Change law of microstructure and hardness of GH4698 superalloy under different heat treatment systems was studied.The results show that for the GH4698 superalloy standard heat treatment system,the primary aging cooling rate has a little effect on the size,content,spacing of y'precipitated phase and hardness.In the primary aging stage,the larger the cooling rate,the smaller the γ'phase size and the higher the hardness.When the primary aging temperature is near 1000 ℃,the γ'phase with size of 80-260 nm can precipitate effectively,which is more conducive to the subsequent secondary aging.In the secondary aging stage and in the temperature range of 725-775 ℃,the y'phase finer than 80 nm can fully precipitate,but when the temperature is below 725 ℃ and above 775 ℃,the γ'phase finer than 80 nm cannot precipitate effectively.
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