T91钢在氧浓度为0.01ppm静态铅铋合金中的界面腐蚀特征

开展了铅基反应堆候选结构材料T91钢在500℃、0.01ppm氧浓度、静态铅铋共晶合金(LBE)中的腐蚀行为研究,腐蚀时间依次为500、1 000、2 000h。采用SEM观察腐蚀界面组织形貌,并结合EDX分析界面产物成分及元素扩散行为。结果显示:T91钢发生了氧化腐蚀,表面生成了具有3层结构的氧化膜。最外层为疏松且有LBE渗透的Fe3O4层,中间层为致密且具有保护性的(Fe,Cr)3O4层,最内层为富含铬元素的内氧化层(IOZ)。随着腐蚀时间的增加,Fe3O4层和(Fe,Cr)3O4层的厚度先快速增加,在1 000h时分别达到6.5μm和7.4μm;随着腐蚀时间进一步增加,Fe3O4层的厚度略有减小而(Fe,Cr)3O4层的厚度略有增加,而IOZ的厚度却一直近似以线性规律缓慢增加。

Interface Corrosion Characteristics of T91 Steel in Static Lead-bismuth Eutectic with 0.01 ppm Oxygen

T he interface corrosion characteristics of T 91 steel , one of the candidate structural materials of lead‐based reactor ,were studied in static lead‐bismuth eutectic (LBE) with an oxygen concentration of 0.01 ppm at 500 ℃ for 500 ,1 000 and 2 000 h , respectively .The morphology at corrosion interface was examined by SEM .In addition , the product composition and element diffusion behavior were analyzed by EDX .The results show that the oxidation of T 91 steel occurs and a three‐layered oxidation film forms on the surface .The outermost layer is magnetite (Fe3O4 ) which has a porous structure penetrated by LBE ,the middle layer is (Fe ,Cr)3 O4 that is more compact and protective ,and the innermost layer is an internal oxidation zone (IOZ ) consisting of Cr‐rich oxides . With the increasing of corrosion time , the thicknesses of Fe3 O4 and (Fe ,Cr)3 O4 increase rapidly at first , w hich reach 6.5 μm and 7.4 μm at 1 000 h , respectively .Subsequently ,the thickness of Fe3O4 slightly decreases while the thick‐ness of (Fe ,Cr)3 O4 slightly increases ,but the thickness of IOZ always increases slowly with time and the grow th kinetics follow s a linear law approximately .