| Summary: | 碩士 === 南臺科技大學 === 機械工程系 === 107 === In this paper, the effects of differentheat treatment processes on the microstructures and mechanical properties of the AA 7050 aluminum alloy under different heat treatment condition were investigated by optical microscope, X-ray diffraction analyzer, scanning transmission electron microscope, Rockwell hardness tester, wear resistance tester and tensile test machine.The heat treatment process includes artificial aging and Retrogression and Reaging treatment, and avoid excessive grain growth , the artificial aging temperature is selected below the recrystallization temperature of the aluminum alloy. Then discuss the influence of microstructure and mechanical properties.
According to the research results of this thesis, the samples subjected to aging, recovery and aging, and T6I6 aging treatment can effectively improve the hardness and tensile strength, and can be kept in the unheated sample regardless of the heat treatment process. A fairly close ductility, especially as a result of the heat treatment of T6I6, maintains the same ductility as the unheated test piece.The experimental data of this thesis shows that the AA7050 aluminum alloy is solution treated in an environment of 475 ° C for one hour, and then subjected to water quenching, and then preheated at 140 ° C for 3 hours, and then applied at 60 ° C for 24 hours. The low temperature aging of the hour, and finally the application of the sample held at 140 ° C for 3 hours can obtain the best mechanical properties.
In the observation of the transmission electron microscope, fine and dense precipitates were evenly dispersed in the base of the sample treated with T6I6 heat treatment. According to the analysis results of EDS, the precipitates were common strengthening phases of general 7 series aluminum alloys. η' (MgZn2). It can be seen that the mechanical properties of the 7050 aluminum alloy can be effectively influenced according to the density and size of the precipitate.
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