In this study, a systematic investigation on the effect of welding conditions on longitudinal bending and angular distortions generated in welded thin plate was experimentally performed with a focus ...on whether or not the weld buckling distortion occurs. Real-time measurements of temperature profiles and distortion behavior during welding of thin plate were also performed for a more detailed understanding of generation process of weld distortion in thin plate. As the results, longitudinal bending distortion monotonically increases, in which the degree is different depending on the plate thickness, with the weld heat input. Meanwhile, angular distortion does not show a linear increase with the weld heat input and can be arranged coordinately by a curve convex to the parameter of mechanical melting zone, which was proposed based on the theory of inherent strain by authors in previous study, when the weld buckling distortion does not occur. In this regard, however, angular distortion also approximately monotonically increases with either the weld heat input or the parameter of mechanical melting zone, when the weld buckling distortion occurs. This is because the angular distortion-generation process proceeds in the following two stages; angular distortion is primary generated due to inhomogeneous temperature distribution through thickness during welding and secondary in association with buckling behavior during cooling process after welding. This secondary stage results in buckling-induced large angular distortion in welded thin plate. It was thus clarified that it is important to understand the generation characteristics of weld buckling-induced inherent stress and strain especially in the secondary stage for accurate predicting and controlling the weld buckling distortion in thin plate.
Heat source modelling based on weld arc physics has been developed for the more accurate numerical simulation of weld residual stress and distortion. Computational simulation of tungsten inert gas ...arc plasma based on mathematical modelling of the heat transfer from arc plasma to a welded plate is performed to obtain a more precise temperature distribution during welding. The temperature distribution obtained is used for a large deformation thermal elastic-plastic stress analysis of weld residual stress and distortion. In addition, the effects of welding process conditions on weld residual stress and distortion are examined considering weld penetration with the arc plasma process and verified experimentally. Finally, the effectiveness of arc physics based heat source modelling for numerical simulation of the weld residual stress and distortion is evaluated.
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The industrial application range of welded wood so far has been limited to interior use because of its poor moisture resistance. Influences of some welding and wood parameters such as welding ...pressure, welding time, and heartwood/sapwood on water resistance of Scots pine (Pinus sylvestris)
were investigated. An X-ray Computed Tomography scanner was used to monitor density change in weldlines during water absorption-desorption. Axial samples measuring 200 mm × 20 mm × 20 mm from Scots pine were welded and placed standing in 5-mm-deep tap water. Then they were
taken out of the water one at a time and scanned at 10-min intervals until the first crack appeared in the weldline where the two parts of each specimen made connection. Results showed that the X-ray Computed Tomography can be used as an effective tool to study welded wood. Welding pressure,
welding time, and heartwood/sapwood showed significant effect on length and location of the crack in the welded zone. Data evaluation showed that combination of 1.3 MPa welding pressure, 1.5 s welding time and using heartwood led to highest moisture resistance, which produced only a very short
crack in the beginning of the weldline.
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Results of investigation into the effect of welding conditions and microstructure of welded components on the course of the welding process and the quality of diffusion-welded joints in specimens of ...VT14 titanium alloy are presented. The results show that, depending on the combination of the microstructure of the components and the welding temperature, the formation of the welded joint is controlled by the activation of the contact surfaces and by the development of the stage of volume interaction or physical contact.
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We investigate how welding conditions affect the arc in TIG welding with a constricted nozzle by numerical simulation using an axial-symmetric two-dimensional model. When helium is used as a ...shielding gas, the effect of the constricted nozzle is more remarkable than argon. The heat flux to the center of the anode surface increases more with a higher welding current. This feature is suitable for pulsed welding. Even if an electrode is consumed and its tip angle is changed, a stable arc plasma and heat intensity are obtained.
This study focuses on the opening mode of induction bends; this mode represents the deformation outside a bend. Bending experiments on induction bends are shown and the manner of failure of these ...bends was investigated. Ruptures occur at the intrados of the bends, which undergo tensile stress, and accompany the local reduction in wall thickness, i.e. necking that indicates strain localization. By implementing finite element analysis (FEA), it was shown that the rupture is dominated not by the fracture criterion of material but by the initiation of strain localization that is a deformation characteristic of the material. These ruptures are due to the rapid increase in local strain after the initiation of strain localization and suddenly reach the fracture criterion. For the evaluation of the deformability of the bends, a method based on FEA that can predict the displacement at the rupture is proposed. We show that the yield surface shape and the true stress-strain relationship after uniform elongation have to be defined on the basis of the actual properties of the bend material. The von Mises yield criterion, which is commonly used in cases of elastic-plastic FEA, could not predict the rupture and overestimated the deformability. In contrast, a yield surface obtained by performing tensile tests on a biaxial specimen could predict the rupture. The prediction of the rupture was accomplished by an inverse calibration method that determined the true stress-strain relationship after uniform elongation.
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Experience with using Kemppi FastMig X 450 semi-automatic welding equipment in consumable electrode welding in the pulsed conditions of the structures for important applications made of aluminium ...alloys is presented. Positive results have been obtained with the quality of welded joints of the working wheel of oil turbine pumps and the labour content of welding operations has been reduced.
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