Effects of heat treatment on microstructure and stress rupture properties of investment casting K4169 alloy components after hot isostatically pressed（HIP）treatment have been investigated.It is found that amounts ofδ-Ni

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Nb phase with needle-like morphology can be precipitated both at the grain boundaries and in the inter-dendritic region around the carbides for the HIPed specimens with post solution and aging treatment（HIP+STA）.However

absence of Laves phase and needle-likeδ-Ni

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Nb phase precipitated in the inter-dendritic region can be observed for the HIPed specimens with direct aging treatment（HIP+DA）

and the submicronγ″phase precipitated during HIP processing is also preserved in theγ matrix.It clarifies that the hot isostatic pressing with direct aging（HIP + DA）treatment process can improve effectively creep rupture properties both in duration time and elongation.It is suggested that the network submicronγ″particles similar to lens is beneficial for creating a large number of annealing twins

which are contributed to its increase in the stress-rupture properties.