Optimization Of Hot Deforming Process And Simulation Of Microstructure For GH4169 Alloy

Superalloy GH4169 has many excellent properties,such as high strength,good oxidation resistance and plasticity of hot-working,high anti-fatigue strength and so on.It is usually chosen as materials in many important high-temperature components,and widely used in aerospace and other fields.The excellent high-temperature performance of alloy GH4169 depends on development and precision control of its hot deforming process,therefore,to study the hot deforming behavior of alloy GH4169 deeply and systematically has high practical significance.In this paper,hot deformation behavior,deformation resistance and processing maps of alloy GH4169 were studied based on its thermal compressing experiment.Meanwhile,the dynamic recrystallization and ? phase precipitation in hot deformation of alloy GH4169 were simulated,and the influence of different process parameters on microstructure evolution was analyzed.Main results acquired are as follow:(1)Thermal compressing experiment of alloy GH4169 was made at different process parameters using thermal deforming test machine,in order to study its change of flow stress and evolution behavior of microstructure during plastic deforming.High-temperature constitutive equation of GH4169 was built according to the experimental true strain-stress data,the grain sizes and volume fractions of dynamic recrystallization were calculated statistically,and its evolution equations were obtained on the basis of Avrami models,providing reliable mathematical models for microstructure simulation of dynamic recrystallization by means of DEFORM-3D redevelopment.(2)Mathematical model of deformation resistance was built and process maps were drawn,according to the experimental flow stress data of alloy GH4169 in high-temperature compression at temperature 930?1080? and strain rate 1?50mm/s.giving theoretic guidance to optimize thermal deformation process parameters of alloy GH4169 and avoid region of plastic instability.(3)Based on the technology of DEFORM-3D redevelopment,mathematical models of volume fraction and grain size of dynamic recrystallization and average grain size for alloy GH4169 were written into subroutines,in order to simulate the microstructure evolution of dynamic recrystallization in thermal deformation of alloy GH4169.The comparison of simulated and experimental results showed that the prediction of the model had high accuracy.(4)Simulation platform was set up for ? phase precipitation behavior of alloy GH4169 in high-temperature aging,with CA method,through MATLAB.The shapes,distribution and amount of precipitated ? phase,both in simulation and experiment,were very similar,which verified the validation of CA method in simulation.(5)The 8 phase precipitation rules of alloy GH4169 were analyzed at different temperatures,when the compression strain rate is 50mm/s and the strain is 0.5.Volume fractions of 5 phase in metallurgical microstructures were measured by line transection method.The data,indicated that,amount of ? phase approximately kept a linear decrease with increasing of deformation temperatures.(6)On the basis of experimental results,the simulation platform with CA method was improved,and the ? phase precipitation behavior of alloy GH4169 during thermal compression at different temperatures was simulated.The shapes and distributions of precipitated ? phase obtained with silulation are similar to that with experiment.The maximum error between ? phase amount in simulation and that in experiment was 0.8%,the minimum error was 0.1%,and the mean error was 0.4%.These results verified that the simulation was correct,and proved that simulation algorithm designed in this paper was feasible.