【作者】 董希青；

【导师】 黄彦良；

【作者基本信息】 中国科学院研究生院（海洋研究所） ， 海洋化学， 2012， 博士

【摘要】 国家“十二五”规划开局之年，发展蓝色经济正式上升为国家战略。海洋资源的开发和利用，离不开海上基础设施的建设。造船业、海水淡化、石油平台和港口码头等都是当前发展最快的不锈钢应用领域。由于海洋苛刻的腐蚀环境，不锈钢构筑物的腐蚀不可避免，在自身所受作用力及腐蚀的共同影响下，不锈钢材料除了发生均匀腐蚀外，还会发生严重的局部腐蚀——应力腐蚀破裂（SCC），具有极大的破坏性。因此研究不锈钢在海洋环境下应力腐蚀开裂问题十分迫切且必要。本文模拟了在应力腐蚀开裂发展过程中，不锈钢表面腐蚀液膜的变化过程并采用Devanathan-Stachurski氢渗透技术研究了321不锈钢在此过程中的氢渗透行为。结果表明，在不锈钢表面液膜变化过程中，321不锈钢存在明显的氢渗透现象，且随着腐蚀产物浓度的增大，可检测到的氢渗透电流也是增大的，而且，氢渗透的量受不锈钢表面液膜量的影响。论文采用慢应变速率拉伸实验法(SSRT)研究了321不锈钢在模拟海洋大气环境下的应力腐蚀开裂敏感性，采用扫描电镜(SEM)观察了试样断口形貌。结果表明，随着不锈钢表面腐蚀液膜浓度的增大，不锈钢材料的应力腐蚀开裂敏感性也随之增大。而且不锈钢的应力腐蚀开裂敏感性还受所施加电位和温度的影响，阴极极化在一定极化电位内能够抑制不锈钢的应力腐蚀开裂敏感性；在常用温度范围内，温度达到55℃时，不锈钢的应力腐蚀开裂敏感性尤为明显。本文还研究了应力腐蚀开裂裂纹扩展过程中裂纹尖端和裂纹侧壁的氢渗透行为，结果表明，电化学反应产生的氢首先主要在裂纹侧壁吸附并渗透进不锈钢内部，在应力作用下向裂纹尖端迁移，导致裂纹尖端金属以氢脆的方式发生断裂。据此在申请了一项裂纹尖端和裂纹侧壁氢渗透电流检测实验法的专利。在模拟海洋大气环境表面腐蚀薄液膜下，腐蚀电位比在腐蚀溶液中要低得多且腐蚀电流密度较大。这是因为不锈钢表面有薄液膜存在的条件下，大气中的氧溶解并且扩散至电化学反应界面更加容易。随着反应的进行，阴极极化曲线出现了氧的扩散控制过程。由于薄液膜中氧的供应充足，因此可能是大量生成的腐蚀产物充满了薄液膜，阻碍了氧向反应界面扩散。更多还原

【Abstract】 At the beginning of the12thFive-Year Program（2011-2015）on NationalEconomic and Social Development, Shandong Peninsula blue economic zonedevelopment plan was adopted to be the national development strategy. A lot ofinfrastructure construction along the seashore will be built for the exploitation andutilization of marine resources. More and more stainless steel products haveapplication in shipbuilding, seawater desalination, off-shore oil platform, port and pierand so on. Stainless steel will corrode inevitably as the result of severe corrosionenvironment and stress. Besides the uniform corrosion, stress corrosion cracking(SCC) is apt to occur and brings extensive damage. So it is urgent and necessary toinvestigate the SCC of stainless steel under marine environment.The changing process of corrosion liquid film on the surface of stainless steelwas simulated in this work. The hydrogen permeation behaviors were researched byusing Devanathan-Stachurski’s hydrogen permeation technique the results showedthat obvious hydrogen permeation behaviors can be observed as the development ofcorrosion liquid film. The hydrogen permeation current observed in the experimentsincreased with the rising of concentration of corrosion products.SCC sensibility of stainless steel was studied by using slow strain rate test (SSRT)and SEM. The results showed with the increasing of corrosion film concentration,SCC sensibility also increased. SCC sensibility of stainless steel was also affected byapplied potential and temperature. SCC sensibility could be repressed when cathodicpolarization potential was applied. Meanwhile SCC sensibility was obviously increased when the temperature reached to55℃.The hydrogen permeation behaviors in crack tip and crack side of stainless steelwas also studied at the process of crack propagation. The results showed thathydrogen produced by electrochemical reaction absorbed at crack side and thenmoved to crack tip under load. At last, the metal in crack tip ruptured in the style ofhydrogen embrittlement. A patent named empirical approach of detecting hydrogenpermeation current in crack tip and crack side was applied.The corrsive reactions are easy to occur in thin film than in the solution. That isbecause the oxygen in the atmosphere dissolves into the film and diffuses to thereaction interface easily. With the proceeding of the reaction, diffusion controllingprocess appears in the cathodic polarization curves. It may be the result of mass ofcorrosive production blocking the oxygen diffusing to the reaction interface.更多还原