对Q235钢在模拟某油田采出液中形成的表面产物膜, 采用光学显微镜、扫描电镜(SEM)观察其表面形貌, 通过X射线(XRD)和能谱分析产物膜的组成, 用失重法测定并研究表面垢的生长对腐蚀的影响。结果表明, Q235钢在50 ℃的试验溶液中形成的表面产物膜有三层结构, 外层FeCO3晶体较疏松, 内层FeCO3晶体较紧密, 中间层介于二者之间, 表面膜的主要成分为铁的碳酸盐。试验前3天腐蚀速率最大为0.1531 mm/a, 随着第一层膜的形成以后腐蚀速率开始下降, 24天时形成沉积膜腐蚀速率降到最低为0.0259 mm/a, 腐蚀至34天时, 由于形成的第三层膜比较松散, 腐蚀速率开始回升, 34天后腐蚀速率基本稳定。

The surface morphology of corrosion product films on surface of Q235 steel was observed by OM and SEM. The composition of films was analyzed by XRD and SEM. The corrosion rate of Q235 steel was measured by gravimetric method. The influence of surface scale growth on corrosion was studied by the corrosion rate. The results showed that there were three-layer structures of corrosion product films of Q235 steel in the solution at 50 ℃, the outer layer of FeCO3 crystals accumulated loosely, the inner layer of FeCO3 crystals accumulated closely and the size of crystals in the middle layer was between them. The main composition of surface film was FeCO3. The gravimetric method showed that the maximum value of corrosion rate was 0.1531 mm/a in the first three days, and then the corrosion rate began to decrease with the formation of the first-layer film. The minimum value of corrosion rate was 0.0259 mm/a because of deposition film on the 24 th day. The corrosion rate started to rise foom the 34 th day because the third-layer film was loose, and had no significantly change after 34 days.