For joining metallic materials for battery applications such as copper and stainless steel, laser beam micro welding with beam sources in the near-infrared range has become established in recent years. In laser beam micro welding, spatial power modulation describes the superposition of the linear feed motion with an oscillating motion. This modulation method serves to widen the cross-section of the weld seam as well as to increase the process stability. Temporal power modulation refers to the controlled modulation of the laser power over time during the welding process. In this paper, the superposition of both temporal and spatial power modulation methods is presented, which enables a variable control of the weld penetration depth. Three weld geometries transverse to the feed direction are part of this investigation: the compensation of the weld penetration depth due to the asymmetric path movement during spatial power modulation only, a W-shaped weld profile, and a V-shaped. The weld geometries are investigated by the bed on plate weld tests with CuSn6. Furthermore, the use of combined power modulation for welding tests in butt joint configuration between CuSn6 and stainless steel 1.4301 with different material properties is investigated. The study shows the possibility of precise control of the welding depth by this methodology. Depending on the material combination, the desired regions with maximum and minimum welding depth can be achieved by the control of local and temporal power modulation on the material surface.
Due to the change in grain size during laser processing in the heat-affected zone and the solidifying material, the potential of cracking, surface hardening, and decrease in weldability, corrosion resistance and fatigue life may result. It is shown that through combining state-of-the-art temperature simulation of laser processes with thermo-mechanical volume averaging grain formation simulation, the resulting grain density can be predicted within the order of magnitude found in the two experiments carried out for laser fusion cutting and spot welding of A356. However, fundamental knowledge about the grain density function during rapid solidification, the prediction of the transition from epitactic growth to globular grains and defined validation experiments are needed in order to provide a realistic virtual microstructure.Aufgrund der Ä nderung der Korngrö ße bei der Laserbearbeitung in der Wä rmeeinflusszone und dem erstarrenden Material wird das Potenzial der Rissbildung, Oberflä chenhä rtung und Abnahme der Schweißbarkeit, Korrosionsbestä ndigkeit und Ermü dungslebensdauer gegeben. Es zeigt sich, dass durch die Kombination von modernster Temperatursimulation von Laserprozessen mit einem thermomechanischen Volumenmittelungsansatz zur Kornbildungssimulation die resultierende Korndichte in der Grö ßenordnung vorhergesagt werden kann, die in den beiden durchgefü hrten Experimenten Laserstrahlschneiden und Punktschweißen von A356 gefunden wurde. Grundsä tzliches Wissen ü ber die Korndichte bei der schnellen Erstarrung, die Vorhersage des Ü bergangs vom epitaktischen Wachstum zu kugelfö rmigen Kö rnern und definierte Validierungsexperimente fehlen jedoch noch, um eine realistische virtuelle Mikrostruktur zu berechnen.
The laser-spot welding process of aluminum alloy 1050A with a limited thickness is observed with the x-ray phase contrast method to investigate the melt dynamic especially when the melt penetrates the material. The laser-spot welding is investigated with two different wavelengths of the laser beam source: 515 and 1030 nm to investigate the influence of the absorptivity. The melt progressively penetrates the material during the spot-welding process until reaching the bottom side of the material and when the melt penetrates the lower side of the material, the so-called “lens-like” melt appears at the lower side due to the surface tension. At a comparable beam intensity value, the oscillation of the “lens-like” melt at the lower side of the material is driven by the expansion of vapor capillary. This expansion occurs inside of the material and directly above the “lens-like” melt. The shape of the expanded vapor determines the volume as well as the geometry of the resulting melt volume. Furthermore, the transition from the heat conduction welding mode to the keyhole welding mode is investigated by defocusing the laser beam for the beam source with a 515 nm wavelength. At a given variation, a clear difference between either mode is observed with the x-ray phase contrast method.
Using spatial and temporal power modulation, new degrees of freedom can be gained in process efficiency, quality and seam geometry, which are of particular interest for the increasing requirements of electromobility in the production of battery cells and power electronics. Through the targeted synchronization of these two compensation methods, synergies can be used and any limitations that may arise can be overcome.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.