| Summary: | 碩士 === 大同大學 === 材料工程研究所 === 90 === Most of the documents of plastic forming at present disclose the mechanical properties of extruded Mg alloys. The amount of relevant information from the plastic forming by rolling the Mg sheets is still insufficient. As such, this study aims to explore the microstructural evolution and property change in two common wrought Mg alloys, namely AZ31 and AM30, in the process of thermomechanical treatments. The effect of grain refine was also examined in this study.
The results showed that dynamic recrystallization was observed in the AZ31, AZ31+, AM30 and AM30+ Mg alloys warm rolled at 150℃ to strains exceeded 0.25 when tested at temperatures of 250℃ or higher. The recrystallized grain size in the Mg alloys was found decreased with an increase in the applied rolling strain. Most of the maximum tensile elongation data found in the various warm rolled Mg alloys occurred at the test temperature of 250℃due to the occurrence of dynamic recrystallization, and the tensile elongation at 250℃ increased with the applied rolling strain. A comparison of the dynamic recrystallized grain size in Mg alloys with grain refiner (i.e. AZ31+ and AM30+) to those without (i.e. AZ31 and AM30) showed that the speed of grain growth occurring in AZ31+ and AM30+ was slower than that in AZ31 and AM30 to result in a finer grain structure.
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