Numerical Simulation Of Stress,strain And Microstructure Evolution In Hot Working Process Of GH4169

As an ideal aero-engine material,the excellent high temperature performance of GH4169 alloy largely depends on the choice of hot working technology.In order to study the evolution law of the microstructure of forgings under deformation conditions,Gleeble hot compression test is generally adopted.For the alloy with the microstructure of GH4169 being extremely sensitive to temperature,The cooling behavior of the small sample used in Gleeble thermal simulation test is quite different from that of the large forgings used in production.Therefore,this project used DEFORM numerical simulation software to simulate the hot compression process of GH4169 alloy round bar in the temperature range of980℃ ～ 1060℃ and the deformation of 38.5% ～ 61.5%,and obtained the temperature field,strain field and three-way stress state in the hot compression process.It is found that the strain distribution at each position is very uneven during upsetting process,and the lower the initial preheating temperature is,the more serious the temperature rise of the core is,and the greater the influence of forging on the temperature of the core is.It is predicted that there are elongated grains in the region where the stress state is unidirectional tensile stress and compressive stress.Compared the v-shaped anvil and flat anvil two different molds and different rotation Angle will be 350 mm octagon billet after multichannel forging into the middle of the 270 mm octagon billet in the process of deformation temperature and strain distribution,found that selecting a v-shaped anvil of long processing time,pull the heart area low temperature to the anvil,at the same time,the core position and surface temperature difference is small,Under the condition of the same total macroscopic deformation,the total strain of the V-shaped anvil is smaller and the strain fluctuation range is smaller.The strain distribution is more uniform than that of the flat anvil,which is conducive to obtaining uniform microstructure after forging.The forging process of 22.5-90-45-90-22.5-90 rotation Angle of V-anvil is used to obtain the temperature and strain distribution in the forging process.The best effect of the three processes is obtained.The microstructure uniformity of the forgings can be improved by improving the hammer head and using V-anvil to pull out the forging process.A 65×130mm round rod was selected for the hot compression experiment.The microstructure evolution of hot compression samples was investigated by means of metallographic microscope(OM),electron backscattering diffraction(EBSD)and microhardness testing.At 980 ℃,this batch of bars could not be completely recrystallized,and the recrystallized fraction also increased with the increase of the amount of deformation.At 1020 ℃,applying 50% and 61.5% of the amount of deformation to the 1/2R and the central position of the most complete recrystallization,can obtain uniform,fine and excellent mechanical properties of the microstructure,which provides a reference for the actual production.At 1060℃,the grains of these bars are coarse and the nucleation ability of recrystallization is not as good as that of1020℃.Thin {111} twinning structures were found during the recrystallization,and the volume fraction showed the same trend as the recrystallizat ion volume fraction.When the deformation is 50% at 1020℃,the twinning is the largest.The hardness value decreases with the increase of preheating temperature.In the place where the recrystallization nucleation process is not completed,the hardness value increases with the increase of deformation.