600MW超临界机组低压转子叶片开裂分析

Damage Analysis of Low-Pressure Rotor Blade of 600MW Supercritical Unit

通过宏观形貌检查、化学成分分析、力学性能试验、金相组织检验、扫描电镜及能谱分析等对某600MW超临界机组汽轮机低压转子开裂的1Cr12Mo制次次末级叶片进行了试验分析。结果表明:叶片材料塑性偏低、冲击韧性较差,在高速运行中离心力形成的拉应力和蒸汽中Cl-、S2-等腐蚀介质的共同作用下,裂纹在应力集中的蚀坑部位萌生,然后从叶片出汽侧向叶片中部横向扩展,最终导致叶片发生应力腐蚀开裂。

The damaged third last stage blade made of 1Crl2Mo martensite stainless steel of low-pressure rotor in a 600MW supereritical steam turbine was analyzed by series of tests such as macro-appearance inspection, chemical composition analysis, mechanical property testing, scanning electron microscopy and energy spectrum analysis. The results show that the impact toughness and ductility of 1Crl2Mo blade is poor. Under the combined action of blade centrifugal tensile stress and corrosion medium containing Cl- and S2- , the crack was initiated at the blade corrosion pit and then extended along the transversal blade from blade steam outlet side, at last resulted the blade stress corrosion cracking.