摘要6061铝合金为铝镁硅合金，它加工性能极佳，具有良好的腐蚀性，由于韧性高，所以加工不易变形，易于抛光上色。目前应用广泛，航空航天，交通运输，电子，家电，包装等领域都会用到6系铝合金。86173

    对6061-T6及6061-O铝合金采用搅拌摩擦焊方法分别进行对接焊，板厚5mm，焊后采用光学显微镜、扫描电镜进行分析，对比O-O接头、O-T6接头、T6-T6接头及母材的显微组织和断口形貌，并测试了拉伸性能和显微硬度。

用万能材料试验机测试母材及接头的拉伸性能，O-O接头、O-T6接头、T6-T6接头断裂方式都是韧性断裂，断口都有明显韧窝。T6-T6接头的抗拉强度最高，约为184MPa，O-O接头的延伸性最好，可达到24%；

    用显微硬度仪测试母材及接头的硬度，O-T6接头的硬度在前景侧呈现上升的趋势，在后退侧，从母材到热影响区硬度一直下降，热机影响区到焊核区硬度上升，在焊核区部分，靠近T6母材的一侧硬度高于靠近O态的一侧；T6-T6接头硬度呈“W”形，沿焊缝厚度方向上，上部分焊缝的硬度高于中部和下部；O-O接头焊核区和热机影响区的硬度要远大于母材；

轴肩影响区、焊核区、热机影响区、热影响区和母材间因为组织的差异存在着明显的分界：轴肩影响区组织最为细小，焊核区组织比较细小，由细小的等轴晶组成；热机影响区组织比焊核区稍微粗大一些；热影响区的组织粗大。

毕业论文关键词：搅拌摩擦焊；6061铝合金；焊缝性能；组织

Abstract 6061 aluminum alloy，which mixed with magnesium and silicon，has a excellent machining performance and good corrosion resistance。Because of high toughness,6061 aluminum alloy is uneasy to be out of shape and easy to be polished。Nowadays,it’s widely used in aerospace,transportation,electronics,electrical appliances,packing and so on。

The 6061-T6 and 6061-O aluminium alloy was welded by stirring friction welding whose thickness is 5mm。 Then,we use optical microscope, scanning electron microscope analysis,making comparison of O-O joint, O-T6 joint, T6-T6 joint and base material。Microstructure and fracture morphology are made to test the tensile and microhardness。

Tensile properties was tasted by universal material testing machine。O-O joint, O-T6 joint, T6-T6 joint fracture mode is tough fracture。The fracture surface has obvious tough pit。The tensile strength of T6-T6 joint is the highest, which is about 184MPa, and the extension of O-O joint is the best, which can reach 24%;

The hardness of base metal and joint was tested by micro-hardness meter。The hardness of O-T6 joint showed an upward trend。On the back side, the hardness of the base material to HAZ has been decreased。The hardness of TMAZ to NZ has been increased。 In weld nugget zone, the hardness of half part,which is closer to 6061-O aluminum alloy,is higher than another;T6-T6 joint’s micro-hardness was a "W" shape。Along the direction of the weld thickness, weld hardness is higher than the middle and lower。 The hardness of the O-O joint in NZ and HAZ is far higher than the based material;

There’s a obvious boundary existed between NZ,HAZ,TMAZ and BM, and theirs microstructure are different from each other: organization of the NZ is relatively small, which consisting of fine equiaxed grains; TMZA is a litter bigger than NZ; HAZ has the biggest microstructure。

Keywords：Friction stir welding；6061 aluminum alloy；Performance of weld；Organization。

目   录

第1章 绪 论 1

1。1 引 言 1

1。2 搅拌摩擦焊概况 2

1。21 搅拌摩擦焊的原理