热处理工艺对超级13Cr不锈钢在饱和CO_(2)油田地层水中腐蚀行为影响

Effect of Heat Treatment Process on Corrosion Behavior of Super 13Cr Stainless Steel in CO_(2)-Saturated Oilfield Formation Aqueous Solution

采用金相显微镜、XRD、电化学实验和慢应变速率拉伸等实验方法,研究了不同热处理工艺对超级13Cr不锈钢在饱和CO_(2)油田地层水中腐蚀行为的影响。结果表明,超级13Cr不锈钢经620℃回火处理后产生逆变奥氏体,二次回火处理会增加材料中逆变奥氏体的含量。不同热处理工艺下的超级13Cr不锈钢在饱和CO_(2)的油田地层水溶液中的极化曲线均存在明显钝化区间。与供货态相比,回火工艺使超级13Cr不锈钢耐蚀性下降,但二次回火能够提高材料的耐蚀性。超级13Cr耐蚀性与逆变奥氏体含量有关。淬火试样应力腐蚀开裂(SCC)敏感性最高。淬火试样、550和690℃回火试样的SCC机制为氢致开裂。620℃回火及二次回火试样因逆变奥氏体的存在,SCC敏感性降低,其开裂机制为混合断裂机制。

The corrosion behavior of super 13Cr stainless steel subjected to different heat treatment processes in CO_(2)-saturated oilfield formation water was assessed by means of metallographic microscope,XRD,electrochemical experiment and slow strain rate tensile method.The results showed that reversed austenite appeared in the super 13Cr SS after tempering at 620℃.A secondary tempering treatment could result in the increment of the amount of reversed austenite.There exists a passivation interval on polarization curves in CO_(2)-saturated oilfield formation solution for all the super 13Cr SSs after being subjected to different heat treatments.The tempering process could result in decrease in the corrosion resistance of super 13Cr SS,in the contrast,a secondary tempering could result in an enhancing effect.The corrosion resistance of super 13Cr SS was related to the content of reversed austenite.The oil-quenched 13Cr SS had the highest SCC sensitivity.The SCC mechanism of the quenched 13Cr SS,as well as the 13Cr SSs tempered at 550 and 690℃,respectively were all hydrogen induced cracking.The SCC sensitivity of 13Cr SSs after subjected to 620℃-tempering and 650℃+620℃double-tempering,decreased due to the presence of reversed austenite,accordingly,the cracking mechanism was mixed fracture.