镍基单晶合金涡轮叶片开裂原因

某发动机高压涡轮叶片为镍基单晶合金叶片,在室温下进行振动疲劳试验后发现叶片开裂,通过宏观观察、金相检验和扫描电镜分析等方法对叶片开裂的原因进行了分析。结果表明:进气边叶根和榫头伸根的开裂形式均为疲劳开裂;进气边叶根气膜孔内壁存在多处小缺口及榫头伸根亚表面存在疏松缺陷,这些缺陷部位容易形成裂纹源,促进了裂纹的萌生,裂纹扩展后最终导致开裂失效。

Cause of Cracking on Nickel-based Single Crystal Alloy Turbine Blade

High pressure turbine blade of an engine cracked is made of nickel based single crystal alloy blade,the blade after vibration fatigue test at room temperature.The causes of cracking on blade were analyzed by means of macroscopic observation,metallographic examination and scanning electron microscope analysis.The results show that the fatigue cracking of inlet blade root and blade root stretch section was found.There were many small notches in the inner wall of air film holes of inlet blade root and the loose defects on the sub surface of blade root stretch section.The defects were easy to form crack sources,which promoted the crack initiation,and finally led to cracking failure after crack propagation.