Shear-compressed Thermal Deformation Behaviors Of High Strength Aluminum Alloys

7050and2024aluminum alloy are all high strength aluminum alloy which arewidely used in aerospace field. Many researches for their thermal deformation behaviorsuch as tensile, compression and torsion behaviors had been carried out in past decades. Inthis thesis, a new type of geometric sample model was used to realize pressure-shearedcompound deformation at large strain rate by means of Gleeble-3500thermal simulation.And the equivalent stress strain curve, thermal deformation microstructura, constitutiveequation, the hot working diagram were thoroughly investigated. Moreover, DEFORMfinite element numerical simulation are used to investigate pressure-sheared thermaldeformation behavior of two kinds of aluminum alloy.The results show that the equivalent flowing stress of two kinds of aluminum alloyunder the condition of hot shear-compressed deformation are influenced significantly bythe deformation temperature and strain rate. With the increase of strain rate and decreasedeformation temperature the stress increase. Due to the existence of shear force, the curvedoes not exhibit steady-state flowing feature. Through the thermal deformationmicrostructure observation, adiabatic shear phenomenon was found for two kinds ofaluminum alloy during compress-sheared deformation process, and this phenomenon ismore serious for2024aluminium alloy.7050aluminum alloy happened dynamicrecrystallization in the condition of450℃, and the faster the equivalent strain rate, thefully the dynamic recrystallization. But no dynamic recrystallization phenomenon wasfound in any test conditions of2024aluminum alloy.7050aluminum alloy pressure sheardeformation activation Q is239.9kJ/mol,2024aluminum alloy pressure sheardeformation activation Q is281.9kJ/mol.Based on dynamic material model (DMM) and Prasad instability criterion, the strain ratesensitivity index (m), energy consumption efficiency (η) and flowing instability region arecalculated under different deformation parameters. Based on the calculate results, the hotworking diagrams are drawn out. For7050aluminum alloy, with the strain increasing, theplastic instability region expand, and high temperature and low strain rate deformationparameter is fitted; The plastic instability regions of2024aluminum alloy is obviously larger than that of7050aluminum alloy, it mainly suitable for420~450℃, strain rateabout1~10s-1to the hot working process. Finally, combined with the DEFORM finiteelement numerical simulation results and test results, obtained evolution rule of equivalentstress strain and equivalent strain rate, and thermodynamic condition of microstructureformation.