针对不同合金元素含量的AH32系列试验钢,在模拟油船货油舱上顶板及梁架所处的含H2S海洋潮湿气氛环境中进行腐蚀模拟试验。利用SEM、EDS和XRD等手段,研究了合金元素含量对AH32钢腐蚀行为的影响并探讨了其腐蚀机制。结果表明,在该试验环境中,镍、铬、铜、钒、铌等合金元素含量较高的AH32钢在短时间内腐蚀速率较高,但随着试验时间的延长呈快速下降趋势,而合金含量较低的AH32钢腐蚀速率下降趋势较缓; 高合金含量的AH32钢耐蚀性优于低合金含量的AH32钢; 不同合金含量的AH32钢的主要腐蚀产物均为FeS1-x、FeS、Fe3O4、α-FeOOH、β-FeOOH和γ-FeOOH; 其腐蚀机理为薄液膜下受H2S和O2扩散控制的电化学腐蚀,并且随着腐蚀时间的延长,试样表面的HS-去极化过程逐渐占据主导。

The effects of alloy element contents on corrosion properties of the AH32 steel in the briny wet atmosphere containing H2S simulating the cargo oil tank corrosion environment were investigated by corrosion rate measurement, SEM, EDS and XRD. The results show that the corrosion rate of AH32 steel with higher alloy content was higher in the initial stage , and then decreased rapidly after 21 d due to higher contents of Ni, Cr, Cu, V and Nb. The corrosion resistance of the higher alloying AH32 steel was better than that of the lower alloying AH32 steel. The main corrosive products on the surface of the both AH32 steels with higher and lower alloy content are identified as FeS1-x, FeS, Fe3O4, α-FeOOH, β-FeOOH, and γ-FeOOH. The electrochemical corrosion controlled by the diffusion of H2S and O2 under the liquid film was the main corrosion mechanism. HS- depolarizing process became increasingly dominant with the increase of corrosion time.