JP5354928B2 - Composite aluminum alloy extruded material for welded structures - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow extruded material of an aluminum alloy for a weld structure, which shows superior formability in particular in a part of a cross section and superior weldability in particular in the other part of the cross section. <P>SOLUTION: A bumper reinforcing member 35 is formed of the extruded material of the aluminum alloy; and the cross section is constituted by a part formed of a 6000 series aluminum alloy (top and bottom webs 39 and 40) and a part formed of a 7000 series aluminum alloy (front and back flanges 36 and 37, and middle web 38). A front-end of a transversely crushing type stay 42 formed of the extruded material of the 7000 series aluminum alloy is welded (welded part 44) to the back flange 37 of the bumper reinforcing member 35. The bumper reinforcing member 35 and the stay 42 are aged on an aging treatment condition of the 6000 series aluminum alloy before or after the welding step. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a composite aluminum alloy extruded material for welded structures.

  The hollow extruded material of 6000 series aluminum alloy specified by JIS is generally excellent in strength, formability, corrosion resistance, etc., and has few alloying elements and is excellent in recyclability. It has been proposed to be used for applications (energy absorbing members) such as reinforcing materials and door beams. On the other hand, the 7000 series aluminum alloy hollow extruded material has higher strength and relatively high joint efficiency in both cases of aging treatment after welding and welding after aging treatment (see, for example, Table 3 of Patent Document 1). Application to the above-mentioned use is recommended when joining with a member by welding or the like.

JP 2002-115037 A

  Although it is desirable to use a 7000 series aluminum alloy having excellent weldability and high strength as the aluminum alloy extruded material for welded structures, the 7000 series may have insufficient formability and corrosion resistance depending on the application. For example, an extruded material with a mouth-shaped cross section consisting of a horizontal upper and lower web and front and rear flanges (impact surface side and car body side) that are connected vertically is used as a bumper reinforcement, and the tip of the bumper stay or crash box is welded to the car body side flange. For example, when joining. It is desirable that the upper and lower webs have excellent formability because they can be greatly buckled and deformed at the time of collision. However, in the case of 7000 series aluminum alloy, the formability is insufficient, and the web may crack and cannot absorb enough energy. It is done. On the other hand, when a 6000 series aluminum alloy is applied to such a bumper reinforcing material, there is a problem that joint efficiency is greatly reduced in the welded portion.

Thus, in the aluminum alloy hollow extruded material for welded structure, it is required that the weldability is particularly excellent in a part of the cross section, and the properties other than the weldability, such as formability and corrosion resistance, are particularly excellent in the other part of the cross section. May be required. However, the current 6000 series and 7000 series aluminum alloy hollow extruded materials cannot sufficiently satisfy both requirements.
This invention is made | formed in view of such a problem, and it aims at obtaining the aluminum alloy hollow extrusion material for welded structures which can respond to both said requirements.

The aluminum alloy hollow extruded material for welded structure according to the present invention has a hollow cross section composed of a portion made of 6000 series aluminum alloy and a portion made of 7000 series aluminum alloy, and the portion made of 6000 series aluminum alloy and the 7000 series aluminum alloy. These parts are composite aluminum alloy extruded materials welded to each other during extrusion.
The 6000 series and 7000 series are alloy systems defined in JIS, and are Al-Mg-Si- (Cu) -based and Al-Zn-Mg- (Cu) -based stretched materials, respectively. These are all heat-treatable aluminum alloys, and the composite aluminum alloy extruded material for welded structures according to the present invention is also subjected to aging treatment after press quenching or aging treatment after solution treatment by reheating. The aging treatment is performed before or after welding, and is generally desirably performed under conditions that make the 6000 series aluminum alloy have high strength (overaging range for 7000 series).

The aluminum alloy hollow extruded material for welded structure according to the present invention is relatively excellent in weldability at a portion made of 7000 series aluminum alloy, relatively excellent in formability at a portion made of 6000 series aluminum alloy, and corrosion resistance. It has excellent characteristics of both 6000 series and 7000 series.
The aluminum alloy hollow extruded material for welded structure according to the present invention can be suitably applied to energy absorbing members such as bumper reinforcing materials, side members, instrument panel reinforcing materials, door beams and the like of automobiles.

1-3 shows an example of a cross-sectional structure of an aluminum alloy hollow extruded material for welded structure according to the present invention.
FIG. 1 shows an application of the present invention to a bumper reinforcing member having a mouth-shaped cross section. When attached to a vehicle body, front and rear (impact surface side and vehicle body side) flanges 1 and 2 are made of a 7000 series aluminum alloy. The upper and lower webs 3 and 4 perpendicular to the front and rear flanges 1 and 2 are made of a 6000 series aluminum alloy. The front and rear flanges 1 and 2 and the upper and lower webs 3 and 4 are welded to each other at the time of extrusion to form an extruded profile in which the mouth section is completely integrated. This extruded shape is subjected to aging treatment after press quenching or aging treatment after reheating and solution treatment. The aging treatment is performed before or after welding. In the former case, welding is performed on the press-quenched material or solution treatment material, and in the latter case, welding is performed on the aging treatment material.

When, for example, a reinforcing material (see JP-A-6-286536) is welded to the front flange 1 and, for example, the tip of a bumper stay or crash box is welded to the rear flange 2, both flanges 1 and 2 are excellent in weldability 7000. Since it is made of an aluminum alloy, the joint efficiency is high. On the other hand, the bumper reinforcing material is generally bent at both ends, but the front and rear webs 3 and 4 subjected to in-plane bending are made of a 6000 series aluminum alloy having excellent formability, so that bending is easy. Further, when the bumper reinforcing material is crushed and deformed at the time of collision from the front (to the front flange 1), the upper and lower webs 3 and 4 having large deformation are made of 6000 series aluminum alloy having excellent formability, so that they are cracked while having high strength. Can be prevented.
In addition, when performing the aging process of a bumper reinforcement after welding, if the other member welded to the bumper reinforcement is made of a 6000 series or 7000 series aluminum alloy, these can be aged simultaneously.

  FIG. 2 shows a case where the present invention is applied to a bumper stay of a lateral crushing type (see Japanese Patent Application Laid-Open No. 2005-14836). The front and rear (impact surface side and vehicle body side) flanges 11 and 12 are made of a 7000 series aluminum alloy, and the webs 13 and 15 on both sides of the webs 13 to 15 perpendicular to the front and rear flanges 11 and 12 are made of a 6000 series aluminum alloy. The intermediate web 14 is made of the same 7000 series aluminum alloy as the front and rear flanges 11 and 12. The front and rear flanges 11 and 12 and the webs 13 and 15 are welded to each other at the time of extrusion to form a completely integrated extruded material. This extruded material is subjected to aging treatment after press quenching, or aging treatment after reheating and solution treatment. The aging treatment is performed before or after welding.

  For example, when the front flange 11 is welded to the rear flange of the bumper reinforcement (see the rear flange 2 in FIG. 1) and the rear flange 12 is welded to the tip of the side member, both flanges 11 and 12 are made weldable. Since it is made of an excellent 7000 series aluminum alloy, the joint efficiency is high. On the other hand, when the bumper stay is crushed at the time of a collision from the front, since the webs 13 and 15 having a large deformation are made of a 6000 series aluminum alloy having excellent formability, the occurrence of cracks can be prevented while having high strength.

  FIG. 3 shows a case where the present invention is applied to a side member having a rectangular cross section. When the flange extruding direction is arranged in the front-rear direction, the upper half 21 is made of a 6000 series aluminum alloy and the lower half 22 is a 7000 series aluminum alloy. Consists of. The upper half 21 and the lower half 22 are welded to each other during extrusion to form a completely integrated extruded shape. This extruded material is subjected to aging treatment after press quenching, or aging treatment after reheating and solution treatment. The aging treatment is performed before or after welding. This aging treatment is desirably performed under the condition that the strength of the 6000 series aluminum alloy is high (overaging range for 7000 series) so that a large strength difference does not occur between the upper half 21 and the lower half 22.

  For example, when a bracket of an under-run protector (see Japanese Patent Application Laid-Open No. 2006-88905) is welded to the lower half portion 22, the lower half portion 22 is made of a 7000 series aluminum alloy having excellent weldability, so that the joint efficiency is high. On the other hand, the upper half 21 and the lower half 22 are made of different alloy-based aluminum alloys, but if the difference in strength between them is not large (the strength difference from the 6000 series is reduced by over-aging the 7000 series). In addition, it is possible to easily perform a cross-sectional design assuming compression deformation at the time of collision.

  In the 6000 series and 7000 series aluminum alloys according to the present invention, the former contains Mg: 0.4 to 1.2% (mass%, the same applies hereinafter) and Si: 0.2 to 1.3% as the main components. In general, 6000 series and 7000 series aluminum alloys containing Zn: 4.0-7.0% and Mg: 0.5-1.5% can be used. The former includes, for example, JIS6063, 6N01, 6061, and 6082, and the latter includes, for example, JIS7N01, 7003, and 7075.

In order to produce the aluminum alloy hollow extruded material according to the present invention, for example, an extrusion method described in JP-A No. 5-38940 or JP-A No. 7-60340 can be applied.
In the method of Japanese Patent Laid-Open No. 5-38940, two semi-circular billets having different alloy systems are combined into one cylindrical billet, heated to the extrusion temperature and accommodated in a container. At this time, aluminum alloys of different alloy systems are used. This is a method in which billets are set in containers so that they enter different entry ports, and the metal from each entry port is extruded through a hollow extrusion die. When this is applied to the present invention, a billet of 6000 series and 7000 series may be appropriately combined according to the cross-sectional structure of the target hollow extruded material (combination structure of 6000 series and 7000 series).

  In the method disclosed in Japanese Patent Laid-Open No. 7-60340, a container having a plurality of independent billet receiving holes corresponding to each port hole is disposed at the rear of a hollow extrusion die having a plurality of entry ports, and each billet is received. This is a method in which the billet is accommodated in the hole and pushed out. When this is applied to the present invention, 6000 series and 7000 series billets may be accommodated in each billet accommodation hole in accordance with the cross-sectional structure of the target hollow extruded material (combined structure of 6000 series and 7000 series).

  The composite aluminum alloy extruded material obtained by extrusion molding is subjected to aging treatment after press-quenching (quality T5 specified in JISH0001) or aging treatment after solution treatment (also quality T6). The aging treatment conditions (conditions for obtaining high strength) differ greatly between the 6000 and 7000 systems, and are generally 170 to 210 ° C. × 3 to 9 hours for the 6000 system, and generally 120 to 150 ° C. × 9 to 24 hours for the 7000 system. Is adopted. When the composite aluminum alloy extruded material according to the present invention is aged under the aging conditions of 6000 series, the 7000 series aluminum alloy is generally over-aged, and when aging is treated under the 7000 series aging conditions, the 6000 series aluminum alloy is generally When it is sub-aged and is subjected to an aging treatment under intermediate conditions, generally, a 6000 series aluminum alloy is sub-aged and a 7000 series aluminum alloy is over-aged. In the present invention, the aging treatment conditions of the above-mentioned 6000 series or 7000 series or intermediate conditions between them may be adopted as appropriate, but sub-aging is generally not desirable, and the aging treatment conditions of the 6000 series (high in the 6000 series) It is desirable to perform an aging treatment under the aging treatment conditions for obtaining strength. At this time, the 7000 series is over-aged, and properties such as general corrosion resistance, stress corrosion cracking resistance, and formability are improved as compared with the case where the normal 7000 series aging treatment is performed.

JIS7003 and JIS6063 aluminum alloy billets are divided into four in the longitudinal direction, and as shown in FIG. 4 (a), two divided billets are welded for each aluminum alloy so that the same aluminum alloy is located at the opposite location (welding) 4), one cylindrical composite billet 32 is manufactured, and the composite billet 32 is heated to 500 ° C. by high-frequency heating and accommodated in a container. As shown in FIG. A composite billet 32 is set in the container so that each alloy enters each entry port of a hollow extrusion die 34 having 33, and is extruded into a die cross section and press-hardened. The extruded material was cut to a predetermined size and then bent to obtain a bumper reinforcing material 35 (see FIG. 5A). In the bumper reinforcing member 35, the front and rear flanges 36 and 37 and the intermediate web 38 are made of 7003 aluminum alloy, and the upper and lower webs 39 and 40 are made of 6063 aluminum alloy. It was converted.
As a comparative example, a JIS 7003 aluminum alloy billet was extruded into the same cross section of the die, press-hardened, and bent in the same manner to obtain a bumper reinforcement 41 (see FIG. 5B).

On the other hand, a JIS 7003 aluminum alloy billet was extruded into a cross section of a die, press-hardened, and cut into a predetermined dimension to form a stay 42. Subsequently, the stays 42 are arranged at two positions on the back surface of the flange 37 of the bumper reinforcement 35 so that the extrusion direction is orthogonal to the extrusion direction of the bumper reinforcement 35 (the vertical direction of the vehicle body), and welding ( A bumper structure 45 was formed as a welded portion 44). Similarly, the stay 42 was welded to the bumper reinforcement 41 to form a bumper structure 46. Subsequently, the bumper structures 45 and 46 were subjected to an aging treatment (T5) of 170 ° C. × 6 hr.
Next, as shown in FIG. 6, the bumper structure 45 was placed on a mounting jig 48 fixed on a jig 47, and a pressing jig 49 was lowered to perform a compression test. The bumper structure 46 was similarly subjected to a compression test.

  As a result, the load-displacement curve shown in FIG. 7 was obtained. In the case of the example (bumper structure 45), the bumper reinforcing material 35 was not cracked, but in the case of the comparative example (bumper structure 46), lateral cracks were generated on both side surfaces (upper and lower webs) of the bumper reinforcing material 35. This appears in the load-displacement curve as a sudden drop in load (indicated by a white arrow).

It is sectional drawing which illustrates the composite aluminum alloy extrusion material which concerns on this invention. It is sectional drawing which illustrates the composite aluminum alloy extrusion material which concerns on this invention. It is sectional drawing which illustrates the composite aluminum alloy extrusion material which concerns on this invention. It is the perspective view (a) of the composite billet used for the Example, and the rear view (b) of an extrusion die. It is a partial cross section figure of the bumper structure (bumper reinforcement material + stay) used for the Example. It is explanatory drawing of the compression test of an Example. It is a graph of the load-displacement curve obtained by the compression test of the Example.

Explanation of symbols

1, 2 Bumper reinforcement flanges 3 and 4 Same web 11 and 12 Bumper stay flanges 13 to 15 Same web 21 Upper half portion 22 Same lower half portion 32 Composite billet 33 Extrusion die entry port 35 and 41 Bumper Reinforcing material 36, 37 Bumper reinforcing material flange 38-40 Same web 42 Bumper stay 45, 46 Bumper structure

Claims (2)

In an aluminum alloy extruded shape having a hollow cross section, the cross section is composed of a part made of a 6000 series aluminum alloy and a part made of a 7000 series aluminum alloy, and a part made of the 6000 series aluminum alloy and a part made of a 7000 series aluminum alloy A composite aluminum alloy extruded material for welded structures, which is welded to each other during extrusion. It is an aging treatment material, The composite aluminum alloy extrusion material for welded structures described in Claim 1 characterized by the above-mentioned.

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