JP2677367B2 - Spheroidal graphite cast iron - Google Patents
Spheroidal graphite cast ironInfo
- Publication number
- JP2677367B2 JP2677367B2 JP62323813A JP32381387A JP2677367B2 JP 2677367 B2 JP2677367 B2 JP 2677367B2 JP 62323813 A JP62323813 A JP 62323813A JP 32381387 A JP32381387 A JP 32381387A JP 2677367 B2 JP2677367 B2 JP 2677367B2
- Authority
- JP
- Japan
- Prior art keywords
- impact value
- elongation
- cast iron
- spheroidal graphite
- graphite cast
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Landscapes
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は高靭性の球状黒鉛鋳鉄に関する。
［従来技術及び発明が解決しようとする問題点］
従来のフェライト地を有する球状黒鉛鋳鉄FCD37又はF
CD40は、ある程度伸び、衝撃値は高いが、低温における
衝撃値が低い。
これらを改善する為にNiを添加する方法が特公昭61−
33897等によって開示されている。しかしながら、この
発明ではSiが2.0％以上であるため−15℃で最低1.7kgf
−m/cm2の衝撃値しか得られない。
また、溶湯内にBiを含むフェロアロイを添加し、接種
して得られる球状黒鉛を含む鋳鉄が、特開昭58−45311
号公報に開示されている。
しかし、このものも、接種後の鋳鉄が2.2％以上のSi
を含有するため、硬度の上り、伸びの低下、衝撃値の低
下、特に極低温で衝撃値が低下する虞がある。
自動車用や産業用鋳物部品は最近−40℃程度の低温下
でも使用されることが多く、このような低温でも高い衝
撃値が要求されるようになった。
そこで本発明者等は、Si含有量を低くすることとBiを
微量添加することにより黒鉛粒数を300ケ/mm2以上に増
加させることにより伸びと衝撃値を向上させた。
また上記発明ではフェライト組織であることを条件と
し実施例ではフェライト化焼なましを行なっているが、
製造原価を低減する意味では焼なましを行なわず、鋳放
し状態で使用することが最も好ましい。
本発明では微量のBiを添加するために黒鉛粒数が増加
しパーライトが少なくなり、熱処理をしなくても、又は
熱処理をするとしても低温でかつ短時間の熱処理で充分
な伸びと衝撃値を確保し得ることを知見し本発明を完成
するに至ったものである。
もちろん焼なましを行なってフェライト組織にすれ
ば、更に高い伸びや靭性が得られることはいうまでもな
い。
本発明の目的は、伸びと衝撃値、特に低温での衝撃値
を向上せしめ、かつ熱処理を省くか、行っても低温でか
つ短時間の熱処理を行なうのみで製造原価を低減し得る
球状黒鉛鋳鉄を提供するものである。
［問題点を解決するための手段］
本発明の球状黒鉛鋳鉄は、
重量％で
C :3.0 〜4.0％
Si:1.5 〜2.0％未満
Mn: ＜0.3％
P : ＜0.03％
Cr: ＜0.10％
Mg:0.02〜0.06％
CE値（炭素当量＝Ｃ＋1/3×（Si＋Ｐ））:3.9〜4.6％
残余鉄及び不可避的不純物からなり、かつ上記組成の
溶湯に0.005〜0.03％のBiを添加し、該Bi添加と同時に
又は添加後に接種を行ない、黒鉛粒数を300ケ/mm2以
上、かつ−40℃における衝撃値が1.5kgf−m/cm2以上と
し、必要に応じてBiの残留含有量を0.0015〜0.150％と
したことを特徴とするものである。
次に前記数値の限定理由について説明する。
Ｃは3.0％未満では鋳造性が悪くなり、かつ黒鉛粒数
が減少するためパーライトが多くなる。また4.0％を超
えるとキッシュ黒鉛が出やすくなり強度が低下する。
Siは1.5％未満では炭化物が析出しやすくなり衝撃値
と伸びが低下する。また、2.0％を超えるとシリコフェ
ライトの影響で衝撃値や伸びが低下する。
Mnは0.3％を超えるとパーライトが多くなり衝撃値と
伸びが低下する。
Ｐは0.03％を超えるとステダイトの影響で衝撃値と伸
びが低下する。
Crが0.1％を超えると炭化物が析出しやすくなり衝撃
値と伸びが低下する。
Mgは0.02％未満では黒鉛が球状化せず、0.06％を超え
ると、ひけ巣、炭化物がでやすくなるばかりでなく、経
済的にも不利となる。
CE値は3.9％未満では炭化物が出やすくなり、また鋳
造性も悪くなる。4.6％を超えるとキッシュ黒鉛が出や
すくなる。
Biはその残留含有量が0.0015％未満では黒鉛粒数増大
効果が低下し、そのため鋳放し組織中にセメンタイトが
発生するようになる。
また残留含有量が0.0150％を超えると
Biの黒鉛球状化阻害効果が現出し、黒鉛の球状化率が
70％以下となって機械的諸性質が劣化する。
Biは球状黒鉛鋳鉄溶湯に対する溶け込み歩留まり率が
悪く、しかも変動も大きいため、その残留含有量を0.00
15〜0.0150％にするためには添加量として0.005〜0.030
％に設定する必要がある。
黒鉛粒数は、300ケ/mm2未満では、黒鉛間距離が大き
くなりパーライトの析出が多くなって衝撃値、伸びが低
下する。
［作 用］
本発明は、伸び、衝撃値、特に−40℃での衝撃値の高
い球状黒鉛鋳鉄が鋳放しでも得ることができる。
またフェライト化焼なまし熱処理を行なえば、更に高
い衝撃値、伸びが得られる。
［実施例.1］ 第１図（ａ），（ｂ），（ｃ），（ｄ）は顕微鏡組織
を示す。第１図（ａ）に示す本発明材は黒鉛粒数が多
く、かつフェライトが多いことがわかる。これにくらべ
て第１図（ｂ）に示す通常のFCD40は黒鉛粒数も少な
く、パーライトも多い。また第１図（ｃ）に示す低Si％
のFCD40は黒鉛粒数も少なく、かつパーライトは極めて
多い。第１図（ｄ）に示す通常のFCD40にBiを添加した
ものは黒鉛粒数は増えフェライトも多くなっていること
がわかる。
第２図、第３図に機械的性質を示す。本発明材の引張
り強さは43.5kgf/mm2,耐力は27.2kgf/mm2,伸びは23.8
％，室温における衝撃値は2.23kgf−m/cm2,−40℃にお
ける衝撃値は1.81kgf−m/cm2であり、引張強さ、耐力は
FCD40より低いが、伸び、衝撃値特に−40℃における衝
撃値は良好な値が得られる。
またFCD40で低Siにしたものは、顕微鏡組織でパーラ
イトが多いことより引張強さ耐力は高くなるが伸び、衝
撃値は著しく低くなる。またBiを添加した通常のSi％の
FCDは顕微鏡組織では黒鉛が微細化されフェライトが多
くなっているが、低Siの本発明材にくらべると伸び、衝
撃性は低い値となる。特に−40℃の低温衝撃値の著しい
改善は認められない。
このように本発明材は、従来の材質あるいは従来の材
質を低Si化するとか、Biを添加するとか改善をしたもの
にくらべて極めて優れた材質であることがわかる。
また熱処理を行なわなくても優れた材質が得られるこ
とがわかる。
［発明の効果］
以上の説明で明らかなように、本発明の球状黒鉛鋳鉄
は、Si値を低くし、しかも、微量のBiを添加することに
より、熱処理をしなくても、又は熱処理をするとしても
低温でかつ短時間の熱処理で、黒鉛粒数が増加すると共
に、フェライト率が向上し、パーライトが少なくなっ
て、充分な伸びと衝撃値を確保でき、シリコ・フェライ
トの悪影響、すなわち、硬度の上り，伸びの低下，衝撃
値の低下，特に、−40℃程度の極低温での衝撃値の低下
を少なくすることができる。
また、前述のとおり鋳放し状態で優れた引張強さ、伸
び及び衝撃値を有するものであるが、熱処理を施すと鋳
放し材に較べ、更に優れた伸び、衝撃値、特に低温での
衝撃値が改善される。
すなわち、球状黒鉛鋳鉄の機械的性質の向上と製造原
価の低減に著しい効果をもたらすものである。TECHNICAL FIELD The present invention relates to high-toughness spheroidal graphite cast iron. [Problems to be Solved by Prior Art and Invention] Spheroidal graphite cast iron FCD37 or F having a conventional ferrite material
CD40 has some elongation and high impact value, but low impact value at low temperature. To improve these, a method of adding Ni is disclosed in
33897 and the like. However, since Si is 2.0% or more in this invention, at least 1.7 kgf at -15 ° C.
Only an impact value of −m / cm 2 can be obtained. Further, cast iron containing spheroidal graphite obtained by adding a ferroalloy containing Bi to the molten metal and inoculating it is disclosed in JP-A-58-45311.
No. 6,086,045. However, this one also has a cast iron content of 2.2% or more after inoculation.
Since it contains, the hardness may increase, the elongation may decrease, the impact value may decrease, and particularly, the impact value may decrease at an extremely low temperature. Recently, automobile and industrial cast parts are often used even at a low temperature of about -40 ° C, and a high impact value is required even at such a low temperature. Therefore, the present inventors have improved the elongation and the impact value by decreasing the Si content and adding a small amount of Bi to increase the number of graphite particles to 300 pieces / mm 2 or more. Further, in the above invention, ferritizing annealing is performed in the examples on condition that the ferrite structure is used.
In order to reduce the manufacturing cost, it is most preferable to use the as-cast condition without annealing. In the present invention, the number of graphite particles is increased to reduce the pearlite due to the addition of a small amount of Bi, and even if the heat treatment is not performed, or even if the heat treatment is performed, a sufficient elongation and impact value can be obtained by the heat treatment at a low temperature and a short time. The present inventors have completed the present invention by finding that they can be secured. Needless to say, higher annealing and toughness can be obtained by annealing to obtain a ferrite structure. An object of the present invention is to improve elongation and impact value, particularly impact value at low temperature, and to reduce the manufacturing cost by omitting heat treatment or even performing heat treatment at low temperature and short time even if it is performed. Is provided. [Means for Solving the Problems] The spheroidal graphite cast iron of the present invention contains C: 3.0 to 4.0% Si: 1.5 to less than 2.0% by weight% Mn: <0.3% P: <0.03% Cr: <0.10% Mg : 0.02 to 0.06% CE value (carbon equivalent = C + 1/3 x (Si + P)): 3.9 to 4.6% It consists of residual iron and inevitable impurities, and 0.005 to 0.03% Bi is added to the molten metal having the above composition. Simultaneously with or after addition of Bi, inoculation is performed to set the number of graphite particles to 300 pieces / mm 2 or more, and the impact value at −40 ° C. to 1.5 kgf-m / cm 2 or more. It is characterized by being 0.0015 to 0.150%. Next, the reason for limiting the numerical values will be described. If C is less than 3.0%, castability will be poor and pearlite will increase due to a decrease in the number of graphite particles. On the other hand, if it exceeds 4.0%, quiche graphite tends to be produced, and the strength is reduced. If the content of Si is less than 1.5%, carbides are easily precipitated, and the impact value and elongation decrease. On the other hand, if it exceeds 2.0%, the impact value and elongation decrease due to the influence of silicoferrite. When Mn exceeds 0.3%, the amount of pearlite increases and the impact value and elongation decrease. When P exceeds 0.03%, impact value and elongation decrease due to the influence of steadite. If the Cr content exceeds 0.1%, carbides are easily precipitated, and the impact value and elongation decrease. If Mg is less than 0.02%, the graphite will not be spheroidized, and if it exceeds 0.06%, not only are sink marks and carbides easily generated, but also it is economically disadvantageous. When the CE value is less than 3.9%, carbides are easily generated, and castability is also deteriorated. If it exceeds 4.6%, quiche graphite is likely to be produced. If Bi has a residual content of less than 0.0015%, the effect of increasing the number of graphite particles is reduced, and as a result, cementite is generated in the as-cast structure. Also, when the residual content exceeds 0.0150%, the effect of inhibiting Bi spheroidization of graphite appears, and the spheroidization rate of graphite is increased.
It becomes 70% or less and various mechanical properties deteriorate. Bi has a low melt yield rate in molten spheroidal graphite cast iron, and its fluctuation is large.
In order to reach 15 to 0.0150%, add 0.005 to 0.030
Must be set to%. If the number of graphite particles is less than 300 pcs / mm 2 , the distance between the graphites will increase, and pearlite will increase, resulting in a decrease in impact value and elongation. [Operation] The present invention can obtain as-cast spheroidal graphite cast iron having high elongation, impact value, and particularly high impact value at -40 ° C. Further, a higher impact value and elongation can be obtained by performing a ferrite annealing heat treatment. [Example 1] FIGS. 1 (a), (b), (c) and (d) show microscopic structures. It can be seen that the material of the present invention shown in FIG. 1 (a) has a large number of graphite particles and a large amount of ferrite. Compared with this, the normal FCD40 shown in Fig. 1 (b) has a small number of graphite particles and a large amount of pearlite. In addition, the low Si% shown in Fig. 1 (c)
FCD40 has a small number of graphite particles and has an extremely large amount of perlite. It can be seen that the normal FCD40 shown in FIG. 1 (d) to which Bi is added has an increased number of graphite particles and an increased amount of ferrite. 2 and 3 show mechanical properties. The tensile strength of the material of the present invention is 43.5 kgf / mm 2 , the proof stress is 27.2 kgf / mm 2 , and the elongation is 23.8.
%, The impact value at room temperature is 2.23kgf-m / cm 2 , the impact value at -40 ℃ is 1.81kgf-m / cm 2 , and the tensile strength and proof stress are
Although lower than FCD40, good elongation and impact values, especially at -40 ° C, are obtained. In addition, the FCD40 with low Si has a high tensile strength and yield strength due to the large amount of pearlite in the microstructure, but the elongation and the impact value are significantly low. Ordinary Si% with Bi added
In the FCD, graphite has a fine structure and a large amount of ferrite in the microscopic structure. However, compared with the material of the present invention having low Si, the FCD has elongation and a low impact resistance. In particular, no remarkable improvement in the low temperature impact value at -40 ° C was observed. As described above, it is understood that the material of the present invention is an extremely superior material as compared with the conventional material or the material obtained by reducing the Si content or adding Bi. It is also understood that excellent materials can be obtained without heat treatment. [Effects of the Invention] As is clear from the above description, the spheroidal graphite cast iron of the present invention has a low Si value, and by adding a trace amount of Bi, heat treatment is performed without or with heat treatment. As a result, by heat treatment at low temperature for a short time, the number of graphite particles increases, the ferrite ratio improves, pearlite decreases, sufficient elongation and impact value can be secured, and the adverse effect of silico-ferrite, that is, hardness It is possible to reduce the rise in temperature, the decrease in elongation, the decrease in the impact value, especially the decrease in the impact value at an extremely low temperature of about -40 ° C. Also, as mentioned above, it has excellent tensile strength, elongation and impact value in the as-cast state, but when heat-treated, it has more excellent elongation, impact value, especially impact value at low temperature compared to the as-cast material. Is improved. That is, it has a remarkable effect in improving the mechanical properties of spheroidal graphite cast iron and reducing the manufacturing cost.
【図面の簡単な説明】
第１図（ａ），（ｂ），（ｃ），（ｄ）は金属顕微鏡組
織写真、第2,3図はともに機械的性質を示すものであ
る。BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a), (b), (c), and (d) are metallographic micrographs, and FIGS. 2 and 3 show mechanical properties.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 酒井 潤 埼玉県和光市中央１丁目４番１号 株式 会社本田技術研究所内 (72)発明者 夏目 毅 埼玉県和光市中央１丁目４番１号 株式 会社本田技術研究所内 (56)参考文献 特開 昭58−45311（ＪＰ，Ａ) ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Jun Sakai 1-4-1 Chuo, Wako-shi, Saitama Inside Honda Technical Research Institute (72) Inventor Takeshi Natsume 1-4-1 Chuo, Wako-shi, Saitama Inside Honda Technical Research Institute (56) Reference JP-A-58-45311 (JP, A)
Claims (1)
湯に0.005〜0.03％のBiを添加し、該Bi添加と同時に又
は添加後に接種を行ない、黒鉛粒数を300ケ/mm2以上、
かつ−40℃における衝撃値が1.5kgf−m/cm2−以上とし
た球状黒鉛鋳鉄。 ２．Biの含有量を0.0015〜0.0150％とした特許請求の範
囲第１項記載の球状黒鉛鋳鉄。(57) [Claims] % By weight C: 3.0 to 4.0% Si: 1.5 to less than 2.0% Mn: <0.3% P: <0.03% Cr: <0.10% Mg: 0.02 to 0.06% CE value (carbon equivalent = C + 1/3 x (Si + P) ): 3.9 to 4.6% Bi consisting of residual iron and unavoidable impurities and having the above composition was added 0.005 to 0.03% Bi, and inoculation was carried out simultaneously with or after the addition of Bi, and the number of graphite particles was 300 / mm 2 or more,
And the spheroidal graphite cast iron has an impact value at -40 ° C of 1.5 kgf-m / cm 2 or more. 2. The spheroidal graphite cast iron according to claim 1, wherein the Bi content is 0.0015 to 0.0150%.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62323813A JP2677367B2 (en) | 1987-03-09 | 1987-12-23 | Spheroidal graphite cast iron |
| DE3807455A DE3807455C2 (en) | 1987-03-09 | 1988-03-08 | Nodular cast iron with high impact strength and method for its treatment |
| GB8805483A GB2203448B (en) | 1987-03-09 | 1988-03-08 | Nodular cast iron |
| US07/165,873 US4889687A (en) | 1987-03-09 | 1988-03-09 | Nodular cast iron having a high impact strength and process of treating the same |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5220687 | 1987-03-09 | ||
| JP62-52206 | 1987-03-09 | ||
| JP62323813A JP2677367B2 (en) | 1987-03-09 | 1987-12-23 | Spheroidal graphite cast iron |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JPS64246A JPS64246A (en) | 1989-01-05 |
| JPH01246A JPH01246A (en) | 1989-01-05 |
| JP2677367B2 true JP2677367B2 (en) | 1997-11-17 |
Family
ID=26392818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62323813A Expired - Lifetime JP2677367B2 (en) | 1987-03-09 | 1987-12-23 | Spheroidal graphite cast iron |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2677367B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4658494A (en) * | 1985-05-28 | 1987-04-21 | Hitachi Seiko Ltd. | Apparatus for drilling printed circuit boards |
| JP2730959B2 (en) * | 1988-03-09 | 1998-03-25 | 日立金属株式会社 | Spheroidal graphite cast iron and method for producing the same |
| JPH0270015A (en) * | 1988-09-06 | 1990-03-08 | Hitachi Metals Ltd | Spheroidal graphite cast iron |
| US5346561A (en) * | 1992-02-27 | 1994-09-13 | Hitachi Metals, Ltd. | Spheroidal graphite cast iron member having improved mechanical strength hand method of producing same |
| KR101040658B1 (en) | 2010-11-30 | 2011-06-10 | (주)희원금속 | Spheroidal graphite cast iron for ultra low temperature |
| CN109072364B (en) * | 2016-03-24 | 2021-03-09 | 日立金属株式会社 | Method for preparing nodular cast iron product |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2511044A1 (en) * | 1981-08-04 | 1983-02-11 | Nobel Bozel | FERRO-ALLOY FOR THE TREATMENT OF INOCULATION OF SPHEROIDAL GRAPHITE FONT |
-
1987
- 1987-12-23 JP JP62323813A patent/JP2677367B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS64246A (en) | 1989-01-05 |
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