Cold Metal Transfer joining of magnesium AZ31B-to-aluminum A6061-T6
Cold Metal Transfer joining of magnesium AZ31B-to-aluminum A6061-T6
复制标题
镁 AZ31B 与铝 A6061-T6 的冷金属转移连接
DOI：
10.1016/j.msea.2012.09.065
复制
发表时间：
2013-01-10
期刊：
影响因子：
6.4
通讯作者：
Wang, Pei-Chung
中科院分区：
文献类型：
--
作者：
Cao, R.;Wen, B. F.;Wang, Pei-Chung
汽车制造商面临着越来越大的压力，要求他们减轻车辆重量，提高燃油经济性，减少排放，提高车辆的安全性和性能。因此，越来越多的车辆结构是使用钢、铝和镁等不同材料的组合建造的。尽管这种混合制造方法具有巨大的潜在优势，但它给车辆结构的设计和相关的连接工艺带来了巨大的技术挑战。一旦两种元素(如镁-铝、铝-钢)在高温熔池中混合，就很容易形成脆性金属间化合物相(IMP)。实验观察表明，一系列金属间化合物相将大大降低焊接异种材料的力学性能。本研究采用直径1.6 mm的铝填充焊丝4047对1 mm厚的镁AZ31B和1 mm厚的铝A6061-T6进行了焊接试验。采用冷熔滴过渡(CMT)弧焊技术。这一过程的关键特点是将钢丝的运动融入了对过程的整体控制中。在短路过程中，焊丝回缩运动有助于熔滴脱离，因此金属可以在不受电磁力的帮助下转移到焊接熔池中。通过这种方式，可以控制热输入和飞溅，并最大限度地减少IMP的形成，从而提高接头强度。进行了大量的实验，并进行了分析。结果表明，虽然已采取了大量措施控制热输入，但焊缝中仍有富镁金属间化合物-Al12Mg17和富铝金属间化合物β-Al3Mg2生成。AZ31B-Al6061-T6 CMT焊接接头断口呈富镁金属间化合物(γ-Al12Mg17)，这是导致焊接强度劣化的主要原因。为了改善接头，最大限度地减少金属间化合物，特别是富镁金属间化合物(伽马-Al12Mg17)的含量是至关重要的。(C)2012爱思唯尔B.V.保留所有权利。
Automotive manufacturers are faced with increasing pressure to reduce vehicle weight, improve fuel economy, reduce emissions, and enhance vehicle safety and performance. Therefore, an increasing number of vehicle structures are built using a combination of dissimilar materials such as steel, aluminum and magnesium. Though the advantages are potentially huge, this hybrid fabrication approach raises substantial technical challenges to the design of vehicle structures and the associated joining processes. Once two elements (e.g., magnesium-aluminum, aluminum-steel) are mixed in a high temperature welding pool, brittle intermetallic phases (IMP) can be easily formed. Experimental observations showed that a series of intermetallic phases will greatly reduce the mechanical performance of the welded dissimilar materials.In this study, welding of 1 mm thick magnesium AZ31B-to-1 mm thick aluminum A6061-T6 using a 1.6 mm diameter aluminum filler wire 4047 was investigated. Cold Metal Transfer (CMT) arc welding technique was adopted. The key feature of this process is that the motion of the wire has been integrated into the overall control of the process. The wire retraction motion assists droplet detachment during the short circuit, thus the metal can transfer into the welding pool without the aid of the electromagnetic force. In this way the heat input and spatter can be controlled and the IMP formation minimized thereby improving the joint strength. Extensive experiments were performed and analyzed. It was found that although extensive efforts have been exercised to control the heat input, Mg-rich intermetallic gamma-Al12Mg17 and Al-rich intermetallic beta-Al3Mg2 were still produced in the weld. Fracture surfaces of CMT welded AZ31B-Al6061-T6 joints exhibited the Mg-rich intermetallic (gamma-Al12Mg17) which contributes to the weld strength degradation. To improve the joint, minimizing the content of the intermetallics especially Mg-rich intermetallics (gamma-Al12Mg17) is essential. (C) 2012 Elsevier B.V. All rights reserved.