US20040118492A1 - High strength aluminium fin material for brazing - Google Patents

High strength aluminium fin material for brazing Download PDF

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Publication number
US20040118492A1
US20040118492A1 US10/683,455 US68345503A US2004118492A1 US 20040118492 A1 US20040118492 A1 US 20040118492A1 US 68345503 A US68345503 A US 68345503A US 2004118492 A1 US2004118492 A1 US 2004118492A1
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Prior art keywords
alloy
brazing
aluminium
strength
subjecting
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Abandoned
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US10/683,455
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English (en)
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Torkel Stenqvist
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Granges Sweden AB
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    • 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
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C22C21/08—Alloys based on aluminium with magnesium as the next major constituent with silicon
    • 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
    • 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
    • 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
    • C22F1/047—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 of alloys with magnesium as the next major constituent
    • 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
    • C22F1/05—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 of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions

Definitions

  • the present invention is related to an aluminium alloy intended as a fin-stock material for brazed products, such as heat exchangers, either as a braze clad material containing said alloy as a core or unclad.
  • the alloy is heat treatable (precipitation hardenable)
  • the material obtained has got a high strength after brazing, especially after an artificial ageing treatment, and gives a high corrosion resistance to the brazed product as it is sacrificial to the tube.
  • the material may be used to make products by any brazing method, in particular the controlled atmosphere brazing method (CAB) when a flux that allows alloys with Mg is used.
  • CAB controlled atmosphere brazing method
  • Mg may form small precipitates that increase the strength of the alloy considerably. This mechanism is called age hardening.
  • the AA6xxx series of alloys are based on the Mg and Si precipitates, but alloys in that series are generally not suitable for brazing, as most of them has a too high Mg content. Others are without Mn, reducing the sag resistance of the alloy.
  • Age hardening alloys have not yet been utilised in a fin stock material to be brazed in the CAB process.
  • a challenge today is to manufacture light-weight components for the automotive market.
  • a lot of research is therefore directed to reduce the weight of heat exchangers by using thinner strip.
  • the new invention shows a higher strength compared to the presently used alloys, while the corrosion protection of the tubes is retained. This will allow thinner fins with retained strength of the brazed product, thereby reducing the weight compared to products brazed today.
  • the higher strength can be utilised to give a more rigid brazed product that will withstand higher stresses, such as vibrations or pulsation of the internal pressure.
  • U.S. Pat. No. 6,120,848 discloses a method for providing the flux onto the surface of a brazing sheet, by mechanically embedding the flux in the cladding. It is mentioned that CsF fluxes allows a higher Mg in the core materials.
  • a modified flux containing caesium and/or lithium fluoride, and a modified braze cladding is used to braze the standard 1000, 3000, 5000 or 6000 alloys containing up to 3 wt-% Mg by CAB (Controlled Atmosphere Brazing).
  • the braze cladding on the tube surfaces contains, apart from the main alloying element silicon, lithium, magnesium, sodium, and optionally caesium.
  • a fin material with the following composition in wt.-%) is disclosed: 0.7-1.2 Si (0.75-1.0 preferred), up to 0.8 Fe (0.2-0.45 preferred), up to 0.5 Cu (0.2-0.4 preferred), 0.7-1.2 Mn (0.8-1.0 preferred), up to 0.35 Mg (0.2-0.35 preferred), up to 3 Zn, up to 0.25 Zr (0.05-0.15 preferred), up to 0.2 In (0.01-0.1 preferred), up to 1.5 Ni (0.3-1.2 preferred), up to 0.2 Ti, and up to 0.25 of Cr and V.
  • the object of the present invention is to provide a high strength, heat treatable, aluminium alloy while keeping the Mg content sufficiently low for brazing in a CAB furnace using a flux that tolerates Mg.
  • Another object is to provide a material with a sufficient corrosion sacrificial action to protect another material brazed to the invention.
  • Preferred applications are fins for heat exchangers, like automotive radiators, heaters, or charge-air coolers. Other applications are not excluded.
  • a quench sensitive alloy must be cooled rapidly after the solutionising treatment (i.e. the brazing operation) in order to keep the Mg and Si atoms in solid solution. A high Mn content will increase the quench sensitivity.
  • FIG. 1 shows the yield (Rp0.2) and the tensile strength (Rm) of the invented alloy compared to two reference materials after a braze simulation with cooling rates of 0.7° C./s and 2.5° C./s, natural ageing at room temperature.
  • FIG. 2 shows the tensile strength (Rm) of the invented alloy after a braze simulation with a cooling rate of 0.7° C./s and 2.5° C./s, artificial ageing at different temperatures.
  • FIG. 3 shows the yield strength (Rp0.2) of the invented alloy after a braze simulation with a cooling rate of 0.7° C./s and 2.5° C./s, artificial ageing at different temperatures.
  • FIG. 4 shows the sagging test jig.
  • the tensile strength of the standard material AA3003 is about 110 MPa and that of the state of the art FA6815 is about 135 MPa.
  • the yield strength of the standard material AA3003 is about 40 MPa and that of the state of the art FA6815 is about 50 MPa.
  • the alloy of the invention has a notably higher strength than the presently available alloys.
  • the concentration of silicon should be 0.5-1.0 wt-%, preferably 0.6-0.9 wt-%. Below 0.5 wt-% the ageing response is low, above 1.0 wt-% the solidus temperature of the alloy is significantly lowered.
  • Magnesium increases the strength by forming Mg 2 Si precipitates during ageing, but lowers the brazeability by reacting with the flux, even when the flux contains Cs or Li.
  • the Mg content could therefore be as low as 0.25 wt-% and as high as 0.6 wt-%. Below the lower limit the alloy would not give a sufficient number of the Mg 2 Si precipitates, and a high strength would not be obtained. The more Mg the higher the strength, but with a too high level the brazeability will be reduced, and furthermore there is a risk for incipient melting of the material at the brazing temperature.
  • the preferred Mg level will depend on both the used flux and the used tube material.
  • Zn is added, up to 4%. Zn will increase the sacrificial action of the fin material and the level must be optimised together with the tube material.
  • zirconium preferably 0.05-0.25 wt-% is added to the alloy.
  • Zr is distributed as small Al 3 Zr in the material. They will inhibit the recrystallisation, giving large grains of the material after brazing. Below 0.05 wt-% this effect is negligible, above 0.3 wt-% coarse precipitates are formed which will reduce the effect and the workability of the material.
  • Mn in solid solution increases the strength, however the quench sensitivity is also increased.
  • a low Mn content is beneficial to the strength if cooling rates are low.
  • Mn is beneficial to the sagging resistance and corrosion resistance.
  • the Mn content should be 0.3-0.7 wt-%, preferably 0.4-0.7 wt-%, most preferably 0.5-0.7 wt-%.
  • Fe has an adverse effect on the corrosion resistance and in higher amounts on the sagging resistance. It is therefore limited to 0.3 wt-%.
  • Copper is avoided in the alloy. Even though copper will further increase the strength, it has a negative influence on the corrosion behaviour. The electrochemical potential will increase, thereby reducing the anodic action and the protection of the tubes by the fin material.
  • Nickel is also avoided in the alloy. Nickel increases the risk for obtaining small grains in the product, and thereby reduce the sagging resistance.
  • the claimed material is produced by casting an aluminium alloy according to the invention, and thereafter subjecting the obtained material to a hot rolling and a cold rolling process. After said casting process the material may be scalped and clad with at least one additional layer. The material may be interannealed between two cold rolling passes, and partially or fully annealed after the final cold rolling step. The annealing step may also be omitted.
  • the 0.5 mm material was braze simulated with two different heating cycles, basically giving cooling rates of 2.5° C./s and 0.7° C./s between 400 and 200° C. This represents both an optimal cooling rate and one usually surpassed by brazing furnaces in practice.
  • FIG. 1 The increase in strength with time at room temperature is shown in FIG. 1. It is compared with the strength of the standard material AA3003 and the high strength fin material FA6815, the present state of the art. The increase in strength after natural ageing is substantial for the new material, even though the cooling rate after brazing is not optimal.
  • Example 2 Material from the same braze simulations as in Example 1 was artificially aged at different temperatures after a delay of one day. Three temperatures were used: 160, 180, and 195° C. The tensile strength of the samples is shown in FIG. 2 and the yield strength in FIG. 3. As can be seen, tensile strengths of 250 MPa and yield strengths surpassing 200 MPa may be obtained.
  • the material show a substantial age hardening response, and yield strengths more than three times as high as that of the standard materials in brazing of today were achieved.
  • the sagging resistance of the material was measured by mounting thin strip samples (gauge 0.1 mm) in a special jig, allowing 60 mm lever length (FIG. 4). The material in the jig was then subjected to a braze cycle with a 10 minute dwell at 600° C. The deflection is measured when the material has cooled off.
  • the mean deflection for the new invention was 27.6 mm, which may be compared to 17 to 23 mm for FA6815 and 35 to 40 mm for the standard heat treatable material AA6063.
  • the new invention shows a reasonable sagging resistance.

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  • Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Details Of Heat-Exchange And Heat-Transfer (AREA)
  • Laminated Bodies (AREA)
  • Details Of Measuring And Other Instruments (AREA)
  • Pressure Welding/Diffusion-Bonding (AREA)
US10/683,455 2002-10-14 2003-10-14 High strength aluminium fin material for brazing Abandoned US20040118492A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0203009A SE0203009D0 (sv) 2002-10-14 2002-10-14 High strenth aluminium fin material for brazing
SE0203009-6 2002-10-14

Publications (1)

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US20040118492A1 true US20040118492A1 (en) 2004-06-24

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Country Status (5)

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US (1) US20040118492A1 (fr)
EP (1) EP1435397B1 (fr)
AT (1) ATE304617T1 (fr)
DE (1) DE60301614T2 (fr)
SE (1) SE0203009D0 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060134451A1 (en) * 2003-09-26 2006-06-22 Susumu Saisho Aluminum brazin sheet
CN101408757B (zh) * 2007-10-11 2010-10-13 上海梅山钢铁股份有限公司 一种热轧生产管理级图形化轧线物料跟踪的方法
US9719156B2 (en) 2011-12-16 2017-08-01 Novelis Inc. Aluminum fin alloy and method of making the same
US10954325B2 (en) 2014-07-22 2021-03-23 University Of South Carolina Raft agents and their use in the development of polyvinylpyrrolidone grafted nanoparticles
US11933553B2 (en) 2014-08-06 2024-03-19 Novelis Inc. Aluminum alloy for heat exchanger fins

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2177638A1 (fr) 2008-10-15 2010-04-21 "Impexmetal" S.A. Alliage d'aluminium, en particulier pour la fabrication d'échangeurs thermiques
DE102008056819B3 (de) * 2008-11-11 2010-04-29 F.W. Brökelmann Aluminiumwerk GmbH & Co. KG Aluminiumlegierung und Verfahren zur Herstellung eines Produkts aus einer Aluminiumlegierung
EP3821048B1 (fr) * 2018-09-24 2024-07-24 Novelis Koblenz GmbH Matériau d'ailette de stock en alliage d'aluminium

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5771962A (en) * 1996-04-03 1998-06-30 Ford Motor Company Manufacture of heat exchanger assembly by cab brazing
US6120848A (en) * 1998-11-17 2000-09-19 Ford Motor Company Method of making a braze sheet
US6234243B1 (en) * 1999-12-14 2001-05-22 Visteon Global Technologies, Inc. Heat exchanger assembly with magnesium barrier
US6302973B1 (en) * 1997-08-04 2001-10-16 Corus Aluminium Walzprodukte Gmbh High strength Al-Mg-Zn-Si alloy for welded structures and brazing application
US6800244B2 (en) * 1999-11-17 2004-10-05 Corus L.P. Aluminum brazing alloy

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1335309A (en) * 1970-12-21 1973-10-24 Olin Corp Heat exchanger
AU663819B2 (en) * 1993-08-03 1995-10-19 Denso Corporation A1 alloy brazing material and brazing sheet for heat-exchangers and method for fabricating A1 alloy heat-exchangers
FR2713664B1 (fr) * 1993-11-17 1996-05-24 Pechiney Rhenalu Alliage type Al-Si-Mg à ductilité et emboutissabilité améliorées et procédé d'obtention.

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5771962A (en) * 1996-04-03 1998-06-30 Ford Motor Company Manufacture of heat exchanger assembly by cab brazing
US6302973B1 (en) * 1997-08-04 2001-10-16 Corus Aluminium Walzprodukte Gmbh High strength Al-Mg-Zn-Si alloy for welded structures and brazing application
US6120848A (en) * 1998-11-17 2000-09-19 Ford Motor Company Method of making a braze sheet
US6800244B2 (en) * 1999-11-17 2004-10-05 Corus L.P. Aluminum brazing alloy
US6234243B1 (en) * 1999-12-14 2001-05-22 Visteon Global Technologies, Inc. Heat exchanger assembly with magnesium barrier

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20060134451A1 (en) * 2003-09-26 2006-06-22 Susumu Saisho Aluminum brazin sheet
US8283049B2 (en) * 2003-09-26 2012-10-09 Kobe Steel, Ltd. Aluminum brazing sheet
CN101408757B (zh) * 2007-10-11 2010-10-13 上海梅山钢铁股份有限公司 一种热轧生产管理级图形化轧线物料跟踪的方法
US9719156B2 (en) 2011-12-16 2017-08-01 Novelis Inc. Aluminum fin alloy and method of making the same
US10954325B2 (en) 2014-07-22 2021-03-23 University Of South Carolina Raft agents and their use in the development of polyvinylpyrrolidone grafted nanoparticles
US11933553B2 (en) 2014-08-06 2024-03-19 Novelis Inc. Aluminum alloy for heat exchanger fins

Also Published As

Publication number Publication date
DE60301614D1 (de) 2005-10-20
SE0203009D0 (sv) 2002-10-14
EP1435397B1 (fr) 2005-09-14
EP1435397A1 (fr) 2004-07-07
DE60301614T2 (de) 2006-03-16
ATE304617T1 (de) 2005-09-15

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