Mechanical Properties And Joining Mechanism of Magnetic Pulse Welded Aluminum To Titanium

Magnetic pulse welding of dissimilar aluminum and titanium was investigated to optimize process parameters in terms of discharge voltage, radial gap and overlapping length. Moreover, impacting modes at different overlapping lengths were discussed. The joining mechanism was analyzed from aspects of microstructure, composition and hardness distribution. The shear strength increased with increasing discharge voltages, whereas shear strength decreased at first and then increased with the increasing radial gap, which has a more significant influence on shear strength than discharge voltage. Three impacting modes were proposed as bidirectional impacting, overall impacting and single-orientation impacting. However, the single-orientation impacting mode has the highest effective joining ratio. The welded joints were divided into four transition layer interfaces: continuous transition zone, transition zone with cracks, intermittent transition zone, and non-transition zone. Waves and intermetallic compounds are the two characteristics of the Al-Ti joint welded by magnetic pulse welding. The metal's hardness near the joint surface is higher than that of the base metal. In addition, Al3Ti and aluminum base metal were found in the transition layer of the joint.

Experimental and Numerical Investigations into Magnetic Pulse Welding of Aluminum Alloy 6016 to Hardened Steel 22MnB5

By means of magnetic pulse welding (MPW), high-quality joints can be produced without some of the disadvantages of conventional welding, such as thermal softening, distortion, and other undesired temperature-induced effects. However, the range of materials that have successfully been joined by MPW is mainly limited to comparatively soft materials such as copper or aluminum. This paper presents an extensive experimental study leading to a process window for the successful MPW of aluminum alloy 6016 (AA6016) to hardened 22MnB5 steel sheets. This window is defined by the impact velocity and impact angle of the AA6016 flyer. These parameters, which are significantly dependent on the initial gap between flyer and target, the charging energy of the pulse power generator, and the lateral position of the flyer in relation to the inductor, were determined by a macroscopic coupled multiphysics simulation in LS-DYNA. The welded samples were mechanically characterized by lap shear tests. Furthermore, the bonding zone was analyzed by optical and scanning electron microscopy including energy-dispersive X-ray spectroscopy as well as nanoindentation. It was found that the samples exhibited a wavy interface and a transition zone consisting of Al-rich intermetallic phases. Samples with comparatively thin and therefore crack-free transition zones showed a 45% higher shear tensile strength resulting in failure in the aluminum base material.