High-conductivity finstock alloy, method of manufacture and resultant product

Abstract

A high-conductivity finstock alloy is for brazed aluminum heat exchangers. The finstock comprises an aluminum alloy comprised of between about 0.7-1.2% Si, about 1.9-2.4% Fe, about 0.6-1.0% Mn, up to about 0.5% Mg, up to about 2.5% Zn, up to about 0.10% Ti, and up to about 0.05% In, with the remainder comprising Al and tolerable impurities. A method of manufacturing finstock from the foregoing aluminum alloy comprises continuously casting the alloy as a strip with a thickness of about 2-10 mm at an average cooling rate above about 300° C./sec. and then multiple pass cold rolling the strip using one or more intermediate partial anneals at a temperature of about 300-450° C. A fin made from the foregoing finstock is also disclosed. A brazed aluminum heat exchanger having cooling fins made from the foregoing finstock is also disclosed.

1 . A finstock comprising: 
 an aluminum alloy comprised of about 0.7-1.2% Si, about 1.9-2.4% Fe, about 0.6-1.0% Mn, up to about 0.5% Mg, up to about 2.5% Zn, up to about 0.10% Ti, and up to about 0.05% In, with the remainder comprising Al and tolerable impurities.    
   
   
       2 . The finstock of  claim 1  wherein said tolerable impurities comprise at least one of the following: 
 up to about 0.2% Cu, up to about 0.2% Zr, up to about 0.05% Cr and up to about 0.3% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.4%.    
   
   
       3 . The finstock of  claim 2  wherein said tolerable impurities are comprised of up to about 0.05% Cu, up to about 0.05% Zr, up to about 0.05% Cr and up to about 0.05% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.10%.  
   
   
       4 . The finstock of  claim 2  wherein said aluminum alloy is comprised of about 0.8-1.1% Si, about 2.0-2.2% Fe, about 0.6-0.8% Mn, up to about 1.5% Zn, up to about 0.2% Mg, up to about 0.05% Ti, and up to about 0.03% In.  
   
   
       5 . The finstock of  claim 4  wherein said tolerable impurities are comprised of up to about 0.05% Cu, up to about 0.05% Zr, up to about 0.05% Cr and up to about 0.05% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.10%.  
   
   
       6 . The finstock of  claim 1  including a post-braze electrical conductivity of greater than about 48% IACS.  
   
   
       7 . The finstock of  claim 6  wherein said post-braze electrical conductivity is greater than about 50% IACS.  
   
   
       8 . The finstock of  claim 6  including a post-braze Ultimate Tensile Strength of greater than about 120 MPa.  
   
   
       9 . The finstock of  claim 8  wherein said post-braze ultimate tensile strength is greater than about 130 MPa.  
   
   
       10 . A fin for a heat exchanger, comprising: 
 an aluminum alloy finstock comprised of about 0.7-1.2% Si, about 1.9-2.4% Fe, about 0.6-1.0% Mn, up to about 0.5% Mg, up to about 2.5% Zn, up to about 0.10% Ti, and up to about 0.05% In, with the remainder comprising Al and tolerable impurities.    
   
   
       11 . The fin of  claim 10  wherein said tolerable impurities comprise at least one of the following: 
 up to about 0.2% Cu, up to about 0.2% Zr, up to about 0.05% Cr and up to about 0.3% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.4%.    
   
   
       12 . The fin of  claim 11  wherein said tolerable impurities are comprised of up to about 0.05% Cu, up to about 0.05% Zr, up to about 0.05% Cr and up to about 0.05% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.10%.  
   
   
       13 . The fin of  claim 11  wherein said aluminum alloy is comprised of about 0.8-1.1% Si, about 2.0-2.2% Fe, about 0.6-0.8% Mn, up to about 1.5% Zn, up to about 0.2% Mg, up to about 0.05% Ti, and up to about 0.03% In.  
   
   
       14 . A brazed aluminum heat exchanger comprising: 
 at least one tank structured to hold a coolant;    a header plate coupled to said at least one tank, said header plate including a plurality of apertures;    a plurality of substantially parallel fluid-carrying tubes each extending substantially perpendicular from one of said plurality of apertures in said header plate and structured to receive said coolant therethrough; and    a plurality of fins disposed between said plurality of fluid-carrying tubes, said fins being in thermal communication with said plurality of fluid-carrying tubes and structured to transfer heat away therefrom, in order to cool said coolant as it circulates therein, said plurality of fins comprising:    an aluminum alloy finstock comprised of about 0.7-1.2% Si, about 1.9-2.4% Fe, about 0.6-1.0% Mn, up to about 0.5% Mg, up to about 2.5% Zn, up to about 0.10% Ti, and up to about 0.05% In, with the remainder comprising Al and tolerable impurities.    
   
   
       15 . The heat exchanger of  claim 14  wherein said tolerable impurities comprise at least one of the following: 
 up to about 0.2% Cu, up to about 0.2% Zr, up to about 0.05% Cr and up to about 0.3% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.4%.    
   
   
       16 . The heat exchanger of  claim 15  wherein said tolerable impurities are comprised of up to about 0.05% Cu, up to about 0.05% Zr, up to about 0.05% Cr and up to about 0.05% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.10%.  
   
   
       17 . The heat exchanger of  claim 15  wherein said aluminum alloy is comprised of about 0.8-1.1% Si, about 2.0-2.2% Fe, about 0.6-0.8% Mn, up to about 1.5% Zn, up to about 0.2% Mg, up to about 0.05% Ti, and up to about 0.03% In.  
   
   
       18 . A method of manufacturing aluminum alloy finstock from an alloy comprised of about 0.7-1.2% Si, about 1.9-2.4% Fe, about 0.6-1.0% Mn, up to about 0.5% Mg, up to about 2.5% Zn, up to about 0.10% Ti, up to about 0.05% In optionally, with the remainder comprising Al and tolerable impurities, the method comprising the steps of: 
 providing a metal transfer system and a caster, said caster having a caster tip for strip casting said alloy;    casting said alloy as a strip with a thickness of between about 2-10 mm by controlled continuous strip casting with an average cooling rate above about 300° C./sec. while substantially avoiding temperatures in said metal transfer system that would permit intermetallics to nucleate prior to exiting said caster tip and while substantially eliminating the formation of coarse eutectic center-line segregation;    cold rolling said strip in at least one pass to a first intermediate annealing gauge of about 1-4 mm;    applying a first intermediate anneal to said strip for about 1-10 hours at a temperature of about 300-450° C.;    cold rolling said strip to a final intermediate anneal gauge of about 0.05-0.2 mm;    applying a final intermediate anneal to said strip for about 1-10 hours at a temperature of about 300-450° C.; and    cold rolling said strip to a final gauge using a reduction of about 15-50%.    
   
   
       19 . The method of  claim 18  further including the step of applying a partial anneal of said final gauge, said partial anneal being for about 1-12 hours at a temperature of about 150-240° C.  
   
   
       20 . The method of  claim 18  further including the step of at least one additional intermediate anneal after at least about 70% cold reduction following said step of applying said first intermediate anneal and before said step of cold rolling said strip to said final intermediate anneal gauge, said at least one additional intermediate anneal being applied for between about 1-10 hours at a temperature of about 300-450° C.  
   
   
       21 . The method of  claim 20  further including the steps of applying said at least one additional intermediate anneal for about 1-6 hours at a temperature of about 330-400° C.  
   
   
       22 . The method of  claim 21  wherein said gauge of said strip at said additional intermediate anneal is sufficient to allow a subsequent cold reduction of at least 70% to said final intermediate gauge.  
   
   
       23 . The method of  claim 18  wherein the thickness of said strip cast by said step of casting said alloy as a strip, is about 5-9 mm.  
   
   
       24 . The method of  claim 18  wherein said steps of applying a first intermediate anneal and applying a second intermediate anneal are performed for about 1-6 hours at a temperature of between about 330-400° C.  
   
   
       25 . The method of  claim 18  wherein said step of cold rolling said strip to a final gauge, uses a reduction of about 15-35%.  
   
   
       26 . The method of  claim 18  wherein said tolerable impurities within said finstock alloy comprise at least one of the following: 
 up to about 0.2% Cu, up to about 0.2% Zr, up to about 0.05% Cr and up to about 0.3% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0.4%.    
   
   
       27 . The method of  claim 26  wherein said finstock is manufactured from an alloy which comprises about 0.8-1.1% Si, about 2.0-2.2% Fe, about 0.6-0.8% Mn, up to about 1.5% Zn, up to about 0.2% Mg, up to about 0.05% Ti, and up to about 0.03% In, with the remainder comprising Al and said tolerable impurities.  
   
   
       28 . The method of  claim 27  wherein said tolerable impurities are comprised of up to about 0.05% Cu, up to about 0.05% Zr, up to about 0.05% Cr and up to about 0.05% Ni, with the aggregate of all of said tolerable impurities not to exceed about 0. 10%.