The Microstructure Control Of Delta-processed GH4169 Alloy During Hot Working

The high temperature flow behavior and microstructure evolution of delta-processed ?DP? GH4169 alloy was studied by hot compression tests. In order to analyze the behavior of high temperature deformation, the true stress-strain curves and the microstructure of the delta phase aging at high temperature of GH4169 alloy specimens were obtained by hot compression experiments. The thermal evolution processes of the microstructure for delta-processed GH4169 were studied by optical microscope and scanning electron microscopy under different strains, strain rates and temperatures. The quantitive analysis of the 8 phase content were determined using the X-ray and the linear intercept method to observe the morphological evolution of the ? phase.Processing maps were established on the basis of the data achieved from the hot compression tests by using the principle of dynamic materials modeling.The High temperature deformation characteristics of different working conditions was sturied. The relationship of the hot working condition and microstructure was analysised. Hot working process parameters of delta-processed GH4169 were optimized.The true stress-strain curves of delta-processed GH4169 is obtained by hot compression tests, the true stress-strain curves consists of three different stages,wrok hardening stage,softening stage and steady stage. In this study the true stress-strain curves can be divided into the work hardening-dynamic recovery and dynamic flow softening stages by the peak stress,the constitutive models were established to describe the two stages.Calculation results showed that the predicted values and actual test numerical alignment is higher by introduction of standard statistical parameters.The results confirm the develop constitutive models can be used in the numerical simulation of hot forming and optimize the hot forming parameters of the studied delta-processed GH4169 alloy.By observing the microstructure, the content of delta phase in GH4169 alloy treated by DP process is gradually decreased and the size of alloy dynamic recrystallization grain increases gradually with the increase of deformation temperature or the decrease of strain rate. Through the relationship with the Z value fitting out the prediction formula of grain size. Statistics of the content of the ? phase with linear inetercept method and the X-Ray diffraction, determined the feasibility of linear inetercept method, and further verified the content of the ? phase change rule.According to the power dissipation map of 1.3 strain, the microstructure, and the relation curve and the difference chart of strain and dissipation, We found that there are three areas with higher power dissipation factor in the peak region and three processing conditions having numerical floating small dissipation. It is found that the dissipation factor is not as bigger as better.Dissipation factor is not the bigger the better based on the analysis of the power dissipation map of 1.3 strain, the microstructure, and the curves of the relationship between instability coefficient and strain rate under different strain. Generally,? phase content was little and the recrystallization grain size is larger in the microstructure of instability area. Also, there are three regions of dissipation factor greater than zero ?????>0?. All of these results suggest it is better when the processing conditions follow that the deformation temperature at 980? and the strain rate at 0.1 s^-1.