JP2020105545A - Aluminum alloy having low casting crack sensitivity, and aluminum alloy casting using the same - Google Patents

Aluminum alloy having low casting crack sensitivity, and aluminum alloy casting using the same Download PDF

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JP2020105545A
JP2020105545A JP2018242631A JP2018242631A JP2020105545A JP 2020105545 A JP2020105545 A JP 2020105545A JP 2018242631 A JP2018242631 A JP 2018242631A JP 2018242631 A JP2018242631 A JP 2018242631A JP 2020105545 A JP2020105545 A JP 2020105545A
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aluminum alloy
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吉田 誠
Makoto Yoshida
吉田  誠
淳矢 伊藤
Atsuya Ito
淳矢 伊藤
益大 永田
Yoshihiro Nagata
益大 永田
洋史 神戸
Yoji Kanbe
洋史 神戸
憲司 林
Kenji Hayashi
憲司 林
知男 合田
Tomoo Goda
知男 合田
大城 直人
Naoto Oshiro
直人 大城
宮尻 聡
Satoshi Miyajiri
聡 宮尻
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Waseda University
Nissan Motor Co Ltd
Daiki Aluminium Industry Co Ltd
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Waseda University
Nissan Motor Co Ltd
Daiki Aluminium Industry Co Ltd
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Abstract

To provide an aluminum alloy for casting, in which occurrence of casting cracking is reduced while the amount of Si and the amount of Sr in the alloy are reduced, and which has both high strength and high ductility (high toughness) even in an as-cast state; and an aluminum alloy casting which is formed from such an alloy and is suitable for structural members such as automobiles.SOLUTION: The aluminum alloy for casting according to the present invention includes, by wt.%: 4.00%≤Mg≤6.00%, 0.01%≤Si≤0.40%, 0.50%≤Mn≤1.50%, 0.00%≤Fe≤0.50%, 0.01%≤Ti≤0.09%, 0.0001%≤B≤0.0400%, and 0.0040%≤Sr≤0.0090%, and the balance being Al and unavoidable impurities.SELECTED DRAWING: Figure 1

Description

本発明は、鋳造割れ感受性の小さい鋳造用のアルミニウム合金と、その合金を利用したアルミニウム合金鋳物とに関する。 TECHNICAL FIELD The present invention relates to an aluminum alloy for casting, which has a low susceptibility to casting cracks, and an aluminum alloy casting using the alloy.

自動車などの輸送機器全般において軽量化が求められており、アルミニウム合金鋳物の適用が拡大している。従来より、この種の用途において、例えばトランスミッションのケースやエンジン部品などに、JIS ADC12合金が多用されているが、軽量化に対する要求は依然として高く、現在では構造部材にも適用できる高い延性(高靭性)の鋳造用アルミニウム合金が求められている。 There is a demand for weight reduction in general transportation equipment such as automobiles, and the application of aluminum alloy castings is expanding. Conventionally, in this type of application, JIS ADC12 alloy has been widely used in, for example, transmission cases and engine parts, but there is still a high demand for weight reduction, and at present, high ductility (high toughness) that can be applied to structural members as well. ) Aluminum alloy for casting is required.

そこで、JIS ADC12合金では対応が困難な構造部材の用途に対応するため、例えば、下記の特許文献1(日本国・特許第6229130号公報)には、鋳放しの状態で高延性及び高強度が得られるAl−Mg−Si系アルミニウム合金の特徴を活かしつつ、耐鋳造割れ性に優れた鋳造用アルミニウム合金として、質量%で、Sr:0.015〜0.12%,Mg:2.0〜7.5%,Si:1.65〜5.0%を含有し、鋳造後の金属組織中に晶出したMg2Siが微細な塊状になることを特徴とするものが開示されている。
この技術によれば、鋳造割れ性を改善することができると共に、内部品質に優れ、鋳放しの状態で高延性及び高強度を有するアルミニウム合金鋳物を得ることができるとされている。
Therefore, in order to deal with the use of structural members that are difficult to handle with JIS ADC12 alloy, for example, the following Patent Document 1 (Japanese Patent No. 6229130) has high ductility and high strength in the as-cast state. As an aluminum alloy for casting having excellent cast cracking resistance while utilizing the characteristics of the obtained Al-Mg-Si based aluminum alloy, Sr: 0.015 to 0.12%, Mg: 2.0 to 7.5%, Si: 1.65 to 5.0% is contained, and Mg 2 Si crystallized in the metal structure after casting is disclosed as a fine lump.
According to this technique, it is possible to improve the cast cracking property, obtain an aluminum alloy casting having excellent internal quality and high ductility and high strength in the as-cast state.

特許第6229130号公報Japanese Patent No. 6229130

しかしながら、上記のAl−Mg−Si系アルミニウム合金は、鋳造割れ性を改善できるものの、Al−Mg系合金に比べてSi量が多いため、構造部材に必要な伸びをAl−Mg系合金ほど確保できているとは言い切れず、また、Sr量が多くなると酸化物が増え、溶湯の流動性や合金の伸びの低下にもつながると言ったおそれがある。
それゆえに、本発明の主たる目的は、合金中のSi量およびSr量の低減を図りつつ鋳造割れの発生を低減させ、鋳放しの状態でも高い強度および高い延性(高靭性)を兼ね備えた鋳造用アルミニウム合金と、係る合金からなり自動車などの構造部材に好適なアルミニウム合金鋳物とを提供することにある。
However, although the Al-Mg-Si-based aluminum alloy described above can improve casting crackability, since it has a larger amount of Si than the Al-Mg-based alloy, the elongation required for the structural member is secured as much as the Al-Mg-based alloy. It cannot be said that it is made, and there is a possibility that it may be said that when the amount of Sr increases, the amount of oxides increases, which leads to deterioration of the fluidity of the molten metal and the elongation of the alloy.
Therefore, the main object of the present invention is to reduce the occurrence of casting cracks while reducing the amount of Si and Sr in the alloy, and to provide high strength and high ductility (high toughness) even in the as-cast state. An object is to provide an aluminum alloy and an aluminum alloy casting that is made of such an alloy and is suitable for a structural member such as an automobile.

本発明者らは、鋭意研究の結果、Si量およびSr量のみならず、Al−Mg系アルミニウム合金を構成する全ての化学組成を見直すことによって、鋳造割れの発生を低減させ、鋳放しの状態でも高強度と高延性とを兼ね備えた鋳造用アルミニウム合金を得ることができるのを見出し、本発明を完成するに至った。
すなわち、本発明における第1の発明は、「重量%で、4.00%≦Mg≦6.00%、0.01%≦Si≦0.40%、0.50%≦Mn≦1.50%、0.00%≦Fe≦0.50%、0.01%≦Ti≦0.09%、0.0001%≦B≦0.0400%、0.0040%≦Sr≦0.0090%を含有し、残部がAlと不可避不純物とからなる」ことを特徴とする鋳造用アルミニウム合金である。
As a result of earnest research, the present inventors have reduced the occurrence of casting cracks by reviewing not only the amount of Si and the amount of Sr but also all the chemical compositions that make up the Al-Mg-based aluminum alloy, and the as-cast state. However, they have found that an aluminum alloy for casting having both high strength and high ductility can be obtained, and completed the present invention.
That is, the first aspect of the present invention is, in terms of weight %, 4.00%≦Mg≦6.00%, 0.01%≦Si≦0.40%, 0.50%≦Mn≦1.50. %, 0.00%≦Fe≦0.50%, 0.01%≦Ti≦0.09%, 0.0001%≦B≦0.0400%, 0.0040%≦Sr≦0.0090% It is contained and the balance consists of Al and inevitable impurities."

この発明では、Siを0.01重量%以上で且つ0.40重量%以下の範囲内で、また、Srを0.0040重量%以上で且つ0.0090%重量以下の範囲内で含有させると共に、Tiを0.01重量%〜0.09重量%の範囲内で含有させ、更にはBを0.0001重量%〜0.0400重量%の範囲内で含有させているので、鋳造割れを効果的に防止することができる。加えて、所定量のFeおよびMnを含有させることにより鋳造時の焼付きを防止することができる。
以上のように、本発明では、Mgを加えた上記の7種類の元素成分を所定の割合で含有させるだけで、それらの相互的作用によって、鋳造割れの発生を低減させ、鋳放しの状態でも高い強度および高い延性を兼ね備えた鋳造用アルミニウム合金を得ることができる。
In the present invention, Si is contained in the range of 0.01% by weight or more and 0.40% by weight or less, and Sr is contained in the range of 0.0040% by weight or more and 0.0090% by weight or less. , Ti in the range of 0.01% by weight to 0.09% by weight, and B in the range of 0.0001% by weight to 0.0400% by weight. Can be prevented. In addition, it is possible to prevent seizure during casting by containing a predetermined amount of Fe and Mn.
As described above, in the present invention, the inclusion of the above-mentioned seven kinds of elemental components containing Mg at a predetermined ratio reduces the occurrence of casting cracks by their mutual action, and even in the as-cast state. An aluminum alloy for casting having high strength and high ductility can be obtained.

なお、本発明の鋳造用アルミニウム合金では、更にBeを合金全体の重量に対して0.0010〜0.0050重量%となるように添加するのが好ましい。こうすることにより、合金の酸化を防止できる。 In addition, in the aluminum alloy for casting of the present invention, it is preferable to further add Be in an amount of 0.0010 to 0.0050% by weight based on the weight of the entire alloy. By doing so, oxidation of the alloy can be prevented.

また、本発明の鋳造用アルミニウム合金では、更にCrを合金全体の重量に対して0.10〜0.40重量%となるように添加するのが好ましい。こうすることにより、結晶粒を微細化してアルミニウム合金の靱性や強度をより一層向上させることができる。 Further, in the casting aluminum alloy of the present invention, it is preferable that Cr is further added so as to be 0.10 to 0.40 wt% with respect to the weight of the entire alloy. By doing so, the crystal grains can be made finer and the toughness and strength of the aluminum alloy can be further improved.

本発明における第2の発明は、上記第1の発明に記載の鋳造用アルミニウム合金からなることを特徴とするアルミニウム合金鋳物である。
本発明の鋳造用アルミニウム合金からなるアルミニウム合金鋳物は、鋳造割れが低減されており鋳造性よく量産できると共に、鋳放しの状態でも高強度と高延性とを兼ね備えているため、例えば自動車などの構造部材として好適に使用することができる。
A second invention in the present invention is an aluminum alloy casting, comprising the aluminum alloy for casting described in the first invention.
The aluminum alloy casting comprising the aluminum alloy for casting according to the present invention has reduced casting cracks, can be mass-produced with good castability, and has both high strength and high ductility even in the as-cast state, and therefore has a structure such as an automobile. It can be suitably used as a member.

本発明によれば、合金中のSi量およびSr量の低減を図りつつ鋳造割れの発生が低減され、鋳放しの状態でも高い強度および高い延性を兼ね備えた鋳造用アルミニウム合金と、係る合金からなり自動車などの構造部材に好適なアルミニウム合金鋳物とを提供することができる。 According to the present invention, the occurrence of casting cracks is reduced while the amount of Si and Sr in the alloy is reduced, and an aluminum alloy for casting having high strength and high ductility even in an as-cast state, and An aluminum alloy casting suitable for a structural member such as an automobile can be provided.

鋳造割れ性の評価に用いたIビーム鋳型を示す模式図(平面図)である。It is a schematic diagram (plan view) which shows the I beam mold used for evaluation of casting crackability. 図1におけるA−A’線断面図である。It is the sectional view on the A-A' line in FIG.

以下、本発明の実施の形態について具体例を示しながら詳述する。
本発明の鋳造用アルミニウム合金(以下、単に「アルミニウム合金」とも言う。)は、重量%で、4.00%≦Mg≦6.00%、0.01%≦Si≦0.40%、0.50%≦Mn≦1.50%、0.00%≦Fe≦0.50%、0.01%≦Ti≦0.09%、0.0001%≦B≦0.0400%、0.0040%≦Sr≦0.0090%を含有し、残部がAlと不可避不純物とで大略構成されている。以下、各元素の特性について説明する。
Hereinafter, embodiments of the present invention will be described in detail with reference to specific examples.
The casting aluminum alloy (hereinafter, also simply referred to as “aluminum alloy”) of the present invention is 4.00%≦Mg≦6.00%, 0.01%≦Si≦0.40%, 0 by weight %. 50%≦Mn≦1.50%, 0.00%≦Fe≦0.50%, 0.01%≦Ti≦0.09%, 0.0001%≦B≦0.0400%, 0.0040 %≦Sr≦0.0090%, and the balance is made up of Al and inevitable impurities. The characteristics of each element will be described below.

Mg(マグネシウム)は、主としてアルミニウム合金中のAl母材に固溶した状態又はMgSiとして存在し、アルミニウム合金に耐力および硬さを付与する一方で、過大量の含有によって伸びが著しく低下すると共に鋳造性や耐食性にも悪影響を及ぼす成分である。
アルミニウム合金全体の重量に対するMgの含有割合は、上述したように4.00重量%以上で且つ6.00重量%以下の範囲であることが好ましい。Mgの含有割合が4.0重量%未満の場合には、鋳放しでの強度、とりわけ0.2%耐力を確保するのが困難になり、逆に、Mgの含有割合が6.00重量%を超える場合には、合金の伸びが著しく低下するようになるからである。
Mg (magnesium) exists mainly as a solid solution in an Al base material in an aluminum alloy or exists as Mg 2 Si, and imparts proof stress and hardness to the aluminum alloy, but elongation is remarkably reduced by the inclusion of an excessive amount. It is also a component that adversely affects castability and corrosion resistance.
As described above, the content ratio of Mg with respect to the weight of the entire aluminum alloy is preferably in the range of 4.00% by weight or more and 6.00% by weight or less. When the content ratio of Mg is less than 4.0% by weight, it becomes difficult to secure the strength in the as-cast condition, especially 0.2% proof stress, and conversely, the content ratio of Mg is 6.00% by weight. This is because the elongation of the alloy is remarkably reduced when the value exceeds.

Si(ケイ素)は、アルミニウム合金溶融時における流動性を確保し、鋳造性を向上させる重要な元素である。また、Al−Mg系アルミニウム合金においては、SiはMgとの金属間化合物である硬質なMg2Siを晶出して強度、とりわけ耐力の向上に寄与する。しかしながら、Mg2Siの晶出が過剰になると延性の著しい低下を招く。
アルミニウム合金全体の重量に対するSiの含有割合は、上述したように0.01重量%以上で且つ0.40重量%以下の範囲内であることが好ましく、より好ましくは0.03重量%以上で且つ0.20重量%未満の範囲内である。Siの含有割合が0.01重量%未満の場合には、溶湯の流動性を確保することが難しく、また、Mg2Siによる強度向上の効果が十分に発揮されない。逆に、Siの含有割合が0.40重量%を超える場合には、鋳造性は向上するが合金の伸び(延性)が著しく低下するようになるからである。
Si (silicon) is an important element that secures fluidity during melting of an aluminum alloy and improves castability. In the Al-Mg series aluminum alloy, Si is the strength out of hard Mg 2 Si which is an intermetallic compound of Mg crystal, especially contributes to the improvement of yield strength. However, if Mg 2 Si is excessively crystallized, ductility will be significantly lowered.
As described above, the content ratio of Si with respect to the weight of the entire aluminum alloy is preferably 0.01% by weight or more and 0.40% by weight or less, more preferably 0.03% by weight or more and It is within the range of less than 0.20% by weight. If the Si content is less than 0.01% by weight, it is difficult to secure the fluidity of the molten metal, and the strength-improving effect of Mg 2 Si is not sufficiently exerted. On the contrary, when the Si content exceeds 0.40% by weight, the castability is improved but the elongation (ductility) of the alloy is remarkably reduced.

Mn(マンガン)は、例えばダイカストなどの鋳造を行う際に、アルミニウム合金と金型との焼付きを防止する効果を有していることが知られている。しかしながら、このMnを大量に含有させると、適温での溶解が困難になると共に、Al−Mn系金属間化合物が針状に晶出してアルミニウム合金の延性が低下する。
アルミニウム合金全体の重量に対するMnの含有割合は、上述したように0.50重量%以上で且つ1.50重量%以下の範囲内であることが好ましく、より好ましくは0.70重量%以上で且つ1.20重量%以下の範囲内である。Mnの含有割合が0.50重量%未満の場合には、金型への焼付き防止効果が十分に発揮されず、逆に、Mnの含有割合が1.50重量%を超える場合には、金型への焼付き防止効果は向上するが合金の延性が著しく低下するようになるからである。
It is known that Mn (manganese) has an effect of preventing seizure between an aluminum alloy and a mold when casting such as die casting. However, when a large amount of Mn is contained, it becomes difficult to dissolve the Mn at an appropriate temperature, and the Al-Mn-based intermetallic compound crystallizes in a needle shape to reduce the ductility of the aluminum alloy.
As described above, the content ratio of Mn with respect to the weight of the entire aluminum alloy is preferably 0.50% by weight or more and 1.50% by weight or less, more preferably 0.70% by weight or more and It is within the range of 1.20% by weight or less. If the Mn content is less than 0.50% by weight, the effect of preventing seizure on the mold is not sufficiently exerted, and conversely, if the Mn content exceeds 1.50% by weight, This is because the effect of preventing seizure on the mold is improved, but the ductility of the alloy is significantly reduced.

Fe(鉄)は、上述したMnと同様に、主としてダイカストなどの鋳造時におけるアルミニウム合金と金型との焼付きを防止するためのものである。このFeもMnと同様に、大量に含有させると適温での溶解が困難になると共に、Al-Si-Feからなる針状晶を晶出し、アルミニウム合金の靱性(伸び)を低下させる。
アルミニウム合金全体の重量に対するFeの含有割合は、上述したように0.00重量%以上で且つ0.50重量%以下の範囲内であることが好ましく、より好ましくは0.07重量%以上で且つ0.30重量%以下の範囲内である。Feの含有割合が高すぎると、上記の通りAl-Si-Feからなる針状晶を晶出し、合金の伸びが低下するため、その上限は上述したように0.50重量%以下であることが好ましい。
Fe (iron) is mainly used to prevent seizure between the aluminum alloy and the mold during casting such as die casting, like Mn described above. Like Fe and Mn, when Fe is contained in a large amount, it becomes difficult to dissolve it at an appropriate temperature, and acicular crystals of Al—Si—Fe are crystallized to reduce the toughness (elongation) of the aluminum alloy.
The content ratio of Fe to the total weight of the aluminum alloy is preferably 0.00% by weight or more and 0.50% by weight or less as described above, more preferably 0.07% by weight or more and It is within the range of 0.30% by weight or less. If the Fe content is too high, needle-like crystals of Al-Si-Fe crystallize as described above and the elongation of the alloy decreases, so the upper limit is 0.50 wt% or less as described above. Is preferred.

Ti(チタン)は、結晶粒を微細化させる効果を有しており、一般的には鋳造割れの抑制や機械的性質のうち特に伸びを向上させることができる元素である。
アルミニウム合金全体の重量に対するこのTiの含有割合は、上述したように0.01重量%以上で且つ0.09重量%以下の範囲内であることが好ましく、より好ましくは0.03重量%以上で且つ0.09重量%未満の範囲内である。Tiの含有割合が0.01重量%未満の場合には、鋳造割れの抑制効果や合金の伸び向上効果が十分に発揮されず、逆に、Tiの含有割合が0.09重量%を超える場合には、鋳造割れの抑制効果や合金の伸び向上効果が頭打ちとなるのに加え、アルミニウム合金の溶解が難しくなり、溶け残りの生じる可能性が出てくるからである。
Ti (titanium) has an effect of refining crystal grains, and is generally an element capable of suppressing casting cracks and improving elongation among mechanical properties.
As described above, the content ratio of Ti with respect to the weight of the entire aluminum alloy is preferably 0.01% by weight or more and 0.09% by weight or less, and more preferably 0.03% by weight or more. It is also within the range of less than 0.09% by weight. When the content of Ti is less than 0.01% by weight, the effect of suppressing casting cracks and the effect of improving the elongation of the alloy are not sufficiently exerted. On the contrary, when the content of Ti exceeds 0.09% by weight. In addition to the effect of suppressing casting cracking and the effect of improving the elongation of the alloy, the melting of the aluminum alloy becomes difficult, and unmelted residue may occur.

B(ホウ素)は、鋳造組織の微細化に作用し、鋳造割れを抑制することができるものである。
アルミニウム合金全体の重量に対するBの含有割合は、上述したように0.0001重量%以上で且つ0.0400重量%以下の範囲内であることが好ましく、より好ましくは0.0010重量%以上で且つ0.0400重量%未満の範囲内である。Bの含有割合が0.0001重量%未満の場合には、鋳造割れの抑制効果が十分に発揮されず、逆に、Bの含有割合が0.0400重量%を超える場合には、鋳造割れの抑制効果が頭打ちになるからである。
B (boron) acts on the refinement of the cast structure and can suppress casting cracks.
As described above, the content ratio of B with respect to the weight of the entire aluminum alloy is preferably 0.0001% by weight or more and 0.0400% by weight or less, more preferably 0.0010% by weight or more and It is within the range of less than 0.0400% by weight. When the content ratio of B is less than 0.0001% by weight, the effect of suppressing casting cracks is not sufficiently exerted, and conversely, when the content ratio of B exceeds 0.0400% by weight, casting cracks are not produced. This is because the suppression effect will reach the ceiling.

Sr(ストロンチウム)は、Mg2Siの粒子を微細化させることによって、鋳造割れを抑制すると共に、アルミニウム合金の靱性や強度をより一層向上させるためのものである。
アルミニウム合金全体の重量に対するSrの含有割合は、上述したように0.0040重量%以上で且つ0.0090重量%以下の範囲内であることが好ましく、より好ましくは0.0044重量%以上で且つ0.0080重量%未満の範囲内である。Srの含有割合が0.0040重量%未満の場合には、鋳造割れの抑制効果や合金の靭性や強度の向上効果が十分に発揮されず、逆に、Srの含有割合が0.0090重量%を超える場合には、鋳造割れの抑制効果は十分に発揮されるが、酸化物が増え、溶湯の流動性の低下や合金の伸びの低下が生じるようになるからである。
Sr (strontium) is for refining the particles of Mg 2 Si to suppress casting cracks and further improve the toughness and strength of the aluminum alloy.
As described above, the content ratio of Sr with respect to the weight of the entire aluminum alloy is preferably 0.0040% by weight or more and 0.0090% by weight or less, more preferably 0.0044% by weight or more and It is within the range of less than 0.0080% by weight. When the content ratio of Sr is less than 0.0040 wt%, the effect of suppressing casting cracks and the effect of improving the toughness and strength of the alloy are not sufficiently exhibited, and conversely, the content ratio of Sr is 0.0090 wt%. If it exceeds, the effect of suppressing casting cracks is sufficiently exerted, but oxides increase, and the fluidity of the molten metal and the elongation of the alloy decrease.

以上の含有割合に従って、アルミニウム合金中のMg,Si,Mn,Fe,Ti,BおよびSrの含有割合を調整すると、鋳造割れの発生を低減させ、鋳放しの状態でも高い強度および高い延性を兼ね備えた鋳造用アルミニウム合金を得ることができる。 By adjusting the content ratios of Mg, Si, Mn, Fe, Ti, B and Sr in the aluminum alloy according to the above content ratio, the occurrence of casting cracks is reduced, and high strength and high ductility are provided even in the as-cast condition. It is possible to obtain a cast aluminum alloy.

なお、上述した各元素成分のほかに、Be(ベリリウム)を添加するようにしてもよい。このBeは、鋳造時における溶湯の酸化を防止して溶湯の流動性を更に改善すると共に、合金の靭性をより一層向上させることができる元素である。
アルミニウム合金全体の重量に対するこのBeの含有割合は、0.0010〜0.0050重量%の範囲内であることが好ましく、より好ましくは0.0020〜0.0040重量%の範囲内である。Beの含有割合が0.0010重量%未満の場合には、上述したBeの添加効果が十分に発揮されず、逆に、Beの含有割合が0.0050重量%を超える場合には、アルミニウム合金の伸びの低下が生じるようになるからである。
In addition to the above elemental components, Be (beryllium) may be added. This Be is an element that can prevent the oxidation of the molten metal during casting to further improve the fluidity of the molten metal and further improve the toughness of the alloy.
The content ratio of Be with respect to the total weight of the aluminum alloy is preferably in the range of 0.0010 to 0.0050% by weight, and more preferably in the range of 0.0020 to 0.0040% by weight. When the content ratio of Be is less than 0.0010% by weight, the above-described effect of addition of Be is not sufficiently exhibited, and conversely, when the content ratio of Be exceeds 0.0050% by weight, an aluminum alloy is used. This is because the decrease in the elongation of the

また、上述した各元素成分のほかに、更にCr(クロム)を添加するようにしてもよい。このCrは、上述したFeやMnと同様にダイカストなどの鋳造時におけるアルミニウム合金と金型との焼付きを防止するのに加え、合金の耐食性を向上させる効果を有する元素である。
アルミニウム合金全体の重量に対するCrの含有割合は、0.10〜0.40重量%の範囲内であることが好ましく、より好ましくは0.15〜0.30重量%の範囲内である。Crの含有割合が0.10重量%未満の場合には、上述の効果を十分に得ることができなくなり、逆に、Crの含有割合が0.40重量%を超える場合には、これ以上添加量を増やしても添加効果が上がらなくなるからである。
Further, in addition to each elemental component described above, Cr (chromium) may be further added. Similar to Fe and Mn described above, this Cr is an element that has the effect of preventing seizure between the aluminum alloy and the die during casting such as die casting, and improving the corrosion resistance of the alloy.
The content ratio of Cr with respect to the weight of the entire aluminum alloy is preferably in the range of 0.10 to 0.40% by weight, and more preferably in the range of 0.15 to 0.30% by weight. If the Cr content is less than 0.10% by weight, the above-mentioned effect cannot be sufficiently obtained, and conversely, if the Cr content exceeds 0.40% by weight, addition of more than this is required. This is because the effect of addition cannot be improved even if the amount is increased.

本発明のアルミニウム合金を製造する際には、まず、Al,Mg,Si,Mn,Fe,Ti,BおよびSrの各元素成分が上述した所定の割合となるように含有させた原料を準備する(必要に応じて上記のBeやCr等も添加。)。続いて、この原料を前炉付溶解炉や密閉溶解炉などの溶解炉に投入し、これらを溶解させる。溶解させた原料すなわちアルミニウム合金の溶湯は、必要に応じて脱水素処理および脱介在物処理などの精製処理が施される。そして、精製された溶湯を所定の鋳型などに流し込み、固化させることによって、アルミニウム合金の溶湯を合金地金インゴットなどに成形する。 When manufacturing the aluminum alloy of the present invention, first, a raw material containing each of the elemental components of Al, Mg, Si, Mn, Fe, Ti, B and Sr in the above-described predetermined ratio is prepared. (If necessary, the above-mentioned Be, Cr, etc. are also added.). Then, this raw material is put into a melting furnace such as a melting furnace with a front furnace or a closed melting furnace to melt them. The melted raw material, that is, the molten aluminum alloy is subjected to refining treatment such as dehydrogenation treatment and deinclusion treatment, if necessary. Then, the refined molten metal is poured into a predetermined mold or the like and solidified, so that the molten aluminum alloy is molded into an alloy metal ingot or the like.

また、本発明のアルミニウム合金を用いて、ダイカストや重力鋳造などの金型鋳造法,砂型鋳造法或いは精密鋳造法と言った様々な鋳造方法でアルミニウム合金鋳物を鋳造した後、必要に応じて溶体化処理及び時効処理などが施してもよい。本発明のアルミニウム合金は、鋳放しの状態でも高強度と高延性とを兼ね備えているが、鋳造したアルミニウム合金鋳物に対して溶体化処理および時効処理などを施すことによって当該鋳物の機械的特性を改良することもできる。 Further, using the aluminum alloy of the present invention, after casting an aluminum alloy casting by various casting methods such as a die casting method such as die casting or gravity casting, a sand casting method, or a precision casting method, a solution is formed as necessary. A chemical treatment and an aging treatment may be performed. The aluminum alloy of the present invention has both high strength and high ductility even in the as-cast state, but the mechanical properties of the cast aluminum alloy castings can be improved by subjecting them to solution treatment and aging treatment. It can be improved.

以下に、実施例を挙げて本発明を具体的に説明するが、本発明はこの実施例に限定されるものではない。
本発明に係る鋳造用アルミニウム合金の鋳造割れ性を評価すべく、下表1に示した合金組成(化学組成)の溶湯を調整し、Iビーム鋳型を用いてIビーム試験用の試験片を鋳造した。
ここで、図1および図2に、鋳造に用いたIビーム鋳型10を示す。本実施例では、拘束長さL=95mm、キャビティ部12の深さ25mmの鋳型を用いた。このIビーム鋳型10では、最終凝固部に収縮応力が集中し、割れの発生位置を一定にするため、キャビティ部12内壁の長手方向中央部に、厚さ0.5mm、長さl=20mmの断熱材14が接着されている。なお、図1および図2における符号16は、厚さ12.5mmの断熱材である。図示しないが、キャビティ部12の上面も、同じく厚さ12.5mmの断熱材であって、キャビティ部12の長手方向両端部それぞれに通じる一対の湯道が貫通された断熱材で被覆されている。
Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
In order to evaluate the casting crackability of the aluminum alloy for casting according to the present invention, a molten metal having an alloy composition (chemical composition) shown in Table 1 below was prepared, and a test piece for I-beam test was cast using an I-beam mold. did.
Here, FIGS. 1 and 2 show the I-beam mold 10 used for casting. In this embodiment, a mold having a constrained length L=95 mm and a cavity portion 12 having a depth of 25 mm was used. In this I-beam mold 10, the contraction stress concentrates on the final solidified portion, and in order to keep the crack generation position constant, a thickness of 0.5 mm and a length of l=20 mm are set at the center of the inner wall of the cavity 12 in the longitudinal direction. The heat insulating material 14 is adhered. The reference numeral 16 in FIGS. 1 and 2 is a heat insulating material having a thickness of 12.5 mm. Although not shown, the upper surface of the cavity portion 12 is also a heat insulating material having a thickness of 12.5 mm, and is covered with a heat insulating material that penetrates a pair of runners communicating with both longitudinal end portions of the cavity portion 12. ..

以上のようなIビーム鋳型10を用いてIビーム試験用の試験片を鋳造する際には、まず始めに、溶湯中の水素含有量を低減させるため、アルゴンガスによる約10分のバブリングを行った。そして、約15分間の鎮静後、溶湯をIビーム鋳型10のキャビティ部12に注湯した。注湯時の金型温度は200℃、注湯温度は720℃で鋳造を行った。 When casting a test piece for an I-beam test using the above-described I-beam mold 10, first, bubbling with an argon gas for about 10 minutes is performed to reduce the hydrogen content in the molten metal. It was Then, after sedation for about 15 minutes, the molten metal was poured into the cavity portion 12 of the I-beam mold 10. The casting was performed at a mold temperature of 200°C and a molten metal temperature of 720°C during pouring.

上記の方法で鋳造したIビーム鋳物(試験片)について、最終凝固部に生じた割れの長さを計測し、鋳造割れ性を数値的に評価するため、下式(1)により鋳造割れ性の指標(%)を算出した。
鋳造割れ性(%)=[割れの長さの合計(mm)/試験片の外周(mm)]×100 …(1)
For the I-beam casting (test piece) cast by the above method, the length of cracks generated in the final solidified portion was measured and the cast crackability was numerically evaluated. The index (%) was calculated.
Casting crackability (%)=[total length of cracks (mm)/outer circumference of test piece (mm)]×100 (1)

表1は、合金成分が本発明範囲内および範囲外にある10種類の鋳造用アルミニウム合金についてIビーム鋳造法で試験片を鋳造し、その成分組成と鋳造割れ性(%)との関係を示したものである。 Table 1 shows the relationship between the component composition and casting crackability (%) by casting a test piece by the I-beam casting method for 10 kinds of casting aluminum alloys having alloy components within and outside the range of the present invention. It is a thing.

この表1が示すように、鋳造用アルミニウム合金の合金組成が本発明範囲内にある合金1から合金3では、鋳造割れ性が50%未満であるのに対し、合金組成が本発明範囲外にある合金4〜合金10では、鋳造割れ性が50%を大きく超えるものとなった。 As shown in Table 1, in the alloys 1 to 3 in which the alloy composition of the casting aluminum alloy is within the range of the present invention, the cast cracking property is less than 50%, while the alloy composition falls outside the range of the present invention. In alloys 4 to 10, the cast cracking property greatly exceeded 50%.

本実施形態のアルミニウム合金によれば、Siを0.01重量%以上で且つ0.40重量%以下の範囲内で、また、Srを0.0040重量%以上で且つ0.0090%重量以下の範囲内で含有させると共に、Tiを0.01重量%〜0.09重量%の範囲内で含有させ、更にはBを0.0001重量%〜0.0400重量%の範囲内で含有させているので、鋳造割れを効果的に防止することができる。加えて、所定量のFeおよびMnを含有させることにより鋳造時の焼付きを防止することができる。つまり、本実施形態のアルミニウム合金では、Mgを加えた7種類の元素成分を所定の割合で含有させるだけで、それらの相互的作用によって、鋳造性に優れ、鋳放しの状態でも高い強度および高い延性を兼ね備えた鋳造用アルミニウム合金を得ることができる。 According to the aluminum alloy of the present embodiment, Si is in the range of 0.01% by weight or more and 0.40% by weight or less, and Sr is 0.0040% by weight or more and 0.0090% by weight or less. Within the range, Ti is contained within the range of 0.01% by weight to 0.09% by weight, and further B is contained within the range of 0.0001% by weight to 0.0400% by weight. Therefore, casting cracking can be effectively prevented. In addition, it is possible to prevent seizure during casting by containing a predetermined amount of Fe and Mn. That is, in the aluminum alloy of the present embodiment, only by adding the seven kinds of elemental components containing Mg in a predetermined ratio, the mutual action of them makes them excellent in castability, and has high strength and high strength even in the as-cast condition. It is possible to obtain a casting aluminum alloy having both ductility.

10:Iビーム鋳型,12:キャビティ部,14:断熱材,16:断熱材. 10: I-beam mold, 12: cavity part, 14: heat insulating material, 16: heat insulating material.

Claims (4)

重量%で、4.00%≦Mg≦6.00%、0.01%≦Si≦0.40%、0.50%≦Mn≦1.50%、0.00%≦Fe≦0.50%、0.01%≦Ti≦0.09%、0.0001%≦B≦0.0400%、0.0040%≦Sr≦0.0090%を含有し、残部がAlと不可避不純物とからなる、ことを特徴とする鋳造用アルミニウム合金。 In% by weight, 4.00%≦Mg≦6.00%, 0.01%≦Si≦0.40%, 0.50%≦Mn≦1.50%, 0.00%≦Fe≦0.50 %, 0.01% ≤ Ti ≤ 0.09%, 0.0001% ≤ B ≤ 0.0400%, 0.0040% ≤ Sr ≤ 0.0090%, with the balance being Al and inevitable impurities. An aluminum alloy for casting characterized by the following. 請求項1の鋳造用アルミニウム合金において、
更にBeを合金全体の重量に対して0.0010〜0.0050重量%となるように添加した、ことを特徴とする鋳造用アルミニウム合金。
The aluminum alloy for casting according to claim 1,
Further, Be is added in an amount of 0.0010 to 0.0050% by weight with respect to the weight of the entire alloy, and an aluminum alloy for casting is characterized.
請求項1または2の鋳造用アルミニウム合金において、
更にCrを合金全体の重量に対して0.10〜0.40重量%となるように添加した、ことを特徴とする鋳造用アルミニウム合金。
The aluminum alloy for casting according to claim 1 or 2,
Further, Cr is added so as to be 0.10 to 0.40 wt% with respect to the weight of the entire alloy, an aluminum alloy for casting.
請求項1乃至3の何れかの鋳造用アルミニウム合金からなることを特徴とするアルミニウム合金鋳物。



An aluminum alloy casting comprising the aluminum alloy for casting according to any one of claims 1 to 3.



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JP2009108409A (en) * 2007-10-12 2009-05-21 Hitachi Metals Ltd Al-Mg TYPE ALUMINUM ALLOY FOR FORGING, WITH EXCELLENT TOUGHNESS, AND CAST MEMBER COMPOSED THEREOF
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JP2004162140A (en) * 2002-11-14 2004-06-10 Toyota Motor Corp Al-Mg ALLOY FOR DIE CASTING AND METHOD FOR MANUFACTURING DIE-CAST PRODUCT MADE FROM Al-Mg ALLOY
JP2009108409A (en) * 2007-10-12 2009-05-21 Hitachi Metals Ltd Al-Mg TYPE ALUMINUM ALLOY FOR FORGING, WITH EXCELLENT TOUGHNESS, AND CAST MEMBER COMPOSED THEREOF
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