Corrosion Behavior of a Novel Alumina-forming-austenitic Stainless Steel Exposed to Supercritical Water
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摘要: 为了丰富含铝奥氏体不锈钢（AFAs）在超临界水环境下的腐蚀行为研究数据，支持超临界水冷堆（SCWR）包壳材料评估工作，本研究对自主设计的AFAs进行600℃/25 MPa的超临界水腐蚀实验，结合微观分析表征手段分析其腐蚀行为。结果表明，本研究所用AFAs在腐蚀1000 h后的增重达34 mg/dm2，约为相同条件下的310S钢的腐蚀增重的一半。AFAs表面形成了双层氧化物，外层主要为Fe2O3和富Ni尖晶石，内层主要为Cr2O3。氧化铝以离散的颗粒形式存在于内层，阻碍扩散过程的同时可以作为Cr2O3的形核位点，促进Cr2O3的形成。因此，本研究所用AFAs在该实验条件下表现出优异的耐腐蚀性能。Abstract: In order to enrich the research data on the corrosion behavior of alumina-forming-austenitic stainless steel (AFAs) in the supercritical water environment and provide support for SCWR cladding material evaluation, this study conducted the supercritical water corrosion test at 600℃/25 MPa for the independently designed AFAs, and analyzed its corrosion behavior by combining the microscopic analysis and characterization methods. The results show that the corrosion weight gain of AFAs exposed for 1000 h is 34 mg/dm2, about half of that of 310S steel under the same conditions. There is a double-layer oxide forming on surface of AFAs. The outer layer mainly consists of Fe2O3 and Ni-rich spinel, and the inner layer is mainly composed of Cr2O3. Alumina exists in the layer as discrete particles, hindering the diffusion process and promoting the formation of Cr2O3. Therefore, AFAs in this study showed excellent corrosion resistance.
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Key words:
- Alumina-forming-austenitic stainless steel /
- Supercritical water /
- Corrosion /
- 310S steel
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图 3 AFAs和310S钢在超临界水中的腐蚀增重曲线
R2—拟合优度
Figure 3. Weight Gain Curves of AFAs and 310S Steel Exposed to Supercritical Water
图 4 AFAs在超临界水环境下随腐蚀时间变化的表面形貌
Figure 4. Surface Morphology of AFAs Exposed to Supercritical Water for Different Time
图 5 AFAs腐蚀1000 h后XRD分析结果
Figure 5. XRD Results of AFAs Exposed to Supercritical Water for 1000 h
图 6 AFAs腐蚀1000 h后截面氧化膜形貌
Figure 6. Cross-section Oxide Film Morphology of AFAs Exposed to Supercritical Water for 1000 h
图 7 腐蚀1000 h后AFAs氧化层线扫结果
Figure 7. EDS Line Scanning Results of Oxide Scale on AFAs Exposed for 1000 h
图 8 腐蚀500 h后AFAs外氧化层EDS结果
Figure 8. EDS Results of Outer Oxide Scale on AFAs Exposed for 500 h
图 9 腐蚀500 h后AFAs内氧化层EDS结果
Figure 9. EDS Results of Inner Oxide Scale on AFAs Exposed for 500 h
表 1 实验材料的化学成分
Table 1. Chemical Composition of Tested Materials
材料 元素质量分数/% Al Cr Ni Mn Mo Nb Cu Si C Fe AFAs 2.21 18.45 25.64 2.02 4.5 1.04 1.28 0.55 0.06 余量 310S 0.072 24.34 22.97 0.06 0.37 — — 0.06 0.04 余量 
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表 2 图4b标注区域的EDS点扫结果
Table 2. Point Scanning Results for Marked Area in Fig. 4b
区域 原子百分数/% O Fe Cr Ni Mn A 43.86 33.70 11.66 9.34 1.44 B 45.02 33.53 10.84 9.23 1.38 C 67.52 28.73 1.43 1.67 0.65
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