JP2018044217A - Manufacturing method of hypoeutectic spheroidal graphite cast iron cast - Google Patents
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- 229910001141 Ductile iron Inorganic materials 0.000 title claims abstract description 61
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 40
- 238000001816 cooling Methods 0.000 claims abstract description 38
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 34
- 229910001566 austenite Inorganic materials 0.000 claims abstract description 27
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 27
- 239000000203 mixture Substances 0.000 claims abstract description 26
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000011159 matrix material Substances 0.000 claims abstract description 12
- 238000005266 casting Methods 0.000 claims description 69
- 238000010438 heat treatment Methods 0.000 claims description 61
- 238000011282 treatment Methods 0.000 claims description 27
- 239000002184 metal Substances 0.000 claims description 6
- 229910052751 metal Inorganic materials 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 238000000151 deposition Methods 0.000 abstract 1
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- 239000010439 graphite Substances 0.000 description 53
- 230000000694 effects Effects 0.000 description 23
- 238000005087 graphitization Methods 0.000 description 17
- 229910052802 copper Inorganic materials 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 12
- 229910052759 nickel Inorganic materials 0.000 description 11
- 238000000034 method Methods 0.000 description 10
- 235000019589 hardness Nutrition 0.000 description 9
- 230000001737 promoting effect Effects 0.000 description 8
- 229910001567 cementite Inorganic materials 0.000 description 7
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 7
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- 229910000734 martensite Inorganic materials 0.000 description 3
- 238000005728 strengthening Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 229910001296 Malleable iron Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 238000005469 granulation Methods 0.000 description 2
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 229910052726 zirconium Inorganic materials 0.000 description 2
- 229910017112 Fe—C Inorganic materials 0.000 description 1
- 241000446313 Lamella Species 0.000 description 1
- 229910001035 Soft ferrite Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
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- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
Description
本発明は亜共晶球状黒鉛鋳鉄鋳物の製造方法に関する。 The present invention relates to a method for producing hypoeutectic spheroidal graphite cast iron castings.
高強度、高靱性、高剛性などの物性が要求される摺動部分を有する部材（摺動部材）では、剛性面では鋼材が適するが、黒鉛が存在しないため摺動性に劣る。また鋳鉄では摺動性は適するが、剛性が劣るという問題がある。また球状黒鉛鋳鉄では摺動性には優れるが、剛性面では十分ではないために設計上の制約が生じてしまう。
また剛性と摺動性を満足する素材としては可鍛鋳鉄がある。しかし可鍛鋳鉄の場合は、鋳造時には白鋳鉄で、それを黒鉛化熱処理するという製造方法となり、鋳造時に鋳巣が出易いため大きな押し湯が必要となって歩留まりが悪くなる問題、また黒鉛化熱処理に長時間を要する問題があり、コストも高くなる。また白鋳鉄を黒鉛化処理して得られる黒鉛は塊状の黒鉛になっているため、球状黒鉛とは言えず球状化率が悪く、伸びが悪い。
これらの問題を解決するために本出願人は、特願２０１５−５４６３１号において、亜共晶球状黒鉛鋳鉄を提供した。該出願に係る亜共晶球状黒鉛鋳鉄では、鋳放しのままで、セメンタイトが晶出することなく、よって白鋳鉄化することなく、しかも晶出する黒鉛の面積率が小さく、黒鉛球状化率が高い、高ヤング率を有する亜共晶球状黒鉛鋳鉄鋳物を提供できるメリットがある。
In a member having a sliding portion (sliding member) that requires physical properties such as high strength, high toughness, and high rigidity (sliding member), a steel material is suitable in terms of rigidity, but since there is no graphite, the sliding property is inferior. Moreover, although slidability is suitable in cast iron, there exists a problem that rigidity is inferior. In addition, spheroidal graphite cast iron is excellent in slidability, but it is not sufficient in terms of rigidity, resulting in design limitations.
Another material that satisfies both rigidity and slidability is malleable cast iron. However, in the case of malleable cast iron, white cast iron is used for casting, and it is a method of heat treatment for graphitization. There is a problem that the heat treatment takes a long time, and the cost is increased. In addition, graphite obtained by graphitizing white cast iron is in the form of lump graphite, so it cannot be said to be spheroidal graphite and has a poor spheroidization rate and poor elongation.
In order to solve these problems, the present applicant provided hypoeutectic spheroidal graphite cast iron in Japanese Patent Application No. 2015-54631. In the hypoeutectic spheroidal graphite cast iron according to the application, as-cast, cementite does not crystallize, and thus does not become white cast iron, and the area ratio of the crystallized graphite is small, and the graphite spheroidization ratio is low. There is an advantage that a hypoeutectic spheroidal graphite cast iron casting having a high and high Young's modulus can be provided.
上記特許文献１の発明は、強靭球状黒鉛鋳鉄並びにその熱処理方法に関し、熱処理として、共析変態温度区域内の温度まで加熱して、フェライト、オーステナイト及び黒鉛の共存する組織とし、ついでその温度から常温まで空冷するようにした熱処理方法が開示されている。しかしながら。特許文献１の鋳鉄の成分組成では、Ｃ、Ｓｉが共に多く、過共晶組成に近い組成を前提としている。
上記特許文献２の発明は、球状黒鉛鋳鉄とその製造方法に関し、熱処理として、α＋γの共存域まで加熱した後、強制冷却するようにした熱処理方法が開示されている。しかしながら、この特許文献２の鋳鉄の場合も特許文献１と同様に、過共晶組成に近い組成を前提としており、しかも高価な合金成分の添加を前提としている。
上記特許文献３の発明は、亜共晶球状黒鉛鋳鉄に関し、鋳放しのままでも遊離セメンタイトが晶出することなく、晶出する黒鉛の面積率が小さく、黒鉛球状化率が高い、高ヤング率の機械的性質を得ることができる。しかし鋳放しのままの場合には、肉厚によって組織の相異が大きくなり易く、硬度差等の機械的性質のバラツキが大きくなる問題がある。
The invention of Patent Document 1 relates to tough spheroidal graphite cast iron and a heat treatment method thereof, and as a heat treatment, the structure is formed by heating to a temperature in the eutectoid transformation temperature region to coexist with ferrite, austenite, and graphite. A heat treatment method in which air cooling is performed is disclosed. However. The component composition of cast iron disclosed in Patent Document 1 is premised on a composition that is rich in both C and Si and is close to a hypereutectic composition.
The invention of Patent Document 2 relates to spheroidal graphite cast iron and a method for producing the same, and a heat treatment method is disclosed in which heat treatment is performed after heating to the coexistence region of α + γ and then forcibly cooling. However, in the case of the cast iron of Patent Document 2, similarly to Patent Document 1, it is premised on a composition close to the hypereutectic composition, and is premised on the addition of expensive alloy components.
The invention of Patent Document 3 relates to hypoeutectic spheroidal graphite cast iron, and the free cementite does not crystallize even in the as-cast state, the area ratio of the crystallized graphite is small, the graphite spheroidization ratio is high, and the high Young's modulus The mechanical properties of can be obtained. However, in the case of as-cast, there is a problem that the difference in structure tends to increase depending on the thickness, and the variation in mechanical properties such as hardness difference becomes large.
そこで本発明は上記従来技術の欠点を解消し、強度、靱性、摺動性に優れると共に、肉厚差による機械的性質のバラツキが少ない亜共晶球状黒鉛鋳鉄鋳物の製造方法の提供を課題とする。 Accordingly, the present invention has an object to provide a method for producing a hypoeutectic spheroidal graphite cast iron casting that eliminates the above-mentioned disadvantages of the prior art and is excellent in strength, toughness, and slidability, and has little variation in mechanical properties due to a difference in thickness. To do.
上記課題を解決する本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、質量パーセントで、Ｃ：１．５〜２．７％、Ｓｉ：１．０〜４．５％、Ａｌ：０．０１〜０．２％、Ｍｇ：０．０１５〜０．０６０％を含有し、残部がＦｅからなる成分組成を有し、
溶湯から一旦鋳造してなる出発鋳物を、先ず常温から２００℃／時間以下の昇温処理速度で、７８０〜８７０℃の熱処理温度まで昇温し、該熱処理温度で０．５〜１５時間保持して、基地をフェライトとオーステナイトからなる組織とし、次に前記熱処理温度から０．５〜６０℃／分の冷却処理速度により常温まで冷却処理して、オーステナイトからパーライトとフェライトを析出させ、基地をフェライトとパーライトからなる組織とすることを第１の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第１の特徴に加えて、熱処理温度を７８０〜８５０℃とし、熱処理温度からの冷却処理速度を０．５〜３０℃／分としたことを第２の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第２の特徴に加えて、熱処理温度を８００〜８５０℃とし、熱処理温度からの冷却処理速度を１〜３０℃／分としたことを第３の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第１〜第３の何れかの特徴に加えて、質量パーセントで、Ｃ：１．５〜２．７％、Ｓｉ：１．０〜４．５％、Ａｌ：０．０１〜０．２％、Ｃｕ＋Ｎｉ：０．０１〜２．０％、Ｍｇ：０．０１５〜０．０６０％を含有し、残部がＦｅからなる成分組成を有することを第４の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第４の特徴に加えて、質量パーセントで、Ｃ：１．５〜２．７％、Ｓｉ：１．０〜４．５％、Ａｌ：０．０１〜０．２％、Ｎｉ：０．０１〜２．０％、Ｃｕ＋Ｎｉ：０．０１〜２．０％、Ｍｇ：０．０１５〜０．０６０％を含有し、残部がＦｅからなる成分組成を有することを第５の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第５の特徴に加えて、質量パーセントで、Ｃ：１．５〜２．７％、Ｓｉ：１．０〜４．５％、Ａｌ：０．０１〜０．２％、Ｎｉ：０．０５〜１．６％、Ｃｕ：０．０５〜１．６％、Ｃｕ＋Ｎｉ：０．１〜２．０％、Ｍｇ：０．０１５〜０．０６０％を含有し、残部がＦｅからなる成分組成を有することを第６の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第６の特徴に加えて、質量パーセントで、Ｃ：１．５〜２．７％、Ｓｉ：１．０〜４．５％、Ａｌ：０．０１〜０．２％、Ｎｉ：０．１〜１．２％、Ｃｕ：０．１〜１．２％、Ｃｕ＋Ｎｉ：０．２〜１．６％、Ｍｇ：０．０１５〜０．０６０％を含有し、残部がＦｅからなる成分組成を有することを第７の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第１〜第７の何れかの特徴に加えて、質量パーセントで、Ｃ：１．５〜２．５％、Ｓｉ：１．６〜４．０％とすることを第８の特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第８の特徴に加えて、質量パーセントで、Ｃ：１．５〜２．４％、Ｓｉ：１．８〜３．５％とすることを第９特徴としている。
また本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法は、上記第１〜第９の何れかの特徴に加えて、質量パーセントで、Ｍｎ：１．０％未満とすることを第１０の特徴としている。
The manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of the present invention that solves the above problems is, in mass percent, C: 1.5 to 2.7%, Si: 1.0 to 4.5%, Al: 0.00. Containing 0.1 to 0.2%, Mg: 0.015 to 0.060%, with the balance being composed of Fe,
A starting casting once cast from the molten metal is first heated from room temperature to a heat treatment temperature of 780 to 870 ° C. at a heating rate of 200 ° C./hour or less, and held at the heat treatment temperature for 0.5 to 15 hours. Then, the matrix is made of a structure composed of ferrite and austenite, and then cooled from the heat treatment temperature to room temperature at a cooling rate of 0.5 to 60 ° C./min to precipitate pearlite and ferrite from the austenite. The first feature is that the structure is made of pearlite.
In addition to the first feature, the method for producing a hypoeutectic spheroidal graphite cast iron casting of the present invention has a heat treatment temperature of 780 to 850 ° C., and a cooling treatment rate from the heat treatment temperature of 0.5 to 30 ° C./min. This is the second feature.
In addition to the second feature, the method for producing a hypoeutectic spheroidal graphite cast iron casting of the present invention has a heat treatment temperature of 800 to 850 ° C. and a cooling treatment speed from the heat treatment temperature of 1 to 30 ° C./min. This is the third feature.
Moreover, the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting according to the present invention includes, in addition to any one of the first to third features, C: 1.5 to 2.7%, Si: 1. Component composition comprising 0 to 4.5%, Al: 0.01 to 0.2%, Cu + Ni: 0.01 to 2.0%, Mg: 0.015 to 0.060%, the balance being Fe It has the 4th characteristic to have.
In addition to the fourth feature, the method for producing a hypoeutectic spheroidal graphite cast iron casting of the present invention includes, in mass percent, C: 1.5 to 2.7%, Si: 1.0 to 4.5% Al: 0.01-0.2%, Ni: 0.01-2.0%, Cu + Ni: 0.01-2.0%, Mg: 0.015-0.060%, the balance being The fifth feature is that it has a component composition of Fe.
In addition to the fifth feature, the method for producing a hypoeutectic spheroidal graphite cast iron casting according to the present invention includes, in mass percent, C: 1.5 to 2.7%, Si: 1.0 to 4.5% Al: 0.01-0.2%, Ni: 0.05-1.6%, Cu: 0.05-1.6%, Cu + Ni: 0.1-2.0%, Mg: 0.015 The sixth feature is that it contains ˜0.060% and the remainder has a component composition made of Fe.
Moreover, in addition to the said 6th characteristic, the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of this invention is C: 1.5-2.7%, Si: 1.0-4.5% in a mass percentage. Al: 0.01-0.2%, Ni: 0.1-1.2%, Cu: 0.1-1.2%, Cu + Ni: 0.2-1.6%, Mg: 0.015 The seventh feature is that it contains ˜0.060% and the remainder has a component composition made of Fe.
Moreover, the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of the present invention includes, in addition to any one of the above first to seventh features, C: 1.5 to 2.5%, Si: 1. The eighth feature is that the content is 6 to 4.0%.
In addition to the eighth feature, the method for producing a hypoeutectic spheroidal graphite cast iron casting according to the present invention includes, in mass percent, C: 1.5 to 2.4%, Si: 1.8 to 3.5% This is the ninth feature.
The method for producing a hypoeutectic spheroidal graphite cast iron casting according to the present invention, in addition to any one of the first to ninth features described above, has a tenth feature in that Mn is less than 1.0% by mass percent. It is said.
請求項１に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、そこに示された所定の成分組成の鋳物に対して、２００℃／時間以下の昇温処理速度で７８０〜８７０℃の熱処理温度まで昇温し、その熱処理温度で０．５〜１５時間保持した後、０．５〜６０℃／分の冷却処理速度で冷却処理することにより、現に、晶出する黒鉛の面積率が小さく、黒鉛球状化率が高く、高ヤング率（例えば通常の球状黒鉛鋳鉄鋳物のヤング率が１４０〜１７０ＧＰａであるのに対して１７５ＧＰａ以上、更には１８０ＧＰａ以上）を有する、強度、靱性、摺動性に優れた亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。しかも製品の肉厚差による機械的性質のバラツキが十分に抑制された、安定した亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
また請求項２に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項１に記載の構成による作用効果に加えて、熱処理温度を７８０〜８５０℃に限定し、熱処理温度からの冷却処理速度を０．５〜３０℃／分と限定することで、一層容易、確実に、強度、靱性、摺動性に優れ、且つ肉厚による機械的性質のバラツキが少ない亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
また請求項３に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項２に記載の構成による作用効果に加えて、熱処理温度を更に８００〜８５０℃と限定し、熱処理温度からの冷却処理速度を更に１〜３０℃／分と限定することにより、更に一層容易、確実に、強度、靱性、摺動性に優れ、且つ肉厚による機械的性質のバラツキが少ない亜共晶球状黒鉛鋳鉄鋳物を製造することができる。
According to the method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 1, 780 to 870 ° C. at a heating rate of 200 ° C./hour or less with respect to a casting having a predetermined component composition shown therein. The area ratio of graphite that is actually crystallized by cooling at a heat treatment temperature of 0.5 to 60 ° C./min after the temperature is raised to the heat treatment temperature of Strength, toughness, slipperiness, high graphite spheroidization ratio, and high Young's modulus (for example, 175 GPa or more compared to 140 to 170 GPa for ordinary spheroidal graphite cast iron castings). It becomes possible to manufacture hypoeutectic spheroidal graphite cast iron castings with excellent mobility. In addition, it is possible to produce a stable hypoeutectic spheroidal graphite cast iron casting in which variations in mechanical properties due to product thickness differences are sufficiently suppressed.
Further, according to the method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 2, in addition to the function and effect of the structure according to claim 1, the heat treatment temperature is limited to 780 to 850 ° C. By limiting the cooling treatment speed of the material to 0.5 to 30 ° C./min, hypoeutectic spheres are more easily and surely excellent in strength, toughness, and slidability, and have little variation in mechanical properties due to thickness. It becomes possible to produce a graphite cast iron casting.
In addition, according to the method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 3, in addition to the function and effect of the configuration according to claim 2, the heat treatment temperature is further limited to 800 to 850 ° C. By further limiting the cooling processing rate from 1 to 30 ° C./min, hypoeutectic is much easier, surely superior in strength, toughness, and slidability, and has little variation in mechanical properties due to thickness. Spheroidal graphite cast iron castings can be produced.
また請求項４に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、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、成分組成において、ＣｕとＮｉの何れか１つ若しくは両方を総量で０．０１〜２．０質量％含有させることにより、より黒鉛化の促進を図ることができ、容易に黒鉛の面積率が小さく、黒鉛球状化率が高い、高ヤング率を有する、強度、靱性、摺動性に優れた亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
また請求項５に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項４に記載の構成による作用効果に加えて、Ｎｉを０．０１〜２．０質量％、ＣｕとＮｉの総量を０．０１〜２．０質量％とすることにより、より一層、黒鉛化の促進を図ることができ、確実に黒鉛面積率が小さく、黒鉛球状化率が高い、高ヤング率の亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
また請求項６に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項５に記載の構成による作用効果に加えて、Ｎｉを０．０５〜１．６質量％、Ｃｕを０．０５〜１．６質量％、ＣｕとＮｉの総量を０．１〜２．０質量％とすることにより、更に一層、黒鉛化の促進を図ることができ、より確実に黒鉛面積率が小さく、黒鉛球状化率が高い、高ヤング率の亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
また請求項７に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項６に記載の構成による作用効果に加えて、Ｎｉを０．１〜１．２質量％、Ｃｕを０．１〜１．２質量％、ＣｕとＮｉの総量を０．２〜１．６質量％とすることにより、更により一層、黒鉛化の促進を図ることができ、更により確実に黒鉛面積率が小さく、黒鉛球状化率が高い、高ヤング率の亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
According to the method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 4, in addition to the operational effects of the configuration according to any of claims 1 to 3, any one of Cu and Ni is used in the component composition. By containing one or both in a total amount of 0.01 to 2.0% by mass, graphitization can be further promoted, the area ratio of graphite is easily small, and the graphite spheroidization ratio is high. A hypoeutectic spheroidal graphite cast iron casting having a Young's modulus and excellent in strength, toughness, and slidability can be produced.
Moreover, according to the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of Claim 5, in addition to the effect by the structure of the said Claim 4, Ni is 0.01-2.0 mass%, Cu and By making the total amount of Ni 0.01-2.0% by mass, graphitization can be further promoted, the graphite area ratio is small, the graphite spheroidization ratio is high, and the high Young's modulus is high. It becomes possible to produce hypoeutectic spheroidal graphite cast iron castings.
Moreover, according to the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of Claim 6, in addition to the effect by the structure of the said Claim 5, 0.05-1.6 mass% of Ni, Cu is added. By making 0.05-1.6 mass% and the total amount of Cu and Ni 0.1-2.0 mass%, it is possible to further promote the graphitization, and the graphite area ratio is more reliably increased. It is possible to produce a hypoeutectic spheroidal graphite cast iron casting which is small and has a high graphite spheroidization ratio and a high Young's modulus.
Moreover, according to the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of Claim 7, in addition to the effect by the structure of the said Claim 6, 0.1-1.2 mass% of Ni, Cu is added. By making the total amount of 0.1 to 1.2% by mass and Cu and Ni 0.2 to 1.6% by mass, it is possible to further promote the graphitization, and more reliably the graphite area. It becomes possible to produce a hypoeutectic spheroidal graphite cast iron casting having a low rate and a high graphite spheroidization rate and a high Young's modulus.
また請求項８に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項１〜７の何れかに記載の構成による作用効果に加えて、Ｃを１．５〜２．５質量％、Ｓｉを１．６〜４．０質量％とすることで、基地中の黒鉛面積率が小さく、黒鉛球状化率の高い、より高ヤング率の亜共晶球状黒鉛鋳鉄鋳物を、更により確実に製造することが可能となる。
また請求項９に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項８に記載の構成による作用効果に加えて、Ｃを１．５〜２．４質量％、Ｓｉを１．８〜３．５質量％とすることで、基地中の黒鉛面積率が小さく、黒鉛球状化率の高い、より高ヤング率の亜共晶球状黒鉛鋳鉄鋳物を、より一層確実に製造することが可能となる。
また請求項１０に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法によれば、上記請求項１〜９の何れかに記載の構成による作用効果に加えて、Ｍｎを１．０質量％未満とすることで、共晶セメンタイトの晶出を抑制することができ、黒鉛化が十分になされた亜共晶球状黒鉛鋳鉄鋳物を製造することが可能となる。
Further, according to the method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 8, in addition to the function and effect of the structure according to any one of claims 1 to 7, C is 1.5 to 2.5. By making the mass% and Si 1.6 to 4.0 mass%, a hypoeutectic spheroidal graphite cast iron casting having a higher Young's modulus with a small graphite area ratio in the matrix and a high graphite spheroidization ratio can be obtained. Thus, it is possible to manufacture with certainty.
Further, according to the method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 9, in addition to the function and effect of the configuration according to claim 8, C is 1.5 to 2.4 mass%, Si is By setting the ratio to 1.8 to 3.5% by mass, a hypoeutectic spheroidal graphite cast iron casting with a lower Young's modulus and a higher graphite spheroidization ratio and a higher graphite spheroidization ratio is more reliably produced. It becomes possible.
Moreover, according to the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting according to claim 10, in addition to the function and effect of the configuration according to any one of claims 1 to 9, Mn is less than 1.0% by mass. By doing so, crystallization of eutectic cementite can be suppressed, and it becomes possible to produce a hypoeutectic spheroidal graphite cast iron casting that has been sufficiently graphitized.
本発明の亜共晶球状黒鉛鋳鉄鋳物の製造方法について、使用する亜共晶鋳鉄材料の成分組成における各成分元素の含有範囲について以下に説明する。なお、以下において含有量は質量％で記載する。 About the manufacturing method of the hypoeutectic spheroidal graphite cast iron casting of this invention, the containing range of each component element in the component composition of the hypoeutectic cast iron material to be used is demonstrated below. In addition, content is described in the mass% below.
Ｃの含有量は、１．５〜２．７％とする。
亜共晶鋳鉄のＣの含有量は、前提として４．３％未満ということになるが、Ｃの含有量が多くなりすぎると、黒鉛面積率が増加して、機械的性質が劣る。このためＣの含有量は、２．７％以下とする。
Ｃの含有量が２．７％を超えると、基地中の黒鉛の量が多くなって黒鉛面積率が９％を超え易く、そうなると機械的性質としてのヤング率が１８０ＧＰａ未満になり易い。またＣの含有量が１．５％未満では、黒鉛が晶出し難くなり、遊離セメンタイトが生成する。
Ｃの含有量は、得られる亜共晶球状黒鉛鋳鉄鋳物が黒鉛面積率９％以下、ヤング率が１８０ＧＰａ以上となることを考慮して、１．５〜２．５％がより好ましく、更に好ましくは１．５〜２．４％とするのがよい。
なお、ヤング率は黒鉛面積率の影響が大きいため、熱処理によって組織が変わってもヤング率に大きな影響はない。
The content of C is 1.5 to 2.7%.
The C content of hypoeutectic cast iron is assumed to be less than 4.3%, but if the C content is too large, the graphite area ratio increases and the mechanical properties are inferior. Therefore, the C content is 2.7% or less.
If the C content exceeds 2.7%, the amount of graphite in the matrix increases and the graphite area ratio tends to exceed 9%. If so, the Young's modulus as a mechanical property tends to be less than 180 GPa. On the other hand, if the C content is less than 1.5%, it is difficult to crystallize graphite and free cementite is generated.
The content of C is preferably 1.5 to 2.5%, more preferably, considering that the obtained hypoeutectic spheroidal graphite cast iron casting has a graphite area ratio of 9% or less and a Young's modulus of 180 GPa or more. Is preferably 1.5 to 2.4%.
Note that the Young's modulus is greatly affected by the graphite area ratio, so even if the structure is changed by heat treatment, the Young's modulus is not significantly affected.
Ｓｉの含有量は、１．０〜４．５％とする。
Ｓｉは強い黒鉛化作用があり、添加量の１／３の割合で炭素当量に含まれる。１．０％未満では黒鉛化作用を十分発揮させることができない。またＳｉはフェライト基地に固溶し、４．５％を超えると靱性を大きく下げる。
Ｓｉの含有量は、Ｃの黒鉛化促進と基地への固溶（靱性の低下を招く）を考慮して、１．６〜４．０％が好ましく、更に好ましくは１．８〜３．５％とするのがよい。
The Si content is 1.0 to 4.5%.
Si has a strong graphitizing action and is contained in the carbon equivalent at a rate of 1/3 of the added amount. If it is less than 1.0%, the graphitization effect cannot be sufficiently exhibited. Si dissolves in the ferrite matrix, and if it exceeds 4.5%, the toughness is greatly reduced.
The content of Si is preferably 1.6 to 4.0%, more preferably 1.8 to 3.5 in consideration of C graphitization promotion and solid solution in the base (causing a decrease in toughness). % Is good.
Ａｌの含有量は、０．０１〜０．２％とする。
本発明ではＡｌを添加、含有させるのが１つの特徴である。
ＡｌはＳｉと同様に、強い黒鉛化促進作用がある。また溶湯中の窒素濃度を下げ、セメンタイトの発生を抑制する作用がある。しかし０．２％以上添加すると、湯流れが悪くなる。また０．０１％未満では効果が薄い。
The Al content is set to 0.01 to 0.2%.
In the present invention, one feature is that Al is added and contained.
Al, like Si, has a strong graphitization promoting effect. It also has the effect of reducing the nitrogen concentration in the molten metal and suppressing the generation of cementite. However, if 0.2% or more is added, the hot water flow becomes worse. If the content is less than 0.01%, the effect is weak.
Ｍｇは黒鉛の球状化に用いる。
Ｍｇの含有量は０．０１５〜０．０６０％とする。
Ｍｇは溶湯中で気化し、その気泡中にＣが拡散して、球状黒鉛が生成されるため、必須である。０．０６０％を超えると、フェーディングが速く、温度の低下が大きくなるため、好ましくない。また０．０１５％未満では、黒鉛が自由に成長して片状になり易いので、好ましくない。
Mg is used for spheroidizing graphite.
The Mg content is 0.015 to 0.060%.
Mg is essential because it vaporizes in the molten metal and C diffuses into the bubbles to produce spherical graphite. If it exceeds 0.060%, fading is fast and the temperature decreases greatly, which is not preferable. On the other hand, if it is less than 0.015%, graphite is liable to grow freely into a piece, which is not preferable.
Ｎｉは黒鉛化促進作用やオーステナイト安定化作用がある。またフェライトに固溶して基地を強化する作用がある。従って必須ではないが、含有させるのがよい。
Ｎｉを含有させる場合は、０．０１〜２．０％とする。２．０％を超えると、フェライト基地の脆化につながる。また０．０１％未満では効果が薄い。
Ｎｉの含有量は、黒鉛化促進作用、オーステナイト安定化作用、基地強化作用、フェライト基地の脆化作用を考慮して、０．０５〜１．６％がより好ましく、更には０．１〜１．２％が最も好ましい。
Ni has a graphitization promoting effect and an austenite stabilizing effect. It also has the effect of strengthening the matrix by dissolving in ferrite. Therefore, although it is not essential, it is good to contain.
When Ni is contained, the content is set to 0.01 to 2.0%. If it exceeds 2.0%, the ferrite base becomes brittle. If the content is less than 0.01%, the effect is weak.
The content of Ni is more preferably 0.05 to 1.6% in consideration of the graphitization promoting effect, austenite stabilizing effect, matrix strengthening effect, and ferrite matrix embrittlement effect, and more preferably 0.1 to 1%. .2% is most preferred.
Ｃｕは黒鉛化促進作用やオーステナイト安定化作用がある。またパーライトのラメラ間隔を密にして、耐力を向上させる。よって必須ではないが、含有させるのがよい。
Ｃｕを含有させる場合は、０．０１〜２．０％とする。２．０％を超えるとパーライト基地を脆化し、靱性が低下し、また黒鉛球状化を阻害する。また０．０１％未満では効果が薄い。
Ｃｕの含有量は、黒鉛化促進作用、オーステナイト安定化作用、耐力向上作用、パーライト基地の脆化作用、黒鉛球状化阻害作用を考慮して、０．０５〜１．６％が好ましく、更には０．１〜１．２％が最も好ましい。
Cu has a graphitization promoting effect and an austenite stabilizing effect. In addition, the pearlite lamella spacing is increased to improve the yield strength. Therefore, although it is not essential, it is good to contain.
When Cu is contained, the content is 0.01 to 2.0%. If it exceeds 2.0%, the pearlite matrix becomes brittle, the toughness is lowered, and graphite spheroidization is inhibited. If the content is less than 0.01%, the effect is weak.
The content of Cu is preferably 0.05 to 1.6% in consideration of graphitization promoting effect, austenite stabilizing effect, yield strength improving effect, pearlite base embrittlement effect, graphite spheroidization inhibiting effect, 0.1 to 1.2% is most preferable.
ＮｉとＣｕは、何れも黒鉛化促進作用とオーステナイト安定化作用がある点で共通する。その合計、即ちＮｉ＋Ｃｕの合計としての含有は必須ではないが、上記ＮｉとＣｕの含有に伴って、Ｎｉ＋Ｃｕの合計量としても含有させることになる。
Ｎｉ＋Ｃｕの合計量としては、０．０１〜２．０％とする。０．０１％未満では黒鉛化促進効果が薄い。また２．０％を超えると基地の脆化につながる。
Ｎｉ＋Ｃｕの合計含有量は、黒鉛化促進作用、オーステナイト安定化作用、耐力向上作用、基地の強化と脆化の作用、黒鉛球状化阻害作用を考慮して、０．１〜２．０％がより好ましく、更には０．２〜１．６％が最も好ましい。
なお、ＣｕとＮｉのオーステナイト安定化作用は、熱処理をよりやり易くする効果があるので、含有させるのがよく、多く入れるほどその効果がより得られる。
Both Ni and Cu are common in that they have a graphitization promoting effect and an austenite stabilizing effect. Although the total content, that is, the total content of Ni + Cu is not essential, the total content of Ni + Cu is included with the content of Ni and Cu.
The total amount of Ni + Cu is 0.01 to 2.0%. If it is less than 0.01%, the graphitization promoting effect is small. If it exceeds 2.0%, the base will become brittle.
The total content of Ni + Cu is more preferably 0.1 to 2.0% in consideration of the graphitization promoting effect, austenite stabilizing effect, yield strength improving effect, base strengthening and embrittlement effect, and graphite spheroidization inhibiting effect. More preferably, 0.2 to 1.6% is most preferable.
In addition, since the austenite stabilizing action of Cu and Ni has an effect of facilitating heat treatment, it is preferable to contain it, and the more it is added, the more the effect is obtained.
Ｍｎは炭化物を安定化させるので、なるべく含有させないのが好ましい。但し、実際には原料となる鉄屑から混入する場合が多い。混入量は１．０％未満にするのが好ましい。より好ましくは、０．５％未満とするのがよい。
また同様に、ＰやＳは実際の製品では、いわゆる不純物として混入され得るが、本発明ではそれらの不純物は、積極的に含有させる対象ではない。
Since Mn stabilizes the carbide, it is preferably not contained as much as possible. However, it is often mixed from iron scraps that are raw materials. The mixing amount is preferably less than 1.0%. More preferably, the content is less than 0.5%.
Similarly, P and S can be mixed as so-called impurities in an actual product. However, in the present invention, these impurities are not intended to be actively included.
上記各添加元素の含有量の残部がＦｅである。
なお黒鉛化促進のため、Ｚｒ、Ｃａ、Ｂａ等を含有する接種剤を溶湯に添加するようにしてもよい。
The balance of the content of each additive element is Fe.
In order to accelerate graphitization, an inoculum containing Zr, Ca, Ba or the like may be added to the molten metal.
本発明の亜共晶球状黒鉛鋳鉄鋳物の製造について説明する。
先ず上記で説明した亜共晶球状黒鉛鋳鉄の成分組成を持つように原料を調整し、これを電気炉に入れ、１３５０〜１５５０℃で１時間溶融し、その後１５５０℃で取鍋に移して黒鉛球状化処理を施し、１４５０℃で鋳型に鋳込む。Ａｌは溶解後に溶湯に添加する。また必要に応じて、Ｚｒ、Ｃａ、Ｂａ等を含有する接種剤を鋳込む。その後、所定の形状に鋳込む。
鋳放し状態の鋳物の組織は、球状黒鉛とフェライト、若しくは球状黒鉛とフェライトとパーライト、若しくは球状黒鉛とパーライトとなる。
The production of the hypoeutectic spheroidal graphite cast iron casting of the present invention will be described.
First, the raw material is adjusted so as to have the component composition of hypoeutectic spheroidal graphite cast iron described above, and this is put into an electric furnace, melted at 1350 to 1550 ° C. for 1 hour, and then transferred to a ladle at 1550 ° C. A spheroidizing treatment is applied and cast into a mold at 1450 ° C. Al is added to the molten metal after melting. If necessary, an inoculum containing Zr, Ca, Ba or the like is cast. Then, it casts into a predetermined shape.
The structure of the as-cast product is spherical graphite and ferrite, or spherical graphite and ferrite and pearlite, or spherical graphite and pearlite.
図１も参照して、鋳放し状態の鋳物を出発鋳物として、以下の１段階の熱処理を行う。 Referring also to FIG. 1, the following one-stage heat treatment is performed using an as-cast casting as a starting casting.
［昇温処理］
上記の鋳込み工程で得られた鋳放し状態の鋳造品を用い、先ず所定の昇温処理を経て、熱処理温度まで昇温する。
昇温処理は２００℃／時間以下の昇温処理速度で行う。
昇温処理速度が速すぎると、昇温時に球状黒鉛から離れた遠い位置にある基地が十分にフェライトにならず、そのフェライトのなりきれなかった部分がオーステナイト化してしまう。昇温処理速度が速い場合、昇温速度に対する基地の温度上昇にタイムラグが生じる。また薄肉の場合と厚肉の場合においても、基地の温度上昇に差が生じ易くなる。
基地の温度上昇が速すぎると、特に球状黒鉛から離れた位置にあるパーライトからのフェライト発生が十分に行われず、パーライトがそのままオーステナイトになってしまう。
昇温処理速度を遅くすることで、パーライトからのフェライト発生を十分に促すと共に、肉厚差によるフェライト発生量のバラツキを解消することができる。
昇温処理速度は、以上のような理由から、より好ましくは１５０℃／時間以下とするのがよく、更に好ましくは１００℃／時間以下とするのがよい。
[Temperature rise processing]
Using the cast product in the as-cast state obtained in the casting step, the temperature is first raised to a heat treatment temperature through a predetermined temperature raising treatment.
The temperature increase process is performed at a temperature increase rate of 200 ° C./hour or less.
If the temperature raising treatment rate is too high, the base at a distant position away from the spherical graphite at the time of temperature rise will not sufficiently become ferrite, and the portion where the ferrite cannot be completed will be austenitic. When the temperature raising processing speed is high, a time lag occurs in the temperature rise of the base with respect to the temperature raising speed. In addition, the difference in temperature rise between bases is likely to occur between thin and thick cases.
When the temperature rise at the base is too fast, ferrite is not sufficiently generated from the pearlite at a position apart from the spherical graphite, and the pearlite becomes austenite as it is.
By slowing the temperature increase processing rate, it is possible to sufficiently promote the generation of ferrite from pearlite and to eliminate the variation in the amount of ferrite generated due to the difference in thickness.
For the reasons described above, the temperature raising treatment rate is more preferably 150 ° C./hour or less, and still more preferably 100 ° C./hour or less.
［熱処理］
熱処理は、７８０℃〜８７０℃で行う。定性的に言えば、亜共晶球状黒鉛鋳鉄組成の鋳物が、状態図上において、フェライトとオーステナイトとの共存状態となるような温度で熱処理を行う。
この熱処理温度は、フェライトとオーステナイトの共存状態がより好ましく得られることを考慮して、７８０〜８５０℃がより好ましく、更に好ましくは８００〜８５０℃とするのがよい。
前記熱処理温度での保持時間は、例えば３０分〜１５時間とすることができる。好ましくは、基地組織のフェライト化が十分に行え、且つ無駄な加熱エネルギーの低減のため、１〜１０時間がよく、更に好ましくは１〜６時間がよい。
熱処理により、組織は球状黒鉛と、熱処理温度に応じたフェライトとオーステナイトの比率（Ｆ：Ａ率）、若しくはそれに近いＦ：Ａ率の基地とからなる。
[Heat treatment]
The heat treatment is performed at 780 ° C to 870 ° C. Qualitatively speaking, heat treatment is performed at a temperature such that a hypoeutectic spheroidal graphite cast iron composition casting is in a state of coexistence of ferrite and austenite on the phase diagram.
This heat treatment temperature is more preferably 780 to 850 ° C., more preferably 800 to 850 ° C., considering that a coexistence state of ferrite and austenite is more preferably obtained.
The holding time at the heat treatment temperature can be, for example, 30 minutes to 15 hours. Preferably, 1 to 10 hours is preferable, and 1 to 6 hours is more preferable for sufficient ferritization of the base structure and reduction of useless heating energy.
By the heat treatment, the structure is composed of spherical graphite and a base of F: A ratio (F: A ratio) or a ratio of ferrite and austenite corresponding to the heat treatment temperature.
［冷却処理］
前記熱処理が終了すると、冷却処理を行う。
冷却処理は、上記熱処理によりフェライトとオーステナイトとの比率が安定した組織におけるオーステナイトを、パーライトと冷却処理中に生じたフェライトとからなる組織にする。
冷却処理速度が炉冷等、遅すぎる場合には、オーステナイトのフェライト化が進んで、組織が不均一になってしまう。一方、水冷等、速すぎる場合は、オーステナイトがマルテンサイトに変態してしまうため、組織の脆化につながり、好ましくない。
冷却処理速度は、マルテンサイト変態が生じない程度に速い冷却処理速度として、例えば強制空冷程度が好ましいと言える。
冷却処理速度は、数値的には０．５〜６０℃／分とする。冷却処理は、鋳物が常温になるまで行う。
冷却処理速度は、オーステナイトのフェライト化防止、マルテンサイトの発生防止の観点から、好ましくは０．５〜３０℃／分がよく、更に好ましくは１〜３０℃／分がよい。
[Cooling treatment]
When the heat treatment is completed, a cooling process is performed.
In the cooling treatment, austenite in a structure in which the ratio of ferrite and austenite is stabilized by the heat treatment is changed to a structure composed of pearlite and ferrite generated during the cooling treatment.
If the cooling treatment rate is too slow, such as furnace cooling, the austenite becomes ferritic and the structure becomes non-uniform. On the other hand, if it is too fast, such as water cooling, austenite is transformed into martensite, leading to embrittlement of the structure, which is not preferable.
It can be said that the cooling processing speed is preferably, for example, forced air cooling, as a cooling processing speed that is high enough not to cause martensitic transformation.
The cooling processing speed is numerically set to 0.5 to 60 ° C./min. The cooling process is performed until the casting reaches room temperature.
The cooling treatment rate is preferably 0.5 to 30 ° C./min, more preferably 1 to 30 ° C./min, from the viewpoint of preventing austenite from becoming ferritic and preventing martensite.
以上のようにして、鋳放し状態の鋳物を１回の熱処理をすることにより、組織中のフェライトとパーライトの比率を一定にすることができ、鋳物の肉厚差によらず、硬度の安定した、亜共晶球状黒鉛鋳鉄鋳物を得ることができる。またフェライトとパーライトの比率を熱処理の時間を調整することで、硬度の異なる鋳物を安定して提供できる。
また本発明の成分組成と熱処理により、強度、靱性（衝撃特性）、摺動性に優れると共に、肉厚差による機械的性質のバラツキが少ない、亜共晶球状黒鉛鋳鉄鋳物を安定して提供できる。
As described above, the ratio of the ferrite and pearlite in the structure can be made constant by subjecting the as-cast casting to one heat treatment, and the hardness is stable regardless of the thickness difference of the casting. A hypoeutectic spheroidal graphite cast iron casting can be obtained. Further, by adjusting the ratio of ferrite and pearlite to the heat treatment time, castings having different hardnesses can be provided stably.
In addition, the component composition and heat treatment of the present invention can stably provide hypoeutectic spheroidal graphite cast iron castings that are excellent in strength, toughness (impact characteristics), and slidability, and have little variation in mechanical properties due to thickness differences. .
組成にＳｉが入ると、通常のＦｅやＦｅ−Ｃ系状態図で存在しないフェライトとオーステナイトの共存領域が存在するようになる。その共存領域はＳｉの含有量が多いほど広がる。共存領域の温度で保持を行うと、その保持温度に応じたフェライトとオーステナイトの比率となるため、肉厚や黒鉛粒数に関係なく組織が均一になる。ある程度の保持時間が必要となるのは、その温度に応じた組織状態になるのに時間が必要であるからである。
また前記共存領域の中で、温度の高い領域ではオーステナイトの割合が大きく、オーステナイトは冷却処理時に硬いパーライトになるため、硬めの組織になり、高強度の機械的性質を持つことになる。同様に、前記共存領域の中で温度の低い領域では、軟らかいフェライトの割合が多くなり、延性の良い組織になる。
When Si enters the composition, there exists a coexistence region of ferrite and austenite that does not exist in a normal Fe or Fe-C phase diagram. The coexistence region expands as the Si content increases. When holding at the temperature of the coexistence region, the ratio of ferrite and austenite according to the holding temperature is obtained, so that the structure becomes uniform regardless of the thickness and the number of graphite grains. The reason why a certain holding time is required is that it takes time to obtain a tissue state corresponding to the temperature.
Further, in the coexisting region, the proportion of austenite is large in the region where the temperature is high, and austenite becomes hard pearlite during the cooling treatment, so that it becomes a hard structure and has high strength mechanical properties. Similarly, in the region where the temperature is low in the coexisting region, the proportion of soft ferrite increases, and a structure with good ductility is obtained.
表１を参照して、実施例１〜９、比較例１の各亜共晶球状黒鉛鋳鉄材料を、電気炉で１３５０〜１５５０℃で約１時間溶融し、これを１５５０℃で取鍋に移した後、球状化処理を施した後、１４５０℃で鋳型に鋳造した。実施例１〜９、比較例１のそれぞれにつき、肉厚が５ｍｍの鋳物、１０ｍｍの鋳物、５０ｍｍの鋳物、の３種類の鋳物を鋳造した。
実施例１〜９、比較例１の成分組成を表１に示す。
Referring to Table 1, the hypoeutectic spheroidal graphite cast iron materials of Examples 1 to 9 and Comparative Example 1 were melted in an electric furnace at 1350 to 1550 ° C. for about 1 hour, and transferred to a ladle at 1550 ° C. Then, after spheroidizing treatment, it was cast into a mold at 1450 ° C. For each of Examples 1 to 9 and Comparative Example 1, three types of castings were cast: a casting having a thickness of 5 mm, a casting of 10 mm, and a casting of 50 mm.
The component compositions of Examples 1 to 9 and Comparative Example 1 are shown in Table 1.
次に図１、表２に示すように、各実施例１〜９について、鋳放し状態の鋳物に対する熱処理をした。この場合の熱処理は１回である。先ず昇温処理をする。
熱処理は、実施例１については、１００℃／時間の昇温処理速度で、８５０℃の熱処理温度（α＋γ温度）まで昇温し、その熱処理温度で２時間保持した後、各肉厚５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれの冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで冷却処理を行った。
実施例２と実施例３については、５０℃／時間の昇温処理速度で、８３０℃の熱処理温度（α＋γ温度）まで昇温し、その熱処理温度で３時間保持した後、各肉厚５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれ同様に冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで冷却処理を行った。
実施例４と実施例５については、３０℃／時間の昇温処理速度で、実施例４は８２０℃、実施例５は８００℃の熱処理温度（α＋γ温度）まで昇温し、それぞれの熱処理温度で４時間保持した後、各肉厚５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれ同様に冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで冷却処理を行った。
実施例６については、前記実施例２、３と同様に、５０℃／時間の昇温処理速度で、８３０℃の熱処理温度（α＋γ温度）まで昇温し、その熱処理温度で３時間保持した後、各肉厚５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれ同様に冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで冷却処理を行った。
実施例７、８、９については、前記実施例１と同様に、１００℃／時間の昇温処理速度で、８５０℃の熱処理温度（α＋γ温度）まで昇温し、その熱処理温度で２時間保持した後、各肉厚５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれ同様に冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで冷却処理を行った。
Next, as shown in FIG. 1 and Table 2, in each of Examples 1 to 9, heat treatment was performed on the casting in an as-cast state. In this case, the heat treatment is performed once. First, the temperature raising process is performed.
In Example 1, with respect to Example 1, the temperature was increased to a heat treatment temperature (α + γ temperature) of 850 ° C. at a temperature increase treatment rate of 100 ° C./hour, and held at the heat treatment temperature for 2 hours. , 50 mm, the cooling treatment was performed at respective cooling treatment speeds of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim.
About Example 2 and Example 3, it heated up to 830 degreeC heat processing temperature ((alpha) + (gamma) temperature) with the temperature increase processing rate of 50 degreeC / hour, and after maintaining at the heat processing temperature for 3 hours, each thickness 5mm, 10 mm and 50 mm were similarly subjected to cooling treatment at cooling treatment rates of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim, respectively.
For Example 4 and Example 5, the temperature was increased to a heat treatment temperature (α + γ temperature) of 820 ° C. and Example 5 of 800 ° C. at a temperature increase rate of 30 ° C./hour. Then, for each thickness of 5 mm, 10 mm, and 50 mm, the cooling treatment was similarly performed at the cooling treatment speeds of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim, respectively.
For Example 6, as in Examples 2 and 3, the temperature was raised to a heat treatment temperature (α + γ temperature) of 830 ° C. at a temperature raising treatment rate of 50 ° C./hour, and held at that heat treatment temperature for 3 hours. Each of the wall thicknesses of 5 mm, 10 mm, and 50 mm was similarly cooled at a cooling rate of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim.
For Examples 7, 8, and 9, as in Example 1, the temperature was increased to a heat treatment temperature (α + γ temperature) of 850 ° C. at a temperature increase rate of 100 ° C./hour and held at that heat treatment temperature for 2 hours. After that, each of the thicknesses of 5 mm, 10 mm, and 50 mm was similarly cooled at a cooling treatment rate of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim.
図２、表３に示すように、比較例１についても、鋳放し状態の鋳物に対する熱処理を２回の熱処理からなる処理を行った。先ず１回目はオーステナイト化処理として、電気炉内で１００℃／時間で昇温し、１０００℃（γ温度）で２時間保持（γ保持時間）した。次に比較例１の各肉厚５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれの冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで一旦常温まで冷却処理した。組織はフェライトとパーライトと球状黒鉛とになる。次に２回目の熱処理は、パーライト中のセメンタイトの粒状化（黒鉛化）処理として、再び電気炉内で１００℃／時間で昇温し、６５０℃（粒状化温度）で５時間保持（保持時間）し、その後、比較例１の各厚み５ｍｍ、１０ｍｍ、５０ｍｍにつき、それぞれの冷却処理速度１℃／ｍｉｍ、３℃／ｍｉｍ、３０℃／ｍｉｍで常温まで冷却処理した。 As shown in FIG. 2 and Table 3, also in Comparative Example 1, the heat treatment for the as-cast product was performed by two heat treatments. First, as the austenitizing treatment, the temperature was raised at 100 ° C./hour in an electric furnace and held at 1000 ° C. (γ temperature) for 2 hours (γ holding time). Next, each thickness 5 mm, 10 mm, and 50 mm of Comparative Example 1 was once cooled to room temperature at a cooling processing rate of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim. The structure is ferrite, pearlite, and spherical graphite. Next, the second heat treatment is a granulation (graphitization) treatment of cementite in pearlite. The temperature is again raised at 100 ° C./hour in an electric furnace, and held at 650 ° C. (granulation temperature) for 5 hours (retention time). Then, each thickness 5 mm, 10 mm, and 50 mm of Comparative Example 1 was cooled to room temperature at a cooling processing rate of 1 ° C./mim, 3 ° C./mim, and 30 ° C./mim.
得られた熱処理済みの実施例１〜９、比較例１における、各鋳物の肉厚毎の黒鉛粒数（個／ｍｍ２）、黒鉛面積率（％）、フェライト／パーライト率（Ｆ：Ｐ率）（％）、硬さ（ＨＲＢ）を計測した。
結果を表４に示す。
また各実施例１〜９、比較例１についての機械的性質として、肉厚１０ｍｍのものにおける０．２％耐力（Ｎ／ｍｍ２）、ヤング率（ＧＰａ）、引張強さ（Ｎ／ｍｍ２）、伸び（％）を、併せて表４に示す。
In heat-treated Examples 1 to 9 and Comparative Example 1 obtained, the number of graphite grains per piece thickness (pieces / mm 2 ), graphite area ratio (%), ferrite / pearlite ratio (F: P ratio) ) (%) And hardness (HRB) were measured.
The results are shown in Table 4.
As the mechanical properties for each of Examples 1-9, Comparative Example 1, 0.2% proof stress of definitive to those thick 10mm (N / mm 2), the Young's modulus (GPa), tensile strength (N / mm 2 ) And elongation (%) are shown together in Table 4.
比較例１では、１回目の熱処理が終了した時点で、組織が球状化黒鉛と、フェライトとパーライトとの基地組織とになり、２回目の熱処理により、基地中のパーライトのセメンタイトが分解して黒鉛化し、徐々に硬さが減少する。
よって比較例１の鋳物は、伸びはよいが、強度が低くなる。表４では引張強さが７１６．３（Ｎ／ｍｍ２）で低い。
また比較例１では、組織変化が黒鉛粒数に依存するため、黒鉛粒数が肉厚差により変化（４１３個、３３５個、９８個）すると、実際には肉厚差で組織が変化し、そのため表４に示すように、肉厚差による硬度変化（８９、９１、９５ＨＲＢ）が生じる。即ち、肉厚差で機械的強度が変化し易い。
In Comparative Example 1, when the first heat treatment is completed, the structure becomes a spheroidized graphite and a base structure of ferrite and pearlite, and by the second heat treatment, pearlite cementite in the matrix is decomposed and graphite. And gradually decreases in hardness.
Therefore, the casting of Comparative Example 1 has good elongation but low strength. In Table 4, the tensile strength is 716.3 (N / mm 2 ), which is low.
Further, in Comparative Example 1, since the structure change depends on the number of graphite grains, when the number of graphite grains changes due to the thickness difference (413, 335, 98), the structure actually changes due to the thickness difference, Therefore, as shown in Table 4, a change in hardness (89, 91, 95 HRB) due to the difference in thickness occurs. That is, the mechanical strength is likely to change due to the thickness difference.
表２、表４を参照して、実施例１〜９において、肉厚毎の黒鉛粒数は、肉厚が５ｍｍ、１０ｍｍ、５０ｍｍと厚肉になるにつれて、減少している。その一方、基地中のフェライト／パーライト率（Ｆ：Ｐ率）は、肉厚の変化によるも、変化が少ないことがわかる。
また同様に、実施例１〜９においては、肉厚が５ｍｍ、１０ｍｍ、５０ｍｍと変化しても、硬度（ＨＲＢ）の変化は少ないことがわかる。その理由は、本発明では、肉厚差による冷却速度等の変化によって黒鉛粒数や黒鉛寸法に変化が生じても、鋳物基地のおけるフェライトとパーライトとの比率を一定にすることができ、基地の硬度を肉厚差によらず安定させることができるからである。
実施例１〜９では、全体として引張強度が大であり、しかも伸びも良好であることがわかる。即ち、実施例１〜９においては、何れも引張強さが８３０Ｎ／ｍｍ２以上で、伸びも９．０％以上の良好な機械的性質を示している。
実施例１〜９では、熱処理温度が８５０℃〜８００℃の範囲で温度が下がると、フェライト量が低下し、パーライト量が増加する傾向がわかる。またそれに伴って、パーライト量が増加するにつれて、硬度、引張強さが増加する傾向がわかる。
Referring to Tables 2 and 4, in Examples 1 to 9, the number of graphite particles for each thickness decreases as the thickness becomes 5 mm, 10 mm, and 50 mm. On the other hand, it can be seen that the ferrite / pearlite ratio (F: P ratio) in the base is little changed even when the thickness is changed.
Similarly, in Examples 1 to 9, even when the wall thickness is changed to 5 mm, 10 mm, and 50 mm, it is understood that the change in hardness (HRB) is small. The reason for this is that, in the present invention, even if the number of graphite grains or the size of the graphite changes due to the change in the cooling rate due to the difference in thickness, the ratio of ferrite and pearlite in the casting base can be made constant. This is because the hardness can be stabilized regardless of the thickness difference.
In Examples 1-9, it turns out that tensile strength is large as a whole, and also elongation is also favorable. That is, in Examples 1 to 9, all show good mechanical properties with a tensile strength of 830 N / mm 2 or more and an elongation of 9.0% or more.
In Examples 1-9, when the temperature falls in the range of 850 ° C. to 800 ° C., the ferrite amount decreases and the pearlite amount increases. Along with this, it can be seen that the hardness and tensile strength tend to increase as the amount of pearlite increases.
Claims (10)
Ｃ ：１．５〜２．７％
Ｓｉ ：１．０〜４．５％
Ａｌ ：０．０１〜０．２％
Ｍｇ ：０．０１５〜０．０６０％
を含有し、残部がＦｅからなる成分組成を有し、
溶湯から一旦鋳造してなる出発鋳物を、先ず常温から２００℃／時間以下の昇温処理速度で、７８０〜８７０℃の熱処理温度まで昇温し、該熱処理温度で０．５〜１５時間保持して、基地をフェライトとオーステナイトからなる組織とし、次に前記熱処理温度から０．５〜６０℃／分の冷却処理速度により常温まで冷却して、オーステナイトからパーライトとフェライトを析出させ、基地をフェライトとパーライトからなる組織とすることを特徴とする亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.7%
Si: 1.0 to 4.5%
Al: 0.01 to 0.2%
Mg: 0.015-0.060%
And the balance has a component composition consisting of Fe,
A starting casting once cast from the molten metal is first heated from room temperature to a heat treatment temperature of 780 to 870 ° C. at a heating rate of 200 ° C./hour or less, and held at the heat treatment temperature for 0.5 to 15 hours. The matrix is composed of ferrite and austenite, and then cooled from the heat treatment temperature to room temperature at a cooling rate of 0.5 to 60 ° C./min to precipitate pearlite and ferrite from the austenite. A method for producing a hypoeutectic spheroidal graphite cast iron casting, characterized by having a structure comprising pearlite.
Ｃ ：１．５〜２．７％
Ｓｉ ：１．０〜４．５％
Ａｌ ：０．０１〜０．２％
Ｃｕ＋Ｎｉ ：０．０１〜２．０％
Ｍｇ ：０．０１５〜０．０６０％
を含有し、残部がＦｅからなる成分組成を有することを特徴とする請求項１〜３の何れかに記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.7%
Si: 1.0 to 4.5%
Al: 0.01 to 0.2%
Cu + Ni: 0.01 to 2.0%
Mg: 0.015-0.060%
The method for producing a hypoeutectic spheroidal graphite cast iron casting according to any one of claims 1 to 3, wherein the remaining component has a composition composed of Fe.
Ｃ ：１．５〜２．７％
Ｓｉ ：１．０〜４．５％
Ａｌ ：０．０１〜０．２％
Ｎｉ ：０．０１〜２．０％
Ｃｕ＋Ｎｉ ：０．０１〜２．０％
Ｍｇ ：０．０１５〜０．０６０％
を含有し、残部がＦｅからなる成分組成を有することを特徴とする請求項４に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.7%
Si: 1.0 to 4.5%
Al: 0.01 to 0.2%
Ni: 0.01 to 2.0%
Cu + Ni: 0.01 to 2.0%
Mg: 0.015-0.060%
5. The method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 4, wherein the composition has a composition comprising Fe and the balance being Fe.
Ｃ ：１．５〜２．７％
Ｓｉ ：１．０〜４．５％
Ａｌ ：０．０１〜０．２％
Ｎｉ ：０．０５〜１．６％
Ｃｕ ：０．０５〜１．６％
Ｃｕ＋Ｎｉ ：０．１〜２．０％
Ｍｇ ：０．０１５〜０．０６０％
を含有し、残部がＦｅからなる成分組成を有することを特徴とする請求項５に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.7%
Si: 1.0 to 4.5%
Al: 0.01 to 0.2%
Ni: 0.05-1.6%
Cu: 0.05 to 1.6%
Cu + Ni: 0.1-2.0%
Mg: 0.015-0.060%
6. The method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 5, wherein the composition has a composition comprising Fe and the balance being Fe.
Ｃ ：１．５〜２．７％
Ｓｉ ：１．０〜４．５％
Ａｌ ：０．０１〜０．２％
Ｎｉ ：０．１〜１．２％
Ｃｕ ：０．１〜１．２％
Ｃｕ＋Ｎｉ ：０．２〜１．６％
Ｍｇ ：０．０１５〜０．０６０％
を含有し、残部がＦｅからなる成分組成を有することを特徴とする請求項６に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.7%
Si: 1.0 to 4.5%
Al: 0.01 to 0.2%
Ni: 0.1-1.2%
Cu: 0.1-1.2%
Cu + Ni: 0.2 to 1.6%
Mg: 0.015-0.060%
The method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 6, wherein the composition has a composition comprising Fe, with the balance being Fe.
Ｃ ：１．５〜２．５％
Ｓｉ ：１．６〜４．０％
とすることを特徴とする請求項１〜７の何れかに記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.5%
Si: 1.6-4.0%
The method for producing a hypoeutectic spheroidal graphite cast iron casting according to any one of claims 1 to 7.
Ｃ ：１．５〜２．４％
Ｓｉ ：１．８〜３．５％
とすることを特徴とする請求項８に記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
C: 1.5 to 2.4%
Si: 1.8-3.5%
The method for producing a hypoeutectic spheroidal graphite cast iron casting according to claim 8.
Ｍｎ ：１．０％未満
とすることを特徴とする請求項１〜９の何れかに記載の亜共晶球状黒鉛鋳鉄鋳物の製造方法。 In weight percent,
The method for producing a hypoeutectic spheroidal graphite cast iron casting according to any one of claims 1 to 9, wherein Mn is less than 1.0%.
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| JPS51123719A (en) * | 1975-04-22 | 1976-10-28 | Katsuya Igawa | Tough spherical graphite cast-iron and heat treatment thereof |
| JPS5262116A (en) * | 1975-11-17 | 1977-05-23 | Kashiya Igawa | High strength spherulitic graphite cast iron and heat treatment for the same |
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| WO2011145194A1 (en) * | 2010-05-20 | 2011-11-24 | 虹技株式会社 | Heat-resistant cast iron type metallic short fiber, and process for production thereof |
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