|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Energy Materials 2017: Materials for Nuclear Energy
||Comparison of Corrosion Properties of Alloy 800 and Alloy 690 by In-situ Scratching Repassivation Behavior in High-temperature Pressurized Water
||En-Hou Han, Jiazhen Wang, Jianqiu Wang
|On-Site Speaker (Planned)
The stainless steel, nickel-base alloys and iron-nickel-base alloy were used for steam generator’s material. However, there exist the debate which materials are best for the steam generator to against corrosion and stress corrosion cracking (SCC) for long term operation. The rapid scratching method was used to evaluate the corrosion and SCC. However, it is difficult to achieve rapid scratch and measure the electrochemical signals during repassivation in high temperature high pressure (HTHP) water because the rapid scratching method requires sophisticated instrumentation to record the high current density within milli- or micro-seconds and the system manufacture and control difficulties.
The scratch electrode system in HTHP water has been built. The design temperature and design pressure of this system are 350oC and 20 MPa respectively, and the maximum scratch speed is 3.3 m/s. By using this scratch electrode system, the in-situ scratching repassivation kinetics of steam generator tube materials Alloy 800 and 690 are studied in high temperature pressurized water with different dissolved hydrogen (DH) and dissolved oxygen (DO) at 300oC.
The research results demonstrate that under DO condition the cBV value increases with the rise of DO concentration; and under DH condition, the cBV value passes through a local maximum at DH = 1.0 ppm. In addition, the repassivation results in the present work confirm the applicability of the slip-dissolution model for explaining stress corrosion cracking by means of electrochemical measurement. The scratch electrode system is valid and the scratch technique in HTHP water is a new effective and reliable method to study the SCC susceptibility of nuclear materials. Compared with other methods of evaluating stress corrosion cracking susceptibility of engineering materials, studying the repassivation kinetics by rapid scratch technique is more economical and time-efficient evaluation method for nuclear materials in high temperature pressurized water.
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