Purpose

This study aims to investigate the initial corrosion behavior in aqueous solution of 20# seamless steel under (CO₂/aqueous solution) gas–liquid two-phase stratified flow conditions.

Design/methodology/approach

The initial corrosion behavior was studied through the weight loss methods, scanning electron microscopy with energy-dispersive x-ray spectroscopy and x-ray diffraction.

Findings

The corrosion rate of 20# steel obviously increases with the increasing gas pressure at different corrosion time when the CO₂ pressure is less than 0.11 MPa, and the increase of corrosion rate tends to be steady when the pressure exceeds 0.11 MPa. With the increase of CO₂ pressure, the corrosion products changed from flocculent to acicular, granular and scaly. A four-stage model for the growth of the corrosion product layer was proposed, namely, the diffusion reaction stage, the local film formation stage, the complete film formation stage and the densification stage of the product film.

Originality/value

A four-stage model for the growth of the corrosion product layer on the pipe wall surface under this condition was proposed, namely, the diffusion reaction stage, the local film formation stage, the complete film formation stage and the densification stage of the product film. The growing process and densification mechanism of corrosion products layer were discussed.

中文翻译：

---

气液两相分层流条件下20＃钢在水溶液初始腐蚀阶段的介观相变

目的

本研究旨在研究20＃无缝钢在（CO ₂ /水溶液）气液两相分层流动条件下在水溶液中的初始腐蚀行为。

设计/方法/方法

通过重量损失方法，具有能量色散X射线光谱学的扫描电子显微镜和X射线衍射对初始腐蚀行为进行了研究。

发现

当CO ₂压力小于0.11 MPa时，在不同腐蚀时间，随着气压的升高，20＃钢的腐蚀速率明显增加，而当压力超过0.11 MPa时，腐蚀速率的增加趋于稳定。随着CO ₂压力的增加，腐蚀产物从絮状变为针状，颗粒状和鳞状。提出了腐蚀产物层生长的四阶段模型，即产物膜的扩散反应阶段，局部成膜阶段，完全成膜阶段和致密化阶段。

创意/价值

提出了在此条件下腐蚀产物层在管壁表面上生长的四阶段模型，即扩散反应阶段，局部成膜阶段，完全成膜阶段和产物膜的致密化阶段。 。讨论了腐蚀产物层的生长过程和致密化机理。