铝/镁异种合金磁脉冲焊接接头组织与性能研究

Study on Microstructure and Mechanical Properties of Al/Mg Dissimilar Metal Sheet Joints by Magnetic Pulse Welding

本工作采用磁脉冲焊接方法实现了铝/镁异种合金的连接,并通过光学显微镜、扫描电镜、X射线衍射和拉伸试验等分析方法对不同放电能量下的接头微观组织及力学性能进行研究。结果表明,铝/镁异种合金焊接接头界面呈现波形界面和平直界面,且随着放电能量的增加,界面的有效结合区宽度逐渐增加,最大达到了2.87 mm;波形界面的特征越明显,接头的力学性能越高;当放电能量为30 kJ时,波形界面的波长为62.7μm,波幅为9.1μm,接头拉剪力最大,达4 679.5 N。断口形貌分析结果表明,焊缝由内、外两个椭圆环组成;内环形貌呈密集的颗粒与空洞混合结构,外环形貌为条纹状结构。机械互锁和冶金结合同时存在的波状结构界面是获得力学性能优异的铝/镁异种合金磁脉冲焊接接头的关键。

In this work, the magnetic pulse welding was used to realize the joining between aluminum/magnesium dissimilar alloys sheets. The microstructure and mechanical properties of the joints obtained under different discharge energies were explored by optical microscope, scanning electron microscope, X-ray diffraction(XRD) and tensile test analysis methods. The results showed that the joint interface presents a waveform structure and straight structure. With the increase of discharge energy, the effective binding zone width of the interface increases gradually, reaching a maximum of 2.87 mm and the undulations at the waveform interface and the mechanical properties of the joints increased accordingly. The highest tensile shear load of the joints reached 4 679.5 N occur in discharge energy of 30 kJ, whose wave had wavelengths of 62.7 μm and amplitudes of 9.1 μm. The fracture morphology of the joints was analyzed and the results show that the weld joint was divided into two ellipse rings. Particles and a few voids were found in the inner ring, and the outer ring had streak structure. The high tensile shear load of the Al/Mg dissimilar joints was attributed to the formation of waveform structure interface which possess both mechanical interlocking and metallurgical bonding.