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Fundamental Study on Wet Corrosion Fatigue of Mild Steel by Electrochemistry

低碳钢湿腐蚀疲劳的电化学基础研究

基本信息

批准号：
01550370
负责人：
KOTOGUCHI Hisao
金额：
$ 1.15万
依托单位：
Daido Institute of Technology, Faculty of Engineering
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01550370/
关键词：
Fatigue Corrosion Fatigue Corrosion Electrochemistry Marine Cable

项目摘要

In this study, fundamental experiments were conducted in order to simulate a real corrosive environment in the laboratory and to understand the long life properties through comparatively short time test. First, Noting that the phenomena of wet-corrosion may be analyzed by the theory of electrochemistry, corrosion rates of test specimens were obtained under various environments. Second, experimental weight loss of corrosion were compared with theoretical values. The results provide basic data to obtain the limit of acceleration of corrosion rate without disturbing the corrosion process. Finally, ordinary fatigue tests in air and corrosion fatigue tests were performed to compare with both results. In the corrosion fatigue tests, specimens were attached to cell for corrosion by a 3% salt solution saturated by air. Then the fractured section of them were observed with scanning electron microscope. Main conclusion is as follows ;(1) The corrosion rate of mild steel is higher in salt water than in fresh water and is strongly affected by the dissolved oxygen in both cases. (2) In sea water, the mild steel appear to show continuously decreasing ability to withstand cyclic stress as the number of cycles of applied stress increases. (3) The corrosion fatigue strength in a sea water is less than the allowable strength in air. (4) The long life fatigue tests are required to determine the S-N curve for corrosion fatigue. This kind of tests can easily be electrochemistry performed. (5) In the surfaces that suffered corrosion fatigue, the area of brittles surface has a tendency to be larger than that of the fatigue test in air and, in addition, the percentage of brittle surface are increases as the stress level decreases. (6) Dynamic analyses of cable subjected to a fluid force were carried out, due to developing a study of fatigue strength of cable in sea water.

在本研究中，为了在实验室模拟真实的腐蚀环境，通过相对较短的时间测试了解其长寿命特性，进行了基础实验。首先，考虑到湿腐蚀现象可以用电化学理论来分析，得到了不同环境下试样的腐蚀速率。其次，将腐蚀失重实验值与理论值进行了比较。研究结果为在不干扰腐蚀过程的情况下获得加速腐蚀速率的极限提供了基础数据。最后进行了普通空气疲劳试验和腐蚀疲劳试验，比较了两种疲劳试验的结果。在腐蚀疲劳试验中，试样附着在电池上，用3%的空气饱和盐溶液进行腐蚀。然后用扫描电镜观察其断裂断面。主要结论如下；(1)低碳钢在盐水中的腐蚀速率高于在淡水中的腐蚀速率，并且在盐水和淡水中都受溶解氧的强烈影响。(2)在海水中，随着施加应力次数的增加，低碳钢的抗循环应力能力不断下降。(3)海水中的腐蚀疲劳强度小于空气中的许用强度。(4)腐蚀疲劳S-N曲线的确定需要进行长寿命疲劳试验。这种测试很容易用电化学方法进行。(5)在腐蚀疲劳试验中，脆性面面积有大于空气疲劳试验的趋势，且脆性面百分比随应力水平的降低而增加。(6)由于开展了海水中索的疲劳强度研究，对受流体力作用的索进行了动力分析。