使用自我支持式攪拌棒於摩擦攪拌銲接之接合特性研究

Abstract

本論文以鋁合金為研究對象，分兩部分進行研究：第一部分為使用自行設計的自我支持式攪拌棒(Self-reacting pin tool)或稱線筒軸形攪拌棒(Bobbin tool)對不同鋁合金材質進行摩擦攪拌銲接(Friction stir welding)，在不使用外加熱源的情況下進行摩擦攪拌銲接，探討自我支持式攪拌棒對不同鋁合金的銲接可行性。第二部分承第一部分所實驗出來的結果，決定試片的材質，探討在固定銲接速度下，改變轉速，對其銲後的機械性質影響，再經由光學顯微鏡及掃描式電子顯微鏡觀察其顯微組織。 本研究中利用自我支持式攪拌棒對鋁合金1050進行銲接，可成功接合鋁合金1050，隨著轉速的提高在金相顯微組織上類似沙漏狀結構的銲核區(Weld nugget zone, WNZ)會越來越明顯，而在銲核區的缺陷會隨著轉速的提高有明顯增加。隨著轉速的提高，在軟化區的硬度也跟著下降，其硬度均低於母材，但在銲核區硬度值會隨轉速提高而增加。在拉伸試驗中抗拉強度會隨著轉速提高而增加，而平均抗拉強度可達母材的59%。利用掃描式電子顯微鏡觀察拉伸試驗破斷後的破斷面，均為延性破壞。

This study was divided into two parts. First, we used self-reacting pin tool (or could be known as a bobbin tool)which was designed by myself to weld different aluminum alloy by friction stir welding without any heat source, and discussed the possibility of welding. Second, according to experiments of first part, we decided the material of specimen and discussed the mechanical properties under various rotating speed at fixed welding speed. Last, the specimen was observed by metallographic test, optical microscope and scanning electron microscope. A 1050 aluminum alloy was friction stir welded by self-reacting pin tool. The geometry of the weld nugget zone (WNZ) obviously displayed saddle sharp with the increasing rotation speed. The defects in WNZ were significantly raising with the increasing welding speed. The values of microhardness at soft region were lower than base material and it decreased with the increasing welding speed, but the microhardness in WNZ was increased with increasing welding speed. Ultimate tensile strengths would be increased with increasing welding speed in the tensile tests. And the average ultimate tensile strength of specimen could reach 59% of the base material. The tensile fracture surfaces of the joints were analyzed by scaning electron microscope, as presented the ductile fracture mode.