供货态T91钢管内壁碳含量对海水腐蚀行为的影响

供货态T91小口径钢管内壁存在渗碳或脱碳现象，为考察内壁碳含量对其海水腐蚀行为的影响，选取内壁不同碳含量的钢管，通过浸泡失重法和电化学测试法进行实验。结果显示：内壁渗碳样品抗腐蚀性能相对较差，而内壁脱碳样品耐腐蚀性能最好；腐蚀动力学实验表明，在腐蚀初期腐蚀速率较大，而后显著降低，最后趋于稳定；海水浸泡实验表明内壁渗碳样品表面形成疏松多孔腐蚀层且易脱落，失重量约是正常样品的12倍，是轻微脱碳样品的104倍；渗碳样品内壁发生了全面腐蚀，碳含量正常样品内壁产生局部坑腐蚀，而脱碳样品内壁几乎无变化；电化学法与失重法趋势一致。

Effect of Carbon Content of Internal Wall on Corrosion Behavior of T91 Steel Tube in Simulated Seawater

In recent years, it has been found that the internal wall of the as-supplied T91 steel tube had been suffered from carburization or decarburization, which resulted in varying carbon content of the relevant internal wall surfaces. In order to investigate the effect of carbon content of the internal wall on the corrosion behavior in a simulated seawater, several samples with the same dimensions but different carbon content have been sampled from different tubes, then, of which the corrosion behavior in the simulated seawater was examined via full immersion testing and electrochemical testing. Results show that corrosion of samples taken from carburized internal walls is the worst, while the corrosion resistance of samples taken from the decarburized internal walls is the best. The immersion test revealed that the corrosion rate of samples is relatively high in the initial, then decreases significantly, and finally turns to be stable. It follows that after seawater immersion test, the samples taken from the carburized internal wall form a loose porous layer with a mass loss about 12 times of that of the sample with normal carbon content, and 104 times of that of the sample taken from the decarburized internal wall. The sample taken from with the carburized internal wall tends to experience uniform corrosion form, and the sample with normal carbon content tends to experience pitting corrosion, while the surface morphology of the sample taken from the decarburized internal wall hardly changes. The results of electrochemical test are consistent with that of weight loss test.