Magnetic Pulse Hybrid Joining of Polymer Composites to Metals

To lighten their vehicles, car manufacturers are inclined to substitute steel structures with aluminum alloys or composites parts. They are then faced with the constraints inherent to dissimilar (galvanized steel/aluminum) or hybrid (metal/composite) assemblies. Recent developments in magnetic pulse welding seems to offer a viable route. Very fast, this process can be robotized and generates a very localized heating system which limits the formation of intermetallic and damage the composite. Low energy consumption, without filler metal or smoke it is recognized as an environmentally friendly process. In this paper, electromagnetic pulse welding is exploited to assemble polymer composite to metals. Two techniques, a metallic insert in polymer composite or an external patch, have been tested with possible design considerations.

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.

Hierarchical Morphology and Formation Mechanism of Collision Surface of Al/Steel Dissimilar Lap Joints via Electromagnetic Pulse Welding

The aim of this study was to characterize detailed microstructural changes and bonding characteristics and identify the formation mechanism of collision surface of Al6061–Q355 steel dissimilar welded joints via electromagnetic pulse welding (EMPW). The collision surface was observed to consist of five zones from the center to the outside. The central non-weld zone exhibited a concave and convex morphology. The welding-affected zone mainly included melting features and porous structures, representing a porous joining. The secondary weld zone presented an obvious mechanical joining characterized by shear plateaus with stripes. The primary weld zone characterized by dimples with cavity features suggested the formation of diffusion or metallurgical bonding. The impact-affected zone denoted an invalid interfacial bonding due to discontinuous spot impact. During EMPW, the impact energy and pressure affected the changes of normal velocity and tangential velocity, and in turn, influenced the interfacial deformation behavior and bonding characteristics, including the formation of micropores which continued to grow into homogeneous or uneven porous structures via cavitation, surface tension, and depressurization, along with the effect of trapped air.

Double-Pulse Triple-Wire MIG Welding of 6082-T6 Aluminum Alloy: Process Characteristics and Joint Performances

High-efficiency and high-quality welding has always been the focus of welding research. This article proposes a novel double-pulse, triple-wire MIG welding process for the welding of 6082-T6 aluminum alloy. The process characteristics of welding arc and droplet transfer were studied, and the performances of weld formation, morphology, hardness, and tensile strength were tested for the 1 Hz, 3 Hz, and 5 Hz double-pulse welding and normal-pulse welding. It was found that in the welding process, the pulsed arc steadily alternated among three welding wires without arc interruption, and the arc length changed periodically with the double-pulse frequency. The droplets transferred with a stable one-pulse-one-drop mode. Besides, a proper double-pulse frequency, e.g., 3 Hz in this case, was conducive to forming good welds with regular fish-scale patterns and no pores. The tensile strength of the joint could reach 64% of the base material’s tensile strength, and its fracture belonged to plastic fracture, which occurred in the HAZ. This new welding method will have great potential in aluminum alloy welding.