摘要
采用化学浸泡试验和电化学试验,在三氯化铁和3.5%NaCl溶液、以及模拟乏燃料池的硼酸水溶液中,研究了核电站乏燃料池覆面用S32101/ER2209双相不锈钢焊接板的点蚀行为。结果表明:在各种测试环境中,焊接板不同区域耐点蚀性能的顺序为焊缝区>母材区>热影响区,焊缝金属的耐点蚀性能最优主要是由于其Cr、Mo、Ni含量较高,而热影响区的耐点蚀性能最差是因为显微组织不良;在30,40,60℃纯硼酸溶液的电化学试验中,即使在高电位下也未观测到焊接件有明显点蚀发生,名义点蚀电位高达1 000mV(SCE)以上,而添加200mg/L Cl^-后,点蚀倾向显著增加,且温度升高导致点蚀敏感性升高。符合技术规范的纯硼酸溶液是足够好的服役环境,但加入侵蚀性Cl^-后,焊接件的点蚀抗力大幅降低,因此乏燃料池在服役期间,应严格监控水质及控制水温以避免点蚀。
The pitting corrosion behavior of S32101/ER2209 duplex stainless steel welded plate for liner of spent fuel pool of nuclear power plants in ferric chloride solution,3.5% NaCl solution and boric acid aqueous solutions simulating the environments of spent fuel pool was studied by chemical immersion testing and electrochemical testing.The results show that the corrosion resistance ranking of the parts of the welded plate was weld metal> base metal> heat affected zone in experimental environments.The weld metal had the best pitting corrosion resistance mainly due to its high content of Cr,Mo and Ni.Imperfect microstructure was the reason for the heat affected zone having the worst pitting corrosion resistance.No apparent pitting was found in the parts of the weld even at high potentials in the electrochemical tests in pure boric acid solution at 30,40 and 60℃,the nominal pitting potentials were above 1 000 mV(SCE).After adding 200 mg/L Cl^- in the pure boric acid solution,the pitting tendency increased significantly.The pitting sensitivity increased with the increase of temperature.The pure boric acid environment that meets the technical specifications is good enough for service,but when the solution contains corrosive Cl^-,the pitting corrosion resistance of welded parts will be greatly reduced.Therefore,during the service period of spent fuel pool,the water quality and water temperature should be monitored and controlled strictly to avoid pitting corrosion.
作者
赵迪
李光福
纪开强
郑会
钟志民
ZHAO Di;LI Guangfu;JI Kaiqiang;ZHENG Hui;ZHONG Zhimin(Shanghai Key Lab of Engineering Materials Application and Evaluation,Shanghai Research Institute of Materials,Shanghai 200437,China;State Nuclear Power Plant Service Company,Shanghai 200233,China)
出处
《腐蚀与防护》
CAS
北大核心
2019年第12期861-870,共10页
Corrosion & Protection
基金
国家科技重大专项(2015ZX06002005)。
关键词
核电站
乏燃料池
双相不锈钢
硼酸
点蚀
nuclear power plant
spent fuel pool
duplex stainless steel
boric acid
pitting corrosion
