铜铝搅拌摩擦焊对接接头组织性能及塑性材料流动特征研究

发布时间：2018-03-14 02:36

本文选题：铜铝接头　切入点：搅拌摩擦焊　出处：《江苏科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：在电力、电气、电子等领域,铜和铝金属都是得到广泛应用的导体材料,然而,由于铜铝接头具有连接强度高、耐腐蚀、美观等优点,铜和铝之间通常采用铜铝接头进行过渡连接。搅拌摩擦焊作为固相焊接方法,能够实现异种金属连接,对于铜铝接头的制备具有很大的应用前景。本文选用4mm板厚的T2纯铜和1060纯铝作为研究对象进行搅拌摩擦焊对接焊,探索铜铝接头组织结构特征和物相成分,研究焊接参数与搅拌头轴肩直径大小对焊缝表面成形、力学性能、电化学腐蚀性能的影响规律,同时,通过接头形貌观察实验和数值模拟方法深入探索铜铝接头金属的流动行为。合理搭配搅拌头旋转速度和焊接速度,可以获得焊缝表面成形质量较好的铜铝接头。铜铝接头区域内,轴肩影响区和焊核区内组织晶粒细小而均匀;铜侧和铝侧的热机影响区内组织晶粒也较小;铝侧热影响区的范围窄,晶粒较大,铜侧热影响区内晶粒没有明显的长大现象。铜铝接头中存在金属间化合物相CuAl_2和Cu9Al_4,相成分的类型不随焊接参数发生变化。焊接热输入较小时获得的铜铝接头在拉伸试验中表现为脆性断裂,增加搅拌头旋转速度或者减小焊接速度,接头抗拉强度升高。焊接热输入较大时获得的铜铝接头在拉伸试验中的断裂方式转变为塑性断裂,继续增加焊接热输入,接头抗拉强度小幅度下降。搅拌头轴肩直径20mm、旋转速度800rpm、焊接速度50mm/min的焊接参数为本研究的最佳参数,最佳参数下的铜铝接头抗拉强度达116.4MPa,为铝母材抗拉强度的82.6%,而且焊缝表面成形较为平整。增加搅拌头旋转速度或减小焊接速度,铜铝接头的自腐蚀电位呈下降趋势。但是,铜铝接头的腐蚀电流与焊接参数没有直接联系。轴肩作用区内金属流动强度最高,大量铜金属越过对接线进入铝侧;焊核区内,铜金属受铝金属挤压往接头底部迁移,区域内只存在少量铜金属;搅拌针底面作用区内,铜金属也能越过对接线进入铝侧,但金属流动强度较低,而且金属流动行为极不稳定。同时建立了三维流体模型,进行FLUENT模拟,模拟结果显示,轴肩作用区内金属流动强度高,金属混合区为规则的均匀过渡区,范围较大;焊核区内,铝金属在搅拌针前方被分流,部分铝金属进入前进侧,挤压铜金属往接头底部迁移;搅拌针底面作用区内,金属流动强度较低,铜铝混合区范围较小。数值模拟结果与实验结果总结的流体流动规律基本吻合。
[Abstract]:In electric power, electrical, electronics and other fields, copper and aluminum metal conductor materials are widely used, however, because the copper aluminum joint has the advantages of high connection strength, corrosion resistance, appearance and other advantages, is usually used for copper aluminum joint transition between copper and aluminum. The friction stir welding welding method for solid phase, can realize the dissimilar metal connection, preparation has great application prospect for the system. The copper aluminum joint of T2 copper 4mm thickness and 1060 pure aluminum as the research object for friction stir welding butt welding, explore organizational structure characteristics and physical phase composition of copper aluminum joint, welding parameters and tool shoulder diameter on the surface of weld forming, mechanical properties at the same time, effect of electrochemical corrosion, in-depth exploration of flow behavior of copper aluminum joint metal through the joint morphology experiment and numerical simulation method. The reasonable collocation of tool rotation speed And the welding speed can be obtained, the weld forming aluminum joints with high quality. Copper aluminum joint region, shoulder affected zone and weld nugget zone microstructure with fine grains and uniform grain area; heat effect of copper and aluminum side side is smaller; the aluminum side heat affected zone is narrow, large grains, copper side the heat affected zone has no obvious grain growth phenomenon. The existence of intermetallic compound CuAl_2 and Cu9Al_4 aluminum joints, the type of phase composition with the change of welding parameters. The welding heat input is small aluminum joints obtained in tensile tests showed brittle fracture, increasing rotating speed or decreasing welding speed increased the tensile strength of welding heat input. Change the fracture mode in a tensile test of copper aluminum joint is larger the plastic fracture, continue to increase the tensile strength of the welding heat input, small decline. Stir Head shoulder diameter 20mm, rotating speed 800rpm, welding speed 50mm/min welding parameters for the best parameters of this study, copper aluminum joint tensile strength under the optimum parameters for aluminum was 116.4MPa, the tensile strength of the base metal and weld surface forming 82.6%, relatively flat. Increasing the stirring head speed or decreasing welding speed, since the copper aluminum joint the corrosion potential decreased. However, the corrosion current of aluminum joints have no direct connection with the welding parameters. The shoulder area of metal flow intensity is highest, a large number of copper wiring crossed on into the aluminum side; weld nugget zone, to the joint at the bottom of aluminum extrusion of copper metal by metal migration, only the presence of a small amount of copper in the region; the bottom surface of the pin function area, can be crossed on copper wiring into the aluminum side, but the metal flow intensity is low, and the metal flow behavior is extremely unstable. At the same time to establish the three-dimensional flow model, FL UENT simulation, simulation results show that the shoulder area of metal flow, high strength, uniform mixing zone metal transition zone, the scope of the rule is greater; the weld nugget zone, aluminum metal is split pin in the front part of the aluminum metal into the advancing side, extrusion of copper metal into the joint at the bottom of the bottom surface of the pin function of migration; within the area of metal flow in low intensity region is smaller than the mixed copper. Numerical simulation results and experiment results of fluid flow regularities are basically consistent.

【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG453.9

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