研究了3种不同Cr含量(质量分数)的奥氏体不锈钢在700℃下煤灰/高硫烟气环境中的腐蚀行为。结果表明，低Cr合金(19.13%)腐蚀最为严重，氧化膜由外层Fe₂O₃、内层Cr₂O₃及CrS组成，外层氧化膜剥落严重；中Cr合金(22.78%)氧化膜结构与低Cr合金类似，但腐蚀程度更轻；高Cr合金(24.00%)表面形成了稳定而致密的Cr₂O₃层，表现出比其他2种合金更好的抗高温腐蚀性。合金中的NbC会被氧化成Nb₂O₅分布在氧化膜中，Nb₂O₅的形成会破坏氧化膜的完整性，导致氧化膜更容易发生开裂。

With the rapid increase in thermal power generation units in China, the thermal power generation industry is facing pressures such as reducing costs, improving power generation efficiency and mitigating environmental problems. Thermal power generation units with a large capacity and high parameters result in high system efficiency, but they also amplify the corrosion failure problem of high-temperature components, especially the atmosphere/ash corrosion of outer tubes. Many studies regarding flue gas corrosion have shown that molten alkali metal sulfate can form on the surface of pipelines, causing severe corrosion damage, and the extent of corrosion is closely related to the sulfur content in raw coal. However, much attention has been paid to low-sulfur (standard coal combustion) environments in previous studies, with very few studies on high-sulfur environments. Austenitic stainless steels possessing a combination of excellent high temperature corrosion and fatigue resistances, are considered as promising construction materials for high temperature components in supercritical and ultra-supercritical fossil fuel power plants. Elements such as Cr and Nb have been shown to greatly affect the high temperature corrosion resistance of austenitic stainless steels; however few reports are available regarding the effect of Cr on corrosion resistance in high-sulfur flue gas environments and the effect of Nb on the corrosion resistance of Cr₂O₃-forming alloys. Therefore, in this study, the corrosion behavior of three types of austenitic stainless steels with different Cr contents was studied in a coal ash/high-sulfur flue gas environment at 700^oC. Results showed that low Cr alloys formed a two-layered structure: an external Fe₂O₃ layer and an internal layer with Cr₂O₃ and CrS. Medium Cr alloys developed a similar structure oxide scale to low Cr concentration alloys, but the corrosion extent was modest. Conversely, a stable and dense Cr₂O₃ layer was formed on the surface of the high Cr alloys, showing higher corrosion resistance than the other two alloys. The Nb in the alloys had some influence on the corrosion resistance of the alloys. The NbC in the alloys oxidized to Nb₂O₅ and distributed in the oxide scale. The formation of Nb₂O₅ destroyed the integrity of the oxide scale and led to the easy cracking of the oxide scale.