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Abstract

A method of manufacturing an extruded, multi-hole-pipe (1) includes preparing an ingot having an aluminum alloy composition that contains one or more of Si: 2.0 mass % or less, Fe: 0.6 mass % or less, Cu: 0.6 mass % or less, Mn: 2.0 mass % or less, Mg: 0.4 mass % or less, Cr: 0.1 mass % or less, Zn: 1.5 mass % or less, Ti: 0.1 mass % or less, and B: 0.1 mass % or less. The total of the Si and Mn contents is 3.2 mass % or less, and the Si content is less than the Mn content. After performing a first homogenizing process at a temperature of 550° C. to 650° C. for 2 hours or more, a second homogenizing process is performed by holding the ingot at a temperature of 450° C. to 540° C. for 3 hours or more. Subsequently, the ingot is subjected to hot extrusion to form the multi-hole-pipe.

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First Claim