JP2004292932A - Iron-carbon alloy for precast forming, precast forming method using it, and precast formed article - Google Patents
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【０００１】
【発明の属する技術分野】
本発明は半溶融成形用鉄−炭素系合金とそれを用いた半溶融成形法及び半溶融成形体に関する。
【０００２】
【従来の技術】
亜共晶成分の鋳鉄を用いて、これを半溶融状態に加熱して成形を行う半溶融成形法が適用されつつある。この場合、素材に用いる亜共晶鋳鉄は白銑であることが望ましい。その理由は、同じ成分の鋳鉄であっても、白銑化した鋳鉄の方がデンドライトが微細となるため、半溶融状態における固相の径も小さく、よって得られた成形体の機械的性質が優れること、及び黒鉛化した鋳鉄を用いる場合には、半溶融温度に加熱した際に黒鉛周辺から溶融するため、固相と液相とが不均一となり、その結果、同じ温度に加熱した場合でも白銑化鋳鉄に比べて液相の流出が生じ易く、よって半溶融成形に供する半溶融ビレット等における形状保持がより難しくなることによるものである。
一方、前記亜共晶鋳鉄を白銑化して用いた場合でも、半溶融温度にした状態においてデンドライト組織が残っていると、粘性が高く、金型空間への充填不良、固相と液相との分離が生じやすいという問題があった。
この問題を解決する１つの手段として、例えば特許第３０９６１７６号及び特開平８−９０１９１号に係る発明が開示されている。これらの開示された発明では、白鋳鉄或いは球状黒鉛鋳鉄のダイカストに関して、金型空間へのゲート面積をプランジャー加圧面積の１／１０以下とすることで、デンドライト組織をゲート通過の際に良好に破壊するようにした技術手法が提供されている。
また更に他の鋳鉄の半溶融成形法としては、半溶融成形による凝固時における成形体の組織は白銑組織とし、その後に成形体を熱処理することで、白銑を黒鉛化させる手法がある。この手法では、前記熱処理により黒鉛は塊状に近くなるため、球状黒鉛鋳鉄に匹敵する機械的性質が得られる可能性がある。
【０００３】
【発明が解決しようとする課題】
ところが上記特許第３０９６１７６号及び特開平８−９０１９１号に係る発明に示す技術手法では、ゲートを絞り過ぎるため、厚肉部を有する成形体を、空気の巻き込みや鋳巣等の内部欠陥なく成形することが難しいという問題があった。その原因は、上記技術手法では径を非常に小さくしたゲート部が金型内の厚肉部よりも早く凝固してしまい、よってゲート部を通じ厚肉部の未凝固溶湯に対して外部からの加圧を加えることが困難となって鋳巣が生じ易くなるためである。またゲート径が非常に絞られていることから、金型への注入の際に乱流が発生し易く、空気の巻き込みが発生し易いからである。
また一方、上記した半溶融成形による凝固時の成形体の組織を白銑となるようにし、その後の熱処理によって白銑を黒鉛化させる手法の場合は、半溶融成形された成形体の厚肉部では、凝固時の冷却速度が遅いため、片状または共晶状黒鉛が晶出する場合が多くなり、その結果、その後に熱処理においても、これら晶出黒鉛の形状を塊状に変えることは困難で、機械的性質がむしろ低下するおそれがあるという問題があった。
【０００４】
そこで本発明は上記従来の鋳鉄を用いた半溶融成形の問題点を解消し、半溶融成形において機械的性質やその他の性質が良好な成形体を得ることができる半溶融成形用鉄−炭素合金の提供を課題とする。またその半溶融成形用鉄−炭素系合金を用いて良好な機械的性質やその他の性質を得ることができる半溶融成形法及び半溶融成形体の提供を課題とする。
【０００５】
【課題を解決するための手段】
上記課題を解決するため、本発明の半溶融成形用鉄−炭素系合金は、半溶融成形用に供される鉄−炭素系合金であって、成分組成が重量％で、Ｃ：２．００〜３．００％、Ｓｉ：１．５０〜３．００％、炭素当量（Ｃ＋１／３Ｓｉ）：２．５０〜３．５０％、Ｍｇ：０．０１５〜０．０３５％を含有すると共に、残部が実質的にＦｅからなり、且つ組織を白銑化させてあることを第１の特徴としている。
また本発明の半溶融成形用鉄−炭素系合金は、上記第１の特徴に加えて、ＣａとＣｅの何れか１種若しくは両方を、重量％で、Ｃａ：０．００５〜０．０５０％、Ｃｅ：０．００５〜０．０２０％含有させることを第２の特徴としている。また本発明の半溶融成形法は、上記第１又は第２の特徴に記載の半溶融成形用鉄−炭素系合金を固相と液相とが共存した半溶融状態にして金型等の型空間に充填すると共に、該充填された材料の型空間内での部位のうち凝固終了に要する時間が２秒以上かかる部位に対して７．０ＭＰａ以上の圧力が充填完了時において加わるように、前記充填された材料に圧力を加えることを第３特徴としている。また本発明の半溶融成形体は、上記第１又は第２の特徴に記載の半溶融成形用鉄−炭素系合金を上記第３の特徴に記載の半溶融成形法を施して成形した後、８５０〜１０００℃の温度、３０〜６０分の保持時間で黒鉛化熱処理を施すことにより、黒鉛粒径が６０μｍ以下で、球状化率が７０％以上の球状黒鉛を有する内部組織としたことを第４の特徴としている。
【０００６】
上記第１の特徴による半溶融用鉄−炭素系合金によれば、そこに示されるＣとＳｉの成分組成により、材料を半溶融させるのに必要な温度（材料の半溶融温度）があまり高くならないように抑制することができる。これにより半溶融成形に用いられる金型等の型の熱負担が減り、寿命を長くすることができる。
また上記ＣとＳｉの組成に加えてＭｇを示された含有量で添加することで、溶湯の酸化に伴う酸化物の巻き込み等を防止しつつ、半溶融成形に供する素材としての鉄−炭素系合金を必要十分に白銑化することができ、またデンドライトの粗大化を抑制して十分に微細に調整することができる。これによって、半溶融状態での材料の金型空間へ注入の際における充填不良や固相と液相との分離を無くすことができる。またＭｇの添加により溶湯の粘度を高めて注入の際の空気の巻き込みを低減することができる。
また上記Ｃ、Ｓｉ、Ｍｇの成分組成により、半溶融成形の際における凝固組織を白銑化し、また機械的性質の劣化原因となる共晶状や片状の黒鉛の晶出を防止することができる。
またＣ、Ｓｉ、Ｍｇの成分組成により、半溶融成形によって得られた成形体を黒鉛化熱処理する場合において、白銑の塊状黒鉛化、更にはその球状化と微細化を促進させることができる。
よって第１の特徴による半溶融成形用鉄−炭素系合金によれば、半溶融成形における型の熱負担を軽減してその寿命を長くすることができると共に、半溶融加工の際に得られる成形体に鋳巣やその他の欠陥が少なく且つ粗大なデンドライト組織や共晶状或いは片状の黒鉛が生じない白銑の凝固組織を可能にすることができる。更に半溶融成形後の熱処理により、成形体の組織を微細な塊状或いは球状の黒鉛が析出した機械的性質に優れた組織にすることが可能となる。
【０００７】
また上記第２の特徴による半溶融成形用鉄−炭素系合金によれば、上記第１の特徴による作用効果に加えて、ＣａとＣｅの何れか１種若しくは両方をそこに示される成分組成で含有させることにより、過剰な量を添加することなく必要十分な少量にて、半溶融成形に供する素材としての鉄−炭素系合金の白銑化を一層効果的に促進させることができ、よってまたデンドライトの微細化を一層効果的に促進させることができる。従って半溶融状態の材料の型空間への注入の際における充填不良、固液分離、空気の巻き込み等を一層効果的に低減することが可能となる。
また上記ＣａとＣｅの何れか１種若しくは両方をそこに示される成分組成で含有させることにより、半溶融成形の際における凝固組織の白銑化を一層促進させて、機械的性質の劣化原因となる共晶状や片状の黒鉛の晶出を更に効果的に防止することが可能となる。
また上記ＣａとＣｅの何れか１種若しくは両方をそこに示される成分組成で含有させることにより、半溶融成形により得られた成形体を黒鉛化熱処理する場合において、白銑の塊状黒鉛化を一層促進させることが可能となる。
【０００８】
また上記第３の特徴による半溶融成形法によれば、上記第１又は第２の特徴に示す半溶融成形用鉄−炭素系合金が加熱され、液相と固相とが共存した半溶融状態で型空間に充填され、加圧状態で凝固される。その際、半溶融状態から凝固に至るまでに要する時間が２秒以上かかる厚肉の部位には、型内への充填完了時において７．０ＭＰａ以上の圧力が加わる。このような条件で金型等の型内への射出等の注入条件を整えることで、成形体の厚肉部における鋳巣の発生を非常に効果的に抑制することができる。これにより成形体の機械的性質を良好にすることができる。
【０００９】
また上記第４の特徴による半溶融成形体によれば、上記第１又は第２の特徴に示す半溶融成形用鉄−炭素系合金が、上記第３の特徴による半溶融成形法で加工された後、８５０〜１０００℃の温度、３０〜６０分の保持時間で黒鉛化熱処理されることによって、黒鉛粒径が６０μｍ以下の微細で、且つ球状化率が７０％以上の内部組織からなる鉄−炭素系の半溶融成形体とされる。よってこの半溶融成形体によれば内部欠陥の少ない球状化黒鉛鋳鉄として優れた機械的性質を保有することができる。
【００１０】
次に本発明の半溶融成形用鉄−炭素系合金、及び半溶融成形体に含まれる各成分元素の含有範囲の限定理由について、以下に説明する。なお成分組成は全て重量％で示す。
Ｃの含有量は２．００〜３．００％とする。
Ｃが２．００％未満の場合には成形に必要な半溶融温度を高くする必要があり、金型等の型への熱負荷が大きく、金型寿命が短くなる。
一方、Ｃが３．００％を超えると、半溶融成形用の素材としての合金組織中及び半溶融成形による凝固組織中での共晶状黒鉛、片状黒鉛の量が多くなり、機械的性質が低下するので、好ましくない。
Ｃの含有量は、好ましくは２．１０〜２．５０％とするのがよい。
【００１１】
Ｓｉの含有量は１．５０〜３．００％とする。
Ｓｉが１．５０％未満では、半溶融成形後における熱処理において、白銑の黒鉛化がし難く、長時間の保持が必要となるので、工業的に好ましくない。
一方、Ｓｉが３．００％を超えると、シリコフェライトの生成により、成形体の靱性が低下するので、好ましくない。
Ｓｉの含有量は、好ましくは１．８０〜２．８０％とするのがよい。
【００１２】
加えて、炭素当量（Ｃ％＋１／３Ｓｉ％）が２．５０〜３．５０％とする。
炭素当量が２．５０％未満では、成形に必要な半溶融温度を高くする必要があり、金型等の型への熱負荷が大きく、金型寿命が短くなる。
一方、炭素当量が３．５０％を超えると、半溶融成形用の素材としての合金組織中及び半溶融成形による凝固組織中での共晶状黒鉛、片状黒鉛の量が多くなり、機械的性質が低下するので好ましくない。
炭素当量は、好ましくは２．８０〜３．２０％とする。
【００１３】
Ｍｇの含有量は０．０１５〜０．０３５％とする。
Ｍｇを含有させる理由は次の（１）、（２）、（３）からなる。
（１）．Ｍｇは鋳鉄において白銑化を助長する元素である。これによって半溶融成形に供する素材としての鉄−炭素系合金の白銑化を促進し、またデンドライトの微細化に寄与する。また半溶融成形の際における液相の凝固過程において組織の白銑化を助長し、機械的性質の劣化原因となる共晶状黒鉛、片状黒鉛の晶出を防止する。
（２）．Ｍｇは鋳鉄における溶融状態での粘性を高める元素である。よって半溶融成形の際に半溶融状態の材料を金型等の型空間にプランジャー等によって充填する場合、注入される材料の流れが層流になり易く、整然と充填され易くなり、空気等の巻き込みを防止することができる。
（３）．Ｍｇは白銑の黒鉛化の際に、得られる塊状黒鉛をより球状化させることができる。また得られる黒鉛の微細化を促進する。
【００１４】
上記（１）、（２）の理由については、一般的に溶湯にＭｇ処理を施して球状黒鉛鋳鉄を製造する場合にはむしろ欠点となるのであるが、半溶融成形関しては利点となる。そしてその効果を得るＭｇの量については、前記球状黒鉛鋳鉄を製造する場合よりも少ない量で必要十分となる。その理由は、半溶融の場合、Ｍｇは液相に偏析するため、Ｍｇの量は成形時点での液相の量（全体の４０〜６０％）に対して必要な量さえあればよいことによる。
即ち、本発明ではＭｇの含有量は０．０１５〜０．０３５％としている。
０．０１５％未満では白銑化効果が十分ではなく、半溶融成形の際に厚肉部に黒鉛が晶出し易くなる。また半溶融成形後の成形体の黒鉛化熱処理の際の効果が薄い。
一方、０．０３５％を超えると、Ｍｇ酸化物の巻き込み等の問題が生じて成形体の機械的強度を劣化させるおそれがある。
Ｍｇの含有量は、好ましくは０．０２０〜０．０３５％とする。
【００１５】
前記Ｍｇを含有することで、半溶融成形の際に液相部の粘性が高まり、その結果、半溶融成形中に液相だけが先に流れることなく、固相と液相とが均一に流動し易くなり、固相と液相との分離を防止することができる。
更にその後、液相部が共晶凝固する際、Ｍｇによる白銑化傾向が大きいため、厚肉部における片状黒鉛や共晶状黒鉛等の黒鉛の晶出が防がれる。また白銑化して得られたレデブライト組織も微細化する。
【００１６】
上記理由（３）に関し、一般に鋳鉄の半溶融成形により白銑化した凝固成形体を８５０℃以上の温度で保持して黒鉛化させた場合、その黒鉛形状は星形または塊状になることが知られている。
本発明の場合はＭｇを含有するため、黒鉛化熱処理による黒鉛の形状は星形や塊状からより球状に近くなる。更に半溶融成形により凝固した成形体のレデブライト組織は微細なため、析出する黒鉛も微細で粒数が多くなる。
【００１７】
上記Ｍｇに加えて、Ｃａ、Ｃｅの何れか一方若しくは両方を含有させることができる。その場合の含有量は、例えばＣａの場合で０．００５〜０．０５０％、Ｃｅの場合で０．００５〜０．０２０％とすることができる。
Ｃａ、ＣｅはＭｇと同様の作用を与えるものとして、上記理由の（１）、（２）、（３）に述べた作用効果を奏する。
ただしＣａ、Ｃｅは安定して溶湯中に添加することが困難であり、また少しの量の違いにより白銑化の効果が大きく異なってくるため、Ｍｇとの併用が望ましい。
【００１８】
次に上記した組成を有する半溶融成形用鉄−炭素系合金を半溶融成形する場合に、厚肉部を有する成形体であっても鋳巣やその他の欠陥が少なく、また成形体の組織が機械的性質に優れた組織となるよう成形することができる半溶融成形法について説明する。
一般に半溶融成形法では、成形時に固相が存在するため、溶湯を鋳込む通常の鋳造法に比べて、凝固収縮による鋳巣の発生は少ないと言われている。
しかしながら上記凝固収縮による鋳巣はゼロになるわけではなく、特に厚肉部の最終凝固部付近において発生し易く、機械的性質の劣化、気密性等で問題となることがあった。
一般的に鋳巣を防止するためには凝固終了が遅い部分に押湯を設置し、指向性凝固を促進することが有効であるが、成形体の形状により制限を受けることが多かった。
そこで本発明者は、鉄−炭素系合金について、種々の方案、射出条件による実験と、半溶融成形の際の半溶融物の流動の解析、及び凝固過程の解析を繰り返した結果、凝固終了までに要する時間が２秒以上かかる厚肉部に具体的に鋳巣が発生し易いこと、及び半溶融物の金型内への充填時における加圧の程度をうまく制御することで、厚肉部等における鋳巣を制御することができることを見出した。
【００１９】
即ち、本発明者は鉄−炭素系合金の半溶融成形法に関して、半溶融材料の金型への充填完了時点において、凝固終了までに２秒以上かかる厚肉部に対して、７．０ＭＰａ以上の圧力が加わるように、充填材料に対する射出条件等の、加圧条件を設定することにより、この種の材料の半溶融成形において厚肉を有する成形体であっても、著しく鋳巣を減少させることができることを見出した。
【００２０】
金型への充填完了から凝固終了までに要する時間が２秒以上要する部位では、金型に接する外周部からの凝固収縮及び温度低下による収縮の量が無視できなくなり、鋳巣が発生するものと考えられる。従って、このような部位に対しては指向性凝固となるように押し湯部を設けることが望ましい訳である。しかし、そのようにしなくとも、金型への充填完了時にゲート等を通じて、７．０ＭＰａの圧力が前記凝固終了までに２秒以上要する部位に加わるようにして、加圧することで、前記厚肉の部位に鋳巣が発生するのを著しく減少させることができるのである。この場合、例えゲート部等が前記厚肉の部位よりも先に凝固を完了することがあっても、その厚肉の部位の鋳巣の発生防止効果を発揮するのである。
【００２１】
以上のようにして半溶融成形されてなる成形体は、空気の巻き込み、厚肉部の鋳巣もなく、組織は白鋳鉄である。この成形体を８５０〜１０００℃で３０〜６０分保持する黒鉛化熱処理を施すことで、粒径が６０μｍ以下で、球状化率が７０％以上の球状黒鉛を有する組織とすることができる。また前記黒鉛化熱処理前に、焼入れ等により基地をマルテンサイト組織とした後、該黒鉛化熱処理を施すことにより、更に黒鉛の微細化が可能である。この黒鉛組織を有する成形体は高強度、高靭性で良好な機械的性質を有するものである。また黒鉛は微細で均一なため、優れた加工性を示す。
【００２２】
【実施例】
（第１実施例）
実施例１〜８と比較例１〜９について、表１に示す各成分（全て重量％で示す）を有する半溶融成形用鉄−炭素系合金をビレット状に鋳込んだ。この各ビレットを１２２０℃に加熱し、半溶融状態にして、図１にその概略を示す射出成形機を用いて金型空間に充填して、テストピースを半溶融成形した。
半溶融成形したテストピースの組織評価として、共晶黒鉛の有無、空気の巻き込み、酸化物の巻き込みについての評価をした。結果を表１に示す。
図１において、１は可動金型、２は固定金型、３はゲート、４は射出スリーブ、５はプランジャー、６は半溶融ビレット、７は金型空間、８は半溶融ビレット６の挿入口である。
得られる成形体は図２に示すような断面形状を持ち、斜線で示す領域Ｄが凝固終了までに２秒以上かかる部位である。
【００２３】
【表１】
表１から明らかなように、第１実施例１〜８では、共晶黒鉛の発生、空気の巻き込み、Ｍｇ等の添加による酸化物の巻き込みによる欠陥は見られなかった。
一方、第１比較例１〜９は何れもＣ、Ｓｉ、及び炭素当量は本発明の範囲内であるが、第１比較例１〜６ではＭｇの含有量が０．０１５％未満で、何れも共晶黒鉛の発生があり、空気の巻き込み傾向があった。また第１比較例７〜９ではＭｇの含有量が０．０３５％を超えており、共晶黒鉛の発生、空気巻き込みは見られなかったが、酸化物の巻き込みが見られた。
【００２５】
（第２実施例）
Ｆｅ−２．３５％Ｃ−２．０４％Ｓｉ−０．０２２％Ｍｇを成分とした半溶融成形用鉄−炭素系合金をビレット状に鋳込んで半溶融成形用の素材とし、このビレットを１２２０℃に加熱して、半溶融状態とし、図１に示す射出成形機を用い、表２に示す加圧条件にてテストピースを成形して、厚肉部における鋳巣の有無を検査、評価した。評価を表２に示す。
なお加圧条件は、凝固終了までに２秒以上かかる部位Ｄに対して、金型内空間７への充填完了時における加圧が、それぞれ５．５〜８．０ＭＰａとなるように設定した。
【００２６】
【表２】
表２から明らかなように、凝固終了までに２秒以上かかる部位Ｄに対して、金型内空間７への充填完了時における加圧を７．０ＭＰａ以上にした場合には、鋳巣は生じなかった。反面、６．５ＭＰａ以下の場合は鋳巣が生じた。
【００２８】
（第３実施例）
第２実施例１、２、３を半溶融成形後に９５０℃で５０分保持して黒鉛化熱処理を施した。
一方、第２実施例１、２、３と同様の成分組成で、Ｍｇを含有しない比較例について、それぞれ同様の条件で半溶融成形及びその後の黒鉛化処理を施し、得られた各試料の組織を比較した。
その結果、第２実施例１、２、３のものは組織中に黒鉛が微細に且つ球状化して存在しており、比較例においてはそのようになっていないことが明らかに観察された。
【００２９】
【発明の効果】
本発明は以上の構成、作用よりなり、請求項１に記載の半溶融成形用に供される鉄−炭素系合金によれば、成分組成が重量％で、Ｃ：２．００〜３．００％、Ｓｉ：１．５０〜３．００％、炭素当量（Ｃ＋１／３Ｓｉ）：２．５０〜３．５０％、Ｍｇ：０．０１５〜０．０３５％を含有すると共に、残部が実質的にＦｅからなり、且つ組織を白銑化させてあるので、
半溶融成形における型の熱負担を軽減してその寿命を長くすることができると共に、半溶融加工の際に得られる成形体に鋳巣やその他の欠陥が少なく且つ粗大なデンドライト組織や共晶状或いは片状の黒鉛が生じない白銑の凝固組織を可能にすることができる。更に半溶融成形後の熱処理により、成形体の組織を微細な塊状或いは球状の黒鉛が析出した機械的性質に優れた組織にすることが可能となる。
また請求項２に記載の半溶融成形用に供される鉄−炭素系合金によれば、上記請求項１に記載の構成による効果に加えて、ＣａとＣｅの何れか１種若しくは両方を、重量％でＣａ：０．００５〜０．０５０％、Ｃｅ：０．００５〜０．０２０％含有させるので、
Ｃａ、Ｃｅの過剰な量を添加することなく必要十分な少量にて、半溶融成形に供する素材としての鉄−炭素系合金の白銑化を一層効果的に促進させることができ、よってまたデンドライトの微細化を一層効果的に促進させることができる。従って半溶融状態の材料の型空間への注入の際における充填不良、固液分離、空気の巻き込み等を一層効果的に低減することが可能となる。
また上記ＣａとＣｅの何れか１種若しくは両方をそこに示される成分組成で含有させることにより、半溶融成形の際における凝固組織の白銑化を一層促進させて、機械的性質の劣化原因となる共晶状や片状の黒鉛の晶出を更に効果的に防止することが可能となる。
また上記ＣａとＣｅの何れか１種若しくは両方をそこに示される成分組成で含有させることにより、半溶融成形により得られた成形体を黒鉛化熱処理する場合において、白銑の塊状黒鉛化を一層促進させることが可能となる。
また請求項３に記載の半溶融成形法によれば、請求項１又は２に記載の半溶融成形用鉄−炭素系合金を固相と液相とが共存した半溶融状態にして金型等の型空間に充填すると共に、該充填された材料の型空間内での部位のうち凝固終了に要する時間が２秒以上かかる部位に対して７．０ＭＰａ以上の圧力が充填完了時において加わるように、前記充填された材料に圧力を加えるので、
凝固終了までに２秒以上の時間がかかるような成形体の厚肉部においても、鋳巣の発生を非常に効果的に抑制することができる。よって厚肉部のある成形体であっても、その機械的性質を十分に良好にすることができる。
また請求項４に記載の半溶融成形体によれば、請求項１又は２に記載の半溶融成形用鉄−炭素系合金を請求項３の半溶融成形法を施して成形した後、８５０〜１０００℃の温度、３０〜６０分の保持時間で黒鉛化熱処理を施すことにより、黒鉛粒径が６０μｍ以下で、球状化率が７０％以上の球状黒鉛を有する内部組織としたので、
この半溶融成形体によれば内部欠陥の少ない球状化黒鉛鋳鉄として優れた機械的性質を保有することができる。
また上記黒鉛化熱処理前に、焼入れ等により基地をマルテンサイト組織とした後、該黒鉛化熱処理を施すことにより、更に黒鉛の微細化が可能である。
【図面の簡単な説明】
【図１】本発明の半溶融成形法に用いることができる射出成形機の概略断面である。
【図２】図１の射出成形機で得られる半溶融成形体の例を示す断面図である。
【符号の説明】
１ 可動金型
２ 固定金型
３ ゲート
４ 射出スリーブ
５ プランジャー
６ 半溶融ビレット
７ 金型空間
８ 挿入口
Ｄ 凝固終了までに２秒以上かかる部位[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an iron-carbon alloy for semi-solid forming, a semi-solid forming method and a semi-solid formed body using the same.
[0002]
[Prior art]
A semi-solid molding method is being applied in which cast iron of a hypoeutectic component is heated to a semi-molten state and molded. In this case, the hypoeutectic cast iron used for the material is desirably white pig iron. The reason is that, even with cast iron of the same composition, the dendrite is finer in cast iron made into white iron, so the diameter of the solid phase in the semi-molten state is small, and the mechanical properties of the obtained compact are low. Excellent, and when using graphitized cast iron, because it melts from around graphite when heated to a semi-molten temperature, the solid phase and the liquid phase become non-uniform, as a result, even when heated to the same temperature The reason for this is that the liquid phase is more likely to flow out as compared with white iron cast iron, and thus it becomes more difficult to maintain the shape of a semi-molten billet or the like to be subjected to semi-solid molding.
On the other hand, even when the hypoeutectic cast iron is used as white iron, if the dendrite structure remains in a state at a semi-molten temperature, the viscosity is high, poor filling into the mold space, the solid phase and the liquid phase There is a problem that the separation of the particles easily occurs.
As one means for solving this problem, for example, the inventions disclosed in Japanese Patent No. 3096176 and Japanese Patent Application Laid-Open No. 8-90191 are disclosed. In these disclosed inventions, with regard to die casting of white cast iron or spheroidal graphite cast iron, the gate area to the mold space is set to be 1/10 or less of the plunger pressurized area, so that the dendrite structure can pass through the gate well. There is provided a technical method that is designed to destroy the data.
Further, as another method of semi-solid molding of cast iron, there is a method in which the structure of a compact at the time of solidification by semi-solid molding is a white pig structure, and thereafter, the compact is heat-treated to graphitize the white pig iron. In this method, the heat treatment causes the graphite to be close to a lump, so that mechanical properties comparable to spheroidal graphite cast iron may be obtained.
[0003]
[Problems to be solved by the invention]
However, in the technical method disclosed in the above-mentioned Patent No. 3096176 and Japanese Patent Application Laid-Open No. 8-90191, since the gate is excessively narrowed, a molded body having a thick portion is formed without internal defects such as air entrapment and a void. There was a problem that it was difficult. The reason is that in the above technical method, the gate portion having a very small diameter solidifies faster than the thick portion in the mold, and therefore, the external portion adds to the unsolidified molten metal in the thick portion through the gate portion. This is because it becomes difficult to apply pressure and a porosity is likely to occur. Also, because the gate diameter is very narrow, turbulence is likely to occur at the time of injection into the mold, and air entrapment is likely to occur.
On the other hand, in the case of a method in which the structure of the compact at the time of solidification by the above-mentioned semi-solid molding is made into white iron and the white iron is graphitized by a subsequent heat treatment, a thick portion of the semi-solid molded body is formed. In this case, since the cooling rate during solidification is slow, flake or eutectic graphite often crystallizes out.As a result, it is difficult to change the shape of these crystallized graphite into a lump even in the subsequent heat treatment. However, there is a problem that the mechanical properties may be rather deteriorated.
[0004]
Therefore, the present invention solves the above-mentioned problems of the conventional semi-solid molding using cast iron, and a semi-solid iron-carbon alloy for semi-solid molding capable of obtaining a molded body having good mechanical properties and other properties in the semi-solid molding. The task is to provide It is another object of the present invention to provide a semi-solid molding method and a semi-solid molded body capable of obtaining good mechanical properties and other properties by using the iron-carbon alloy for semi-solid molding.
[0005]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the iron-carbon alloy for semi-solid molding of the present invention is an iron-carbon alloy used for semi-solid molding and has a component composition of% by weight and C: 2.00. 3.00%, Si: 1.50 to 3.00%, carbon equivalent (C + 1 / 3Si): 2.50 to 3.50%, Mg: 0.015 to 0.035%, and the balance Is substantially made of Fe, and has a first feature that the structure is made into white iron.
In addition, the iron-carbon alloy for semi-solid molding of the present invention, in addition to the first feature, contains one or both of Ca and Ce by weight% of Ca: 0.005 to 0.050%. , Ce: 0.005 to 0.020%. Further, the semi-solid molding method of the present invention is characterized in that the iron-carbon alloy for semi-solid molding according to the first or second aspect is formed into a semi-molten state in which a solid phase and a liquid phase coexist and a mold such as a mold is formed. In addition to filling the space, a pressure of 7.0 MPa or more is applied to a portion of the portion of the filled material in the mold space that takes 2 seconds or more to complete the solidification at the time of the completion of the filling. A third feature is that pressure is applied to the filled material. Further, the semi-solid molded body of the present invention is obtained by subjecting the semi-solid-forming iron-carbon alloy according to the first or second feature to a semi-solid molding method according to the third feature, and then forming the same. By performing the graphitization heat treatment at a temperature of 850 to 1000 ° C. and a holding time of 30 to 60 minutes, the internal structure having a spherical graphite having a graphite particle diameter of 60 μm or less and a spheroidization rate of 70% or more was described. 4.
[0006]
According to the iron-carbon alloy for semi-solidification according to the first feature, the temperature required to semi-molten the material (the semi-molten temperature of the material) is too high due to the component composition of C and Si shown therein. It can be suppressed so that it does not become. As a result, the heat load of a mold such as a mold used for semi-solid molding is reduced, and the life can be prolonged.
Further, by adding Mg in the indicated content in addition to the composition of C and Si, an iron-carbon based material to be subjected to semi-solid forming while preventing entrapment of an oxide accompanying oxidation of a molten metal and the like. The alloy can be turned into white iron as necessary and sufficiently, and can be adjusted to be sufficiently fine by suppressing coarsening of dendrite. Thereby, it is possible to eliminate poor filling and separation between a solid phase and a liquid phase when the material is injected into the mold space in a semi-molten state. Further, by adding Mg, the viscosity of the molten metal can be increased to reduce the entrapment of air during injection.
Further, the component composition of C, Si, and Mg can turn the solidified structure during semi-solid molding into white iron, and prevent crystallization of eutectic or flake graphite that causes deterioration of mechanical properties. it can.
Further, when the molded body obtained by semi-solid molding is subjected to a graphitization heat treatment, the composition of C, Si, and Mg can promote the massization of white pig iron, and further, the spheroidization and miniaturization thereof.
Therefore, according to the iron-carbon alloy for semi-solid molding according to the first feature, the heat load of the mold in semi-solid molding can be reduced and the life thereof can be prolonged, and the molding obtained during semi-solid molding can be achieved. It is possible to enable a solidified structure of white pig iron that has few voids and other defects in the body and does not generate a coarse dendrite structure or eutectic or flake graphite. Further, by the heat treatment after the semi-solid molding, it is possible to make the structure of the molded body a structure excellent in mechanical properties in which fine massive or spherical graphite is precipitated.
[0007]
Further, according to the iron-carbon alloy for semi-solid forming according to the second feature, in addition to the function and effect according to the first feature, one or both of Ca and Ce are used in a component composition shown therein. By containing, in a necessary and sufficient small amount without adding an excessive amount, the iron-carbon alloy as a material to be subjected to semi-solid molding can be more effectively promoted to white iron, and Dendrite miniaturization can be more effectively promoted. Therefore, it is possible to more effectively reduce poor filling, solid-liquid separation, entrainment of air, and the like when the semi-molten material is injected into the mold space.
Further, by containing one or both of the above Ca and Ce with the component composition shown therein, the solidification structure at the time of semi-solid molding is further promoted to form a white iron, which causes deterioration of mechanical properties. The crystallization of eutectic or flaky graphite can be more effectively prevented.
In addition, when one or both of the above Ca and Ce are contained in the component composition shown there, when the molded body obtained by the semi-solid molding is subjected to the graphitization heat treatment, the mass graphitization of white iron is further enhanced. It can be promoted.
[0008]
According to the semi-solid forming method according to the third aspect, the iron-carbon alloy for semi-solid forming described in the first or second aspect is heated, and the semi-molten state in which a liquid phase and a solid phase coexist. Is filled in the mold space and solidified in a pressurized state. At this time, a pressure of 7.0 MPa or more is applied to a thick portion where the time required from solid state to solidification takes 2 seconds or more at the time of completion of filling into the mold. By adjusting the injection conditions such as injection into a mold such as a mold under such conditions, it is possible to very effectively suppress the occurrence of a cavity in a thick portion of a molded body. Thereby, the mechanical properties of the molded body can be improved.
[0009]
According to the semi-solid formed body according to the fourth aspect, the iron-carbon alloy for semi-solid forming according to the first or second aspect is processed by the semi-solid forming method according to the third aspect. After that, it is subjected to a graphitization heat treatment at a temperature of 850 to 1000 ° C. and a holding time of 30 to 60 minutes, so that an iron-containing fine structure having a graphite particle size of 60 μm or less and a spheroidization ratio of 70% or more is formed. It is a carbon-based semi-solid molded body. Therefore, according to this semi-solid molded body, excellent mechanical properties can be maintained as spheroidized graphite cast iron having few internal defects.
[0010]
Next, the reasons for limiting the content ranges of the respective component elements contained in the semi-solid-formed iron-carbon alloy and the semi-solid formed body of the present invention will be described below. In addition, all component compositions are shown by weight%.
The content of C is 2.00 to 3.00%.
When C is less than 2.00%, it is necessary to increase the half-melting temperature necessary for molding, and the heat load on a mold such as a mold is large, and the mold life is shortened.
On the other hand, if C exceeds 3.00%, the amount of eutectic graphite and flake graphite in the alloy structure as a material for semi-solid molding and in the solidified structure by semi-solid molding increases, and the mechanical properties increase. Is undesirably reduced.
The content of C is preferably set to 2.10 to 2.50%.
[0011]
The content of Si is set to 1.50 to 3.00%.
If the Si content is less than 1.50%, in the heat treatment after the semi-solid molding, the white pig iron is hardly graphitized and needs to be maintained for a long time, which is not industrially preferable.
On the other hand, if the Si content exceeds 3.00%, the toughness of the molded body is reduced due to the formation of silicoferrite, which is not preferable.
The content of Si is preferably set to 1.80 to 2.80%.
[0012]
In addition, the carbon equivalent (C% + ／ Si%) is 2.50 to 3.50%.
If the carbon equivalent is less than 2.50%, it is necessary to increase the half-melting temperature required for molding, and the heat load on a mold such as a mold is large, and the mold life is shortened.
On the other hand, if the carbon equivalent exceeds 3.50%, the amount of eutectic graphite and flake graphite in the alloy structure as a material for semi-solid molding and in the solidified structure by semi-solid molding increases, and the mechanical equivalent increases. It is not preferable because properties are deteriorated.
The carbon equivalent is preferably set to 2.80 to 3.20%.
[0013]
The content of Mg is 0.015 to 0.035%.
The reason for containing Mg is as follows (1), (2) and (3).
(1). Mg is an element that promotes white iron in cast iron. This promotes the conversion of iron-carbon based alloys to white iron as a raw material to be subjected to semi-solid molding, and contributes to dendrite miniaturization. In addition, it promotes the formation of white iron in the structure during the solidification process of the liquid phase during semi-solid molding, and prevents the crystallization of eutectic graphite and flaky graphite which cause deterioration of mechanical properties.
(2). Mg is an element that increases the viscosity of the cast iron in a molten state. Therefore, when filling a semi-molten state material into a mold space such as a mold by a plunger or the like at the time of semi-solid molding, the flow of the injected material tends to be laminar, and it is easy to be filled in orderly, so that air and the like can be easily filled. Entanglement can be prevented.
(3). Mg can make the obtained massive graphite more spherical when the white iron is graphitized. Further, it promotes miniaturization of the obtained graphite.
[0014]
The reasons (1) and (2) are rather disadvantageous in the case of producing a spheroidal graphite cast iron by generally performing Mg treatment on a molten metal, but it is advantageous in terms of semi-solid molding. As for the amount of Mg to obtain the effect, a smaller amount than in the case of producing the spheroidal graphite cast iron is necessary and sufficient. The reason is that, in the case of semi-molten, Mg segregates into the liquid phase, so that the amount of Mg only needs to be an amount necessary for the amount of the liquid phase at the time of molding (40 to 60% of the whole). .
That is, in the present invention, the content of Mg is set to 0.015 to 0.035%.
If it is less than 0.015%, the effect of turning white iron is not sufficient, and graphite tends to crystallize in a thick portion during semi-solid molding. Also, the effect of the graphitizing heat treatment of the compact after semi-solid molding is weak.
On the other hand, if it exceeds 0.035%, problems such as entrainment of Mg oxide may occur, and the mechanical strength of the molded body may be deteriorated.
The content of Mg is preferably set to 0.020 to 0.035%.
[0015]
The inclusion of Mg increases the viscosity of the liquid phase during semi-solid molding, and as a result, the solid phase and liquid phase flow evenly during semi-solid molding without the liquid phase flowing first. And the separation of the solid phase and the liquid phase can be prevented.
Further, thereafter, when the liquid phase portion undergoes eutectic solidification, the tendency of white iron formation by Mg is large, so that crystallization of graphite such as flake graphite and eutectic graphite in the thick portion is prevented. In addition, the redebrite structure obtained by turning to white iron is also refined.
[0016]
Regarding the above reason (3), it is generally known that when a solidified compact formed into white iron by semi-solid molding of cast iron is graphitized while being held at a temperature of 850 ° C. or higher, the graphite shape becomes star-shaped or massive. Have been.
In the case of the present invention, since Mg is contained, the shape of the graphite by the graphitization heat treatment becomes closer to a sphere than a star or a lump. Furthermore, since the redebrite structure of the compact solidified by the semi-solid molding is fine, the precipitated graphite is fine and the number of grains is large.
[0017]
In addition to the above Mg, one or both of Ca and Ce can be contained. The content in that case can be, for example, 0.005 to 0.050% for Ca and 0.005 to 0.020% for Ce.
Ca and Ce have the same effects as Mg and have the effects described in (1), (2) and (3) above.
However, it is difficult to stably add Ca and Ce to the molten metal, and a slight difference in the amount greatly changes the effect of white pig iron, so that it is desirable to use together with Mg.
[0018]
Next, when the semi-solid-forming iron-carbon alloy having the above composition is semi-solid molded, even if the molded body has a thick portion, there are few voids and other defects, and the structure of the molded body is small. A semi-solid molding method capable of forming a structure having excellent mechanical properties will be described.
Generally, in the semi-solid molding method, since a solid phase is present at the time of molding, it is said that there is less porosity due to solidification shrinkage than in a normal casting method in which a molten metal is cast.
However, the voids due to the above-mentioned solidification shrinkage are not always zero, and are likely to occur particularly near the final solidification part of a thick part, which may cause problems such as deterioration of mechanical properties and airtightness.
In general, it is effective to install a feeder at a portion where the solidification is completed late to promote directional solidification in order to prevent cavities, but it is often limited by the shape of the formed body.
Therefore, the present inventor, for iron-carbon based alloys, as a result of repeating various experiments and experiments under injection conditions, analyzing the flow of the semi-molten material during semi-solid molding, and analyzing the solidification process, until the solidification was completed. It takes 2 seconds or more for the thick part, which is likely to cause concrete cavities, and by appropriately controlling the degree of pressurization when filling the semi-molten material into the mold, the thick part It has been found that it is possible to control the casting cavities in such as.
[0019]
That is, the inventor of the present invention relates to a semi-solid molding method of an iron-carbon alloy, at the time of completion of filling of a semi-molten material into a mold, for a thick portion which takes 2 seconds or more to complete solidification, 7.0 MPa or more. By setting pressurizing conditions such as injection conditions for the filling material so that the pressure is applied, even in the case of a molded body having a thick wall in the semi-solid molding of this kind of material, the voids are significantly reduced. I found that I can do it.
[0020]
In areas where the time required from the completion of filling into the mold to the completion of solidification is 2 seconds or more, the amount of solidification shrinkage from the outer peripheral portion in contact with the mold and shrinkage due to temperature decrease cannot be ignored, and cavities are generated. Conceivable. Therefore, it is desirable to provide a feeder in such a portion so as to achieve directional solidification. However, even if it does not do so, by applying a pressure of 7.0 MPa through a gate or the like at the time of completion of filling into the mold so as to apply a pressure of 2 seconds or more to the end of the solidification, the pressure is increased, and the thick wall is removed. It is possible to significantly reduce the occurrence of cavities at the site. In this case, even if the gate portion or the like completes solidification earlier than the thick portion, the effect of preventing the formation of cavities in the thick portion is exhibited.
[0021]
The compact obtained by semi-solid molding as described above has no air entrapment, no porosity in the thick portion, and the structure is white cast iron. By subjecting the formed body to a graphitization heat treatment at 850 to 1000 ° C. for 30 to 60 minutes, a structure having spherical graphite with a particle size of 60 μm or less and a spheroidization rate of 70% or more can be obtained. Further, before the graphitization heat treatment, the base is made into a martensite structure by quenching or the like, and then the graphitization heat treatment is performed, so that the graphite can be further refined. The molded body having the graphite structure has high strength, high toughness and good mechanical properties. In addition, graphite is fine and uniform, and exhibits excellent workability.
[0022]
【Example】
(First embodiment)
In Examples 1 to 8 and Comparative Examples 1 to 9, iron-carbon alloys for semi-solid molding having the components shown in Table 1 (all shown in% by weight) were cast into billets. Each of the billets was heated to 1220 ° C. to be in a semi-molten state, and was filled in a mold space using an injection molding machine schematically shown in FIG. 1, and a test piece was semi-molten molded.
As the structure evaluation of the semi-solid molded test piece, the presence or absence of eutectic graphite, air entrainment, and oxide entrainment were evaluated. The results are shown in Table 1.
In FIG. 1, 1 is a movable mold, 2 is a fixed mold, 3 is a gate, 4 is an injection sleeve, 5 is a plunger, 6 is a semi-molten billet, 7 is a mold space, and 8 is insertion of a
The obtained molded body has a cross-sectional shape as shown in FIG. 2, and a region D indicated by oblique lines is a region where it takes 2 seconds or more to complete solidification.
[0023]
[Table 1]
As is clear from Table 1, in Examples 1 to 8, no defects were found due to generation of eutectic graphite, entrapment of air, and entrapment of oxides due to addition of Mg and the like.
On the other hand, the first comparative examples 1 to 9 all have C, Si, and carbon equivalents within the scope of the present invention, but the first comparative examples 1 to 6 have a Mg content of less than 0.015%, Also, eutectic graphite was generated and air was entrapped. In addition, in the first comparative examples 7 to 9, the content of Mg exceeded 0.035%, and generation of eutectic graphite and entrainment of air were not observed, but entrapment of oxide was observed.
[0025]
(Second embodiment)
An iron-carbon alloy for semi-solid molding containing Fe-2.35% C-2.04% Si-0.022% Mg as a component is cast into a billet to form a material for semi-solid molding. The test piece was heated to 1220 ° C. to be in a semi-molten state, and a test piece was molded using the injection molding machine shown in FIG. did. The evaluation is shown in Table 2.
The pressurizing conditions were set so that the pressurization at the time of completion of filling the
[0026]
[Table 2]
As is clear from Table 2, when the pressure at the time of completion of the filling into the
[0028]
(Third embodiment)
The second examples 1, 2, and 3 were subjected to graphitization heat treatment at 950 ° C. for 50 minutes after semi-solid molding.
On the other hand, for the comparative example having the same component composition as that of the second examples 1, 2, and 3 and containing no Mg, the semi-solid molding and the subsequent graphitization treatment were performed under the same conditions, and the structure of each of the obtained samples was obtained. Were compared.
As a result, it was clearly observed that graphite was finely and spheroidized in the structures of the second examples 1, 2, and 3 and not so in the comparative example.
[0029]
【The invention's effect】
The present invention has the above-mentioned constitution and function, and according to the iron-carbon alloy used for semi-solid molding according to claim 1, the component composition is% by weight and C: 2.00 to 3.00. %, Si: 1.50 to 3.00%, carbon equivalent (C + ／ Si): 2.50 to 3.50%, Mg: 0.015 to 0.035%, and the balance is substantially the same. Since it is made of Fe and the structure is made into white iron,
In addition to reducing the heat load on the mold in semi-solid molding, the life of the mold can be extended, and the molded product obtained during semi-solid processing has few cavities and other defects and a coarse dendrite structure or eutectic structure. Alternatively, a solidified structure of white iron in which flake graphite is not generated can be made possible. Further, by the heat treatment after the semi-solid molding, it is possible to make the structure of the molded body a structure excellent in mechanical properties in which fine massive or spherical graphite is precipitated.
Further, according to the iron-carbon alloy used for semi-solid molding according to claim 2, in addition to the effect of the configuration according to claim 1, one or both of Ca and Ce are used. Since the content of Ca is 0.005 to 0.050% and the content of Ce is 0.005 to 0.020% by weight,
A necessary and sufficient small amount without adding excessive amounts of Ca and Ce can more effectively promote white ironing of iron-carbon based alloy as a raw material to be subjected to semi-solid molding, and thus also dendrite Can be more effectively promoted. Therefore, it is possible to more effectively reduce poor filling, solid-liquid separation, entrainment of air, and the like when the semi-molten material is injected into the mold space.
Further, by containing one or both of the above Ca and Ce with the component composition shown therein, the solidification structure at the time of semi-solid molding is further promoted to form a white iron, which causes deterioration of mechanical properties. The crystallization of eutectic or flaky graphite can be more effectively prevented.
In addition, when one or both of the above Ca and Ce are contained in the component composition shown there, when the molded body obtained by the semi-solid molding is subjected to the graphitization heat treatment, the mass graphitization of white iron is further enhanced. It can be promoted.
According to the semi-solid molding method according to the third aspect, the iron-carbon alloy for semi-solid molding according to the first or second aspect is formed into a semi-molten state in which a solid phase and a liquid phase coexist, and a mold or the like is used. So that a pressure of 7.0 MPa or more is applied to a portion of the portion of the filled material in the mold space which takes 2 seconds or more to complete solidification at the time of completion of filling. , Applying pressure to the filled material,
Even in a thick portion of a molded body in which it takes 2 seconds or more to complete solidification, it is possible to very effectively suppress the occurrence of a cavity. Therefore, the mechanical properties of a molded body having a thick portion can be sufficiently improved.
According to the semi-solid molded article of the fourth aspect, the iron-carbon alloy for semi-solid molding of the first or second aspect is formed by performing the semi-solid molding method of the third aspect, and then subjected to 850 to 850. By performing a graphitization heat treatment at a temperature of 1000 ° C. and a holding time of 30 to 60 minutes, the internal structure has spherical graphite with a graphite particle diameter of 60 μm or less and a spheroidization rate of 70% or more.
According to this semi-solid molded body, excellent mechanical properties can be maintained as a spheroidized graphite cast iron having few internal defects.
Further, before the graphitization heat treatment, the matrix is made into a martensite structure by quenching or the like, and then the graphitization heat treatment is performed, so that the graphite can be further refined.
[Brief description of the drawings]
FIG. 1 is a schematic cross section of an injection molding machine that can be used in the semi-solid molding method of the present invention.
FIG. 2 is a sectional view showing an example of a semi-solid product obtained by the injection molding machine of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Movable mold 2
Claims (4)
Ｃ ： ２．００〜３．００％、
Ｓｉ ： １．５０〜３．００％、
炭素当量（Ｃ＋１／３Ｓｉ） ： ２．５０〜３．５０％、
Ｍｇ ： ０．０１５〜０．０３５％
を含有すると共に、残部が実質的にＦｅからなり、且つ組織を白銑化させてあることを特徴とする半溶融成形用鉄−炭素系合金。An iron-carbon alloy to be used for semi-solid molding, wherein the composition of the component is% by weight,
C: 2.00 to 3.00%,
Si: 1.50 to 3.00%,
Carbon equivalent (C + ／ Si): 2.50 to 3.50%,
Mg: 0.015 to 0.035%
, And the balance is substantially made of Fe, and the structure of the iron-carbon alloy for semi-solid forming is characterized by being made of white iron.
Ｃａ ： ０．００５〜０．０５０％、
Ｃｅ ： ０．００５〜０．０２０％
含有させることを特徴とする請求項１に記載の半溶融成形用鉄−炭素系合金。Any one or both of Ca and Ce, by weight% Ca: 0.005 to 0.050%,
Ce: 0.005 to 0.020%
The iron-carbon based alloy for semi-solid forming according to claim 1, wherein the alloy is contained.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010131635A (en) * | 2008-12-04 | 2010-06-17 | Nippon Steel Corp | Die-cast molding method for iron and die-cast molded body |
| WO2010103641A1 (en) * | 2009-03-12 | 2010-09-16 | 虹技株式会社 | Process for production of semisolidified slurry of iron-base alloy; process for production of cast iron castings by using the process, and cast iron castings |
| JP2013216950A (en) * | 2012-04-10 | 2013-10-24 | Nippon Chuzo Kk | Cast iron billet for thixocasting and method for producing the same |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010131635A (en) * | 2008-12-04 | 2010-06-17 | Nippon Steel Corp | Die-cast molding method for iron and die-cast molded body |
| WO2010103641A1 (en) * | 2009-03-12 | 2010-09-16 | 虹技株式会社 | Process for production of semisolidified slurry of iron-base alloy; process for production of cast iron castings by using the process, and cast iron castings |
| US8486329B2 (en) | 2009-03-12 | 2013-07-16 | Kogi Corporation | Process for production of semisolidified slurry of iron-base alloy and process for production of cast iron castings by using a semisolidified slurry |
| JP2013216950A (en) * | 2012-04-10 | 2013-10-24 | Nippon Chuzo Kk | Cast iron billet for thixocasting and method for producing the same |
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