| Summary: | 碩士 === 國立高雄應用科技大學 === 機械工程系 === 105 === In this study, we investigate the mechanical properties and the microstructural evolution of the three aluminum alloys (Aluminum alloy 2017, 5083 and 7050). It used Material Testing System (MTS) and Split-Hopkinson Pressure Bar (SHPB) to examine the mechanical properties of the three aluminum alloys at strain rate of 10 -3 ~10 -1 s -1 and 2×10 3 s -1 ~ 4×10 3 s -1 ,respectively. After quasi-static and SHPB testing, this study also examines the material hardness by Vickers Hardness Tester and Rockwell Hardness Tester. The experimental results indicate that the plastic flow stress and strain rate sensitivity coefficient of three aluminum alloys are changed with variations of strain and strain rate. Both of the plastic flow stress and strain rate sensitivity coefficients are increasing with the increase of strain and strain rate. Moreover, the hardness of three aluminum alloys is also increasing with strain rate. After materials testing, the surface features of the three materials are observed by using optical microscope, which could be found that the appearances of their crystal organizations became larger with strain and strain rate.
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