一、前言 现行水轮机叶片高应力区(混流式叶片出水边靠上冠处,轴流式叶片的根部)的应力一般在1500kgf/cm~2以下,比材料的屈服极限σ_s要低得多,按照传统的强度观点是足够安全的。但是由于叶片在铸造和焊接过程中不可避免地会有一些初始缺陷,如气孔、夹渣、未焊透等,或由于气蚀和磨损在叶片表面形成一些斑点或沟槽,这些区域由于应 I. INTRODUCTION The stress in the high stress area of ​​current turbine blades (the top of the Francis blades and the root of axial blades) of the current turbine blades is generally below 1500 kgf / cm 2, which is much lower than the yield limit σ_s of the material. According to The traditional view of strength is safe enough. However, since the blade inevitably will have some initial defects during casting and welding, such as porosity, slag inclusion, incomplete penetration, etc., or some spots or grooves on the blade surface due to cavitation and wear,