Numerical Simulation On Isothermal Forging Process Of Ti-6Al-4V Frame For A Type Airplane

Ti-6Al-4V alloy is a medium-strength () two phase titanium alloy, whichhas excellent integrated performance and is widely used in aviation industry. For thepurpose of application research, Ti-6Al-4V alloy die forging is selected to make areinforced frame among rear fuselage assembly on a certain airplane instead oforiginal high-strength alloy steel. The frame is of complex shape，and demands highdimensional precision and stable inner quality．Some defects would be producedduring the forming process，such as unfilling，overlapping，and the disturbance offorging flow line, which would cause bad influence on forging quality．In this paper, numerical simulation on isothermal closed-die forming process forthe frame forging has been investigated, based on DEFORM-3D. During formingprocess, systematic research on the field variation is carried out, filling status andinner defects of workpiece are predicted, and the cause of forging defect is analyzed,which would provide valid reference for the later test verification.The main research findings are as follows:Firstly, based on the rigid-viscoplastic theories and DEFORM-3D，an isothermalcompression finite element model for Ti-6Al-4V alloy was established and the effectof different technical parameters on the deformation process and load-stroke curveswas obtained by the numerical simulation.Secondly, according to the requirement of parts drawing and relative technicaldocuments, Ti-6Al-4V alloy frame forging has been designed on the principle of equalstiffness by means of CATIA. Based on character of isothermal forging，forgingtemperature interval，die material, lubricating material as well as forging equipmentare determined. At the same time, die and billet used for numerical simulation aredesigned．Finally, the effects of billet optimization and forging technical parametersadjustment on the forming quality during Ti-6Al-4V alloy frame isothermal closed-dieforming process have been investigated，based on DEFORM-3D．The results showthat the filling of die cavity can be effectively improved by using the billet withunequal thickness，which is obtained by the analysis of material flow, as a result，thedimensional precision can be satisfied for these parts. Through adjusting forging technical parameters, the forging load can be effectively reduced, forging deformationcan be more uniform，which would ensure inner flow line and microstructureuniformity.