长期时效对低膨胀高温合金GH2909性能的影响

将低膨胀高温合金GH2909分别在500℃、600℃和650℃时效2000 h,研究了长期时效对合金组织和性能的影响.结果表明:GH2909合金在550℃和600℃时效2000h后其组织稳定性较高,强度略有提高,塑性基本不变.而在650℃时效2000 h后合金的拉伸强度明显降低,室温塑性下降,尤其是在室温下断面收缩率明...

Effect of Long-term Aging on Properties of Low Expansion Superalloy GH2909

The microstructure and mechanical properties of a new type of low expansion superalloy GH2909 after long time exposure up to 2000 h at 550℃, 600℃ and 650℃ respectively were investigated. The results show that the alloy had a good microstructure stability and high mechanical properties, namely a slightly increase in strength and little change in plasticity, after aging at 550℃ and 600℃ for 2000 h. However, after 2000 h aging at 650℃ the mechanical properties of the alloy dropped significantly: the strength at room temperature and high temperature decreased significantly, and the plasticity decreased at room temperature, especially the reduction of area at room temperature decreased sharply, but the plasticity increased significantly at high temperature. This is mainly due to the precipitation of a large number of needle-like ε/ε″ phases that penetrate the grains and have "Widmanstatten structure"-like morphology in the microstructure of the alloy during the long-term aging process at 650℃, resulting in a significant reduction in the quantity of strengthening phase γ′ phases. At the same time, the stability of γ′ phase decreases at 650℃ and the size of γ′ phase increases significantly.