It is said that,since around the LP fourth stage blades nz-12～+15% binodal and trinodal curves had torsional oscillations,and the lacing wires and lacing poles were not clean before welding,with welding silver brazing were more and more there,which caused the lacing wires crackles,lacing wires silver brazing breaking down and other most blades tangential A0 static frequency unqualified.
对某发电厂1号汽轮机低压第4级叶片拉筋大面积银焊脱落,脱焊、拉筋开裂及绝大多数叶片组切向A0静频率不合格的原因作了分析,指出:低压第4级叶片本身存在nz附近-12～+15%有双节线、三节线扭振的共振因素,加之由于拉筋与拉筋孔清理不干净,反复施焊,问题愈积愈深,银焊愈堆愈多,致使问题的发生,文中提出了处理方案并实施。