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Alluminum alloy pipe and aluminum alloy structural member for automobile using the same

a technology of aluminum alloy and structural parts, which is applied in the field of aluminum alloy pipes and aluminum alloy structural parts for automobiles, can solve the problems of insufficient weight reduction effect, low toughness of articles, and difficulty in manufacturing thin articles of cast or die-cast aluminum alloys having a relatively large size, so as to achieve lower fluctuations in strength and fatigue strength, and the effect of high reliability

Inactive Publication Date: 2008-08-28
FURUKAWA SKY ALUMINUM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an aluminum alloy pipe for hot working that has a specific shape while maintaining required strength. By limiting the amounts of certain elements in the alloy, the amount of cavities generated during hot working can be reduced. The invention also provides an automobile structural member made of the aluminum alloy pipe, which has higher reliability and lower fluctuations of strength and fatigue strength. The alloy composition of the aluminum alloy pipe includes specific amounts of Mg, Si, Fe, and Cr, with the balance being inevitable impurities and Al. The area ratio of cavities after hot working is controlled within specific ranges. The invention also provides methods for manufacturing the aluminum alloy pipe and the automobile structural member using the specific alloy composition.

Problems solved by technology

However, it is difficult to manufacture thin articles of cast or die-cast aluminum alloys having a relatively larger size, and the effect of making weight lighter is not sufficient.
Since the cast and die-cast articles have low toughness as compared with draw materials such as extruded materials or sheets, and the articles are not completely appropriate for the parts required to have toughness.
However, since the above-mentioned methods are based on cold working, it was a problem that the material is cracked when it is worked into a complex shape.
However, a convention aluminum alloy pipe has the following problems that fatigue strength may be decreased due to coarsening of crystal grains, fluctuations of tensile strength and fatigue strength may be increased due to generation of cavities, and the thickness of the pipe wall may be locally decreased.
In particular, cavities are conspicuously generated by working such as expanding the aluminum alloy pipe by hot working at a temperature of 350° C. or higher, and characteristics of the material is deteriorated.
However, these conventional alloys are not satisfactory for applying hot working, since they cause problems, such as decrease of tensile strength and fatigue strength due to coarsening of crystal grains and generation of cavities, as well as reduction of local pipe wall thickness.

Method used

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  • Alluminum alloy pipe and aluminum alloy structural member for automobile using the same
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  • Alluminum alloy pipe and aluminum alloy structural member for automobile using the same

Examples

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examples

Manufacture of Aluminum Extruded Pipe and Test

(Examples of Manufacture)

[0052]The alloy having the composition shown in Table 1 was melted and cast into a billet with a diameter of 260 mm, which was homogenized at 530° C. for 4 hours. The billet was heated at 480° C., extruded at an extrusion rate of 5 m / minute, and formed into a round pipe with an outer diameter of 95 mm and a pipe wall thickness of 3.5 mm. This round pipe (outer diameter 95 mm, pipe wall thickness 3.5 mm) was cut into a length of 300 mm, and the piece of the round pipe was heated at 500° C. and was inserted into a die heated at 500° C. as shown in FIGS. 1(a) and 1(b). FIG. 1(a) is a front view of the die 1. Die 1 has a pipe insertion part 2. A division part is shown by the reference numeral 1a in FIG. 1(a). FIG. 1(b) shows a cross section of the die.

[0053]Then, the alloy pipe (round pipe) was inserted into the die shown in FIGS. 1(a) and 1(b), and was expanded by the steps described in FIGS. 2(a), 2(b), 2(c) and 2(...

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Abstract

An Al—Mg-based aluminum alloy pipe for hot working, having an alloy composition having from 2.5% by mass to 2.8% by mass of Mg, 0.25% by mass or less of Si, 0.35% by mass or less of Fe, and from 0.25% by mass to 0.35% by mass of Cr, with the balance being inevitable impurities and Al, wherein an area ratio of cavities after hot working is 2.3% or less; and an aluminum alloy structural member for automobile using the same.

Description

TECHNICAL FIELD[0001]The present invention relates to an aluminum alloy pipe and an aluminum alloy structural member for automobile using the same.BACKGROUND ART[0002]Automobile parts have been required to be light-weight in recent years. For attaining the above, cast and die-cast articles of an aluminum alloy have been used in place of parts manufactured by welding and assembling a plurality of steel sheets or steel pipes by pressing or bending. However, it is difficult to manufacture thin articles of cast or die-cast aluminum alloys having a relatively larger size, and the effect of making weight lighter is not sufficient. Since the cast and die-cast articles have low toughness as compared with draw materials such as extruded materials or sheets, and the articles are not completely appropriate for the parts required to have toughness.[0003]On the other hand, as an example for using a drawn material, forming a part having a complex shape by combining bending, crushing and hydroform...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22F1/047
CPCB21C37/065C22F1/047C22C21/06
Inventor KASHIWAZAKI, KAZUHISASHOJI, RYOUENO, SEIZOAKIYAMA, HIROSHISHIOTSUKI, KATSUHIROHORI, IZURUUKENA, TOSHIYASU
Owner FURUKAWA SKY ALUMINUM CORP
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