Sun Jianbo, Sun Chong, Lin Xueqiang, Cheng Xiangkun, Liu Huifeng
School of Mechanical and Electronic Engineering, China University of Petroleum, Qingdao 266580, China.
Materials (Basel). 2016 Mar 16;9(3):200. doi: 10.3390/ma9030200.
The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO₂ environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO₂ and H₂S coexistence conditions, the corrosion behavior of low-chromium steels in CO₂-H₂S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO₂ and H₂S. The outer scales on the three steels mainly consisted of FeS crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS, Cr(OH)₃ and FeCO₃, in contrast with the amorphous FeS and FeCO₃ mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels.
新型含铬低合金钢在二氧化碳环境中表现出良好的耐腐蚀性，这主要归功于富铬腐蚀膜的形成。为了评估其是否适用于二氧化碳和硫化氢共存的条件，采用失重测量和表面表征方法研究了低铬钢在高压高温二氧化碳-硫化氢环境中的腐蚀行为。结果表明，P110钢发生了局部腐蚀，而3Cr-P110和5Cr-P110钢均表现出全面腐蚀。然而，5Cr-P110的腐蚀速率在三者中最高。钢的腐蚀过程同时受二氧化碳和硫化氢的控制。三种钢的外层氧化皮主要由FeS晶体组成，而含铬钢的内层氧化皮由非晶态FeS、Cr(OH)₃和FeCO₃组成，这与P110钢的非晶态FeS和FeCO₃混合膜形成对比。钢中含有的铬越多，腐蚀产物中含有的铬化合物就越多。在钢中添加铬可提高富铬腐蚀氧化皮的均匀性，消除局部腐蚀，但不能降低全面腐蚀速率。FeS的形成可能会干扰富铬腐蚀氧化皮，并降低3Cr-P110和5Cr-P110钢的腐蚀性能。
