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See detailEVALUATION OF THE JOINT BASED ON DIFFERENT SURFACE CONDITIONS FOR ALUMINUM-POLYAMIDE LASER WELDING
Amne Elahi, Mahdi UL; Koch, Marcus; Plapper, Peter UL

in Journal of Laser Applications (2021)

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface ... [more ▼]

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface treatment of the metal has a decisive effect on the joint quality and thus on the mechanical properties. In the present study, different mechanical and laser-based surface treatments have been investigated to develop diverse surface conditions on aluminum. Abrasive blasting and laser ablation were used to increase the surface roughness, while abrasive polishing and laser polishing were applied to minimize the surface roughness. In contrast to abrasive surface treatments, laser-based ones were implemented to create artificial oxide layers on the aluminum surface. The surface structures of pretreated samples have been studied with scanning electron microscopy and roughness test. The laser welding of pretreated aluminum with polyamide was achieved with the heat conduction joining technique. To enlarge the welding area and control the heat input, spatial and temporal modulations of the laser beam were implemented. Finally, a single lap tensile-shear test, microscopic analysis of fractured surfaces, and welding cross sections were employed to evaluate the joints. Results show that the presence of an artificial aluminum oxide layer and low roughness are essential to achieve a superior joint between aluminum and polyamide (improvement of approximately 58% in the shear load of the joint compared to as-received welded samples). The cross section of the superior joint which is the laser-polished aluminum welded to polyamide is studied with transmission electron microscopy. [less ▲]

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See detailPre and post-treatments to improve weldability and mechanical properties of Aluminum-Polyamide laser welded specimens
Amne Elahi, Mahdi UL; Koch, Marcus; Heck, Mike et al

in Procedia CIRP (2020), 94

The laser polishing surface treatment is a prerequisite for enhanced weldability that is enabled by superior adhesion between the weldments. The paper describes the laser polishing process of the aluminum ... [more ▼]

The laser polishing surface treatment is a prerequisite for enhanced weldability that is enabled by superior adhesion between the weldments. The paper describes the laser polishing process of the aluminum surface to develop a relatively thick and porous artificial aluminum oxide layer. Microscopic observation shows the laser polishing process significantly improves the adhesion of molten polyamide to the aluminum surface. Besides, the shear load of the pretreated joints is much higher than that of as-received ones. However, for the majority of the welded samples, the failure happens at the polyamide near the interface of aluminum/polyamide due to the thermal effect and structural changes of polyamide during the welding process. By applying the post-treatment of the welded specimens with different cycles, the mentioned failure mechanism is not observed anymore. Therefore, the mechanical properties of the joint will be improved and reach to the limits of the base materials. [less ▲]

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See detailLaser polishing of Aluminum and Polyamide for dissimilar laser welded assemblies
Amne Elahi, Mahdi UL; Koch, Marcus; Plapper, Peter UL

Scientific Conference (2019, June 27)

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See detailDissimilar Laser Micro-Welding of Nickel Wire to CuSn6 Bronze Terminal
Amne Elahi, Mahdi UL; Plapper, Peter UL

in Transactions of the Indian Institute of Metals (2018)

In the present study, the laser welding of wire to flat geometry for miniature electromechanical hybrid components has been investigated. Considering the geometry of parts to be welded and also ... [more ▼]

In the present study, the laser welding of wire to flat geometry for miniature electromechanical hybrid components has been investigated. Considering the geometry of parts to be welded and also requirement of mechanical properties, spatial modulation of the laser beam was needed to be implemented to achieve a sound joint. Tensile-shear test and optical microscopy were employed to represent the mechanical properties and melt pool geometry of the joints. All welds were done by power modulation of the laser beam to better control the energy input at several feed rates and three different beam trajectories. Results showed that the shear load of the joint could be controlled by feed rate and the trajectory of the laser beam. Considering the material combination of the study that were nickel and CuSn6 bronze, which represented solubility in solid state, a joint stronger than base wire metal was achieved by defining a proper spatial modulation and feed rate of the laser beam. [less ▲]

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See detailLaser micro-welding of wire to flat geometry for dissimilar materials in an electromechanical application
Amne Elahi, Mahdi UL; Plapper, Peter UL

Poster (2018, September 11)

In the presented study, the laser welding of wire to flat geometry for miniature electromechanical hybrid components has been investigated. Laser welding offers variety of advantages compared to the ... [more ▼]

In the presented study, the laser welding of wire to flat geometry for miniature electromechanical hybrid components has been investigated. Laser welding offers variety of advantages compared to the current joining processes for this application however, considering the geometry of parts to be welded also mechanical properties requirement, an accurate spatial modulation of laser beam should be implemented to achieve a sound joint. Tensile shear test and optical microscopy were employed to represent the mechanical properties and melt pool geometry of the joint. All welds were done by power modulation of the laser beam to better control the energy input at several feed rates and three different beam trajectories. Results show that the shear load of the joint can be controlled by feed rate and the trajectory of the laser beam. The material combination of the study (Nickel and CuSn6), represents solubility in solid state therefore, by defining a proper spatial modulation of the laser beam a joint stronger than base wire metal is achievable. Figure 1 represents schematics of weld components. [less ▲]

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