904L超级奥氏体不锈钢焊接接头的耐腐蚀性能研究

廖雪波, 张度宝, 蒲晶菁, 高超

doi:10.16577/j.issn.1001-1560.2023.0301

材料保护 >

2023 , Vol. 56 >Issue 12: 167 - 172

DOI: https://doi.org/10.16577/j.issn.1001-1560.2023.0301

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904L超级奥氏体不锈钢焊接接头的耐腐蚀性能研究

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¹福建宁德核电有限公司； ²苏州热工研究院有限公司； ³国家核电厂安全及可靠性工程技术研究中心

张度宝(1989-),硕士,工程师,主要从事核电站材料分析与寿期评估工作,电话:18306218649,E-mail:zdb15105160690@163.com

收稿日期: 2023-06-25

修回日期: 2023-07-20

录用日期: 2023-08-15

网络出版日期: 2024-01-09

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Corrosion Resistance of 904L Super Austenitic Stainless Steel Welded Joints

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(1. Fujian Ning De Nuclear Power Co., Ltd., Ningde 352000, China; 2. Suzhou Nuclear Power Institute Co., Ltd., Suzhou 215000, China;3. National Nuclear Power Plant Safety and Reliability Engineering Research Center, Suzhou 215004, China)

Received date: 2023-06-25

Revised date: 2023-07-20

Accepted date: 2023-08-15

Online published: 2024-01-09

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摘要

为了研究904L超级奥氏体不锈钢焊接接头在模拟核电厂三回路水环境中的耐腐蚀性能,采用开尔文探针力显微镜(KPFM)和电子背散射衍射(EBSD)技术,结合电化学试验、浸泡腐蚀试验研究了904L焊缝和母材晶界特征分布、表面接触电势差及介质温度对其耐腐蚀行为的影响。结果表明:904L母材具有更高的Σ3特殊晶界,较焊缝具有更好的耐腐蚀性能。焊缝和熔合线表面平均电位差分别为318 mV和295 mV,且局部区域存在电位差低谷,具有更高的电化学活性。母材和焊缝临界点蚀温度(CPT)分别为50 ℃和43 ℃,CPT焊缝<CPT母材。温度的变化对焊缝的点蚀电位(Eb)具有更大的影响,随着温度升高,焊缝点蚀电位Eb急剧降低,腐蚀速率大幅度提高。

关键词： 开尔文探针力显微镜(KPFM); 电子背散射衍射(EBSD); 接触电势差; 临界点蚀温度; 点蚀电位

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廖雪波, 张度宝, 蒲晶菁, 高超 . 904L超级奥氏体不锈钢焊接接头的耐腐蚀性能研究[J]. 材料保护, 2023 , 56(12) : 167 -172 . DOI: 10.16577/j.issn.1001-1560.2023.0301

Abstract

In order to study the corrosion resistance of 904L super austenitic stainless steel welded joints in a simulated nuclear power plant tertiary loop water environment, the Kelvin probe force microscope (KPFM), electron backscatter diffraction (EBSD), electrochemical experiments and immersion corrosion experiments were used. These methods were employed to investigate the influence of the characteristic distribution of grain boundaries of welds and base materials, surface contact potential difference and medium temperature on the corrosion resistance of 904L welded joints and base metal. Results showed that the 904L base metal had higher Σ3 special grain boundaries and exhibited better corrosion resistance than the weld. The average potential differences on the surfaces of the weld and the weld fusion line were 318 mV and 295 mV, respectively, and a potential difference valley existed in the local area, which exhibited higher electrochemical activity. The critical pitting temperatures (CPT) of the base metal and the weld were 50 ℃ and 43 ℃, respectively, CPT Weld <CPT Base Metal. The change in temperature had a greater impact on the pitting potential (Eb) of the weld. With the increase in temperature, the pitting potential Eb of weld decreased sharply, and the corrosion rate increased significantly.

Key words： the Kelvin probe force microscope (KPFM); electron backscatter diffraction (EBSD); contact potential difference; critical pitting temperature; pitting potential

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