摘要

本論文主旨在探討GTAW銲接參數對鋁鋅系列鎂合金銲接性之影響，實驗方法採用不添加填料之情況下，針對AZ31及AZ80鎂合金進行對接銲與異種鎂合金(AZ31-AZ80)接合。本研究範圍包括銲道型態、顯微組織及機械性質之分析。
研究結果發現，AZ31及AZ80鎂合金以GTAW對接銲時，其銲道寬度係隨著熱輸入量增加而增加；銲道深寬比亦隨著熱輸入量之增加而有增加之趨勢，其中以AZ80鎂合金之銲道寬度均較寬於AZ31鎂合金。
顯微組織觀察結果發現，銲道晶粒尺寸係隨著熱輸入量的增加而有增加的趨勢；在晶界析出之第二相則隨著熱輸入量之增加而有降低之趨勢。
機械性質試驗包括微硬度試驗與拉伸試驗，研究結果顯示，銲件之機械強度係隨著熱輸入量之增加而降低，其中AZ80鎂合金銲後之機械性質均優於AZ31鎂合金與異種鎂合金銲件；且三種銲件之拉伸破斷面皆屬於脆性破壞型式。

關鍵詞：鋁鋅系列鎂合金、銲接性、異種接合

Abstract

The study to investigate the effect of welding parameters on the weldability of AZ magnesium alloys . A butt welding without filler metal of AZ31, AZ80 and dissimilar matel (AZ31-AZ80) joint by GTAW. It includes three parts. The first part was the semblance of weld, the second part was the microstructure observation, the third part was the mechanical properties of weldment.
From the result of Mg alloys by GTAW, the weld width and aspect ratio both increase with increasing input energy. Especially, the weld width were wider in AZ80 than AZ31 Mg alloy.
From the microstructure observation, the formation of larger grain with increasing input energy. However, the number of secondary phase increases with decreasing input energy.
Mechanical tests includes microhandness tests and tensile tests, the study results indicate that the mechanical properties of weldment decreases with increasing input energy. From the results of mechanical tests, the mechanical strength of AZ80 were higher than AZ31and dissimilar joint weldment. The brittle fracture surface was observed in all tensile tested specimens.

Keywords: Al-Zn magnesium alloy, wldability, dissimilar joint.

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