JP4395385B2 - Gray cast iron - Google Patents

Gray cast iron Download PDF

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JP4395385B2
JP4395385B2 JP2004030683A JP2004030683A JP4395385B2 JP 4395385 B2 JP4395385 B2 JP 4395385B2 JP 2004030683 A JP2004030683 A JP 2004030683A JP 2004030683 A JP2004030683 A JP 2004030683A JP 4395385 B2 JP4395385 B2 JP 4395385B2
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cast iron
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gray cast
mpa
tensile strength
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法章 香取
省一 石井
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Hino Motors Ltd
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  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Description

本発明はねずみ鋳鉄材に関するものである。   The present invention relates to a gray cast iron material.

ねずみ鋳鉄は、生産性、耐磨耗性に優れているが引張強さが低いため、構造部品への適用が制約されている。そこで、例えば、車両のエンジンにおける吸気弁や排気弁を作動させるロッカアーム等の構造部品に対するねずみ鋳鉄の適用を容易に行い得るよう、ねずみ鋳鉄を高強度化することが行われており、この高強度化したねずみ鋳鉄としては、例えば、１．低炭素化や接種技術を用いたもの、２．合金添加により高強度化を計ったもの、がある。   Gray cast iron is excellent in productivity and wear resistance, but its tensile strength is low, so its application to structural parts is restricted. Therefore, for example, gray cast iron has been increased in strength so that it can be easily applied to structural parts such as rocker arms that operate intake valves and exhaust valves in a vehicle engine. Examples of converted gray cast iron include: 1. Using low carbonization or inoculation technology. Some have been made stronger by adding alloys.

なお、ねずみ鋳鉄の先行技術文献としては、例えば、特許文献１、特許文献２等がある。
特開２００２−１０５５８１号公報 特開２００３−２４７０１４号公報 In addition, as prior art documents of gray cast iron, for example, there are Patent Document 1, Patent Document 2, and the like.
JP 2002-105581 A JP 2003-247014 A

上述の高強度化したねずみ鋳鉄のうち、１．のねずみ鋳鉄では、原料を溶解する際に、鋼屑材を４０〜１００％と多量に使用し、加炭して鋳造するため、コストや生産性に問題がある。又、２．のねずみ鋳鉄では、薄肉部に炭化物の析出が生じやすく、炭化物の析出部は本来の要求された性質と大きく異なるため、通常のねずみ鋳鉄の引張強さは３５０ＭＰａ程度が限界であるという問題がある。   Among the above-mentioned high strength gray cast irons: Gray cast iron has a problem in cost and productivity because it uses a large amount of steel scrap material of 40 to 100% and carburizes and casts when melting the raw material. In addition, 2. In gray cast iron, carbide precipitation is likely to occur in the thin-walled portion, and the carbide precipitation portion is significantly different from the originally required properties, so there is a problem that the tensile strength of ordinary gray cast iron is limited to about 350 MPa. .

本発明は上述の実情に鑑み、硬度の大幅な上昇がない耐磨耗性に優れた、引張強さが４００ＭＰａ以上の生産性の良好なねずみ鋳鉄材を提供することを目的としてなしたものである。   In view of the above-mentioned circumstances, the present invention was made for the purpose of providing a gray cast iron material excellent in abrasion resistance without significant increase in hardness and good in productivity with a tensile strength of 400 MPa or more. is there.

請求項１のねずみ鋳鉄材は、重量比で、Ｃ：２．４〜２．８Ｗｔ％、Ｓｉ：２．３〜３．５Ｗｔ％、Ｍｎ：０．２〜０．８Ｗｔ％、Ｐ：≦０．１Ｗｔ％、Ｓ：≦０．１５Ｗｔ％、Ｃｕ：０．６〜１．４Ｗｔ％、Ｍｏ：≦０．５Ｗｔ％、Ｃｒ：≦０．３Ｗｔ％、残部はＦｅである化学成分を含有し、Ｓｉ／Ｃの比を０．９５以上とし、（Ｓｉ／Ｃ）／Ｃｕの比を１．５以下としたものである。 The gray cast iron material according to claim 1 is, by weight ratio, C: 2.4 to 2.8 Wt%, Si: 2.3 to 3.5 Wt%, Mn: 0.2 to 0.8 Wt%, P: ≦ 0. 0.1 Wt%, S: ≦ 0.15 Wt%, Cu: 0.6 to 1.4 Wt%, Mo: ≦ 0.5 Wt%, Cr: ≦ 0.3 Wt%, the balance contains a chemical component that is Fe , The ratio of Si / C is 0.95 or more, and the ratio of (Si / C) / Cu is 1.5 or less.

本発明の請求項１記載のねずみ鋳鉄材によれば、炭化物の析出が少なく、且つ硬度の大幅な上昇がない耐磨耗性に優れた、引張強さが４００ＭＰａ以上の生産性の良好な鋳鉄を得ることができる、という優れた効果を奏し得る。 According to gray cast iron material according to the first aspect of the present invention, less carbide precipitation, and significant increase in hardness and excellent no abrasion resistance, good tensile strength is greater than or equal productivity 400MPa cast iron It is possible to obtain an excellent effect that can be obtained.

以下、本発明の実施の形態を図示例と共に説明する。
本発明者は、上記観点から種々の検討を行い、引張強さが４００ＭＰａ以上の高強度で、且つ、耐磨耗性に優れた生産性の良好なねずみ鋳鉄材（本発明材）を開発した。而して、本発明材は、図１の表の上欄に示すように、Ｃ：２．４〜２．８Ｗｔ％、Ｓｉ：２．３〜３．５Ｗｔ％、Ｍｎ：０．２〜０．８Ｗｔ％、Ｐ：≦０．１Ｗｔ％、Ｓ：≦０．１５Ｗｔ％、Ｃｕ：０．６〜１．４Ｗｔ％、Ｍｏ：≦０．５Ｗｔ％、Ｃｒ：≦０．３Ｗｔ％、残部は実質的にＦｅの化学成分を含有している。本発明材に含有される化学成分としては、例えば、上記各化学成分以外に、Ｎｉ、Ｓｎ、Ｖ、Ｓｂを夫々０．３Ｗｔ％以下なら含有しても良い。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The present inventor has made various studies from the above viewpoint, and has developed a gray cast iron material (the present invention material) having a high tensile strength of 400 MPa or more and excellent wear resistance. . Thus, as shown in the upper column of the table of FIG. 1, the material of the present invention has C: 2.4 to 2.8 Wt%, Si: 2.3 to 3.5 Wt%, Mn: 0.2 to 0 0.8 Wt%, P: ≦ 0.1 Wt%, S: ≦ 0.15 Wt%, Cu: 0.6 to 1.4 Wt%, Mo: ≦ 0.5 Wt%, Cr: ≦ 0.3 Wt%, the balance is substantially In particular, it contains a chemical component of Fe. As a chemical component contained in the material of the present invention, for example, Ni, Sn, V, and Sb may be contained in each of 0.3 Wt% or less in addition to the above chemical components.

又、本発明材では、ＳｉとＣの比（Ｓｉ／Ｃ）を０．９５以上とする。これは図２に示すグラフから明らかなように、引張強さを４００ＭＰａ以上にするには、Ｓｉ／Ｃの比を０．９５以上とすることが必要なためである。   In the material of the present invention, the ratio of Si to C (Si / C) is set to 0.95 or more. As apparent from the graph shown in FIG. 2, this is because the Si / C ratio needs to be 0.95 or more in order to make the tensile strength 400 MPa or more.

更に、本発明材では、Ｓｉ／ＣとＣｕの比（（Ｓｉ／Ｃ）／Ｃｕ）を１．５以下とする。これは図３に示すグラフから明らかなように、引張強さを４００ＭＰａ以上にするには、（（Ｓｉ／Ｃ）／Ｃｕ）の比を１．５以下とすることが必要なためである。本発明材の組織調整として、接種処理は行っても行わなくても良い。なお、参考として、従来材（ＦＣ２５０）の化学成分を図１の表の下欄に示してある。   Furthermore, in this invention material, ratio ((Si / C) / Cu) of Si / C and Cu shall be 1.5 or less. This is because, as is apparent from the graph shown in FIG. 3, it is necessary to set the ratio of ((Si / C) / Cu) to 1.5 or less in order to make the tensile strength 400 MPa or more. Inoculation treatment may or may not be performed as a tissue adjustment of the material of the present invention. For reference, the chemical composition of the conventional material (FC250) is shown in the lower column of the table of FIG.

鋳鉄組織内の片状黒鉛は、従来材（ＦＣ２５０）においては図５に示すように長いが、本発明材は従来材と比較して緻密で、図４に示すように、微細な片状黒鉛が基地組織中に分散している。基地組織は、緻密なパーライト又は、パーライトに若干のフェライトが加わったものである。   The flake graphite in the cast iron structure is long as shown in FIG. 5 in the conventional material (FC250), but the material of the present invention is denser than the conventional material, and the flake graphite is fine as shown in FIG. Are dispersed throughout the base organization. The base organization is dense pearlite or pearlite with some ferrite added.

本発明材の引張強さは、図６に示すように、約４４０ＭＰａである。従来材のＣｒ−Ｍｏ合金鋳鉄（ＦＣ２５０）の引張強さは約２８０ＭＰａであるから、本発明材においては、約６０％の引張強さの向上が見られた。又、本発明材の疲労限は図７のＮ−Ｓ曲線に示すように、１５０ＭＰａ以上であり、従来材のＣｒ−Ｍｏ合金鋳鉄（ＦＣ２５０）の疲労限は約９５ＭＰａであるから、約６０％の疲労限の向上が見られた。更に、本発明材の硬さは、≦ＨＶ２８０で、従来材よりも若干高い程度であった。   The tensile strength of the material of the present invention is about 440 MPa as shown in FIG. Since the tensile strength of Cr-Mo alloy cast iron (FC250) of the conventional material is about 280 MPa, the tensile strength of the present invention material was improved by about 60%. Further, the fatigue limit of the material of the present invention is 150 MPa or more as shown in the NS curve of FIG. 7, and the fatigue limit of the conventional Cr—Mo alloy cast iron (FC250) is about 95 MPa. The fatigue limit was improved. Furthermore, the hardness of the material of the present invention was ≦ HV280, which was slightly higher than that of the conventional material.

従来材のＣｒ−Ｍｏ合金鋳鉄（ＦＣ２５０）と本発明材の耐磨耗試験を往復動磨耗試験機を用いて図８に示すように行った。図中、１は従来材若しくは本発明材の試験片であり、試験片１は８ｍｍのストロークで往復動を行わせるようになっている。２は往復動試験機における円筒状でＳＵＪ２製の荷重付与材であり、荷重付与材２を介し、試験片１に対し所定の荷重Ｗを付与し得るようになっている。   A conventional Cr—Mo alloy cast iron (FC250) and the wear resistance test of the present invention material were performed as shown in FIG. 8 using a reciprocating wear tester. In the figure, 1 is a test piece of a conventional material or a material of the present invention, and the test piece 1 is made to reciprocate with a stroke of 8 mm. 2 is a load applying material made of SUJ2 in a cylindrical shape in a reciprocating test machine, and a predetermined load W can be applied to the test piece 1 through the load applying material 2.

而して、荷重Ｗにより試験片１に付与される面圧を５７５ＭＰａ、試験片１の滑り速度を平均速度で０．３ｍ／ｓと、０．０７ｍ／ｓの２水準、滑り距離を４０００ｍとし、試験開始時のみ潤滑油としてエンジンオイルを給油し、雰囲気温度を室温にして耐磨耗試験を行った。   Thus, the surface pressure applied to the test piece 1 by the load W is 575 MPa, the sliding speed of the test piece 1 is 0.3 m / s as an average speed, two levels of 0.07 m / s, and the sliding distance is 4000 m. The engine oil was supplied as a lubricating oil only at the start of the test, and the wear resistance test was performed at an ambient temperature of room temperature.

耐磨耗試験の結果は図９に示されている。図９において、本発明材の滑り速度０．３ｍ／ｓの場合の磨耗深さは約１．０μｍ、滑り速度０．０７ｍ／ｓの場合の磨耗深さは約１．５μｍである。又、従来材のＣｒ−Ｍｏ合金鋳鉄の滑り速度０．３ｍ／ｓの場合の磨耗深さは約２．５μｍ、滑り速度０．０７ｍ／ｓの場合の磨耗深さは約３．０μｍである。従って、滑り速度０．３ｍ／ｓの場合、本発明材の磨耗深さは、従来材の約２／５に減少し、滑り速度０．０７ｍ／ｓの場合、本発明材の磨耗深さは、従来材の約１／２に減少した。   The results of the abrasion resistance test are shown in FIG. In FIG. 9, the wear depth of the material of the present invention when the sliding speed is 0.3 m / s is about 1.0 μm, and the wear depth when the sliding speed is 0.07 m / s is about 1.5 μm. The wear depth of the conventional Cr—Mo alloy cast iron when the sliding speed is 0.3 m / s is about 2.5 μm, and the wear depth when the sliding speed is 0.07 m / s is about 3.0 μm. . Therefore, when the sliding speed is 0.3 m / s, the wear depth of the material of the present invention is reduced to about 2/5 of the conventional material, and when the sliding speed is 0.07 m / s, the wear depth of the material of the present invention is It was reduced to about 1/2 of the conventional material.

従って、本発明によれば、炭化物の析出が少なく、且つ硬度の大幅な上昇がない耐磨耗性に優れた、引張強さが４００ＭＰａ以上の生産性の良好なねずみ鋳鉄材を得ることができる。   Therefore, according to the present invention, it is possible to obtain a gray cast iron material having excellent productivity with a tensile strength of 400 MPa or more, which is excellent in wear resistance with little carbide precipitation and no significant increase in hardness. .

なお、本発明は上述の図示例にのみ限定されるものではなく、本発明の要旨を逸脱しない範囲内において種々変更を加え得ることは勿論である。   It should be noted that the present invention is not limited only to the illustrated examples described above, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

本発明材と従来材の化学成分（Ｗｔ％）を示す表である。It is a table | surface which shows the chemical component (Wt%) of this invention material and a conventional material. 本発明材のＳｉ／Ｃの比と引張強さＭＰａとの関係を示すグラフである。It is a graph which shows the relationship between ratio of Si / C of this invention material, and tensile strength MPa. 本発明材の（Ｓｉ／Ｃ）／Ｃｕの比と引張強さＭＰａとの関係を示すグラフである。It is a graph which shows the relationship between ratio (Si / C) / Cu of this invention material, and tensile strength MPa. 本発明材の組織写真である。It is a structure photograph of this invention material. 従来材（ＦＣ２５０）の組織写真である。It is a structure photograph of conventional material (FC250). 本発明材及び従来材（ＦＣ２５０）の引張強さＭＰａを示すグラフである。It is a graph which shows the tensile strength MPa of this invention material and a conventional material (FC250). 本発明材及び従来材（ＦＣ２５０）の疲労限を示すＮ−Ｓ曲線である。It is a NS curve which shows the fatigue limit of this invention material and a conventional material (FC250). 本発明材及び従来材（ＦＣ２５０）について行った磨耗試験の状態を示す斜視図である。It is a perspective view which shows the state of the abrasion test done about this invention material and the conventional material (FC250). 本発明材と従来材（ＦＣ２５０）の磨耗深さを示すグラフである。It is a graph which shows the wear depth of this invention material and a conventional material (FC250).

符号の説明Explanation of symbols

１ 試験片
２ 荷重付与材
Ｗ 荷重 1 Test piece 2 Load applying material W load

Claims (1)

重量比で、Ｃ：２．４〜２．８Ｗｔ％、Ｓｉ：２．３〜３．５Ｗｔ％、Ｍｎ：０．２〜０．８Ｗｔ％、Ｐ：≦０．１Ｗｔ％、Ｓ：≦０．１５Ｗｔ％、Ｃｕ：０．６〜１．４Ｗｔ％、Ｍｏ：≦０．５Ｗｔ％、Ｃｒ：≦０．３Ｗｔ％、残部はＦｅである化学成分を含有し、Ｓｉ／Ｃの比を０．９５以上とし、（Ｓｉ／Ｃ）／Ｃｕの比を１．５以下としたことを特徴とするねずみ鋳鉄材。 By weight ratio, C: 2.4-2.8 Wt%, Si: 2.3-3.5 Wt%, Mn: 0.2-0.8 Wt%, P: ≦ 0.1 Wt%, S: ≦ 0.0. 15 Wt%, Cu: 0.6 to 1.4 Wt%, Mo: ≦ 0.5 Wt%, Cr: ≦ 0.3 Wt%, the balance contains a chemical component of Fe , and the ratio of Si / C is 0.95 A gray cast iron material characterized in that the ratio of (Si / C) / Cu is 1.5 or less.
JP2004030683A 2004-02-06 2004-02-06 Gray cast iron Expired - Fee Related JP4395385B2 (en)

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US9200351B2 (en) * 2009-02-12 2015-12-01 Teksid Do Brasil Ltda. High resistance gray iron alloy for combustion engines and general casts
KR101845410B1 (en) * 2012-05-25 2018-04-05 현대자동차주식회사 Heat treatment method of high strength gray cast irons and composition of high strength gray cast irons using thereof
JP6313154B2 (en) * 2014-07-28 2018-04-18 株式会社リケン Cast iron and brake parts
CN105200305B (en) * 2015-09-15 2017-03-08 浙江杭机铸造有限公司 A kind of casting pig and preparation method thereof
CN108588544A (en) * 2018-01-31 2018-09-28 中国航发北京航空材料研究院 A kind of high-performance gray cast iron with comprehensive high-heat performance and mechanical property
CN115141971B (en) * 2022-07-26 2023-11-14 苏州勤美达精密机械有限公司 Vermicular graphite cast iron high-strength hydraulic pump body and production process thereof

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