Inconel 783 superalloy bolts after about 30 000 h service at 605 ℃ were studied,and the thermodynamic equilibrium process of the tested material was simulated using Thermo-calc software to study the trends of precipitated phase types and compositions with respect to temperature.The microstructure and precipitated phase characteristics of the specimens,sampled from the thread and polished rod parts of the bolts,were investigated by means of optical metallographic microscope(OM),scanning electron microscope(SEM)and transmission electron microscope(TEM),and the mechanical properties such as Brinell hardness,tensile and impact tests were tested.The results show that the grain size at the polished rod of the bolt is slightly larger than that at the thread,and the morphology,size and quantity of γ'and βprecipitates at the thread and polished rod are roughly the same.In addition,the y'phase is mainly nano-sized particles.The β phase is mainly characterized by two features,one is relatively large in size and distributed in the grain and grain boundary,and the other is relatively small in size and distributed in the grain boundary as a network.At the same time,the precipitation of γ'phase and Heusler-Ni2AlX phase is found in the β phase.The hardness value at the thread of the bolt is higher than that at the polished rod,and the yield strength at the thread is slightly higher than that at the polished rod,but the elongation and reduction of area at the polished rod tested at high temperature are slightly higher than those at the thread.
Inconel 783 superalloyhigh temperature serviced boltsmicrostructuremechanical propertiesThermo-calc
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