奥氏体不锈钢海洋大气环境下的应力腐蚀开裂机理研究

项目名称： 奥氏体不锈钢海洋大气环境下的应力腐蚀开裂机理研究

项目编号： No.40876048

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 黄彦良

作者单位： 中国科学院海洋研究所

项目金额： 43万元

中文摘要： 奥氏体不锈钢构件和紧固件在海洋大气环境条件下常发生应力腐蚀开裂(SCC)，因其难以预测，所以危害性很大。自从人们发现奥氏体不锈钢SCC的发生是由于在其表面有一层酸性氯离子液膜以来，一般都是通过将试样浸在模拟溶液中进行实验研究，较少考虑液膜形成过程中的SCC发展过程，且存在阳极溶解和氢脆机制的争议。本项目研究表明不锈钢试样表面粘附铁锈等外来物质时能够促进腐蚀性液膜的形成且不易干燥；在大气腐蚀过程中有氢渗入不锈钢内部，表面覆盖液膜时可检测到氢渗透电流；模拟液膜溶液中的不锈钢在一定电位范围内阴极极化和阳极极化断裂延伸率均增；阴极极化试样断裂后氢含量有所增加；形变可增加不锈钢的氢含量，排孔实验法检测到缺口尖端前沿氢渗透电流较高，但热脱附(TDS)实验未发现缺口尖端氢浓度增加，排孔实验法为实时方法，TDS反映的是平均浓度。本项目通过从金属表面液膜形成开始研究奥氏体不锈钢在大气腐蚀环境条件下SCC发生和发展过程中的氢渗透行为，结合SCC敏感性测试和氢对阳极溶解作用的研究加深了对这种条件下的SCC机制的认识，在理论上发展和完善了SCC理论，在实际应用上，可以发展SCC监测和控制技术减少损失。

中文关键词： 奥氏体不锈钢；大气环境；应力腐蚀开裂；氢渗透行为

英文摘要： Stress corrosion cracking (SCC) of Austenitic stainless steel components and tightening bolts occurs sometimes in some atmospheres especially in marine atmosphere. Because of its difficulty in prediction, the damage caused is severe. Since the discovery that the occurrence of Austenitic stainless steel SCC is a result of an acidic chloride solution film formation on the surface of the steel, it was common to study this kind of SCC by soaking the specimens in the simulated solution, less was concerned about the SCC development during the formation of solution film，and the debate between anodic dissolution and hydrogen embrittlement mechanism still exists. The study of this project showed that alien substances including rust of carbon steel facilitates the formation of corrosive solution film on the surface of stainless steel. The hydrogen permeation through stainless steel membrane was measured using electrochemical method, which shows that hydrogen can diffuse into the tested steel from the beginning of early corrosion processes. The slow strain rate test (SSRT) of the specimens in simulated film solution showed that the anodic and cathodic polarization around free corrosion potential can both increase the elongation. The Thermal Desorption Spectrum (TDS) measurement after the fail of the SSRT specimens showed the hydrogen concentration increase under cathodic potentials. The hydrogen concentration increase under deformation conditions was also confirmed. A higher hydrogen permeation current was recorded by holes in a line method ahead of notch, while the hydrogen accumulation at the tip of pre-notched specimens by TDS was not detected, which shows the very locally characteristics of hydrogen accumulation in front of notch. The research facilitated a deeper and overall understanding of the SCC mechanism and promoted the development of SCC theory of Austenitic stainless steel SCC in atmospheric corrosion environment. Practically, the research also facilitated the development of SCC monitoring and control techniques that might be possible to reduce the cost of damage.

英文关键词： Austenitic stainless steel;atmospheric environment;stress corrosion cracking;hydrogen permeation behaviour