Distribution and Characteristics of Oxide Films Formed on Stainless Steel Cladding on Low Alloy Steel in Simulated PWR Primary Water Environments
The properties of oxide film formed on stainless steel (SS) cladding on low alloy steel (LAS) after immersion in simulated PWR primary water environments with different dissolved oxygen contents are investigated. The HAZ in the LAS consist of overheated crystal region, complete recrystallized region and incompletely recrystallized region, while SS cladding consist of austenite zone and austenite and ferrite mixing zone. Pitting appeared on 309L SS after immersion in high temperature water due to the dissolution of inclusions existed previously on 309L SS which contain higher ferrite content. Raman spectra and TEM results show that the outer layer is mainly Fe-rich spinel oxides while the inner layer is mainly Cr-rich oxides. Ni is mainly concentrate at the oxide/substrate interface due to the low oxygen affinity. The inner oxide layer on 308L SS is thinner than that on 309L SS, implying that ferrite distributed on austenite is not favorable for the growth of oxides. Reducing the oxygen content in PWR primary water favored the formation of spinel oxides.
KeywordsStainless steel cladding Pressurized water reactor Low alloy steel Oxide film High temperature water
This work was supported by Shanghai Municipal Commission of Economy and Informatization No. T-221715003, National Natural Science Foundation of China (51571138), and the International Cooperative Project sponsored by Science and Technology Commission of Shanghai Municipality No. 13520721200.
- 3.J.C. Lippold, D.J. Kotecki, Welding Metallurgy and Weldability of Stainless Steels (Wiley, New Jersey, NJ, 2015), p. 376Google Scholar
- 6.G.V. Rao et al., Experience with Bimetallic Weld Cracking. in Proceedings of International Symposium Fontevraud III, (French Nuclear Energy Society, France, 1994) 1, pp. 146–153Google Scholar
- 7.O.D. Bouvier, B. Yrieix, Grain Boundary Defects Initiation at the Outer Surface of Dissimilar welds. in Proceedings of the Seventh International Symposium on Environmental Degradation of Materials in Nuclear Power Plants: Water Reactors meeting, (NACE International, Houston, 1995) 1, pp 93–104Google Scholar
- 11.H.S. Peavy, D.R. Matthews, G. Tchobanoglous, Environmental Engineering (McGraw–Hill Book Company, New York, NY, 1985), p. 694Google Scholar
- 19.C.T. Kwok, et al., Investigation of Galvanic Corrosion in Laser-Welded Stainless Steel Sheets. in Paper presented at Fifth International Symposium on Laser Precision Microfabrication, 2004, p. 5662Google Scholar
- 27.Q.S. Guo et al., Galvanic effect between ferrite and austenite in 2205 duplex stainless steel. Corros. Protect. 36(12), 1119–1123 (2015)Google Scholar