JPH09241785A

JPH09241785A - High toughness aluminum alloy

Info

Publication number: JPH09241785A
Application number: JP8321796A
Authority: JP
Inventors: Toshihiko Kaihatsu; 利彦開発; Shinji Makino; 伸治牧野
Original assignee: Aisin Keikinzoku Co Ltd
Current assignee: Aisin Keikinzoku Co Ltd
Priority date: 1996-03-12
Filing date: 1996-03-12
Publication date: 1997-09-16

Abstract

PROBLEM TO BE SOLVED: To improve strength and productivity by specifying an alloy composition and heat treatment conditions, respectively. SOLUTION: In this die cast product Cu and Mg are incorporated to aim at the strengthening of precipitation by T6 treatment, and this cast product is made of Al alloy having an alloy composition containing, by weight, <=4.5% Cu, 4.0-13.0% Si, and <=0.7% Mg and is a heat treated product prepared by performing aging treatment after solution heat treatment. This heat treated product is prepared by performing solution heat treatment in the air at 440-490 deg.C for 1-6hr, rapid cooling, and then aging treatment at 120-180 deg.C for 2-7hr. Moreover, the residual gas, on the reverse side of a gate, in the die cast product is regulated to <10cc/100gAl. At this time, the residual gas is constituted of <=4.5cc of N2 , <=2.3cc of H2 , and <=3.2cc of carbonaceous gas, and further, as to the number of blisters in the die cast product, blisters of not less than 1mm×1mm for 2000cm<2> expressed in terms of surface are 2-23 pieces and those of 1mm×1mm or less are 55-200 pieces.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、バンパ・リィンホ
ースメントまたはインパクトビーム等の自動車用衝撃吸
収部材に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock absorbing member for automobiles such as a bumper / line reinforcement or an impact beam.

【０００２】[0002]

【従来の技術】従来、バンパ・リィンホースメントまた
はインパクトビーム等の自動車用衝撃吸収部材の材料と
して、Ａｌ−Ｚｎ−Ｍｇ系合金が使用されている。ま
た、高強度を維持しつつ、押出性に優れた合金も開発さ
れている（特開平７−２６８５３３号）。2. Description of the Related Art Conventionally, Al--Zn--Mg alloys have been used as materials for automobile shock absorbing members such as bumpers, reinforcements and impact beams. Further, an alloy having excellent extrudability while maintaining high strength has been developed (Japanese Patent Laid-Open No. 7-268533).

【０００３】[0003]

【本発明が解決しようとする課題】しかし、強度向上を
図るためにＺｎ、Ｍｇ等を添加すると、靭性が非常に悪
化してしまい、バンパ・リィンホースメント等に採用す
ると、衝突時に亀裂が発生してしまい、逆に、衝撃エネ
ルギーの吸収量が減少するという技術課題があった。ま
た、亀裂部が鋭角になり、その部分が人に傷害を与える
恐れが高く、人員保護の観点からも大きな問題になって
いた。そこで、０．２％耐力（以下、耐力と略す）を３
５０〜４００ＭＰａを維持しつつ、靭性に優れた材料を
得るべく精意研究した結果、本発明に至ったものであ
る。However, if Zn, Mg, etc. are added for the purpose of improving the strength, the toughness is extremely deteriorated, and if it is used in bumpers, reinforcements, etc., cracks occur at the time of collision. On the contrary, there is a technical problem that the absorption amount of impact energy is reduced. Further, the cracked portion becomes an acute angle, and there is a high possibility that the cracked portion will injure a person, which is a serious problem from the viewpoint of protecting personnel. Therefore, 0.2% proof stress (hereinafter abbreviated as proof stress) is 3
The present invention has been achieved as a result of intensive research to obtain a material having excellent toughness while maintaining 50 to 400 MPa.

【０００４】[0004]

【課題を解決するための手段】Ａｌ−Ｚｎ−Ｍｇ系合金
にて引張強度および耐力を向上させるためにＭｇを添加
することは効果的であるが、逆に、材料が硬くなるため
に靭性は低下するものと、当該技術分野にて広く認識さ
れているところである。ところが、合金成分およびビレ
ット鋳造後の均質化処理条件を種々検討した結果、一定
の範囲にては耐力および靭性がともに優れることが明ら
かになった。以下、具体的に説明する。[Means for Solving the Problems] It is effective to add Mg to improve tensile strength and proof stress in an Al-Zn-Mg alloy, but conversely, since the material becomes hard, the toughness is It is widely recognized in the art that it will decrease. However, as a result of various studies on alloy components and homogenization treatment conditions after billet casting, it was revealed that both yield strength and toughness were excellent in a certain range. Hereinafter, a specific description will be given.

【０００５】Ｍｇ成分を０．８５〜０．９９ｗｔ％（以
下、％と略す）にして、Ｚｎ成分を６．４〜６．８％に
することで、後述する他の成分との組み合わせにて耐力
３５０〜４００ＭＰａを得ることができる。Ｍｇを１．
００％以上にすると、耐力はさらに向上するが、押出加
工性および靭性が急激に悪くなり、０．８５％未満にな
ると靭性の変化は少ないが、耐力が急激に低下してしま
う。特に、Ｚｎ成分を６．４〜６．８％とすることで、
かかるＭｇ成分の効果を維持しつつ、靭性の向上、耐応
力腐食割れ性の向上が図れ、押出加工性も維持できる。
Ｍｎ成分は、繊維状組織の安定化を図り、靭性向上に有
効であり、０．０８〜０．１８％が適正な範囲である。
０．０８％未満では効果が弱く、０．１８％を超えると
押出材組織粒界部に偏析しやすくなり、かえって逆効果
となる。Ｃｕ成分は、耐応力腐食割れ性を維持するのに
有効であり、０．１０〜０．２０％の範囲が適切であ
り、０．２０％を超えると耐食性が悪くなる。Ｃｒ、Ｚ
ｒ成分は、粗大再結晶化を抑制し、繊維状組織を維持す
るのに有効であり、その適正範囲はＣｒ成分０．０３〜
０．１０％、Ｚｒ成分０．１０〜０．２０％である。Ｔ
ｉ成分は、結晶粒の微細化に有効であり、ビレット鋳造
品質を維持するのに必要である。By combining the Mg component with 0.85 to 0.99 wt% (hereinafter abbreviated as%) and the Zn component with 6.4 to 6.8%, it is possible to combine with other components described later. A yield strength of 350 to 400 MPa can be obtained. Mg is 1.
If it is more than 00%, the yield strength will be further improved, but the extrudability and toughness will be drastically deteriorated, and if it is less than 0.85%, the toughness will be drastically lowered although the change in toughness is small. In particular, by setting the Zn component to 6.4 to 6.8%,
While maintaining the effect of the Mg component, the toughness and stress corrosion cracking resistance can be improved, and the extrudability can be maintained.
The Mn component is effective in stabilizing the fibrous structure and improving the toughness, and 0.08 to 0.18% is an appropriate range.
If it is less than 0.08%, the effect is weak, and if it exceeds 0.18%, segregation tends to occur in the grain boundary of the extruded material structure, which is rather the opposite effect. The Cu component is effective for maintaining the stress corrosion cracking resistance, and the range of 0.10 to 0.20% is appropriate, and if it exceeds 0.20%, the corrosion resistance deteriorates. Cr, Z
The r component is effective in suppressing coarse recrystallization and maintaining a fibrous structure, and the appropriate range is from 0.03 to Cr component.
0.10% and Zr component 0.10 to 0.20%. T
The i component is effective for refining crystal grains and is necessary for maintaining the billet casting quality.

【０００６】以上のような成分配合からなるアルミニウ
ム合金を、常用手段を用いて所定の円柱ビレットを鋳造
し、その後に４２０〜５２０℃にて４〜２４時間均質化
処理する。ここで、ビレットの均質化処理条件もその後
の押出形材にて適正な耐力、靭性、および応力腐食割れ
性を得るために重要であり、４２０℃以下では耐応力腐
食割れ性が悪化し、５２０℃以上では耐力、靭性が低下
する。このようにして得られたビレットを用いて、通常
実施されている直接または間接押出プレス機にて、押出
加工後に所定の人工時効処理をすることにより、高強
度、高靭性で耐応力腐食割れ性に優れたバンパ・リィン
ホースメント、インパクトビーム等に供することができ
るアルミニウム押出形材が得られる。The aluminum alloy having the above-mentioned composition is cast into a predetermined cylindrical billet by a conventional means, and then homogenized at 420 to 520 ° C. for 4 to 24 hours. Here, the homogenization treatment condition of the billet is also important for obtaining appropriate yield strength, toughness, and stress corrosion cracking resistance in the subsequent extruded profile, and stress corrosion cracking resistance is deteriorated at 420 ° C. or lower. If the temperature is above ℃, the yield strength and toughness will decrease. Using the billet obtained in this way, with a commonly used direct or indirect extrusion press, by performing a predetermined artificial aging treatment after extrusion, high strength, high toughness and stress corrosion cracking resistance It is possible to obtain an extruded aluminum profile that can be used for bumper / line hosement, impact beam, etc.

【０００７】[0007]

【発明の実施の形態】本発明に基づくアルミニウム合金
にて、直径２０４ｍｍ、長さ９００ｍｍの円柱ビレット
を鋳造し、３０００ｔｏｎ油圧押出プレスを用いて板厚
１．５ｍｍ×幅１００ｍｍの形材を押し出して、引張強
度、耐力、耐応力腐食割れ性および靭性を評価した。そ
の時に用いた合金組成を表１に示し、評価結果を表２に
て示す。なお、発明の効果を確保すべく、比較合金例に
ついても同様に示す。BEST MODE FOR CARRYING OUT THE INVENTION A cylindrical billet having a diameter of 204 mm and a length of 900 mm is cast from an aluminum alloy according to the present invention, and a section material having a thickness of 1.5 mm and a width of 100 mm is extruded using a 3000 ton hydraulic extrusion press. , Tensile strength, proof stress, stress corrosion cracking resistance and toughness were evaluated. The alloy composition used at that time is shown in Table 1, and the evaluation results are shown in Table 2. In addition, in order to secure the effect of the invention, the comparative alloy examples are also shown.

【０００８】 [0008]

【０００９】 [0009]

【００１０】[0010]

【発明の効果】本発明の効果と評価方法を示しながら、
具体的に説明する。引張強度および０．２％耐力は、Ｊ
ＩＳ５号片の大きさに切り出し、評価した。図１に示す
ように、靭性は本発明によるアルミニウム合金および従
来合金を用いて押出成形した板材を治具にて円形状に固
定し、上部から先端所定Ｒのパンチにて負荷を加え、そ
の際の変位−荷重線図を図２に示すように求めた。従来
の高強度アルミニウム合金は（ａ）のような変位−荷重
線を一般に示した。それに対して、本発明によるアルミ
ニウム合金を用いると、（ｂ）に示すような変位−荷重
線になる。これは、従来の高強度アルミニウム合金の場
合には、最大荷重付近で材料に亀裂が発生すると、すぐ
に大きく成長して割れとなり、荷重が急降下するのに対
して、本発明合金による場合には割れが生じにくく、い
わゆる「ねばり」があり、徐々に荷重が降下するためで
ある。表２に示す靭性の値は、比較合金５における変位
−荷重積分値を１００とした場合の比較値として示した
ものである。耐応力腐食割れ性は、一定応力を負荷した
試験片を酸化クロム：３６ｇ／ｌ、ニクロム酸カリウ
ム：３０ｇ／ｌ、塩化ナトリウム：３ｇ／ｌからなる５
０℃水溶液に７２時間浸漬後、クラックの発生状況を評
価したものであり、「○」はクラック発生が認められな
いことを示し、「×」はクラックが発生したことを示
す。本発明によるアルミニウム合金の場合には、靭性が
向上しただけでなく、耐応力腐食割れ性も向上した。The effects of the present invention and the evaluation method are shown below.
This will be specifically described. Tensile strength and 0.2% proof stress are J
The piece was cut into a size of IS5 piece and evaluated. As shown in FIG. 1, as toughness, a plate material extruded using an aluminum alloy according to the present invention and a conventional alloy was fixed in a circular shape by a jig, and a load was applied from above with a punch having a predetermined tip R, at that time. The displacement-load diagram of was obtained as shown in FIG. Conventional high-strength aluminum alloys generally exhibit a displacement-load line as shown in (a). On the other hand, when the aluminum alloy according to the present invention is used, the displacement-load line is as shown in (b). This is because in the case of the conventional high-strength aluminum alloy, when a crack occurs in the material near the maximum load, it immediately grows large and becomes a crack, and the load drops sharply, whereas in the case of the alloy of the present invention, This is because cracking is less likely to occur, there is so-called "stickiness", and the load gradually drops. The toughness values shown in Table 2 are shown as comparative values when the displacement-load integral value in Comparative Alloy 5 is 100. The resistance to stress corrosion cracking consists of chromium oxide: 36 g / l, potassium dichromate: 30 g / l, and sodium chloride: 3 g / l for a test piece loaded with a constant stress.
After being immersed in a 0 ° C. aqueous solution for 72 hours, the state of occurrence of cracks was evaluated. “◯” indicates that no crack was observed, and “x” indicates that a crack occurred. In the case of the aluminum alloy according to the present invention, not only the toughness was improved, but also the stress corrosion cracking resistance was improved.

【図面の簡単な説明】[Brief description of drawings]

【図１】靭性の評価方法の概要図を示す。FIG. 1 shows a schematic diagram of a toughness evaluation method.

【図２】図１に示す方法にて得られた変位に対する荷重
線図を示す。FIG. 2 shows a load diagram for displacement obtained by the method shown in FIG.

【符号の説明】[Explanation of symbols]

１・・・・・・供試材２、２´・・・供試材を固定するための上治具３・・・・・・供試材を固定するための下治具４・・・・・・供試材に負荷を加えるパンチ（ａ）・・・・従来合金における変位−荷重線図（ｂ）・・・・本発明合金における変位−荷重線図 1 --- Test material 2, 2 '... Upper jig for fixing test material 3 ...- Lower jig for fixing test material 4 ...・・・ Punch that applies load to test material (a) ・・・ Displacement-load diagram in conventional alloy (b) ・・・・ Displacement-load diagram in alloy of the present invention

Claims

【特許請求の範囲】[Claims]

【請求項１】Ｚｎ：６．４〜６．８ｗｔ％、Ｍｇ：
０．８５〜０．９９ｗｔ％、Ｃｕ：０．１０〜０．２０
ｗｔ％、Ｍｎ：０．０８〜０．１８ｗｔ％、Ｃｒ：０．
０３〜０．１０ｗｔ％、Ｚｒ：０．１０〜０．２０ｗｔ
％、Ｔｉ：０．０１〜０．１０ｗｔ％を含み、残部Ａｌ
と不可避不純物からなり、４２０〜５２０℃にて４〜２
４時間均質化処理することを特徴とするアルミニウム合
金。1. Zn: 6.4 to 6.8 wt%, Mg:
0.85-0.99wt%, Cu: 0.10-0.20
wt%, Mn: 0.08 to 0.18 wt%, Cr: 0.
03-0.10 wt%, Zr: 0.10-0.20 wt
%, Ti: 0.01 to 0.10 wt%, balance Al
And unavoidable impurities at 420 to 520 ℃ for 4 to 2
An aluminum alloy characterized by being homogenized for 4 hours.