大流量供热机组汽轮机低压末级叶片裂纹故障原因分析  

Cause Analysis on Crack Failure of Low Pressure Last Stage Blades of Large Flow Heating Steam Turbine

作　　者：张永海[1] 谷伟伟 郭伟康 孙文兵 宁哲[1] 陈胜利[1] 史志刚[1] ZHANG Yong-hai;GU Wei-wei;GUO Wei-kang;SUN Wen-bing;NING Zhe;CHEN Sheng-li;SHI Zhi-gang(Xi'an Thermal Power Research Institute Co.,Ltd.,Xi'an 710054,China;Xi'an TPRI Energy Conservation Technology Co.,Ltd.,Xi'an 710054,China;Fujian Hongshan Thermal Power Co.,Ltd.,Shishi 362700,China)

机构地区：[1]西安热工研究院有限公司,西安710054 [2]西安西热节能技术有限公司,西安710054 [3]福建省鸿山热电有限责任公司,石狮362700

出　　处：《汽轮机技术》2022年第3期223-228,共6页Turbine Technology

摘　　要：针对某大流量供热600MW等级汽轮机低压末级动叶片连续出现的裂纹故障问题,通过叶片材料和裂纹断口理化检验及试验分析、叶片离心应力和振动特性数值计算,综合分析了叶片裂纹产生的原因,并给出了相关改进建议。该低压末级动叶片的裂纹性质为应力腐蚀开裂,叶片开裂的主要原因是高频淬火工艺过程控制不当或不严格,使淬火硬化区材料的强度高而塑性差,叶片表面材料的应力集中敏感性增加,抗疲劳性能变差,易产生晶界腐蚀;其次低压末级叶片处于湿蒸汽区,蒸汽含水量高,且存在一定量的腐蚀性元素,这些因素降低了叶片的疲劳强度,加速叶片进汽边背弧面水蚀,促进了疲劳微裂纹的萌生和扩展。Aiming at the continuous crack failure problem of the low-pressure final stage moving blade of a large-flow heating 600MW steam turbine,through the physical and chemical inspection and experimental analysis of the blade material,crack fracture,the numerical calculation of the blade centrifugal stress and vibration characteristics,comprehensive analysis of the failure caused by the blade crack Reasons and suggestions for improvement are given.The results show that the crack nature of the low-pressure final stage moving blade is stress corrosion cracking.The main cause of blade cracking is improper or inaccurate control of the high-frequency quenching process,which makes the material in the quenching hardened area high in strength but poor in plasticity,and the stress concentration of the blade surface material Sensitivity increases,fatigue resistance becomes worse,and grain boundary corrosion is likely to occur;secondly,the low-pressure final stage blades are in the wet steam zone,the steam water content is high,and there are a certain amount of corrosive elements.These factors reduce the fatigue strength of the blades and accelerate water erosion on the back arc surface of the steam inlet side of the blade promotes the initiation and propagation of fatigue micro-cracks.

关 键 词：汽轮机 故障 离心应力 淬火硬化 疲劳 分析 

分 类 号：TK263[动力工程及工程热物理—动力机械及工程]