Abstract: Effects of different solution temperature and high aging temperature on microstructure and mechanical properties of GH4742 superalloy were studied by multi-stage heat treatment. The results show that the grain size and primary γ′ phase morphology can be significantly influenced by adjusting solution temperature. When the solution temperature is 1090 ℃, there are a large amount of undissolved primary γ′ phases in the matrix, which can effectively prevent the growth of grains, and the coexistence of those coarse primary γ′ phase and fine γ′ phase formed in the subsequent aging process makes the alloy achieves an excellent comprehensive mechanical properties. High temperature aging treatment has little effect on microstructure, but it can change the size of the γ′ phase and obviously affects the morphology of carbides on the grain boundary. By replacing Nb and Ti in the primary carbide MC with Mo, the carbides continuously distributed on the grain boundaries are dissolved to form granular carbides, which significantly reduces the high temperature durability of the GH4742 superalloy.

Key words: GH4742 alloy, solution temperature, grain size, high temperature property