超级13Cr马氏体不锈钢在CO_2及H_2S/CO_2环境中的腐蚀行为

Corrosion behaviors of super 13Cr martensitic stainless steel under CO_2 and H_2S/CO_2 environment

在模拟油田腐蚀环境中,通过高温、高压、CO2和H2S/CO2腐蚀实验及电化学测试,研究超级13Cr马氏体不锈钢的腐蚀行为.结果表明:在CO2腐蚀环境中,随着温度的升高,超级13Cr的均匀腐蚀速率呈稍微上升的趋势,点蚀轻微;在H2S、CO2共存条件下,超级13Cr的均匀腐蚀速率变化不大,点蚀严重,当Cl-的质量浓度为160g.L-1时,其最大点蚀深度可达28μm.超级13Cr的点蚀电位明显高于普通13Cr的点蚀电位,温度升高、Cl-的质量浓度增大和H2S气体的存在降低了超级13Cr的点蚀电位,而CO2对超级13Cr的点蚀电位影响不大;在N2、CO2环境中,超级13Cr的回复电位都在钝化区间,且回复电位较高,具有良好的再钝化能力.H2S气体的存在同样使超级13Cr的回复电位和点蚀电位显著降低.

The corrosion behaviors of super 13Cr martensitic stainless steel were studied with high temperature and high pressure CO 2 and H 2S/CO 2 test as well as electrochemical measurement at the simulated oilfield corrosion environment.The results show that with increasing temperature the uniform corrosion rate of super 13Cr martensitic stainless steel increases subsequently under CO 2 corrosion environment,and the pitting is very slight.Under H 2S/CO 2 corrosion environment,the uniform corrosion rate of super 13Cr martensitic stainless steel changes little,but the pitting becomes severe.When the Cl^-mass concentration is 160 g·L^-1,the max pitting depth comes to 28 μm.The pitting potential of super 13Cr martensitic stainless steel is bigger than that of common 13Cr,and it decreases with increasing temperature and Cl^-mass concentration as well as the presence of H 2S,while it changes slightly in CO 2 corrosion environment.The recovery potential of super 13Cr martensitic stainless steel is in the passivation zone under N 2 and CO 2 corrosion environment,and the higher recovery potential indicates that super 13Cr martensitic stainless steel possesses the superior re-passivation ability.At the same time,the presence of H 2S makes the recovery potential and pitting potential decrease remarkably.