Microstructure evolution and mechanical properties of disk superalloy under multiplex heat treatment

Turbine disks of a powder metallurgy (PM) nickel-based superalloy FGH100 were subjected to multiplex heat treatment (MHT) and investigated in terms of the improvements in their mechanical properties, which are critical for the application of these alloys in aero-engines. The effects of MHT were assessed by microstructure evolution and tensile test measurements. The results show that the microstructural characteristics of the constituent γ′ phase in the alloy change after repeated heat treatment, while the average grain sizes vary slightly. An optimized microstructure and excellent overall properties were achieved for FGH100 disk forgings by employing cyclic MHT. This study reports significant implications for the maintenance of turbines.