【作者】 韩光炜； 牛建科； 杨玉军； 邓波；

【Author】 Han Guangwei~1 Niu Jianke~2 Yang Yujun~3 Deng Bo~1 (1.High Temperature Materials Research Institute,CISRI,Beijing 100081,China; 2.Pangang Group Sichuan Changcheng Special Steel Co.,Ltd.,Sichuan Jiangyou 621701,China; 3.Northeast Special Steel Group Co.,Ltd.,Liaoning Fushun 113001,China)

【机构】 钢铁研究总院高温材料研究所； 攀钢集团四川长城特殊钢股份有限公司； 东北特殊钢集团公司抚顺特殊钢股份公司；

【摘要】 本文研究了低膨胀高温合金 GH6783经650℃、700℃和750℃长期时效后的组织特征、力学性能和热膨胀系数的变化。结合 SEM 分析发现：经650℃,3000h 时效后合金中γ′相特征无明显的变化,合金的室温拉伸强度略有提高,650℃拉伸强度基本不变,而650℃的持久寿命显著延长。经700℃,1000h 时效后,γ′弥散相的尺寸明显长大,这使合金在室温、650℃的拉伸强度略有下降,但650℃的持久寿命仍有显著延长。经750℃,1000h 时效后,γ′相粗化严重,β相尺寸增大与含量明显增加,合金的组织特征发生了显著变化。这使合金的室温与高温拉伸强度和持久寿命均显著下降。长期时效后合金的热膨胀系数随温度的变化速率降低。另外发现,长期时效后在β-NiAl 相中析出富 Nb 的 Laves 相,但该相对合金的性能无明显的影响。合金在700℃以下具有优良的组织与性能稳定性。更多还原

【Abstract】 Investigation was made on changes in microstructure,mechanical properties and coefficient of thermal expansion (CTE)for low coefficient of thermal expansion superalloy GH6783 after long term aging respectively at 650℃,700℃ and 750℃。SEM examination revealed that aging at 650℃ for 3000 hours didn’t cause evident change in the characteristics of γ′ precipitates,but alloy strength at room temperature increased a little and that at 650℃ was not changed obviously,but stress rupture life at 650℃ was increased obviously.Aging at 700℃ for 1000 hours leads to a little reduction in strengths of the alloy at room temperature and 650℃ because of coarsening of γ′precipitates,but the stress rupture life at 650℃was also increased, and in the same level as that aged at 650℃ for 3000 hours.Aging at 750℃ for 1000 hours caused more reduction in strengths and sharp reduction in stress rapture life at 650℃ because of excessively coarsening of γ′ precipitates and increasing in the amount of β-NiAl phase.The variational rate of the coefficient of thermal expansion for GH6783 alloy with temperature was re- duced after long term aging.Nb-enriched Laves phase was found precipitating within β-NiAl phase after long term aging,but no evident influence was found on mechanical properties of the alloy.更多还原