316L不锈钢在氯离子环境中的腐蚀行为

Corrosion Behaviors of 316L Austenitic Stainless Steel in Solutions Containing Chloride Ions

为了研究316L不锈钢在含Cl-环境中的腐蚀行为,采用浸泡和电化学相结合的方法,研究了其在不同Cl-浓度溶液中不同浸泡时间的腐蚀行为,采用扫描电镜(SEM)观察了腐蚀形貌。结果表明:316L不锈钢在含Cl-环境中的点蚀程度与Cl-浓度密切相关,随着Cl-浓度的增加,点蚀程度先增大后减弱,当Cl-浓度为3%时,点蚀最严重,当Cl-浓度超过3%时,点蚀减缓;316L不锈钢在Na Cl溶液中钝化膜的形成是缓慢的,膜结构具有不完整性,为点蚀的孕育、萌生提供了结构条件,而点蚀一旦形成,在自催化作用下继续发展;316L不锈钢在含Cl-体系中的腐蚀行为是Cl-浓度与溶解氧含量两因素共同作用的结果,溶液中Cl-含量的增加一方面为加速腐蚀提供了物质条件,促进腐蚀;另一方面减少了介质中溶解氧的含量,抑制了腐蚀,两者的综合作用使腐蚀得以控制。

The corrosion behaviors of 316 L stainless steel immersed in solution containing different concentrations of Cl^- for different time were studied by the methods of immersion and electrochemistry,and the corrosion morphology was observed by scanning electron microscopy.Results showed that the pitting corrosion on the 316 L stainless steel was closely related to the concentration of Cl^-.With the increase of the concentration of Cl^-,the degree of pitting corrosion firstly increased and then decreased.When the concentration of Cl^- was 3%,the pitting corrosion was the worst,and then alleviated as the concentration of Cl^- was further increased.Moreover,the passive film was formed slowly on the steel and the structure of film was imperfect,which led to the emergence and growth of the pitting corrosion.Once formed,the pitting corrosion continued to develop by self-catalysis.The corrosion behaviors of 316 L stainless steel were determined by the concentration of Cl^- and the content of dissolved oxygen.On the one hand,the increase of the concentration of Cl^- in solution promoted the corrosion behaviors.On the other hand,the decrease of dissolved oxygen in solution restrained the corrosion.In summary,the corrosion behaviors were controlled by both of them.