| Creep age forming is a forming method combined aging and forming simultaneously by taking metal properties of creep. Fundamental creep aging research and creep aging at different technologies were carried out by selecting7055aluminum alloy in this thesis. The effects of different creep aging temper on the amount of creep deformation, the microstructure and properties were studied by using optical microscopy (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and other kinds of testing techniques. Then the creep age forming theory and the mechanism were analyzed, the following conclusions were obtained:(1)The creep aging behavior of7055aluminum alloy was revealed. As for the solid solution and quenched samples, In the first stage the creep aging mechanism is dislocation viscosity slip. In the second stage the creep aging mechanism is dislocation climb and Orowan mechanism.(2)The microstructure and properties evolution rule of creep aging7055aluminum alloy were illustrated. The η’precipitation phase of creep aging samples precipitate much more, much smaller and distributed more uniformly than those of artificial aging, therefore, the creep aging samples have much higher tensile strength and yield strength than those of artificial aging.(3)The influence of creep aging after pre-treated of7055aluminum alloy on the microstructure and properties were illustrated. The tensile strength and yield strength of pre-treatment samples are slightly smaller to those of solution treatment samples.The technology of T77temper creep aging of7055aluminum alloy was preliminary explored. The appropriate RRA treatment is120℃/24h preaging,150℃/8h retrogression,and120℃/24h re-aging,which led to tensile strength of642MPa,yield strength of623MPa,elongation of10.1%, Electric conductivity is38.6IACS%. |
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