本研究以AA6061-T6鋁合金為實驗材料。選擇對接接頭，進行鎢極氣體保護電弧銲(GTAW銲)及金屬極氣體保護電弧銲(GMAW銲)並在銲件設置背吹板，觀察不同銲接工藝及背吹板對鋁合金銲件在拉伸測試以及疲勞測試下的機械性質與疲勞壽命的影響。 研究顯示銲接時在銲件底部設置背吹板可縮小銲道根部面積，但有無背吹板對銲件的抗拉強度並無明顯的關聯，主要的原因為銲件拉伸斷裂位置皆在熱影響區上的軟化區與銲道截面形狀的變化無關，軟化區受到銲接熱影響造成微結構改變機械強度下降，銲件疲勞試片的斷裂點主要發生在銲道根部靠近熱影響區的位置， 三種板厚中以2mm的銲件疲勞壽命最高原因為較薄的試片中疲勞裂紋閉合程度較高疲勞裂紋延伸較慢所導致，在本實驗設定之疲勞限N=106回下板厚2mm 銲件疲勞強度相比板厚3mm 及板厚4mm 提高約8~12%，而板厚4mm的銲件在背吹板上進行銲接容易捲入氣體，使銲道上出現氣孔造成銲接品質不佳機械性質與疲勞壽命下降，將銲接過程背吹板氣體使用氬氣代替壓縮空氣，可減少氣體捲入銲道產生氣孔，提高銲接品質與穩定性。 ;This study used AA6061-T6 aluminum alloy as the experimental material. Butt joints were selected for tungsten inert gas welding (GTAW) and gas metal arc welding (GMAW) processes, with the addition of a back purge plate during welding. The objective was to investigate the impact of different welding processes and the use of a back purge plate on the mechanical properties and fatigue life of aluminum alloy weldments under tensile testing and fatigue testing. The findings indicated that for both GTAW and GMAW weldments, the fracture locations of fatigue test specimens were primarily in the weld root area near the heat-affected zone. The use of 2mm thick plates resulted in an approximately 8-12% increase in fatigue life compared to plates with 3mm and 4mm thicknesses. In the case of 4mm thick plate weldments, welding on the backside of the plate was prone to gas entrapment, leading to the formation of porosity in the weld bead, which adversely affected the mechanical properties and fatigue life. However, by replacing compressed air with argon gas during the backside welding process, the occurrence of gas entrapment and porosity in the weld bead was reduced, thereby enhancing welding quality and stability.
Keywords：AA6061、Aluminium、Gas Tungsten Arc Welding、Gas Metal Arc Welding、Fatigue Life
