Study on Microstructure Evolution in GH4169 Alloy Blade during Finish Forging

Abstract

Constitutive equations and dynamic recrystallization (DRX) model of GH4169 alloy were investigated using compression tests with temperature 940(°C)-1060(°C) and strain rate 0.001(s-1)-0.1(s-1). A coupled numerical simulation between thermal-mechanical and microstructure evolution was realized through embedding the developed user subroutines into the FEM software DEFORM-3D system. The simulated results show that higher speed of upper die is useful to the DRX but much higher and lower speed of upper die go against improving the finer and uniform of grain size in the blade. Furthermore, the grains are finer and uniform in the blade body compared with those of blade rabbet and damper platform. The experimental results of microstructure under the same forging condition were studied and the average grain degrees in the blade are over 9. The calculated results of microstructure have a good agreement with the measured value from experimental data and the prediction error is less than 7.0%. Therefore, the DRX model and developed program is reliable to optimize and improve the parameters in the blade finish forging.