Influence of the jet velocity on the weld quality of magnetic pulse welded dissimilar sheet joints of aluminum and steel

Abstract

The object of this investigation is to determine the influence of the jet velocity on the weld quality of sheet joints produced via magnetic pulse welding. The use of a suitable high-speed camera system enables to observe the jet in detail, to determine its velocity during the collision process and to compare them to the achieved qualities (tensile strength, weld seam characteristics) of the welded samples. The results show that the quality of the weld generally correlates with the jet velocity, however the mere consideration of its velocity proves not to be a promising approach for predicting a specific weld quality. It becomes evident that the jet thickness has to be considered, since quality-critical characteristics of the weld seam appears in greater extent when the jet thickness increases.Keywords: Magnetic pulse welding / asymmetric impact / jetting / high-speed imaging / weld quality Gegenstand der Untersuchung ist die Ermittlung des Einflusses der Jetgeschwindigkeit auf die Schweißnahtqualität magnetimpulsgeschweißter Blechverbindungen. Die Verwendung eines geeigneten Hochgeschwindigkeitskamerasystems ermöglicht es, den Jet im Detail zu beobachten sowie seine Geschwindigkeit während der Kollision zu erfassen und diese den erzielten Qualitäten (Zugfestigkeit, Schweißnahtcharakteristiken) der verschweißten Proben gegenüberzustellen. Die Ergebnisse verdeutlichen, dass die Qualität der Schweißverbindung im Allgemeinen mit der Jetgeschwindigkeit korreliert, jedoch erweist sich die alleinige Berücksichtigung seiner Geschwindigkeit als ein nicht vielversprechender Ansatz, um eine spezifische Schweißnahtqualität prognostizieren zu können. Es wird ersichtlich, dass die Jetdicke zu berücksichtigen ist, da qualitätskritische Schweißnahtcharakteristiken in größerem Ausmaß vorliegen, wenn die Jetdicke zunimmt.

Magnetic pulse welding of metallic tubes – experimental investigation and numerical modelling

“…Zhang et al (2008) also observed excessive plastic deformation and spalling along the flyer–target joint interface in MPW AA6061 tubes and attributed the same to the generation of high intensity stress waves due to the application of a very high peak discharge current of 860 kA [23]. A jetting velocity of around 34.64 mm s −1 was also reported favourable to achieve good MPW joints between aluminium and steel sheets [24].…”

Studies on the Quality of Joints and Phenomena Therein for Welded Automotive Components Made of Aluminum Alloy—A Review

“…Affected by a collision angle, a point of collision (PoC) moves along the colliding surfaces. When the dynamic elastic limit of the material is exceeded, material flow results from the plastic deformation of the contact surfaces, and a stream of material is pushed ahead of the PoC [79,80]. This so-called jetting removes brittle oxide layers and surface contaminations from the surfaces, which are ejected either as a compact stream or as a dispersed cloud of particles (CoP) [81].…”