超级13Cr钢在含CO_2的CaCl_2完井液中应力腐蚀开裂行为

Stress Corrosion Cracking Behavior of Super 13Cr Stainless Steel in CO_2-containing CaCl_2 Completion Fluid

采用四点弯曲法实验研究了超级13Cr马氏体不锈钢在1.0MPaCO2、100℃和150℃下,密度为1.318kg/L的CaCl2完井液中的应力腐蚀开裂(SCC)行为;同时研究了溶液中氧含量和少量醋酸对应力腐蚀开裂敏感性的影响。结合动电位极化曲线,考察了材料在不同条件下的腐蚀电化学行为,其结果和四点弯曲法实验结果一致。在150℃不除氧条件下,材料的应力腐蚀开裂最敏感,此时开路电位(Ecorr)处于极化曲线上的第二个活化-钝化转换区域。扫描电子显微镜(SEM)结果显示,超级13Cr马氏体不锈钢以沿晶型方式开裂。

The stress corrosion cracking(SCC)behavior of super 13Cr martensitic stainless steel was investigated by using four-point-bend test in CaCl2 completion fluid with the density of 1.318 kg/L at 100℃ and 150℃ under 1.0 MPa of the partial pressure of carbon dioxide,and the effect of the dissolved oxygen and acetic acid on SCC was also studied.The corrosion electrochemistry behavior of the super 13Cr steel was investigated by polarization curves;the results were consistent with that of four-point bend test.The most sensitive condition for SCC of super 13Cr martensitic stainless steel was at 150℃ with dissolved oxygen,in this case the open-circuit potential(Ecorr)was located in the secondary active-passive transition zone of polarization curve.Scanning electron microscope(SEM)photographs indicated that the SCC is intergranular cracking.