Comparison of microstructural stability of IN939 superalloy with two different manufacturing routes during long-time aging

Microstructural stability of IN939 superalloy with two different manufacturing routes was investigated during long-term aging at elevated temperatures by light optical microscope (OM) and scanning electron microscope (SEM) equipped with an EDS system. The results show that the coarsening behavior of gamma particles is primarily impacted by the initial heat treatment conditions, and the effect of the prior manufacturing route (casting or hot forming) is found to be insignificant, if any, on the gamma particles coarsening kinetics. In the temperature range of 790-827 degrees C, IN939 cast/wrought-HT2 alloys have more microstructural stability, while in the temperature range of 827-910 degrees C, the initial heat treatment marked as HT1 provides more stable microstructure for the cast or wrought IN939 superalloy.