Preform Design And Processes Simulation Of Isothermal Forging For PM Superalloy With Inclusions

Turbine disc is one of the key components of aero-engines working at high temperature. Since new powder metallurgy (PM) superalloy has much merit, such as microstructure homogeneous, high yield strength, excellent mechanical properties and fatigue capability at high temperature, etc., it has been the key material for most turbine discs of advanced aero-engines at the present time. However, PM superalloy is hard to be deformed. It has a high resistance of deformation, a narrow variation range of deformation parameters and has unstable microstructure after forging. At the same time, the inclusions, which are inevitably added in the preparation of PM superalloy, reduce the mechanical properties of the PM superalloy. Therefore, the forging technologies and quality control systems of PM turbine disc are another research emphasis besides the materials of turbine disc in the field of aeronautical engineering. Aim for the problem above, the paper has analyzed the isothermal forging processes of FGH96 superalloy turbine disc containing inclusions. The studied result is obtained.The main research findings and new outlooks are as follows:In this dissertation, the hot deformation behavior of FGH96 superalloy has been investigated by means of hot compression tests. The influences of deformation temperature, strain rate and strain on flow stress are different. On the basis of systematic analysis, a constitutive equation of FGH96 superalloy containing inclusions for the flow stress has been given. At the same time, the processing map has been obtained by the superimposition of power dissipation maps with instability maps, based on dynamic materials modeling and the stability criteria. This work provides the theory foundation for rational choice of process parameters, improving deformability of materials, control microstructure and avoiding defect.Goodier formula is introduced to calculate the stress distribution in the infinity with a sphere inclusion in it. The conclusion is that the inclusion brings stress concentration, and the most stress appears the position about equator and polaxis, and the inclusions' elasticity modulus can effectively affect the stress distribution. And lastly the results coming from the upper method are compared with the ANSYS...