Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/02—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape
  • B23K35/0222—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by mechanical features, e.g. shape for use in soldering or brazing
  • B23K35/0233—Sheets or foils
  • B23K35/0238—Sheets or foils layered
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
  • B23K35/24—Selection of soldering or welding materials proper
  • B23K35/30—Selection of soldering or welding materials proper with the principal constituent melting at less than 1550°C

Definitions

• This invention relates to the production of flexible multilayered strip and, in particular, to the production of flexible multilayered brazing foils formed of rapidly solidified homogeneous metal foil joined to a ductile substrate.
• Brazing is a process for metallurgically bonding materials, often of dissimilar compositions, to each others at temperatures above about 450°C.
• a filler metal that has a melting point lower than that of the base material parts to be joined is interposed herebetween and the assembly is then heated to a temperature sufficient to melt the filler metal. Upon cooling, a strong joint is formed.
• brazing is commonly employed in the manufacture of a wide variety of products such as heat exchangers, cemented carbide tipped tools, bicycle frames, electrical products, etc.
• brazing fillers are employed in powder, ribbon, wire or wrought form.
• Improved brazing foils have been formed by rapid solidification techniques. These foils possess the ability to substantially reduce the number of failed joints because of improved homogeneity resulting from the rapid solidification process. Examples of such improved materials are disclosed in U.S. Patent Nos. 4,448,852 and 4,489,136.
• rapidly solidified brazing foils exhibit loses in relative ductility as the foil thickness increases and especially at foil thicknesses of greater than about 75-100 ⁇ m. Accordingly, there are applications which, because of the configurations of the brazed joint (especially those requiring a brazing filler-metal thickness larger than about 75 ⁇ m) require either special handling of the rapidly solidified brazing foil or, in some instances, require the selection of an alternative, inferior brazing material.
• the present invention is directed to multilayered products, in particular multilayered brazing foils, which comprise a rapidly solidified, homogeneous alloy foil metallically bonded to a substrate, wherein the substrate is capable of undergoing a substantial degree of plastic deformation without any substantial degradation of its ductility, and wherein the integrity of the foil layer is maintained.
• the present invention is directed to a process for producing multilayered products, in particular multilayered brazing foils, which comprises the steps of: arranging a rapidly solidified, homogeneous alloy in contact with a substrate capable of undergoing a substantial degree of plastic deformationswithout experiencing a substantial degradation of the ductility thereof; and applying heat and pressure to the alloy and substrate at a temperature and pressure in an amount and for a time sufficient to cause the substrate to undergo plastic deformation and to create metallic bonding between the alloy and the substrate.
• bonding is accomplished by a roll bonding process to produce continuous, multilayered brazing strip.
• the process comprises the steps of selecting a particular composition of the requisite elements in the desired proportions, melting and homogenizing the same, and depositing the molten compositions onto a chill surface, such as rapidly rotating cylinder, to quench the composition.
• Rapid solidification as used herein means the application of a quench rate of at least about 10 5 °C/sec.
• the products resulting from this process may be crystalline or amorphous, but regardless of their structure, they are homogeneous.
• the products are in foil form; that is, they have a thickness that is small relative to the width and length of the product. Most preferably, the foil is in the form of ribbon.
• the brazing strips of the present invention overcome a long-felt need in the industry to produce thick, ductile brazing strip from compositions which are inherently brittle in conventional form or in thick (A 100 ⁇ m) rapidly solidified foil from.
• Most brazing alloys contain a large concentration of metalloid elements such as Si, B, and P which form brittle intermetallic compounds upon crystallization.
• the present invention advantageously utilizes the plasticity and inherent ductility in the substrate to produce a multilayered product which has ductility substantially equal to he ductility of the substrate.
• the invention is particularly useful in brazing applications which require filling a gap of 100 ⁇ m or more.
• the multilayered brazing strip enhance the ability to braze certain dissimilar materials. For example.
• the prior art employed expensive silver-base brazing filler metal to braze the carbide to the steel.
• the thermal expansion coefficient of the carbides and steel are so different, internal stresses in the brazement are quite high and can lead to premature failure.
• a three-layered strip of a substrate, such as copper, sandwiched between rapidly solidified homogeneous-brazing alloy is used because the substrate accommodates the difference in stresses between the carbide and the steel while maintaining the service thermal and strength requirements of the tool.
• Another advantage to the production of thick brazing filler products is the elimination of the need for adhering together multiple strips of rapidly solidified material through the use of binders which could contaminate the brazement and/or create voids therein.
• the present invention one can, for the first time, produce brazing filler strips of rapidly solidified brazing foil in thickness of 100 ⁇ m or greater. Morever, because of the loss in ductility of rapidly solidified alloys as they approach 100 u m or more in thickness, the present invention provides thick brasing strip which has all the advantages associated with rapidly solidified brazing foil.
• the process of making the products of the present invention comprises the steps of arranging the foil in contact with the substrate and. thereafter, applying heat and pressure to the foil and substrate to cause the substrate to undergo plastic deformation and create metallic bonding between the foil and the substrate.
• the temperature of bonding must be at least about 0.4T, where T is the melting temperature of the alloy in degree Kelvin. K.
• the pressure applied to the layers must be sufficient to cause plastic deformation of the substrate in an amount necessary to create an essentially continuous, void-free interface between the f oil and the substrate . Accordingly, while the pressure will vary depending upon the substrate material employed, it is preferred that a force of at least about 0.75 MN be used. In particular, for roll bonding (500 mm O.D. rolls), we prefer to employ a separating force of between 0.75 MN and about 2.5 MN. although lower and higher pressures can be used.
• processes for brazing parts comprise the steps of arranging at least two parts relative to each other to define a gap therebetween, interposing in the gap a multilayered brazing filler material comprising a layer of rapidly solidified, homogeneous alloy foil metallically bonded to a substrate capable of undergoing substantial plastic deformation without substantial degradation of the ductility thereof, heating at least the filler material to melt at least the brazing foil layer of the strip and to cause the parts to be joined, and thus cooling the filler material to produce a brazement.
• Example 1 is provided in order to illustrate the scope of the inventions but are not intended to limit the scope of the invention to anything less than is disclosed hereinabove.
• Example 1 is provided in order to illustrate the scope of the inventions but are not intended to limit the scope of the invention to anything less than is disclosed hereinabove.
• a multilayered brazing strip was produced using an electrolytic tough-pitch copper substrate and a BAg-3 (American Welding Society Designation) microcrystalline alloy.
• BAg-3 microcrystalline alloy was produced by remelting Handy and Harman's Easy Flo-free TM alloy in a quartz crucible and casting by a planar flow rapid solidification technique.
• the center was 2 plies of 25 ram x 75 w m thick copper ribbon.
• the outer layers were made from 25 mm x 75 ⁇ m ribbon of BAg-3 brazing alloy.
• There BAg-3 layers had, prior to rolling, microhardness of 230 and 260 HV (Vickers microhardness units), respectively.
• the copper ribbon had a microhardness of 120 HV. In this case, the copper ribbon is about twice as ductile and malleable as the BAg-3 alloy.
• the strip was produced by high temperature consolidation on a Stanat 6" x 6" rolling mill. At 178 kN force, well bonded material was produced at rolls temperature of 380-400°C and at .03-.05 m/s rolling rate. By using two copper plies together as the substrate, a strip with the commercially desired thickness of 300 m was produced. Strips of 360 mm length were produced.
• Example 2
• Ribbon, 38 ⁇ m thick, of an alloy designated as MBF-2005 (having a composition within the range of compositions disclosed in U.S. 4,489,136) was bonded to both sides of a 406 u rn thick (16 gauge) copper strip.
• the consolidation was carried out in a Canadian Iron Foundry, 2-high, heated rolling mill with 500 mm diameter cast steel rolls.
• the 101 mm wide brazing alloy formed the outer layers while the 108 mm wide, soft copper composed the center core.
• Roll speed was held at 5 m/rain, roll temperature at 490°C. while rolling pressure was 2.0 MN.
• a well bonded multilayered strip was produced.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Laminated Bodies (AREA)

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• 1988
  • 1988-04-04 EP EP19880904044 patent/EP0357664A4/en not_active Withdrawn
  • 1988-04-04 WO PCT/US1988/001058 patent/WO1988007932A1/fr not_active Ceased
  • 1988-04-04 JP JP63503567A patent/JP2825249B2/ja not_active Expired - Lifetime

Patent Citations (1)

Non-Patent Citations (2)

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