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
  • B23K35/22—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
  • B23K35/28—Selection of soldering or welding materials proper with the principal constituent melting at less than 950 degrees C
  • B23K35/286—Al as the principal constituent
• • 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
  • B23K1/00—Soldering, e.g. brazing, or unsoldering
  • B23K1/0008—Soldering, e.g. brazing, or unsoldering specially adapted for particular articles or work
  • B23K1/0012—Brazing heat exchangers
• • 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
  • B23K35/001—Interlayers, transition pieces for metallurgical bonding of workpieces
  • B23K35/002—Interlayers, transition pieces for metallurgical bonding of workpieces at least one of the workpieces being of light metal
• • 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, brazing
  • B23K35/0233—Sheets, foils
  • B23K35/0238—Sheets, 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
  • B23K35/28—Selection of soldering or welding materials proper with the principal constituent melting at less than 950 degrees C
  • B23K35/286—Al as the principal constituent
  • B23K35/288—Al as the principal constituent with Sn or Zn
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/016—Layered products comprising a layer of metal all layers being exclusively metallic all layers being formed of aluminium or aluminium alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
  • C22C21/04—Modified aluminium-silicon alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
• • 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
  • B23K2103/00—Materials to be soldered, welded or cut
  • B23K2103/08—Non-ferrous metals or alloys
  • B23K2103/10—Aluminium or alloys thereof

Definitions

• the invention relates to bands used in the field of heat exchangers (generally of thickness from 0.05 to 3 mm, preferably 0.15 to 2.5 mm) made of an aluminum-manganese core alloy (series 3000 according to the Aluminum Association nomenclature), possibly plated on one or both sides with a cover alloy, most often an aluminum-silicon brazing alloy (4000 series according to the Aluminum Association nomenclature) and / or an intermediate alloy, placed between the core and the possible brazing alloy, in aluminum-manganese alloy (3000 series according to the Aluminum Association nomenclature).
• These bands are intended in particular for the manufacture of elements, such as tubes, collectors and plates, of heat exchangers assembled by brazing.
• the properties required for the aluminum alloy strips used for the manufacture of brazed exchangers are in particular good brazability, high mechanical strength after brazing, so as to use thicknesses as low as possible, formability sufficient for easy shaping of tubes, manifold fins and plates, before brazing, and good corrosion resistance.
• the alloy chosen is easy to cast and roll, and that the cost of manufacturing the strips is compatible with the requirements of the automotive industry.
• An alloy used is 3003 with the composition (% by weight according to standard EN 573-3):
• Patent EP 0326337 (Alcan International) describes a plated strip whose base alloy has the composition:
• the low Si content preferably ⁇ 0.05%, allows the formation of a dense layer of Mn precipitates, which can act as a barrier to the diffusion of the silicon of the coating alloy, and increases the strength. corrosion.
• WO 94/22633 is a variant of the previous one which differs only by a higher Cu content (0.6 - 0.9%).
• US Patent 5,350,436 (Kobe Alcoa and Nippondenso) describes a base alloy of composition: Si: 0.3 - 1.3 Cu ⁇ 0.2 Mn: 0.3 - 1.5 Mg ⁇ 0.2 Ti: 0, 02 - 0.3 Fe not mentioned.
• Patent EP 0718072 (Hoogovens Aluminum Walz area) describes a base alloy of composition: Si> 0.15 Fe ⁇ 0.8 Cu: 0.2 - 2 Mn: 0.7 - 1.5 Mg: 0.1 - 0 , 6 with
• a first category of alloys has a very low Si content ( ⁇ 0.15 and preferably ⁇ 0.05 %) with or without a low Fe content, but, in all cases, less demanding than for Si. These very low Si contents ( ⁇ 0.05%) can only be obtained starting from bases pure, which increases manufacturing costs.
• a second category of alloys by questioning the need for a very low Si content to obtain good corrosion resistance, on the contrary has a rather high Si content (0.5 to 0.8%), possibly to compensate for the loss of mechanical strength associated with low contents of hardening elements Mg and Cu.
• the Applicant has determined a range of composition making it possible to improve the mechanical strength without degrading the corrosion resistance or the solderability.
• the subject of the invention is thus a strip, intended for the manufacture of brazed heat exchangers, having an aluminum alloy core of composition (% by mass):
• Si 0.10 - 0.30%, preferably 0.15 - 0.25%
• Mg 0.1 - 0.3%, preferably 0.1 - 0.21%
• the subject of the invention is also a method of manufacturing a strip, comprising the successive steps of:
• the thickness of the strip after cold rolling preferably being 0.15 to 3 mm and
• the subject of the invention is also a method for manufacturing a strip according to the present invention, comprising the successive steps of:
• the thickness of the strip after cold rolling preferably being 0.15 to 3 mm and
• the subject of the invention is also a heat exchanger produced at least in part from a strip according to the present invention.
• a subject of the invention is also the use of a strip according to the present invention, for the manufacture of a heat exchanger, said strip having improved mechanical strength without degradation of corrosion resistance or solderability.
• FIG. 1 Figure 1 is a photograph of a sample prepared with edge protection with silicone gasket prior to SWAAT corrosion testing.
• Figure 2 shows a diagram of the cutting plane of a sample after corrosion test and after falling of the silicone seals. This is a top view of a tested sample.
• FIG. 3 represents a diagram of the principle of characterization of corrosion according to the example. This is a side view in section along the width L of the sample of FIG. 2. Reference 1 corresponds to the face exposed to corrosion attack. Reference 2 corresponds to the measurement zones of the maximum depth of corrosions by fields in optical micrography.
• FIG. 4 shows the corrosion depth distribution after four weeks of exposure (SWAAT test) for the samples in the example.
• the mark A corresponds to the sample having a core alloy A (prior art).
• the mark B corresponds to the sample having a core alloy B (according to the invention).
• the abscissa axis corresponds to the corrosion depth in pm.
• the y-axis corresponds to the distribution function.
• FIG. 5 shows the sectional micrographs of the bands after SWAAT testing for the samples of the example, after four weeks of exposure.
• the mark A corresponds to the sample having a core alloy A (prior art).
• the mark B corresponds to the sample having a core alloy B (according to the invention).
• the strip according to the present invention comprises an aluminum alloy core of composition (% by mass):
• Si 0.10 - 0.30%, preferably 0.15 - 0.25%
• Mg 0.1 - 0.3%, preferably 0.1 - 0.21%
• composition limits of the base alloy can be justified as follows.
• a minimum silicon content of 0.10% makes it possible to avoid using a pure base, the cost of which is high.
• silicon contributes to the mechanical strength by forming Mg2Si precipitates. Beyond 0.30%, silicon can have an unfavorable influence on the corrosion resistance, because of the formation of manganese dispersoids AIMnSi and AIMnFeSi.
• An iron content limited to less than 0.25% is also favorable to corrosion resistance and formability, but it is not necessary to go down to very low contents ⁇ 0.15% which would lead to prices high cost.
• Copper is a hardening element which contributes to the mechanical resistance, but, above 1.1%, coarse intermetallic compounds are formed on casting which adversely affect the homogeneity of the metal and constitute sites of initiation of corrosion. In addition, above 1.1%, the castability of the alloy deteriorates and the solidus of the core alloy becomes too weak, making the brazing temperature range too low.
• the manganese is within limits close to those of the alloy 3003; it contributes to mechanical strength and corrosion resistance.
• the flowability of the alloy is reduced beyond 1.4% Mn.
• Magnesium has a favorable effect on mechanical strength. On the other hand, it is detrimental to solderability, insofar as it migrates to the surface of the plating and forms an MgO oxide, or even reduces the efficiency of the flux. For this reason, its content should be limited to 0.3%. For very demanding applications it may be necessary to completely remove the magnesium.
• a limited addition of zinc can have a beneficial effect on corrosion resistance, by modifying the electrochemical mechanisms, especially for the alloys with the highest copper content. However, it must remain below 0.2% to avoid too high a susceptibility to generalized corrosion.
• the strips according to the present invention have a thickness generally comprised from 0.05 to 3 mm, preferably from 0.1 to 1.8 mm, depending on the type of part manufactured, and can be plated with a cover alloy, which can be either a brazing alloy or an alloy acting as the sacrificial anode to protect the part from corrosion such as a zinc alloy such as alloy 7072.
• a cover alloy which can be either a brazing alloy or an alloy acting as the sacrificial anode to protect the part from corrosion such as a zinc alloy such as alloy 7072.
• the brazing alloy is of the 4xxx family of alloys with a liquidus temperature sufficiently low compared to the solidus of the core alloy to have a sufficient temperature range for brazing, acceptable mechanical strength and good wettability.
• These alloys can contain addition elements, for example strontium.
• the strip according to the present invention is plated on one or both sides of a brazing aluminum alloy, preferably a 4xxx alloy comprising from 4 to 13%, preferably from 6 to 11% by mass of Si and up to 0.5%, preferably up to 0.3% by mass of Fe.
• a brazing aluminum alloy preferably a 4xxx alloy comprising from 4 to 13%, preferably from 6 to 11% by mass of Si and up to 0.5%, preferably up to 0.3% by mass of Fe.
• the brazing aluminum alloy comprises (% by mass):
• Cu up to 0.4%, preferably up to 0.1%
• Mn up to 0.2%, preferably up to 0.1%
• Mg up to 0.3%, preferably up to 0.1%
• Zn up to 0.2%, preferably up to 0.1%
• composition AA4045 is an aluminum alloy which may be suitable as a brazing alloy according to the present invention. Its composition is, in% by mass: from 9 to 11% of Si, up to 0.8% of Fe, up to 0.30% of Cu, up to 0.05% of Mn, up to 0.05% Mg, up to 0.10% Zn, up to 0.20% Ti, other elements less than 0.05% each and less than 0.15% in total, the remainder being aluminum.
• the preceding composition preferably comprises up to 0.6% Fe.
• the preceding composition preferably comprises up to 0.1% Cu.
• composition AA4343 is an aluminum alloy which may be suitable as a brazing alloy according to the present invention. Its composition is, in% by mass: from 6.8 to 8.2% of Si, up to 0.8% of Fe, up to 0.25% of Cu, up to 0.10% of Mn , up to 0.05% Mg, other elements less than 0.05% each and less than 0.15% in total, the remainder being aluminum.
• the preceding composition preferably comprises up to 0.3% Fe.
• the preceding composition preferably comprises up to 0.1% Cu.
• the brazing alloy according to the present invention does not include Mg.
• an aluminum alloy with a sacrificial anode effect in particular an alloy containing zinc, such as alloy 7072.
• the strip according to the present invention is plated on one or two faces of a so-called interlayer aluminum alloy, placed between the core and the possible brazing alloy, preferably comprising (in% by mass):
• Si up to 0.5%, more preferably up to 0.2%;
• Fe up to 0.7%, more preferably up to 0.3%, even more preferably up to 0.2%;
• Mn from 0.3 to 1.4%, more preferably from 0.6 to 0.8%, according to a variant from 1 to 1.3%;
• the intermediate aluminum alloy of the strip according to the present invention comprises (% by mass): Si ⁇ 0.15%; Fe ⁇ 0.2%; Cu ⁇ 0.1%; Mn from 0.6 to 0.8%; Mg ⁇ 0.02%; other elements ⁇ 0.05% and ⁇ 0.15% in total, remainder of aluminum.
• the intermediate aluminum alloy is an AA3xxx series alloy.
• the strip according to the present invention has a maximum tensile strength Rm (measured according to the ISO 6892-1 standard after brazing) greater than 180 MPa, more preferably greater than 190 MPa, even more preferably greater than 195 MPa.
• Rm measured according to the ISO 6892-1 standard after brazing
• the strip according to the present invention is a so-called brazing strip, which can be used for the manufacture of different parts of a heat exchanger, for example tubes, plates, collectors, etc.
• the strip according to the present invention makes it possible to improve the fatigue behavior.
• the absence of homogenization of the core seems to make it possible to further improve the fatigue behavior.
• the subject of the invention is also a method of manufacturing a strip, comprising the successive steps of:
• the thickness of the strip after cold rolling preferably being 0.15 to 3 mm and
• the subject of the invention is also a method for manufacturing a strip according to the present invention, comprising the successive steps of:
• the thickness of the strip after cold rolling preferably being 0.15 to 3 mm and
• the strip can be used in the annealed state (O state) by carrying out a final annealing at a temperature between 320 and 380 ° C, in a continuous furnace or in batch oven.
• This annealing leads to the recrystallization of the alloy and improves the formability.
• it is used in the hardened state, which leads to better mechanical resistance, for example an H14 or H24 state (according to standard NF EN 515), the latter state being obtained by a restoration annealing between 250 and 300 ° C, avoiding recrystallization
• the core alloy plate Prior to installing the plating material, the core alloy plate can be homogenized at a temperature of 580 to 630 ° C. This homogenization is favorable to the ductility of the rolled strip and it is recommended when the strip is used in the O state. It promotes the coalescence of the dispersoids with Mn.
• the subject of the invention is also a heat exchanger produced at least in part from a strip according to the present invention.
• a subject of the invention is also the use of a strip according to the present invention, for the manufacture of a heat exchanger, said strip having improved mechanical strength without degradation of corrosion resistance or solderability.
• the tapes according to the present invention can be used in the manufacture of radiators, in particular of automobiles, such as engine cooling radiators, oil radiators, heating radiators and charge air coolers, as well as in air conditioning systems.
• Alloy A is a core alloy according to the prior art.
• Alloy B is a core alloy according to the present invention.
• Alloy C is AA4343 brazing alloy.
• Alloy D is an alloy used as an intermediate alloy.
• brazing alloy alloy C - 7.5% of total thickness
• interlayer alloy alloy D - 10% of total thickness
• core alloy alloy A or B - 75% of total thickness
• brazing alloy alloy C - 7.5% of total thickness
• the sandwiches were preheated to 500 ° C. for 1 to 8 hours and hot rolled at this temperature to a total thickness of 3.5 mm. Then the sandwiches were cold rolled without intermediate annealing to a final total thickness of 480 ⁇ m. Finally, the bands obtained were subjected to annealing to obtain a metallurgical state 0, at 360 ° C for 1 hour for the bands having a homogenized core, and at 430 ° C for 1 hour for the bands having a non-homogenized core. .
• the bands having a core according to the present invention exhibited a significant increase in mechanical properties, with or without homogenization.
• the bands having a core according to the present invention have exhibited an elongation of the same order of magnitude as the bands having a core according to the prior art. Elongation was improved with homogenization of the core for the two core alloys tested. Before brazing, elongation is the main criterion to ensure sufficient ductility for stamping. The elongation was of the same order of magnitude for the two souls tested. Elongation was improved with homogenization of the core for the two core alloys tested.
• homogenization of the core seems preferable because it seems to allow better elongation.
• homogenization of the core makes it possible to reduce the sensitivity to dissolution during the brazing by comparing with a non-homogenized core.
• the corrosion resistance was determined on samples like those presented above, with a homogenized core, but on the face without an intermediate alloy.
• the SWAAT test saliva water acetic acid test according to the ASTM G85 A3 standard was used for 4 weeks.
• Samples of dimension 45 mm (L) x 65 mm (TL) x 0.22 mm (TC) were taken from each sheet (see Figure 1).
• the samples were degreased with acetone.
• the tested area measured approximately 40mm (L) x 60mm (TL) given about 5mm edge protection.
• the area exposed to the corrosion test was approximately 2400 mm 2 ⁇ 100.
• the SWAAT test is a cyclic test composed of a fog phase of 30 min and a wet phase of 1h30. It takes place at a temperature of 49 ° C. After 4 weeks of SWAAT testing, samples were rinsed with hot water and etched for 10 min with 70% nitric acid. At the end of this stripping, sectional micrographs (direction L x TC) were taken: 4 strips of 40 mm (L) x 10 mm (TL) x 0.22 mm (TC) were cut as indicated in the Figure 2.
• Figure 4 shows the corrosion depth distribution for the two samples tested.
• Figure 5 shows a micrograph of samples tested after 4 weeks of SWAAT testing.
• Figures 4 and 5 show that the sample having a core according to the present invention (B) exhibited better corrosion resistance compared to the sample having a core according to the prior art (A).

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Details Of Heat-Exchange And Heat-Transfer (AREA)
• Laminated Bodies (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)

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• 2020
  • 2020-02-27 WO PCT/FR2020/050390 patent/WO2020178508A1/fr unknown
  • 2020-02-27 US US17/436,040 patent/US20220002843A1/en active Pending
  • 2020-02-27 EP EP20719683.3A patent/EP3934840A1/de active Pending
  • 2020-02-27 DE DE20719683.3T patent/DE20719683T1/de active Pending

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