High Temperature Deformation Behavior Of GH4169 Alloy

This thesis studied the effect of solution treatment on the microstructure of the GH4169 alloy. And the hot deformation behavior of the GH4169 alloy has been studied by means of hot compression deformation tests. Based on the results of hot deformation tests, the relationship between the flow stress and the deformation parameters was obtained, which was characterized in the form of a constitutive equation. The microstructure evolution of the GH4169 alloy during hot deformation was analyzed by electron back-scattered diffraction (EBSD) technique, optical microscope and transmission electron microscope (TEM) observations. The dependence of the volume fraction of the dynamic recrystallized grain on the deformation parameters was also analyzed. Meanwhile, the influence of the hot deformation behavior of the GH4169 alloy on the remained delta phase was studied considering both mechanics behavior and microstructure evolution behavior.The microstructure observation results of the GH4169 alloy with different solution treatment processes show that the fraction of the delta phase decreases with the increase of the solution temperature, accompanied with a shape evolution from short rod to spheroid. The delta phases dissolve entirely in the temperature range of 1000~1050?C and the grain size of the GH4169 alloy increases with the increase of the solution temperature and holding time. The existence of delta phases restrains the growth of grain size when treated at temperatures below the complete dissolution temperature of the delta phase, while the grains grow quickly when heated above that of the delta phase.It can be concluded from the hardness testing results that the hardness of the GH4169 alloy decreases with the increase of solution temperature and holding time. The relationship between the hardness and the grain size conformed well with the Hall-Petch equation.Results of the thermal simulation tests for samples solution treated at 1100?C 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 is determined to be 472kJ/mol by the regression analysis method. The...