| 2026 aluminum alloy is improved based on the 2024 and 2214 aluminum alloy,it contains low levels of Fe and Si, and minor addition of Zr to inhibit recrystallization during thermo-mechanical processing,and is widely used in aviation and aerospace structural field.The flow stress behavior of 2026 aluminum alloy during compression at elevated temperature was studied by isothermal hot compression on Gleeble-1500.The deformation temperature range from 300℃to 500℃and the strain rate range from 0.01 s-1 to 10 s-1.The relationship between flow stress and strain rate,deformation temperature and deformation degree of 2026 aluminum alloy during compression at elevated temperature had been studied,and the flow stress model had been established.Microstructure evolution of 2026 aluminum alloy during compression at elevated temperature had been analyzed by using optical microscope,transmission electron microscope,X-ray diffraction.The hot compressed samples were subsequently solution treated at 500℃and aged for 12h hours at 180℃,the microstructure and mechanical propertis of which were studied.(1).The flow stress of 2026 aluminum during compression at elevated temperature depends strongly on the strain rate and deformation temperature.The results show that the true stress-true strain curves exhibit a peak stress at critical strain,after which the flow stresses decrease monotonically until high strains,showing a dynamic flow softening,the peak stress level decreases with increasing deformation temperature and decreasing strain rate,which can be represented by the Zener-Hollomon parameter Z in the hyperbolic sine equation with the hot deformation activation energy of 256.0177kJ/mol.(2).Microstructure evolution of 2026 aluminum alloy during compression at elevated temperature has been analyzed by OM,TEM.With lnZ value decreasing,the fibrous tissue trend to grow up,dynamic recovery and dynamic recrystallization occurs,the main soften mechanisms of the alloy transforms from dynamic recovery and dynamic recrystallization to dynamic particle precipitation and growth.The main dynamic recrystallization is continuous dynamic recrystallization(CDRX),have also taken place in discontinuous dynamic recrystallization(DDRX) and geometric dynamic recrystallization(GDRX).(3).2026 aluminum alloy specimens after solution treatment and artificial aging,microstructure evolution of which has been analyzed by OM,TEM,at high lnZ value,the main microstructures are fine equiaxed recrystallization grain,at low lnZ value,the main microstructures are the elongating grains with little fine equiaxed recrystallization grain.Dislocation density in the specimens is small.Solution treatment and artificial aging process of precipitation Al2CuMg,Al3Zr phase with a small amount ofθphase precipitates,it is also trend to grow up.2026 aluminum alloy hot compressed specimens before and after heat treatment under different conditions of the micro-Vickers hardness values increasing basically with the lnZ decreasing.
|
PDF Full Text Request