| This thesis studied the dissolution and precipitation behaviors of delta phase in GH4169 alloy under different heat treatment conditions. The curves of dissolution and precipitation for delta phase were obtained by quantitative analysis methods. The hot deformation behavior of the GH4169 alloy has been studied by hot tensile tests for both solution-treated state and delta-processed state. Based on the results of hot deformation tests, the strain rate sensitivity factors were calculated, and the relationship between the flow stress and the deformation parameters was obtained, which was characterized in the form of a constitutive equation. The effect of deformation temperature and strain rate on the microstructure of the hot deformed GH4169 alloy was analyzed by electron back-scattered diffraction (EBSD) technique, transmission electron microscope (TEM) and optical microscope observations.The microstructure observations of the GH4169 alloy under different heat treatment conditions show that the fraction of the delta phase increases with the increase of the holding time, and finally reaches a stable value. Parameters of delta phase precipitation kinetics show that the temperature corresponding to the precipitation peak is at around 900 ?C. The existence of delta phase has almost no influence on the Brinell hardness of GH4169 alloy. The microstructure observations of the GH4169 alloy with different dissolution treatment processes show that the dissolution rate of the delta phase increases with the increase of the temperature, and the delta phase can be completely dissolved at the temperature of 1035 ?C.The results of the hot tensile tests for GH4169 alloy show that the dynamic recrystallization (DRX) is the main softening mechanism of the hot deformed GH4169 alloy. The activation energy (Q) of the GH4169 alloy with solution-treated state and delta-processed state are determined to be 421.36 kJ / mol and 452.52 kJ / mol, respectively, by the regression analysis method. The relationship between the flow stress and the deformation parameters for the GH4169 alloy with solution-treated state can be described as the following equation:σp=178.57sinh-1[(1.3×10-15Z)]-4.025 The flow stress equation for the GH4169 alloy with delta-processed state can be expressed as:σp=178.57sinh-1[(6.25×10-17Z)]-4.49Microstructure analysis of the hot deformed GH4169 alloy indicate that the volume fraction of the dynamic recrystallization for the GH4169 alloy increases with the increase of temperature and the decrease of strain rate.The peak strains of hot deformation for the GH4169 alloy are decreased due to the existence of delta phase, which imply the dynamic recrystallization of the GH4169 alloy is promoted by delta phase.
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