Aluminum alloy fin material, its manufacturing method and heat exchanger having the material

Abstract

An aluminum alloy fin material for a heat exchanger, which is composed of an aluminum alloy produced by a semi-continuous casting method with the following composition: Mn: 1.2-2.0%, Cu: 0.05-0.20%, Si: 0.5- 1.30%, Fe: 0.05-0.5%, Zn: 1.0-3.0%, the remainder is composed of Al and unavoidable impurities, and Ti: 0.01-0.20% in mass%, Cr: 0.01-0.20%, Mg: one or more of 0.01 to 0.20%, the tensile strength of aluminum alloy fin material for heat exchangers after brazing and heating is above 140Mpa, the yield strength is above 50Mpa, and the electrical conductivity is above 42% IACS. The average crystal grain size is not less than 150 μm and less than 700 μm, and the potential is not less than -800 mV and not more than -720 mV.

Description

technical field [0001] The present invention relates to an aluminum alloy fin material for heat exchangers excellent in strength, conductivity, and brazability for use in heat exchangers for automobiles, a method for manufacturing the aluminum alloy fin material for heat exchangers, and an aluminum alloy fin material for heat exchangers equipped with the same Fin material for heat exchangers. Background technique [0002] It is required that fin materials for automotive heat exchangers have high strength, high electrical conductivity, and brazing properties after brazing. However, since there is a trade-off relationship among these characteristics, it has been difficult to satisfy all the characteristics so far. In the past, for example, in Japanese Patent Laid-Open No. 2008-038166 or Japanese Patent Laid-Open No. 2001-335901, fin materials excellent in strength and conductivity after brazing have been proposed. The fin material proposed in Japanese Patent Laid-Open No. 20...

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Problems solved by technology

[0003] On the other hand, for example, fin materials using the semi-continuous casting method (DC method) in which the cooling rate of the slab during casting is 10° C. / sec or less cannot obtain fine crystalline products at the time of casting, and the crystalline products The size is easy to coarsen to more than 1μm

In this case, since the coarse crystalline products present in the material become nucleation sites for recrystallization during brazing, the crystal grains tend to be finer, and it is easy to cause welding corrosion starting from the grain boundaries, which is not conducive to brazability.

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