低碳微合金钢抗CO2/H2S腐蚀性能研究

针对用于可膨胀套管的低碳微合金钢CO₂/H₂S腐蚀问题，采用电极化实验、失重法及SEM等方法和手段对低碳微合金钢分别在单一H₂S（pH=2.9）、CO₂/H₂S流量比为1∶1（pH=2.9）、CO₂/H₂S流量比为1∶1（pH=5.3）条件下的腐蚀行为和规律进行研究。结果表明：低碳微合金钢在单一H2S条件下，生成了铁的硫化物，使腐蚀速率高；在有CO2存在的情况下，由于CO₂吸附在钢材表面，形成致密的吸附膜，提高了自腐蚀电位，减缓了CO₂/H₂S的腐蚀速率；由于组织不均匀及MnS的偏析，造成腐蚀后试样表面不平整，腐蚀产物膜存在微裂纹，pH值越低，腐蚀后试样表面越不平整，裂纹越明显，腐蚀越严重。

STUDY ON THE ANTI-CO2/H2S CORROSION OF LOW-CARBON MICROALLOY STEEL

To address the CO₂/H₂S corrosion of low-carbon micro-alloy steel which is used in expandable tubular，based on electrochemical experiment，weight loss method and SEM，the authors of this paper research the corrosion performance and the law of the low-carbon micro-alloy steel under the conditions of H2S only(pH=2.9)，CO₂/H₂S ( 1∶1，pH=2.9) and CO₂/H₂S (1∶1，pH=5.3).The experimental result indicates that the corrosion rate of low-carbon micro alloy steel will increase at the condition of H₂S only，as the sulfide of iron is yielding.The corrosion rate reduces when CO₂ existence，because CO₂ is adsorbed in the steel surface and the compact protective film is formed.As the uneven organization and the Segregation of MnS，sample surface is roughness，corrosion product films exist microcracks，pH value lowers，the rougher specimen surface is after corrosion，the more serious corrosion is.