Heat exchanger made of aluminum alloy and method of producing same

Abstract

A heat exchanger comprising a tube, a fin, and a header pipe, wherein the tube contains, in mass %, 0.15 to 0.45% of Mn, 0.20 to 0.50% of Si, and the balance of Al and unavoidable impurities, and is coated with a coating of brazing composition containing 1.0 to 5.0 g/m 2 of Si powder, 4.0 to 10.0 g/m 2 of KZnF 3 , and 0.5 to 3.0 g/m 2 of binder; the fin contains, in mass %, 1.20 to 1.80% of Zn, 0.70 to 1.20% of Si, 0.30 to 0.80% of Fe, 0.90 to 1.50% of Mn, one or two or more selected from 0.05 to 0.20% of Zr, 0.01 to 0.10% of V, and 0.01 to 0.10% of Cr, and the balance of Al and unavoidable impurities; and the header pipe comprises a core material, outer sacrificial corrosion protection material, and an inner brazing material.

1 . A heat exchanger made of an assembly including a tube, a fin, and a header pipe, wherein
 the tube is made of aluminum alloy having a composition containing, in mass 0.15 to 0.45% of Mn, 0.20 to 0.50% of Si, and the balance consisting of Al and unavoidable impurities; a coating of a brazing composition that is coated on a surface of the tube to which the fin is joined and contains 1.0 to 5.0 g/m of Si powder, 4.0 to 10.0 g/m 2  of Zn containing flux composed of KZnF 3 , and 0.5 to 3.0 g/m 2  of binder;   the fin is made of aluminum alloy containing, in mass %, 1.20 to 1.80% of Zn, 0.70 to 1.20% of Si, 0.30 to 0.80% of Fe, 0.90 to 1.50% of Mn, one or two or more elements selected from the group consisting of 0.05 to 0.20% of Zr, 0.01 to 0.10% of V, and 0.01 to 0.10% of Cr, and the balance consisting of Al and unavoidable impurities;   the header pipe comprises a core material, outer sacrificial corrosion protection material, and an inner brazing material; and   the fin is joined to the tube, and the tube is joined to the header pipe by brazing in the heat exchanger.   
   
   
       2 . A heat exchanger according to  claim 1 , wherein the tube has flat surfaces, and the coating of the brazing composition is formed on at least one flat surface of the tube such that side surfaces of the tube positioned on both sides of the flat surface are left not-coated with the brazing composition, and a perimeter b of the uncoated side surface satisfies b≦a×1.5, where a denotes a width of the side surface. 
   
   
       3 . A heat exchanger according to  claim 1 , wherein sacrificial layer of the header pipe contains 0.60 to 1.20% by mass of Zn, and the balance consisting of Al and unavoidable impurities. 
   
   
       4 . A heat exchanger according to  claim 2 , wherein the sacrificial corrosion protection material of the header pipe contains 0.60 to 1.20% by mass of Zn, and the balance consisting of Al and unavoidable impurities. 
   
   
       5 . A heat exchanger according to any one of  claims 1  to  4 , produced by a process comprising:
 constructing an assembly including a fin, a tube, and a header pipe by making the fin to contact the surface of the tube coated with the brazing composition, and making the tube to be assembled with the header pipe; and   heating the assembly to a predetermined brazing temperature, wherein the assembly is held at an intermediate temperature range from 530 to 575° C. for 4 to 8 minutes during the heating, and is subsequently heated to the predetermined brazing temperature.   
   
   
       6 . A heat exchanger according to  claim 5 , wherein the predetermined brazing temperature is in the range from 580 to 615° C.