Investigation On Dynamic Recrystallization Behavior Of FGH96Superalloy During Inertia Friction Welding Process

FGH96superalloy, designed by the principle of damage tolerance, is the second generation of domestic powder-metallurgy superalloy. FGH96superalloy can make its usage temperature up to750℃and is often employed for manufacturing Aero-engine’s hot-butt components such as turbine disks and compressor disks. Because of the high proportion of alloy elements, traditional fusion welding is no longer adequate for combining these components. However, inertial friction welding (IFW), as a kind of advanced solid joining technique, is quite suitable for these situations and has been widely accepted as the main method and standard processes in the relevant industry fields. During the IFW process of FGH96superalloy, dynamic recrystallization (DRX) takes place apparently in the welding joint area. The behavior of DRX has a direct influence on the quality of IFW joints. In order to explore the regularity of DRX phenomena and provide a guideline for optimizing joint quality, numerical simulation about the IFW process of FGH96superalloy is carried out in this paper.In this work, constitutive relationship and DRX kinetics equation of FGH96superalloy is built based on Gleeble thermo-mechanical simulation tests. These tests have been carried out at deformation temperatures of1000-1175℃and strain rate of0.001-1.0s-1on a Gleeble-1500thermo-mechanical simulator. Using hyperbolic-sine function form, the constitutive equation of FGH96superalloy is built and by carrying out regression analysis, the DRX activation energy for FGH96superalloy is calculated. Also, the DRX kinetics and grain size evolution regularity are modeled.On the platform of MSC.Marc. a2-D axial-symmetric thermo-mechanical coupled finite element model has been built to simulate the IFW processes of FGH96superalloy. The temperature and stress-strain field have been calculated. By developing user subroutines, the DRX model and the thermo-mechanical coupled model have been combined together and simulation of the microstructure evolution is enabled. The simulated results is experimentally validated by from the points of macroscopic deformation.the figure of DRX zone and grain size of the welding joint.By employing the already built model, influence of process parameters on DRX behavior of FGH96superalloy during the process of IFW has been investigated. The results show that, to a certain extent, the area of DRX region and its grain size is not sensitive to the welding process parameter, including initial angular velocity and axial pressure.