Heat Treatment On The Microstructure And Mechanical Properties Of Alloy 6082, 6063

The effects of homogenization treatments and solution-ageing treatments on the6082aluminum alloy and6063aluminum alloy have been investigated by using hardness and electrical conductivity measurement, optical microscope (OM), X-ray diffraction (XRD), scanning electronic microscope (SEM), energy dispersive spectrum (EDS) and transmission electron microscopy (TEM). The results show that:(1) Supersaturated solid solution of6082aluminum alloy changes into equilibrium Mg2Si phase at490-510℃; equilibrium phases are dissolved into matrix when the homogenization temperature increases; There is only spherical α-Al(MnFe)Si phase in the aluminum after annealing at560℃for6h, and dispersive α-Al(MnFe)Si particles deposit in the alloy during homogenization. The6082aluminum alloy is appropriate to be homogenization treatment at560℃for6h.(2) When the6082alloy is annealing high temperature, the eutectic morphology of precipitates disappear gradually, acicular β-AlMnFeSi phase transforms to spherical a-Al(MnFe)Si phase and the ratio of (Mn+Fe)/Si in AlMnFeSi phase increases.The precipitates is changed into spherical α-Al(MnFe)Si phase after annealing at560℃for6h.(3) During the homogenization treatment of6063alloy, the eutectic morphology of precipitates and the interdendritic segregation disappear gradually with increasing annealing temperature or keeping time. Supersaturated solid solution decomposed equilibrium Mg2Si phase at495℃for6hours. When the homogenization treatment temperature increased at555℃for6hours, Mg2Si phase dissolved into matrix and acicularβ-Al9Fe2Si2phase transformed to spherical α-Al12Fe3Si phase completely, and some submicron dispersive AlFeSi and AlFeCrSi particles deposited in the alloy.(4) The proper homogenizing process of6063alloy is at555℃for6h.(5) The6082alloy is kept at160℃for half an hour for pre-ageing first, and then kept at175℃for4hours for the ageing treatment after kept at nature temperature for48hours. The coherency β" phases deposited in the alloy, and the strength of the alloy reaches maximum.(6) The mechanical properties of two-step aged6063aluminum alloy get much better than that of single aging treatment.