純鈦與6061鋁合金摩擦攪拌異質接合之機械性質與抗腐蝕特性研究

Abstract

本研究使用摩擦攪拌銲接的技術搭配對接及搭接兩種方式用於純鈦與6061鋁合金之異質接合，摩擦攪拌銲接利用高速鋼作為攪拌棒，攪拌棒之傾斜角設定為2∘，探討在不同主軸轉速及進給速度下對於銲道性質之影響，將各成功接合之試片進行顯微組織及機械性質測試，並進行元素分布分析，最後進行殘留應力量測及抗腐蝕能力分析。 實驗結果顯示對接時主軸轉速設定1000 rpm、進給速度100 mm/min可以得到較好的銲道性質；搭接時則是主軸轉速設定1200 rpm、進給速度120 mm/min可以得到較好的銲道性質，兩種接合方法比較時，對接比起搭接可以獲得更好的抗拉強度。除此之外，兩種銲接方式都在攪拌區可以觀察到晶粒細化的效果，但是熱影響區晶粒較大，使熱影響區有硬度下降的趨勢，造成對接試片會在熱影響區發生斷裂；在搭接時兩種材料界面會形成硬脆的介金屬化合物，其硬度將近300HV高於純鈦母材，由於硬度高、延性差因此搭接試片斷裂時會發生在接合界面處。進行殘留應力量測發現摩擦攪拌銲接試片與典型的對接殘留應力相反，在銲道處顯示為壓應力。銲接件抗腐蝕能力的部分，銲道的攪拌區由於晶粒細化的緣故，其抗腐蝕性能優於其他區域。

In this study, the technology of friction stir welding was used to join the dissimilar materials of aluminum alloy 6061 and commercially pure titanium by means of butt joint and lap joint. High-speed steal stir rod was used for the friction stir welding, and a 2o title was applied to the stir rod during friction stir welding. To discuss the influence of different rotating speeds and travel speed, the specimens were analyzed for their microstructure, mechanical properties, and elemental analysis was carried out, finally the residual stress measurement and corrosion resistance analysis were performed followed by the friction stir welding. Experimental results showed that the best weld bead properties of the butt joint can be obtained by setting the rotational speed of 1000 rpm and the travel speed of 100 mm/min; and the best weld bead of the lap joint can be obtained by setting the rotational speed to 1200 rpm and the travel speed of 120 mm/min. When comparing the two joining methods, the butt joint has better tensile strength than the lap joint. In addition, the two welding methods can observe the effect of grain refinement in the stirring zone, but the grain in the heat-affected zone is larger, and the heat-affected zone has a tendency to decrease in hardness, causing failure in the heat-affected zone when using butt joint. As for the lap joint, the interface between the two materials will form intermetallic compounds, the hardness of which is nearly 300HV, higher than that of the pure titanium base material, and fractured at the interface, which was attributed to the presence of intermetallic compounds. The residual stress portion is opposite to the typical butt residual stress, showing compressive stress at the weld bead, which is good for the weld bead. In addition, the stir zone is superior to other regions in the corrosion resist test due to grain refinement.