Topic
Heat-affected zone
About: Heat-affected zone is a research topic. Over the lifetime, 18787 publications have been published within this topic receiving 231744 citations.
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TL;DR: In this article, the authors investigated the welding deformation in low carbon steel thin-plate joints induced by laser beam welding and CO 2 gas arc welding by means of both numerical simulation technology and experimental method in the current study.
107 citations
TL;DR: In this article, a three-dimensional numerical heat transfer and fluid flow model was developed to examine the temperature profiles, velocity fields, weld pool shape and size, and the nature of the solidified weld bead geometry during GMA fillet welding.
Abstract: Gas metal arc (GMA) fillet welding is one of the most important processes for metal joining because of its high productivity and amiability to automation. This welding process is characterized by the complicated V-shaped joint geometry, a deformable weld pool surface, and the additions of hot metal droplets. In the present work, a three-dimensional numerical heat transfer and fluid flow model was developed to examine the temperature profiles, velocity fields, weld pool shape and size, and the nature of the solidified weld bead geometry during GMA fillet welding. The model solved the equations of conservation of mass, momentum, and energy using a boundary fitted curvilinear coordinate system. Apart from the direct transport of heat from the welding arc, additional heat from the metal droplets was modeled considering a volumetric heat source. The deformation of the weld pool surface was calculated by minimizing the total surface energy. Part I of this article is focused on the details of the numerical model such as coordinate transformation and calculation of volumetric heat source and free surface profile. An application of the model to GMA fillet welding of mild steel is described in an accompanying article (W. Zhang, C.-H. Kim and T. DebRoy, J. Appl Phys. 95, 5220 (2004)).
106 citations
TL;DR: In this article, the effects of the inclination angle, interwire distance and welding current ratio between the leading wire and the trailing wire on bead formation in high speed welding are investigated, and the undercut and humping bead are attributed to the irregular flow of molten metal towards the rear part of the weld pool.
Abstract: Undercut and humping bead are the common defects that limit the maximum welding speed of tandem pulsed gas metal arc (GMA) welding. In order to increase the maximum welding speed, effects of the inclination angle, interwire distance and welding current ratio between the leading wire and trailing wire on bead formation in high speed welding are investigated. The undercut and humping bead is attributed to the irregular flow of molten metal towards the rear part of the weld pool. This irregular flow can be prevented by the trailing wire with a push angle from 5° to 13° , which provides an appropriate component of arc force in the welding direction. The irregular flow is also related to the distance between the leading wire and the trailing wire, and the flow becomes regular when the distance is in the range 9–12 mm. Moreover, the stabilisation of the bulge of the weld pool between the two wires, the presence of enough molten metal below the trailing arc, and the reduced velocity of molten metal flow ...
106 citations
TL;DR: In this article, the ability to relate weld strength to the welding process data, namely dissipated power and displacement of the sonotrode, in ultrasonic welding of thermoplastic composite parts with flat energy directors, is described.
Abstract: Ultrasonic welding of thermoplastic composites is a very interesting joining technique as a result of good quality joints, very short welding times and the fact that no foreign material, e.g. a metal mesh, is required at the welding interface in any case. This paper describes one further advantage, the ability to relate weld strength to the welding process data, namely dissipated power and displacement of the sonotrode, in ultrasonic welding of thermoplastic composite parts with flat energy directors. This relationship, combined with displacement-controlled welding, allows for fast definition of optimum welding parameters which consistently result in high-strength welded joints.
106 citations
TL;DR: In this paper, the formation of ultrasonic spot welds of AA6111-T4 was investigated using a single-transducer unidirectional wedge-reed welder.
Abstract: The formation of ultrasonic spot welds of AA6111-T4 has been investigated using a single-transducer unidirectional wedge-reed welder. The evolution of weld microstructures and weld strength due to anvil cap geometry and welding energy was studied. The variations in lap-shear failure load and weld microstructures as a function of welding energy were only slightly influenced by the changes in the anvil cap geometry. Weld failure in lap-shear tensile tests occurs by interface fracture for low energy welds and by button formation for high energy welds. Initially, microwelds or weld islands several microns in diameter are generated presumably at asperities of the two pieces being joined. As the welding energy increases, the weld interface can change from a planar to a wavy morphology and the weld strength increases. Deformation wakes and bifurcation are ubiquitous in strong welds. Microporosity is observed at the periphery of growing weld islands and along the flow lines associated with the wavy deformation microstructures. Grain growth occurs inside the weld zone after isothermal annealing. However, the porous microstructure at the weld interface is not affected by isothermal annealing. Ultrasonic spot welding of AA6111-T4 aluminum was found to be insensitive to variations in anvil cap size and the knurl patterns investigated in this research.
106 citations