| Summary: | 碩士 === 國立中山大學 === 材料與光電科學學系研究所 === 103 === In this study, friction stir processing was used to fabricate the ultrafine grained microstructure from AA7075-T6 plate, and then, the artificial aging was applied to improve the mechanical properties. In the observations, the grain size is refined to micron sized. the degree of re-solution is proportional to the cooling rate, which was significant influenced by traverse speed and cooling surrounding. The result also indicates the re-precipitate phenomena is controlled by the cooling rate. In high cooling rate case, the degree of re-solution is large, after the artificial aging, yield strength and ultimate tensile strength are 534±4 MPa and 629±3 MPa, elongation is 19±1 %.
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