Matamoros-Veloza Adriana, Stawski Tomasz M, Vargas Silvia, Neville Anne
Faculty of Engineering and Physical Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom.
Institute of Functional Surfaces, School of Mechanical Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom.
ACS Omega. 2023 Feb 23;8(9):8497-8504. doi: 10.1021/acsomega.2c07631. eCollection 2023 Mar 7.
Industries transporting CO gas-saturated fluids have infrastructures made of carbon steel. This is a good material with great mechanical properties but prone to corrosion and potential failure. Corrosion in sweet environments involves the formation of FeCO as a corrosion film, which is recognized to play a protective role under certain conditions. This work on the dissolution of corrosion films in sweet environments, under acidic and undersaturated conditions, demonstrates that the effects on the integrity of steel are far more significant than the damage observed on the surface of the corrosion film. Our results prove that dissolution of FeCO involved the presence of an amorphous phase, the intermediate formation of FeCl or FeCl, and the presence of a phase with short distance atom-atom correlations. The amorphous phase was identified as a mixture of retained γ-Fe and FeC. Partially broken α-Fe and FeC structures were identified to prove the damage on the material, confirming the interface zone without evident damage on the corrosion film. Dissolution affected both the α-Fe and FeCO, with the lattice [102̅] from the FeCO crystalline structure being the fastest to dissolve. The damage of steel at the molecular scale was evident at the macroscale with pit depths of up to 250 μm. The impact on the integrity of steel can be, therefore, more drastic than frequently reported in industrial operations of CO transport industries that use cleaning procedures (e.g., acid treatment, pigging) as part of their operational activities.
运输含一氧化碳饱和流体的行业所使用的基础设施由碳钢制成。碳钢是一种具有良好机械性能的优质材料，但容易发生腐蚀并存在潜在故障风险。在含硫化氢环境中的腐蚀会形成碳酸亚铁作为腐蚀膜，人们认为该腐蚀膜在某些条件下起到保护作用。这项关于在酸性和不饱和条件下含硫化氢环境中腐蚀膜溶解的研究表明，其对钢材完整性的影响远比在腐蚀膜表面观察到的损伤更为显著。我们的研究结果证明，碳酸亚铁的溶解涉及非晶相的存在、氯化亚铁或氯化铁的中间形成过程，以及具有短程原子间关联的相的存在。非晶相被确定为残余γ - 铁和碳化铁的混合物。部分破碎的α - 铁和碳化铁结构得以确认，证明了材料受到的损伤，证实了在腐蚀膜上没有明显损伤的界面区域。溶解过程同时影响了α - 铁和碳酸亚铁，碳酸亚铁晶体结构中的[102̅]晶格是溶解最快的部分。在宏观尺度上，钢材在分子层面的损伤表现为坑深可达250μm。因此，对钢材完整性的影响可能比在使用清洗程序（如酸处理、清管）作为运营活动一部分的一氧化碳运输行业的工业操作中经常报道的情况更为严重。
