Abstract: After standard heat treatment of 960 ℃×1 h+720 ℃×8 h+620 ℃×8 h, GH4169 alloy was subjected to long-term aging at 650 ℃ for 100-4000 h. The microstructure evolution law mechanical properties and their relationship of the alloy during long-term aging was explored. The results show that after aging at 650 ℃ for 100-800 h, a large number of γ″ and γ′ phases precipitate in the grain, δ phase precipitates at the grain boundary, and the hardness of the alloy increases. After aging for 1600-2400 h, γ″ and γ′ phases grow up gradually, δ phase coarsens gradually and γ″ poor zone appears around the δ phase, and the alloy hardness increases slowly. After aging for 3200-4000 h, γ″ and γ′ phases coarsen obviously and a large number of γ″ phases change into δ phase, and the hardness of the alloy decreases. Meanwhile, the tensile strength and yield strength of the alloy after long-term aging are consistent with the change of hardness, and the plasticity shows a decreasing trend.

Key words: GH4169 alloy, long-term aging, precipitated phase, mechanical properties