发动机低压涡轮工作叶片裂纹失效分析

Failure analysis of crack in aeroengine low-pressure turbine blade

针对某型发动机低压涡轮工作叶片出现裂纹故障进行失效分析。通过对故障叶片进行外观检查、断口分析、表面形貌检查、截面金相检查、材质分析及断口区域成分分析,并对叶冠工作面和非工作面的应力分布进行计算,确定了叶片裂纹性质和产生原因。实验结果表明:故障低压涡轮工作叶片叶冠工作面与非工作面裂纹为高周疲劳性质,导致叶片过早出现疲劳裂纹的主要原因是耐磨块尖部进入叶冠工作面和非工作面的转角应力集中区;同时叶片工作时产生的振动载荷也加速了疲劳裂纹的产生。最后提出了控制焊接过程中耐磨块与叶冠工作面和非工作面的尺寸,避免耐磨块尖部进入转角区域的改进建议。

In this paper,the crack of the low-pressure turbine blade of aeroengine was analyzed.The crack property and emergence were identified by visual inspection,fracture analysis,surface-microscopic inspection,section metallographic examination,material analysis,chemical component analysis as well as stress distribution calculation of blade′s crown working face and non-working face.Results indicated that the cracks on the crown working face and non-working face of low pressure turbine blade were caused by high-cycle fatigue.The tine of wear blocks entered into the stress concentration region of the corners of blade on the crown working face and non-working face,which was a critical factor leading to the fatigue cracks earlier than expected.The vibration loading accelerated the fatigue cracks.Finally,the improved proposal was provided that the distances between the wear blocks and the corners of blade′s crown working face and non-working face should be controlled in the welding process,avoiding the tine of wear blocks entering into the corner.