本文針對鋁合金及鎂合金棒材之熱間擠製進行解析及實驗之研究。藉由模具傾斜角之製作使擠錠在模具內橫斷面之流速不均及材料之應變、應變率分佈不同。在模具中增添一平行道口及傾斜角之設計，使得表層部位微結構晶粒變小，因而獲得表面硬度較高之材料。本研究之目的為以不同模具之傾斜角度進行擠錠之熱間擠製加工，用以製作不同梯度機械性質之材料。首先，進行擠製模具之不同傾斜角設計，運用有限元素法在模具之軸承面出口處分析溫度、等效應變及等效應變率分佈情形。另外亦進行擠製實驗，鎂合金經過擠製後以光學顯微鏡位於成品之橫斷面處作金相觀察及硬度試驗，得知模具之傾斜角為15°時可得到較小之晶粒及較高之硬度，在中心範圍之晶粒大小為17.2μm，而硬度為68.2 HV；在邊緣處之晶粒大小為4.1μm，而硬度為83.8HV。

This study focused on analysis and experiment of hot extrusion of aluminum and magnesium alloys, an extrusion die with an inclination angle leads to non- uniform velocity distribution at the cross-section of the die, and results in different strain and strain rate distributions. This kind of design can make the grain size at the material surface smaller and get a material with larger surface hardness. This study aims to conduct hot extrusion with different die inclination angles, and obtain a material with gradient micro-structures. At first, die with different inclination angles are designed, and the temperature at the die exit and effective strain, effective strain rate distributions are discussed using the finite element analysis. At last, aluminum and magnesium extrusion experiments are conducted and the micro-structures of the materials are observed to understand the effects of the die inclination angles at 15 degrees on the grain size distribution and hardness test at the cross-section of the material. The grain size is about 17.2μm at around center of the cross-section and hardness is about 68.2HV. The smallest grain size is 4.1μm at the edge of the cross-section and the highest hardness is 83.8HV.

摘要 xiii
Abstract xiv
第一章 緒論 1
1-1 前言 1
1-2 擠製加工簡介 2
1-2-1 直接擠製法 2
1-2-2 間接擠製法 2
1-2-3 擠製加工條件對擠製性能之影響 4
1-3 文獻回顧 5
1-3-1 不同加工方式製作具有梯度之機械性質材料 5
1-3-2 不同加工方式對材料之晶粒細化影響 5
1-3-3 不同加工方式對梯度複合材料之影響 6
1-4 本論文之研究目的與架構 7
第二章 鋁合金A6061有限元素分析 9
2-1 鋁合金A6061熱間壓縮試驗 9
2-2 擠製分析之模具設計及參數設定 14
2-3 擠製負載分析 15
2-4 橫斷面半徑與模具位置之關係 16
2-5 不同傾斜角之溫度分析 17
2-5-1 不同傾斜角位於橫斷面半徑（r）之溫度分佈 17
2-5-1 不同傾斜角位於軸承面（x＝0mm）出口處之溫度分佈 19
2-6 不同傾斜角之等效應變率分析 20
2-6-1 不同傾斜角位於橫斷面半徑（r）之等效應變率分佈 20
2-6-2 不同傾斜角位於軸承面（x＝0mm）出口處之等效應變率分佈 21
2-7 不同傾斜角之等效應變分析 22
2-7-1 不同傾斜角位於橫斷面半徑（r）之等效應變分佈 22
2-7-2 不同傾斜角位於軸承面（x＝0mm）出口處之等效應變分佈 24
第三章 鎂合金AZ31有限元素分析 25
3-1 擠製分析之模具設計及參數設定 25
3-2 不同傾斜角位於軸承面出口處（x＝0mm）之模擬分析 28
3-2-1 傾斜角5°之模擬分析 28
3-2-2 不同傾斜角之模擬分析 29
3-3 鋁合金及鎂合金解析結果之比較 32
3-4 鎂合金之不同擠製參數之模擬分析 35
3-4-1 不同傾斜角之模擬分析 36
3-4-2 不同傾斜角位於橫斷面半徑（r）之等效應變及等效應變率分析 37
3-4-3 不同的平行部長度（L1）及不同的傾斜角長度（L2）之比較 40
3-4-4 不同L1及L2位於橫斷面半徑（r）之等效應變及等效應變率分析 41
3-4-5 不同的擠製比之模擬分析 43
第四章 擠製加工分析及實驗 44
4-1 實驗規劃 44
4-1-1 擠製加工實驗 45
4-1-2 金相觀察規劃 46
4-2 鋁合金之實驗結果 49
4-2-1 鋁合金成分及特性 49
4-2-2 鋁合金熱處理之基本概論 50
4-2-3 鋁合金解析值與實驗值荷重之比較 52
4-2-4 鋁合金不同傾斜角之前段小擠錠（B1）與成品（P1）之金相觀察 55
4-2-5 鋁合金不同傾斜角之前段小擠錠（B1）與成品（P1）之晶粒量測 62
4-2-6 鋁合金不同傾斜角之後段大擠錠（B2）與成品（P2）之金相觀察 66
4-2-7 鋁合金不同傾斜角之後段大擠錠（B2）與成品（P2）之晶粒量測 74
4-3 鎂合金之實驗結果 77
4-3-1 鎂合金成分及特性 77
4-3-2 鎂合金變形之基本定義 79
4-3-3 鎂合金解析值與模擬值荷重之比較 79
4-3-4 鎂合金不同傾斜角之金相觀察 81
4-3-5 鎂合金不同角度之晶粒量測 89
4-3-6 鎂合金不同傾斜角之硬度試驗及硬度殘留面積分析 93
第五章 結論 101
5-1 鋁合金之有限元素解析及實驗 101
5-2 鎂合金之有限元素解析及實驗 101
5-3 鋁合金與鎂合金之解析結果比較 102
5-4 鎂合金之不同擠製參數結果比較 102
5-5 未來展望 103
參考文獻 104

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