JP6195727B2 - Cast iron castings and manufacturing method thereof - Google Patents
Cast iron castings and manufacturing method thereof Download PDFInfo
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本発明は鋳鉄鋳物とその製造方法に関する。 The present invention relates to a cast iron casting and a manufacturing method thereof.
高硬度で高耐摩耗性、耐肌荒れ性を必要とする肉厚鋳物、例えば熱間圧延用ロール等では、下記特許文献１、２に開示するように、アダマイト系が用いられている。 In thick castings that require high hardness, high wear resistance, and rough skin resistance, such as hot rolling rolls, adamite systems are used as disclosed in Patent Documents 1 and 2 below.
特許文献１には、アダマイト系のベース組成に、Ｂ、Ａｌ、Ｔｉ、Ｚｒ、Ｃｕ、Ｍｇ、Ｃａ等を添加含有させることで、均一で微細化されたＭ３Ｃ共晶炭化物を晶出させた、外層材からなる熱間圧延用アダマイトロールが開示されている。
また本出願人の以前の出願に係る特許文献２には、アダマイト系のベース組成にＶ等を添加含有させることで、ベイナイトと微細パーライトが混在した基地中に粗大な一次セメンタイトと、微細粒状炭化物、粒状黒鉛が分散した圧延用ロール材と圧延用ロールが開示されている。
In Patent Document 1, uniform and refined M3C eutectic carbide was crystallized by adding B, Al, Ti, Zr, Cu, Mg, Ca and the like to the adamite base composition. An adamite roll for hot rolling made of an outer layer material is disclosed.
In addition, Patent Document 2 relating to the previous application of the present applicant describes that a primary cementite coarse in a base where bainite and fine pearlite are mixed and fine granular carbide by adding V or the like to an adamite base composition. Further, a roll material for rolling in which granular graphite is dispersed and a roll for rolling are disclosed.
しかしながら上記特許文献１の発明においては、Ｂ、Ａｌ、Ｔｉ、Ｚｒ、Ｃｕ、Ｍｇ、Ｃａ等の多種類の成分を添加させなければならない点や、硬い炭化物が基地中に分散する等の問題があった。
また上記特許文献２の発明においては、基地中に粗大な一次セメンタイトが分散するため、鋳物の靭性を悪化させる問題があった。またこのため、特に厚肉鋳物製品やその他、使用環境の厳しい鋳物製品には用いることができないという問題があった。
However, in the invention of the above-mentioned Patent Document 1, there are problems such as the fact that many kinds of components such as B, Al, Ti, Zr, Cu, Mg, and Ca have to be added, and that hard carbides are dispersed in the base. there were.
In the invention of the above-mentioned patent document 2, since coarse primary cementite is dispersed in the base, there is a problem that the toughness of the casting is deteriorated. For this reason, there is a problem that it cannot be used particularly for thick-walled cast products and other cast products with severe use environments.
そこで本発明は上記従来の問題点を解消し、厚肉鋳物としても、高硬度で、靭性、耐摩耗性、耐焼付き性に優れた、よって鋼板圧延などにも適した、鋳鉄鋳物とその製造方法の提供を課題とする。 Therefore, the present invention solves the above-mentioned conventional problems, and cast iron castings and their production that are thick, cast, and have high hardness, excellent toughness, wear resistance, and seizure resistance, and are therefore suitable for rolling steel sheets. It is an object to provide a method.
上記課題を解決する本発明の鋳鉄鋳物は、重量％で、Ｃ：１．８〜２．５％、Ｓｉ：１．０〜２．０％、Ｍｎ：０．２〜１．５％、Ｎｉ：２．０〜４．０％、Ｍｏ：１．５〜２．５％、Ｍｇ：０．０１〜０．１％、Ｃｒ：０〜０．８％、Ａｌ：０〜０．３％、Ｖ、Ｗ、Ｎｂ、Ｃｏを合計で０〜１．０％、を含有し、残りがＦｅからなり、基地の６０％以上をマルテンサイト相で占める組織とすると共に基地中に少なくとも球状黒鉛を分散させた組織としてあることを第１の特徴としている。
また本発明の鋳鉄鋳物は、上記第１の特徴に加えて、重量％で、Ｃ：１．９〜２．４％、Ｓｉ：１．２〜１．８％、Ｍｎ：０．４〜１．３％、Ｎｉ：２．６〜３．８％、Ｍｏ：１．７〜２．４％、Ｍｇ：０．０３〜０．０８％、Ｃｒ：０〜０．７％、Ａｌ：０〜０．２％、Ｖ、Ｗ、Ｎｂ、Ｃｏを合計で０．０１〜０．８％、を含有することを第２の特徴としている。
また本発明の鋳鉄鋳物は、上記第１の特徴に加えて、重量％で、Ｃ：２．０〜２．３％、Ｓｉ：１．４〜１．６％、Ｍｎ：０．６〜１．１％、Ｎｉ：３．０〜３．５％、Ｍｏ：２．０〜２．３％、Ｍｇ：０．０４〜０．０７％、Ｃｒ：０．０１〜０．５％、Ａｌ：０〜０．１％、Ｖ、Ｗ、Ｎｂ、Ｃｏを合計で０．０１〜０．５％、を含有することを第３の特徴としている。
また本発明の鋳鉄鋳物は、上記第１〜第３の何れかの特徴に加えて、基地の７０〜９０％をマルテンサイト相で占める組織にしてあることを第４の特徴としている。
また本発明の鋳鉄鋳物は、上記第１〜第４の何れかの特徴に加えて、基地の８０〜９０％をマルテンサイト相で占め、残りがベイナイト相と残留オーステナイト相の何れか１相若しくは２相からなり、基地中への分散相として球状黒鉛と、鉄と合金成分とＣとによる炭化物とが共晶及び析出にて分散してなる組織にしてあることを第５の特徴としている。
また本発明の鋳鉄鋳物は、上記第１〜第５の何れかの特徴に加えて、硬度をショア硬度（Ｈｓ）で６５〜８５にしてあることを第６の特徴としている。
また本発明の鋳鉄鋳物の製造方法によれば、上記第１〜第６の何れかの特徴に記載の鋳鉄鋳物の製造方法であって、予め成分組成を調整してなる鋳造物を９５０〜１１００℃まで加熱した後、常温まで急冷するようにしたことを第７の特徴としている。
The cast iron casting of the present invention that solves the above problems is, by weight, C: 1.8-2.5%, Si: 1.0-2.0%, Mn: 0.2-1.5%, Ni : 2.0 to 4.0%, Mo: 1.5 to 2.5%, Mg: 0.01 to 0.1%, Cr: 0 to 0.8%, Al: 0 to 0.3%, Containing 0 to 1.0% of V, W, Nb, and Co in total , the remainder is made of Fe , and the structure occupies 60% or more of the matrix in the martensite phase, and at least spherical graphite is dispersed in the matrix The first feature is that the organization is a controlled organization.
Moreover, in addition to the said 1st characteristic, the cast iron casting of this invention is C: 1.9-2.4%, Si: 1.2-1.8%, Mn: 0.4-1 in weight%. .3%, Ni: 2.6-3.8%, Mo: 1.7-2.4%, Mg: 0.03-0.08%, Cr: 0-0.7%, Al: 0 The second feature is that it contains 0.2 %, 0.01% to 0.8% in total of V, W, Nb, and Co.
Moreover, in addition to the said 1st characteristic, the cast iron casting of this invention is C: 2.0-2.3%, Si: 1.4-1.6%, Mn: 0.6-1 in weight%. 0.1%, Ni: 3.0 to 3.5%, Mo: 2.0 to 2.3%, Mg: 0.04 to 0.07%, Cr: 0.01 to 0.5%, Al: The third feature is that it contains 0 to 0.1 %, 0.01 to 0.5% of V, W, Nb, and Co in total .
The cast iron casting of the present invention has a fourth feature that, in addition to any one of the first to third features, a structure occupying 70 to 90% of the base is a martensite phase.
The cast iron casting of the present invention, in addition to any one of the first to fourth features described above, occupies 80 to 90% of the base with the martensite phase, and the remainder is either one of the bainite phase and the residual austenite phase or The fifth feature is that it is composed of two phases and has a structure in which spherical graphite, iron, an alloy component, and a carbide of C are dispersed as a dispersed phase in the matrix by eutectic and precipitation.
The cast iron of the present invention, in addition to the first to fifth any of the features of, and the sixth aspect of that you have to 65-85 hardness degree Shore hardness (Hs).
Moreover, according to the cast iron casting manufacturing method of the present invention, the cast iron casting manufacturing method according to any one of the first to sixth features, wherein the casting obtained by adjusting the component composition in advance is 950 to 1100. The seventh feature is that the sample is rapidly cooled to room temperature after being heated to ° C.
請求項１に記載の鋳鉄鋳物によれば、そこに示された成分組成、相組成により、厚肉鋳物としても、靱性に優れ、また高硬度で、耐摩耗性、耐焼付き性にも優れた、鋼板圧延などにも適した鋳鉄鋳物を現に提供することができる。
また請求項２に記載の鋳鉄鋳物によれば、上記請求項１の構成による作用効果に加えて、成分組成をより好ましい範囲に限定することで、厚肉鋳物としても、より靱性に優れ、またより高硬度で、耐摩耗性、耐焼付き性にも優れた、より鋼板圧延にも適した鋳鉄鋳物を現に安定して提供することができる。
また請求項３に記載の鋳鉄鋳物によれば、上記請求項１の構成による作用効果に加えて、一層、靱性に優れ、また高強度で、耐摩耗性、耐焼付き性にも優れた鋳鉄鋳物を現に安定して提供することができる。
なお、上記請求項１〜３において、Ｖ＋Ｗ＋Ｎｂ＋Ｃｏの合計を１．０重量％以下含有させる場合には、基地中への黒鉛の安定した晶出を維持させながら微細炭化物の分散による硬度向上を確保することができる。
According to the cast iron casting of claim 1, due to the component composition and phase composition shown therein, it is excellent in toughness, high hardness, wear resistance, and seizure resistance, even as a thick casting. In addition, cast iron castings suitable for rolling steel sheets can be provided.
Further, according to the cast iron casting of the second aspect, in addition to the function and effect of the configuration of the first aspect, by limiting the component composition to a more preferable range, it is excellent in toughness even as a thick casting, A cast iron casting having higher hardness, excellent wear resistance and seizure resistance, and more suitable for rolling steel sheets can be provided stably.
Further, according to the cast iron casting of claim 3, in addition to the function and effect of the configuration of claim 1, the cast iron cast is further excellent in toughness, high strength, wear resistance and seizure resistance. Can be provided in a stable manner.
When the total of V + W + Nb + Co is 1.0% by weight or less in claims 1 to 3, the hardness is improved by dispersing fine carbides while maintaining stable crystallization of graphite in the matrix. be able to.
また請求項４に記載の鋳鉄鋳物によれば、上記請求項１〜３の何れかに記載の構成による作用効果に加えて、基地の７０〜９０％をマルテンサイト相で占める組織にしてあることにより、硬度と耐摩耗性を一層向上させた鋳鉄鋳物を提供させることができる。
また請求項５に記載の鋳鉄鋳物によれば、上記請求項１〜４の何れかに記載の構成による作用効果に加えて、基地の８０〜９０％をマルテンサイト相で占め、残りがベイナイト相と残留オーステナイト相の何れか１相若しくは２相からなり、基地中への分散相として球状黒鉛と、鉄と合成成分とＣとによる炭化物とが共晶及び析出にて分散してなる組織にしてあるので、硬度と耐摩耗性に一層優れ、且つ靱性と耐焼付き性に優れた封鉄鋳物を確実に提供することができる。
また請求項６に記載の鋳鉄鋳物によれば、上記請求項１〜５の何れかの構成による作用効果に加えて、硬度をショア硬度（Ｈｓ）で６５〜８５にしてあるので、靱性、硬度、耐摩耗性、耐焼付き性に優れた鋳鉄鋳物を現に安定して提供することができる。
Moreover, according to the cast iron casting of Claim 4, in addition to the effect by the structure in any one of the said Claims 1-3, it is set as the structure | tissue which occupies 70 to 90% of a base in a martensitic phase. Thus, it is possible to provide a cast iron casting having further improved hardness and wear resistance.
Moreover, according to the cast iron casting of Claim 5, in addition to the effect by the structure in any one of the said Claims 1-4, 80 to 90% of a base is occupied with a martensite phase, and the remainder is a bainite phase. And a retained austenite phase, and a structure in which spherical graphite, carbides of iron, synthetic components, and C are dispersed by eutectic and precipitation as a dispersed phase in the matrix. Therefore, it is possible to reliably provide a sealed iron casting that is further excellent in hardness and wear resistance, and has excellent toughness and seizure resistance.
According to the iron casting according to claim 6, in addition to the effects according to any one of the above claims 1 to 5, so are the 65 to 85 hardness degrees in Shore hardness (Hs), toughness, A cast iron casting having excellent hardness, wear resistance, and seizure resistance can be provided in a stable manner.
また請求項７に記載の鋳鉄鋳物の整合方法によれば、上記請求項１〜６の何れかに記載の鋳鉄鋳物の製造方法であって、予め成分方法を調整してなる鋳造物を９５０〜１１００℃まで加熱した後、常温まで冷却するようにしたので、この組成と熱処理によって、現に高硬度で耐摩耗性に優れると共に、球状黒鉛の分散による良好な靱性と良好な耐焼付き性を備えた、厚肉の鋳鉄鋳物を製造することができる。 According to the alignment method of cast iron according to claim 7, a method of manufacturing cast iron according to any one of the claims 1 to 6, the cast product obtained by adjusting the pre-component method 950 to After being heated to 1100 ° C. and then cooled to room temperature, this composition and heat treatment actually provided high hardness and excellent wear resistance, as well as good toughness and good seizure resistance due to the dispersion of spherical graphite. A thick cast iron casting can be manufactured.
本発明の鋳鉄鋳物とその製造法について、先ず実施形態に係る鋳鉄鋳物の成分組成における各成分元素の含有範囲の限定理由を、以下に説明する。 Regarding the cast iron casting of the present invention and the manufacturing method thereof, first, the reasons for limiting the content ranges of the respective component elements in the component composition of the cast iron casting according to the embodiment will be described below.
Ｃの含有量は、１．８〜２．５重量％とする。
Ｃは黒鉛を晶出し、耐焼付き性を向上させる。１．８重量％未満では黒鉛が得られない。一方、２．５重量％を超えると、Ｃｒ、Ｍｏとの一次セメンタイトを多量に形成して靭性が低下する。また冷却が遅くなる厚肉鋳物の場合は、焼入れ性が低下する。
Ｃの含有量は、黒鉛の晶出、焼入れ性を考慮すると、１．９〜２．４重量％がより好ましく、最も好ましくは２．０〜２．３重量％とするのがよい。
The C content is 1.8 to 2.5% by weight.
C crystallizes graphite and improves seizure resistance. If it is less than 1.8% by weight, graphite cannot be obtained. On the other hand, if it exceeds 2.5% by weight, a large amount of primary cementite with Cr and Mo is formed and the toughness is lowered. Further, in the case of a thick casting in which cooling is slow, the hardenability is lowered.
The content of C is more preferably 1.9 to 2.4% by weight, and most preferably 2.0 to 2.3% by weight in consideration of crystallization and hardenability of graphite.
Ｓｉの含有量は、１．０〜２．０重量％とする。
ＳｉはＣの黒鉛化を容易にさせる元素である。このためには１．０重量％が必要である。一方、２．０重量％を超えると鋳物の靭性を低下させる。
Ｓｉの含有量は、Ｃの黒鉛化と靭性の低下防止を考慮すると、１．２〜１．８重量％がより好ましく、更に好ましくは１．４〜１．６重量％とする。
The Si content is 1.0 to 2.0% by weight.
Si is an element that facilitates graphitization of C. For this purpose, 1.0% by weight is required. On the other hand, if it exceeds 2.0% by weight, the toughness of the casting is lowered.
In consideration of graphitization of C and prevention of deterioration of toughness, the Si content is more preferably 1.2 to 1.8% by weight, still more preferably 1.4 to 1.6% by weight.
Ｍｎの含有量は、０．２〜１．５重量％とする。
Ｍｎは溶湯の脱酸脱硫のために０．２重量％以上必要である。また１．５重量％を超えると靭性が低下する。
Ｍｎの含有量は、溶湯の脱酸脱硫と鋳物の靭性を考慮すると、０．４〜１．３重量％がより好ましく、更に好ましくは０．６〜１．１重量％とする。
The Mn content is 0.2 to 1.5% by weight.
Mn is required to be 0.2% by weight or more for deoxidation and desulfurization of the molten metal. On the other hand, if it exceeds 1.5% by weight, the toughness decreases.
The content of Mn is more preferably 0.4 to 1.3% by weight, still more preferably 0.6 to 1.1% by weight in consideration of deoxidation desulfurization of the molten metal and toughness of the casting.
Ｎｉの含有量は、２．０〜４．０重量％とする。
Ｎｉは基地中に固溶して焼入れ性を向上させ、黒鉛化を促進する。２．０重量％未満では焼入れ性の向上の効果が得られない。４．０重量％を超えると焼入れ後の残留オーステナイト量が増え、硬さが下がる。
Ｎｉの含有量は、焼入れ性、Ｃの黒鉛化を考慮すると、２．６〜３．８重量％が好ましく、最も好ましくは３．０〜３．５重量％とする。
The Ni content is set to 2.0 to 4.0% by weight.
Ni dissolves in the base to improve hardenability and promote graphitization. If it is less than 2.0% by weight, the effect of improving hardenability cannot be obtained. If it exceeds 4.0% by weight, the amount of retained austenite after quenching increases and the hardness decreases.
In consideration of hardenability and graphitization of C, the Ni content is preferably 2.6 to 3.8% by weight, and most preferably 3.0 to 3.5% by weight.
Ｍｏの含有量は、１．５〜２．５重量％とする。
Ｍｏは基地中に固溶して焼入れ性を向上させ、焼戻し軟化抵抗を増す。１．５重量％未満では前述の効果が得られない。また２．５重量％を超えると基地中への固溶は飽和し、共晶炭化物が靭性を劣化させる。
Ｍｏの含有量は、焼入れ性、焼戻し軟化抵抗と共晶炭化物による靭性低下を考慮して、より好ましくは１．７〜２．４重量％とし、更に好ましくは２．０〜２．３重量％とするのがよい。
The Mo content is 1.5 to 2.5% by weight.
Mo is dissolved in the base to improve hardenability and increase temper softening resistance. If it is less than 1.5% by weight, the above-mentioned effects cannot be obtained. If it exceeds 2.5% by weight, the solid solution in the matrix is saturated, and the eutectic carbide deteriorates toughness.
The Mo content is more preferably 1.7 to 2.4% by weight, still more preferably 2.0 to 2.3% by weight in consideration of hardenability, temper softening resistance and toughness reduction due to eutectic carbide. It is good to do.
Ｍｇの含有量は、０．０１〜０．１重量％とする。
Ｍｇは晶出する黒鉛を球状化する。０．０１重量％未満では黒鉛が球状化しない。０．１重量％を超えるとＭｇ酸化物が多く残り、欠陥となる。
Ｍｇの含有量は、黒鉛の球状化と鋳物欠陥を考慮すると、０．０３〜０．０８重量％がより好ましく、０．０４〜０．０７重量％が更に好ましい。
The Mg content is 0.01 to 0.1% by weight.
Mg spheroidizes the crystallized graphite. If it is less than 0.01% by weight, the graphite does not spheroidize. If it exceeds 0.1% by weight, a large amount of Mg oxide remains and becomes a defect.
The Mg content is more preferably 0.03 to 0.08% by weight and even more preferably 0.04 to 0.07% by weight in view of spheroidization of graphite and casting defects.
Ｃｒの含有量は、０〜０．８重量％とする。
Ｃｒは共晶炭化物を形成し、硬さを高める効果がある。一方、黒鉛化は阻害する。一部は基地中に固溶して焼入れ性を向上させる。また０．８重量％を超えると黒鉛化しなくなる。
Ｃｒの含有量は、共晶炭化物の形成、黒鉛化、焼入れ性を考慮して、０〜０．７重量％がより好ましく、０．０１〜０．５重量％が更に好ましい。
The Cr content is 0 to 0.8% by weight.
Cr forms an eutectic carbide and has the effect of increasing the hardness. On the other hand, graphitization is inhibited. Some are dissolved in the base to improve hardenability. If it exceeds 0.8% by weight, it will not graphitize.
The content of Cr is more preferably 0 to 0.7% by weight and further preferably 0.01 to 0.5% by weight in consideration of the formation of eutectic carbide, graphitization, and hardenability.
Ｖ、Ｗ、Ｎｂ、Ｃｏは、合計で１．０重量％以下含有させることができる。Ｖ、Ｗ、Ｎｂ、Ｃｏは炭化物生成元素であり、硬度向上、耐摩耗性向上に役立つ。ただし１．０重量％を超えると黒鉛化を阻害し、靭性、耐焼付き性を阻害する。
Ｖ、Ｗ、Ｎｂ、Ｃｏの合計は、黒鉛化による靭性、耐焼付き性の向上と炭化物分散による硬度、耐摩耗性の向上を考慮して、０．０１〜０．８重量％がより好ましく、０．０１〜０．５重量％が更に好ましい。
勿論、Ｖ、Ｗ、Ｎｂ、Ｃｏは含有させなくてもよい。
V, W, Nb, and Co can be contained in a total amount of 1.0% by weight or less. V, W, Nb, and Co are carbide generating elements, and are useful for improving hardness and wear resistance. However, if it exceeds 1.0% by weight, graphitization is inhibited, and toughness and seizure resistance are inhibited.
The total of V, W, Nb, and Co is more preferably 0.01 to 0.8% by weight in consideration of improvement in toughness due to graphitization, seizure resistance and hardness due to carbide dispersion, and improvement in wear resistance. More preferably, it is 0.01 to 0.5% by weight.
Of course, V, W, Nb, and Co may not be contained.
Ａｌは脱酸剤として用いることができる。０．３重量％を超えると鋳造性が悪くなるため、０．３重量％以下とする。好ましくは０．２重量％以下とし、更に好ましくは０．１重量％以下とするのがよい。 Al can be used as a deoxidizer. If it exceeds 0.3% by weight, castability deteriorates, so the content is made 0.3% by weight or less. The content is preferably 0.2% by weight or less, and more preferably 0.1% by weight or less.
次に上述の成分組成の鋳鉄材料を用いた鋳造鋳物の製造方法について説明する。
製造方法は、所定の成分組成としたものを溶融炉で溶かし、これを一旦、鋳込んで鋳鉄鋳物を得る。次に、この鋳放し状態の鋳鉄鋳物を９５０〜１１００℃の温度に加熱し、２〜１０時間保持して後、常温まで冷却する。
この場合、加熱温度が９５０℃未満では基地中のＣ濃度が低下し、硬さが低下する。更に基地中のＣｒ、Ｍｏ濃度も低下し、焼入れ性が悪くなる。一方、１１００℃を超えるとＣの黒鉛化が必要以上に進行し、靭性を劣化させる。
また保持時間が２時間未満であると、共晶炭化物の黒鉛化がなされない。一方、１０時間を超えると黒鉛が粗大になると共に、硬度も低下する。
加熱温度は、基地中のＣ濃度の他、Ｃｒ、Ｍｏ濃度、焼入れ性、黒鉛化を考慮して、９７０〜１０８０℃が好ましく、更に９９０〜１０６０℃がより好ましい。
また保持時間は、共晶炭化物の黒鉛化促進と黒鉛の粗大化の防止を考慮して、３〜８時間がより好ましく、４〜６時間が更に好ましい。
前記常温までの冷却は、冷却速度が０．２℃／秒以上となるようにして行っている。０．２℃／秒より遅いと、ベイナイト変態が生じ、マルテンサイト相の割合が６０％未満となる。
Next, a method for producing a cast casting using the cast iron material having the above component composition will be described.
A manufacturing method melt | dissolves what was made into the predetermined component composition with a melting furnace, and once casts this, a cast iron casting is obtained. Next, the cast iron cast in an as-cast state is heated to a temperature of 950 to 1100 ° C., held for 2 to 10 hours, and then cooled to room temperature.
In this case, when the heating temperature is lower than 950 ° C., the C concentration in the base is lowered and the hardness is lowered. Furthermore, the Cr and Mo concentrations in the base also decrease, and the hardenability deteriorates. On the other hand, when the temperature exceeds 1100 ° C., graphitization of C proceeds more than necessary and deteriorates toughness.
Further, if the holding time is less than 2 hours, the eutectic carbide is not graphitized. On the other hand, if it exceeds 10 hours, the graphite becomes coarse and the hardness also decreases.
The heating temperature is preferably 970 to 1080 ° C., more preferably 990 to 1060 ° C., taking into account the Cr concentration, Mo concentration, hardenability, and graphitization in addition to the C concentration in the base.
The holding time is more preferably 3 to 8 hours, and further preferably 4 to 6 hours in consideration of acceleration of graphitization of the eutectic carbide and prevention of graphite coarsening.
The cooling to room temperature is performed so that the cooling rate is 0.2 ° C./second or more. When it is slower than 0.2 ° C./second, bainite transformation occurs and the ratio of martensite phase is less than 60%.
本発明の係る成分組成の鋳物は上記の熱処理により、また複数回の焼戻し処理等を行うことなく、基地の６０〜９５％がマルテンサイト相から、残りがベイナイト相や残留オーステナイト相となる。また基地中への分散相としては、球状黒鉛が基地中に分散し、且つ粗大な一次炭化物は存在せず、鉄と合金成分とＣとによる複合炭化物が共晶及び析出にて微細に分散した組織を得ることができる。
本発明の鋳物においては、前記基地に占めるマルテンサイト相の比率を６０〜９５％、残りがベイナイト相と残留オーステナイト相となる組織にするが、硬度、耐摩耗性を考慮して、基地組織としてマルテンサイト層が７０〜９０％を占めることがより好ましく、８０〜９０％を占めることが最も好ましいと言える。
The casting of the component composition according to the present invention undergoes the above heat treatment, and without performing multiple tempering treatments, 60 to 95% of the base is from the martensite phase, and the rest is the bainite phase or the residual austenite phase. In addition, as a dispersed phase in the matrix, spherical graphite is dispersed in the matrix, and there is no coarse primary carbide, and a composite carbide of iron, an alloy component, and C is finely dispersed by eutectic and precipitation. You can get an organization.
In the casting of the present invention, the ratio of the martensite phase occupying the base is 60 to 95%, and the rest is a structure in which the bainite phase and the residual austenite phase are formed. More preferably, the martensite layer accounts for 70 to 90%, and most preferably 80 to 90%.
このような熱処理により、上記のような鋳物組織を得ることができ、高靭性で、耐焼付き性に優れ、且つショア硬度（Ｈｓ）で６５〜８５の高硬度で、耐摩耗性に優れ、例えば厚みが１５０ｍｍ以上の肉厚鋳物にも適した鋳鉄鋳物を安定して得ることができる。また鋼板圧延にも適した鋳鉄鋳物を安定して提供することができる。 By such heat treatment, it is possible to obtain a cast structure as described above, high toughness, excellent seizure resistance, high hardness of 65 to 85 in Shore hardness (Hs), and excellent wear resistance. A cast iron casting suitable for a thick casting having a thickness of 150 mm or more can be stably obtained. Moreover, the cast iron casting suitable also for steel plate rolling can be provided stably.
実施例１〜１２、比較例１〜６の各材料を、表１〜表３に示すような成分組成となるように鋳造した。その後、表４に示す各焼入温度（９３０〜１１２０℃）で３〜４時間保持した後、常温まで０．３℃／秒の冷却速度で冷却した。 The materials of Examples 1 to 12 and Comparative Examples 1 to 6 were cast so as to have component compositions as shown in Tables 1 to 3. Then, after hold | maintaining at each quenching temperature (930-1120 degreeC) shown in Table 4 for 3 to 4 hours, it cooled with the cooling rate of 0.3 degree-C / sec to normal temperature.
得られた実施例１〜１２、比較例１〜６の各鋳物のショア硬度（Ｈｓ）を測定し、また基地に分散した黒鉛形状を観察した。
結果を表４に示す。
表４において、黒鉛形状が球状黒鉛のものには「球」と、片状黒鉛や粗大黒鉛のものには「片」と、黒鉛が確認できないものには「−」と、それぞれ表記した。
耐焼付き性については黒鉛が晶出しているものを良とした。
靭性については球状黒鉛が分散しているものを良とした。
硬度、耐摩耗性はショア硬度（Ｈｓ）が６５以上のものを良とした。
そして表４での判定は、前記耐焼付き性（黒鉛晶出の有無）、靭性（球状黒鉛の分散）、硬度、耐摩耗性の全てが良であるものを合格として「○」とした。それ以外は失格として「×」をつけた。
The Shore hardness (Hs) of each casting obtained in Examples 1 to 12 and Comparative Examples 1 to 6 was measured, and the graphite shape dispersed in the base was observed.
The results are shown in Table 4.
In Table 4, “spherical” is used when the graphite shape is spherical graphite, “piece” when the flake graphite or coarse graphite is not, and “−” when graphite is not confirmed.
With respect to seizure resistance, those with crystallized graphite were considered good.
Regarding toughness, those in which spherical graphite was dispersed were considered good.
Hardness and wear resistance were those with a Shore hardness (Hs) of 65 or more.
The determination in Table 4 was evaluated as “O” when the seizure resistance (presence / absence of crystallization of graphite), toughness (dispersion of spherical graphite), hardness, and wear resistance were all acceptable. Otherwise, “X” was given as disqualification.
前記実施例１〜１２のうち、実施例２、３、５、８、１０、１２は成分組成がより好ましい範囲にあり、実施例７、９は成分組成が更に好ましい範囲にある。
前記比較例１〜６は何れも成分組成が本発明の成分組成には入っていない。
なお表４に示す評価においては、必ずしも前記実施例１、４、６、１１と、より好ましい実施例２、３、５、８、１０、１２と、更に好ましい実施例７、９との差は示されていないが、好ましい実施例、より好ましい実施例になるにつれて、全体としての評価が増す。
Among Examples 1 to 12, Examples 2, 3, 5, 8, 10, and 12 are in a range in which the component composition is more preferable, and Examples 7 and 9 are in a range in which the component composition is further preferable.
In any of Comparative Examples 1 to 6, the component composition is not included in the component composition of the present invention.
In the evaluation shown in Table 4, the difference between Examples 1, 4, 6, 11 and more preferable Examples 2, 3, 5, 8, 10, 12 and more preferable Examples 7 and 9 is not necessarily Although not shown, the overall rating increases as the preferred and more preferred embodiments.
Claims (7)
Ｃ ：１．８〜２．５％、
Ｓｉ：１．０〜２．０％、
Ｍｎ：０．２〜１．５％、
Ｎｉ：２．０〜４．０％、
Ｍｏ：１．５〜２．５％、
Ｍｇ：０．０１〜０．１％、
Ｃｒ：０〜０．８％、
Ａｌ：０〜０．３％、
Ｖ、Ｗ、Ｎｂ、Ｃｏを合計で０〜１．０％、
を含有し、残りがＦｅからなり、
基地の６０％以上をマルテンサイト相で占める組織とすると共に基地中に少なくとも球状黒鉛を分散させた組織としてあることを特徴とする鋳鉄鋳物。 % By weight
C: 1.8-2.5%,
Si: 1.0-2.0%,
Mn: 0.2 to 1.5%
Ni: 2.0 to 4.0%,
Mo: 1.5-2.5%,
Mg: 0.01 to 0.1%,
Cr: 0 to 0.8%,
Al: 0 to 0.3%,
0 to 1.0% in total of V, W, Nb and Co,
And the remainder consists of Fe,
A cast iron casting characterized by having a structure in which 60% or more of the base is occupied by a martensite phase and at least spheroidal graphite is dispersed in the base.
Ｃ ：１．９〜２．４％、
Ｓｉ：１．２〜１．８％、
Ｍｎ：０．４〜１．３％、
Ｎｉ：２．６〜３．８％、
Ｍｏ：１．７〜２．４％、
Ｍｇ：０．０３〜０．０８％、
Ｃｒ：０〜０．７％、
Ａｌ：０〜０．２％、
Ｖ、Ｗ、Ｎｂ、Ｃｏを合計で０．０１〜０．８％、
を含有することを特徴とする請求項１に記載の鋳鉄鋳物。 % By weight
C: 1.9 to 2.4%,
Si: 1.2 to 1.8%,
Mn: 0.4 to 1.3%
Ni: 2.6 to 3.8%,
Mo: 1.7-2.4%,
Mg: 0.03-0.08%,
Cr: 0 to 0.7%,
Al: 0 to 0.2 %,
V, W, Nb, Co in total 0.01-0.8%,
The cast iron casting according to claim 1, comprising:
Ｃ ：２．０〜２．３％、
Ｓｉ：１．４〜１．６％、
Ｍｎ：０．６〜１．１％、
Ｎｉ：３．０〜３．５％、
Ｍｏ：２．０〜２．３％、
Ｍｇ：０．０４〜０．０７％、
Ｃｒ：０．０１〜０．５％、
Ａｌ：０〜０．１％、
Ｖ、Ｗ、Ｎｂ、Ｃｏを合計で０．０１〜０．５％、
を含有することを特徴とする請求項１に記載の鋳鉄鋳物。 % By weight
C: 2.0 to 2.3%
Si: 1.4 to 1.6%,
Mn: 0.6 to 1.1%
Ni: 3.0-3.5%
Mo: 2.0 to 2.3%
Mg: 0.04 to 0.07%,
Cr: 0.01 to 0.5%
Al: 0 to 0.1 %,
V, W, Nb, Co in total 0.01 to 0.5%,
The cast iron casting according to claim 1, comprising:
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