Ramaswamy Addanki, Nagasai Bellamkonda Prasanna, Dwivedy Maheshwar, Malarvizhi Sudersanan, Balasubramanian Visvalingam
Department of Mechanical Engineering, SASI Institute of Technology & Engineering, Tadepalligudem, India.
Department of Mechanical Engineering, SRM University-AP, Mangalagiri, Andhra Pradesh, India.
Microsc Res Tech. 2024 Jun;87(6):1210-1221. doi: 10.1002/jemt.24510. Epub 2024 Feb 2.
Aluminium (Al) and magnesium (Mg) alloys are extensively used in the automobile sector because of their high strength-to-weight ratio, excellent castability low density and simplicity of recycling. Al-Mg structures used in the automotive sector can potentially reduce their weight. Although there is a significant opportunity for substantial cost reduction, the use of magnesium in aluminium structures remains restricted. This study aims to weld 3 mm-thick rolled sheets of AA6061 Al and AZ31B Mg alloy using the cold metal transfer (CMT) arc welding process. Three different filler wires (ER1100, ER4043, and ER5356) were used in the experiment. In this article, the mechanical and microstructure characteristics of Al/Mg dissimilar joints manufactured by CMT are evaluated and discussed in detail. Optical microscope (OM), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to analyze the CMT-welded Al/Mg dissimilar joints. Of the three filler wires used, ER4043 (Al-5%Si) filler wire yielded defect-free sound joints due to the presence of Si, which improves the flow ability of molten filler during welding. The presence of Mg-rich intermetallics-AlMg and Al-rich intermetallics-AlMg were observed. The fractured area of the CMT-welded Al/Mg dissimilar joints revealed the presence of the Mg-rich intermetallics (AlMg), which is responsible for the decrease in tensile strength. The reduction of intermetallics, particularly of Mg-rich intermetallics (AlMg) is important for improving joint strength. RESEARCH HIGHLIGHTS: Cold metal transfer (CMT) arc welding was used to control the Al-Mg-rich intermetallics in the Al/Mg dissimilar joints. The microstructure, morphology and phase composition of the welded joints were studied by OM, SEM, TEM, EDS and XRD. The weld metal and AL substrate bonded with a strong interface, while weld metal and Mg substrate were joined at the epitaxial solidification area where the intermetallic compounds of MgAl, MgAl and MgSi are generated. The weld metal on the Mg side experienced brittle fracture, with a continuous distribution of MgAl, MgAl and MgSi.
铝（Al）和镁（Mg）合金因其高强度重量比、优异的铸造性、低密度和回收简便性而在汽车领域得到广泛应用。汽车领域使用的铝镁结构有可能减轻其重量。尽管存在大幅降低成本的重大机会，但镁在铝结构中的使用仍然受到限制。本研究旨在使用冷金属过渡（CMT）弧焊工艺焊接3毫米厚的AA6061铝和AZ31B镁合金轧制板材。实验中使用了三种不同的填充焊丝（ER1100、ER4043和ER5356）。在本文中，对通过CMT制造的铝/镁异种接头的力学和微观结构特征进行了详细评估和讨论。使用光学显微镜（OM）、扫描电子显微镜（SEM）、能量色散X射线光谱仪（EDX）和X射线衍射仪（XRD）对CMT焊接的铝/镁异种接头进行分析。在所使用的三种填充焊丝中，ER4043（Al-5%Si）填充焊丝由于硅的存在而产生了无缺陷的优质接头，硅可提高焊接过程中熔融填充金属的流动能力。观察到富镁金属间化合物AlMg和富铝金属间化合物AlMg的存在。CMT焊接的铝/镁异种接头的断裂区域显示存在富镁金属间化合物（AlMg），这是导致抗拉强度降低的原因。减少金属间化合物，特别是富镁金属间化合物（AlMg）对于提高接头强度很重要。研究亮点：使用冷金属过渡（CMT）弧焊来控制铝/镁异种接头中富铝镁金属间化合物。通过OM、SEM、TEM、EDS和XRD研究了焊接接头的微观结构、形态和相组成。焊缝金属与铝基板通过强界面结合，而焊缝金属与镁基板在外延凝固区域结合，在该区域生成了MgAl、MgAl和MgSi金属间化合物。镁侧的焊缝金属发生脆性断裂，MgAl、MgAl和MgSi连续分布。
