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Two types of intermediate layer (IML) were formed at the magnetic pulse welded Al/Fe joint interface. To clarify the formation mechanism of IML, the cooling process at the joint interface and formation process of IML were analyzed by the simulation and experiment. The simulation results showed that the crest zone of wavy interface underwent an extremely high temperature rise during the collision process, the high temperature leads to a local melting behavior at the joint interface. After the collision, a large temperature difference of 1000-1500K between joint interface and base metals caused a rapid cooling occurred at the interface with a cooling rate reached around 107~109K/s. Meanwhile, local melting zone (LMZ) changed into IML during a rapid solidification that proceeded from the outside and finished at the center area of LMZ. The morphology and composition percent of IML calculated by the numerical analysis was quantitatively in good agreement with experimental analysis results. A reasonable explanation has been made on the formation mechanism of IML at magnetic pulse welded Al/Fe joint interface. [ABSTRACT FROM AUTHOR]

A 1050-O aluminum plate and a low carbon steel (SPCC) plate were seam welded by magnetic pulse welding (MPW). Experimental and numerical analysis methods were combined to investigate the wavy interface formation and local melting phenomena at the Al/Fe joint interface. The metallographic observation results showed that Al/Fe joint interface presents a trigger-like wave shape with two types of intermediate layers intermittently formed at the interface. Collision angle between two plates and impact velocity of Al sheet driven by electromagnetic force was numerically solved by coupled mechanical and electromagnetic fields analysis. The metal jet emission behavior, wavy interface formation process and the temperature change during MPW collision process was analyzed by SPH method. The numerical results showed that the temperature near the interface exceeds the melting point of both Al and Fe at extremely high pressure, which leads to the formation of a local melting zone (LMZ) where Al and Fe were mixed in melted state. The numerically reproduced wavy interface morphology showed a good consistency with the experimentally observed results. [ABSTRACT FROM AUTHOR]

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Collision welding is a high-speed joining technology based on the plastic deformation of at least one of the joining partners. During the process, several phenomena like the formation of a so-called jet and a cloud of particles occur and enable bond formation. However, the interaction of these phenomena and how they are influenced by the amount of kinetic energy is still unclear. In this paper, the results of three series of experiments with two different setups to determine the influence of the process parameters on the fundamental phenomena and relevant mechanisms of bond formation are presented. The welding processes are monitored by different methods, like high-speed imaging, photonic Doppler velocimetry and light emission measurements. The weld interfaces are analyzed by ultrasonic investigations, metallographic analyses by optical and scanning electron microscopy, and characterized by tensile shear tests. The results provide detailed information on the influence of the different process parameters on the classical welding window and allow a prediction of the different bond mechanisms. They show that during a single magnetic pulse welding process aluminum both fusion-like and solid-state welding can occur. Furthermore, the findings allow predicting the formation of the weld interface with respect to location and shape as well as its mechanical strength. [ABSTRACT FROM AUTHOR]