某汽轮机组低压次末级叶片在运行过程中发生开裂, 通过化学成分分析、力学性能测试和金相检验等方法对叶片开裂原因进行了分析。结果表明:叶片开裂性质为疲劳开裂, 裂纹萌生于叶根最大受力面的应力集中处; 叶片型线过渡区的尖角和缺口是形成疲劳裂纹源的主要原因, 叶片近表面的夹杂物对裂纹萌生也有一定的影响。

Low pressure penultimate blades of a turbine set cracked during running, and the cracking reason was analyzed by means of chemical compositions analysis, mechanical properties testing, metallographic examination and so on. The results show that the cracking initiated at the stress concentration position on the maximum stress surface of blade root. Existing closed angle and notch at the blade shape conductor transition region was the main reason for the cracking, and inclusions near the surface also had a certain impact on the cracking