Factors Involved in Stress Corrosion Cracking of Tubes from a Nuclear Power Plant Feedwater Heater
| Autor: | Manuela Fulger, Dumitra Lucan, Maria Mihalache, Lucian Velciu |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Revista de Chimie. 70:3926-3930 |
| ISSN: | 2668-8212 0034-7752 |
| DOI: | 10.37358/rc.19.11.7674 |
| Popis: | This study has been carried out to identify the operating factors involved in the failure of two tubes made of 304 stainless steel removed from a high pressure feedwater heater working in a nuclear power plant. The samples cut from tubes have been analyzed by different methods: visual examination, optical (metallographic) microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Following analyses, on the surface of tubes was highlighted the presence of many pits in which cracks have started. Inside the pits, impurities of the type S, Cl, K, Ca were detected too. The branched cracks most likely have occurred as a result of precipitation of small amounts of chlorides deposited and concentrated on the surface of the tubes over a long period of operation. The stresses that favored this type of corrosion cracking were both residual stresses and stresses occurring at the torsion and bending of the tubes, while the high water temperature from feed heater was also a favorable factor for corrosion. The final conclusion was that the tubes failed by a chloride induced stress corrosion cracking mechanism. |
| Databáze: | OpenAIRE |
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