物线规律;(Cr,Mn)2O3膜的破裂是膜与基体界面空洞和膜内生长应力综合作用的结果,这使得裸露的金属基体直接与高温空气或水蒸气反应,形成Fe3O4瘤状物.

The oxidation behavior of austenitic stainless steel HR3C was studied respectively in static air and pure steam for 500 h at 750 ℃ using scanning electron microscopy and X-ray diffraction, so as to in- vestigate the oxidation mechanism of HR3C in above 2 atmospheres, based on detail characterization on the microstructure of relevant oxide scales. Results show that a continuous layer of （Cr, Mn）203 scale forms on the surface of HR3C in both the atmospheres; the oxidization kinetics of HRC presents a two-stage parabolic law in static air; the existance of water vapor promotes the cracking of （Cr, Mn）203 scale, and accelarates the oxidation of the alloy, resulting in deviated parabolic law of the HR3C growth kinetics in pure steam; the cracking of （Cr, Mn）203 layer is induced by the interaction of scale/alloy interracial voids and the growth stress in the scale, which makes bare alloy directly exposed to the high-temperature air or pure steam, thus forming FeaOr nodules.