臺灣博碩士論文加值系統

　　5083(4.3wt.%Mg)鋁合金擁有質輕、耐蝕性佳、比強度高等特性，為加工硬化型鋁合金，常運用在交通工具上，近來也用來作為製作LCD玻璃基板之加熱基板。因此在應用上除了會遇到接合問題外，也會遭遇在不同溫區下操作使用的考驗。故本實驗對5083壓延退火材(O材)施以摩擦攪拌製程(Friction Stir Process，FSP)處理，並在固定初始應變速率條件下(1.67×10-3 sec-1)，探討其攪拌區域在不同溫度下( RT~ 450℃)之拉伸性質表現。
　　經FSP後(FSP材)，晶粒由原本呈扁平狀，細化為平均晶粒徑9μm之等軸晶。分別將O材及FSP材進行拉伸試驗後發現，由工程應力-應變曲線之型態差異可分為三個溫度區域︰低溫區(RT~100℃)、中溫區(150℃~ 250℃)、高溫區(300℃~ 450℃)。低溫區曲線特徵為具有鋸齒狀抖動之動態應變時效(DSA)效應；高溫區曲線特徵為波浪狀上下抖動之動態再結晶(DRX)現象；中溫區曲線鋸齒狀抖動消失，平滑中帶有些微抖動，研判為DSA及DRX之過渡區。在低溫區中，相同溫度時FSP材之臨界應變量低於O材，且室溫時FSP材之應力降大於O材，顯示室溫時之DSA現象在FSP材中較顯著。
　　拉伸性質方面，O材及FSP的拉伸性質隨溫度變化之趨勢大致相同，降伏強度在200℃前持平，隨後隨溫度上升而下降；抗拉強度則在100℃前大致相同，隨後隨溫度升高而降低；均勻延伸率先升後降在100℃時達最高點；總延伸率在各溫區皆為FSP材優於O材，100℃前持平，之後隨溫度上升而上升，FSP材在400℃以上甚至出現高於200%以上之總延伸率。

　The 5083 aluminum alloy (Al-4.3Mg) is widely used for many application in automotive, marine, aircraft body sheet due to its excellent combination of strength, corrosion resistance, weldability and low cost. Nowadays, it is also used in the LCD industry as the heating plate of the LCD glass substrate. Therefore, besides the welding problem, it will also encounter the trial of being used under different temperature condition.
　In this study, annealed aluminum alloy of 5083, called 5083-O, is processed by friction stir process (FSP). 5083-O and 5083-FSP are both tested by tensile test at different temperature (from room temperature to 450℃), and by constant initial strain rate (1.67×10-3 sec-1). The tensile properties of stirring zone at different temperature will be discussed.
　In the microstructure of 5083-FSP, the stirring zone has equal-axial recrystallized grains in contrast with the elongated grains in 5083-O. After the tensile test, we define three temperature regions owing to the difference between the engineering stress-strain curves: Low Temperature (LT, RT~100℃), Intermediate Temperature (IT, 150℃~ 250℃) and High Temperature (HT, 300℃~ 450℃). In LT, the curves are characterized by the serrated flow curve due to the effect of dynamic strain ageing (DSA); In HT, the curves are characterized by the wavy flow curve as a result of the occurrence of dynamic recrystallization (DRX). As to IT, the serrated flow curve disappears in this region, the curve is smooth with a bit of fluctuation; therefore, IT might be the transition area between DSA and DRX. In LT, the critical strain of 5083-FSP is lower than 5083-O at the same temperature. At room temperature, the stress drop of 5083-FSP is higher than that of 5083-O. It indicates that, DSA effect is much more obvious in 5083-FSP at room temperature.
　The tensile properties of 5083-O and 5083-FSP have similar tendency toward the variation in temperature. The yield stress (YS) and ultimate tensile strength (UTS) decrease with the increasing temperature. but YS is very near before 200℃and UTS is very near before 100℃. The uniform elongation (UE) increases with increasing temperature before 100℃ and decreases with increasing temperature after 100℃. The total elongation (TE) is near before 100℃ and after that TE increases with increasing temperature. 5083-FSP even shows high elongation over 200% at temperature higher than 400℃.

摘要 I
Abstract II
總目錄 IV
圖目錄 VI
表目錄 VIII

第一章 前言 1

第二章 文獻回顧 3
2-1 加工硬化型鋁合金及Al-Mg系(5083)鋁合金介紹 3
2-2 摩擦攪拌銲接/摩擦攪拌製程 3
2-3 動態應變時效 4
2-3-1 鋸齒狀流變型態 5
2-3-2 動態應變時效現象與影響因素 5
2-4 動態再結晶 7

第三章 實驗步驟與方法 11
3-1 實驗用材料 11
3-2 摩擦攪拌製程 11
3-3 拉伸性質測試 12
3-4 微觀組織特性觀察及硬度測試 12
3-4-1 微觀組織 12
3-4-2 微硬度測量 13
3-4-3 XRD分析 13

第四章 實驗結果 21
4-1微觀組織特徵觀察 21
4-2拉伸特性探討 22
4-2-1 攪拌製程前後之拉伸次表面及破斷面觀察 22
4-2-2 5083鋁合金經摩擦攪拌後之拉伸變形行為 23
4-2-3 摩擦攪拌製程對動態應變時效影響 24
4-2-4 摩擦攪拌製程對動態再結晶現象影響 24

第五章 討論 49
5-1 摩擦攪拌前後微觀組織及硬度 49
5-2 低溫區(＜100℃)拉伸性質之摩攪拌效應探討 50
5-3 中溫區(150℃∼250℃)拉伸曲線探討 51
5-4 高溫區(＞300℃)拉伸曲線之摩攪拌效應探討 52

第六章 結論 63

參考文獻 64

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