7XXX系含鈧鋁合金的顯微結構與機械性質之分析; Microstructure and Mechanical Properties of 7XXX Series Aluminum Alloys with Scandium

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Title:	7XXX系含鈧鋁合金的顯微結構與機械性質之分析;Microstructure and Mechanical Properties of 7XXX Series Aluminum Alloys with Scandium
Authors:	陸仁凱;Jen-Kai Lu
Contributors:	機械工程研究所
Keywords:	鈧;7XXX系鋁合金;scandium;7XXX series aluminum alloys
Date:	2006-07-05
Issue Date:	2009-09-21 11:58:18 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	鋁合金因為比強度高、重量輕、高導熱(電)性、良好的延展率與易於加工成形，而被廣泛的利用。鋁合金添加Sc以提高機械性質之研究早年經蘇聯人提出，近年來逐漸受到重視，本實驗用材料亦已成功應用在腳踏車車架、高爾夫球杆頭等實際民生用品上。本實驗以鈑材的Al-7.9Zn-2.5Mg-2.3Cu合金，和棒材的Al-6.0Zn-2.0Mg合金為對象，均添加~0.1wt.%的Sc和~0.1wt.%的Zr。鈑材經輥軋和棒材經等通道彎角擠製方式，鈑材改變「軋延率」、「拉伸溫度」，棒材改變「擠製方位」、「擠製道次」等參數，期望能提升材料強度並增加7XXX系含鈧鋁合金運用的廣泛性。由實驗結果可知在添加~0.1wt.%的Sc後，常溫抗拉強度約可提升30MPa，降伏強度約可提升25MPa，延伸率亦可從5%提升至12.3%。鈑材在400℃時有最佳延伸率353.9％；棒材在400℃時有最佳延伸率為329.8％，各項機械性質皆獲得一顯著量的提升。鈑材當R=40%時，擁有最大的抗拉(583MPa)、降伏(474MPa)強度值和最佳的延性；當R=60%時，強度反而下降~80MPa。在300~500℃下，R=20％的最佳延伸率~395％；R=40％的最佳延伸率~555％，雖然R=20％比R=40％有稍高的高溫機械強度，但延伸率卻大幅降低1.4倍。棒材透過EACE (Rote A、C1~C3)擠形，經C1的晶粒尺寸約為50μm；經C3的晶粒尺寸約為40μm，可使晶粒細化約20％。當透過EACE (Rote Bc、C1~C8)擠形，經C1的晶粒尺寸約為50μm；經C6的晶粒尺寸約為15μm，可使晶粒細化約70％。 Aluminum alloys have been generally used because of its opposite strength, light weight, high heat and electric conductivity, superior ductility and easily to manufacture. One's early years, Soviet bring up that aluminum alloys have perfect mechanical properties when adding scandium into alloys. This approach has more and more emphasis recently and is used for the frame of bicycles, the head of golf club and so on. The experiment adopts Al-7.9Zn-2.5Mg-2.3Cu alloy and Al-6.0Zn-2.0Mg alloy which are all added about 0.1wt.% scandium and about 0.1wt.% zirconium. Metal plate is processed by rolling and metal bar is processed by equal channel angular extrusion. Metal plate changes the rolling reduction ratio and changes the temperature of elongation. Metal bar changes the direction and the frequency of extrusion. By way of changing these parameters, we aspect this method can promote the strength of materials and improve the breadth of 7XXX series of aluminum alloys which are added scandium. The experiment result exhibit that the tensile strength can promote about 30 MPa, yield strength can promote about 25MPa and elongation can promote from 5% to 12.3% at room temperature when adding about 0.1wt.% scandium into alloys. The excellent elongation of plate is 353.9% and the excellent elongation of bar is 329.8%. We can know that all of the mechanical properties are obvious be promoted when the temperature is 400℃. When R=40%, the maximum tensile strength of metal plate is 583Mpa, the maximum yield strength is 474MPa and the material has the best elongation. When R=60%, the tensile strength instead of declining about 80MPa. The temperature of all tensile tests are below 300℃ to 500℃. When R=20％, the excellent elongation is about 395％. When R=40％, the excellent elongation is about 555％. Although R=20％ has better mechanical strength than R=40％, but the elongation is obvious lower 1.4 times than R=40％. The bar is used by ECAE. When the extrusion coefficient is Rote A, the grain size is about 50μm after C1 extrusion and is about 40μm after C3 extrusion. After that, the grain size can be thinned down about 20％. When the extrusion coefficient is Rote Bc, the grain size is about 50μm after C1 extrusion and is about 15μm after C6 extrusion. After that, the grain size can be thinned down about 70％.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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