Study of the Hot Workability of Light Alloys through Workability Simulation, Alloying and ECAE Process
博士 === 國立交通大學 === 機械工程系所 === 95 === Both titanium alloys and magnesium alloys have less hot workability than other loght-weight alloys. This research aimed to improve the hot workability of selected titanium alloy and magnesium alloy through workability simulation, alloying and equal channel angular...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2007
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| Online Access: | http://ndltd.ncl.edu.tw/handle/37481239757588812277 |
| Summary: | 博士 === 國立交通大學 === 機械工程系所 === 95 === Both titanium alloys and magnesium alloys have less hot workability than other loght-weight alloys. This research aimed to improve the hot workability of selected titanium alloy and magnesium alloy through workability simulation, alloying and equal channel angular extrusion (ECAE) process. To achieve the specification of forged Ti-6Al-4V ELI for medical implant, a uniformly distributed ��/�� microstructure must be obtained after hot forging process. Hot workability was simulated through processing map to demonstrate the dynamic behavior of material during forging process. The optimum process conditions were then adapted from the power dissipation map and the instability map. The results were confirmed via the microstructure that hot deformed by the optimum process conditions. The results also indicated that the processing map was influenced by the initial microstructure before deformation. The application of processing map for multi-passes deformation must be modified by using multi-maps according to the passes design. This research also studied the improvement of hot ductility of AZ31 magnesium alloy. Grain size in the microstructure dominates the ductility of AZ31. This work presented a novel approach for enhancing the grain refinement of magnesium alloy by adding Sc and Zr. Rolling and ECAE were performed to refine the grains. Experimental results indicated that adding 0.03~0.06 wt% of Sc and 0.05~0.15 wt% of Zr reduced the mean grain size of AZ31 to 2.47 �慆. The ductility of AZ31-0.15Zr-0.06Sc can be increased to 324 % at 300℃. Results of this study demonstrated that both Sc and Zr are important in controlling grain size and ductility.
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