某超超临界机组屏式过热器发生爆管,采用宏观观察、化学成分分析、硬度测试、金相检验、扫描电镜和能谱分析等方法研究了爆管原因。结果表明:爆口附近组织发生老化,晶界析出大块或长条状σ相,越靠近爆口处,σ相数量越多,晶粒度也越大,且σ相周边存在孔洞和微裂纹,最终导致爆管。

Tube burst occurred in platen superheater of an ultra-supercritical unit. The cause of tube burst was studied by means of macroscopic observation, chemical composition analysis, hardness test, metallographic examination, scanning electron microscope and energy spectrum analysis. The results show that the microstructure near the explosion port was aged, and the large or long σ phase was precipitated at the grain boundary. The closer to the explosion port, the more σ phase, the larger the grain size, and there were holes and microcracks around the σ phase, which eventually led to the tube explosion.