Announcement for Downloading full text filePlease respect the Copyright Act.
All digital full text dissertation and theses from this website are authorized the copyright owners. These copyrighted full-text dissertation and theses can be only used for academic, research and non-commercial purposes. Users of this website can search, read, and print for personal usage. In respect of the Copyright Act of the Republic of China, please do not reproduce, distribute, change, or edit the content of these dissertations and theses without any permission. Please do not create any work based upon a pre-existing work by reproduction, Adaptation, Distribution or other means.
URN etd-0720105-132528 Statistics This thesis had been viewed 2903 times. Download 1166 times. Author Yu-Sheng Yu Author's Email Address firstname.lastname@example.org Department Materials Engineering Year 2004 Semester 2 Degree Master Type of Document Master's Thesis Language English Page Count 150 Title A Study on the Strain Softening and Anneal Hardening in Zn-22 wt％ Al Alloy Keyword Zn-22 wt.﹪Al strain sofening anneal hardening anneal hardening strain sofening Zn-22 wt.﹪Al Abstract In this study thermomechanical processings were applied to a Zn-22 wt.% Al alloy to produce fine- and coarse-grained structures for the strain softening and anneal hardening studies. The microstructure, hardness and compression curve of Zn-22 wt.% Al alloy were studied by using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), microhardness measurements and compression tester. The results showed the occurrence of a strain softening phenomenon in the Zn-Al alloy in the temperature range from -10℃ to 250℃ and an anneal hardening behavior in the softened Zn-Al alloy upon high temperature annealing. The mechanism of the strain softening behavior was found to be the DRX-induced softening during hot working, which can be facilitated by the formation of ultra-fine β grains with high-angle-boundaries; the mechanism of the anneal hardening behavior, on the other hand, was the annihilation of the ultra-fine β grains by a high temperature grain coarsening treatment to retard the occurrence of the DRX-induced softening and to restore the “normal strength” of the alloy.
A composite stress-strain curve model was proposed in this study to resolve the mechanism of strain softening in the Zn-22 wt.％ Al alloy. By using this model detailed informations regarding to the deformation and the DRX (i.e. the strain softening behavior) in individual α and β phases were disclosed from the experimental compressive stress-strain curve.
Advisor Committee Chih-Fu Yang - advisor
Jien-Wei Yen - co-chair
Liou-Ho Chiu - co-chair
Ruri-Kai Chen - co-chair
Wen-Shiung Wang - co-chair
Files Date of Defense 2005-07-15 Date of Submission 2005-07-20