1,721,029 research outputs found
Laser Welding of Thin Copper and Aluminum Sheets: Feasibility and Challenges in Continuous-Wave Welding of Dissimilar Metals
No full textThe present paper defines process windows for laser welding of thin copper and
aluminum sheets in Al-Cu and Cu-Al lap-joint configurations, exploiting different
process strategies and parameters. A single-mode continuous-wave (CW) laser source
was exploited with both linear and wobbling strategies. In both cases the influence of
several parameters, such as, laser power, spot dimensions and scanning speed on the
resulting microstructure and joint strength was analyzed. The influence of one, two and
three parallel beads on the maximum shear strength was also evaluated. The optimum
process configurationswere finally determined based onmaximum joint strength in shear
tests and the mixing of the two parent metals occurring after welding was determined by
means of SEM-EDS analysis
Dissimilar laser welding of copper and aluminum alloys in multilayer configuration for battery applications
No full textThe joining process of copper and aluminum has become a key topic especially in the field of electro-mobility due to the fact that batteries, based especially on pouch Li-ion cells, are often manufactured in a way that involves joining together copper and aluminum tabs that constitute the anode and the cathode. Car manufacturers, in order to create more compact and performing batteries, are looking to stack more cells in small spaces and then weld the copper and aluminum tabs in multilayer configuration. However, welding those materials poses several challenges due to their differences in chemical and physical properties, such as melting temperature, thermal conductivity, and thermal expansion coefficient. One of the main challenges is represented by the formation of hard and brittle intermetallic compounds, which reduce both mechanical and electrical properties. The present paper addresses dissimilar laser welding of copper and aluminum in multilayer configuration by means of an infrared laser source equipped with galvanometric scanner optics, which allows us to obtain a spatial beam oscillation (circular wobbling) of the beam. The results confirmed that a larger wobbling amplitude does not enhance the properties of the connection. A maximum tensile load of about 1000 N and low electrical contact resistance were obtained with optimized parameters, while the presence of harder and brittle intermetallic compounds was reduced. Scanning electron microscope-energy dispersive x-ray spectrometer analysis confirmed the results obtained with the metallographic and mechanical tests
Continuous laser welding with spatial beam oscillation of dissimilar thin sheet materials (Al-Cu and Cu-Al): Process optimization and characterization
No full textContinuous laser welding with spatial beam oscillation was investigated as a method of joining combinations of thin copper and aluminum sheets. Welding of these materials is required for manufacturing of electronic components due to their physical properties. Welding of dissimilar metals such as Al-Cu with conventional manufacturing techniques is difficult due to unavoidable formation of brittle intermetallic compounds, which reduce both the mechanical and electrical properties of the joint. The aim of this work was to understand how process parameters such as laser power, welding speed and wobbling amplitude affected the weld seam, making it possible to determine which parameters were of greatest influence on the mechanical and electrical properties of the resulting joint. Both the width and penetration of the weld seam were strongly correlated to the wobbling amplitude. The ultimate tensile strength of both configurations (Al-Cu and Cu-Al) was as high as 100 kgf with optimized process parameters. Micro-hardness tests showed an increase in hardness near the molten area. The temperatures attained during welding were approximately 40 °C at 10 mm from the weld seam. Low electrical contact resistance and high tensile strengths were obtained with the same parameters
Continuous laser welding with spatial beam oscillation of dissimilar thin sheet materials (Al-Cu and Cu-Al): Process optimization and characterization
Full text linkContinuous laser welding with spatial beam oscillation was investigated as a method of joining combinations of thin copper and aluminum sheets. Welding of these materials is required for manufacturing of electronic components due to their physical properties. Welding of dissimilar metals such as Al-Cu with conventional manufacturing techniques is difficult due to unavoidable formation of brittle intermetallic compounds, which reduce both the mechanical and electrical properties of the joint. The aim of this work was to understand how process parameters such as laser power, welding speed and wobbling amplitude affected the weld seam, making it possible to determine which parameters were of greatest influence on the mechanical and electrical properties of the resulting joint. Both the width and penetration of the weld seam were strongly correlated to the wobbling amplitude. The ultimate tensile strength of both configurations (Al-Cu and Cu-Al) was as high as 100 kgf with optimized process parameters. Micro-hardness tests showed an increase in hardness near the molten area. The temperatures attained during welding were approximately 40 degrees C at 10 mm from the weld seam. Low electrical contact resistance and high tensile strengths were obtained with the same parameters
The influence of laser pulse shape and separation distance on dissimilar welding of Al and Cu films
No full textPulsed Nd:YAG laser welding of Aluminum-Copper (Al-Cu) electrical connections has been investigated, focusing attention on the definition of optimal process parameters to achieve low thickness joints by varying the laser pulse shape and separation distance. Heterogeneous joints comprising Al and Cu are often required in electrical applications due to the inherent characteristics of these materials. Nevertheless, welding of dissimilar metals such as Al and Cu involves many challenges due to the high reflectivity and poor weldability between the materials, which produce brittle microstructural compounds that lead to a reduction in mechanical and electrical properties. Metallurgical, mechanical, electrical and thermal analyses have been performed on Al-Cu lap joints to evaluate the effect of different pulse separation distances and shapes on the resulting weld seam. Process optimization achieved welded joints with a low penetrating depth and maximum tensile loads of over 110 kgf. Preliminary experiments were carried out to establish a process parameter feasibility window. A first set investigated variations in pulse energy and distance for square pulses, while a second set saw variation of the pulse energy, pulse distance and pulse shape. It was found that an optimal pulse distance for a specific parameter set exists, while a pulse shape that includes material preheating produces better results in terms of mechanical strength and electrical resistance than a pulse with high initial peak power
Hardness Penetration Depth Prediction in the Grind-Hardening Process through a Combined FEM model
Full text linkDove va la scrittura. Indagine-monitoraggio sulle scritture di sé in Italia
No full textL'indagine intende esplorare la molteplicità delle forme laboratoriali di scrittura individuale e collettiva presenti, in particolare nell'ultimo decennio, nel territorio nazionale. Diviene una base interessante per esaminare bisogni/domande e risposte locali sulle pratiche autobiografiche in Italia
Laser dissimilar welding of highly reflective materials for E-Mobility applications
No full textManufacturing technologies for E-Mobility applications have gained undoubted interest over recent years due to a large consensus towards hybrid and electric vehicles that characterize modern automotive requirements. Among the various components that make up an electric vehicle, batteries and electric motors represent the “heart” of this new class of transport and, given their constituting materials, require new and strategic manufacturing processes. With particular reference to joining processes, both batteries and electric motors require the application of welding techniques capable of dealing with lightweight and electrically conductive metals such as aluminum and copper alloys, often in dissimilar configurations. Among modern welding technologies, laser-based ones have proven to be a suitable solution both in low- and high-productivity environments. Within this context, the present chapter provides a comprehensive review of laser-based joining techniques for battery and electric motor production in the field of E-Mobility, giving an overview of what to expect in terms of equipment, results, challenges and limitations. Analysis of the state of the art in these applications is developed based on two main parameters: the wavelength and temporal profile of the radiation. In line with this distinction, applications of infrared, green and blue laser sources are considered, together with continuous-wave, long-pulse and short-pulse regimes
New Possibilities in the Fabrication of Hybrid Components with Big Dimensions by Means of Selective Laser Melting (SLM)
No full textAbstractThe application of laser technology to welding of dissimilar AISI316 stainless steel components manufactured with selective laser melting (SLM) and traditional methods has been investigated. The role of laser parameters on weld bead formation has been studied experimentally, with particular attention placed on effects occurring at the interface between the two parts. In order to assess weld bead characteristics, standardised tensile tests were carried out on suitable specimens and the fracture zone was analysed. The results highlighted the possibility of exploiting suitable process parameters to appropriately shape the heat affected and fusion zones in order to maximise the mechanical performance of the component and minimise interactions between the two parent metals in the weld bead
Structure, phase composition and microhardness of vacuum-arc multilayered Ti/Al, Ti/Cu, Ti/Fe, Ti/Zr nano-structures with different periods
No full textThe microstructure, phase composition and microhardness of multilayered Ti/Al, Ti/Cu, Ti/Fe and Ti/Zr condensates produced on stainless steel substrates via vacuum-arc evaporation of pure metals were studied. The sublayer periods (Λ) were regulated in the range 80–850 nm by varying the vacuum discharge current and the duration of the successive depositions of metallic plasma onto the substrates while maintaining the total deposition time constant. The regularity of the obtained nanostructures was investigated by scanning and transmission electron microscopy while phase compositions were identified with X-ray diffraction (XRD) analysis in order to evidence the presence of interdiffusion and the amount of intermetallics. Condensates cross sections were mechanically characterized by means of microhardness tests. Measurements were correlated to the periods and to the presence of intermetallics
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