某电厂汽轮机叶片断裂失效分析

Failure Analysis on Fracture of Steam Turbine Blades in a Power Plant

某电厂汽轮机在检修过程中发现多处叶片断裂,采用宏观分析、金相检验、断口微观分析和能谱分析等方法对汽轮机叶片的断裂原因进行了分析。结果表明:蒸汽和Cl-,S2-,Na+等与汽轮机叶片发生反应,在叶片上产生局部点腐蚀,形成腐蚀疲劳源;同时因叶片上存在离心力和蒸汽压力等复杂的周期性交变应力,最终造成汽轮机叶片发生腐蚀疲劳断裂。

Several fractured steam turbine blades were discovered in the inspection process.The fracture causes of steam turbine blades were analyzed by macro analysis,metallographic examination,fracture micro analysis,and energy spectrum analysis and so on.The results show that steam and Cl-,S2-,Na+reacted with steam turbine blades,produced local pitting corrosion on the blades,and formed corrosion fatigue source.At the same time,there were complex periodic alternating stresses such as centrifugal force and steam pressure on the blades,which eventually led to corrosion fatigue fracture of the turbine blades.