| Summary: | 碩士 === 國立成功大學 === 機械工程學系 === 88 === The purpose of this study is to investigate the dynamic plastic behavior of 60Sn-40Pb solder under various temperatures and strain rates by means of a split Hopkinson bar. Tested temperatures were obtained by enclosing the specimen in a clam shell heating furnace and cooling device. Cylindrical specimens were tested at strain rates of 1000s-1, 2000s-1 and 4000s-1, and at temperatures of -40℃, 25℃ and 120℃. Optical and scanning electron microscopy analyzed fracture and microscopic characteristics. A constitutive equation is used to describe the dynamic plastic behavior of the material. The experimental results show that temperature and strain rate have an obvious effect on the mechanical properties of the material. Flow stress increases with strain rate, but decreases with temperature. The work-hardening rate, strain rate sensitivity, activation volume and temperature sensitivity change with strain, strain rate and temperature levels. Microscopic observation shows that microcrack density and tin particle deformation degree increases with strain rate and temperature. Fracture occurs at 120℃ at a strain rate of 4000s-1. Comparison of this study’s experimental results with the constitutive equation of Kobayashi & Dodd shows excellent agreement.
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