Effect of different rolling process on the mechanical properties of AZ31 alloy

• Main Authors: Da-Chen Khung, 龔大成
• Other Authors: Jian-Yih Wang
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/89995595672764020581

碩士 === 國立東華大學 === 材料科學與工程學系 === 97 === The purpose of this research is increasing mechanical properties of magnesium alloy by designing and combining different initial temperature for rolling method. The Mg-3%Al-1%Zn alloy and was added 1wt% Ca for Mg-3%Al-1%Zn alloy was investigated. The materials were rolled by different temperature rolling into plates from room temperature, 200℃ and 300℃ respectively. After rolling process, the plates were annealed at temperatures of 300℃.The purpose of the material is improving material mechanical properties that is combined static recrystallization and dynamical recrystallization to achieve completely fine-grian effect between rolling process. The results show that the samples rolled form room temperature possessed the dynamical recrystallization and produced the better grain refinement effect. And the succeeding annealing process only promoted grains rearrangement. The room temperature tensile test results was founded that ProcessⅠhas the best ultimate tensile stress is 307 MPa, however average grain size increased when rolling initial temperature elevated, ultimate tensile stress decreased result from grian growth. Otherwise, the 1wt% Ca additive was decreased average grian size of material. The recrystallization temperature of AZ31+1%Ca is above of as-extruded AZ31 in differential Scanning Calorimeter test, so that the microsturcture become fiber structure in different temperature rolling process. The optimum tensile strength is 355 MPa under ProcessⅠrolling process. The average grain size and tensile properties were founded that the AZ31+1%Ca was superior to not added Ca of AZ31 in subsequent different process. Between the annealing process, the grain growth condition and grain size difference is more apparent in AZ31 alloy. The room temperature tensile test was a little enhancement in elongation. The optimum elongation reached 13% under rolling at 300℃ with 80 % rolling reduction and succeeding annealed at 300℃. The optimum ultimate strength is 289 MPa with 80 % rolling reduction in ProcessⅠ. The grain growth is not apparent on the AZ31+1%Ca, and the microstructure could maintain to fine uniformly condition. The optimum elongation reached 27.3 % under rolling at 300℃ with 80 % rolling reduction and succeeding annealed at 300℃. The maximum tensile is 292 MPa under ProcessⅠ with 80 % rolling reduction. In the stamping formability test, the materials have better elongation under different rolling process and annealing. They have better formability too.