Aluminum alloy fin material for heat exchanger use excellent in buckling resistance and method for manufacturing same

Abstract

An aluminum alloy fin material for heat exchanger use excellent in buckling resistance which, even if the fin material is reduced to a final sheet thickness of 30 to 80 μm, is excellent in formability at the time of corrugation, has a suitable strength before brazing enabling easy fin formation, exhibits a suitable self corrosion resistance and sacrificial anode effect, and is high in strength as a material for forming working fluid passages is provided. By mass %, Si: 1.3% to 1.6%, Fe: 0.30% to 0.70%, Mn: 1.8% to 2.3%, Zn: 0.5% to 2.0%, and Ti: 0.002% to 0.10% are contained, as impurities, Mg is limited to 0.05% or less and Cu is limited to 0.06% or less, and the balance is unavoidable impurities and Al, a final sheet thickness is 30 to 80 μm, a tensile strength is 260 MPa or less, a solidus temperature is 615° C. or more, and further a tensile strength when measured after brazing heating then cooling, is 170 MPa or more and a spontaneous potential is −780 mV to −700 mV.

1 . An aluminum alloy fin material for heat exchanger use excellent in buckling resistance containing, by mass %, Si: 1.3% to 1.6%, Fe: 0.30% to 0.70%, Mn: 1.8% to 2.3%, Zn: 0.5% to 2.0%, and Ti: 0.002% to 0.10%, further limiting, as impurities, Mg to 0.05% or less and Cu to 0.06% or less, and having a balance of unavoidable impurities and Al, where
 a final sheet thickness is 30 to 80 μm, a tensile strength is 260 MPa or less, a solidus temperature is 615° C. or more, and further a tensile strength when measured after brazing heating then cooling, is 170 MPa or more and a spontaneous potential is −780 mV to −700 mV.   
     
     
         2 . A method for manufacturing an aluminum alloy fin material for heat exchanger use excellent in buckling resistance comprising
 a continuous casting step of pouring a melt of the above composition described in  claim 1  and using a twin-belt casting machine to continuously cast then take up in a coil a thickness 6 to 15 mm slab,   a primary cold rolling step of cold rolling to a sheet thickness of 1.0 to 6.0 mm,   a primary process annealing step of process annealing at 360 to 460° C.,   a secondary cold rolling step of cold rolling to a sheet thickness of 0.05 to 0.12 mm,   a secondary process annealing step of process annealing at 200 to 350° C., and   a final cold rolling step of cold rolling by a cold rolling rate of 20 to 50% to a final sheet thickness of 30 to 80 μm.