先进铅冷快堆和加速器驱动次临界系统商业化的关键材料问题是结构材料与铅基冷却剂之间的相容性问题,结构钢材料需要在高温液态铅铋共晶中具有优异的抗腐蚀能力.含铝强化奥氏体钢(alumina-forming austenite steel,AFA钢)因其表面可以形成Al2O3 膜而在极端环境中具有良好的耐蚀性能.本文研究了降低Ni元素成分和高温预氧化对AFA钢耐铅铋腐蚀性能的影响,利用扫描电子显微镜、能量色散X射线光谱仪、X射线衍射技术,对AFA钢在 550℃液态铅铋饱和溶氧条件下腐蚀 600 h的氧化层形貌及结构进行表征.结果表明:降低合金中Ni含量和高温预氧化处理都会促进样品表面形成保护性Al2O3 氧化膜,进而降低腐蚀层厚度,提升材料耐铅铋腐蚀性能.
The key material issue for the commercialization of advanced lead cooled fast reactors and accelerator driven subcritical systems is the compatibility between structural materials and lead based coolants.Structural steel materials require excellent corrosion resistance in high-temperature liquid lead bismuth eutectic(LBE)alloy.Aluminum forming austenitic steel(AFA steel)has excellent corrosion resistance in extreme environments due to its ability to form an Al2O3 film on its surface.However,excessively high Ni elements are more easily dissolved or oxidized in LBE than Fe and Cr elements.Therefore,this work investigates the effect of reducing Ni element composition(25-Ni steel and 18-Ni steel)on the corrosion resistance of steel in LBE.Surface treatment can protect the substrate from corrosion to some extent,so herein we explore whether it has a protective effect on AFA steel in LBE by generating Al2O3 through high-temperature pre oxidation.The morphology and structure of the oxide layer of AFA steel corroded for 600 h in LBE with saturated dissolved oxygen at 550℃are characterized by scanning electron microscope(SEM),energy dispersive spectrometer(EDS),X-ray diffraction(XRD),and other technologies.The results indicate that the oxide film formed after corrosion of 18-Ni steel is thinner than that after corrosion of 25-Ni steel.Performing high-temperature pre oxidation is beneficial to forming a protective Al2O3 oxide film on the surface of the sample,thereby reducing the thickness of the oxide layer and improving the material's LBE corrosion resistance.The reduction in thickness of the oxide layer generated after pre oxidation of 18-Ni steel is greater than that of 25-Ni steel,so the anti-corrosion effect of 18-Ni steel after pre oxidation is better than that of 25-Ni steel.