1,721,108 research outputs found
Repairing of an engine block through the cold gas dynamic spray technology
Get PDFIn the modern automotive industry, the maintenance of the vehicle during its life cycle is increasing
in importance due to both economical and environmental considerations. A new frontier is the reparation
of large parts, originally made by fusion, by the addition of material. The standard technique in the
field is the use of TIG welding, but in the last few years Cold Dynamic Gas Spray (CDGS) has started
to show many promises in supplanting TIG repairs. The main advantage of CDGS is the absence of
thermal stresses in the repaired zone with the elimination of thermal distension treatment of the part.
In this paper we study the use of CDGS to repair wear damage on a commercial aluminium engine
block in comparison with the standard repair procedure with TIG. The result obtained shows that
CDGS is an effective technology for industrial-level repair
Beta-Forging of Titanium Ti6Al4V Alloy Powders: Phase Evolution Modeling and Strain-Rate Relation
No full textMechanical Characteristics of Welded Joints of Aluminum Alloy 6061 T6 Formed by Arc and Friction Stir Welding
No full textButt welds formed by arc welding in inert gas with nonconsumable electrode (tungsten inert gas (TIG) welding) and by friction stir welding (FSW) from aluminum alloy AA6061 T6 are studied. Comparative analysis of the structures and mechanical properties of the welded joints is performed using the results of optical and electron microscopy, tensile tests, tests for residual bending ductility, and measurements of microhardness. The changes in the microstructure in different zones and the degrees of degradation of the mechanical properties after the welding are determined. It is shown that the size of the tool for the friction stir welding affects the properties of the welds. Quantitative results showing the relation between the microscopic behavior of the alloy and the welding-induced changes in the microstructure are obtained. Friction stir welding is shown to provide higher properties of the welds
Numerical and Experimental Analysis on selective Laser Post-Treatment of Cold Sprayed Titanium Coating
No full textCold gas dynamic spray is an innovative technology allowing the deposition of thin metallic layers on a bulk or sheet substrate. Titanium on aluminum deposition is very attractive to the aeronautic industry, due to the enhanced corrosion resistance and wear properties of titanium coating as well as its improved compatibility with CFRP, preserving the reduced cost of aluminum substrate. One main drawback, however, is related to the micro-porosity of the deposed layer, negatively affecting the corrosion barrier performance. In this paper, the effect of selective laser post-treatment on pure grade 2 titanium coatings on AA2020-T3 sheets was experimentally and numerically investigated. Morphological features, microstructure and chemical composition of the treated zone were assessed by means of optical microscopy, scanning electron microscopy and energy dispersive X-ray spectrometry. Microhardness measurements were also carried out to evaluate the mechanical properties of the treated coating. A numerical model of the laser treatment, based on a finite volume scheme, was implemented and solved to simulate the process and discuss the experimental outcomes. Obtained results highlighted the key role played by heat input and dimensional features on the effectiveness of the treatment
Experimental Study of the Forces Acting on the Tool in the Friction-Stir Welding of AA 2024 T3 Sheets
No full textIn this paper, AA 2024 T3-rolled sheets were joined in butt joint configuration through the friction stir welding process. Different joints were carried out varying the principal process parameters (i.e., tool welding speed and tool rotational speed). The aim of this work was the study and the experimental characterization of the influence of the process parameters on the forces acting on the tool during the FSW process. Furthermore, it was studied the correlation between the forces and the grain size, in particular with the extension of the heat-affected zone. Forces acting along the axis parallel to the tool are actually greater than those acting along welding direction. All the recorded forces are strictly dependant on the process parameters adopted. No correlation has been found between the grain dimension within the weld bead and the recorded forces, while the greater the forces, the narrower the extension of the heat-affected zone. �� 2014 ASM International
Tensile properties of a hot stretch formed Ti-6Al-4V alloy component for aerospace applications
No full textComprehensively considering the analysis results of the microstructure, hardness and tensile properties, different zones of a component for aircraft applications manufactured through hot stretch forming were studied. The differential thermomechanical story of each studied zone of the forging was taken into account. The results reveal that the different zones strain hardened in function of the degree of the strain and strain rate experienced during the forming, with the zones most stressed at the higher strain rate showing the best tensile properties and a loss of ductility. This phenomenon is not coupled with a visible change into the microstructure morphology of the processed material. © 2017. Published by Manufacturing Technology
Influence of the Heated-Bed Material on PLA Mechanical Properties and Energy Consumption in the FDM Process
Get PDFOn the Critical Technological Issues of Friction Stir Welding T-Joints of Dissimilar Aluminum Alloys
No full textIn this article, friction stir welded T-joints of innovative dissimilar aluminum alloys have been produced and tested with the aim to investigate the feasibility of using this joining technique, in this configuration, in the aerospace field with the final aim to save weight. The introduction of both this new welding technique and innovative alloys, such as AA 2198 and AA 6056, could allow making lighter and stronger structures.
Some experiments, carried out previously, have shown that the fixturing device, the tool geometry, and the tilt angle play a significant role in the joint soundness. A wide experimental characterization has been carried out on FSW T-joints of AA 6056 T4 extrudes to AA 2198 T3 rolled plates. The results attained allow to put in evidence some critical issues on the investigated configuration and can be considered as a further acquired knowledge in the understanding and the design of friction stir processes
Experimental characterization of thermal sprayed coatings on steel substrate
No full textThermal spray technology are increasingly used in industry to create harder coatings on mechanical
components to improve the wear properties or the corrosion resistance. In this paper two different coatings
sprayed on a steel surface with two different techniques, high-velocity oxygen fuel (HVOF) and air plasma spray
(APS), were studied. A whole experimental campaign was carried out in order to characterize the coatings and
investigate about adhesion to the surface and wear properties in different conditions. Furthermore coatings
with different thickness, in order to evaluate the attitude of these technologies to realize thick coatings, were
studied. The results obtained suggest that both the coating types have an optimal internal cohesion, a good
adhesion to the substrate and good wear resistance
Fused filament fabrication of polylactic acid/flax composites: Effects of infill strategy on dynamic and static behavior and energy consumption
No full textFused Filament Fabrication (FFF) is one of the most widely used Additive Manufacturing (AM) techniques, employing thermoplastic filament to create components. Among its many process parameters, the infill pattern plays a crucial role in determining both the mechanical performance and environmental footprint of printed parts, particularly in energy dissipation and damage behavior under impact. In this context, Natural Fiber Composites (NFCs), such as PLA reinforced with flax, are gaining interest due to their renewable origin, yet their low-velocity impact response and overall process sustainability remain underexplored. This study addresses these gaps by investigating the influence of infill pattern on the flexural and impact behavior of FFF-printed flax-reinforced PLA, while also assessing energy consumption during printing through a gate-to-gate Life Cycle Assessment (LCA). Results show that reducing the infill density of the Solid pattern by 20% leads to a 7.52% reduction in printing energy under constant conditions. Among all tested patterns at 80% infill, the Triangular pattern emerged as the most balanced option, offering favorable mechanical performance with a relatively low environmental impact. These insights aim to support more sustainable design strategies for prototyping and non-structural applications involving biocomposites produced by FFF
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