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利用光学显微镜、场发射扫描电镜等手段,研究了GH864合金三种轧制态组织经热处理后的演变过程,分析了热处理后不同组织对室温冲击韧性及高温650℃裂纹扩展速率的影响.结果表明,GH864合金由初始轧制态组织经标准热处理后(1020℃,4h/空冷→845℃,4h/空冷→760℃,16h/空冷)获得的晶粒组织,其晶粒组织演变具有明显的一致性,而合金的晶界碳化物分布及基体γ’强化相没有明显差别,其分布状态及尺寸大小基本一致.热处理后的晶粒尺寸越大,抗裂纹扩展能力越好,合金的室温冲击韧性越低;热处理后形成的项链状组织,对合金冲击韧性及裂纹扩展速率有较好的影响.
The microstructure evolution of GH864 alloy after heat treatment was studied by means of optical microscopy and field emission scanning electron microscopy. The impact of different structures on room temperature impact toughness and crack growth rate at 650 ℃ was analyzed. , The microstructure of GH864 alloy is obviously consistent with the grain structure obtained from the initial rolled structure after standard heat treatment (1020 ℃, 4h / air cooling → 845 ℃, 4h / air cooling → 760 ℃, 16h / air cooling) However, the distribution of carbides in the grain boundaries and the strengthening phase of matrix γ ’did not show any significant difference, and their distributions and sizes were basically the same.The larger the grain size after heat treatment, the better the crack propagation resistance, the room temperature impact toughness The lower the heat treatment, the formation of necklace-like structure, the impact toughness of alloys and crack growth rate have a better effect.