JP3966680B2

JP3966680B2 - Method for adjusting particle content of particle-dispersed Al alloy casting using return material with unknown particle content

Info

Publication number: JP3966680B2
Application number: JP2000284797A
Authority: JP
Inventors: 泰上田; 勝利宮元
Original assignee: Kurimoto Ltd
Current assignee: Kurimoto Ltd
Priority date: 2000-09-20
Filing date: 2000-09-20
Publication date: 2007-08-29
Anticipated expiration: 2020-09-20
Also published as: JP2002096154A

Description

【０００１】
【発明の属する技術分野】
本発明は粒子分散型のＡｌ合金鋳物の製造方法、特に含有率の不明な分散粒子を含むリターン材を使用した溶湯の分散粒子含有率の調整技術に係る。
【０００２】
【従来の技術】
Ａｌ合金鋳物は鉄、鋼鋳物に比べて同形状、同一サイズでも格段に軽く、自動車用、産業車両、鉄道用をはじめ電気、通信機器、日用品など広く用いられている。近来はたとえばＡｌ−Ｃｕ系、Ａｌ−Ｍｇ系、Ａｌ−Ｓｉ系などを基本とするＡｌ合金に、さらにセラミックスなどを配合した複合材として特定の性質を一層強化して、特定の目的に供する開発も進んでいる。
【０００３】
複合Ａｌ合金鋳物には、セラミックスなどの成形体（一般にはプリフォームと呼ばれる）をＡｌ合金溶湯に含浸させた繊維強化型Ａｌ合金鋳物や、セラミックスなどの粒子をＡｌ合金溶湯内に均一に分散して強化した粒子分散型Ａｌ合金鋳物がある。通常、繊維強化型Ａｌ合金鋳物は、個別に用意されたプリフォーム及びＡｌによって、あらかじめその複合化率は決定されて鋳造される。また、粒子分散型Ａｌ合金鋳物は、予めＡｌ合金中に一定量の粒子（例えば、セラミックス粒子など）が調整された原料を溶湯化して粒子を均一分散させて鋳造するか、若しくは個別に用意されたＡｌ合金溶湯に一定量の粒子を添加して製造する。粒子分散型Ａｌ合金鋳物の製造方法としては、２種のセラミックス粒子を均一分散させる方法を開示した特開平４-２９７５３５号や粒子を最適分散させる装置及び方法を開示した特開平７-９０４２３号などがあるが、これらの方法はＡｌ合金に一定の複合材を混入・分散させ、目的物たる完成品を製造することを主たる目的としたものである。
【０００４】
粒子分散型Ａｌ合金鋳物の一例として自動車や鉄道車両のブレーキディスクへの適用がある。従来の鋳鉄材に代わり高速化が一段と進むＪＲ新幹線用の車両などは、摩擦特性のさらなる向上と車両の軽量化という命題に応えるべくＡｌ合金鋳物への材質転換が指向され、摩擦特性の一段の強化を目指してＡｌベースの母合金にセラミックスを均等に分散強化する開発が進められている。特開平３-４７９４５号のようにＡｌ−Ｍｇ合金にＡｌ₂Ｏ₃粒子またはＳｉＣ粒子を分散した、また特開平５-２７９７７０号のようにＡｌ−Ｓｉ合金にＳｉＣ粒子を５〜３０％均等に分散したブレーキディスクを提起するなど、特定の部材に要求される特性を強化する有効な手段としては注目を集める分野となっている。
【０００５】
ところでＡｌ合金溶湯中へ特定の分散粒子を添加する工程は、双方の溶融点の差、比重差、イオン化傾向、濡れ性など複雑な反応要素が絡み合って物理的、化学的に特有の技術的困難性を伴ない、分散粒子自体の事前の製造と、これに適合したＡｌ合金成分、その添加手法と特定の装置など一貫した管理体制の下に関連付けて進めることが望ましく、現在ではＡｌ合金原料メーカーが特殊な技法を駆使してＡｌ母合金に一定含有率のＳｉＣ粒子をあらかじめ分散した粒子分散型Ａｌ合金のインゴットを製造し、これを鋳物メーカに提供するという分業体制を敷くことが経済的にも品質上にも最も合理的な方法であるとされている。
【０００６】
【発明が解決しようとする課題】
鋳物メーカが鋳造品を製作する場合には、溶解原料として新規購入の粒子分散型Ａｌ合金インゴットの他、耐用限度を使い切った製品の戻り、不良品、鋳造時の湯口、湯道、押湯などがリターン材として循環再使用される点は材質を問わず共通する。しかしながら粒子分散型Ａｌ合金鋳物について言えば、鋳造工程においては溶解中にＡｌの酸化減耗があり、不良品の中にも粒子含有率の過不足が不良原因となった場合もあって、さまざまの粒子含有率の異なるリターン材を一つの炉にまとめて再溶解するのであるから、果たして所望の含有率で粒子が分散した鋳物を鋳造できるのか甚だ疑問である。
【０００７】
粒子分散型Ａｌ合金鋳物製のブレーキディスクを高速車両に適用するためには、摩擦係数の定常化という分散粒子による強化作用が重要な前提であり、かつ、その品質管理上の数値的基準としては当然分散粒子の含有率が主体となる。従ってＡｌと粒子の定率関係が前記のように事前に確定することが不可能なリターン材を使用すれば、現実の粒子含有率が不明な溶湯をそのまま鋳造せざるを得ず、品質の保証上、到底許されないことである。しかも一方では、リターン材のリサイクルは、資源の確保や経済性の点からも絶対避けては通れない社会的要請でもある。
【０００８】
本発明は以上の課題を解決するため、正確な粒子含有率が不明な各所発生のリターン材を使用して鋳造するに当たり、所望の粒子含有率を維持できるように炉前で簡単迅速に調整するようにした粒子分散型Ａｌ合金鋳物の製造方法を提供することが目的である。
【０００９】
【課題を解決するための手段】
本発明に係る粒子分散型Ａｌ合金鋳物の粒子含有率調整方法は、溶解原料のすべて、または少なくとも一部に粒子含有率不明の分散粒子を含むリターン材を使用して溶解し、溶解した溶湯を撹拌して分散粒子を均等に拡散した後にその比重を測定し、あらかじめ作成した該粒子分散型Ａｌ合金特有の比重と粒子含有率の回帰式に当てはめて現在の粒子含有率、および目標粒子含有率との乖離を検知し、前記溶湯を保温したまま静置して比重差によって分散粒子を母材のＡｌ合金溶湯から分離沈降させた後、上層のＡｌ合金溶湯から算出した所望量だけ汲み出し除去して目標の粒子含有率と一致するように濃縮するか、新たにＡｌ合金材を所望量加えて分散粒子の目標粒子含有率と一致するように稀釈し、再度、前記溶湯を前記粒子が均等に分散するように撹拌した後、鋳型へ注湯する手順によって前記の課題を解決した。
【００１０】
また、より具体的には前記粒子含有率調整方法において、比重の測定はアルキメデス法により、また粒子含有率の測定は試料のミクロ組織をコンピューターによる画像解析法に基づいて前記回帰式を作成することが好ましい実施形態であり、さらにＡｌ合金がＡｌ−Ｓｉ系合金であり、分散粒子がＳｉＣであることが望ましい。なお、この場合においては、比重と粒子含有率の回帰式は、
ＳｉＣ＝｛（１．７３±α）×比重−（４．６０±β）｝×１００
で示される。
但し、α及びβはＡｌ合金の比重、及び分散粒子の比重によって決まる定数。
【００１１】
【発明の実施の形態】
実操業に入る前に種々の粒子含有率と比重との関係を組み合わせて当該Ａｌ合金と分散粒子に適合できる回帰式を作成する手順を先行する。即ち、さまざまな含有率の分散粒子を含むリターン材１００％の溶解原料を溶落ち後、該溶湯を十分に撹拌して含有する粒子を完全に均等に分散させた後、該溶湯の一部を試料として採取して比重とミクロ組織を検査する。
【００１２】
具体的には、比重Ｓはアルキメデス法に従い、試料の大気中の重量Ｗ1、ヒモ重量Ｗ2、水中の重量（ヒモ付き）Ｗ3、を測定して次式で計算する。
Ｓ＝Ｗ1／｛Ｗ1−（Ｗ3−Ｗ2）｝
ミクロ組織は顕微鏡下の視野でＡｌが白い領域として、ＳｉＣが黒い斑点として顕れるから、全領域に占める黒色部分の面積％をコンピュータによる画像処理によってＳｉＣの含有率として特定する。
【００１３】
引き続いて前記溶湯に分散粒子を含まないＡｌ合金材、または近似的には純Ａｌを添加して分散粒子を希釈し、撹拌、均等化の後に再び試料を採取して同様に比重とＳｉＣ含有率との相関データを採る。この作業を繰り返してその都度、比重〜ＳｉＣ含有率を検知する。図２、図３はこの検定手順の一例を示した画像であり、白地がＡｌ、黒部がＳｉＣの存在を表わし、図２は比重が２．７６の試料の組織がＳｉＣ：１６．３０％、図３は比重が２.７９の試料の組織がＳｉＣ：２３．１０％と画像処理によって算定された例である。図１はこのように比重とＳｉＣ含有率のデータをプロットし、さらにこの相関を最小二乗法による近似線で代表した線図とし、この近似線を中心として実験上のバラツキを吸収した一次関数の回帰式で示すと、
ＳｉC＝｛（１．７３±α）×比重−（４．６０±β）｝×１００（数式１）で示される。但し、α及びβはＡｌ−Ｓｉ合金の比重、及び分散粒子の比重によって決まる定数であり、中心の近似線においてはα、βが共に０である。
この実施例の場合には前記の線図のバラツキを吸収する数式として経験的には、ＳｉC＝｛（１．７３±０．５）×比重−（４．６０±１．５）｝×１００（数式２）
で特定される。（図１の斜線範囲）
【００１４】
前記回帰式および近似式が作成された後、実操業に入る。少なくとも一部にリターン材を使用した未知の含有率の分散粒子を含む溶解材料は、溶落ち後、撹拌して含有する分散粒子を均等に分散した上で試料を採取する。試料の比重を測定すれば前記図１の線図、または数式化した回帰式（たとえば前記数式２）に当てはめて現在の粒子含有率を検知して調整のベース値とする。
【００１５】
粒子含有率の調整としては、このベース値から計算して粒子含有率の不足するときは粒子を追加し、粒子含有率が過大であるときはＡｌ合金材または純Ａｌ材を追加して稀釈する方法もあるが、先に述べたように粒子の新たな添加は原料メーカの特殊な技術に依存せざるを得ず、鋳物メーカの溶解作業中に組込むことは品質上、必ずしも適当ではないから、Ａｌ合金材または純Ａｌ材の新たな追加による稀釈、または溶融Ａｌ合金のみを除去して濃縮することにより、粒子含有率を調整する方法が最も合理的である。溶融Ａｌ合金のみを除去するためには、撹拌によって一旦、均等に分散した分散粒子を比重差によって下方へ沈降分離するように温度を保持したまま一定時間鎮静する必要がある。一定時間は母合金の性質、分散粒子の含有率や材質によって経験的に知得する。鎮静した上方のＡｌ合金溶湯から必要量だけ汲み出して分散粒子含有率を目標値まで上げる。なお、図４は鎮静状態を確認するために採取した試験片のミクロ組織であり、黒部で表れるＳｉＣ粒子がほとんど存在せず、ほぼ完全なＡｌ合金単体の状態に分離していることを示している。
【００１６】
本発明の実施形態として、リターン材１００％を再溶解した溶解Ａと、インゴットとリターン材を組み合わせて配合し溶解した溶解Ｂのケースを表１に基づいて説明する。
なお、前記インゴット（母合金）はＡｌ−Ｓｉ系合金、分散粒子としてはＳｉＣを適用し、基準粒子含有率は２０％、比重は２．７７の粒子分散型Ａｌ合金インゴットを使用した。
【００１７】
【表１】
表１

【００１８】
表１において、両溶解Ａ、Ｂともこれらの原料を溶解し、溶落ち後試料ＴＰ１を採取する。この試料ＴＰ１は参考値程度であり、図示しない公知の撹拌装置にて直ちに溶湯を十分撹拌して含有する粒子が均等に溶湯内に分散した後、該溶湯から試料ＴＰ２を採取し、溶湯全体の比重とミクロ組織とを検査する。
この撹拌の際に付加的に、Ａｒガスを吹き込んでバブリングし、溶湯中に含まれる酸化物、ごみなどの不純物を除去する。
この均等分散状態の比重測定値を数式２に当てはめてＳｉＣ含有率を検知し、目標粒子含有率に達するためのＡｌ合金溶湯の汲み出し量または追加量を算出する。
【００１９】
汲み出すＡｌ合金溶湯は粒子を含まない純粋な母合金に近いほど正確さが保てるから、試料ＴＰ２を採取後、比重差によってＳｉＣ粒子が沈降するまで静置する時間が必要で、経験的に決定する。ＳｉＣ粒子が十分沈降分離した後、上層のＡｌ合金から所望量の上澄み液を汲み出して粒子濃度を濃縮し、または粒子を含まないＡｌ合金材（インゴット）若しくは近似的に純Ａｌ材を追加して粒子濃度を稀釈し、調整が終われば再び溶湯を撹拌しＳｉＣ粒子を全体に均等分散させ、確認用に試料ＴＰ３を採取すると共に鋳造を開始する。表１の右欄には各手順毎に採取した試料ＴＰ１、ＴＰ２、ＴＰ３の比重と、数式から算出されたＳｉＣ含有率の変遷をまとめたものであり、測定誤差などを考慮に入れると両ケースとも目標であるＳｉＣ含有率２０％をほぼ満足する範囲に調整されている。
【００２０】
【発明の効果】
本発明は以上に述べた通り、粒子分散によって特定の性質を強化したＡｌ合金鋳物を製造するに当って、鋳造上、不可避となるリターン材のリサイクルを、品質を完全に保証した上で容易に実施する現実的な方法を提供したから、鋳造技術上の難点を解消し、目的とする粒子分散作用を確実に具現化する効果がある。今後、高速運動を担持する部材の軽量化は世界的な趨勢であり、粒子分散型Ａｌ合金鋳物はますます広い分野で多くの種類に適用されることが必須の傾向であるから、その分野の発展をバックアップする素材技術の一環として貴重な役割を果す効果が予見される。
【図面の簡単な説明】
【図１】本発明の実施形態を示す比重〜ＳｉＣ含有率の相関図である。
【図２】同じ相関図のベースとなる試料の顕微鏡組織を画像処理した解析図（Ａ）とその拡大図（Ｂ）である。
【図３】同じ相関図のベースとなる別の粒子含有率の試料における顕微鏡組織を画像処理した解析図（Ａ）とその拡大図（Ｂ）である。
【図４】本発明の実施形態において鎮静、粒子分離後のＡｌ合金試料の顕微鏡組織を画像処理した解析図（Ａ）とその拡大図（Ｂ）である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a particle-dispersed Al alloy casting, and more particularly to a technique for adjusting the content of dispersed particles in a molten metal using a return material containing dispersed particles whose content is unknown.
[0002]
[Prior art]
Al alloy castings are much lighter in shape and size than iron and steel castings, and are widely used in automobiles, industrial vehicles, railways, as well as electrical, communication equipment, and daily necessities. Recently, for example, Al-Cu-based, Al-Mg-based, Al-Si-based Al alloys are further developed as composite materials containing ceramics, etc., to further strengthen specific properties and serve specific purposes. Is also progressing.
[0003]
In composite Al alloy castings, fiber reinforced Al alloy castings in which a molded body such as ceramics (generally called a preform) is impregnated in molten Al alloy, or particles of ceramics are uniformly dispersed in the molten Al alloy. There is a particle-dispersed Al alloy casting that has been reinforced. Usually, a fiber-reinforced Al alloy casting is cast with a composite rate determined beforehand by a preform and Al prepared individually. Also, the particle-dispersed Al alloy casting is prepared by melting a raw material in which a certain amount of particles (for example, ceramic particles) is previously adjusted in an Al alloy and then uniformly dispersing the particles or casting them. A certain amount of particles are added to the molten Al alloy. As a method for producing a particle-dispersed Al alloy casting, Japanese Patent Application Laid-Open No. 4-297535 which discloses a method for uniformly dispersing two kinds of ceramic particles, Japanese Patent Application Laid-Open No. 7-90423 which discloses an apparatus and method for optimally dispersing particles, and the like. However, these methods are mainly intended to produce a finished product as a target object by mixing and dispersing a certain composite material in an Al alloy.
[0004]
As an example of the particle-dispersed Al alloy casting, there is application to a brake disk of an automobile or a railway vehicle. JR Shinkansen vehicles, etc., where speed increases further in place of conventional cast iron materials, are directed to changing to Al alloy castings to meet the proposition of further improving friction characteristics and reducing vehicle weight. Aiming at strengthening, development is under way to uniformly disperse and strengthen ceramics in an Al-based master alloy. As disclosed in JP-A-3-47945, Al ₂ O ₃ particles or SiC particles are dispersed in an Al—Mg alloy. Also, as disclosed in JP-A-5-279770, 5-30% of SiC particles are evenly distributed in the Al—Si alloy. As an effective means for strengthening the characteristics required for a specific member, such as providing dispersed brake discs, it has become a field of attention.
[0005]
By the way, the process of adding specific dispersed particles into the molten Al alloy is a technical difficulty that is physically and chemically unique due to intricate reaction elements such as differences in melting point, difference in specific gravity, ionization tendency, and wettability. It is desirable to proceed in advance under a consistent management system such as pre-production of dispersed particles themselves, Al alloy components suitable for this, addition method and specific equipment, etc. However, it is economical to create a divisional labor system that uses a special technique to produce a particle-dispersed Al alloy ingot in which SiC particles of a certain content are pre-dispersed in an Al mother alloy and provide this to casting manufacturers. It is said that it is the most reasonable method in terms of quality.
[0006]
[Problems to be solved by the invention]
When casting manufacturers produce cast products, in addition to newly purchased particle-dispersed Al alloy ingots as melting raw materials, return of products that have used up their service life, defective products, pouring gates, runners, feeders, etc. Is the same regardless of the material used. However, in the case of particle-dispersed Al alloy castings, there is a variety of problems in the casting process, in which there is oxidative depletion of Al during melting, and defective products may be caused by excessive or insufficient particle content. Since return materials having different particle contents are collectively remelted in one furnace, it is doubtful whether a casting in which particles are dispersed at a desired content can be cast.
[0007]
In order to apply brake discs made of particle-dispersed Al alloy castings to high-speed vehicles, the strengthening action by dispersed particles, that is, to stabilize the friction coefficient, is an important premise, and as a numerical standard for its quality control Of course, the content of dispersed particles is the main component. Therefore, if a return material in which the constant rate relationship between Al and particles cannot be determined in advance as described above is used, a molten metal whose actual particle content is unknown must be cast as it is, for quality assurance. This is unacceptable. On the other hand, recycling of return materials is a social requirement that cannot be avoided from the viewpoint of securing resources and economy.
[0008]
In order to solve the above problems, the present invention adjusts easily and quickly in front of the furnace so that the desired particle content can be maintained when casting using a return material generated in various places where the exact particle content is unknown. It is an object to provide a method for producing such a particle-dispersed Al alloy casting.
[0009]
[Means for Solving the Problems]
The method for adjusting the particle content of the particle-dispersed Al alloy casting according to the present invention is obtained by using a return material containing dispersed particles whose particle content is unknown in all or at least a part of the melting raw material. After the dispersion particles are uniformly diffused by stirring, the specific gravity is measured, and applied to the regression equation of the specific gravity and particle content specific to the particle-dispersed Al alloy prepared in advance, and the current particle content and target particle content The molten metal is allowed to stand still while being kept warm, and the dispersed particles are separated and settled from the Al alloy molten metal by the specific gravity difference, and then pumped out and removed by a desired amount calculated from the upper Al alloy molten metal. Concentrate to match the target particle content, or add a new amount of Al alloy material and dilute to match the target particle content of the dispersed particles. Min After stirring to solved the above problems by procedures pouring into the mold.
[0010]
More specifically, in the method for adjusting the particle content , the specific gravity is measured by the Archimedes method, and the particle content is measured by preparing the regression equation based on a computerized image analysis method of the sample microstructure. Is a preferred embodiment, and it is further desirable that the Al alloy is an Al—Si based alloy and the dispersed particles are SiC. In this case, the regression equation of specific gravity and particle content is
SiC = {(1.73 ± α) × specific gravity− (4.60 ± β)} × 100
Indicated by
However, α and β are constants determined by the specific gravity of the Al alloy and the specific gravity of the dispersed particles.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Prior to the start of actual operation, a procedure for preparing a regression equation that can be adapted to the Al alloy and dispersed particles by combining the relationship between various particle contents and specific gravity is preceded. That is, after 100% of the raw material of the return material containing dispersed particles having various contents is melted down, the molten metal is sufficiently agitated to completely and uniformly disperse the contained particles. Samples are taken and examined for specific gravity and microstructure.
[0012]
Specifically, the specific gravity S is calculated according to the Archimedes method by measuring the weight W1 of the sample in the atmosphere, the weight W2 of the string, and the weight W3 (with string) W3 in the water.
S = W1 / {W1- (W3-W2)}
In the microstructure, Al appears as a white area in the visual field under the microscope, and SiC appears as black spots. Therefore, the area percentage of the black portion in the entire area is specified as the SiC content by computer image processing.
[0013]
Subsequently, an Al alloy material that does not contain dispersed particles in the molten metal, or approximately pure Al is added to dilute the dispersed particles, and after stirring and equalization, a sample is taken again, and the specific gravity and SiC content are similarly measured. Correlation data is taken. This operation is repeated and the specific gravity to SiC content is detected each time. 2 and 3 are images showing an example of this test procedure. The white background represents the presence of Al and the black portion represents the presence of SiC. FIG. 2 shows that the tissue of the sample with a specific gravity of 2.76 is SiC: 16.30%, FIG. 3 shows an example in which the texture of a sample having a specific gravity of 2.79 was calculated by image processing as SiC: 23.10%. FIG. 1 plots data on specific gravity and SiC content in this way, and further shows this correlation as a diagram represented by an approximate line by the least squares method, and shows a linear function that absorbs experimental variations around this approximate line. In terms of regression,
SiC = {(1.73 ± α) × specific gravity− (4.60 ± β)} × 100 (Expression 1) However, α and β are constants determined by the specific gravity of the Al—Si alloy and the specific gravity of the dispersed particles, and α and β are both 0 in the central approximate line.
In the case of this embodiment, as an equation for absorbing the variation in the above-mentioned diagram, it is empirically found that SiC = {(1.73 ± 0.5) × specific gravity− (4.60 ± 1.5)} × 100. (Formula 2)
Specified by (The hatched area in Fig. 1)
[0014]
After the regression equation and approximate equation are created, actual operation is started. At least a part of the dissolved material containing the dispersed particles having an unknown content using a return material is melted and then stirred to disperse the dispersed particles contained therein, and then a sample is collected. If the specific gravity of the sample is measured, the current particle content is detected by applying it to the diagram of FIG. 1 or a regression equation (for example, the equation 2), and used as a base value for adjustment.
[0015]
To adjust the particle content, calculate from this base value, and if the particle content is insufficient, add particles, and if the particle content is excessive, dilute by adding an Al alloy material or pure Al material. There is also a method, but as mentioned above, the new addition of particles must depend on the special technology of the raw material manufacturer, and it is not always appropriate in terms of quality to incorporate it during the melting work of the casting manufacturer, The most reasonable method is to adjust the particle content by dilution by newly adding an Al alloy material or pure Al material, or by removing and concentrating only the molten Al alloy. In order to remove only the molten Al alloy, it is necessary to calm down for a certain period of time while maintaining the temperature so that the dispersed particles once dispersed uniformly by stirring are settled and separated downward due to the difference in specific gravity. The fixed time is empirically known from the properties of the master alloy, the content of dispersed particles and the material. A necessary amount is pumped out from the sedated molten Al alloy to raise the content of dispersed particles to the target value. FIG. 4 shows the microstructure of the test piece collected to confirm the sedated state, indicating that there are almost no SiC particles appearing in the black part, and the specimen is separated into a substantially complete Al alloy single body state. Yes.
[0016]
As an embodiment of the present invention, a case of dissolution A in which 100% of the return material is redissolved and dissolution B in which the ingot and the return material are combined and dissolved will be described with reference to Table 1.
The ingot (mother alloy) was an Al—Si based alloy, SiC was used as the dispersed particles, and a particle dispersed Al alloy ingot having a standard particle content of 20% and a specific gravity of 2.77 was used.
[0017]
[Table 1]
Table 1

[0018]
In Table 1, both raw materials A and B are dissolved in these raw materials, and a sample TP1 is collected after the melting. This sample TP1 is about a reference value. After the molten metal is sufficiently stirred immediately by a known stirring device (not shown) and the contained particles are uniformly dispersed in the molten metal, the sample TP2 is collected from the molten metal, and the entire molten metal is collected. Inspect specific gravity and microstructure.
At the time of this stirring, Ar gas is additionally blown and bubbled to remove impurities such as oxides and dust contained in the molten metal.
The specific gravity measurement value in the uniform dispersion state is applied to Equation 2 to detect the SiC content, and the amount of pumped or added Al alloy melt to reach the target particle content is calculated.
[0019]
Since the Al alloy melt to be pumped is more accurate as it is closer to a pure mother alloy that does not contain particles, it takes time to leave the sample until the SiC particles settle due to the difference in specific gravity after taking the sample TP2, and it is determined empirically. To do. After the SiC particles are sufficiently settled and separated, the desired amount of supernatant is pumped out from the upper Al alloy to concentrate the concentration of the particles, or the Al alloy material (ingot) containing no particles or approximately pure Al material is added. When the particle concentration is diluted and the adjustment is completed, the molten metal is stirred again to uniformly disperse the SiC particles as a whole, and a sample TP3 is collected for confirmation and casting is started. The right column of Table 1 summarizes the specific gravity of the samples TP1, TP2, and TP3 collected for each procedure and the transition of the SiC content calculated from the mathematical formulas. In both cases, the target SiC content is adjusted to a range that substantially satisfies 20%.
[0020]
【The invention's effect】
As described above, the present invention makes it easy to recycle the return material, which is inevitable in casting, with the quality completely guaranteed, in producing an Al alloy casting whose specific properties are reinforced by particle dispersion. Since the practical method of carrying out is provided, there is an effect that the difficulty in casting technology is solved and the intended particle dispersion action is reliably realized. In the future, weight reduction of members that support high-speed motion is a global trend, and it is essential that particle-dispersed Al alloy castings are applied to many types in an increasingly wide field. Expected to play a valuable role as part of material technology to back up development.
[Brief description of the drawings]
FIG. 1 is a correlation diagram of specific gravity to SiC content showing an embodiment of the present invention.
FIG. 2 is an analysis diagram (A) obtained by image processing of a microscopic structure of a sample serving as a base of the same correlation diagram, and an enlarged view (B) thereof.
FIGS. 3A and 3B are an analysis diagram (A) and an enlarged view (B) of image processing of a microscopic structure in a sample having a different particle content rate as a base of the same correlation diagram. FIGS.
FIG. 4 is an analysis diagram (A) and an enlarged view (B) of image processing of a microscopic structure of an Al alloy sample after sedation and particle separation in an embodiment of the present invention.

Claims

In the method for adjusting the particle content of an Al alloy casting in which dispersed particles are uniformly dispersed to enhance the properties, all or at least a part of the melting raw material is melted using a return material containing dispersed particles whose particle content is unknown. Then, after stirring the molten melt and uniformly dispersing the dispersed particles, the specific gravity is measured, and applied to the regression equation of the specific gravity and particle content specific to the particle-dispersed Al alloy prepared in advance, the current particle content, And the desired particle size calculated from the upper Al alloy melt after detecting the deviation from the target particle content, allowing the molten metal to stand still while keeping the temperature, and separating and settling the dispersed particles from the Al alloy melt of the base material by the specific gravity difference. Concentrate so as to match the target particle content by pumping out the amount, and again stir the molten metal to uniformly disperse the particles and then pour into the mold Particle content adjusting method of particle-dispersed Al alloy castings using light return member.

In the method for adjusting the particle content of an Al alloy casting in which dispersed particles are uniformly dispersed to enhance the properties, all or at least a part of the melting raw material is melted using a return material containing dispersed particles whose particle content is unknown. Then, after stirring the molten melt and uniformly dispersing the dispersed particles, the specific gravity is measured, and applied to the regression equation of the specific gravity and particle content specific to the particle-dispersed Al alloy prepared in advance, the current particle content, And the desired particle size calculated from the upper Al alloy melt after detecting the deviation from the target particle content, allowing the molten metal to stand still while keeping the temperature, and separating and settling the dispersed particles from the Al alloy melt of the base material by the specific gravity difference. It is characterized in that an Al alloy material is newly added in an amount to be diluted so as to match the target particle content, and the molten metal is stirred again to uniformly disperse the particles, and then poured into a mold. Grain Particle content adjusting method of particle-dispersed Al alloy castings using content unknown return member.

3. The particle content rate unknown according to claim 1 or 2, wherein the specific gravity is measured by Archimedes method, and the particle content rate is measured by preparing the regression equation based on a computerized image analysis method of the microstructure of the sample. For adjusting the particle content of a particle-dispersed Al alloy casting using any return material.

In any one of claims 1 to 3, Al alloy is Al-Si-based alloy, particles of particle-dispersed Al alloy castings using a particle content of unknown return material, characterized in that the dispersed particles are SiC Content rate adjustment method.

In claim 4, the regression equation of specific gravity and particle content is SiC = {(1.73 ± α) × specific gravity− (4.60 ± β)} × 100.
However, α and β are constants determined by the specific gravity of the Al—Si alloy and the specific gravity of the dispersed particles, and the method for adjusting the particle content of the particle-dispersed Al alloy casting using a return material whose particle content is unknown .