Aluminum alloy for heat exchanger fins

Abstract

An aluminum alloy fin stock material comprising about 0.9-1.4 wt. % Si, 0.3-0.6 wt. % Fe, 0.20-0.60 wt. % Cu, 1.0-1.7 wt. % Mn, 0.01-0.25 wt. % Mg, 0.01-3.0 wt. % Zn, up to 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. The aluminum alloy fin stock material is produced by a process including the steps of direct chill casting an ingot, hot rolling the ingot after the direct chill casting, cold rolling the aluminum alloy to an intermediate thickness, inter-annealing the aluminum alloy cold rolled to an intermediate thickness at a temperature between 200 and 400° C., and cold rolling the material after inter-annealing to achieve % cold work (% CW) of 20 to 40%. The aluminum alloy fin stock material possesses an improved combination of pre- and/or post-braze strength, thermal conductivity, sag resistance and/or corrosion potential.

We claim: 
     
         1 . An aluminum alloy, comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         2 . The aluminum alloy of  claim 1 , comprising about 0.95-1.35 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         3 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.35-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         4 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.40 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         5 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.40-0.55 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         6 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.1-1.65 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         7 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.05-0.2% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         8 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 1.5-2.75% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         9 . The aluminum alloy of  claim 1 , comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.05 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %. 
     
     
         10 . The aluminum alloy of  claim 1 , wherein the aluminum alloy has ultimate tensile strength of one or both of: at least 200 MPa, measured in pre-brazed condition, or at least 150 MPa, measured post-brazing. 
     
     
         11 . The aluminum alloy of  claim 1 , wherein the aluminum alloy has corrosion potential of −740 mV or less, measured post-brazing. 
     
     
         12 . The aluminum alloy of  claim 1 , wherein the aluminum alloy has thermal conductivity of greater than 40% IACS, measured post-brazing. 
     
     
         13 . A heat exchanger comprising the aluminum alloy of  claim 1 . 
     
     
         14 . A process for producing an aluminum alloy sheet, comprising:
 direct chill casting an aluminum alloy comprising about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %, into an ingot;   hot rolling the ingot after the direct chill casting;   after the hot rolling, cold rolling the aluminum alloy to an intermediate thickness;   after cold rolling, inter-annealing the aluminum alloy rolled to the intermediate thickness at 200-400° C.; and,   after inter-annealing, cold rolling the aluminum alloy to achieve % cold work (% CW) of 20 to 40%, resulting in the sheet having a thickness of 45-100 μm.   
     
     
         15 . The process of  claim 14 , wherein the inter-annealing is at a temperature from 250-360° C. 
     
     
         16 . The process of  claim 14 , wherein the inter-annealing is at a temperature from 290-360° C. 
     
     
         17 . The process of  claim 14 , wherein the inter-annealing time is 30 to 60 minutes. 
     
     
         18 . The process of  claim 14 , wherein % CW is from 30 to 40%. 
     
     
         19 . A process of making a heat exchanger comprising joining by brazing at least one first aluminum alloy form fabricated from an aluminum alloy with a second aluminum alloy form, comprising:
 assembling and securing the two or more aluminum forms together; and,   heating the two or more aluminum forms to a brazing temperature until joints are created among the two or more aluminum forms by capillary action,   wherein the first aluminum alloy comprises about 0.9-1.4 wt. % Si, about 0.3-0.6 wt. % Fe, about 0.20-0.60 wt. % Cu, about 1.0-1.7 wt. % Mn, about 0.01-0.25% Mg, about 0.1-3.0% Zn, up to about 0.10 wt. % Ti, with remainder Al and impurities at ≤0.15 wt. %.   
     
     
         20 . The process of  claim 19 , wherein the first aluminum alloy is capable of withstanding at least 20 days of CASS testing in accordance with ASTM B368 (2014) without detaching from the joint.