Numerical Simulation Of Microstructure Evolution During Superalloy Blade Forging

A blade is one of the most important components in aviation industry. Precision forging process is a complex process, which can be affected by deforming, heat transfer and microstructure evolvement. The microstructure can decide the quality and mechanical properties of the blade. Therefore, it is important to improve the synthetical property by predicting and controlling the microstructure of the blade. The existing Finite Element Simulation software can only predict the forming effect, but do not have the function to simulate microstructure evolvement. So, user subroutines DEF_USR have been developed and implemented into a commercial FE software DEFORM-3D. It has been used to simulate the microstructure evolution and grain growth during hot forging process,which provides the evidences for precise forging process and controlling the quality of the blade. The research and results are listed as follows:(1) Based on the simulation software DEFORM-3D, in order to have the function to simulate microstructure evolution, the mathematic models of microstructure evolution and grain growing during hot forging process have been embedded in user subroutines by using Absoft_Pro_Fortran language. Then using the program, a numerical simulation has been carried out during cylinder hot forging process; by compared the simulate results with experiment results,it is known that they are matched well, so it is proved that the development was reliability.(2) For the shape and the character of nine class GH4169 alloy blade, the precision forging process have been decided as bar-extrusion, preforging and finish-forging . The forging models in different process have been drawn by PRO/E.(3) During bar-extrusion process, the effect of different process parameters to microstructure evolution have been investigated. The results indicated that a appropriate parameter can not only gain uniform and fine grain size, but also improve the mechanical properties. The deforming temperature, the deforming rate, and the height reduction can affect the recrystallized grain size significantly. (4)With the simulation of GH4169 Precision forging process, the distributing rule of the shaping effect of blade and the evolution of microstructure has been obtained during extruding pole—dummying—finish forging processes. In the extruding pole process, the shaping effect is well, and the grain size in the pole was fined evidently; during dummying and finish forging process, the grain size in the rabbet was changed tiny, and the grain size in the body decreased from the middle part to the border part.(5)By compared the simulate results with experiment results during precision forging process, it is known that the distribution of microstructure in the cross section of blade matched well. It is proved that the precision forging process can effectively improve the distribution of microstructure. It can provide theoretical basis for the actual manufacture.