6016铝合金无针搅拌摩擦焊工艺及接头性能研究

发布时间：2018-04-20 23:09

本文选题：搅拌摩擦焊 + 6016铝合金　；参考：《重庆交通大学》2017年硕士论文

【摘要】：搅拌摩擦焊作为一种新型固相连接技术,因为焊接温度比较低,可以焊接传统焊接方法性能较差的多种轻合金材料。目前国内外关于搅拌摩擦焊的研究主要集中在2000系和7000系铝合金,对6000系铝合金研究较少,尤其汽车中常用的6016铝合金的研究更少。随着汽车轻量化概念日趋人心,寻找车用薄板搅拌摩擦焊接工艺参数,掌握其技术关键显得尤为重要。本文以1 mm厚6016-T4P车用薄板铝合金为研究对象,进行了无针搅拌摩擦焊的对接与搭接实验研究。采用万能拉伸试验机、光学显微镜、显微硬度测试机、扫描电镜(带EBSD)等多种现在分析手段,对不同工艺参数下接头的宏观和微观组织、拉伸剪切性能、维氏硬度、内部缺陷、接头断裂模式及断裂机理进行了研究分析。实验结果表明:当工艺参数选择合适时,焊缝表面成型较好,如果工艺参数选择不当,则会出现起皮、背部间隙等缺陷。在对焊实验中,焊缝性能与焊缝宏观成型趋势基本一致;当搅拌头转速为1200 r/min,焊接速度为400 mm/min时,焊缝强度达到最高,为218 MPa达到母材的90.8%。在搭焊实验中,由于搭焊的特殊性,焊缝性能与焊缝宏观成型趋势相差较大;当搅拌头转速为1600 r/min,焊接速度为200 mm/min时,焊缝强度达到最高,为223 MPa达到母材的92.9%。焊接区硬度均低于母材区,焊核区硬度高于热机影响区与热影响区,硬度最低点出现在热影响区附近;搭焊中焊核区上板硬度大于下板,热影响区下板硬度大于上板。当热输入量不足时,在接头组织中发现孔洞、背部间隙、界面迁移等缺陷。焊缝力学性能较好的试样断裂形式为韧性断裂;焊缝力学性能较差的试样断裂形式为韧性和脆性相混合的混合型断裂。焊核区晶粒被明显细化,组织分布均匀;热机影响区晶粒被拉长发生了弯曲变形;热影响区晶粒相对于母材发生了略微粗化。
[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.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG453.9

【参考文献】