Abstract Scope |
Co-based superalloys are presently an irreplaceable group of construction materials in civil and military aircraft engine components. Their fundamental production process is the technology of vacuum precision casting in multilayer shell ceramic molds. The main advantage of this process is the ability to reproduce geometrically complex shapes. The main quality requirements include dimensional tolerances and the absence of casting defects on the outer surfaces of the components. They must be met because they affect the operational durability of the whole jet engine. During the investment casting of the components, local defects may form on the surface. Instead of rejecting an item from the production cycle, the repair process could be carried out. This work aims to present the microstructure analysis of the Turballoy®605 deposited by GTAW on the X40 Co-based superalloy. TP6 plates with 6 defects (geometry specified in ISO 24394 standard) were selected for the realization of welding experiments' realization. Plates have been manufactured through investment casting. The welds were investigated by nondestructive testing, light microscopy, scanning electron
microscopy, and energy-dispersive X-ray spectroscopy. Based on visual, penetration, and radiographic
tests, the lack of critical welding imperfections was confirmed. In the cross sections of the welds, correct metallurgical bonding between the filler material and the casting was confirmed. The casting was characterized by a typical dendritic structure with numerous primary precipitates, while a fine cellular-dendritic structure was revealed in the weld. In the casting microstructure, the two types of carbide dominated, MC and M7C3. In the weld microstructure, the matrix is strengthened by carbides enriched in Cr and W. |