Super304H钢在650℃模拟烟气侧腐蚀行为实验

摘要

The high temperature corrosion behavior of 18-8 Austenitic Super304H in coal ash/flue gas environment at 650 ℃ is investigated by means of XRD,SEM,EDS and EBSD and so on.The results show that,after corrosion for 70,150,320 and 700 h,the average thickness of corrosion layer are 2.5,5.2,11.5 and 27.8 μm,respectively.The corrosion layer is mainly composed of loose Fe2O3 at outer layer and dense Cr2O3 and internal vulcanization products at inner layer.After corrosion for 150 h,the protective Cr2O3 layer gradually desquamates and internal vulcanization products accumulate and then expand at the grain boundary.With the diffusion and dissolution of Fe to the outside of oxide film,a "nodular" Fe2O3 is formed and finally becomes a multilayered raised corrosion product.With the increase of corrosion time,the size of the "nodular" corrosion products gradually increases to more than 10 μm and the corrosion layer is more likely to rupture and peel off,which decreases the corrosion resistance of the alloy.%采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、X射线能谱仪(EDS)、电子背散射衍射(EBSD)等方法研究了18-8系奥氏体钢Super304H在650 ℃模拟烟气侧环境中高温腐蚀行为.结果表明:Super304H钢试片腐蚀70、150、320和700 h后,腐蚀层的平均厚度分别为2.5、5.2、11.5和27.8 μm;腐蚀层外层主要为疏松的Fe2O3,内层为相对致密的Cr2O3和内硫化产物.腐蚀150 h以后,试片表面保护性的Cr2O3膜逐渐剥落,内硫化产物在晶界处累积并膨胀,随着Fe向氧化膜扩散、溶解并继续向氧化膜外扩散,生成"瘤状"Fe2O3,最终成为多层的凸起腐蚀产物.随着腐蚀时间的延长,"瘤状"腐蚀产物粒径逐渐增大至10 μm以上,更易破裂、剥落的腐蚀层导致试片的抗腐蚀性不断下降.