Effects of Solution Temperature on Microstructure and Hardness of GH4710 Alloy

The effects of solution temperature on the microstructure and hardness of GH4710 alloy were studied by optical microscopy(OM) and scanning electron microscopy(SEM).The results show that the average grain size of GH4710 alloy increases gradually with the increase of solution temperature, and the degree of grain boundary flatness increases gradually, which is related to the fact that the primary γ' phase is dissolved back into the matrix at the solution temperature and the grain boundary cannot be cemented. Due to the small degree of overcooling during solution cooling, the precipitation of the secondary γ'phase does not show regularity.The morphology of the tertiary γ' phase does not change much, and it has always maintained an ellipsoid shape. The average particle size of the tertiary γ' phase first decreases and then increases. When the solution temperature is 1160 ℃, the particle size of the tertiary γ' phase is the minimum. The unit area fraction and microhardness of the tertiary γ' phase increased first and then decreased, and both reached the maximum value when the solution temperature is 1170 ℃.The change of grain size is related to the change of primary γ' phase in the alloy, and the change of hardness of GH4710 alloy is related to the distribution of the tertiary γ' phase in the alloy. The mechanism of the primary γ' phase and tertiary γ' phase in GH4710 alloy is clarified, it provides a theoretical basis for the regulation of the microstructure and properties of the alloy.