发动机风扇转子叶片叶身裂纹分析

发动机风扇转子叶片叶身中部区域过早产生一条裂纹。通过对故障叶片进行外观检查、断口分析、表面检查、材质分析等试验手段,确定了故障叶片裂纹性质及开裂机理。结果表明:故障风扇转子叶片裂纹为起源于叶身中部叶背侧亚表面的高周疲劳裂纹;裂纹疲劳源区附近基体组织不均匀,且存在较多的长条状初生α相,降低了叶片的疲劳性能,是导致该叶片叶身中部过早开裂的主要影响因素。改进措施为控制锻造温度并保证毛坯变形量,避免长条状初生α相的形成。

Cracking Analysis of Fan Blade in an Aero-Engine

An early crack was found in the middle of a fan blade in an aero-engine. The cracking mode and cause were analyzed by appearance observation, macro and micro observation on fracture surface, surface inspection and material analysis. The results indicate that the failure mode of the fan blade is high cycle fatigue cracking. The fatigue source was located at the sub-surface of the back side in the middle of the fan blade. The main causes for the cracking were the non-uniform distribution of metallurgical structure in the middle of the blade and lots of lath-shaped primaryαphase at the fatigue source region. The fatigue resistance of the fan blade decreased significantly. The improvement measures for avoiding formation of lath-shaped primary α phase are to control the forging temperature and to ensure the deformation degree of the raw material.