Aluminum alloy extruded product exhibiting excellent surface properties, method of manufacturing the same, heat exchanger multi-port tube, and method of manufacturing heat exchanger including the multi-port tube

Abstract

An aluminum alloy extruded product exhibiting excellent surface properties, contains 0.8 to 1.6% of Mn and 0.4 to 0.8% of Si at a ratio of Mn content to Si content (Mn % / Si %) of 0.7 to 2.4, with the balance being Al and inevitable impurities, the number of intermetallic compounds with a diameter (circle equivalent diameter) of 0.1 to 0.9 μm dispersed in a matrix being 2×105 or more per square millimeter. The aluminum alloy extruded product allows extrusion of a thin multi-port tube at a high limiting extrusion rate, prevents deposits from adhering to the surface of the extruded tube, and may be suitably used as a constituent member for an aluminum alloy automotive heat exchanger.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a divisional of prior U.S. application Ser. No. 11 / 489,941, filed Jul. 20, 2006.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an aluminum alloy extruded product exhibiting excellent surface properties, a method of manufacturing the same, a heat exchanger multi-port tube, and a method of manufacturing a heat exchanger including the multi-port tube.[0004]2. Description of Related Art[0005]As a constituent member for an automotive heat exchanger such as an evaporator and a condenser, an aluminum alloy which has a reduced weight and exhibits excellent thermal conductivity has been generally used. In the manufacture of automotive heat exchangers, an aluminum alloy tube (hereinafter called “tube”), such as an aluminum alloy extruded flat multi-port tube (hereinafter called “multi-port tube”) having a plurality of hollow portions divided by a plurality of partitions, is used a...

AI Technical Summary

Benefits of technology

The present invention provides an aluminum alloy extruded product with excellent surface properties, improved strength, and excellent extrudability. The alloy composition includes 0.8 to 1.6% of Mn and 0.4 to 0.8% of Si at a ratio of Mn content to Si content of 0.7 to 2.4. The extruded product exhibits high limiting extrusion rates, prevents deposits from adhering to the surface, and can be used as a constituent member for automotive heat exchangers. The invention also provides a method of manufacturing the aluminum alloy extruded product, a heat exchanger multi-port tube made of the alloy, and a method of manufacturing a heat exchanger including the multi-port tube.

Problems solved by technology

This reduces the activity of the flux, whereby brazeability deteriorates.

For example, when the extrusion ratio reaches several hundred to several thousand, such as when manufacturing a multi-port tube, the alloy exhibits significantly inferior extrudability in comparison with a pure Al material.

An alloy containing Mn and Si at high concentrations requires a ram pressure higher than that of a pure Al material, whereby the die tends to break or wear.

However, the extrudability is not necessarily sufficiently improved when extruding a tube such as a thin multi-port tube.

As a result, a brazing failure occurs in the portion which is not provided with the flux.

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