JP2004277756A - Aluminum alloy for fin by twin belt casting, and fin material - Google Patents
Aluminum alloy for fin by twin belt casting, and fin material Download PDFInfo
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【０００１】
【発明の属する技術分野】
本発明は、双ベルト鋳造用フィン用アルミニウム合金およびフィン材に関する。
【０００２】
【従来の技術】
車両にはフィンと通液管がろう付接合された各種のアルミニウム製熱交換器が装着されており、軽量化のために熱交換器を構成する各部材は年々薄肉化する傾向にある。そのため、薄肉でも十分な強度を維持できるように、ろう付後において高強度である部材が求められている。
【０００３】
また、フィン材は強度ばかりでなく耐エロージョン性も必要である。すなわち、標準的なろう付け温度は５９０〜６００℃であるが、実際のろう付温度が下方に外れるとろう付不良となるので、これを避けるために高めに設定する傾向がある。しかし、ろう付け温度が高めに外れると、Ａｌ−Ｓｉ系ろう材によって侵食されやすくなる。従って、ろう付け温度が高めに外れても、ろう材に侵食され難い良好な耐エロージョン性が望まれる。
【０００４】
従来、このような特性を持つフィン材は合金組成と製造方法の両面から検討されている。
【０００５】
例えば、特許文献１（ＷＯ ０１／５３５５３ Ａ１公報）の請求項１には、Ｆｅ：１．２〜２．４ｗｔ％、Ｓｉ：０．５〜１．１ｗｔ％、Ｍｎ：０．３〜０．６ｗｔ％およびＺｎ：０〜１．０ｗｔ％を含有するＡｌ合金を溶湯冷却速度を少なくとも３００℃／ｓｅｃ 以上で凝固させ、その後、圧延と熱処理を施して製造されるフィン材が開示されている。
【０００６】
また、特許文献２（特開２００２−２５６４０２号公報）には、Ｍｎ：０．３〜２．０ｗｔ％、Ｓｉ：０．５を超え１．５ｗｔ％以下、Ｆｅ：０．７〜２．０ｗｔ％を含有するＡｌ合金溶湯を鋳造時の冷却速度を１５〜１０００℃／ｓｅｃ で鋳造し、熱延、冷延して製造されるフィン材が開示されている。
【０００７】
【特許文献１】
ＷＯ ０１／５３５５３ Ａ１ 請求項１〜１２、第６頁上１〜９行。
【０００８】
【特許文献２】
特開２００２−２５６４０２ 請求項１、第６頁段落（００４１）、
第７頁第４〜５行。
【０００９】
【発明が解決しようとする課題】
連続鋳造（ＣＣ）はＤＣ鋳造と異なって鋳造スラブ厚さも薄く、ＤＣ鋳造の場合に必須の均熱処理やその後の厚さ１０ｍｍ程度までの熱延が省略できる等の生産上の利点があって、各種材料の製造に利用されている。
【００１０】
例えばＣＣ鋳造法には、相対峙する回転ロール間に溶湯を注湯し、強制冷却されているロール面で溶湯を急冷し、反注湯側より厚さの薄いスラブを連続的に取り出す双ロール鋳造法や、相対峙する回転ベルト間に溶湯を注湯し、強制冷却されているベルト面で溶湯を急冷し、反注湯側より厚さの薄いスラブを連続的に取り出す双ベルト鋳造法等が知られている。
【００１１】
前記特許文献１（ＷＯ ０１／５３５５３ Ａ１公報）記載の技術は、明細書の記載（第６頁上１〜９行）によれば、その鋳造方法は前記の双ロール鋳造法である。本発明者らの知見によれば、同公報請求項記載の上記合金組成範囲では、各元素含有量の上限値近傍域ではＦｅ，Ｓｉ，Ｍｎの含有量が多く固液共存範囲が広いために、双ロール鋳造法で鋳造するには高度なテクニックが必要である。これに対して、同公報第１０頁記載の実施例における組成は、Ｆｅ１．５２ｗｔ％、Ｍｎ０．３６ｗｔ％、Ｓｉ０．８３ｗｔ％、Ｚｎ０．４８ｗｔ％であって、上記合金組成範囲のうちでも元素含有量の少ない固液共存範囲の狭い範囲で試験をしている。またこのような実施例の組成では、ろう付後に高強度材（１４０ＭＰａ 以上）とならない。
【００１２】
前記特許文献２（特開２００２−２５６４０２号公報）記載の技術もまた、明細書の記載（第６頁段落００４１）によれば前記の双ロール鋳造法を挙げている。しかし、同公報第６頁記載の実施例では、双ロール鋳造法に替えて、第７頁第４〜５行に示されているように、幅：２００ｍｍ×長さ：５００ｍｍ×厚さ：７ｍｍの鋳型に鋳造している。また実施例記載の組成では、ろう付後に高導電率材（５０％ＩＡＣＳ以上）とならない。ここで、導電率は、フィン材の重要な性質である熱伝導率の指標である。
【００１３】
本発明の目的は、固液共存範囲が広くても容易に鋳造でき、ろう付後の強度と導電率が高く、しかも耐エロージョン性が高くろう付性に優れたフィン材の得られる双ベルト鋳造用フィン用アルミニウム合金と前記特性を有するフィン材を提供することである。
【００１４】
【課題を解決するための手段】
本発明者らは、双ベルト鋳造法は固液共存範囲が広くても容易に鋳造でき、しかも得られたフィン材は上記の諸特性を備えたものであるとの知見を得て、本発明を完成したものである。
【００１５】
即ち本発明は、Ｓｉ：０．７〜１．３ｗｔ％、Ｆｅ：２．０を超え２．８ｗｔ％以下、Ｍｎ：０．６を超え１．２ｗｔ％以下、およびＺｎ：０．０２ｗｔ％を超え１．５ｗｔ％以下を含有し、残部Ａｌおよび不可避的不純物からなることを特徴とする双ベルト鋳造用フィン用アルミニウム合金を提供する。元素含有量が多くても双ベルト鋳造法で容易に鋳造ができ、ろう付後の強度と導電率が高く、自然電位も低くしかもろう付性に優れたフィン材とすることができる。
【００１６】
更に結晶粒微細化剤を０．２ｗｔ％以下含有することにより、鋳造時の鋳造割れを防止できる。
【００１７】
また、本発明は、前記各組成からなり、最大径で０．１〜１．０μｍ以下の金属間化合物が１１万個／ｍｍ２ 以上存在し、ろう付後の結晶粒径が１５０μｍ以上であることを特徴とするアルミニウム合金フィン材をも提供する。このような化合物および結晶粒とすることで、フィン材は上記諸特性を備えることができる。
【００１８】
【発明の実施の形態】
本発明において採用する鋳造方法について説明する。
【００１９】
双ベルト鋳造法は、上下に対峙し水冷されている回転ベルト間に溶湯を注湯してベルト面からの冷却で溶湯を凝固させてスラブとし、ベルトの反注湯側より該スラブを連続して引き出してコイル状に巻き取る連続鋳造方法である。溶湯の凝固時の溶湯冷却速度は４０〜８０℃／ｓｅｃ （板厚の１／４位置）であることが好ましく、ベルト接触領域内でスラブ厚さ全体にわたって凝固が完了することが望ましい。得られるスラブの厚さは５〜８ｍｍであることが好ましく、この厚さであると板厚中央部の凝固速度も速く、均一組織でしかも本発明範囲の組成であると微細な化合物の多いおよびろう付後において結晶粒径の大きい優れた諸性質を有するフィン材とすることができる。
【００２０】
ＤＣ鋳造法は凝固時の溶湯冷却速度が遅く晶出物が粗大化して薄板圧延を妨げ、化合物数も８万個／ｍｍ２ 以下と少くなり、十分な粒子分散強化作用が得られないため、ろう付後の強度が低下する。
【００２１】
次にアルミニウム合金組成について説明する。
【００２２】
〔Ｓｉ：０．７〜１．３ｗｔ％〕
〔Ｆｅ：２．０ｗｔ％を超え２．８ｗｔ％以下〕
〔Ｍｎ：０．６ｗｔ％を超え１．２ｗｔ％以下〕
Ｓｉ，ＦｅおよびＭｎは、固溶強化と共に、Ａｌ−Ｆｅ，Ａｌ−（Ｆｅ，Ｍｎ）−Ｓｉ，Ａｌ−Ｍｎ系等の化合物粒子を晶出することにより分散強化の作用がある。また前記の条件で双ベルト鋳造し、冷間圧延して０．１ｍｍ以下、好ましくは０．０４〜０．０８ｍｍに圧延することによって晶出物が分断し、最大径で０．１〜１．０μｍの金属間化合物を１１万個／ｍｍ２ 以上存在させることができ、またろう付後の再結晶粒径を１５０μｍ以上とすることができる。
【００２３】
Ｓｉ含有量が下限値以下および／またはＭｎ含有量が下限値以下であると、固溶強化による強度の向上作用が得られない。Ｆｅ含有量が下限値以下であると前記の化合物条件が得られないため、晶出する化合物粒子数が減少し、ろう付後の分散粒子による強度の向上作用が得られない。Ｆｅ含有量の好ましい下限値は２．０７ｗｔ％である。
【００２４】
一方、Ｓｉ含有量が上限値を超えると、ろう材に対する耐エロージョン性が劣化し、導電率も低下する。Ｆｅ含有量が上限値を超えると晶出物が粗大化して薄板圧延を妨げ、Ｍｎ含有量が上限値を超えると導電率が低下する。
【００２５】
〔Ｚｎ：０．０２ｗｔ％を超え１．５ｗｔ％以下〕
Ｚｎは、フィン材の自然電位を卑に移行させ、アルミニウム製通液管と組み合わせた際に犠牲電極として作用することにより、通液管の耐食性を確保できる。
【００２６】
この犠牲電極作用を得るには、Ｚｎ含有量が０．０２ｗｔ％を超える必要がある。通常、フィン材にはＺｎを不可避的不純物として０．０２ｗｔ％以下含有しているので、犠牲電極作用による耐食性向上効果を顕在化させるには０．０２ｗｔ％を超えて含有させる。一方、Ｚｎ含有量が上限値を超えると導電率が低下してフィン材として好ましくない。好ましくは１．２ｗｔ％以下、更に好ましくは１．０ｗｔ％以下である。
【００２７】
〔ろう付後の結晶粒径：１５０μｍ以上〕
ろう付温度が高めに外れたときに問題となるエロージョンによるフィン溶けおよび座屈は、溶融ろうがフィン材の結晶粒界を侵食することにより生ずる。これを防ぐには、ろう材が溶融する直前の温度において、フィン材の結晶粒界の数を少なくする必要がある。具体的には、中間焼鈍後の最終冷延率を適宜選択してろう付後の結晶粒径を１５０μｍ以上とすることにより、これを達成できる。ろう付後の結晶粒径が１５０μｍより小さいと、フィン溶けおよび座屈の危険性が増大する。
【００２８】
〔結晶粒微細化剤：０．２ｗｔ％以下〕
結晶粒微細化剤を必要に応じて含有させると鋳造割れを確実に防止し、安定して鋳造することができる。結晶粒微細化剤としてはＴｉ，Ｂ等があり、Ｔｉの０．２ｗｔ％以下またはＴｉとＢの合計で０．２ｗｔ％以下含有させる。上限値を超えても顕著な効果の向上は得られない。
【００２９】
上記組成の他Ｃｕ，Ｍｇ，Ｃｒ，Ｎｉ，Ｇａ，Ｖ等が地金や返り材等から不可避的不純物として混入するが、各々０．２ｗｔ％以下、合計で０．３ｗｔ％以下までは本発明の効果を妨げないので許容できる。
【００３０】
以上説明した組成のアルミニウム合金溶湯を脱酸化物、除滓、鎮静等の溶湯処理を施した後、必要に応じてフィルターを通過させ、上記した条件で双ベルト鋳造し、得られたスラブを連続、または一旦コイルにしリコイルして圧延して薄板を得る。この薄板は焼鈍と圧延を施して０．１ｍｍ以下、好ましくは０．０４〜０．０８ｍｍに圧延して所定厚さのフィン材とする。
【００３１】
このようにして作製されたフィン材はアルミニウム製通液管と組み合わせてろう付される。ろう付けは公知の方法でよく、限定するものではないが、例えば弗化物系のフラックスを用いるろう付法が適している。この弗化物系のフラックスを用いる場合は、ろう材がクラッドされている通液管にベアのフィン材を組付けた後フラックスを塗布してろう付温度に加熱保持してろう付けする方法と、ベアの通液管に弗化物系のフラックス粉末と金属Ｓｉ粉末のスラリーを塗布し、ベアのフィン材を組付けてろう付温度に加熱保持して金属Ｓｉと通液管の極表面層とが反応してろう材を形成させてろう付けする方法等がある。
【００３２】
【実施例】
表１に示した各種組成の合金溶湯を溶製し、セラミックス製フィルターを通過させて双ベルト鋳造鋳型に注湯し、引出速度８メートル／分で厚さ７ｍｍのスラブを得た。溶湯の凝固時冷却速度は５０℃／ｓｅｃ であった。また、合金番号１の組成の合金溶湯については、引出速度６メートル／分での双ベルト鋳造も行い、厚さ７ｍｍのスラブを得た。このときの溶湯の凝固時冷却速度は７０℃／ｓｅｃ であった。該スラブは連続して巻き取ってコイルとし、このコイルを表２に示した厚さ（「中間焼鈍板厚」と表示）まで冷間圧延し、４００℃で焼鈍して軟化させた。その後更に冷延して厚さ０．０６ｍｍのフィン材とした。
【００３３】
得られたフィン材について、下記の測定および試験を行なった。
【００３４】
〔１〕圧延方向に平行な断面を走査型電子顕微鏡（反射電子像）で観察し、画像解析装置を用いて、各化合物の直径で最大の長さが０．１〜１．０μｍの範囲に入る金属間化合物の個数（個／ｍｍ２ ）を測定した。
【００３５】
〔２〕ろう付温度を想定して５９５〜６００℃×３分間加熱し、冷却後下記項目を測定した。
【００３６】
（１）引張強度（Ｎ／ｍｍ２ ）
（２）表面を電解研磨してバーカー法で結晶粒組織を現出後、切断法で圧延方向に平行な結晶粒径（μｍ）
（３）ＪＩＳ−Ｈ０５０５記載の導電率試験法で導電率（％ＩＡＣＳ）
（４）銀塩化銀電極を照合電極として、５％食塩水に６０分浸漬後の自然電位（ｍＶ）
〔３〕弗化物系のノコロック（Ｎｏｃｏｌｏｋ：登録商標）フラックスを使用（塗布量５〜７ｇ／ｍ２ ）し、ろう材クラッドアルミニウム通液管を想定して、厚さ０．２５ｍｍのブレージングシート（ろう材４０４５合金クラッド率８％）のろう材面上にコルゲート状に加工した前記フィン材を載置し、その上に厚さ１ｍｍの３００３合金片とダミーフィンと錘（合計１３２ｇ）を載せてろう付試験体とした。この試験体を６０５℃で５分保持し、冷却後ろう付断面を観察し、溶融ろうによって生じるフィン材結晶粒界のエロージョンが一部でもフィン材厚さを貫通したものは座屈する知見があるので耐エロージョン性不良（×印）とし、フィン材厚さまで達していなかったものを良（○印）とした。なお、コルゲート形状は、高さ２．３ｍｍ×幅２１ｍｍ×ピッチ３．４ｍｍとした。
【００３７】
上記の測定および試験の結果を表２に示す。
【００３８】
表２の結果から、本発明例（試料番号１，２，３，４および５）はろう付後の引張強度、導電率、自然電位および耐エロージョン性がバランスよく良好であるのに対して、組成範囲の外れている比較例（試料番号６，７，８，９，１０および１１）は、上記特性のいずれかが劣っていることが判る。
【００３９】
【表１】
【表２】
【発明の効果】
上述の如く本発明は、ろう付後の引張強度、導電率、自然電位およびろう材による耐エロージョン性が良好であるから、性能の良いろう付品が安定して得られる等の優れた効果のある発明である。なお、塩水噴霧試験による腐食減量が少なく、良好なフィン寿命を有する効果もある。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an aluminum alloy for a fin for twin belt casting and a fin material.
[0002]
[Prior art]
Vehicles are equipped with various aluminum heat exchangers in which fins and liquid passage pipes are brazed and joined, and the members constituting the heat exchanger tend to become thinner year by year for weight reduction. Therefore, a member having high strength after brazing is required so that sufficient strength can be maintained even with a thin wall.
[0003]
Further, the fin material needs not only strength but also erosion resistance. In other words, the standard brazing temperature is 590 to 600 ° C., but if the actual brazing temperature falls below, brazing failure will occur. Therefore, there is a tendency that the brazing temperature is set higher to avoid this. However, if the brazing temperature is too high, it is likely to be eroded by the Al-Si-based brazing material. Therefore, even if the brazing temperature is deviated to a high level, good erosion resistance which is hardly eroded by the brazing material is desired.
[0004]
Hitherto, fin materials having such characteristics have been studied from both the alloy composition and the manufacturing method.
[0005]
For example, in claim 1 of Patent Document 1 (WO 01/53553 A1), Fe: 1.2 to 2.4 wt%, Si: 0.5 to 1.1 wt%, Mn: 0.3 to 0. A fin material manufactured by solidifying an Al alloy containing 6 wt% and Zn: 0 to 1.0 wt% at a molten metal cooling rate of at least 300 ° C./sec, and then performing rolling and heat treatment is disclosed.
[0006]
Patent Document 2 (JP-A-2002-256402) discloses that Mn: 0.3 to 2.0 wt%, Si: more than 0.5 and 1.5 wt% or less, and Fe: 0.7 to 2.0 wt%. A fin material manufactured by casting a molten aluminum alloy containing 0.1% at a cooling rate of 15 to 1000 ° C./sec at the time of casting, hot rolling and cold rolling.
[0007]
[Patent Document 1]
WO 01/53553 A1 13. Lines 1 to 9 on page 6, 1 to 12.
[0008]
[Patent Document 2]
JP-A-2002-256402, Claim 1, page 6 paragraph (0041),
Page 7, lines 4-5.
[0009]
[Problems to be solved by the invention]
Continuous casting (CC) is different from DC casting in that the thickness of the casting slab is also thin, and there are advantages in production such as the necessity of soaking heat treatment and the subsequent hot rolling to a thickness of about 10 mm in the case of DC casting. Used in the manufacture of various materials.
[0010]
For example, in the CC casting method, a twin roll in which molten metal is poured between rotating rolls facing each other, the molten metal is rapidly cooled on a roll surface that is forcibly cooled, and a slab thinner than the anti-poured side is continuously taken out. Casting method or twin belt casting method in which molten metal is poured between rotating belts facing each other, the molten metal is quenched on the belt surface that has been forcibly cooled, and a slab thinner than the anti-pouring side is continuously removed. It has been known.
[0011]
According to the technology described in Patent Document 1 (WO 01/53553 A1), according to the description (1st to 9th lines on page 6), the casting method is the twin roll casting method. According to the findings of the present inventors, in the alloy composition range described in the same gazette, the contents of Fe, Si, and Mn are large and the solid-liquid coexistence range is wide near the upper limit of the content of each element. Advanced techniques are required for casting by twin roll casting. On the other hand, the composition in the example described on page 10 of the publication is 1.52 wt% of Fe, 0.36 wt% of Mn, 0.83 wt% of Si, and 0.48 wt% of Zn. The test is carried out in a small solid-liquid coexistence range. In addition, the composition of the embodiment does not become a high-strength material (140 MPa or more) after brazing.
[0012]
The technique described in Patent Document 2 (Japanese Patent Application Laid-Open No. 2002-256402) also mentions the twin-roll casting method according to the description (page 6, paragraph 0041). However, in the example described on page 6 of the publication, instead of the twin roll casting method, as shown on page 7, lines 4 to 5, the width: 200 mm × length: 500 mm × thickness: 7 mm Casting into a mold. Further, the composition described in the examples does not become a high conductivity material (50% IACS or more) after brazing. Here, the electrical conductivity is an index of the thermal conductivity, which is an important property of the fin material.
[0013]
An object of the present invention is to provide a twin-belt casting which can be easily cast even if the solid-liquid coexistence range is wide, has high strength and electrical conductivity after brazing, and has high erosion resistance and excellent brazing properties. An object of the present invention is to provide a fin aluminum alloy and a fin material having the above characteristics.
[0014]
[Means for Solving the Problems]
The present inventors have obtained the knowledge that the twin belt casting method can be easily cast even if the solid-liquid coexistence range is wide, and the obtained fin material has the above-mentioned various properties. Is completed.
[0015]
That is, in the present invention, Si: 0.7 to 1.3 wt%, Fe: more than 2.0 and 2.8 wt%, Mn: more than 0.6 and 1.2 wt%, and Zn: 0.02 wt% The present invention provides an aluminum alloy for twin belt casting fins, containing more than 1.5 wt% or less and the balance being Al and inevitable impurities. Even if the element content is large, casting can be easily performed by the twin belt casting method, and a fin material having high strength and electrical conductivity after brazing, a low natural potential, and excellent brazing properties can be obtained.
[0016]
Further, by containing the crystal grain refiner in an amount of 0.2 wt% or less, casting cracks during casting can be prevented.
[0017]
Further, the present invention is the result from the composition, there following the intermetallic compound 0.1~1.0μm 110,000 pieces / mm 2 or more in maximum diameter, the crystal grain size after brazing is at 150μm or more An aluminum alloy fin material characterized by the above feature is also provided. By using such compounds and crystal grains, the fin material can have the above-mentioned various properties.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
The casting method employed in the present invention will be described.
[0019]
In the twin belt casting method, molten metal is poured between rotating belts that are vertically opposed and water-cooled, and the molten metal is solidified by cooling from the belt surface to form a slab. This is a continuous casting method that draws out and winds it in a coil shape. The cooling rate of the molten metal during solidification is preferably 40 to 80 ° C./sec (１ ／ position of the plate thickness), and solidification is preferably completed over the entire slab thickness in the belt contact area. The thickness of the obtained slab is preferably 5 to 8 mm, and when the slab has this thickness, the solidification rate at the center of the plate thickness is high, and when the composition is within the range of the present invention, it has many fine compounds. After brazing, a fin material having a large crystal grain size and excellent properties can be obtained.
[0020]
In the DC casting method, the cooling rate of the molten metal at the time of solidification is slow, and the crystallized material is coarsened to hinder sheet rolling, and the number of compounds is reduced to 80,000 / mm 2 or less, and a sufficient particle dispersion strengthening effect cannot be obtained. The strength after brazing decreases.
[0021]
Next, the aluminum alloy composition will be described.
[0022]
[Si: 0.7 to 1.3 wt%]
[Fe: more than 2.0 wt% and 2.8 wt% or less]
[Mn: more than 0.6 wt% and 1.2 wt% or less]
Si, Fe and Mn have the effect of strengthening dispersion by crystallizing compound particles such as Al-Fe, Al- (Fe, Mn) -Si, and Al-Mn, together with solid solution strengthening. Further, under the above conditions, twin belt casting, cold rolling, and rolling to 0.1 mm or less, preferably 0.04 to 0.08 mm separate crystallized substances, and the maximum diameter is 0.1 to 1. The intermetallic compound of 0 μm can be present in an amount of 110,000 / mm 2 or more, and the recrystallized particle size after brazing can be made 150 μm or more.
[0023]
When the Si content is equal to or less than the lower limit and / or the Mn content is equal to or less than the lower limit, the effect of improving strength by solid solution strengthening cannot be obtained. If the Fe content is less than the lower limit, the above-mentioned compound conditions cannot be obtained, so that the number of compound particles to be crystallized decreases, and the effect of improving the strength by the dispersed particles after brazing cannot be obtained. A preferred lower limit of the Fe content is 2.07 wt%.
[0024]
On the other hand, when the Si content exceeds the upper limit, the erosion resistance to the brazing material is deteriorated, and the conductivity is also reduced. If the Fe content exceeds the upper limit, the crystallized material becomes coarse and hinders sheet rolling, and if the Mn content exceeds the upper limit, the electrical conductivity decreases.
[0025]
[Zn: more than 0.02 wt% and 1.5 wt% or less]
Zn shifts the natural potential of the fin material to a low value and acts as a sacrificial electrode when combined with an aluminum liquid passage tube, thereby ensuring the corrosion resistance of the liquid passage tube.
[0026]
To obtain this sacrificial electrode function, the Zn content needs to exceed 0.02 wt%. Usually, the fin material contains 0.02 wt% or less of Zn as an unavoidable impurity. Therefore, in order to make the corrosion resistance improving effect by the sacrificial electrode effect apparent, Zn is added in excess of 0.02 wt%. On the other hand, when the Zn content exceeds the upper limit, the conductivity is lowered, which is not preferable as a fin material. It is preferably at most 1.2 wt%, more preferably at most 1.0 wt%.
[0027]
[Crystal grain size after brazing: 150 µm or more]
Melting and buckling of the fins due to erosion, which are problematic when the brazing temperature is too high, are caused by the molten braze eroding the grain boundaries of the fin material. To prevent this, it is necessary to reduce the number of crystal grain boundaries of the fin material at a temperature immediately before the brazing material melts. Specifically, this can be achieved by appropriately selecting the final cold rolling ratio after the intermediate annealing and setting the crystal grain size after brazing to 150 μm or more. If the crystal grain size after brazing is smaller than 150 μm, the risk of fin melting and buckling increases.
[0028]
[Grain refiner: 0.2 wt% or less]
When a crystal grain refiner is contained as required, casting cracks can be reliably prevented, and casting can be performed stably. Examples of the crystal grain refiner include Ti, B, and the like. The content is 0.2 wt% or less of Ti or 0.2 wt% or less in total of Ti and B. Even if it exceeds the upper limit, no remarkable improvement in effect is obtained.
[0029]
In addition to the above composition, Cu, Mg, Cr, Ni, Ga, V and the like are mixed as unavoidable impurities from the base metal and the return material, etc., respectively. Is acceptable because it does not hinder the effect of
[0030]
After subjecting the molten aluminum alloy having the composition described above to deoxidation, slagging, calming, etc., it is allowed to pass through a filter as necessary, and is subjected to twin belt casting under the above conditions, and the obtained slab is continuously cast. Or, it is once coiled and recoiled and rolled to obtain a thin plate. This thin plate is annealed and rolled to 0.1 mm or less, preferably 0.04 to 0.08 mm, to obtain a fin material having a predetermined thickness.
[0031]
The fin material thus produced is brazed in combination with an aluminum flow pipe. The brazing may be performed by a known method, and is not limited. For example, a brazing method using a fluoride-based flux is suitable. When using this fluoride-based flux, a method of brazing by applying a flux after assembling a bare fin material to a flow pipe in which a brazing material is clad, heating and maintaining the brazing temperature, A slurry of a fluoride-based flux powder and a metal Si powder is applied to the flow pipe of the bare, and the fin material of the bare is assembled and heated and maintained at a brazing temperature, so that the metal Si and the extreme surface layer of the flow pipe are formed. There is a method of forming a brazing material by reacting and brazing.
[0032]
【Example】
Molten alloys of various compositions shown in Table 1 were melted, passed through a ceramic filter, and poured into a twin-belt casting mold to obtain a slab having a thickness of 7 mm at a drawing speed of 8 m / min. The cooling rate during solidification of the molten metal was 50 ° C./sec. Further, with respect to the molten alloy having the composition of alloy number 1, twin belt casting was performed at a drawing speed of 6 m / min to obtain a slab having a thickness of 7 mm. At this time, the cooling rate during solidification of the molten metal was 70 ° C./sec. The slab was continuously wound into a coil, and the coil was cold-rolled to a thickness shown in Table 2 (indicated as “intermediate annealed plate thickness”) and annealed at 400 ° C. to soften. Thereafter, it was further cold-rolled to obtain a fin material having a thickness of 0.06 mm.
[0033]
The following measurements and tests were performed on the obtained fin material.
[0034]
[1] Observe the cross section parallel to the rolling direction with a scanning electron microscope (backscattered electron image), and use an image analyzer to set the maximum length in the range of 0.1 to 1.0 μm in diameter of each compound. The number (pieces / mm 2 ) of the intermetallic compound that entered was measured.
[0035]
[2] Assuming the brazing temperature, heating was performed at 595 to 600 ° C. for 3 minutes, and after cooling, the following items were measured.
[0036]
(1) Tensile strength (N / mm 2 )
(2) After the surface is electrolytically polished to reveal a crystal grain structure by a Barker method, a crystal grain size (μm) parallel to a rolling direction is obtained by a cutting method.
(3) Conductivity (% IACS) by the conductivity test method described in JIS-H0505
(4) Spontaneous potential (mV) after immersion in a 5% saline solution for 60 minutes using a silver-silver chloride electrode as a reference electrode
[3] A brazing sheet having a thickness of 0.25 mm, using a fluoride-based Nocolok (registered trademark) flux (application amount: 5 to 7 g / m 2 ) and assuming a brazing material-clad aluminum flow pipe. The fin material processed into a corrugated shape is placed on the brazing material surface having a brazing material 4045 alloy cladding ratio of 8%), and a 3003 alloy piece having a thickness of 1 mm, a dummy fin, and a weight (132 g in total) are placed thereon. A brazing specimen was used. The specimen was held at 605 ° C. for 5 minutes, and after cooling, the brazing cross section was observed, and it was found that the erosion of the fin material crystal grain boundaries caused by the molten solder partially penetrated the fin material thickness, causing buckling. Therefore, the erosion resistance was poor (marked by x), and the one that did not reach the fin material thickness was evaluated as good (marked by ○). The corrugated shape was 2.3 mm in height × 21 mm in width × 3.4 mm in pitch.
[0037]
Table 2 shows the results of the above measurements and tests.
[0038]
From the results shown in Table 2, the inventive examples (Sample Nos. 1, 2, 3, 4 and 5) had good balance in tensile strength, electrical conductivity, natural potential and erosion resistance after brazing. It can be seen that the comparative examples (sample numbers 6, 7, 8, 9, 10, and 11) out of the composition range are inferior in any of the above characteristics.
[0039]
[Table 1]
[Table 2]
【The invention's effect】
As described above, since the present invention has good tensile strength after brazing, electrical conductivity, natural potential and erosion resistance due to brazing material, excellent effects such as stably obtaining a brazed product having high performance can be obtained. An invention. In addition, there is an effect that the corrosion weight loss by the salt spray test is small and a good fin life is provided.
Claims (4)
Ｓｉ：０．７〜１．３ｗｔ％、
Ｆｅ：２．０ｗｔ％を超え２．８ｗｔ％以下、
Ｍｎ：０．６ｗｔ％を超え１．２ｗｔ％以下、
Ｚｎ：０．０２ｗｔ％を超え１．５ｗｔ％以下、および
残部：Ａｌおよび不可避的不純物
から成ることを特徴とする双ベルト鋳造用フィン用アルミニウム合金。The following composition:
Si: 0.7-1.3 wt%,
Fe: more than 2.0 wt% and not more than 2.8 wt%,
Mn: more than 0.6 wt% and 1.2 wt% or less,
Zn: an aluminum alloy for fins for twin belt casting, characterized by comprising more than 0.02 wt% and not more than 1.5 wt% and the balance: Al and unavoidable impurities.
Ｓｉ：０．７〜１．３ｗｔ％、
Ｆｅ：２．０ｗｔ％を超え２．８ｗｔ％以下、
Ｍｎ：０．６ｗｔ％を超え１．２ｗｔ％以下、
Ｚｎ：０．０２ｗｔ％を超え１．５ｗｔ％以下、および
残部：Ａｌおよび不可避的不純物
から成り、最大径で０．１〜１．０μｍの金属間化合物が１１万個／ｍｍ２ 以上存在し、ろう付後の結晶粒径が１５０μｍ以上であることを特徴とするアルミニウム合金フィン材。The following composition:
Si: 0.7-1.3 wt%,
Fe: more than 2.0 wt% and not more than 2.8 wt%,
Mn: more than 0.6 wt% and 1.2 wt% or less,
Zn: more than 0.02 wt% and 1.5 wt% or less, and the balance: Al and an unavoidable impurity, at least 110,000 intermetallic compounds having a maximum diameter of 0.1 to 1.0 μm / mm 2 , An aluminum alloy fin material having a crystal grain size of 150 μm or more after brazing.
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Cited By (6)
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|---|---|---|---|---|
| JP2006176850A (en) * | 2004-12-24 | 2006-07-06 | Mitsubishi Alum Co Ltd | High-strength aluminum alloy fin material for heat exchanger having excellent erosion resistance, and heat exchanger |
| JP2007517986A (en) * | 2004-01-12 | 2007-07-05 | アルコア インコーポレイテッド | Highly conductive finstock alloy, manufacturing method and resulting product |
| JP2009162450A (en) * | 2008-01-09 | 2009-07-23 | Sumitomo Light Metal Ind Ltd | Aluminum heat exchanger and its manufacturing method |
| US10280495B2 (en) | 2012-08-30 | 2019-05-07 | Denso Corporation | High-strength aluminum alloy fin material and production method thereof |
| CN112439879A (en) * | 2020-11-12 | 2021-03-05 | 成都阳光铝制品有限公司 | Production process of aluminum profile for automobile battery end plate |
| CN114871418A (en) * | 2015-09-10 | 2022-08-09 | 南线有限责任公司 | Ultrasonic grain refinement and degassing procedure and system for metal casting |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007517986A (en) * | 2004-01-12 | 2007-07-05 | アルコア インコーポレイテッド | Highly conductive finstock alloy, manufacturing method and resulting product |
| JP2006176850A (en) * | 2004-12-24 | 2006-07-06 | Mitsubishi Alum Co Ltd | High-strength aluminum alloy fin material for heat exchanger having excellent erosion resistance, and heat exchanger |
| JP4566729B2 (en) * | 2004-12-24 | 2010-10-20 | 三菱アルミニウム株式会社 | High strength aluminum alloy fin material and heat exchanger for heat exchanger with excellent erosion resistance |
| JP2009162450A (en) * | 2008-01-09 | 2009-07-23 | Sumitomo Light Metal Ind Ltd | Aluminum heat exchanger and its manufacturing method |
| US10280495B2 (en) | 2012-08-30 | 2019-05-07 | Denso Corporation | High-strength aluminum alloy fin material and production method thereof |
| DE112013004245B4 (en) | 2012-08-30 | 2024-01-04 | Denso Corporation | High strength aluminum alloy fin material and manufacturing method thereof |
| CN114871418A (en) * | 2015-09-10 | 2022-08-09 | 南线有限责任公司 | Ultrasonic grain refinement and degassing procedure and system for metal casting |
| CN112439879A (en) * | 2020-11-12 | 2021-03-05 | 成都阳光铝制品有限公司 | Production process of aluminum profile for automobile battery end plate |
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