<p>Inconel 617B superalloy (IN617B) is a prospective material for the next generation of ultra-supercritical thermal power generation units, with its high-temperature reliability being crucial to the performance of associated components. This study employs scanning electron microscopy (SEM), transmission electron microscopy (TEM), and chemical composition analysis to systematically investigate the microstructural evolution of IN617B during service at 850 °C and its impact on mechanical properties. The findings reveal the presence of three types of precipitates during the aging process: M₂₃C₆, M₆C, and γ′. For aging times less than 500&#xa0;h, the precipitation of M₂₃C₆ within the matrix significantly enhances the alloy's strength. Conversely, the formation of M₆C at the grain boundaries markedly reduces impact energy. When the aging time surpasses 500&#xa0;h, M₂₃C₆ tends to precipitate and grow at the grain boundaries. Concurrently, the stability of M₂₃C₆ within the matrix diminishes, leading to its decomposition and the subsequent formation of M₆C and γ′ at the M₂₃C₆/matrix interface. This process effectively enhances the alloy's strength and maintains its stability. However, the precipitation of γ′ significantly inhibits the growth of M₆C, creating a competitive dynamic between them for Ni. Throughout the aging process, the precipitation behavior of M₂₃C₆ within the matrix was crucial in enhancing the alloy's strength, while the impact energy was primarily influenced by the precipitation behavior of M₆C at the grain boundary. The findings offer valuable insights for the regulation of the microstructure and properties of IN617B at elevated service temperatures.</p>