12Cr1MoV钢在高温混合碱金属氯盐中的热腐蚀行为

摘要

Hot corrosion behavior of 12Cr1MoV low alloy steel in mixed salts of 70%NaCl-30%KCl, 50%NaCl-50%KCl, 30%NaCl-70%KCl (mass fraction) at 600 ℃ and 700 ℃ was studied by the corrosion kinetic method, respectively.The corrosion morphology at the surface and cross section was observed, the composition of the corrosion products was analyzed and the corrosion mechanism was investigated.The results show that the 12Cr1MoV steel was corroded seriously at the surface and in the substrate in the high temperature mixed salts.The produced Cl2 inside the steel was the main reason for the initiation and propagation of defect structure such as cracks and pores.With the increase of KCl content in mixed salts and of the temperature, the corrosion rate of sample increased rapidly.The corrosion mode in the substrate changed from intergranular corrosion to integral corrosion due to the relatively high content of KCl.%采用腐蚀动力学分析法,研究了12Cr1MoV低合金钢在高温(600,700 ℃)70%NaCl-30%KCl、50%NaCl-50%KCl、30%NaCl-70%KCl(质量分数)混合盐中的热腐蚀行为,观察了表面及截面腐蚀形貌,分析了腐蚀产物成分并研究了其腐蚀机制.结果表明:12Cr1MoV钢在高温混合盐中会发生严重的表面与内部腐蚀,其内部产生的氯气是导致裂纹与孔洞等缺陷萌生和扩展的主要原因;随混合盐中KCl含量的增多和温度的升高,试样的腐蚀速率明显增大;较高含量的KCl使钢内部由沿晶腐蚀转变为整体性侵蚀.