Study on High Temperature Mechanical Properties of ZK60 Magnesium Alloy by Controlling the Microstructure under Different Rolling Process
| Autor: | Ta-Chien Cheng, 鄭達謙 |
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| Rok vydání: | 2010 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 98 In this study, the high temperature mechanical properties of thermal mechanical treated commercial ZK60 alloy were investigated. The research is performed at 200℃ and 300℃ to understand its high temperature mechanical properties. Thermal mechanical treatments were performed at different temperatures of 200℃, 400℃, and room temperature with different rolling reduction. The results show the equiaxed or fibrous structures were obtained after different thermal mechanical treatment, and consequently created an effect on the high temperature mechanical properties. The deformation mechanism of ZK60 at 200℃ is power law creep under strain rate from 1×10-2s-1 to 1×10-4s-1. At 300℃, the deformation mechanism under strain rate 1×10-2s-1 is power law creep; under strain rate 1×10-3s-1 the deformation mechanism is grain boundary sliding; under strain rate 1×10-4s-1 the deformation mechanism is diffusion flow. In this research the equiaxed structure of ZK60 alloy shows maximum elongation of 856.2% tested at 300℃ and under a strain rate of 1×10-4s-1. On the contrary, ZK60 alloy with fibrous structure will produce uniform dynamic recrystallization (DRX) in the tensile gauge during power law creep deformation. This phenomenon improves the elongation and creep life. Furthermore, ZK60 alloy with fibrous structure possesses superplasticity and keeps an elongation of 535.2% tested at same condition. From the microstructural evaluation, ZK60 alloy with fibrous structure produced the dynamic recrystallization during the high temperature tensile test at 300℃, and consequently showed the superplasticity. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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