Dynamic Impact Behaviour of 316L Stainless Steel under Various Temperatures
| Autor: | Wen-ZhenLuo, 羅文振 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 This study investigates the impact mechanical properties and microstructure of 316L stainless steel under strain rates ranging from 103 s-1 to 5×103 s-1 at temperatures of 25℃ to 800℃ by using split Hopkinson pressure bar tester. The relationship between mechanical properties and microstructure of the deformed specimen are discussed in terms of testing temperatures and strain rate. The experimental results indicate that the flow stress, work hardening rate, strain rate sensitivity and activation volume of 316L stainless steel all depend significantly on the strain, strain rate and testing temperature. For a constant temperature, the flow stress, work hardening rate and strain rate sensitivity increase with increasing strain rate, while the activation volume decreases. Conversely, for a constant strain rate, the flow stress, work hardening rate and strain rate sensitivity decrease with increasing temperature, while the activation volume increases. It is found that the impact deformation behaviour of 316L stainless steel can be accurately described using the Zerilli-Armstrong constitutive equation. Optical microscopy analyses reveal that slip bands within the grains are found to increase with increasing the strain rate and testing temperature. Microvoid nucleation and growth within shear band are evident during the fracture process. Scanning electron microscopy fractographic observations show that the fracture features are characterized by ductile shear fracture and that knobbly structure form with respect to the direction of maximum shear stress. Transmission electron microscopy structural observation shows that an increase of strain rate or a decrease of testing temperature leads to an increase of dislocation densities, twin densities, and the volume fraction of α’ martensite. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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