ABSTRACT

Electrochemical noise (EN) measurements were applied to detect the stress corrosion cracking (SCC) of API P110 low alloy steel in simulating CO₂-containing downhole fluid during the slow strain rate test (SSRT). Several statistical parameters of potential and current transients were defined, and they were proven to be indicative of the metastable and stable pitting, as well as the initiation and propagation processes of microcracks. The EN results showed that the amplitude and lifespan of current transients increase with the CO₂ concentration. The increasing SCC susceptibility of P110 steel is mainly attributed to the decreasing pH at the crack tip, which not only accelerated the rupture of passive film on crack walls but also prolonged the lifespan of cracks advance. EN measurement may be a promising technique for the early diagnosis of SCC.

摘要

在慢应变速率测试（SSRT）中，在模拟含CO ₂的井下流体时，采用电化学噪声（EN）测量来检测API P110低合金钢的应力腐蚀开裂（SCC ）。定义了一些电位和电流瞬态的统计参数，它们被证明可指示亚稳态和稳定的点蚀，以及微裂纹的萌生和传播过程。EN结果表明，电流瞬变的幅度和寿命随CO _2的增加而增加专注。P110钢的SCC敏感性增加主要归因于裂纹尖端的pH值降低，这不仅加速了裂纹壁上钝化膜的破裂，而且延长了裂纹扩展的寿命。EN测量可能是早期诊断SCC的有前途的技术。