1,720,966 research outputs found
Laser-arc combined welding of aa5754 alloy
No full textLaser-arc combined welding of 5754 magnesium aluminium alloy was performed with the CO2 heat source and MIG torch. The effects of welding conditions on penetration depth, geometry, porosity and crack susceptibility were investigated. Concerning porosity suppression and key-hole stability, optimal process parameters were identified. The grain boundary wetting phenomenon was observed in the fused zone
Transfer mode effects on Ti6Al4V wall building in wire laser additive manufacturing
No full textThis paper analyses the metal transfer process dynamics to assess how weld pool, laser source and filler wire interact to establish a stable and smooth deposition. The investigation led to the definition of suitable manufacturing settings and process parameters. Satisfactory geometrical and microstructural properties were achieved for a 15-layer titanium alloy wall. (C) 2021 Society of Manufacturing Engineers (SME). Published by Elsevier Ltd. All rights reserved
Using Fundamental Parameters and Artificial Neural Network for Controlling the Laser Welding of Metals
No full textInfluence of shoulder geometry and coating of the tool on the friction stir welding of aluminium alloy plates
Full text linkFriction Stir Welding (FSW) has demonstrated a significant potential for joining low melting point non-ferrous metals in several joint configurations. During FSW metals are joined in the solid state due to the heat generated by the friction and flow of metal by the stirring action of a pinned tool.
This paper reports an experimental investigation on the effects of geometry and surface coating of the tool shoulder on the defectiveness, the microstructure and the microhardness of a 3 mm thick 5754H11 aluminium alloy butt weld.
During the experiments the diameter and slope of the shoulder varied. Moreover a tungsten carbide coated was tested. The pin geometry and dimensions were kept constant. Four different tools for shoulder geometry and coating condition were tested. The weld was characterized in terms of the bead morphology and the grain size.
The weld microhardness profile was measured for all the microstructural zones of the friction stir welding process.
The obtained results provide a deeper knowledge of the effect of the tool shoulder geometry and surface condition on the aluminium alloy weldability
Finite Element Model for Laser Welding of Titanium
No full textAbstractThis paper presents a finite element numerical analysis of the heat transfer in the laser welding process of Ti6Al4V titanium alloy. For sake of validation, 1.5 mm thick butt joints were made using a fiber laser. The finite element calculation of the process was carried out by a parametric design language (APDL) available in the ANSYS finite element code. The numerical modelling was conducted focusing the attention on the model of the laser-material interaction, which allowed to predict the temperature distribution during the thermal cycle and the related phase transformations. The parametric solution was implemented in order to make it suitable for different welding conditions. The numerical model was calibrated both by comparison between the weld transverse cross section of and the thermal cycles detected by thermocouples during welding. Then the simulation was conducted and the evolution of the temperature distribution during the process was calculated. The comparison between experimental and numerical results stressed the evidence of the suitability of the here-presented model for the simulation of the laser welding process of titanium alloys
Mechanical and microstructure analysis of AA6061 and Ti6Al4V fiber laser butt weld
No full textDissimilar metal welding involves the joining of two or more different pure metals or alloys, usually by melting and mixing and often with the addition of filler metal. There are several types of dissimilar metal welds including stainless steel, either as base metal or as filler metals. Dissimilar metal joints have distinctive features because of differences in the chemical composition of base metal and filler material. Their alloying elements will diffuse intensely during welding. The structures near the fusion line are very complex. Despite of great potentiality in aircraft and automotive industries, dissimilar joining of hybrid Al-Ti structures is often challenging because of the unavoidable formation of brittle intermetallic compounds, mixing of molten phases, and significant differences in material properties. In this work, dissimilar 2 mm thickness AA6000 and Ti6Al4V butt joints were produced by shifting an Yb fiber laser beam on the upper surface of the Ti sheet. Neither filler wire nor groove preparation was adopted. Different working conditions and seam shapes were assessed. The welds were characterized in terms of metallurgical and mechanical behaviors
Study on arc and laser powers in the hybrid welding of AA5754 Al-alloy
No full textIn this paper a new generation of fiber laser assisted by a MIG source was used to weld AA5754-H111 aluminum alloy in 3. mm thick butt configuration. The effects of laser and arc powers on the weld geometry and properties were studied. Weld geometry and porosity were measured. The microstructure was investigated by optical microscope and Vickers micro-hardness was taken. The residual stress close to the heat affected zone was measured by the incremental hole-drilling method. Eventually, the tensile test was conducted in order to compare the mechanical properties of the weld with those of the parent metal.For the first time the sensitiveness of the hybrid welding of the 5754 aluminum alloy to the arc and laser powers was demonstrated. Higher laser power favored the stability of the process and provided good structural and geometrical properties of the weld. Further investigation can be performed in order to optimize the weld soundness and the energy efficiency of hybrid welding an aluminum alloy using a fiber laser
ANN modelling to optimize manufacturing processes: the case of laser welding
No full textIn this work, an artificial neural network (ANN) was implemented to investigate the main effects of process parameters on the laser welding process quality. A high brightness Yb fiber laser was used to carry out the analysis. Full penetration autogenous welding of 6 mm thick AA5754 aluminum alloy sheets was performed in butt configuration. The welding speed and the shielding gas varied in the experimental plan. The process quality was analyzed by visually inspecting the bead appearance. The ANN modeling code was built by Neural Tools (Excel add-in) – Palisade Corporation®. The statistical estimation revealed the relationship of the process parameters with the weld geometry, which provides a deeper understanding of the welding process. Eventually, the usefulness of ANN modeling for optimizing the quality of manufacturing processes was demonstrated
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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