Abstract:In order to investigate the microstructure characteristics and the precipitation law of equilibrium phases of Incoloy 825, the microstructure was observed by the scanning electron microscopy and the simulation analysis was conducted by Thermo-Calc software. The result indicates that there is not any precipitate at the grain boundary in the original rolling state Incoloy 825 and a few Ti carbides exist within the grains. After aging at 750 °C for 4 h, block M23C6 precipitates at the grain boundary; when aging at 980 °C, MC increases with the time increasing. The main equilibrium precipitated phases of Incoloy 825 include g ￠, a-Cr, MC and M23C6. Al, Cr, Ti and C increase the precipitation start temperature and the maximum precipitation amount of g ￠, a-Cr, MC and M23C6, respectively.