JP2010012470A - CASTING METHOD OF HYPER-EUTECTIC Al-Si BASED ALLOY, AND INGOT THEREOF - Google Patents
CASTING METHOD OF HYPER-EUTECTIC Al-Si BASED ALLOY, AND INGOT THEREOF Download PDFInfo
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本発明は、初晶Ｓｉが微細化され且つ均一に分布している過共晶Ａｌ−Ｓｉ系合金の鋳塊及びその鋳造方法に関する。 The present invention relates to an ingot of a hypereutectic Al—Si alloy in which primary crystal Si is refined and uniformly distributed, and a casting method thereof.
過共晶Ａｌ−Ｓｉ系合金は、熱膨張係数が小さく、耐熱性にも優れている。また、溶湯が凝固する際に高硬度で高剛性の初晶Ｓｉが晶出するため、耐摩耗性と剛性に優れ、ピストン、クランクケース、ブレーキドラム、シリンダーライナー、半導体製造用搬送装置、工作機械部品等の軽量化を目的として、従来の鉄鋳物を代替して使用されている。ところが、過共晶Ａｌ−Ｓｉ系合金は、初晶Ｓｉが大きく成長した鋳造組織になり易いので、この状態で塑性加工や切削加工を施すと、初晶Ｓｉとアルミニウムマトリックスの界面等に亀裂が入り、機械的性質が低下するおそれがある。また、この初晶Ｓｉが均一に分布しておらず、分布に粗密乃至偏りのある偏析状態が生じていても、機械的性質が低下するおそれがある。 A hypereutectic Al—Si alloy has a small coefficient of thermal expansion and excellent heat resistance. In addition, high-hardness and high-rigidity primary Si crystallizes when the molten metal solidifies, so it has excellent wear resistance and rigidity. Piston, crankcase, brake drum, cylinder liner, semiconductor manufacturing conveyor, machine tool It is used in place of conventional iron castings for the purpose of reducing the weight of components and the like. However, hypereutectic Al-Si alloys tend to have a cast structure in which primary crystal Si has grown greatly. If plastic processing or cutting is performed in this state, cracks will occur at the interface between primary crystal Si and the aluminum matrix. The mechanical properties may be reduced. Further, even if this primary crystal Si is not uniformly distributed and a segregation state in which the distribution is dense or uneven occurs, the mechanical properties may be deteriorated.
この初晶Ｓｉは、溶湯に初晶Ｓｉ微細化剤を添加して鋳造したり、鋳造の際に溶湯を急冷凝固することによって微細化することができるが、初晶Ｓｉの偏析状態を均一にする方法は未だ見出されていない。
例えば、特許文献１には、初晶Ｓｉ微細化剤としてＰ、Ｃａを含有させ、ＰとＣａとの質量比Ｐ／Ｃａを調整したＡｌ−Ｓｉ系合金（Ｓｉの含有量は１３〜２１質量％）の溶湯をホットトップＤＣ（Ｄｉｒｅｃｔ Ｃｈｉｌｌ）鋳造し、初晶Ｓｉを微細化する技術が開示されている。
This primary crystal Si can be refined by adding an initial crystal Si refiner to the molten metal or by rapidly solidifying the molten metal at the time of casting, but the segregation state of the primary crystal Si can be made uniform. No method has been found yet.
For example, Patent Document 1 discloses an Al—Si based alloy containing P and Ca as primary crystal Si refining agents and adjusting the mass ratio P / Ca of P and Ca (the Si content is 13 to 21 mass). %) Of the molten metal is cast by hot top DC (Direct Chill) to refine the primary crystal Si.
詳述すると、特許文献１の実施例８には、Ｓｉを１７質量％、Ｃｕを４．５質量％、Ｍｇを０．６質量％含有し、残部がＡｌである合金の溶湯を、溶湯温度７８０℃、速度１５０ｍｍ／分の鋳造条件でホットトップＤＣ鋳造法により鋳造して、直径９８ｍｍの鋳塊を製造した例が開示されている。そして、Ｐの含有量が５８ｐｐｍ、Ｃａの含有量が１ｐｐｍの場合は、鋳塊の初晶Ｓｉの粒径は４５μｍとなり、Ｐの含有量が６１ｐｐｍ、Ｃａの含有量が１７ｐｐｍ、Ｐ／Ｃａが３．２の場合は、鋳塊の初晶Ｓｉの粒径は１８μｍとなっている。
また、特許文献１の図１１には、Ｓｉの含有量が２３質量％、Ｐの含有量が６０〜８０ｐｐｍ、Ｃａの含有量が５０〜８０ｐｐｍの場合は、初晶Ｓｉは微細化されるものの粒径は３０μｍ程度であることが説明されている。
Moreover, in FIG. 11 of patent document 1, when Si content is 23 mass%, P content is 60-80 ppm, and Ca content is 50-80 ppm, although primary crystal Si is refined | miniaturized, It is explained that the particle size is about 30 μm.
しかしながら、特許文献１においては、初晶Ｓｉ微細化剤としてＰ、Ｃａを含有させたり、Ｐ／Ｃａを調整したりして、初晶Ｓｉを微細化させる技術が開示されているものの、初晶Ｓｉの分布状態には言及されていない。
そこで、本発明は、上記のような従来技術が有する問題点を解決し、初晶Ｓｉを微細化することができ且つ初晶Ｓｉを均一に分布させることのできる過共晶Ａｌ−Ｓｉ系合金の鋳造方法を提供することを課題とする。また、本発明は、初晶Ｓｉが微細化され且つ均一に分布している過共晶Ａｌ−Ｓｉ系合金の鋳塊を提供することを併せて課題とする。
However, Patent Document 1 discloses a technique for making primary Si fine by adding P and Ca as primary crystal Si refinement agents or adjusting P / Ca, but primary crystal Si is refined. No mention is made of the distribution of Si.
Therefore, the present invention solves the problems of the prior art as described above, and is a hypereutectic Al-Si alloy that can refine primary crystal Si and uniformly distribute primary crystal Si. It is an object to provide a casting method. Another object of the present invention is to provide a hypereutectic Al-Si alloy ingot in which primary crystal Si is refined and uniformly distributed.
本発明者らは、鋭意研究の結果、過共晶Ａｌ−Ｓｉ系合金の溶湯を凝固させる際に、固液共存状態の存在時間を可及的に短時間とし、固体と液体の相対的な移動を抑制すると（すなわち、Ｓｉを豊富に含有する溶湯が流動して、晶出した初晶Ｓｉに接近しにくいようにすれば）、初晶Ｓｉの偏析状態が小さくなるという知見を得て本発明を完成するに至った。
ここで固液共存状態とは、溶湯の温度が低下して液相線温度に到達した際に、初晶Ｓｉの晶出が始まるが、その初晶Ｓｉの固体と液相とが共存している状態を意味する。この固液共存状態で初晶Ｓｉは成長し、更に溶湯の温度が低下すると共晶温度に達し、共晶反応が起きると同時に初晶Ｓｉの成長も停止する。
As a result of intensive studies, the inventors of the present invention have made the existence time of the solid-liquid coexistence state as short as possible when solidifying the melt of the hypereutectic Al-Si alloy, and the relative relationship between the solid and the liquid Obtaining the knowledge that the segregation state of the primary Si becomes small if the movement is suppressed (that is, if the molten metal containing Si is made to flow and hardly approach the crystallized primary Si). The invention has been completed.
Here, the solid-liquid coexistence state means that when the temperature of the molten metal decreases and reaches the liquidus temperature, crystallization of primary Si starts, but the solid and liquid phase of primary Si coexist. Means the state. In this solid-liquid coexistence state, primary Si grows, and when the temperature of the molten metal further decreases, the eutectic temperature is reached, and at the same time as the eutectic reaction occurs, the growth of primary Si stops.
すなわち、本発明の過共晶Ａｌ−Ｓｉ系合金の鋳造方法は、初晶Ｓｉ微細化剤を含有するＡｌ−Ｓｉ系合金の溶湯を、ホットトップ部から急冷鋳型へ送って冷却凝固し、過共晶Ａｌ−Ｓｉ系合金の鋳塊を製造するホットトップＤＣ鋳造法において、前記ホットトップ部の溶湯吐出口と前記急冷鋳型の溶湯導入口とを連続させ、前記溶湯吐出口よりも前記溶湯導入口の方を大きくすることにより、前記急冷鋳型と接する前記ホットトップ部の端面を前記溶湯導入口内に露出させ、この露出した端面により形成される庇部の幅を１ｍｍ以上１０ｍｍ以下とするとともに、前記急冷鋳型で冷却される前記溶湯における液相線温度から共晶温度に至るまでの凝固時間を３秒以内とすることを特徴とする。
このような鋳造方法によれば、微細な初晶Ｓｉが均一に分布した過共晶Ａｌ−Ｓｉ系合金を得ることができる。
That is, in the method for casting a hypereutectic Al—Si alloy of the present invention, the molten Al—Si alloy containing the primary crystal refiner is sent from the hot top portion to the quenching mold and cooled and solidified. In the hot top DC casting method for producing an ingot of eutectic Al-Si alloy, the molten metal discharge port of the hot top part and the molten metal inlet of the quenching mold are made continuous, and the molten metal is introduced from the molten metal discharge port. By enlarging the mouth, the end surface of the hot top portion that is in contact with the quenching mold is exposed in the melt introduction port, and the width of the flange portion formed by the exposed end surface is 1 mm or more and 10 mm or less, The solidification time from the liquidus temperature to the eutectic temperature in the molten metal cooled by the quenching mold is within 3 seconds.
According to such a casting method, a hypereutectic Al—Si based alloy in which fine primary Si is uniformly distributed can be obtained.
なお、初晶Ｓｉ微細化剤の添加により、溶湯にＰを２０ｐｐｍ以上１３０ｐｐｍ以下含有させることが好ましく、Ｐを４０ｐｐｍ以上１３０ｐｐｍ以下含有させることがさらに好ましい。そうすれば、微細な初晶Ｓｉが均一に分布した過共晶Ａｌ−Ｓｉ系合金を、容易に得ることができる。また、初晶Ｓｉ微細化剤の添加により、溶湯にＰを２０ｐｐｍ以上１３０ｐｐｍ以下、Ｃａを６ｐｐｍ以上１３０ｐｐｍ以下含有させるとともに、ＰとＣａとの質量比Ｐ／Ｃａを０．６以上６以下に調整することがより好ましい。そうすれば、溶湯における液相線温度から共晶温度に至るまでの凝固時間を１０秒以内と遅くしても、微細な初晶Ｓｉが均一に分布した過共晶Ａｌ−Ｓｉ系合金を容易に得ることができる。
さらに、初晶Ｓｉ微細化補助剤の添加により、溶湯にＭｇ，Ｓｒ，及びＢａの少なくとも１種を含有させてもよい。初晶Ｓｉ微細化補助剤を添加した場合は、Ｍｇ，Ｓｒ，及びＢａの含有量をそれぞれ０．５質量％以下とすることが好ましい。そうすれば、より微細な初晶Ｓｉが均一に分布した過共晶Ａｌ−Ｓｉ系合金を得ることができる。
In addition, it is preferable to contain 20 ppm or more and 130 ppm or less of P in the molten metal by adding the primary Si refiner, and it is more preferable to contain P of 40 ppm or more and 130 ppm or less. By doing so, it is possible to easily obtain a hypereutectic Al—Si alloy in which fine primary crystal Si is uniformly distributed. Also, by adding the primary Si refiner, the molten metal contains P in a range of 20 ppm to 130 ppm and Ca in a range of 6 ppm to 130 ppm, and the mass ratio P / Ca of P and Ca is adjusted to 0.6 to 6 More preferably. Then, even if the solidification time from the liquidus temperature to the eutectic temperature in the molten metal is delayed to within 10 seconds, a hypereutectic Al-Si alloy in which fine primary Si is uniformly distributed can be easily obtained. Can get to.
Further, at least one of Mg, Sr, and Ba may be contained in the molten metal by adding an auxiliary agent for refining primary crystal Si. When the primary Si refinement aid is added, the contents of Mg, Sr, and Ba are each preferably 0.5% by mass or less. Then, a hypereutectic Al—Si alloy in which finer primary Si is uniformly distributed can be obtained.
また、本発明の過共晶Ａｌ−Ｓｉ系合金の鋳塊は、前述の過共晶Ａｌ−Ｓｉ系合金の鋳造方法により製造された鋳塊であって、表面から７ｍｍ内方の位置における初晶Ｓｉの偏析状態が偏析率０％であることを特徴とする。
このような構成の過共晶Ａｌ−Ｓｉ系合金の鋳塊は、優れた機械的性質や耐摩耗性を有している。特に、Ｓｉ含有量が２１質量％超過２７質量％以下である高Ｓｉ量の過共晶Ａｌ−Ｓｉ系合金の場合も、前述のような構成であれば、優れた機械的性質や耐摩耗性を備えている。
The hypereutectic Al-Si alloy ingot of the present invention is an ingot produced by the above-described hypereutectic Al-Si alloy casting method, and is the first ingot at a position 7 mm inward from the surface. The segregation state of crystal Si is characterized by a segregation rate of 0%.
An ingot of a hypereutectic Al—Si alloy having such a configuration has excellent mechanical properties and wear resistance. In particular, in the case of a hypereutectic Al—Si based alloy having a Si content exceeding 21% by mass and not more than 27% by mass, excellent mechanical properties and wear resistance can be obtained with the above-described configuration. It has.
本発明の過共晶Ａｌ−Ｓｉ系合金の鋳造方法は、初晶Ｓｉが微細化され且つ均一に分布している過共晶Ａｌ−Ｓｉ系合金の鋳塊を、容易に製造することができる。また、本発明の過共晶Ａｌ−Ｓｉ系合金の鋳塊は、優れた機械的性質や耐摩耗性を有している。 The method for casting a hypereutectic Al—Si alloy of the present invention can easily produce a hypereutectic Al—Si alloy ingot in which primary Si is refined and uniformly distributed. . Moreover, the ingot of the hypereutectic Al-Si alloy of the present invention has excellent mechanical properties and wear resistance.
アルミニウム合金の鋳造法は種々開発されているが、生産性に優れた方法として、以下のようなＤＣ鋳造法が実用に供されている。すなわち、内壁面を水冷した急冷鋳型内に樋で導いた溶湯を注ぎ、該溶湯を急冷鋳型の内壁面で冷却凝固させるとともに、凝固直後の鋳塊を下方又は側方へ順次引き出し、そこに冷却水を噴射して急冷するという鋳造法である。このような方法により、中実状又は中空状（管状）の鋳塊が得られる。 Various aluminum alloy casting methods have been developed, but the following DC casting method is put to practical use as a method with excellent productivity. That is, the molten metal guided by a slag is poured into a quenching mold whose inner wall surface is water-cooled, and the molten metal is cooled and solidified on the inner wall surface of the quenching mold, and the ingot immediately after solidification is sequentially drawn downward or sideward and cooled there It is a casting method in which water is jetted and cooled rapidly. By such a method, a solid or hollow (tubular) ingot is obtained.
該ＤＣ鋳造法においては、樋で導かれた溶湯が急冷鋳型内に直接注湯されるため、凝固終了まで溶湯が激しく流動するので、溶湯の漏れ防止のために、通常は急冷鋳型の高さ（鋳塊の引き出し方向の長さ）を高くする（例えば８０ｍｍ）。そのため、急冷鋳型に接して凝固する部分の厚さも厚く、しかも凝固収縮により生じる急冷鋳型と鋳塊との間の空隙区間も長くなり、その結果、鋳塊の一部が再溶解を起こして組織的均一性に欠ける、溶湯の流動パターンが鋳塊の凝固組織に反映して結晶粒のサイズの粗細が生じるなどの問題が発生し、製品の均一性乃至歩留まりを損ねることになる。 In the DC casting method, the molten metal guided by the slag is poured directly into the quenching mold, so that the molten metal flows vigorously until the end of solidification. Therefore, in order to prevent leakage of the molten metal, the height of the quenching mold is usually used. (Length of the ingot drawing direction) is increased (for example, 80 mm). Therefore, the thickness of the part that solidifies in contact with the quenching mold is also thick, and the gap section between the quenching mold and the ingot caused by solidification shrinkage becomes long, and as a result, part of the ingot undergoes remelting and the structure The problem is that the uniformity of the product or the yield is impaired due to the problem that the molten metal flow pattern is reflected in the solidified structure of the ingot and the crystal grain size becomes coarse.
このような溶湯の急冷鋳型内での流動を小さくする鋳造方法として、断熱湯溜部を有するホットトップ部を前記構造の急冷鋳型の上部に設けたホットトップ連続鋳造法があり、高品質の鋳塊の製造に供されている。すなわち、該ホットトップ連続鋳造法によれば、樋で導いた溶湯をホットトップ部の断熱湯溜部に一旦滞留させて溶湯の流動を抑制できるので、急冷鋳型内の溶湯の流動はかなり制限され、その結果、結晶粒のサイズの粗細差が小さくなる。しかも、溶湯温度も低くすることができるので、急冷鋳型の高さも低くでき、急冷鋳型に接して凝固する部分や急冷鋳型からの抜熱により凝固する部分が再溶解して生じる再溶解層も薄く、均一な表層の鋳塊が得られる。また、溶湯の流動パターンから生じる粗細のばらつきも小さくでき、製品の均一性乃至歩留まりを向上できる。 As a casting method for reducing the flow of the molten metal in the quenching mold, there is a hot top continuous casting method in which a hot top portion having a heat insulating hot water reservoir is provided at the upper part of the quenching mold having the above structure. It is used for mass production. That is, according to the hot top continuous casting method, the molten metal guided by the boil can be temporarily retained in the heat insulating hot water reservoir of the hot top portion to suppress the flow of the molten metal, so that the flow of the molten metal in the quenching mold is considerably limited. As a result, the coarse / fine difference in crystal grain size is reduced. In addition, since the molten metal temperature can be lowered, the height of the quenching mold can also be lowered, and the remelted layer formed by remelting the part that solidifies in contact with the quenching mold and the part that solidifies due to heat removal from the quenching mold is thin. A uniform surface ingot is obtained. In addition, it is possible to reduce the variation in coarseness and fineness caused by the flow pattern of the molten metal, and to improve the product uniformity and yield.
このようなことから、均一な表層を有する鋳塊を得るために、ホットトップ部の溶湯吐出口（すなわち、断熱湯溜部の内径）よりも急冷鋳型の溶湯導入口（すなわち、急冷鋳型の内径）の方が大きくされており、急冷鋳型と接するホットトップ部の端面を溶湯導入口内に露出させ、この露出した端面により庇部が形成されている。そして、庇部の幅（径方向長さ）は１４〜２０ｍｍ程度に設定されている。さらに、ホットトップ部と急冷鋳型との間からガスを噴出させるような工夫も行なわれている。いずれにしても、断熱湯溜部と急冷鋳型とを備えたホットトップＤＣ鋳造装置では、上記のような庇部を有する構造は必須であり、避けることができない。 For this reason, in order to obtain an ingot having a uniform surface layer, the molten metal inlet of the quenching mold (that is, the inner diameter of the quenching mold) rather than the molten metal discharge port of the hot top section (that is, the inner diameter of the heat insulating hot water reservoir). ) Is made larger, and the end surface of the hot top portion in contact with the quenching mold is exposed in the molten metal inlet, and the flange portion is formed by the exposed end surface. And the width | variety (diameter direction length) of the collar part is set to about 14-20 mm. Furthermore, a device has been devised to eject gas from between the hot top portion and the quench mold. In any case, in a hot top DC casting apparatus provided with a heat insulating hot water reservoir and a quenching mold, the structure having the flange as described above is essential and cannot be avoided.
一方、Ｓｉを１２．７質量％以上含有する過共晶Ａｌ−Ｓｉ系合金においては、加工性を付与するためには初晶Ｓｉを微細化することは必須であり、そのために初晶Ｓｉ微細化剤の添加が行われている。例えば、Ｐ及びＣａを適量含有させ、ＰとＣａとの質量比Ｐ／Ｃａを調整する必要があることは公知である。そこで、本発明者らは、過共晶Ａｌ−Ｓｉ系合金における初晶Ｓｉの晶出と成長について下記のように考察した。 On the other hand, in a hypereutectic Al-Si alloy containing 12.7% by mass or more of Si, it is essential to refine the primary crystal Si in order to impart workability. An agent is added. For example, it is known that P and Ca need to be contained in appropriate amounts and the mass ratio P / Ca of P and Ca needs to be adjusted. Therefore, the present inventors considered the crystallization and growth of primary Si in a hypereutectic Al—Si alloy as follows.
なお、過共晶Ａｌ−Ｓｉ系合金の「系」とは、Ａｌ−Ｓｉの２元系の合金だけでなく、強度、耐熱性、加工性、耐摩耗性、高剛性、その他の特性を付与するために他種の元素を含有させた３元系以上の合金を含むことを意味する。添加可能な元素としては、例えば、Ｃｕ，Ｍｇ，Ｎｉ，Ｃｒ，Ｍｎ，Ｚｎ，Ｆｅ，Ｚｒ，Ｔｉがあげられる。そして、その含有量は、例えば、Ｃｕは６質量％以下、Ｍｇは１．５質量％以下、Ｎｉは４質量％以下、Ｃｒは０．５質量％以下、Ｍｎは２．０質量％以下、Ｚｎは１．０質量％以下、Ｆｅは１．０質量％以下、Ｚｒは０．４質量％以下、Ｔｉは０．３質量％以下である。 The “system” of hypereutectic Al—Si alloy is not only Al—Si binary alloy but also strength, heat resistance, workability, wear resistance, high rigidity, and other characteristics. In order to do so, it means that a ternary or higher alloy containing other kinds of elements is included. Examples of elements that can be added include Cu, Mg, Ni, Cr, Mn, Zn, Fe, Zr, and Ti. And the content is, for example, Cu is 6 mass% or less, Mg is 1.5 mass% or less, Ni is 4 mass% or less, Cr is 0.5 mass% or less, Mn is 2.0 mass% or less, Zn is 1.0 mass% or less, Fe is 1.0 mass% or less, Zr is 0.4 mass% or less, and Ti is 0.3 mass% or less.
（１）溶湯の凝固時間を短くすると、初晶Ｓｉの成長を抑制することができる。溶解しているＳｉは状態図の液相線温度に到達してはじめて初晶Ｓｉとして晶出するから、この凝固時間とは、溶湯が液相線温度から共晶温度に至るまでの時間である。つまり、凝固時間の開始温度は、急冷鋳型に注がれる直前の溶湯の温度ではなく、液相線温度である。このように、溶解しているＳｉは、液相線温度と共晶温度との間で結晶核（初晶Ｓｉや初晶Ｓｉ微細化剤（例えばＡｌ−Ｐ化合物））に晶出し成長するものと考えられるから、溶湯の凝固時間を短くすれば、晶出した初晶Ｓｉの成長を抑制し初晶Ｓｉを微細化することができる。 (1) If the solidification time of the molten metal is shortened, the growth of primary crystal Si can be suppressed. Since the dissolved Si crystallizes as primary Si only after reaching the liquidus temperature in the phase diagram, this solidification time is the time from the molten metal to the eutectic temperature from the liquidus temperature. . That is, the start temperature of the solidification time is not the temperature of the molten metal immediately before being poured into the quenching mold, but the liquidus temperature. Thus, the dissolved Si crystallizes and grows in the crystal nucleus (primary Si or primary Si refiner (for example, Al-P compound)) between the liquidus temperature and the eutectic temperature. Therefore, if the solidification time of the molten metal is shortened, the growth of the crystallized primary crystal Si can be suppressed and the primary crystal Si can be refined.
（２）液相線温度と共晶温度との間（固液共存状態）において固体と液体の相対的な移動を抑えると、初晶Ｓｉが微細化され粗細差が小さくなり、且つ初晶Ｓｉの偏析状態が小さくなる。溶湯中に初晶Ｓｉが晶出すると、その周囲の溶湯のＳｉ含有量は少なくなる。初晶Ｓｉの結晶核の数が多ければ初晶Ｓｉは微細化される。溶湯が流動して、初晶Ｓｉの周囲の溶湯よりもＳｉ含有量の多い溶湯が先に晶出した初晶Ｓｉと接触すると、その時点で溶湯中のＳｉが晶出し初晶Ｓｉが成長し粗大化すると思われる。従来のホットトップＤＣ鋳造装置のように庇部の幅が１４〜２０ｍｍであると、庇部直下では、溶湯が渦を巻いたり流れ込むなどして流動し、溶湯の拡散が生じるため、初晶Ｓｉの成長が促され、粗細の差が大きくなるものと思われる。また、一部の初晶Ｓｉは、溶湯の流束の変化域に遍在しやすいので、初晶Ｓｉが偏析状態になりやすいものと思われる。 (2) When the relative movement of the solid and the liquid is suppressed between the liquidus temperature and the eutectic temperature (solid-liquid coexistence state), the primary Si is refined and the coarse and fine difference is reduced, and the primary Si The segregation state becomes smaller. When primary Si crystallizes in the molten metal, the Si content of the molten metal around it is reduced. If the number of crystal nuclei of primary Si is large, primary Si is miniaturized. When the molten metal flows and a molten metal having a higher Si content than the molten metal around the primary crystal Si comes into contact with the primary crystal Si crystallized first, the Si in the molten metal crystallizes and the primary crystal Si grows. It seems to be coarse. When the width of the flange is 14 to 20 mm as in the conventional hot top DC casting apparatus, the molten metal flows in a vortex or flows in just below the flange, and the diffusion of the molten metal occurs. It seems that the growth of the growth will be promoted and the difference between coarse and fine will increase. Moreover, since some primary crystal Si tends to be ubiquitous in the change region of the flux of the molten metal, it is considered that the primary crystal Si tends to be segregated.
これらの知見に基づいて本発明者らは本発明を完成するに至ったので、本発明に係る過共晶Ａｌ−Ｓｉ系合金の鋳塊及びその鋳造方法の実施の形態を、図面を参照しながら以下に詳細に説明する。図１は、過共晶Ａｌ−Ｓｉ系合金の鋳塊を製造するホットトップＤＣ鋳造装置の構造を説明する断面図である。
合金元素が常法により溶解され、必要に応じて脱滓、脱ガス処理が施されたＡｌ−Ｓｉ系合金の溶湯１が、図示しない保持炉に貯留されている。Ｓｉの含有量は、過共晶Ａｌ−Ｓｉ系合金を形成する量（約１３質量％以上）であるならば特に限定されるものではないが、２１質量％超過２７質量％以下が好ましい。また、Ａｌ−Ｓｉ系合金は、ＡｌとＳｉの２元系合金でもよいし、Ａｌ，Ｓｉの他にＣｕ，Ｍｇ，Ｎｉ，Ｃｒ，Ｍｎ，Ｚｎ，Ｆｅ，Ｚｒ，Ｔｉ等の他の合金元素を１種以上含む合金でもよい。
Based on these findings, the present inventors have completed the present invention, and therefore, referring to the drawings, embodiments of a hypereutectic Al-Si alloy ingot and a casting method thereof according to the present invention will be described. However, it explains in detail below. FIG. 1 is a cross-sectional view illustrating the structure of a hot top DC casting apparatus for producing an ingot of a hypereutectic Al—Si alloy.
An alloy element 1 is melted by a conventional method, and an Al—Si alloy melt 1 that has been degassed and degassed as necessary is stored in a holding furnace (not shown). Although content of Si will not be specifically limited if it is the quantity (about 13 mass% or more) which forms a hypereutectic Al-Si type alloy, More than 21 mass% and 27 mass% or less are preferable. The Al—Si alloy may be a binary alloy of Al and Si, or other alloy elements such as Cu, Mg, Ni, Cr, Mn, Zn, Fe, Zr, and Ti in addition to Al and Si. An alloy containing one or more of them may be used.
また、この溶湯１は、初晶Ｓｉ微細化剤を含有している。初晶Ｓｉ微細化剤の種類は特に限定されるものではないが、リン，リン含有合金，又はリン化合物が好ましく、リン，リン含有合金，又はリン化合物とカルシウム含有合金又はカルシウム化合物との両方を用いることがより好ましい。リン含有合金としては、Ａｌ−Ｐ，Ｃｕ−Ｐ，Ｆｅ−Ｐ，Ｎｉ−Ｐ等があげられ、リン化合物としてはリン酸塩，五塩化リン等があげられる。 Moreover, this molten metal 1 contains primary crystal Si refiner. Although the kind of primary crystal Si refiner is not particularly limited, phosphorus, a phosphorus-containing alloy, or a phosphorus compound is preferable, and phosphorus, a phosphorus-containing alloy, or both a phosphorus compound and a calcium-containing alloy or a calcium compound are used. More preferably, it is used. Examples of the phosphorus-containing alloy include Al-P, Cu-P, Fe-P, and Ni-P. Examples of the phosphorus compound include phosphate and phosphorus pentachloride.
初晶Ｓｉ微細化剤としてリン，リン含有合金，又はリン化合物を使用する場合には、初晶Ｓｉ微細化剤としての効果を考えると、Ｐの含有量（初晶Ｓｉ微細化剤のうちＰのみの質量により算出した含有量、以降も同様である）は２０ｐｐｍ以上１３０ｐｐｍ以下であることが好ましい。また、初晶Ｓｉ微細化剤としてリン，リン含有合金，又はリン化合物とカルシウム含有合金又はカルシウム化合物との両方を使用する場合には、初晶Ｓｉ微細化剤としての効果を考えると、Ｐの含有量は２０ｐｐｍ以上１３０ｐｐｍ以下、Ｃａの含有量は６ｐｐｍ以上１３０ｐｐｍ以下で、さらにＰとＣａとの質量比Ｐ／Ｃａは０．６以上６以下であることが好ましい。 When phosphorus, a phosphorus-containing alloy, or a phosphorus compound is used as the primary Si refiner, considering the effect as the primary Si refiner, the P content (P in the primary Si refiner) The content calculated from the mass of only the same, and so on) is preferably 20 ppm or more and 130 ppm or less. Further, when using phosphorus, a phosphorus-containing alloy, or both a phosphorus compound and a calcium-containing alloy or a calcium compound as the primary Si refiner, considering the effect as the primary Si refiner, P The content is preferably 20 ppm or more and 130 ppm or less, the Ca content is 6 ppm or more and 130 ppm or less, and the mass ratio P / Ca of P and Ca is preferably 0.6 or more and 6 or less.
さらに、初晶Ｓｉ微細化剤とともに初晶Ｓｉ微細化補助剤を用いてもよい。初晶Ｓｉ微細化補助剤としては、金属マグネシウム，マグネシウム含有合金，マグネシウム化合物，金属ストロンチウム，ストロンチウム含有合金，ストロンチウム化合物，金属バリウム，バリウム含有合金，及びバリウム化合物の少なくとも１種が好ましい。初晶Ｓｉ微細化補助剤を使用する場合には、初晶Ｓｉ微細化補助剤としての効果を考えると、Ｍｇ，Ｓｒ，Ｂａの含有量はそれぞれ０．５質量％以下であることが好ましい。 Furthermore, a primary Si refinement aid may be used together with the primary Si refiner. As the primary Si refinement aid, at least one of metal magnesium, magnesium-containing alloy, magnesium compound, metal strontium, strontium-containing alloy, strontium compound, metal barium, barium-containing alloy, and barium compound is preferable. When the primary crystal Si refinement aid is used, the content of Mg, Sr, and Ba is preferably 0.5% by mass or less in consideration of the effect as the primary crystal Si refinement aid.
なお、初晶Ｓｉ微細化剤としてリン，リン含有合金，又はリン化合物とカルシウム含有合金又はカルシウム化合物との両方を使用する場合においては、その使用効果を高めるためには、カルシウム含有合金又はカルシウム化合物の溶湯１への添加時期は鋳造直前が好ましい。添加後の保持時間が長くなると、Ｃａ−Ｐ化合物が成長して初晶Ｓｉの結晶核となるＡｌＰ化合物の形成が妨げられ、初晶Ｓｉ微細化性能が低下するためと思われる。 In addition, in the case of using phosphorus, a phosphorus-containing alloy, or both a phosphorus compound and a calcium-containing alloy or a calcium compound as the primary crystal Si refiner, in order to enhance the use effect, the calcium-containing alloy or the calcium compound The time of adding to the molten metal 1 is preferably immediately before casting. If the holding time after the addition becomes long, the Ca—P compound grows and the formation of the AlP compound that becomes the crystal nucleus of the primary Si is prevented, and the primary Si refinement performance is likely to deteriorate.
前記保持炉内の溶湯１は、樋１０を通してホットトップＤＣ鋳造装置のホットトップ部２に供給される。ホットトップ部２はセラミックス製であるとともに、円柱形の空間である断熱湯溜部３を有しており、溶湯１はこの断熱湯溜部３内に貯留される。このとき、樋１０の下流側端部における湯面Ｍ１と断熱湯溜部３内の湯面Ｍ２は、略同一高さとする。また、断熱湯溜部３内への単位時間当たりの溶湯１の流れ込み量を小さくするために、樋１０の内法を大きくしてもよい。さらに、必要に応じて、フィルタを使用して溶湯１から介在物を除去してもよい。なお、溶湯１の保温が可能で且つ高温の溶湯１により溶解，変質等が生じないならば、ホットトップ部２の材質はセラミックスに限定されるものではない。また、断熱湯溜部３の形状は円柱形に限定されるものではなく、角柱形等の他の形状でもよい。 The molten metal 1 in the holding furnace is supplied to the hot top portion 2 of the hot top DC casting apparatus through the jar 10. The hot top portion 2 is made of ceramics and has a heat insulating hot water reservoir 3 that is a cylindrical space. The molten metal 1 is stored in the heat insulating hot water reservoir 3. At this time, the hot water surface M1 in the downstream end part of the bowl 10 and the hot water surface M2 in the heat insulation hot water storage part 3 are made into the substantially same height. Further, in order to reduce the amount of molten metal 1 flowing into the heat insulating hot water reservoir 3 per unit time, the inner method of the bowl 10 may be increased. Furthermore, you may remove an inclusion from the molten metal 1 using a filter as needed. Note that the material of the hot top portion 2 is not limited to ceramics as long as the molten metal 1 can be kept warm and is not melted or altered by the high-temperature molten metal 1. Moreover, the shape of the heat insulation hot water reservoir 3 is not limited to a cylindrical shape, and may be other shapes such as a prismatic shape.
ホットトップ部２の下方には急冷鋳型４が設置されており、両者２，４は接触している。急冷鋳型４は金属製でドーナツ状をなしており、その円柱状の中心孔５内に断熱湯溜部３内の溶湯１が送られるようになっている。また、急冷鋳型４の内部は空洞となっていて、冷却水１１が循環されており、この冷却水１１で冷却された急冷鋳型４の中心孔５の内壁面によって溶湯１が冷却されるようになっている。なお、水以外の冷媒を冷却水１１の代わりに用いてもよい。 A quenching mold 4 is installed below the hot top portion 2, and both 2 and 4 are in contact with each other. The quenching mold 4 is made of metal and has a donut shape, and the molten metal 1 in the heat insulating hot water reservoir 3 is fed into the cylindrical center hole 5. Further, the inside of the quench mold 4 is hollow, and the cooling water 11 is circulated, so that the molten metal 1 is cooled by the inner wall surface of the center hole 5 of the quench mold 4 cooled by the cooling water 11. It has become. A refrigerant other than water may be used instead of the cooling water 11.
断熱湯溜部３の下端の開口部である溶湯吐出口６と、急冷鋳型４の中心孔５の上端の開口部である溶湯導入口７とは同心に配され且つ連続しており、溶湯吐出口６の直径よりも溶湯導入口７の直径の方が大径とされているため、急冷鋳型４と接するホットトップ部２の下端面の一部が溶湯導入口７内に露出しており、この露出したドーナツ状の下端面により庇部８が形成されている。そして、この庇部８の幅ｄ（径方向長さ）は、１ｍｍ以上１０ｍｍ以下とされている。 The molten metal discharge port 6 that is an opening at the lower end of the heat insulating hot water reservoir 3 and the molten metal introduction port 7 that is an opening at the upper end of the central hole 5 of the quenching mold 4 are arranged concentrically and are continuous. Since the diameter of the molten metal inlet 7 is larger than the diameter of the outlet 6, a part of the lower end surface of the hot top portion 2 in contact with the quenching mold 4 is exposed in the molten metal inlet 7. A flange 8 is formed by the exposed bottom surface of the donut. And the width | variety d (diameter direction length) of this collar part 8 shall be 1 mm or more and 10 mm or less.
急冷鋳型４の中心孔５内に導入された溶湯１は、中心孔５の内壁面で急冷され凝固し、これによりシェル１２が形成される。急冷鋳型４には、急冷鋳型４内の冷却水１１を鋳塊Ｂの表面に噴射する放水口１３が設けられているので、鋳造開始時には急冷鋳型４内に位置している図示しない受台を下方に移動させ、下方に引き出された鋳塊Ｂに冷却水１１を噴射して冷却することにより、過共晶Ａｌ−Ｓｉ系合金の鋳塊Ｂを連続して鋳造することができる。 The molten metal 1 introduced into the center hole 5 of the quench mold 4 is rapidly cooled and solidified on the inner wall surface of the center hole 5, thereby forming a shell 12. Since the quenching mold 4 is provided with a water discharge port 13 for injecting the cooling water 11 in the quenching mold 4 onto the surface of the ingot B, a cradle (not shown) located in the quenching mold 4 at the start of casting is provided. The ingot B of hypereutectic Al—Si alloy can be continuously cast by moving downward and injecting the cooling water 11 into the ingot B drawn downward to cool it.
このとき、溶湯１が冷却され液相線温度に到達すると、初晶Ｓｉが晶出し固液共存状態となり、さらに冷却されて共晶温度に到達すると凝固が完了するが、液相線温度から共晶温度に至るまでの凝固時間が所定時間以内となるように、冷却速度を制御して鋳造を行う。この所定時間は、初晶Ｓｉ微細化剤として例えばリン，リン含有合金，又はリン化合物を使用した場合は３秒であり、初晶Ｓｉ微細化剤としてリン，リン含有合金，又はリン化合物とカルシウム含有合金又はカルシウム化合物との両方を使用した場合は１０秒である。前記凝固時間が前記所定時間以内となるように冷却速度を速くするためには、鋳造速度を速くする、急冷鋳型４の高さ（鋳塊Ｂの引き出し方向の長さ）を小さくする、溶湯１の温度を高くする等の手段が考えられる。 At this time, when the molten metal 1 is cooled and reaches the liquidus temperature, primary Si is crystallized and enters a solid-liquid coexistence state, and when further cooled and reaches the eutectic temperature, solidification is completed. Casting is performed by controlling the cooling rate so that the solidification time until reaching the crystallization temperature is within a predetermined time. This predetermined time is, for example, 3 seconds when phosphorus, a phosphorus-containing alloy, or a phosphorus compound is used as the primary Si refiner, and phosphorus, a phosphorus-containing alloy, or a phosphorus compound and calcium are used as the primary Si refiner. It is 10 seconds when both the containing alloy and the calcium compound are used. In order to increase the cooling rate so that the solidification time is within the predetermined time, the casting rate is increased, the height of the quenching mold 4 (the length in the drawing direction of the ingot B) is decreased, and the molten metal 1 Means such as increasing the temperature of the gas can be considered.
なお、図１に示してある点線Ｌ1 は、温度が液相線温度である部分を示し、実線Ｌ2 は、温度が共晶温度ある部分を示す。よって、点線Ｌ1 よりも上方の部分は、初晶Ｓｉが晶出していない液相部分であり、点線Ｌ1 と実線Ｌ2 との間の部分は、初晶Ｓｉが晶出し固液共存状態となっている部分であり、実線Ｌ2 の下方の部分は、凝固が完了した部分である。 Note that a dotted line L 1 shown in FIG. 1 indicates a portion where the temperature is the liquidus temperature, and a solid line L 2 indicates a portion where the temperature is the eutectic temperature. Therefore, the part above the dotted line L 1 is a liquid phase part where the primary crystal Si is not crystallized, and the part between the dotted line L 1 and the solid line L 2 is a state where the primary crystal Si crystallizes and the solid-liquid coexistence state. The portion below the solid line L 2 is a portion where solidification has been completed.
このようにして鋳造を行えば、初晶Ｓｉが微細化され且つ均一に分布している過共晶Ａｌ−Ｓｉ系合金の鋳塊Ｂを製造することができる。すなわち、冷却速度が速く溶湯１の凝固時間が短いので、初晶Ｓｉが成長しにくく、その結果、初晶Ｓｉが微細化される。また、庇部８の幅ｄが短いので、溶湯１の流動が生じにくく、その結果、初晶Ｓｉの粗細の差が小さくなるとともに、初晶Ｓｉが偏析状態になりにくい。例えば、鋳塊Ｂの偏析状態を調べるため、表面から７ｍｍ内方の位置における初晶Ｓｉの偏析率を測定すると、０％であった。この鋳造方法によれば、上記と同様に初晶Ｓｉが微細化され且つ均一に分布している過共晶Ａｌ−Ｓｉ系合金の鋳塊を製造することができる。
このような過共晶Ａｌ−Ｓｉ系合金の鋳塊Ｂは、優れた機械的性質や耐摩耗性を有しているので、押出加工や切削加工することが容易であり、また、ピストン、クランクケース、ブレーキドラム、シリンダーライナー、半導体製造用搬送装置、工作機械部品等の部材として好適に使用することができる。
When casting is performed in this manner, a hypereutectic Al—Si alloy ingot B in which primary Si is refined and uniformly distributed can be manufactured. That is, since the cooling rate is fast and the solidification time of the molten metal 1 is short, the primary crystal Si hardly grows, and as a result, the primary crystal Si is refined. Further, since the width d of the flange portion 8 is short, the molten metal 1 is unlikely to flow, and as a result, the coarse-fine difference between the primary crystal Si is reduced and the primary crystal Si is not easily segregated. For example, in order to investigate the segregation state of the ingot B, the segregation rate of primary Si at a position 7 mm inward from the surface was measured and found to be 0%. According to this casting method, an ingot of a hypereutectic Al—Si alloy in which the primary crystal Si is refined and uniformly distributed can be produced as described above.
Such a hypereutectic Al-Si alloy ingot B has excellent mechanical properties and wear resistance, and is therefore easy to extrude and cut. It can be suitably used as a member such as a case, a brake drum, a cylinder liner, a semiconductor manufacturing transport device, or a machine tool part.
〔実施例〕
以下に、実施例を示して、本発明をさらに具体的に説明する。表１に示すような組成のＡｌ−Ｓｉ系合金の溶湯を準備した。なお、残部はＡｌ及び不可避の微量不純物である。また、表１中の数値の単位である％及びｐｐｍは、いずれも質量基準である。さらに、表１中の「−印」は微量不純物レベルの量であることを示す。
〔Example〕
Hereinafter, the present invention will be described more specifically with reference to examples. A molten Al—Si alloy having a composition as shown in Table 1 was prepared. The balance is Al and inevitable trace impurities. In addition,% and ppm, which are units of numerical values in Table 1, are based on mass. Furthermore, “-mark” in Table 1 indicates that the amount is a trace impurity level.
そして、その溶湯を用いて、前述した本実施形態とほぼ同様のホットトップＤＣ鋳造装置及び鋳造方法により鋳造を行った。その際には、庇部の幅、鋳造速度（鋳塊の下方への引き出し速度) 、及び凝固時間を種々変えて鋳造し、得られた過共晶Ａｌ−Ｓｉ系合金の鋳塊の初晶Ｓｉの平均粒径（μｍ）、初晶Ｓｉの粒径の標準偏差（σ) 、初晶Ｓｉの偏析状態を測定した。これらの測定方法を以下に示す。 And using the molten metal, it casted with the hot top DC casting apparatus and casting method substantially the same as this embodiment mentioned above. In that case, the primary crystal of the ingot of the hypereutectic Al-Si alloy obtained by casting with various changes in the width of the flange, the casting speed (speed of pulling out the ingot downward), and the solidification time. The average grain size (μm) of Si, the standard deviation (σ) of the grain size of primary Si, and the segregation state of primary Si were measured. These measuring methods are shown below.
＜凝固時間の測定方法について＞
図１に示すように、金属線に固定した熱電対２０を断熱湯溜部内に挿入し、鋳塊の鋳造と共に下降するように設定することにより、鋳塊の表面から７ｍｍ内方の位置の温度を測定した。そして、冷却曲線を作図して、凝固開始点から共晶温度に達するまでの時間を算出して、液相線温度から共晶温度に至るまでの時間とした。表面から７ｍｍ内方の位置を測定位置としたのは、庇部の下方又はその近傍に位置しており、庇部の効果を把握できる位置であるからである。
<Measurement method of coagulation time>
As shown in FIG. 1, by inserting a thermocouple 20 fixed to a metal wire into a heat insulating hot water reservoir and setting it to descend with the casting of the ingot, a temperature at a position 7 mm inward from the surface of the ingot is obtained. Was measured. Then, a cooling curve was drawn, and the time from the solidification start point to the eutectic temperature was calculated to be the time from the liquidus temperature to the eutectic temperature. The reason why the position 7 mm inward from the surface is the measurement position is that it is located below or in the vicinity of the buttocks and is a position where the effect of the buttocks can be grasped.
＜初晶Ｓｉの平均粒径及び初晶Ｓｉの粒径の標準偏差の測定方法について＞
鋳塊の表面から７ｍｍ内方の位置の鋳造組織を金属顕微鏡で観察し、観察写真をカールツァイス社製ＫＳ４００画像解析装置で解析した。画像解析の条件として、測定面積を０．９８ｍｍ2 とするとともに、円相当径５μｍ以下のものは共晶Ｓｉと判断して解析から除外した。
そして、重なり合う初晶Ｓｉを分離して測定するため、縮退処理を１回、膨張処理を１回それぞれ行い、さらに重なり合う初晶Ｓｉの重なり合う部分を手動で切り離し、個々の面積から初晶Ｓｉの円相当径を計算し、平均値と標準偏差とを求めた。
<Measurement Method of Average Deviation of Primary Si and Standard Deviation of Primary Si Particle Size>
The cast structure at a position 7 mm inward from the surface of the ingot was observed with a metal microscope, and the observation photograph was analyzed with a KS400 image analyzer manufactured by Carl Zeiss. As conditions for image analysis, the measurement area was set to 0.98 mm 2, and those with an equivalent circle diameter of 5 μm or less were determined as eutectic Si and excluded from the analysis.
In order to separate and measure the overlapping primary crystal Si, the degeneration process is performed once and the expansion process is performed once, and the overlapping parts of the overlapping primary crystal Si are manually separated, and the primary crystal Si circles are separated from the individual areas. The equivalent diameter was calculated, and the average value and standard deviation were obtained.
＜初晶Ｓｉの偏析状態の測定方法について＞
前記のようにして測定した粒径が５μｍを超える初晶Ｓｉが２個以下と判断された部分を、楕円形で近似した。そして、該楕円の短径が２００μｍ以上のものの面積の合計値を測定面積で除した値（初晶Ｓｉのない面積の占有率) を偏析率とした。
＜測定結果の判定方法について＞
偏析率が０％で、且つ、初晶Ｓｉの円相当径の平均値が３０μｍ以下のものを合格とし、各表においては○印を表示した。そして、そうでないものを不合格とし、×印を表示した。
<Measurement method of segregation state of primary Si>
The portion where the number of primary crystal Si having a particle size measured as described above exceeding 5 μm was determined to be 2 or less was approximated by an ellipse. The value obtained by dividing the total area of the ellipses whose minor axis is 200 μm or more by the measured area (occupation ratio of the area without primary Si) was defined as the segregation rate.
<About the determination method of measurement results>
A sample having a segregation rate of 0% and an average equivalent circle diameter of primary Si of 30 μm or less was accepted, and “◯” was displayed in each table. And the thing which is not so was made disqualified, and x mark was displayed.
次に、測定結果について説明する。表２に、Ｓｉの含有量が２２質量％であるＡｌ−Ｓｉ系合金の溶湯から直径５７ｍｍの鋳塊を鋳造した場合の各種鋳造条件及び測定結果を示す。 Next, the measurement result will be described. Table 2 shows various casting conditions and measurement results when an ingot having a diameter of 57 mm is cast from a molten Al-Si alloy having a Si content of 22% by mass.
試料Ｎｏ．１〜３は、庇部の幅を１０ｍｍ以下と短くし且つ凝固時間を１０秒以内と短くしたので、初晶Ｓｉの平均粒径が３０μｍ以下と微細で、偏析率が０％と均一分散していることが判る。一方、庇部の幅が長い試料Ｎｏ．４，５は、偏析率が１１％及び２１％で均一分散していないことが判る。また、凝固時間が長い試料Ｎｏ．６は、初晶Ｓｉの平均粒径が大きく初晶Ｓｉが粗大化していることが判る。
表３に、Ｓｉの含有量が２７質量％であるＡｌ−Ｓｉ系合金の溶湯から直径５７ｍｍの鋳塊を鋳造した場合の各種鋳造条件及び測定結果を示す。
Sample No. 1-3, the width of the collar portion was shortened to 10 mm or less and the solidification time was shortened to within 10 seconds, so that the average grain size of primary Si was as fine as 30 μm or less and the segregation rate was uniformly dispersed at 0%. You can see that On the other hand, Sample No. 4 and 5 show that the segregation ratios are 11% and 21% and are not uniformly dispersed. In addition, Sample No. No. 6 shows that the average grain size of primary crystal Si is large and primary crystal Si is coarsened.
Table 3 shows various casting conditions and measurement results when an ingot having a diameter of 57 mm is cast from a molten Al-Si alloy having a Si content of 27 mass%.
試料Ｎｏ．７〜９は、庇部の幅を短くし且つ凝固時間を短くしたので、初晶Ｓｉの平均粒径が３０μｍ以下と微細で、偏析率が０％と均一分散していることが判る。一方、庇部の幅が長い試料Ｎｏ．１０，１１は、偏析率が１７％及び２７％で均一分散していないことが判る。また、凝固時間が長い試料Ｎｏ．１２は、初晶Ｓｉの平均粒径が大きく初晶Ｓｉが粗大化していることが判る。
表４に、Ｓｉの含有量が２４質量％であるＡｌ−Ｓｉ系合金の溶湯から直径９７ｍｍの鋳塊を鋳造した場合の各種鋳造条件及び測定結果を示す。
Sample No. In Nos. 7 to 9, since the width of the collar portion was shortened and the solidification time was shortened, it can be seen that the average grain size of primary crystal Si is as fine as 30 μm or less and the segregation rate is uniformly dispersed at 0%. On the other hand, Sample No. 10 and 11 show that the segregation ratios are 17% and 27% and are not uniformly dispersed. In addition, Sample No. No. 12 shows that the average grain size of primary crystal Si is large and primary crystal Si is coarsened.
Table 4 shows various casting conditions and measurement results when an ingot having a diameter of 97 mm was cast from a molten Al-Si alloy having a Si content of 24 mass%.
試料Ｎｏ．１３〜１５は、庇部の幅を短くし且つ凝固時間を短くしたので、初晶Ｓｉの平均粒径が３０μｍ以下と微細で、偏析率が０％と均一分散していることが判る。また、初晶Ｓｉ微細化補助剤によるＭｇを含有する試料Ｎｏ．１６，１７は、初晶Ｓｉの平均粒径がさらに微細で、偏析率が０％で均一分散していることが判る。これらの結果から、初晶Ｓｉ微細化補助剤の効果が奏されていることが判る。 Sample No. In Nos. 13 to 15, since the width of the collar portion was shortened and the solidification time was shortened, it can be seen that the average grain size of primary Si is as fine as 30 μm or less and the segregation rate is uniformly dispersed at 0%. Sample No. 1 containing Mg by the primary crystal Si refinement aid. 16 and 17, it can be seen that the average grain size of primary Si is finer and the segregation rate is 0% and is uniformly dispersed. From these results, it can be seen that the effect of the primary Si refinement aid is exhibited.
一方、庇部の幅が長い試料Ｎｏ．１８，１９は、偏析率が１５％及び２２％で均一分散していないことが判る。また、凝固時間が長い試料Ｎｏ．２０は、初晶Ｓｉの平均粒径が大きく初晶Ｓｉが粗大化していることが判る。
表５に、Ｓｉの含有量が１７質量％であるＡｌ−Ｓｉ系合金の溶湯から直径９７ｍｍの鋳塊を鋳造した場合の各種鋳造条件及び測定結果を示す。
On the other hand, Sample No. 18 and 19 show that the segregation rates are 15% and 22%, and they are not uniformly dispersed. In addition, Sample No. No. 20 shows that the average grain size of primary Si is large and primary Si is coarsened.
Table 5 shows various casting conditions and measurement results when an ingot having a diameter of 97 mm was cast from a molten Al-Si alloy having a Si content of 17% by mass.
試料Ｎｏ．２２〜２４は、庇部の幅を短くし且つ凝固時間を短くしたので、初晶Ｓｉの平均粒径が３０μｍ以下と微細で、偏析率が０％と均一分散していることが判る。一方、庇部の幅が長い試料Ｎｏ．２６，２７は、偏析率が１９％及び３１％で均一分散していないことが判る。
試料Ｎｏ．２５は、初晶Ｓｉ微細化剤としてＰのみを含有させＣａは含有していない例であるが、庇部の幅を短くし且つ凝固時間を３秒以内と短くすれば、初晶Ｓｉの平均粒径が３０μｍ以下と微細になり、偏析率が０％と均一分散することが判る。また、試料Ｎｏ．２１（Ｓｉの含有量は２４質量％）及び試料Ｎｏ．２８も、初晶Ｓｉ微細化剤としてＰのみを含有させＣａは含有していない例であるが、凝固時間が３秒超過と長いため、初晶Ｓｉの平均粒径が３０μｍを超え粗大化していることが判る。
表６に、Ｓｉの含有量が２２質量％であるＡｌ−Ｓｉ系合金の溶湯から直径１３０ｍｍの鋳塊を鋳造した場合の各種鋳造条件及び測定結果を示す。
Sample No. In Nos. 22 to 24, since the width of the collar portion was shortened and the solidification time was shortened, it can be seen that the average grain size of primary crystal Si is as fine as 30 μm or less and the segregation rate is uniformly dispersed at 0%. On the other hand, Sample No. 26 and 27 show that the segregation rates are 19% and 31% and are not uniformly dispersed.
Sample No. 25 is an example in which only P is contained as a primary Si refiner and Ca is not contained. However, if the width of the collar portion is shortened and the solidification time is shortened to within 3 seconds, the average of primary Si It can be seen that the particle size becomes as fine as 30 μm or less and the segregation rate is uniformly dispersed at 0%. Sample No. 21 (content of Si is 24 mass%) and Sample No. 28 is an example in which only P is contained as the primary Si refinement agent and Ca is not contained, but since the solidification time is as long as 3 seconds or more, the average grain size of primary crystal Si is larger than 30 μm and coarsened. I know that.
Table 6 shows various casting conditions and measurement results when an ingot having a diameter of 130 mm is cast from a molten Al-Si alloy having a Si content of 22 mass%.
試料Ｎｏ．２９〜３１は、庇部の幅を短くし且つ凝固時間を短くしたので、初晶Ｓｉの平均粒径が３０μｍ以下と微細で、偏析率が０％と均一分散していることが判る。一方、庇部の幅が長い試料Ｎｏ．３２，３３は、偏析率が１０％及び１８％で均一分散していないことが判る。また、凝固時間が長い試料Ｎｏ．３４は、初晶Ｓｉの平均粒径が大きく初晶Ｓｉが粗大化していることが判る。 Sample No. In Nos. 29 to 31, since the width of the collar portion was shortened and the solidification time was shortened, it can be seen that the average grain size of primary crystal Si is as fine as 30 μm or less and the segregation rate is uniformly dispersed at 0%. On the other hand, Sample No. 32 and 33 show that the segregation rates are 10% and 18%, and they are not uniformly dispersed. In addition, Sample No. No. 34 shows that the average grain size of primary Si is large and primary Si is coarsened.
図２，３は、試料Ｎｏ．２９，３３の初晶Ｓｉの偏析状態を示す写真である。図２の試料Ｎｏ．２９は、初晶Ｓｉが均一に分散しており、図３の試料Ｎｏ．３３は、初晶Ｓｉが偏析していて不均一であることが判る。
なお、比較例として、庇部が無い場合の例を示す。すなわち、庇部の幅が０ｍｍであることを除いて試料Ｎｏ．２９と同様に鋳造を行った。庇部の幅を完全に０ｍｍとすることはホットトップＤＣ鋳造装置の製造上困難であり、どうしてもホットトップ部の溶湯吐出口内に急冷鋳型の端面の少なくとも一部が露出することとなるので、該部分と鋳塊との摩擦により鋳塊に肌荒れが生じ、鋳造の続行が不可能であった。また、鋳造できた部分も肌荒れがあり、偏析率が５０％であった。
2 and 3 show sample Nos. It is a photograph which shows the segregation state of 29,33 primary crystal Si. Sample No. 2 in FIG. In No. 29, primary Si is uniformly dispersed. No. 33 shows that the primary crystal Si is segregated and non-uniform.
In addition, the example in case there is no collar part is shown as a comparative example. That is, sample no. Casting was performed in the same manner as in No. 29. It is difficult to manufacture the hot top DC casting apparatus to make the width of the collar portion completely 0 mm, and at least a part of the end surface of the quenching mold is inevitably exposed in the molten metal discharge port of the hot top portion. The surface of the ingot was rough due to friction between the part and the ingot, and the casting could not be continued. Also, the casted part had rough skin, and the segregation rate was 50%.
１ 溶湯
２ ホットトップ部
３ 断熱湯溜部
４ 急冷鋳型
６ 溶湯吐出口
７ 溶湯導入口
８ 庇部
Ｂ 鋳塊
ｄ 庇部の幅
DESCRIPTION OF SYMBOLS 1 Molten metal 2 Hot top part 3 Insulation hot water storage part 4 Quenching mold 6 Molten metal discharge port 7 Molten metal introduction port 8 庇 part B Ingot d Width of heel part
Claims (5)
前記ホットトップ部の溶湯吐出口と前記急冷鋳型の溶湯導入口とを連続させ、前記溶湯吐出口よりも前記溶湯導入口の方を大きくすることにより、前記急冷鋳型と接する前記ホットトップ部の端面を前記溶湯導入口内に露出させ、この露出した端面により形成される庇部の幅を１ｍｍ以上１０ｍｍ以下とするとともに、
前記急冷鋳型で冷却される前記溶湯における液相線温度から共晶温度に至るまでの凝固時間を３秒以内とすることを特徴とする過共晶Ａｌ−Ｓｉ系合金の鋳造方法。 Hot-top DC casting method for producing a hypereutectic Al-Si-based ingot by sending a molten Al-Si-based alloy containing a primary Si refiner from a hot-top part to a quench mold and cooling and solidifying it In
The end surface of the hot top portion that is in contact with the quenching mold by causing the melt discharge port of the hot top portion and the melt introduction port of the quenching mold to be continuous and making the melt introduction port larger than the melt discharge port. And the width of the collar portion formed by the exposed end face is 1 mm or more and 10 mm or less,
A method for casting a hypereutectic Al-Si-based alloy, characterized in that a solidification time from the liquidus temperature to the eutectic temperature in the molten metal cooled by the quenching mold is within 3 seconds.
前記ホットトップ部の溶湯吐出口と前記急冷鋳型の溶湯導入口とを連続させ、前記溶湯吐出口よりも前記溶湯導入口の方を大きくすることにより、前記急冷鋳型と接する前記ホットトップ部の端面を前記溶湯導入口内に露出させ、この露出した端面により形成される庇部の幅を１ｍｍ以上１０ｍｍ以下とするとともに、
前記初晶Ｓｉ微細化剤の添加により前記溶湯にＰを２０ｐｐｍ以上１３０ｐｐｍ以下含有させ、前記急冷鋳型で冷却される前記溶湯における液相線温度から共晶温度に至るまでの凝固時間を３秒以内とすることを特徴とする過共晶Ａｌ−Ｓｉ系合金の鋳造方法。 Hot-top DC casting method for producing a hypereutectic Al-Si-based ingot by sending a molten Al-Si-based alloy containing a primary Si refiner from a hot-top part to a quench mold and cooling and solidifying it In
The end surface of the hot top portion that is in contact with the quenching mold by causing the melt discharge port of the hot top portion and the melt introduction port of the quenching mold to be continuous and making the melt introduction port larger than the melt discharge port. And the width of the collar portion formed by the exposed end face is 1 mm or more and 10 mm or less,
By adding the primary crystal Si refiner, the molten metal contains 20 ppm or more and 130 ppm or less of P, and the solidification time from the liquidus temperature to the eutectic temperature in the molten metal cooled by the quenching mold is within 3 seconds. A method for casting a hypereutectic Al-Si alloy, characterized in that:
前記ホットトップ部の溶湯吐出口と前記急冷鋳型の溶湯導入口とを連続させ、前記溶湯吐出口よりも前記溶湯導入口の方を大きくすることにより、前記急冷鋳型と接する前記ホットトップ部の端面を前記溶湯導入口内に露出させ、この露出した端面により形成される庇部の幅を１ｍｍ以上１０ｍｍ以下とするとともに、
前記初晶Ｓｉ微細化剤の添加により、ＰとＣａとの質量比Ｐ／Ｃａが０．６以上６以下となるように、前記溶湯にＰを２０ｐｐｍ以上１３０ｐｐｍ以下、Ｃａを６ｐｐｍ以上１３０ｐｐｍ以下含有させ、前記急冷鋳型で冷却される前記溶湯における液相線温度から共晶温度に至るまでの凝固時間を１０秒以内とすることを特徴とする過共晶Ａｌ−Ｓｉ系合金の鋳造方法。 Hot-top DC casting method for producing a hypereutectic Al-Si-based ingot by sending a molten Al-Si-based alloy containing a primary Si refiner from a hot-top part to a quench mold and cooling and solidifying it In
The end surface of the hot top portion that is in contact with the quenching mold by causing the melt discharge port of the hot top portion and the melt introduction port of the quenching mold to be continuous and making the melt introduction port larger than the melt discharge port. And the width of the collar portion formed by the exposed end face is 1 mm or more and 10 mm or less,
The molten metal contains P in a range of 20 ppm to 130 ppm and Ca in a range of 6 ppm to 130 ppm so that the mass ratio P / Ca of P and Ca is 0.6 to 6 by adding the primary Si refiner. And a solidification time from the liquidus temperature to the eutectic temperature in the molten metal cooled by the quenching mold is within 10 seconds.
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| CN104384462A (en) * | 2014-12-12 | 2015-03-04 | 西南铝业（集团）有限责任公司 | Hot-top casting technology of 7A05 aluminum alloy and aluminum alloy thereof |
| CN104384482A (en) * | 2014-10-29 | 2015-03-04 | 青岛科技大学 | Method for refining primary silicon in hypereutectic aluminum silicon alloy |
| CN109957686A (en) * | 2019-03-22 | 2019-07-02 | 福建工程学院 | A kind of cylinder applies alusil alloy and preparation process |
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