JPH10298723A - Manufacture of aluminum alloy die casting - Google Patents
Manufacture of aluminum alloy die castingInfo
- Publication number
- JPH10298723A JPH10298723A JP10902997A JP10902997A JPH10298723A JP H10298723 A JPH10298723 A JP H10298723A JP 10902997 A JP10902997 A JP 10902997A JP 10902997 A JP10902997 A JP 10902997A JP H10298723 A JPH10298723 A JP H10298723A
- Authority
- JP
- Japan
- Prior art keywords
- phase
- concentration
- die
- corrosion resistance
- alloy
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
Abstract
Description
【0001】[0001]
【発明の属する技術分野】本発明は、耐食性に優れたア
ルミニウム合金ダイカスト品の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum alloy die-cast product having excellent corrosion resistance.
【0002】[0002]
【従来の技術】アルミニウム合金鋳物をダイカスト法に
よって製造する場合、Al−Si−Cu系合金(例えば
ADC12)が多用されている。この合金には耐食性を
低下させるCuが1.5〜4.0重量%含まれているた
め、得られたダイカスト品の耐食性が低下するという欠
点がある。そこで耐食性を向上させるためにCu含有量
を少なくすると強度が低下するという問題が生じる。ま
た、溶湯を大気中で金型キャビティ中に高速高圧で充填
する普通ダイカスト法によれば、得られたダイカスト品
の内部には鋳造時に巻き込まれた多数の気泡が存在し、
通常の溶体化処理(溶体化温度:500℃前後)を行な
うと、それが膨張して表面にブリスターと呼ばれる欠陥
が発生する。特開昭56−163246号には、鋳造時
に気泡を巻き込まないアキュラッド法、低速ダイカスト
法などで製造したダイカスト品を、450〜530℃に
加熱する熱処理ダイカストの製造方法が開示されている
が、このような特殊なダイカスト法ではコストが高くな
る等の問題がある。2. Description of the Related Art When an aluminum alloy casting is manufactured by a die casting method, an Al-Si-Cu alloy (for example, ADC12) is frequently used. Since this alloy contains 1.5 to 4.0% by weight of Cu which lowers the corrosion resistance, there is a disadvantage that the corrosion resistance of the obtained die-cast product is lowered. Therefore, when the Cu content is reduced in order to improve the corrosion resistance, there is a problem that the strength is reduced. In addition, according to the ordinary die casting method in which the molten metal is filled into the mold cavity at high speed and high pressure in the atmosphere, there are many bubbles entrained during casting in the obtained die cast product,
When a normal solution treatment (solution solution temperature: around 500 ° C.) is performed, it expands and a defect called a blister occurs on the surface. Japanese Patent Application Laid-Open No. 56-163246 discloses a method for producing a heat-treated die cast by heating a die-cast product manufactured by an accurate method or a low-speed die-cast method that does not involve air bubbles during casting to 450 to 530 ° C. Such a special die casting method has problems such as an increase in cost.
【0003】[0003]
【発明が解決しようとする課題】したがって本発明は十
分な強度を持ち、かつ耐食性に優れたアルミニウム合金
ダイカスト品を得ることのできる製造方法を提供するこ
とを目的とする。SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a manufacturing method capable of obtaining an aluminum alloy die-cast product having sufficient strength and excellent corrosion resistance.
【0004】[0004]
【課題を解決するための手段】本発明者らは、Al−S
i−Cu系合金の耐食性について鋭意検討の結果、Cu
添加量が同じでも十分な溶体化処理によりAl相のCu
濃度を均一化すると、鋳放しに比べて耐食性が向上する
ことを知見した。すなわち、本発明はAl−Si−Cu
系合金からなる溶湯を大気中で金型キャビティ中に、高
速高圧で充填する簡便な普通ダイカスト法によりダイカ
スト品を鋳造し、このダイカスト品に360〜400℃
の温度で溶体化処理を施すことによりAl相のCu濃度
を均一化して(Si相に接しているAl相において、C
u濃度2.5重量%以上の層が3μm以下になる)、耐
食性を向上させるものである。本発明においては、Al
−Si−Cu系合金としてCu添加量を1.5〜2.0
%とした重量組成を有するADC12を用いることが好
ましい。Means for Solving the Problems The present inventors have proposed Al-S
As a result of intensive studies on the corrosion resistance of the i-Cu alloy, Cu
Even if the amount of addition is the same, the Cu
It has been found that when the concentration is made uniform, the corrosion resistance is improved as compared with as-cast. That is, the present invention relates to Al-Si-Cu
A die-cast product is cast by a simple ordinary die-casting method in which a molten metal made of a system alloy is filled into a mold cavity in the atmosphere at a high speed and a high pressure.
The solution is subjected to a solution treatment at a temperature of 3 to make the Cu concentration of the Al phase uniform (in the Al phase in contact with the Si phase,
The layer having a u concentration of 2.5% by weight or more becomes 3 μm or less), thereby improving the corrosion resistance. In the present invention, Al
-Cu-added amount of 1.5 to 2.0 as a Si-Cu alloy
% ADC12 is preferably used.
【0005】Al−Si−Cu系合金は通常、Al相、
Si相、Cu相から構成される。腐食はSi相周辺のA
l相で選択的に発生するため、耐食性は主にSi相周辺
のAl相のCu濃度で決まる。そしてダイカストは一般
に鋳放しで使用されるが、この場合偏析によりAl相の
Cu濃度がSi相周辺で大幅に増加している。これに対
して本発明によれば、Al相のCu濃度の均一性を高め
ることで、Si相に接しているAl相において、Cu濃
度2.5重量%以上の層が3μm以下まで低下するので
耐食性が向上する。Al相のCu濃度の均一化は溶体化
処理により達成される。Al−Si−Cu系合金におい
ては一般に500℃前後の温度で溶体化処理が行われ
る。しかし上記した普通ダイカスト法では鋳造時に多数
の気泡を内部に巻き込むため、この温度に保持すると内
部の気泡が膨張して表面にブリスターと呼ばれる欠陥が
発生する。そこで溶体化温度を低下させればブリスター
は発生しなくなる。しかしながらCu濃度を均一化する
ためには、Al相のCuの平均濃度が溶体化温度におけ
るCuの固溶度より低いことが必要である。温度が低下
するほどCuの固溶度も低下するから、ブリスターが発
生しない400℃以下の溶体化温度でCu濃度を均一化
するためには、Al相のCuの平均濃度がCuの固溶度
より低くなるようにCu添加量を2.0重量%以下に抑
えることが必要となる。一方、十分な強度を得るために
はCu添加量は1.5重量%以上であることが必要であ
る。そしてこの添加量の範囲で均一化するために溶体化
温度を360℃以上にすることが必要となる。[0005] Al-Si-Cu-based alloys usually have an Al phase,
It is composed of a Si phase and a Cu phase. Corrosion A around Si phase
Since it occurs selectively in the 1 phase, the corrosion resistance is determined mainly by the Cu concentration of the Al phase around the Si phase. Die casting is generally used as-cast. In this case, the concentration of Cu in the Al phase is greatly increased around the Si phase due to segregation. On the other hand, according to the present invention, by increasing the uniformity of the Cu concentration of the Al phase, the layer having a Cu concentration of 2.5% by weight or more in the Al phase in contact with the Si phase is reduced to 3 μm or less. Corrosion resistance is improved. The uniformization of the Cu concentration in the Al phase is achieved by a solution treatment. In the case of Al-Si-Cu alloys, the solution treatment is generally performed at a temperature of about 500 ° C. However, in the above-described ordinary die casting method, a large number of bubbles are entrained in the inside during casting. When the temperature is maintained at this temperature, the inside bubbles expand and a defect called blister occurs on the surface. Therefore, if the solution temperature is lowered, blisters do not occur. However, in order to make the Cu concentration uniform, it is necessary that the average concentration of Cu in the Al phase is lower than the solid solubility of Cu at the solution temperature. Since the solid solubility of Cu decreases as the temperature decreases, the average concentration of Cu in the Al phase must be equal to the solid solubility of Cu in order to make the Cu concentration uniform at a solution temperature of 400 ° C. or less at which blisters do not occur. It is necessary to suppress the Cu addition amount to 2.0% by weight or less so as to be lower. On the other hand, in order to obtain sufficient strength, it is necessary that the added amount of Cu is 1.5% by weight or more. It is necessary to set the solution temperature to 360 ° C. or higher in order to make the content uniform within this range.
【0006】[0006]
【発明の実施の形態】Cu添加量が1.8重量%である
ADC12からなる合金をJIS舟形形状の金型で大気
中、常温で鋳造した。得られたインゴットを340℃、
360℃、380℃、400℃、500℃の各温度で7
時間溶体化処理を行った後、水冷し、試験片を切り出し
た。比較のため鋳放しのインゴットからも試験片を切り
出した。耐食性を評価するためこれらの試験片に対し塩
水噴霧試験(JIS Z2371)を96時間行った。
表面に発生した錆(水酸化アルミニウム)を硝酸で溶解
した後、硝酸中のAl濃度をICP(プラズマ発光分光
分析)で測定することで単位面積当たりの錆の重量を算
出した。その結果を図1に示す。図1から溶体化温度の
上昇と共に耐食性が向上し、360℃以上では鋳放しに
比べて十分高い耐食性を示すことがわかる。BEST MODE FOR CARRYING OUT THE INVENTION An alloy composed of ADC12 with an added amount of Cu of 1.8% by weight was cast in a JIS boat-shaped mold at room temperature in the air. The obtained ingot was heated at 340 ° C.
7 at each of 360 ° C, 380 ° C, 400 ° C, 500 ° C
After performing the solution treatment for a period of time, it was cooled with water, and a test piece was cut out. Specimens were also cut from as-cast ingots for comparison. A salt spray test (JIS Z2371) was performed on these test pieces for 96 hours to evaluate the corrosion resistance.
After dissolving the rust (aluminum hydroxide) generated on the surface with nitric acid, the weight of rust per unit area was calculated by measuring the Al concentration in nitric acid by ICP (plasma emission spectroscopy). The result is shown in FIG. From FIG. 1, it can be seen that the corrosion resistance improves with an increase in the solution heat-up temperature, and that at 360 ° C. or higher, a sufficiently high corrosion resistance is exhibited as compared to as-cast.
【0007】Al相のCu濃度の均一性と耐食性の関係
を明らかにするため、上記と同様の合金を用いて鋳放し
及び360℃、400℃、500℃の各温度で溶体化処
理を行った試験片の元素分布をEPMAを用いて測定し
た。その結果を図2、図3に示す。なお図2(a)、
(b)、図3(a)、(b)はそれぞれ鋳放し、溶体化
温度360℃、同400℃、同500℃の元素分布を示
す。鋳放しではSiのピークの近傍でCuもピークを示
すことが多い(図2(a))。これは偏析によりSi相
周辺のAl相のCu濃度が大幅に増加していることを示
す。溶体化温度360℃ではSi相周辺のCuのピーク
の幅が狭くなり、Cu濃度が2.5重量%以上の層は3
μm以下となっている(図2(b))。これは溶体化処
理によりAl相のCu濃度の均一性が高くなり、Si相
周辺のCu濃度が高い部分が薄くなったことを示す。溶
体化温度400℃及び500℃ではSi相周辺のはっき
りしたピークは見られなくなる(図3(a)、
(b))。これはCu濃度の均一化がさらに進み、Si
相周辺のCu濃度が高い部分がほぼ消滅したことを示
す。これより溶体化温度360℃以上で、Si相に接し
ているAl相においてCu濃度2.5重量%以上の層が
3μm以下になるために、耐食性が十分向上することが
わかる。以上のようにCu濃度を均一化すれば溶体化処
理条件に関係なく高い耐食性が得られると考えられる。[0007] In order to clarify the relationship between the uniformity of the Cu concentration of the Al phase and the corrosion resistance, an as-cast alloy and a solution treatment at 360 ° C, 400 ° C and 500 ° C were performed using the same alloy as described above. The element distribution of the test piece was measured using EPMA. The results are shown in FIGS. In addition, FIG.
3 (b) and FIGS. 3 (a) and 3 (b) show the elemental distributions at the as-cast, solution temperature of 360 ° C., 400 ° C. and 500 ° C., respectively. In the as-cast state, Cu often shows a peak near the peak of Si (FIG. 2A). This indicates that the Cu concentration of the Al phase around the Si phase has increased significantly due to segregation. At a solution temperature of 360 ° C., the width of the Cu peak around the Si phase becomes narrow, and the layer having a Cu concentration of 2.5% by weight or more
μm or less (FIG. 2B). This indicates that the solution treatment increased the uniformity of the Cu concentration in the Al phase, and reduced the portion with a high Cu concentration around the Si phase. At the solution temperature of 400 ° C. and 500 ° C., no clear peak around the Si phase is seen (FIG. 3 (a),
(B)). This is because the Cu concentration becomes more uniform and the Si concentration becomes higher.
This indicates that the portion having a high Cu concentration around the phase has almost disappeared. From this, it can be seen that at a solution temperature of 360 ° C. or more, the layer having a Cu concentration of 2.5% by weight or more becomes 3 μm or less in the Al phase in contact with the Si phase, so that the corrosion resistance is sufficiently improved. It is considered that high corrosion resistance can be obtained regardless of the solution treatment conditions by making the Cu concentration uniform as described above.
【0008】[0008]
【発明の効果】以上の通り、本発明により得られたアル
ミニウム合金ダイカスト品は合金自体が優れた耐食性を
有するので、特に耐食性が要求される塗装なしの製品の
用途の拡大に寄与するところが大きい。As described above, since the aluminum alloy die-cast product obtained by the present invention has excellent corrosion resistance itself, it greatly contributes to the expansion of the use of unpainted products which require corrosion resistance.
【図1】溶体化温度と耐食性の関係を示す図である。FIG. 1 is a diagram showing the relationship between solution temperature and corrosion resistance.
【図2】ダイカスト品の元素分布を示す図である。FIG. 2 is a view showing an element distribution of a die-cast product.
【図3】ダイカスト品の元素分布を示す図である。FIG. 3 is a diagram showing an element distribution of a die-cast product.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 影山 望 埼玉県熊谷市三ヶ尻5200番地日立金属株式 会社熊谷工場内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Nozomu Kageyama 5200 Sankajiri, Kumagaya-shi, Saitama, Hitachi Metals Co., Ltd.
Claims (2)
スト法によりダイカスト品を鋳造し、このダイカスト品
に360〜400℃の温度で溶体化処理を施し、Si相
に接しているAl相におけるCu濃度2.5重量%以上
の層を3μm以下にしたことを特徴とするアルミニウム
合金ダイカスト品の製造方法。1. A die-cast product is cast by a die-casting method using an Al—Si—Cu-based alloy, and the die-cast product is subjected to a solution treatment at a temperature of 360 to 400 ° C. A method for producing an aluminum alloy die-cast product, wherein a layer having a Cu concentration of 2.5% by weight or more is 3 μm or less.
5〜2.0%とした重量組成を有するADC12である
請求項1記載のアルミニウム合金ダイカスト品の製造方
法。2. An Al—Si—Cu alloy having a Cu content of 1.
2. The method for producing an aluminum alloy die-cast product according to claim 1, wherein the ADC12 has a weight composition of 5 to 2.0%.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10902997A JPH10298723A (en) | 1997-04-25 | 1997-04-25 | Manufacture of aluminum alloy die casting |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP10902997A JPH10298723A (en) | 1997-04-25 | 1997-04-25 | Manufacture of aluminum alloy die casting |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH10298723A true JPH10298723A (en) | 1998-11-10 |
Family
ID=14499811
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP10902997A Pending JPH10298723A (en) | 1997-04-25 | 1997-04-25 | Manufacture of aluminum alloy die casting |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH10298723A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007162058A (en) * | 2005-12-13 | 2007-06-28 | Aisin Seiki Co Ltd | Method for manufacturing aluminum alloy member |
JP2011063830A (en) * | 2009-09-15 | 2011-03-31 | Hitachi Ltd | Aluminum die-cast product and method for modifying aluminum die-cast product |
JP2015203142A (en) * | 2014-04-15 | 2015-11-16 | 日産自動車株式会社 | Heat treatment method of aluminum alloy die casting member and aluminum alloy die casting member |
-
1997
- 1997-04-25 JP JP10902997A patent/JPH10298723A/en active Pending
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007162058A (en) * | 2005-12-13 | 2007-06-28 | Aisin Seiki Co Ltd | Method for manufacturing aluminum alloy member |
JP2011063830A (en) * | 2009-09-15 | 2011-03-31 | Hitachi Ltd | Aluminum die-cast product and method for modifying aluminum die-cast product |
JP2015203142A (en) * | 2014-04-15 | 2015-11-16 | 日産自動車株式会社 | Heat treatment method of aluminum alloy die casting member and aluminum alloy die casting member |
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