本文選題：攪拌摩擦焊 + 6016鋁合金�。� 參考：《重慶交通大學(xué)》2017年碩士論文

【摘要】：攪拌摩擦焊作為一種新型固相連接技術(shù),因為焊接溫度比較低,可以焊接傳統(tǒng)焊接方法性能較差的多種輕合金材料。目前國內(nèi)外關(guān)于攪拌摩擦焊的研究主要集中在2000系和7000系鋁合金,對6000系鋁合金研究較少,尤其汽車中常用的6016鋁合金的研究更少。隨著汽車輕量化概念日趨人心,尋找車用薄板攪拌摩擦焊接工藝參數(shù),掌握其技術(shù)關(guān)鍵顯得尤為重要。本文以1 mm厚6016-T4P車用薄板鋁合金為研究對象,進行了無針攪拌摩擦焊的對接與搭接實驗研究。采用萬能拉伸試驗機、光學(xué)顯微鏡、顯微硬度測試機、掃描電鏡(帶EBSD)等多種現(xiàn)在分析手段,對不同工藝參數(shù)下接頭的宏觀和微觀組織、拉伸剪切性能、維氏硬度、內(nèi)部缺陷、接頭斷裂模式及斷裂機理進行了研究分析。實驗結(jié)果表明:當(dāng)工藝參數(shù)選擇合適時,焊縫表面成型較好,如果工藝參數(shù)選擇不當(dāng),則會出現(xiàn)起皮、背部間隙等缺陷。在對焊實驗中,焊縫性能與焊縫宏觀成型趨勢基本一致;當(dāng)攪拌頭轉(zhuǎn)速為1200 r/min,焊接速度為400 mm/min時,焊縫強度達(dá)到最高,為218 MPa達(dá)到母材的90.8%。在搭焊實驗中,由于搭焊的特殊性,焊縫性能與焊縫宏觀成型趨勢相差較大;當(dāng)攪拌頭轉(zhuǎn)速為1600 r/min,焊接速度為200 mm/min時,焊縫強度達(dá)到最高,為223 MPa達(dá)到母材的92.9%。焊接區(qū)硬度均低于母材區(qū),焊核區(qū)硬度高于熱機影響區(qū)與熱影響區(qū),硬度最低點出現(xiàn)在熱影響區(qū)附近;搭焊中焊核區(qū)上板硬度大于下板,熱影響區(qū)下板硬度大于上板。當(dāng)熱輸入量不足時,在接頭組織中發(fā)現(xiàn)孔洞、背部間隙、界面遷移等缺陷。焊縫力學(xué)性能較好的試樣斷裂形式為韌性斷裂;焊縫力學(xué)性能較差的試樣斷裂形式為韌性和脆性相混合的混合型斷裂。焊核區(qū)晶粒被明顯細(xì)化,組織分布均勻;熱機影響區(qū)晶粒被拉長發(fā)生了彎曲變形;熱影響區(qū)晶粒相對于母材發(fā)生了略微粗化。
[Abstract]:Friction stir welding (FSW) is a new type of solid-phase bonding technology. Because of the low welding temperature, friction stir welding (FSW) can be used to weld many kinds of light alloy materials with poor performance of traditional welding methods. At present, the research on friction stir welding is mainly focused on 2000 series and 7000 series aluminum alloy, and less on 6000 series aluminum alloy, especially 6016 aluminum alloy, which is commonly used in automobile. With the increasing popularity of the concept of lightweight automobile, it is very important to find out the technical parameters of friction stir welding of automobile thin plate and master the key technology. In this paper, 1 mm thick 6016-T4P thin plate aluminum alloy is used as the research object, and the butt joint and lap joint of needle-less friction stir welding are studied. By using universal tensile testing machine, optical microscope, microhardness tester, scanning electron microscope (EBSD) and so on, the microstructure, tensile and shear properties, Vickers hardness and internal defects of joints under different technological parameters were studied. The fracture mode and fracture mechanism of the joint were studied and analyzed. The experimental results show that the weld surface is well formed when the process parameters are selected properly, and if the process parameters are not chosen properly, the defects such as peeling and back clearance will appear. In the butt welding experiment, the weld performance is basically consistent with the macroscopic forming trend of the weld, when the speed of the stirring head is 1200 r / min and the welding speed is 400 mm/min, the weld strength reaches the highest and the base metal reaches 90.8% for 218 MPa. In the lap welding experiment, because of the particularity of the lap welding, the weld performance is different from the macroscopic forming trend of the weld, when the speed of the stirring head is 1600 r / min and the welding speed is 200 mm/min, the weld strength is the highest, and that of the base metal is 92.9% for the 223 MPa. The hardness of the welding zone is lower than that of the base metal area, and the hardness of the nuke zone is higher than that of the heat affected zone and the heat affected zone, and the lowest hardness occurs near the heat affected zone, and the hardness of the upper plate is greater than that of the lower plate, and the hardness of the heat affected zone is greater than that of the upper plate. When the heat input is insufficient, defects such as hole, back clearance, interface migration and so on are found in the joint structure. The fracture form of the specimen with better mechanical properties of weld is ductile fracture, and the fracture form of the specimen with poor mechanical properties of weld is mixed mode fracture of toughness and brittleness. The grains in the nugget zone were refined and distributed uniformly, the grains in the heat-affected zone were elongated and distorted, and the grains in the heat-affected zone were slightly coarser than those of the base metal.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG453.9

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