Cr含量对低合金管线钢CO_2腐蚀性能的影响

Effect of Cr Content on Resistance to CO_2-induced Corrosion of Low Alloy Pipeline Steels

采用高温高压反应釜和电化学方法研究Cr含量对管线钢抗CO_2腐蚀性能的影响,并运用扫描电镜及能谱分析腐蚀产物膜形貌及成分.结果表明,管线钢添加少量的Cr元素可使其在CO_2腐蚀环境中形成结构致密的富Cr腐蚀产物膜,显著提高其抗CO_2腐蚀性能.随Cr含量提高,管线钢平均腐蚀速率下降,抗局部腐蚀能力提高;而且随Cr含量提高,管线钢自腐蚀电位向正方向偏移,极化电阻增大,抗CO_2腐蚀性能提高,与平均腐蚀速率分析结果一致.

The effect of Cr content on resistance to CO_2-induced corrosion was investigated for low alloyed pipeline steels by using high-pressure high-temperature autoclave with electrochemical measurement,while the morphologies of corrosion product scales were observed by scanning electron microscope（SEM）.The results showed that Cr-enriched compact corrosion product scales might form on the steels with addition of a little amount of Cr in CO_2 containing environments, in other words,the resistance to CO_2-corrosion of the steels could be enhanced significantly by the addition of Cr.With the increasing of Cr content the average corrosion rate and the resistance to local corrosion of the steels were improved markedly.The corrosion potential of pipeline steels shifted to more positive values,and the polarization resistance increased with the increasing Cr content,which agreed with the analysis result of average corrosion rate.