海洋环境中的钢焊接件除了易发生电化学腐蚀之外,还容易发生电偶腐蚀等局部腐蚀。本文通过失重法、开路电位、强极化曲线、金相显微观测和X射线衍射等测试方法研究了DH36海洋用钢焊接件S-189-2在海水介质中的电化学腐蚀行为、电偶腐蚀倾向及其腐蚀产物成分。结果表明,焊接件各个部位在海水中的腐蚀速率均较小,腐蚀电流密度在15～29μA.cm-2范围内,阴极反应由氧扩散过程控制。开路电位和电极电位均随时间负移,各个位置电极电位差较小且负移幅度接近,发生电偶腐蚀的倾向较小。腐蚀产物以γ-FeO(OH)为主。

The corrosion behaviors of welded DH36 steel S-189-2 in seawater were studied by gravimetric method,OCP determining,strong polarization curves and polarized potential distribution.SEM and XRD were used to analysis the microstructure of samples and corrosion products.The results showed that the corrosion rate of welding material,HAZ and mother material in seawater were all small,between 15~29μA·cm-2,and they were controlled by oxygen diffusion process.Both the OCP and polarized potential moved to the negative as dipping time and the potential distance of different zones were small and the number changing were nearly.So the galvanize corrosion of welded DH36 in seawater did not happen easily.The corrosion products was mainly γ-FeO(OH).