Effect of Surface State on Nodular Corrosion Resistance of Zircaloy-4 Alloy

• Published in: Acta metallurgica sinica : English letters 2015-02, Vol.28 (2), p.254-260
• Main Authors: Chen, Chuan-Ming, Zhou, Bang-Xin, Gou, Shao-Qiu, Huang, Jiao, Yao, Mei-Yi
• Format: Article
• Language: English
• Subjects: Autoclaves; Casting; Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Corrosion effects; Corrosion resistance; Corrosion tests; Delay; Diffusion layers; Drinking water; Grain boundaries; Growth models; Materials Science; Metallic Materials; Metallurgy; Microstructure; Morphology; Nanotechnology; Nuclear fuels; Organometallic Chemistry; Oxide coatings; Oxygen ions; SEM观察; Spectroscopy/Spectrometry; Spots; Tribology; Zircaloys (trademark); Zirconium alloys; Zirconium base alloys; 合金球墨铸铁; 氧化物膜; 氧化膜; 耐腐蚀性能; 表面状态; 锆-4合金; 高压灭菌器
• ISSN: 1006-7191; 2194-1289
• DOI: 10.1007/s40195-014-0192-6

The effect of surface state on the nodular corrosion resistance of Zircaloy-4 alloy was investigated in super- heated steam at 500 ℃/10.3 MPa by autoclave tests. The microstructures of oxide films on the corroded specimens were observed by TEM and SEM. The results indicate that surface strained layer delays the appearance of nodular spots on the specimen surfaces and improves the nodular corrosion resistance. The columnar grains orientation of the oxide films formed on the specimens with surface strained layer was more consistent than that on the specimens without surface strained layer when a comparison was made on the same orientation of the grain surfaces. Such a kind of oxide micro- structure formed on the specimens with surface strained layer can hinder the diffusion of oxygen ions along the grain boundaries and delay the growth of oxide films, therefore retard the formation process of nodular spots. This indicates that the microstructure of the initial oxide films has an important influence on the subsequent growth of the oxide films.