ZK60鎂合金顯微組織與機械性質研究

Microstructure and mechanical properties of ZK60 magnesium alloy

陳麒任(Chi-Jen Chen)

指導教授 ： 李雄

國立中央大學/工學院/機械工程學系/碩士(2008年)

摘要

本研究探討耐溫型鎂合金之顯微組織及機械性質。選取目前較受矚目之ZK60鎂合金（Mg-6%Zn-0.5%Zr）為研究對象，利用熱擠製、軋延等塑變加工，配合熱機處理製程技術，嘗試獲得微細晶粒的ZK60鎂合金板材，進而達到超塑性。
研究方法，實際進行方式，係由中科院之豎型直接激冷式（Vertical Direct Chill Type）連鑄機製作成8"之ZK60鎂錠，再於380℃高溫下擠製成為6mm之板材。以加熱之軋延機進行不同軋延率（20％、40％、及60％）、軋延溫度（300℃、350℃、400℃、450℃）、退火溫度等參數對片材顯微組織及機械性質的影響。
經實驗結果顯示當軋延率20％金相組織呈現纖維狀的組織且在晶粒內部發現少數的雙晶組織，當軋延率達40％雙晶現象更為明顯且有少數的動態在結晶沿高能量的晶界，60％時有更明顯的動態再結晶，其餘晶粒仍呈現嚴重的纖維狀結構，所以需進行靜態退火消除。當軋延溫度350℃經軋延率60％後在經265℃×16hrs以及365℃×1hr等退火後金相組織呈現細小且等軸晶粒其晶粒大小分別8.3μm及7.7μm，其抗拉強度分別為294.8Mpa及302Mpa。
最後將軋延溫度350℃的軋延率繼續提升到80％且在進行265℃×16hrs的退火處理後可獲得均勻經歷大小為3.7μm且極細的金相組織。

關鍵字

ZK60 ； 鎂合金

並列摘要

This research probes into the microstructure and mechanical properties on the heat resistance magnesium alloy . Choose the ZK60 magnesium alloy (Mg-6% Zn-0.5% Zr) relatively attracting attention at present research object. In order to obtain fine grain size on ZK60 magnesium alloy, making use of plastic deformation such as hot extrusion 、hot rolling etc plus TMT(thermo mechanical treatment) technique .
Experimental procedures , the alloy was prepared by Vertical Direct chill casting into an 8” ingot in Chung-Shan institute of science＆technology. It was then followed by an extrusion at 380℃to obtain a 6 ㎜ sheet material. This as-extruded state was processed next in various rolling reduction ratio（20％、40％、60％、80％）、rolling temperature (300℃、350℃、400℃、450℃) and annealing temperature to observe the affection of microstructure and mechanical properties on this alloy.
Shown by the experimental result , for rolling reduction of 20％, it is showed fiber structure and some twins within crystalline. for rolling reduction of 40％, it is showed much higher density of twins and dynamic re-crystallizing grain go along grain boundaries. for rolling reduction of 60％,it is showed much higher density of dynamic re-crystallizing. Other crystalline grain still present the serious fibrous structure. So we need to take it away by. After rolling temperature 350℃and rolling reduction of 60％ then followed by 265℃×16hrs and 365℃×1hr annealing , the grain size is 8.3μm and 7.7μm respectively, the ultimate tensile strength is 294.8Mpa and 302Mpa respectively.
Finally, for rolling temperature 350℃and rolling reduction of 60％ then followed by 265℃×16hrs annealing, a fine grain structure was obtained, the grain size of the structure is 3.7μm.

並列關鍵字

ZK60 ； magnesium alloy

參考文獻

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