| 摘要: |
| 南海文昌滨海环境具有高温、高湿和高盐热带海洋环境特征，重大装备和设施的腐蚀非常严重，实海暴晒试验，得到海洋环境中的腐蚀数据和规律迫在眉睫。选取 304 和 316 不锈钢进行文昌滨海大气环境暴晒，用扫描电镜和 X 射线光电子能谱分析暴晒后不锈钢表面腐蚀形貌和腐蚀产物成分结构，计算不同暴晒时间后金属材料的腐蚀损耗，研究其腐蚀行为和腐蚀机理。结果显示文昌滨海环境不锈钢的腐蚀程度明显比西沙岛礁海洋环境严重。不锈钢样品随着暴晒时间的延长，表面腐蚀产物覆盖率增加，腐蚀程度加深，腐蚀机理是钝化膜受到点蚀破坏，失去保护作用，腐蚀产物增多，锈层增厚，文昌滨海热带海洋大气环境在风蚀的影响下对不锈钢产生严重腐蚀。在不锈钢表面，氯离子受风蚀、粘附、沉淀是导致不锈钢腐蚀的主要因素，由于文昌滨海热带海洋大气中存在更多的氯离子，不锈钢表面的钝化层被腐蚀造成的使用寿命和安全性能相对于其他海洋环境明显降低，造成重大影响。304、316 不锈钢的腐蚀产物基本是一样的，暴晒初期腐蚀产物是 FeOOH，长期暴晒后腐蚀产物转化为 Fe3O4、Fe2O3。但 316 不锈钢的点蚀深度要比 304 不锈钢浅，304 不锈钢暴晒 3 个月、6 个月、12 个月的平均点蚀坑深度分别为 8.29 μm、5.40 μm、6.76 μm。316 不锈钢暴晒 3 个月、6 个月、12 个月的平均点蚀坑深度分别为 2.77 μm、4.85 μm、4.10 μm。304 不锈钢暴晒 3 个月后腐蚀失重率为 0.001 5 g / (cm2 ·a)，暴晒 1 年后腐蚀失重率为 0.000 5 g / (cm2 ·a)，316 不锈钢暴晒 3 个月后腐蚀失重率为 0.001 1 g / (cm2 ·a)，暴晒 1 年后腐蚀失重率为 0. 000 5 g / (cm2 ·a)，316 不锈钢耐蚀性更好。暴晒后期点蚀坑深度会减小，因为点蚀的发展是暴晒初期快，暴晒后期发展缓慢。研究结果为南海滨海环境 304 和 316 不锈钢的防腐研究提供了真实暴晒数据及机理研究。 |
| 关键词: 南海滨海海洋环境 不锈钢 暴晒 点蚀 机理 |
| DOI：10.11933/j.issn.1007-9289.20231230004 |
| 分类号:TG171 |
| 基金项目: |
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| Corrosion Behavior and Mechanism of 304 and 316 Stainless Steel in Tropical Marine Environment |
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LAI Siying，GAO Li，LI Jinlong
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Key Laboratory of Advanced Marine Materials, Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences, Ningbo 315201 , China
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| Abstract: |
| Hainan is a tropical monsoon island. The Wenchang area is in the easternmost part of the island and is characterized by climatic characteristics such as high temperatures, high humidities, high precipitation, high salt spray content, and tropical cyclone landfall. In a tropical marine environment, which is harsh and has high air chlorine ion content, the performance of stainless steel is crucial. Marine engineering equipment is the basis for developing marine resources. The harsh corrosive environment of the ocean entails very high requirements for the corrosion resistance and safety factor of marine engineering equipment materials. Stainless steel has excellent corrosion resistance and mechanical properties, making it suitable for application in marine engineering and the oil extraction industry. Wenchang coastal area in the South China Sea is characterized by high temperature, high humidity, and high salt content, resulting in the corrosion of major equipment and facilities. In this study, 304 and 316 stainless steel were exposed to the atmospheric environment of the Wenchang coastal area. The surface corrosion morphology and corrosion product composition structure of the stainless steel were analyzed using scanning electron microscopy and X-ray photoelectron spectroscopy after atmospheric exposure. Additionally, the corrosion loss of metal materials was calculated after different exposure times to study the corrosion behavior and mechanism. The results showed that the corrosion degree of stainless steel in the Wenchang coastal area is significantly more severe than that in the Xisha Reef. As exposure time increased, the surface corrosion coverage on the stainless steel samples increased, and the degree of corrosion deepened. The corrosion mechanism was the pitting of the passivation film, loss of the protective effect, increase in corrosion products, and thickening of the rust layer. The Wenchang coastal area in the wind corrosion of stainless steel under severe corrosion. Chloride ions through wind erosion, adhesion, and precipitation are the main causes of the corrosion of stainless steel. Owing to the presence of significantly more chloride ions in the Wenchang Binhai tropical area, the passivation layer of the stainless-steel surface corrosion caused by the service life and safety performance relative to other marine environments is significantly reduced, resulting in a significant impact. The corrosion products of 304 and 316 stainless steel were basically the same. Initially, the corrosion product was FeOOH at atmospheric exposure, which transformed into Fe3O4 and finally Fe2O3 after long-term exposure. However, the pitting depth of 316 stainless steel was shallower than that of 304 stainless steel: the average pitting depths of 304 stainless steel exposed to sunlight for 3, 6, and 12 months were 8.29 μm, 5.40 μm, and 6.76 μm, respectively. Those for 316 stainless steel exposed to sunlight for 3, 6, and 12 months are 2.77 μm, 4.85 μm, and 4.10 μm, respectively. The corrosion loss rates of 304 stainless steel exposed to sunlight for 3 months and 1 year were 0.0015 g / (cm2 ?a), and 0.000 5 g / (cm2 ·a), respectively. Those of 316 stainless steel were 0.001 1 g / (cm2 ·a), and 0.000 5 g / (cm2 ·a), respectively. Thus, the corrosion resistance of 316 stainless steel was better. The depth of the pitting decreased in the late atmospheric exposure, because the development of pitting corrosion was initially rapid after atmospheric exposure, and the development of the late atmospheric exposure was slow. The results of this study provide actual exposure data and mechanisms for the corrosion protection of 304 and 316 stainless steel in the coastal environment of the South China Sea. |
| Key words: South China Sea coastal marine environment stainless steel exposure pitting mechanism |
