Browse Topic: Brazing

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The Joint AWS/SAE Committee on Automotive Welding was organized on January 16, 1974, for the primary purpose of facilitating the development and publication of various documents related to the selection, specification, testing, and use of welding materials and practices, particularly for the automotive and related industries. A secondary purpose is the dissemination of technical information.
Metals Technical Committee
Impact Mechanism of Multiple Major Welding Parameters on Mechanical Properties of Laser Brazing Lap Joint of Galvanized Steel for Vehicle2017-01-50109/22/2017
In order to research the effect of process parameters (laser power, welding speed, wire-feed speed, spot diameter) on mechanical properties of Zn-coated Steel Laser Brazing Lap Joint for vehicle, the influence of welding parameters on energy input of brazing seam cross section was theoretically analyzed, and then a great number of laser brazing experiments of 0.7mm galvanized steel was carried out. After that, the tensile strength and micro-hardness tests were also done for well-formed joints of galvanized steel formed in the laser brazing. The results show that joints with good mechanical properties and surface morphology can be formed when laser power is in the range of 2500-3200W and the other parameters keep in a specified range. Joint performance significantly reduces when the value of wire-feed speed exceeds 3.0m/min for that a wider brazing seam cross section can’t be formed. And tensile strength of the joint drops steeply when welding speed exceeds 50mm/s, because the solid-liquid surface tension between the brazing filler metal and the base metal increases. When the spot diameter increases within the appropriate range, the decrease of the energy density slows down the cooling rate of the brazing filler metal, which makes the mechanical properties of the brazing seam maintain a good condition. Moreover, under the same welding parameters, the micro-hardness anywhere inside the weld joint is uniform, which testifies the mechanical performance of the brazing seam is safe and stable.
Liu, H.J.Zhang, X.D.
This specification covers an aluminum brazing flux in the form of powder.
AMS B Finishes Processes and Fluids Committee
Prefluxed Aluminum Tube for Brazed Automotive Heat Exchangers9501162/1/1995
Provision of a thin layer of zinc on aluminium to provide the fillets during brazing has been described previously [1]. The process for zinc coating of the extruded aluminium multiport tubes has been further enhanced by utilisation of the zinc layer to carry flux for subsequent brazing operations, thereby making it possible to produce brazed heat exchanger assemblies utilising the thin zinc layer, without the need for a separate fluxing operation prior to brazing. The flux is applied directly onto the molten zinc coating where it becomes mechanically locked in position when the zinc freezes. Because of this action, the flux cannot be easily dislodged, unlike other techniques where powdered flux has been sprayed directly upon the aluminium tube surface or a fused flux has been applied to the tube surface. The prefluxed product can readily be handled and subjected to simple forming operations without dislodging the flux. Flux can be adhered to zinc coatings as thin as two micrometers and below, which is somewhat lower than required for the zinc-based joining process but, in this form, the flux layer is suitable for enhancement of conventional Al: Si brazing technology. In this case, the zinc is diffused into the aluminium tube wall during brazing to provide enhanced corrosion resistance. When the flux is applied to a heavier zinc coating, the need for Al:Si brazing is avoided, with the zinc providing the braze fillets through diffusion and partial melting of the diffused layer at normal braze temperatures. The technology also offers potential for brazing in normal air rather than nitrogen atmospheres and more simplified braze cycles can be used, where the need to drive off water from the flux is reduced. It also has the added advantage that the flux is carried directly into the joint area where it will melt and act in situ obviating the requirement to melt and flow into the joints to become effective during brazing. Furthermore, the need to apply extra flux to certain joint areas can be eliminated.
Morley, E. J.Börjeson, R.
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