Effect of Recovery Heat Treatment on Microstructure and Properties of IN783 Bolts in Service

Various testing techniques established the association between precipitates and the mechanical characteristics of IN783 alloy at high temperatures. The results show that the β phase is coarser at the grain boundary and that the Ni 5 Al 3 phase precipitates inside the β phase as service time increases, which destroys the structure of the β phase, weakening the strength of the grain boundary and reducing the ductility of the alloy at high temperatures. Meanwhile, increasing the size of the γ ′ phase coarser from 53 to about 74 nm enhances the yield strength of the alloy. Following the recovery heat treatment, the grain boundary β phase is precipitated again with a smaller size and no Ni 5 Al 3 , and the size of the γ ′ phase is refined to the unused level. The alloy material's high-temperature ductility is restored, which extends the material's service life.