A Study Characteristic on AZ80 Magnesium Alloys for TIGWelding and Heat Treatment

指導教授：蔡德昌 博士[[abstract]]本研究主要目的為探討 AZ80 鎂合金之銲接性質，以TIG 氬銲銲接在相同電壓與電流下進行對口銲接，銲件藉由回火熱處理後，以觀察AZ80 鎂合金顯微組織與機械性質之變化。實驗結果所示，由 X-ray 繞射分析顯示 AZ80 鎂合金銲件經過回火熱處理會有 β 相（Mg17Al12）析出，而 AZ80 鎂合金組織中有α-Mg基地相與 β 固溶相的組合。銲件顯微組織經回火熱處理後基地組織中其α相及 β 相分率會隨著回火溫度及時間而改變，隨著回火溫度與回火時間的增加，α 相會逐漸減少而 β 相則有增多趨勢。AZ80 鎂合金藉由拉伸試驗可以得知當回火溫度較高且回火時間較長的條件下，抗拉強度有增加之趨勢，在微硬度測試時熱影響區硬度值約略高於銲道，且其拉伸破斷面皆屬於脆性破壞型式。[[abstract]]This study aimed to investigate the characteristics of AZ80 magnesium alloy by TIG welding for corresponding in the same voltage and current. Tempering heat treatment process by observation of AZ80 magnesium alloy and the mechanical properties change. The experimental results shown in by X-ray diffraction analysis showed that the welded magnesium alloy AZ80 after heat treatment have β-phase (Mg17Al12) precipitation, making AZ80 magnesium alloy in ?Mg matrix phase of the composition, microstructure in the fusion zone. The Microstructure observed after the heat treatment of ?and β phase fraction compared with the tempering temperature and time will change, with the tempering temperature and tempering time meet the increase in ?decreased, the relative increase in β-phase will be . The AZ80 magnesium alloy by tensile test could be that the higher the tempering temperature and tempering under the conditions of a long time, and has the maximum tensile strength/.Hardness the will be slightly decreased when the tempering temperature and time is increased and the magnesium alloy AZ80 after tensile fracture surface is brittle failure types are