臺灣博碩士論文加值系統

本實驗研究目的是希望藉由合金設計搭配熱機處理的方式提昇鎂合金成形性。選用Mg-4.5%Al-1.5%Zn之成分，試片先經過均質化處理之後，分別升溫至350℃與200℃進行不同軋延率之溫軋，而後進行退火處理。350℃軋延材在軋延時發生動態再結晶，產生晶粒細化的效果，之後進行退火有調整晶粒組織與再結晶的作用。室溫拉伸實驗由於軋延試片發生動態再結晶，因此延展率隨軋延率增加而提升，60%軋延率350℃退火之試片延展性最好可達25%，抗拉強度在軋延率80%時為310MPa為最好。高溫拉伸實驗中，150℃拉伸時延展率可以到達56%，但是當升溫至300℃時延展率只有小幅提升到85﹪。200℃軋延材軋延時不會發生動態再結晶，晶粒內部有明顯的雙晶與滑移帶產生，加工變形組織非常明顯，退火處理發生再結晶現象，晶粒細化尺寸小於10μm，也小於350℃軋延之再結晶晶粒尺寸。室溫拉伸實驗中，退火之後延展率大幅提升，軋延率20﹪350℃退火之試片延展性達到38%最好，抗拉強度在軋延率80%時為339Mpa最佳。高溫拉伸實驗中，150℃拉伸延展率與室溫拉伸相比沒有顯著提升，在300℃拉伸時，軋延材與250℃退火之試片伸長量可達127%與153%。

The purpose of this research is increasing formability of magnesium alloy by alloy design and heat treatment. The Mg-4.5% Al-1.5% Zn alloy was investigated. The homogenized ingots were rolled into plates atdifferent rolling reduction ratios under 200℃ and 300℃ respectively. After rolling process, the plates were annealed at temperatures of 250℃ and 350℃. The results show that the samples rolled at 350℃ possessedthe dynamical recrystallization, and the grain refinement is remarkable.And the succeeding annealing process only promoted grainsrearrangement. The room temperature tensile test results show theelongation increase as the reduction ratio increase. That is because thedegree of dynamical recrystallization is increasing as rolling reductionincreasing. The optimum tensile strength is 310MPa under 80% rollingreduction. Meanwhile, the optimum elongation is 25% after 60% rollingreduction and succeeding annealed at 350℃.The high temperature tensiletest results show that the optima elongations are 56% at 300℃, and 85%at 300℃, respectively. On the other hand, the samples rolled at 200℃didn’t show the dynamical recrystallization. The microstructure possesses heavily deformed slip band as well as twining. The recrystallizationoccurred after anneal treatment. The grain size is below 10μm, which issmaller than the samples rolled at 350℃. From the room temperaturetensile test results, the ductility was increased remarkably. The optimumelongation reached 38% under rolling at 200℃with 20% rolling reduction and succeeding annealed at 350℃. Meanwhile, the maximum tensile strength is 339 MPa under rolling at 200℃with 80% rolling reduction.
The 150℃ high temperature tensile test shows the elongation of samplesis similar to the room temperature test. However, the elongations of samples test at 300℃ as high as 127% and 153% after rolling at 200℃ only and succeeding annealing at 250℃, respectively.

第一章 前言…………………………………………………………1
第二章 文獻回顧……………………………………………………5
2-1 鎂合金簡介…………………………………………………5
2-2 鎂合金晶粒細化……………………………………………7
2-2-1 合金元素添加對鎂合金的影響…………………………8
2-2-2 熱機處理對鎂合金的影響………………………………9
2-3 金屬材料再結晶理論……………………………….....11
2-3-1 動態再結晶……………………………………………….14

第三章 實驗方法…………………………………………………23
3-1 材料準備…………………………………………………23
3-1-1 合金選擇與均質化處理…………………………………23
3-1-2 合金成分分析……………………………………………23
3-2 熱性質分析………………………………………………24
3-3 熱機處理…………………………………………………24
3-4 顯微組織觀察……………………………………………25
3-5 XRD晶體結構分析…………………………………………25
3-6 TEM試片製作與微結構組織分析…………………………26
3-7 機械性質測試……………………………………………26

第四章 結果與討論…………………………………………………37
4-1 鑄錠原材與均質化處理…………………………………37
4-1-1 顯微組織觀察……………………………………………37
4-1-2 合金成分鑑定與機械性質分析………………………….37
4-2 均質化AZ41鎂合金350℃軋延………………………38
4-2-1 軋延金相顯微組織觀察…………………………………38
4-2-2 退火金相顯微組織觀察…………………………………39
4-2-3 XRD繞射分析…………………………………………….40
4-2-4 硬度值分析………………………………………………41
4-2-5 TEM顯微組織觀察……………………………………….42
4-2-6 拉伸機械性質分析………………………………………43
4-3 均質化AZ41鎂合金200℃軋延…………………………44
4-3-1 軋延金相顯微組織觀察…………………………………44
4-3-2 退火金相顯微組織觀察………………………………….45
4-3-3 XRD繞射分析…………………………………………..46
4-3-4 硬度值分析……………………………………………….47
4-3-5 TEM顯微組織觀察……………………………………..47
4-3-6 拉伸機械性質分析……………………………………….48

第五章 結論………………………………………………………91

參考文獻……………………………………………………………93

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