长期时效对GH4738合金组织性能的影响

Effect of long-term aging on microstructure and properties of GH4738 superalloy

采用光学显微镜和扫描电镜研究了650和700℃长期时效对GH4738合金组织以及γ′相的影响,并测试了其长期时效后的室温、高温、冲击及持久性能。结果表明:650℃时效时,随着时效时间增加,合金的室温、高温强度变化较小,持久断裂时间先降低后增加;700℃时效时,室温、高温强度以及持久断裂时间随着时效时间增加逐渐降低;650和700℃长时时效时合金的冲击性能变化较小,晶粒尺寸、γ′相形貌变化也较小,但随着时效时间增加,二次γ′相尺寸逐渐增大、含量逐渐降低;通过建立不同时效温度和时效时间条件下的强化模型,揭示了长期时效过程中一次γ′相对合金的强度影响较小,基体强度以及持久断裂时间的降低主要源于二次γ′相的粗化、溶解。

Effect of long-term aging at 650℃and 700℃on microstructure andγ′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 theγ′phase morphology change little,but as the aging time increases,the size of secondaryγ′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 primaryγ′phase during long-term aging,and the decrease in matrix strength and rupture time is mainly due to the coarsening and dissolution of the secondaryγ′phase.