| Summary: | 碩士 === 中華大學 === 機械工程學系碩士班 === 98 === A series of experiments was performed using stepwise pressurization profiles for gas blow forming of fine-grained magnesium alloy AZ31B-O sheet, sheet thickness of 0.6mm, The average grain size was about 5 ~ 6μm. The magnesium alloy AZ31B-O has better plastic deformation in high temperature, and the studies gas blow forming of decreasing forming time, with the rapid pressurizing profiles of feasibility. Gas blow forming was carried out at temperatures of 300, 370 and 420℃ using various pressurization profiles. The stepwise increment pressurization profiles, with the experimental of forming in 90 and 160 seconds to complete. The studies shape of formability of free bulging test, thickness, ultimate elongation and grain size change in multiaxial strain state of deformation profiles by AZ31B-O sheet. The results were analyzed, various temperatures and strain rate for influence on the forming parameters. The results show, the pressurization conditions was feasible of decreasing forming time, and slip system produced a new pole and increasing plastic in higher temperature. Then was pressure of decreased in gas blow forming. In the present work the dynamic recovery is less obvious, became the materials of the major factors influencing is work hardening at temperature of 300ºC. The temperature of 370 and 420ºC, they had similar between the formability , and show a more uniform deformation in a low strain rate pressurization, then static annealing has easily effect to grain growth in a high temperature of 420℃.
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