鎂鋰合金板材沖壓成形性之研究

Formability of LZ Magnesium Alloy Sheets

廖志杰(Chih-Chieh Liao)

指導教授 ： 陳復國

國立臺灣大學/工學院/機械工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.10100

摘要

近年來，因要求輕薄短小的3C產業快速發展，鎂合金逐漸受到產業界的重視，加速了鎂合金的應用，目前用於沖壓製程之鎂板以AZ31為主，然因其原子結構屬於六方最密堆積(HCP)，在常溫的成形性甚差，必須加溫至200℃以上方具備良好之成形性。但藉由鋰元素之添加，增加了體心立方(BCC)之原子結構，由於BCC可供滑移的系統眾多，因此鎂鋰合金之常溫成形性較佳，可採用一般塑性加工方式成形。
本研究探討鎂鋰合金(LZ61、LZ91、LZ101)在常溫下之沖壓成形性，首先建立材料機械性質及成形極限曲線，以作為基本之成形性研究。同時為了探討鋰含量對成形性之影響，本研究亦進行相關之沖壓成形性實驗，包括CCV實驗、極限引伸比實驗、90° V形彎曲與最小彎曲半徑實驗，以了解鎂鋰合金在常溫之成形特性。在金屬成形過程中，潤滑劑是一個重要的影響參數，因此將針對引伸加工常用之潤滑劑探討其潤滑效果。鎂鋰合金除了應用在3C產品殼件外，音響喇叭之共振膜片亦是極具開發價值的產品，本研究將測試鎂鋰合金之阻尼係數，以了解其阻尼性質。針對上述之實驗結果將與AZ31常溫及高溫性質做比較，以了解鋰含量對於鎂合金材料性質之影響性。本論文之研究成果將可作為相關模具設計之重要依據

關鍵字

鎂鋰合金 ； LZ61 ； LZ91 ； LZ101 ； 沖壓成形性 ； CCV ； 成形極限 ； 阻尼係數

並列摘要

Due to its lightweight and high specific strength, magnesium alloys have been widely used for structural components. However, because of the hexagonal closed-packed (HCP) crystal structures, magnesium alloys show low ductility at room temperature, and require thermal activation to increase their formability. It is well known that ductility of magnesium alloys can be improved with addition of lithium which develops the formation of body centered-cubic (BCC) crystal structures. The BCC crystal structure gives rise to high formability at room temperature.
The formability of different magnesium-lithium alloy sheets, such as LZ61、LZ91 and LZ101, was investigated by conducting various experiments in the present study. Tensile tests and forming limit tests were first conducted to investigate the mechanical behavior and formability of magnesium-lithium alloys with various lithium content. CCV tests and cup drawing tests were also performed to examine the stamping formability at room temperature. The experimental results reveal that the formability is much improved with higher Li content. Since the friction coefficient is one of important parameters in a stamping process, friction tests were preformed with the use of different lubricants and without lubrication. The friction coefficients obtained from the friction tests suggest appropriate lubricants to be used in the stamping of magnesium-lithium alloy sheets. In addition, V-bend tests were performed
to examine the springback property and minimum bending radius of magnesium-lithium alloy sheets at room temperature. Except for structural components, magnesium-lithium alloys can also be used for loudspeaker diaphragms because of its higher internal damping loss. Damping tests were performed to examine the damping coefficient of magnesium-lithium alloy sheets and the results were compared with those obtained for aluminum alloys. The experimental results obtained in the present study provide the fundamentals for the stamping die design of forming magnesium-lithium alloy sheets.

並列關鍵字

magnesium-lithium alloys ； LZ61 ； LZ91 ； LZ101 ； stamping formability ； CCV ； forming limit ； damping ratio

參考文獻

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