某直升机用主减速器滑油散热器装机使用一段时间后, 在进油管嘴与散热器焊接处出现渗油, 检查发现该处存在裂纹。通过断口宏、微观形貌观察以及焊缝截面金相检验, 确定了进油管嘴的开裂性质和开裂原因。结果表明: 主减速器滑油散热器进油管嘴的裂纹性质为高周疲劳裂纹, 管嘴开裂与其结构设计不合理有关; 通过减小管嘴长度和增加端盖厚度, 可以有效地避免进油管嘴的开裂失效。

An oil radiator in the main retarder of a helicopter cracked at the welded joint between the oil-in mouthpiece and the cover of the radiator during service. In order to find out the failure mode and failure cause, micro and macro observation as well as metallographic examination were carried out. The results show that crack of the oil-in mouthpiece of the oil radiator is high-cycle fatigue crack, and the cracking of the oil-in mouthpiece is mainly due to the improper design of the structure. The cracking of the oil-in mouthpiece could be avoided by reducing the length of the oil-in mouthpiece and increasing the thickness of the radiator cover.