基于电化学方法5Cr钢熔化焊接头CO2腐蚀行为

为了获得5Cr钢熔化焊焊接接头的动态腐蚀特性，采用基于电极电位的电化学方法进行5Cr钢焊接接头耐CO₂腐蚀行为的研究，建立了基于极化曲线下的腐蚀模型，研究了不同填充材料的焊接接头的耐腐蚀性. 研究发现，在温度为40 ℃，CO₂分压为10个大气压等加速腐蚀条件下，低铬焊丝的焊缝区域的自腐蚀电位最正，腐蚀速率最小，高铬焊丝的焊缝区域的自腐蚀电位较正，腐蚀速率较小，无铬焊丝的焊缝自腐蚀电位最负，腐蚀速率最大. 对比只反应腐蚀前后质量变化的失重法，电化学方法反映了腐蚀周期任一时刻的动态腐蚀速率，基于电化学腐蚀模型下的腐蚀速率与失重法测量结果相吻合. 验证了电化学腐蚀模型的正确性. 结果表明，低铬钢匹配适当的低铬焊丝可使得焊接接头具有较强的耐CO₂腐蚀性能.

Study on CO2 corrosion behavior of 5Cr steel fusion welded joint based on electrochemical method

In order to obtain the dynamic corrosion characteristics of 5Cr steel welded joints for fusion welding, the CO₂ corrosion resistance behavior of these joints was studied by using electrochemical method based on electrode potential. The corrosion model based upon polarization curve was established and the corrosion resistance of welded joints with different fillers was studied. It was found that under the accelerated corrosion conditions of temperature 40 °C and CO₂ partial pressure 10 atm, the corrosion potential of low-chromium welding wire was the most positive and the corrosion rate was the least. For high-chromium and non-chromium welding wire, corrosion potential was the more positive and the most negative, respectively. Then corrosion rate of non-chromium fillers was the highest. Compared with weight-loss method which only shows mass change before and after corrosion, the electrochemical method is concerned with the dynamic corrosion rate at any time of the corrosion cycle. The corrosion rate based on the electrochemical corrosion model showed good agreement with the results of the weight-loss method. The correctness of the electrochemical corrosion model is validated. The results showed that 5Cr steel welded joint with the match of suitable low chromium welding wire could have stronger CO₂ corrosion resistance.