Analisis Kegagalan Retak dan Teknologi Perbaikan Sudu Turbin Jenis Inconel 792 pada Pesawat Terbang

Abstract

The failure analysis has been performed on fractured blade of turbine wheel assembly of an Auxiliary Power Unit (APU). The turbine wheel is made of as-cast nickel-base superalloy Inconel 792. To support the analysis, laboratory ractices including visual inspection, photography, stereomicroscopy, chemical composition testing, fractography, hardness testing, and metallogra- phy were conducted. Thermo-mechanical fatigue, overheating, hot corrosion, and creep are beyond the conclusion of the failure mode. The evidence shows that the fracture maybe initiated from fissures and macrocracks and then propagated to become an open-surface crack. It may come from hot cracking mechanism during previous weld repair. In addition to high content of Aluminum and Titanium in weld metal, the brittleness shown by the intergranular features compared to the transgranular cleavage facets indicate that the weldment ductility is low. Compared to unfailed blade, grain size of the failed blade is markedly different showing exposition to heat either from welding thermal cycle or abnormal operating environment at elevated temperature. Further repair scheme is developed based on successful PQTR from microhardness, nondestructive, and destructive testing. Thus, GTA Welding followed by Solution and Aging Treatment is chosen. Keywords: