CAJ | 학술논문

某电厂600 MW亚临界机组12Cr1MoV钢末级再热器管运行51020 h后发生爆裂。采用光学显微镜、扫描电镜等设备,从宏观检查、氧化层检测、组织分析和能谱分析方面对失效管样进行研究。结果显示,爆口呈长期过热开裂宏观特征。管样向火侧氧化层过厚,组织球化严重。爆口处向火侧管壁存在明显的蠕变孔洞和沿晶裂纹,裂纹沿着晶界发展并充满氧化物。能谱分析结果显示,末级再热器管向火侧管壁在长期服役过程中,基体出现固溶合金元素贫化,导致组织劣化。综上,12Cr1MoV钢末级再热器管失效是由长期过热引起管件向火侧组织劣化、蠕变开裂造成的。
모전엄600 MW아림계궤조12Cr1MoV강말급재열기관운행51020 h후발생폭렬。채용광학현미경、소묘전경등설비,종굉관검사、양화층검측、조직분석화능보분석방면대실효관양진행연구。결과현시,폭구정장기과열개렬굉관특정。관양향화측양화층과후,조직구화엄중。폭구처향화측관벽존재명현적연변공동화연정렬문,렬문연착정계발전병충만양화물。능보분석결과현시,말급재열기관향화측관벽재장기복역과정중,기체출현고용합금원소빈화,도치조직열화。종상,12Cr1MoV강말급재열기관실효시유장기과열인기관건향화측조직열화、연변개렬조성적。
A 600 MW subcritical boiler final-stage reheater tube made of 12Cr1MoV steel cracked after running 51 020 h. The burst reheater tube was analyzed through macroscopical examination, oxidation layer measuring, microstructure and energy spectrum analysis by using optical microscope ( OM ) and scanning electron microscopy ( SEM ) . The results show that the burst exhibited a long term overheat characteristics,a thicker oxidation film forms on the fire-facing side of the burst reheater tube, and serious spheroidization of pearlite appears in microstructure. Many creep cavities and intergranular cracks are observed in the fire-facing side of the burst wall. And the cracks, extending along the grain boundaries are full filled with oxide. The results of the energy spectrum analysis show that the alloying elements are depleted in the matrix, which causing the deterioration of tube microstructure. In conclusion, deterioration of the microstructure caused by long term overheat is the main reason lead to the failure of the 12Cr1MoV hot stage reheater tube, and the creep cracking lead to a burst.