关键词: 不锈钢, 高温腐蚀, 元素迁移, 增重

Abstract: In this paper, candidate materials of supercritical and ultra-supercritical utility boiler water wall T23 and T24 were chosen as the experimental samples, and exposed to an oxidizing atmosphere, reducing atmosphere and oxidizing/reducing alternating atmosphere respectively. The corrosion temperature was 450℃. Besides, the effect of oxygen content and temperature on the corrosion in reducing atmosphere and alternating atmosphere was studied respectively. The scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS) were used to analyze the corroded samples. The results show that the corrosion kinetics of T23 and T24 can be described by the double logarithmic equation and parabolic equation respectively. To describe the corrosion of materials accurately it is not sufficient to just analyze the macro-weight gain and the macro-thickness of the corroded layer, the ESD must be applied at the same time to analyze the depth of the migration of the corrosive elements O and S in the corrosion. It is revealed that corrosion becomes more severe when there is H2S in the corrosive gas. S is more active than O, and Cr can disappoint the migration of oxygen instead of S. The combination corrosion of S and O and pure [S] has a stronger corrodibility than pure H2S. T24 suffers the most severe corrosion in the oxygen content of 0.8%. Corrosion is aggravated when the corrosion temperature is above 450℃ in the alternating atmosphere. T23 has a stronger corrosion resistance than T24 and W contributes a lot to the corrosion resistance of T23.