Architectural aluminum alloy material and process for manufacturing the same

Abstract

There is provided an architectural Al alloy material which undergoes minor loss of proof stress even after a baking finish treatment at a high temperature of 260 to 280° C. and which can be subjected to acute-angle bending, as well as, a process for manufacturing the same. This architectural Al alloy material, which is a hot rolled JIS A3003 material, contains a fiber structure and a recrystallized grain structure having an area ratio of 20 % or less after a baking finish treatment at 300° C. or lower, and undergoes a proof stress loss of 10% or less after the baking finish treatment. The Al alloy material is manufactured only by hot rolling which is carried out under control such that the temperature at the end of rolling be in the range of 290 to 340° C.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to an architectural aluminum (Al) alloy material and a process for manufacturing the same. More specifically, the present invention relates to an architectural Al alloy material, which is to be put into practical uses as a building material with the premise that it is subjected to a baking finish treatment in a high temperature region of 260 to 280.degree. C. and which undergoes minor loss of proof stress and retains sufficient elongation even after the baking finish treatment to show excellent bendability, as well as, to a process for manufacturing the same.[0003] 2. Prior Art[0004] Since Al alloy materials are light, they are used as exterior wall materials and interior finishing materials for high-rise buildings or as curtain wall materials.[0005] In such cases, an Al alloy plate 1 is subjected to 90-degree bending, for example, as shown in FIG. 1. These days, acute-angle bending is on the increase to bend Al al...

AI Technical Summary

Benefits of technology

[0017] It is an object of the present invention to provide an architectural Al alloy material used as a building material on the premise that it is subjected to baking finish treatment, wherein cracking does not occur even when it is subjected to sharp bending or acute-angle bending, since it undergoes minor loss of the proof stress and also has appropriate elongation properties even after the baking finish treatment, and to provide a process for manufacturing it.

[0034] This A3003 material having the structure as described above exhibits the following effects:

[0035] For example, in carrying out acute-angle bending, if the material has the fiber structure only, cracking or the like can occur at the bend along the grain boundary of the fiber structure. However, the A3003 material of the present invention contains the finely divided secondary structure, so that such cracking can be prevented from occurring. In other words, the material ensures acute-angle bending.

[0036] In addition, in the case of the A3003 material, even if it is subjected to a baking finish treatment at a high temperature of 300.degree. C. or lower, more typically at 260 to 280.degree. C., % loss of proof stress after the baking finish treatment is controlled to 10% or less. Even after the baking finish treatment of the material, it secures an absolute proof stress value of 95 N / mm.sup.2 or more, satisfying requirements for the exterior wall material for buildings. Besides, elongation of the material is increased to 27% or more, enabling excellent bending treatment.

[0037] The properties described above, particularly that % loss of proof stress after the baking finish treatment is controlled to 10% or less are the effects to be brought about by the finely divided structure and the fiber structure coexisting in the material. This secondary structure naturally grows into recrystallized grain structure during the baking finish treatment at a high temperature to have increased diameters respectively, and also the quantity of precipitated crystal grains thereof increases.

[0043] A temperature at the beginning of rolling of lower than 350.degree. C. cannot secure a temperature of 290.degree. C. or higher at the end of rolling. This can increase the strength but reduces elongation, causing cracking and the like in bending.

Problems solved by technology

In addition, fiber structures remain in these materials, so that they can be subjected to sharp 90-degree bending.

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