JP3684245B2 - Aluminum alloy for cold forging - Google Patents
Aluminum alloy for cold forging Download PDFInfo
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- JP3684245B2 JP3684245B2 JP25081594A JP25081594A JP3684245B2 JP 3684245 B2 JP3684245 B2 JP 3684245B2 JP 25081594 A JP25081594 A JP 25081594A JP 25081594 A JP25081594 A JP 25081594A JP 3684245 B2 JP3684245 B2 JP 3684245B2
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- 229910000838 Al alloy Inorganic materials 0.000 title claims description 12
- 238000010273 cold forging Methods 0.000 title claims description 5
- 229910045601 alloy Inorganic materials 0.000 claims description 30
- 239000000956 alloy Substances 0.000 claims description 30
- 229910019018 Mg 2 Si Inorganic materials 0.000 claims description 24
- 239000013078 crystal Substances 0.000 claims description 20
- 239000000463 material Substances 0.000 claims description 14
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 229910052718 tin Inorganic materials 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 238000005242 forging Methods 0.000 description 27
- 230000000694 effects Effects 0.000 description 22
- 230000032683 aging Effects 0.000 description 10
- 238000003483 aging Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 3
- 238000004881 precipitation hardening Methods 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 229910018182 Al—Cu Inorganic materials 0.000 description 2
- 229910018566 Al—Si—Mg Inorganic materials 0.000 description 2
- 229910017818 Cu—Mg Inorganic materials 0.000 description 2
- 230000003679 aging effect Effects 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 230000008014 freezing Effects 0.000 description 2
- 238000007710 freezing Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 229910018464 Al—Mg—Si Inorganic materials 0.000 description 1
- 229910010038 TiAl Inorganic materials 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 230000002431 foraging effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
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Description
【０００１】
【産業上の利用分野】
本発明は、寸法精度を必要とする薄肉鍛造加工に適したアルミニウム合金に関するものである。
【０００２】
【従来の技術】
最近、寸法精度が高く薄肉で製品強度を必要とするアルミニウム合金部材の要求が高まっている。例えば油圧部品用の各種タンクやエアーバッグのインフレーター及びパイプボディーのようなもので、成形品に厚さ４ｍｍ以下の薄肉部を有している。従来からこれらの部材は鍛造によって得ている。その際、5052合金のような非熱処理型の合金を加工硬化させて強度を持たせる方法か、あるいは6061合金のような熱処理型の合金を鍛造後、熱処理して強度をだしている。5000番系合金は鍛造時の硬度が高く、金型寿命が短い欠点がある。また、6000番系合金は高温から焼入れして熱処理する際に歪が生じ、寸法精度が悪化して製品歩留まりが低くなる欠点がある。さらに、鍛造用素材の組織の結晶粒が粗大になりやすく、鍛造時に割れたり粗大結晶粒の模様が表面に現われ、梨地外観を呈して、いわゆるオレンジピールが発生する。
【０００３】
これら従来の規格合金の欠点を解消するものとして、Ｍｇを低くしＳｎを添加したＡｌ−Ｍｇ−Ｓｉ系の遅時効硬化型鍛造用アルミニウム合金が提案されている（特開昭和６０−１３８０３９参照）。この合金はＭｇ：0.3 〜0.8 ％、Ｓｉ：0.4 〜1.5 ％、Ｃｕ：0.05〜1.0 ％、Ｓｎ：0.01〜1.0 ％、Ｔｉ：0.001 〜 0.10 ％、Ｂ：0.0001％〜0.01％及びＺｒ：0.3 ％以下、Ｍｎ：1.0 ％以下、Ｃｒ：〜0.3 ％以下のうち少なくとも１種以上を含有し、残部が不可避的不純物からなり、Ｓｉ含有量をＭｇ含有量よりも多くしたものである。
【０００４】
【発明が解決しようとする課題】
しかしながら、この合金でも常温時効性抑制効果が得られず、鍛造割れが起こる場合がある。また結晶粒が大きいので鍛造する場合に塑性流動性が悪くなり、鍛造割れが起こる。さらに強度が必ずしも充分ではないという欠点がある。
そこで鍛造性及び製品の形状凍結性は5000番系合金並みに良好であり、製品到達硬度は6000番系合金並みの冷間鍛造用アルミニウム合金の開発を目的とするものである。
【０００５】
【課題を解決するための手段】
本発明は、素材の結晶粒度を微細な範囲に規制し、微量のＳｎ添加により鍛造前に溶体化を行なっても常温時効せず、鍛造時は硬度が低くて成形性に富み、鍛造後に200 ℃以下の低温で焼き戻すことにより時効析出硬化による強度の向上が期待できるものである。また、ＭｇとＳｉの含有量を、Ｍｇ2 Ｓｉを形成するための当量関係と一定の範囲に規定することにより、常温時効効果の抑制をはかり、冷間鍛造性の改善を計ったものである。
【０００６】
即ち、本発明の合金はＭｇ：0.2〜0.75％、Ｓｉ：0.2〜1.5％、Ｃｕ：0.05〜1.0％、Ｓｎ：0.01〜1.0％、Ｔｉ：0.005〜0.20％及びＦｅ：0.1〜1.0％、Ｍｎ：0.1〜1.0％、Ｃｒ：0.05〜0.3％のうち少なくとも１種以上を含有し、残部がＡｌ及び不可避的不純物からなり、Ｍｇ2Ｓｉ≦−0.52ExＳｉ＋1.03（但し、Ｍｇ 2 Ｓｉ＝合金中のＭｇ含有量を基準とした計算上のＭｇ 2 Ｓｉ生成量 ( ％ ) ， Ex Ｓｉ＝実際に合金中に含有されているＳｉ量とＭｇ 2 Ｓｉ量に相当する計算上のＳｉ量との差である過剰のＳｉ量 ( ％ ) ）なる関係を満足し、結晶粒の平均径が１ｍｍ以下であることを基本とするアルミニウム合金である。
【０００７】
先ず、本発明のアルミニウム合金の成分限定理由を説明する。
Ｓｎ：Ｓｎは遅時効性を付与するための重要な元素である。Ｓｎ添加による常温時効の抑制効果は、Ａｌ−Ｃｕ系合金では既に知られていることである。溶体化時の凍結空孔とＳｎが結び付いて時効析出に寄与する元素の拡散を阻止して、常温時効性を抑制するとされている。0.01％以下では効果がなく、１％を越えるとその効果が飽和するだけでなく、耐食性を著しく劣化させる。
しかし、Ｍｇ添加合金ではその効果は少ない。たとえば日本金属学会誌Vol.35P.1021（1971年）によれば、6061合金に単にＳｎを添加しても、実用レベルの溶体化後１週間以上の常温時効抑制効果は認められないとされている。
【０００８】
Ｍｇ：Ｍｇは析出硬化元素であり、ＳｉとＭｇ2 Ｓｉを形成し、Ａｌ−Ｃｕ−Ｍｇを形成して強度を向上させる効果を有する。0.2 ％以下では効果がなく、0.75％を越えると溶体化後の時効硬化が起こりやすくなる。
Ｓｉ：Ｓｉも析出硬化元素であり、ＭｇとＭｇ2 Ｓｉを形成して強度を向上させる効果を有する。0.2 ％以下では効果がなく、1.5 ％を越えると溶体化後の時効硬化が起こりやすくなる。
【０００９】
ところで、Ａｌ−Ｓｉ−Ｍｇ系合金でＳｎ添加による常温時効抑制効果を発揮させるには、Ｍｇ2 Ｓｉを形成するＭｇとＳｉの含有量が大きく影響することが判かった。即ち、Ｍｇ、Ｓｉ量を変化させたＳｎ： 0.1％添加合金について 550℃水冷した場合の常温時効性について調べた。その結果を図１に示す。図１は横軸に過剰Ｓｉを、縦軸にＭｇ2 Ｓｉ量をプロットしたものである。ここで、縦軸のＭｇ2 Ｓｉ量（％）は、合金中のＭｇ含有量を基準とした計算上のＭｇ2 Ｓｉ生成量である。また、過剰Ｓｉ（ＥｘＳｉ）とは、前記Ｍｇ2 Ｓｉ量に相当する計算上のＳｉ量と、実際に合金中に含有されているＳｉ量との差である。Ｍｇ過剰の場合には負の値となる。Ｍｇ、Ｓｉ量を変化させてこれらの指標を計算し、常温時効性を測定して図１にグラフ化した。図１中で◎印は１か月でも常温時効硬化しなかったもの、○印は１〜２週間後に常温時効硬化を開始したもの、Ｘ印は溶体化の当日又は翌日より常温時効硬化を開始したものを示す。図１より常温時効硬化の抑制効果の有るものとして直線Ｍｇ2 Ｓｉ＝−0.52ExＳｉ＋1.03の下側、即ち、
Ｍｇ2 Ｓｉ≦−0.52ExＳｉ＋1.03 ・・・・（１）
なる関係が導かれた。
図１よりＭｇ2 Ｓｉの当量よりもＳｉ＜Ｍｇなる領域にも常温時効硬化抑制効果の有る領域が有ることが判かり、実用上もこの範囲の方が製品硬度が高くなる。
【００１０】
Ｃｕ：ＣｕはＡｌ−Ｃｕ−Ｍｇ、Ａｌ−Ｃｕの時効析出により合金強度を高める。含有量が 0.05 ％以下では効果がなく、１％を越えるとＭｇ、Ｓｉとの相互作用が起きて常温時効性が高まる。
【００１１】
Ｔｉ、Ｂ：微量のＴｉは鋳造組織を微細化し、素材として鍛造成形性を高める。0.005 ％未満の添加では微細化効果が得られず、 0.2％以上では初晶としてＴｉＡｌ3 が晶出し、材料欠陥となる。また、Ｔｉと共に微量のＢを添加すると一層効果的である。この場合は１ｐｐｍ未満ではその効果がなく、 500ｐｐｍを越えるとＴｉＢ2 の粗大粒子が混入して材料欠陥となる。
【００１２】
本発明のアルミニウム合金は鍛造加工時の組織が重要である。鍛造性の観点からは鍛造素材の結晶粒の大きさが非常に大きな影響を有する。結晶粒とは、押出加工後の組織あるいは溶体化後の再結晶組織の結晶粒を指す。良好な鍛造性を有するためには、結晶粒の大きさが微細であることが必須要件となる。その大きさは平均径で１ｍｍ以下、好ましくは 0.5ｍｍ以下であることを要する。結晶粒径が粗大であると塑性流動性が悪くなり、鍛造割れが起こりやすい。たとえ鍛造が可能であってもオレンジピールによる外観不良となる。適正な粒径の範囲は編曲点があるわけではないが、鍛造しようとする製品の形状や用途で決まるが、平均的な結晶粒径が１ｍｍ以下であれば問題はない。本発明合金の組織を得るには、結晶微細化剤を使用して直径１００ｍｍ以下の連続鋳造体とすれば良い。
【００１３】
Ｍｎ、Ｆｅ：ＭｎおよびＦｅはＳｉとの共存下で晶出する金属間化合物による結晶粒の微細化効果や、高温での溶体化時の２次再結晶の抑制効果が期待できる。また、製品強度を向上させる効果もある。ＭｎまたはＦｅの含有量はそれぞれ 0.1％以下ではその効果も少なく、１％を越えると巨大晶出物が生じて欠陥となる。Ｆｅは不純物として 0.2％程度混入してくるが、これらを合わせても 1.0％以下にとどめるべきである。
【００１４】
Ｃｒ：Ｃｒは結晶粒の微細化効果や、高温での溶体化時の２次再結晶の抑制効果が期待できる。 0.05 ％以下ではその効果もなく、 0.3％を越えると初晶化合物が生じ、材料欠陥となる。
【００１５】
【作用】
本発明はＭｇ含有量を低く抑え、かつＳｉとの関係をＭｇ2 Ｓｉと一定の関係を有する範囲に規定することにより、Ａｌ−Ｓｉ−Ｍｇ系合金に於てもＳｎ添加による常温時効抑制効果を発揮させるようにしたものである。
【００１６】
【実施例】
次に、ＶＴＲドラムの場合の実施例を挙げて本発明を説明する。
実施例１〜３
表１に示す組成のアルミニウム合金を溶製し、直径６７ｍｍの丸棒に連続鋳造した。この連鋳棒を表２に示す加工条件にしたがってＶＴＲ用ドラム部材に加工した。即ち、連鋳棒を直径６２．５ｍｍに面削加工し厚さ９．５ｍｍの円板状に切断した。この円板を５５０℃×６時間溶体化処理した後、ボンデ処理を施し冷間鍛造してＶＴＲドラム用に成形した。次いでこの成形材を１６０℃×８時間熱処理してＶＴＲドラム用の部材を得た。
【００１７】
【表１】
【表２】
このような加工工程を経たＶＴＲドラム部材の各特性を測定した。即ち、鋳造後の常温時効硬化を測定するため、溶体化処理直後と２週間経過後の材料の硬さを測定し、鍛造加工直前の硬さも測定した。鍛造用素材の顕微鏡組織を観察して結晶粒径を測定した。鍛造加工に際しては、割れの発生有無、オレンジピールの発生の有無、寸法精度を評価して、鍛造性の良否を判定した。最後に鍛造後熱処理して得た材料の最終硬さを測定した。これらの測定結果を表３に示す。
【００２０】
（比較例）
比較のため、本発明以外の組成の合金を実施例と同一条件で加工した場合（比較例４〜１２）、及び実施例２と同一組成の合金を直径２００ｍｍのビレットに鋳造して直径１９５ｍｍに面削加工した後、直径６２．５ｍｍに押出し加工した材料（比較例１３）について、実施例と同じ条件で特性評価した結果を表３に併記して示す。この場合、押出し後の溶体化の段階で結晶粒が粗大化した。
【００２１】
【表３】
表３から明らかなように本発明のNo.1、No.2、No.3、No.1' 、No.2' ともに溶体化処理の２週間経過後、及び鍛造直前の硬度も低く常温時効硬化が殆ど無かった。又鍛造後のＴ６、Ｔ８処理後の寸法精度も良好で鍛造加工性が優れ熱処理後に強度を発揮することが判った。比較例のNo.7、No.13では比較的良好であったが、オレンジピールが発生して外観不良となった。No.5、No.7、No.8、No.10、 No.11では鍛造直前の硬度が高く、鍛造加工で所望の寸法精度が得られなかった。 No.9 は鍛造加工では所望の寸法精度が得られたが、鍛造後の溶体化処理で所望寸法から外れた。
以上の結果から、本発明のアルミニウム合金は鋳造後の常温時効硬化が殆ど無く鍛造加工性に優れ、熱処理後に強度を発揮することが判かる。
【００２３】
【発明の効果】
本発明によれば、冷間鍛造性に優れ、加工後の強度が高い特性の優れた鍛造加工品を、従来より歩留まり良く提供することが可能となる。
【図面の簡単な説明】
【図１】ＳｉとＭｇの適正な含有量との関係を示す図である。[0001]
[Industrial application fields]
The present invention relates to an aluminum alloy suitable for thin-wall forging that requires dimensional accuracy.
[0002]
[Prior art]
Recently, there is an increasing demand for aluminum alloy members that have high dimensional accuracy and are thin and require product strength. For example, various tanks for hydraulic parts, airbag inflators, and pipe bodies, and the molded product has a thin portion with a thickness of 4 mm or less. Conventionally, these members have been obtained by forging. At that time, a non-heat treatment type alloy such as 5052 alloy is work-hardened to give strength, or a heat treatment type alloy such as 6061 alloy is forged and then heat treated to increase the strength. 5000 series alloys have the disadvantages of high hardness during forging and short mold life. In addition, the 6000 series alloy has the disadvantage that distortion occurs when it is quenched and heat-treated from a high temperature, the dimensional accuracy is deteriorated, and the product yield is lowered. Furthermore, the crystal grains of the structure of the forging material are likely to be coarse, and cracks or coarse crystal grain patterns appear on the surface during forging, exhibiting a satin appearance, and so-called orange peel is generated.
[0003]
In order to eliminate the disadvantages of these conventional standard alloys, an Al—Mg—Si based age-hardening type forging aluminum alloy in which Mg is reduced and Sn is added has been proposed (see Japanese Patent Laid-Open No. 60-138039). . This alloy is Mg: 0.3-0.8%, Si: 0.4-1.5%, Cu: 0.05-1.0%, Sn: 0.01-1.0%, Ti: 0.001-0.10%, B: 0.0001% -0.01% and Zr: 0.3% Hereinafter, at least one of Mn: 1.0% or less and Cr: 0.3% or less is contained, the balance is made of inevitable impurities, and the Si content is made larger than the Mg content.
[0004]
[Problems to be solved by the invention]
However, even with this alloy, the room temperature aging suppression effect cannot be obtained, and forging cracks may occur. Further, since the crystal grains are large, the plastic fluidity is deteriorated when forging, and forging cracks occur. Furthermore, there is a drawback that the strength is not always sufficient.
Therefore, the forging property and the product shape freezing property are as good as those of No. 5000 series alloys, and the product reaching hardness is intended to develop an aluminum alloy for cold forging that is as good as No. 6000 series alloys.
[0005]
[Means for Solving the Problems]
The present invention regulates the crystal grain size of the raw material to a fine range, and does not age at room temperature even when solutionized before forging by adding a small amount of Sn, and has low hardness and good formability during forging. Strength improvement by age precipitation hardening can be expected by tempering at a low temperature of ℃ or lower. In addition, by regulating the content of Mg and Si within a certain range and the equivalence relationship for forming Mg 2 Si, the room temperature aging effect is suppressed and cold forgeability is improved. .
[0006]
That is, the alloy of the present invention is Mg: 0.2-0.75%, Si: 0.2-1.5%, Cu: 0.05-1.0%, Sn: 0.01-1.0%, Ti: 0.005-0.20% and Fe: 0.1-1.0%, Mn : 0.1-1.0%, Cr: containing at least one of 0.05-0.3%, the balance consisting of Al and inevitable impurities , Mg 2 Si ≦ −0.52ExSi + 1.03 (However, Mg 2 Si = in the alloy) Mg 2 Si production of the calculated relative to the Mg content of (%), the difference between Ex Si = actual amount of Si on the calculation corresponding to the amount of Si and Mg 2 Si content that is contained in the alloy satisfy the excess of Si (%)) becomes the relationship is, an aluminum alloy which is based on the average diameter of the crystal grains is 1mm or less.
[0007]
First, the reasons for limiting the components of the aluminum alloy of the present invention will be described.
Sn: Sn is an important element for imparting slow aging properties. The effect of suppressing normal temperature aging due to the addition of Sn is already known in Al—Cu alloys. It is said that freezing vacancies and Sn at the time of solution formation are combined to prevent diffusion of elements contributing to aging precipitation, thereby suppressing room temperature aging. If it is less than 0.01%, there is no effect, and if it exceeds 1%, the effect is not only saturated, but also the corrosion resistance is remarkably deteriorated.
However, Mg-added alloys have little effect. For example, according to the Journal of the Japan Institute of Metals, Vol. 35P.1021 (1971), it is said that even if Sn is simply added to 6061 alloy, the effect of suppressing aging at room temperature for more than one week after solution at a practical level is not recognized. Yes.
[0008]
Mg: Mg is a precipitation hardening element, and has the effect of forming Si and Mg 2 Si and forming Al—Cu—Mg to improve the strength. If it is 0.2% or less, there is no effect, and if it exceeds 0.75%, age hardening after solution treatment tends to occur.
Si: Si is also a precipitation hardening element, and has the effect of improving strength by forming Mg and Mg 2 Si. If it is less than 0.2%, there is no effect, and if it exceeds 1.5%, age hardening after solution treatment tends to occur.
[0009]
By the way, it was found that the contents of Mg and Si forming Mg 2 Si greatly influence the Al—Si—Mg-based alloy to exhibit the normal temperature aging suppression effect by adding Sn. In other words, Sn: 0.1% added alloy with varying amounts of Mg and Si was examined for aging at room temperature when water-cooled at 550 ° C. The result is shown in FIG. FIG. 1 is a plot of excess Si on the horizontal axis and the amount of Mg 2 Si on the vertical axis. Here, the amount of Mg 2 Si (%) on the vertical axis is the calculated amount of Mg 2 Si generated based on the Mg content in the alloy. Excess Si (ExSi) is the difference between the calculated Si amount corresponding to the Mg 2 Si amount and the Si amount actually contained in the alloy. When Mg is excessive, a negative value is obtained. These indexes were calculated by changing the amounts of Mg and Si, and the normal temperature aging was measured and graphed in FIG. In Fig. 1, ◎ indicates that the material did not age at room temperature even after one month, ○ indicates that the material has been aged at room temperature after 1 to 2 weeks, and X indicates that the material has been aged at room temperature or on the day after the solution treatment. Shows what As shown in FIG. 1, the lower side of the straight Mg 2 Si = −0.52ExSi + 1.
Mg 2 Si ≦ −0.52ExSi + 1.03 (1)
The relationship was led.
From FIG. 1, it can be seen that there is a region having an effect of suppressing the normal temperature age hardening even in a region where Si <Mg is more than the equivalent of Mg 2 Si, and in this range, the product hardness is higher in this range.
[0010]
Cu: Cu increases the alloy strength by aging precipitation of Al-Cu-Mg and Al-Cu. If the content is less than 0.05%, there is no effect, and if it exceeds 1%, interaction with Mg and Si occurs and the normal temperature aging increases.
[0011]
Ti, B: A small amount of Ti refines the cast structure and enhances forgeability as a raw material. If the addition is less than 0.005%, the effect of miniaturization cannot be obtained. If the addition is 0.2% or more, TiAl 3 crystallizes as the primary crystal, resulting in a material defect. It is more effective to add a small amount of B together with Ti. In this case, if it is less than 1 ppm, there is no effect, and if it exceeds 500 ppm, TiB 2 coarse particles are mixed, resulting in a material defect.
[0012]
In the aluminum alloy of the present invention, the structure during forging is important. From the viewpoint of forgeability, the size of the crystal grains of the forging material has a great influence. A crystal grain refers to the crystal grain of the structure after extrusion, or the recrystallized structure after solution forming. In order to have good forgeability, it is an essential requirement that the size of crystal grains is fine. The size is required to be an average diameter of 1 mm or less, preferably 0.5 mm or less. When the crystal grain size is coarse, the plastic fluidity is deteriorated and forging cracks are likely to occur. Even if forging is possible, the appearance will be poor due to orange peel. The appropriate range of the grain size does not have an inflection point, but is determined by the shape and application of the product to be forged, but there is no problem if the average crystal grain size is 1 mm or less. In order to obtain the structure of the alloy of the present invention, a continuous cast body having a diameter of 100 mm or less may be formed using a crystal refining agent.
[0013]
Mn, Fe: Mn and Fe can be expected to have an effect of refining crystal grains due to an intermetallic compound that crystallizes in the presence of Si, and an effect of suppressing secondary recrystallization during solution treatment at high temperatures. It also has the effect of improving product strength. When the content of Mn or Fe is 0.1% or less, the effect is small, and when the content exceeds 1%, giant crystallized substances are formed and defects are caused. Fe is mixed in at about 0.2% as an impurity, but when combined, it should be kept below 1.0%.
[0014]
Cr: Cr can be expected to have an effect of refining crystal grains and an effect of suppressing secondary recrystallization during solution treatment at high temperatures. If it is less than 0.05%, there is no effect, and if it exceeds 0.3%, a primary crystal compound is formed, resulting in a material defect.
[0015]
[Action]
In the present invention, the Mg content is kept low, and the relationship with Si is regulated in a range having a certain relationship with Mg 2 Si, so that the effect of suppressing the aging at room temperature by the addition of Sn in an Al—Si—Mg alloy is also achieved. Is intended to demonstrate.
[0016]
【Example】
Next, the present invention will be described with reference to an example in the case of a VTR drum.
Examples 1-3
An aluminum alloy having the composition shown in Table 1 was melted and continuously cast into a round bar having a diameter of 67 mm. This continuous cast bar was processed into a drum member for VTR according to the processing conditions shown in Table 2. That is, the continuous cast bar was chamfered to a diameter of 62.5 mm and cut into a disk shape having a thickness of 9.5 mm. This disk was subjected to a solution treatment at 550 ° C. for 6 hours, then subjected to a bondage treatment and cold forging to form a VTR drum. Next, this molded material was heat-treated at 160 ° C. for 8 hours to obtain a member for a VTR drum.
[0017]
[Table 1]
[Table 2]
Each characteristic of the VTR drum member which passed through such a processing process was measured. That is, in order to measure the normal temperature age hardening after casting, the hardness of the material was measured immediately after the solution treatment and after 2 weeks, and the hardness just before forging was also measured. The crystal grain size was measured by observing the microstructure of the forging material. In the forging process, whether or not cracking occurred, whether or not orange peel occurred, and dimensional accuracy were evaluated to determine whether the forgeability was good. Finally, the final hardness of the material obtained by heat treatment after forging was measured. These measurement results are shown in Table 3.
[0020]
(Comparative example)
For comparison, when an alloy having a composition other than that of the present invention was processed under the same conditions as in the examples (Comparative Examples 4 to 12), an alloy having the same composition as in Example 2 was cast into a billet having a diameter of 200 mm to a diameter of 195 mm. Table 3 shows the results of the characteristic evaluation of the material (Comparative Example 13) extruded to a diameter of 62.5 mm after chamfering under the same conditions as in the Examples. In this case, the crystal grains became coarse in the solution treatment stage after extrusion.
[0021]
[Table 3]
As is clear from Table 3, the hardness of the No. 1, No. 2, No. 3, No. 1 'and No. 2' of the present invention is low at room temperature after 2 weeks of solution treatment and immediately before forging. There was almost no hardening. It was also found that the dimensional accuracy after T6 and T8 treatment after forging was good, the forging workability was excellent, and the strength was exhibited after heat treatment. The comparative examples No. 7 and No. 13 were relatively good, but an orange peel occurred and the appearance was poor. In No. 5, No. 7, No. 8, No. 10, No. 11, the hardness immediately before forging was high, and the desired dimensional accuracy could not be obtained by forging. For No. 9, the desired dimensional accuracy was obtained in the forging process, but it was out of the desired dimension in the solution treatment after forging.
From the above results, it can be seen that the aluminum alloy of the present invention has almost no room temperature age hardening after casting, is excellent in forgeability and exhibits strength after heat treatment.
[0023]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the forge processed goods excellent in the cold forgeability and the characteristic with the high intensity | strength after a process with a yield higher than before.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the proper content of Si and Mg.
Claims (3)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25081594A JP3684245B2 (en) | 1993-11-24 | 1994-10-17 | Aluminum alloy for cold forging |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5-293629 | 1993-11-24 | ||
| JP29362993 | 1993-11-24 | ||
| JP25081594A JP3684245B2 (en) | 1993-11-24 | 1994-10-17 | Aluminum alloy for cold forging |
Publications (2)
| Publication Number | Publication Date |
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| JPH07197163A JPH07197163A (en) | 1995-08-01 |
| JP3684245B2 true JP3684245B2 (en) | 2005-08-17 |
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| JP5088703B2 (en) * | 1999-06-16 | 2012-12-05 | 日本軽金属株式会社 | Al-Mg-Si aluminum alloy cold forging with excellent appearance quality |
| DE19953212A1 (en) * | 1999-11-05 | 2001-05-31 | Fuchs Fa Otto | Wrought aluminum alloy |
| CN103103411A (en) * | 2012-11-05 | 2013-05-15 | 熊科学 | Magnesium-containing aluminium alloy for hot processed tubes |
| ES2702729T3 (en) * | 2016-01-22 | 2019-03-05 | Amag Rolling Gmbh | Hardenable aluminum alloy based on Al-Mg-Si |
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