高压CO2腐蚀环境中13Cr不锈钢在应力作用下的钝化行为及其失效机制研究

13Cr stainless steel with good corrosion resistance and low-cost advantages in the wet carbon dioxide corrosion environment and as the main material of casing and tubing has been widely used in oil and gas fields with carbon dioxide. But there are various stress acts on the 13Cr stainless steel used as tubing or casing. It is not clear for failure mechanism and passive behavior of 13Cr martensitic stainless steel under stress in high pressure CO2 corrosive environment. Previous study found that the passive film structure of 13Cr was changed within service time. Relative research infer that the stress serve as decisive influence on the passive behavior of 13Cr stainless steel in high pressure carbon dioxide environment and its service security. In this proposal, the passive behavior of 13Cr martensitic stainless steel under stress in high pressure CO2 corrosive environment will firstly be studied by real-time electrochemical measurement, passive film structure analysis fine analysis of substrate/ film interface and failure morphology observation. The relationship between stress action and stability of passive film will be established and the failure mechanism and evolution of passive film under stress will be explicit. This research may promote a modified 13Cr and guide the service in oil and gas field contained carbon dioxide.

13Cr不锈钢在湿二氧化碳腐蚀环境中具有良好的耐蚀性能和低成本优势成为高含二氧化碳油气田中油套管的主要材料。13Cr油套管服役时需承受各类应力，且应力作用下高压二氧化碳腐蚀环境中13Cr不锈钢的钝化行为及失效机制尚不清楚。前期研究发现钝化膜随服役时间发生显著改变，相关研究推断应力作用对13Cr不锈钢在高压二氧化碳环境中的钝化行为具有决定性影响，并影响其服役安全性。本项目以13Cr不锈钢为研究材料，采用电化学实时监测、观察分析钝化膜结构、基体/膜层界面及失效形态，揭示高压二氧化碳腐蚀环境中13Cr不锈钢在应力作用下的钝化行为，构建钝化膜的稳定性与应力作用之间的对应关系，明确膜层在应力作用下的演化及失效机制，为13Cr不锈钢更好服役以及开发升级提供理论依据。

13Cr不锈钢在湿二氧化碳腐蚀环境中具有良好的耐蚀性能和低成本优势成为高含二氧化碳.油气田中油套管的主要材料。研究结果表明13Cr不锈钢在高压二氧化碳环境下，当溶液为10%NaCl中，13Cr不锈钢具有最好的耐蚀性能，其中5%NaCl的应力腐蚀敏感性最大。温度之于13Cr的影响则是随着温度升高，应力腐蚀敏感性增加，直到90℃达到最大。而二氧化碳分压则是随着分压升高，应力腐蚀敏感性不断升高。在不同类型的拉压应力下，随着应力水平提高，13Cr不锈钢抗腐蚀性能下降，且拉应力的耐腐蚀性能远不及压应力。其中耐蚀性能均和表面的钝化膜相关，试验测试表明在二氧化碳环境中，钝化膜主要是p型半导体，其中的耐蚀性能主要受空位影响