内涵喷管裂纹产生原因

Reason for Gracks of Inner Nozzle

某型机GH536合金制内涵喷管在工作22 h后,表面定位焊点和滚焊焊点热影响区产生裂纹,采用断口形貌、显微组织观察和化学成分测试等方法分析了裂纹的产生原因。结果表明:该内涵喷管上的裂纹为萌生时应力较大、扩展时应力较小的疲劳裂纹;内涵喷管未按工艺规定的位置进行氩弧焊定位,并且未去除定位焊点,在疲劳加载过程中,定位焊点和后续滚焊焊点热影响区存在应力集中,导致疲劳裂纹萌生。

Cracks appeared in the heat affected zone of the surface tack welding spot and roll welding spot of a GH536 alloyed inner nozzle of a certain aircraft after working for 22 h. The reason for cracks was analyzed by fracture morphology and microstructure observation and chemical composition test. The results show that the cracks on the inner nozzle were fatigue cracks initiated under a relatively large stress and propagated under a relatively small stress. The argon arc welding positioning did not meet the process requirements of the inner nozzle, and the tack welding spots were not removed. During the fatigue loading, there was stress concentration in the heat affected zone of the tack welding spot and the subsequent roll welding spot, leading to initiation of fatigue cracks.