Extruded, multi-hole-pipe manufacturing method

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.

1 . An extruded, multi-hole-pipe manufacturing method, comprising:
 preparing an ingot having an aluminum alloy composition that contains one or two or more elements selected from the group consisting of Si: 2.00 mass % or less, Fe: 0.60 mass % or less, Cu: 0.60 mass % or less, Mn: 2.00 mass % or less, Mg: 0.40 mass % or less, Cr: 0.10 mass % or less, Zn: 1.50 mass % or less, Ti: 0.10 mass % or less, and B: 0.10 mass % or less, wherein the total of the Si content and the Mn content is 3.20 mass % or less, and the Si content is less than the Mn content;   performing a first homogenizing process by holding the ingot at a first hold temperature of 550° C. or higher and 650° C. or lower for 2 h or more;   subsequently performing a second homogenizing process by holding the ingot at a second hold temperature of 450° C. or higher and 540° C. or lower for 3 h or more; and   subsequently preparing an extruded, multi-hole pipe by performing hot extrusion on the ingot.   
     
     
         2 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein, after the first homogenizing process has completed, the ingot is cooled at an average cooling rate of 20° C./h or more and 60° C./h or less to the second hold temperature of the second homogenizing process. 
     
     
         3 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein, after the first homogenizing process has completed, the ingot is cooled to a temperature that is lower than the second temperature of the second homogenizing process, and subsequently the ingot is heated at an average temperature-rise rate of 20° C./h or more and 60° C./h or less to the second hold temperature of the second homogenizing process. 
     
     
         4 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein, when preparing the ingot, an aluminum scrap material is used as at least a portion of the casting material. 
     
     
         5 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the extruded, multi-hole pipe is prepared by the hot extrusion such that the extruded, multi-hole pipe has a flat, cross-sectional shape and has a width-to-thickness ratio of 2 or more and 50 or less. 
     
     
         6 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the extruded, multi-hole pipe is prepared by the hot extrusion such that the extruded, multi-hole pipe has an outer-wall portion that partitions an exterior space from an interior space of the extruded, multi-hole pipe and has a plurality of partition portions that partitions the outer-wall portion and the interior space, the thickness of the outer-wall portion and the partition portions being 0.10 mm or more and 2.0 mm or less. 
     
     
         7 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition consists of one or more elements selected from the group consisting of Si: 2.00 mass % or less, Fe: 0.60 mass % or less, Cu: 0.60 mass % or less, Mn: 2.00 mass % or less, Mg: 0.40 mass % or less, Cr: 0.10 mass % or less, Zn: 1.50 mass % or less, Ti: 0.10 mass % or less, and B: 0.10 mass % or less, the remainder being Al and unavoidable impurities. 
     
     
         8 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.20-2.00 mass % Si. 
     
     
         9 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.40-2.00 mass % Mn. 
     
     
         10 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.10-0.60 mass % Fe. 
     
     
         11 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.05-0.60 mass % Cu. 
     
     
         12 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.03-0.40 mass % Cu. 
     
     
         13 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.01-0.10 mass % Cr. 
     
     
         14 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.05-1.50 mass % Zn. 
     
     
         15 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.005-0.10 mass % Ti. 
     
     
         16 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition contains 0.005-0.10 mass % B. 
     
     
         17 . The extruded, multi-hole-pipe manufacturing method according to  claim 1 , wherein the aluminum alloy composition consists of 0.70-2.00 Si, 0.15-0.50 mass % Fe, 1.00-2.00 mass % Mn, 0.05-0.30 mass % Mg, 0.02-0.10 mass % Cr, 0.10-1.00 mass % Zn, and 0.005-0.10 mass % Ti, the remainder being Al and unavoidable impurities. 
     
     
         18 . The extruded, multi-hole-pipe manufacturing method according to  claim 17 , wherein at least 45 mass % of casting materials used to prepare the ingot are aluminum scrap material. 
     
     
         19 . The extruded, multi-hole-pipe manufacturing method according to  claim 18 , wherein the first hold temperature is in the range of 580° C. to 620° C. and the first hold temperature is in the range of 450° C. to 540° C. 
     
     
         20 . A method, comprising:
 providing an aluminum alloy composition containing one or more alloying elements selected from the group consisting of Si: 2.00 mass % or less, Fe: 0.60 mass % or less, Cu: 0.60 mass % or less, Mn: 2.00 mass % or less, Mg: 0.40 mass % or less, Cr: 0.10 mass % or less, Zn: 1.50 mass % or less, Ti: 0.10 mass % or less, and B: 0.10 mass % or less, with the proviso that the total of the Si content and the Mn content is 3.20 mass % or less, and the Si content is less than the Mn content;   holding the aluminum alloy composition at a first hold temperature of 550° C.-650° C. for at least 2 hours;   subsequently holding the aluminum alloy composition at a second hold temperature of 450° C.-540° C. for at least 3 hours; and   subsequently subjecting the aluminum alloy composition to hot extrusion to form a multi-hole pipe.