The Finite Element Method Simulation And Optimization Of Forging Process Of New-style Aeronautical Aluminum Alloy

Aluminum alloy has a wide range application in mechanism, transportation,electricity, chemical industry and daily life. Plenty of critical parts and bearingcomponent parts are made of aluminum alloys forgings in modern aircraft. Internaltexture defects, for instance, cross-flow, through reinforcement and coarse-grain alsocan be found during aluminum alloys forge, except for surface defects, dimension andgeometrical defects. Therefore, study on the internal defects of forgings is animportant job during the forge of aluminum alloys.The flow stress features of7B04aluminum alloy were studied by isothermalcompression of cylindrical specimens at400~475℃and strain rate of1~50s-1withGleeble-3500material simulation machine to establish the material type in the FEMsimulation software. The results show that7B04aluminum alloy presents steadyflowing behavior during plastic deforming. The flow stress increased with theincrease of strain rate and decreased obviously with the increase of deformationtemperature. Furthermore constitutive model of the aluminum alloy was establishedbased on amendatory Arrhenius equation.The cross-flow defect was found on the root of the reinforcement. Andcoarse-grains were found in the cross-flow area.Subsequently, the FEM simulation of the forging process was conducted on theplatform of DEFORM-3D. And the flow of metal, the strain rate, the strain and thetemperature field were obtained after the simulation. The studies show that thecross-flow of the forging owing to these causes: the reinforcement was already fullfilled at the end of the forge process, the redundant metal of the web flow to the flashgroove with a high strain rate, and the surface layer metal of the reinforcement wascarried with the flow process. The coarse-grains in the cross-flow area were inducedby the collective recrystallization, which was stirred up by the following reasons:great deal of deformation energy was generated by the fierce shear deformation, thisalso aggravate the segregation of the second phase particle. These lead to a localoverheating because of the high temperature.In addition, the results of upset experiment of the7B04aluminum alloy showthat this alloy would form coarse-grain when the temperature is higher than490℃ and effective strain higher than0.85during the forging deformation.Finally, the process optimization of the forging was carried out by the numericalsimulation. The result show that when reduce the hammering energy to100KJ(80percent of rated energy), or modify the fillet of the reinforcement on the bottom diefrom R10to R15, the metal flow would fit the requirement of the flow lines better andthe temperature also would be lower, which can avoid the cross-flow andcoarse-grain.