奥氏体304NG不锈钢在550 ℃/25 MPa超临界水中的腐蚀行为

Corrosion behavior of austenitic 304NG stainless steel in supercritical water at 550 ℃/25 MPa

摘要: 研究了304NG不锈钢在550 ℃/25 MPa超临界水中的腐蚀特性。采用扫描电镜、X射线能谱仪和X射线衍射分析了氧化膜的腐蚀形貌、组织结构和元素成分分布。实验结果表明，在550 ℃/25 MPa的超临界水中腐蚀1 000 h后，304NG不锈钢显示出优越的耐腐蚀性能，其均匀腐蚀增重速率仅为0.012 99 mg•dm^-2•h^-1。304NG不锈钢在超临界水中形成均匀致密、但带有疖状腐蚀的双层氧化膜，厚度约为2.0 μm，内层氧化膜致密而富Cr和Ni，外层氧化膜疏松而富Fe。

Abstract: The corrosion behavior of 304NG stainless steel was investigated in supercritical water (SCW) at 550 ℃/25 MPa. SEM, EDS and XRD were used to analyze the corrosion morphology, structure and element distribution of oxide film. The experiment results show that 304NG stainless steel exhibits excellent corrosion resistance and its general corrosion rate is just 0.012 99 mg•dm^-2•h^-1 after exposure to SCW at 550 ℃/25 MPa for 1 000 h. A general and compact dual-layer oxide film structure with nodular corrosion is formed on 304NG stainless steel in SCW and its thickness is about 2.0 μm. The compact inner layer is rich in Cr and Ni, while the loose outer layer is rich in Fe.