| A heat treatment process of aluminum alloy has been proposed in this paper which join vibration aging in the initial stages of thermal aging of material. In this new heat treatment method, the residual stress has been reduced. In the same time, the changes of dislocation and the crystal lattice distortion in the material can be used to control the precipitation of the second phase and improve the performance of material. Take Al-5.2Cu-0.43Mn alloy as an example, analysis determination techniques such as hardness test, tensile test, constant temperature immersion method, conductivity tests, polarization curve, optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), hole-drilling method of measuring residual stress has been used to research the influnce of thermal vibration aging technology on the precipitation process of the second phase and grain boundary precipitation. The conclusions are summarized as follows:(1) A larger residual stress of material obtained in the solution-quenching stage will lead to the precipitate orientation of theta"(Al2Cu) phase. Dislocation produced by micro plastic deformation in the thermal vibration aging will induce the heterogeneous nucleation of theta" phase, improve its nucleation rate, refinement its precipitate size and restrain the effect of stress orientation.(2) In the experimental conditions of this paper, the aging technologe of thermal vibration aging with-40-80MPa/83HZ/40min can reduce the residual stress of peak aged material from0.86Rp0.2to0.28Rp0.2, increase ultimate tensile strength by about5%and elongation by about25%, and shorten the peak aging time more than1times.(3) Not only the precipitation of second phase has been promoted, but also the boundary precipitates are balling in the thermal vibration aging. In the mean while, conductivity of the material has been reduced, the intergranular corrosion resistance performance of the material has been improved. |
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