主要研究了激光增材制造GH4099合金在不同热处理状态下的显微组织与室温拉伸性能。研究结果表明：沉积态试样的显微组织主要由外延生长的柱状晶组成, 沉积态试样经过1120 ℃的固溶处理后发生了明显的再结晶, 柱状晶内部的枝晶形貌消失, 转变为细小的等轴晶组织, 而且在等轴晶内部存在许多孪晶界; 与固溶态试样相比, 时效处理后的组织没有明显差异, 显微组织仍然由细小的等轴晶组成, 晶粒没有长大, γ基体上有明显的γ′相弥散析出; 对比3种状态下的室温拉伸性能可以发现, 固溶态试样的强度最低, 塑性最高, 而固溶-时效态试样的室温力学性能最好, 呈现出较高的强度和塑性。这主要是因为高温固溶过程中发生了完全再结晶, 试样内部的位错密度有所降低, 而且没有γ′相的析出强化, 而在时效过程中, γ′相充分析出阻碍了位错运动。

Microstructures and room-temperature mechanical properties of GH4099 alloy fabricated by laser additive manufacturing after heat treatments are investigated. The results indicate that the microstructure of as-deposited sample is mainly composed of epitaxial growth columnar grains. After solution treatment at 1120 ℃, due to the occurrence of recrystallization, the columnar dendrites are replaced by fine equiaxed grains, and there are some twin boundaries in the grains. There is less difference in microstructures between the solution treated samples and the solution-aging treated samples, their microstructures are still composed of fine equiaxed grains, and the size of grains does not grow up. However, the γ′ phase precipitates in the γ matrix after the aging treatment. Compared with the tensile properties at room temperature of samples in three sates, it can be found that the solution samples have the lowest strength and highest plasticity, while the aging samples have the best performance with high strength and ductility at room temperature. The reason is that recrystallization fully takes place during the solution processing and the dislocation density is small, while the γ′ phase only precipitates after aging treatment, which can block dislocations movement.