Effect of long-term aging on microstructure and properties of GH4738 superalloy
Effect of long-term aging at 650 ℃ and 700℃on microstructure and y'phase of GH4738 superalloy was studied using optical microscope and scanning electron microscopy,and its room temperature,high temperature,impact and rupture properties were tested after long-term aging.The results show that as the aging time increases during aging at 650℃,the room temperature and high temperature strength of the alloy changes less,and the rupture time first decreases and then increases.During aging at 700 ℃,the room temperature and high temperature strength,and rupture time gradually decrease with increasing aging time.The impact performance of the alloy changes less during long-term aging at 650 ℃ and 700 ℃,and the grain size and the γ'phase morphology change little,but as the aging time increases,the size of secondary γ'phase gradually increases and its content gradually decreases.By establishing strengthening models under different aging temperature and time conditions,it is revealed that the strength of the alloy is less affected by the primary y'phase during long-term aging,and the decrease in matrix strength and rupture time is mainly due to the coarsening and dissolution of the secondary γ'phase.
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