【摘要】 研究了在600MW超临界机组屏式过热器TP347H管运行5000h后的高温蒸气氧化层。通过分析蒸气氧化层成分、相结构以及Cr的分布,并结合高温水蒸气存在的情况下氧化膜生长速度,提出了高温蒸气氧化层的形成机理。由Cr的扩散探讨了晶粒尺寸对TP347H管抗高温蒸气氧化性能的影响。结果表明:CrO2(OH)2的挥发导致了外层Fe的氧化物的形成,FeCr2O4内层的形成能够有效减缓蒸气氧化进程,进入稳态氧化阶段后氧化层厚度将保持不变;同时,随晶粒尺寸的减小TP347H的抗蒸气氧化性能提高。更多还原

【Abstract】 The high-temperature steam oxide layer of TP347H steel superheater tube which run after 5,000 hours on 600MW supercritical boiler was investigated.The formation mechanism of high-temperature steam oxide layer is proposed by analysing the composition of steam oxide layer,the phase structure,the distribution of Cr and the growth rate of oxide layer in the presence of water vapor.The effect of grain size on high temperature steam oxidation resistance of TP347H steel is discussed based on the diffusion of Cr in oxide layer.The results indicate that Fe oxide can be formed with evaporation of CrO₂（OH）₂,the growth rate of steam layer can be decreased with the formation of inner FeCr₂O₄ layer,and the thickness of the oxides has been reached and kept at the steady oxidation stage.Furthermore,fine-grained steel is proved to have superior steam oxidation resistance.更多还原