6061鋁合金於累進式背擠製成型研究

鄭名翔(Ming-hsiang Cheng)

指導教授 ： 葉維磬

國立中央大學/工學院/機械工程學系/碩士(2015年)

摘要

由劇烈塑性變形(Severe plastic deformation, SPD)方法達到超細晶粒(Ultrafine-grained, UFG)材料已被廣泛研究，本文採取由Fatemi-Varzaneh[20]等人提出的累進式背擠製(Acumulative back extrusion, ABE)於室溫對6061鋁合金加工。透過實驗與模擬，搭配不同的沖頭比(Deformation ratio,DR)與內沖頭行程(Die stroke,DS)，並配合硬度、微觀結構與有限元素模擬分析，探討ABE擠製過程的機制，與不同實驗參數造成的效應。經由有限元素模擬分析與實驗結果比較獲得良好的一致性，DR與DS會影響材料加工硬化與硬度均勻程度的變化，而本研究中能夠產生奈米等級的晶粒，但大部分晶界仍保持在低角度，顯示在仍無法達到超細晶粒的要求。

關鍵字

6061 ； 擠製

並列摘要

To reach the ultrafine-grained(UFG) material from severe plastic deformation(SPD) method has been widely investigated.The present work used the AA60
61 in the room temperture processing of accumulative back extrusion(ABE) that
was one of the SPD techniqus was originally proposed by Fatemi-Varzaneh[20].
To investigate the mechanics of the processing of the ABE using the experi-
ment and the finite element method(FEM) with different deformatio ratio(DR),
Die stroke(DS) and pass number.Then,the microhardness and the microstructure
were utilized to study with the effective strain(ES) and shear strain(ES). Compa
ring the FEM and experimental results showed good agreement in the ES conto-
ur and microhardness. The DR and DS both has the great effect in the mechanic-
al properties of the workpiece.Althrough the part the grain size has high ES thro-
ugh one to three pass all can reach the nanoscale in the microstructure result,the
most of grain boundaries still remained low anglar grain boundry.It means the high stacking fault energy of AA6061 through ABEed processing at room temp-
erture still can’t satisfied with the UFG.

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