JP2775049B2 - Manufacturing method of spheroidal graphite cast iron - Google Patents
Manufacturing method of spheroidal graphite cast ironInfo
- Publication number
- JP2775049B2 JP2775049B2 JP59043796A JP4379684A JP2775049B2 JP 2775049 B2 JP2775049 B2 JP 2775049B2 JP 59043796 A JP59043796 A JP 59043796A JP 4379684 A JP4379684 A JP 4379684A JP 2775049 B2 JP2775049 B2 JP 2775049B2
- Authority
- JP
- Japan
- Prior art keywords
- cast iron
- spheroidal graphite
- graphite cast
- less
- temperature
- 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
Description
【発明の詳細な説明】
本発明は、基地組織を安定してベイナイトと残留オー
ステナイト組織となし得る球状黒鉛鋳鉄及びその製造法
に関する。
近年球状黒鉛鋳鉄及びその製造法は長足の進歩を遂
げ、多くの技術が開発されている。特に抗張力100kgf/m
m2以上、伸び10％以上の高強度、高靭性を有する球状黒
鉛鋳鉄が出現するに至り、熱処理技術の進歩は著しいも
のがある。このような高強度、高靭性を有する球状黒鉛
鋳鉄の基地組織は、ベイナイトとオーステナイトの混合
組織であり、このような球状黒鉛鋳鉄及び熱処理法は、
特公昭55−3422号公報あるいは特開昭53−48014号公
報、同53−48015号公報などに記載されている。
ところが、これらの技術は部分的に肉厚の異なる球状
黒鉛鋳鉄製鋳造品、特に50mmを超える肉厚を有する場合
には、そのすべてをパーライトを残留させずに、ベイナ
イトと残留オーステナイト組織とすることはきわめて困
難である。そこで、これの対策のためにMoを添加する技
術を開発し特願昭58−214761号で出願した。Moの添加に
より安定した組織が得られるが第１図に示すように、伸
びが低くなったり、引け性が大きくなる傾向があり、鋳
造品の特性又は形状が限定されることがある。なお第１
図はMo、Ni重量％と伸びとの関係を示すものであり、φ
50mm丸棒からJIS4号引張試験片を切出して伸びを測定し
たものである。
本発明の目的は、球状黒鉛鋳鉄製鋳造品の基地組織を
安定してベイナイトと残留オーステナイト組織となし、
伸びおよび衝撃値が高く、しかも引け性の少ない球状黒
鉛鋳鉄の製造法を提供するにある。
すなわち、本発明の球状黒鉛鋳鉄の製造法は、重量％
で3.0〜4.0％C,1.5〜3.0％Si,0.30〜0.45％Mn,0.06％以
下P,0.02％以下S,0.3〜1.5％Cu,0.7〜3.5％Ni,0.10％以
下Cr,0.02〜0.06％Mg、残部Feおよび不可避的不純物の
組成からなる球状黒鉛鋳鉄を、850〜950℃で0.5〜4.0時
間保持してオーステナイト化し、前記温度からパーライ
ト変態を起こさない冷却速度で急冷して、250〜450℃に
降温し、該温度で1.0〜4.0時間保持した後冷却するダイ
レクトオーステンパ処理を施し、基地組織をベイナイト
と残留オーステナイトの混合組織とし、伸び13％以上で
あること特徴とする。
本発明でC3.0〜4.0％と限定した理由は、Ｃが3.0％未
満では鋳造品の欠陥、特に引け巣が増大するばかりでな
く、セメンタイトが残留して好ましくない。又4.0％を
超えるとキッシュグラファイトが析出して強度が著しく
低下する。
Siは1.5％未満ではセメンタイトが析出し、3.0％を超
えるとキッシュグラファイト助長の原因となったり、靭
性が低下する。
Mnは0.3％未満ではNiの添加量を増大しないと完全な
ベイナイトと残留オーステナイト組織にすることが困難
であるが、このNiは高価であるため経済的に不利益を招
く。Mnが0.5％を超えると炭化物の成長傾向が増大し、
また組織中の偏析が増大するため伸び、衝撃値が低下す
る。
P0.06％を超えるとステダイトの晶出量が多くなり衝
撃値が低下する。
Ｓは0.02％を超えると黒鉛の球状化が阻害される。
Cuは0.3％未満では焼入性が悪く、1.5％を超えてもそ
の効果は変わらないので経済的にも1.5％を上限とする
ことが好ましい。
Niは必要に応じて添加するものであるが、0.7％未満
では肉厚がφ50mmを超えるか、又はそれ以下でも形状が
複雑な鋳物の場合には安定してベイナイトと残留オース
テナイトからなる混合組織が得られず、経済的に不利に
なる。
Crは0.10％を超えるとセメンタイトが析出し易くな
る。
さらにMgは0.02％未満では黒鉛の球状が達成され難
く、0.06％を超えるとセメンタイトガ析出し易くなる。
以上の理由により各種元素の成分範囲を限定したもの
である。
次に熱処理条件について記述する。
まずオーステナイト化する際、850℃より低い温度、
あるいは950℃よりも高い温度ではいずれも伸びが低下
するので850〜950℃と限定したものである。
オーステナイト化の保持時間は、0.5時間未満では完
全にオーステナイト化することが困難であり、4.0時間
を超えるとオーステナイト結晶が粗大化して引張強さが
低下し経済的にも不利である。
また急冷時の保持温度が250℃より低い温度でも伸
び、衝撃値が著しく低下する。450℃より高い温度でも
伸び、衝撃値がやはり低下する。
さらにオーステンパー処理の保持時間が1.0時間未満
では、完全にベイナイト変態が終わらず、4.0時間を超
えるとベイナイト変態が終わった後も保持することにな
り、何等の効果も期待できず経済的に不利益をもたらす
ものである。
実施例（１）
Ni含有量と肉厚が鋳造品の基地組織に及ぼす影響を第
１表に示す。なおテストピースの詳細寸法は第２図に示
す。
実施例（２）
オーステナイト化温度と伸びとの関係を第３図に示
す。図中Ni2.0％の場合を実線で、Mo0.3％の場合を破線
で示す。
実施例（３）
急冷時の保持温度と伸びとの関係を第４図に示す。図
中Ni2.0％の場合を実線で、Mo0.3％の場合を破線で示
す。
実施例（４）
1.化学成分
試料１（本発明材）および試料２（Mo含有の比較材）
の化学成分を第２表に示す。2.熱処理
第５図に示す熱処理を施した。
3.機械的性質
第３表に示すとおりである。
4.組織
試料１（本発明材）および試料２（Mo含有の比較材）
の顕微鏡写真（×400）をそれぞれ第６図と第７図に示
す。
以上の説明で明らかなように、本発明は球状黒鉛鋳鉄
製鋳造品の肉厚の大小にかかわらずベイナイトと残留オ
ーステナイトの混合せる基地組織を安定して得られ、Mo
添加の同一混合組織品より高い伸び、衝撃値と、引け性
の少ない球状黒鉛鋳鉄の製造法であり、工業的にきわめ
て優れた効果を有するものである。Description: TECHNICAL FIELD The present invention relates to a spheroidal graphite cast iron capable of stably forming a base structure into a bainite and a retained austenite structure, and a method for producing the same. In recent years, spheroidal graphite cast iron and its manufacturing method have made great strides, and many technologies have been developed. Especially tensile strength 100kgf / m
m 2 or more, a high strength of at least 10% elongation, leads to spheroidal graphite cast iron having a high toughness appears, advances in heat treatment technology is remarkable. Such a high strength, the base structure of spheroidal graphite cast iron having high toughness is a mixed structure of bainite and austenite, such a spheroidal graphite cast iron and heat treatment method,
It is described in JP-B-55-3422, JP-A-53-48014, and JP-A-53-48015. However, these techniques are based on the spheroidal graphite cast iron castings with partially different wall thicknesses, especially when they have a wall thickness exceeding 50 mm, all of which must have a bainite and residual austenite structure without leaving pearlite. Is extremely difficult. Therefore, a technique for adding Mo was developed as a countermeasure against this, and an application was filed in Japanese Patent Application No. 58-214761. Although a stable structure can be obtained by the addition of Mo, as shown in FIG. 1, the elongation tends to decrease and the shrinkage tends to increase, and the characteristics or shape of the cast product may be limited. The first
The figure shows the relationship between Mo and Ni weight% and elongation.
The elongation was measured by cutting a JIS No. 4 tensile test piece from a 50 mm round bar. An object of the present invention is to stabilize the base structure of a spheroidal graphite cast iron cast product without a bainite and a retained austenite structure,
An object of the present invention is to provide a method for producing spheroidal graphite cast iron having high elongation and impact value and low shrinkage. That is, the method for producing spheroidal graphite cast iron of the present invention is based on
3.0-4.0% C, 1.5-3.0% Si, 0.30-0.45% Mn, 0.06% or less P, 0.02% or less S, 0.3-1.5% Cu, 0.7-3.5% Ni, 0.10% or less Cr, 0.02-0.06% Mg, balance Fe and spheroidal graphite cast iron comprising the composition of unavoidable impurities, austenite by holding at 850 ~ 950 ° C for 0.5 ~ 4.0 hours, quenched from the above temperature at a cooling rate that does not cause pearlite transformation, 250 ~ 450 The temperature is lowered to 0 ° C., the temperature is maintained at the temperature for 1.0 to 4.0 hours, and then the steel is subjected to direct austempering, whereby the base structure is a mixed structure of bainite and residual austenite, and has an elongation of 13% or more. The reason for limiting the C content to 3.0 to 4.0% in the present invention is that if the C content is less than 3.0%, not only the defects in the cast product, especially shrinkage cavities increase, but also cementite remains unpreferably. On the other hand, if it exceeds 4.0%, quiche graphite precipitates and the strength is remarkably reduced. If Si is less than 1.5%, cementite will precipitate, and if it exceeds 3.0%, it will promote Kish graphite or decrease toughness. If the content of Mn is less than 0.3%, it is difficult to form a complete bainite and retained austenite structure unless the amount of Ni added is increased, but this Ni is expensive and causes economical disadvantage. When Mn exceeds 0.5%, the tendency of carbide growth increases,
In addition, the segregation in the structure increases, so that the structure elongates and the impact value decreases. If P exceeds 0.06%, the crystallization amount of steadite increases, and the impact value decreases. If S exceeds 0.02%, spheroidization of graphite is inhibited. If Cu is less than 0.3%, the hardenability is poor, and if it exceeds 1.5%, the effect is not changed. Ni is added as necessary, but if the thickness is less than 0.7%, the wall thickness exceeds φ50mm, or even if it is less than 30%, the mixed structure consisting of bainite and residual austenite is stable in the case of a complicated casting. It is not economical and disadvantageous. If Cr exceeds 0.10%, cementite is likely to precipitate. Further, if Mg is less than 0.02%, it is difficult to achieve graphite spheroids, and if it exceeds 0.06%, cementite gas is easily precipitated. For the above reasons, the component ranges of the various elements are limited. Next, the heat treatment conditions will be described. First, when austenitizing, lower than 850 ° C,
Alternatively, the elongation decreases at a temperature higher than 950 ° C., so that the temperature is limited to 850 to 950 ° C. If the holding time of austenitization is less than 0.5 hour, it is difficult to completely austenite, and if it exceeds 4.0 hours, the austenite crystal becomes coarse and the tensile strength decreases, which is economically disadvantageous. Further, even when the holding temperature during quenching is lower than 250 ° C., elongation occurs, and the impact value is significantly reduced. It stretches even at temperatures higher than 450 ° C, and the impact value also drops. Further, if the holding time of the austempering treatment is less than 1.0 hour, the bainite transformation is not completely completed, and if it exceeds 4.0 hours, it is retained even after the bainite transformation is completed. It brings benefits. Example (1) Table 1 shows the effects of the Ni content and the wall thickness on the matrix structure of the cast product. The detailed dimensions of the test piece are shown in FIG. Example (2) FIG. 3 shows the relationship between the austenitizing temperature and elongation. In the figure, the case of Ni 2.0% is shown by a solid line, and the case of Mo 0.3% is shown by a broken line. Example (3) FIG. 4 shows the relationship between the holding temperature during quenching and the elongation. In the figure, the case of Ni 2.0% is shown by a solid line, and the case of Mo 0.3% is shown by a broken line. Example (4) 1. Chemical components Sample 1 (material of the present invention) and Sample 2 (comparative material containing Mo)
Is shown in Table 2. 2. Heat treatment The heat treatment shown in FIG. 5 was performed. 3. Mechanical properties As shown in Table 3. 4. Microstructure Sample 1 (material of the present invention) and Sample 2 (comparative material containing Mo)
6 and 7 are shown in FIGS. 6 and 7, respectively. As is apparent from the above description, the present invention can stably obtain a matrix structure in which bainite and retained austenite are mixed regardless of the thickness of a cast product made of spheroidal graphite cast iron.
This is a method for producing spheroidal graphite cast iron having higher elongation, impact value, and less shrinkage than the same mixed structure product to which it is added, and has extremely excellent industrial effects.
【図面の簡単な説明】
第１図はMo,Ni重量％と伸びとの関係を示す図、第２図
はテストピースの平面図、第３図はオーステナイト化温
度と伸びとの関係を示す図、第４図は冷却時の保持温度
と伸びとの関係を示す図、第５図は熱処理図、第６、７
図はそれぞれ金属組織を示す顕微鏡写真である。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing the relationship between Mo and Ni weight% and elongation, FIG. 2 is a plan view of a test piece, and FIG. 3 is a diagram showing the relationship between austenitizing temperature and elongation. FIG. 4 is a diagram showing the relationship between the holding temperature and the elongation during cooling, FIG. 5 is a heat treatment diagram, and FIGS.
The figures are micrographs each showing a metal structure.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 石原 安興 福岡県京都郡苅田町長浜町35番地 日立 金属株式会社九州工場内 (72)発明者 大塚 公輝 福岡県京都郡苅田町長浜町35番地 日立 金属株式会社九州工場内 (56)参考文献 特開 昭58−185745（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) C22C 37/08──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Yasuko Ishihara, 35, Nagahama-cho, Kanda-cho, Kyoto-gun, Fukuoka Prefecture Inside the Kyushu Plant of Hitachi Metals Co., Ltd. (56) References JP-A-58-185745 (JP, A) (58) Fields investigated (Int. Cl. 6 , DB name) C22C 37/08
Claims (1)
n,0.06％以下P,0.02％以下S,0.3〜1.5％Cu,0.7〜3.5％N
i,0.10％以下Cr,0.02〜0.06％Mg、残部Feおよび不可避
的不純物の組成からなる球状黒鉛鋳鉄を、850〜950℃で
0.5〜4.0時間保持してオーステナイト化し、前記温度か
らパーライト変態を起こさない冷却速度で急冷して、25
0〜450℃に降温し、該温度で1.0〜4.0時間保持した後冷
却するダイレクトオーステンパ処理を施し、基地組織を
ベイナイトと残留オーステナイトの混合組織とし、伸び
13％以上であること特徴とする球状黒鉛鋳鉄の製造法。(57) [Claims] 3.0-4.0% C, 1.5-3.0% Si, 0.30-0.45% M by weight%
n, 0.06% or less P, 0.02% or less S, 0.3 to 1.5% Cu, 0.7 to 3.5% N
i, 0.10% or less Cr, 0.02-0.06% Mg, spheroidal graphite cast iron consisting of the balance of Fe and unavoidable impurities at 850-950 ° C
Austenite by holding for 0.5 to 4.0 hours, quenching from the above temperature at a cooling rate that does not cause pearlite transformation, 25
The temperature was lowered to 0 to 450 ° C., the temperature was maintained at the temperature for 1.0 to 4.0 hours, and then a direct austempering treatment was performed to cool the base material to a mixed structure of bainite and residual austenite.
A method for producing spheroidal graphite cast iron, characterized by being at least 13%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59043796A JP2775049B2 (en) | 1984-03-09 | 1984-03-09 | Manufacturing method of spheroidal graphite cast iron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59043796A JP2775049B2 (en) | 1984-03-09 | 1984-03-09 | Manufacturing method of spheroidal graphite cast iron |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60190549A JPS60190549A (en) | 1985-09-28 |
| JP2775049B2 true JP2775049B2 (en) | 1998-07-09 |
Family
ID=12673705
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59043796A Expired - Lifetime JP2775049B2 (en) | 1984-03-09 | 1984-03-09 | Manufacturing method of spheroidal graphite cast iron |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2775049B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS616249A (en) * | 1984-06-20 | 1986-01-11 | Toyota Motor Corp | High strength spheroidal graphite cast iron with superior machinability |
| JPS63192821A (en) * | 1987-02-05 | 1988-08-10 | Railway Technical Res Inst | Production of brake disk material for vehicle |
| CN103789604B (en) * | 2014-01-26 | 2016-06-01 | 苏州雷姆斯汽车工程有限公司 | A kind of nodular cast iron alloy and the application in thin wall type hydrodynamic retarding device impeller thereof |
| CN105018833A (en) * | 2015-07-09 | 2015-11-04 | 王波林 | Isothermal quenching ductile cast iron and method for producing end of propelling rod through isothermal quenching ductile cast iron |
| CN116574874A (en) * | 2023-04-15 | 2023-08-11 | 盐城震业机械股份有限公司 | Preparation method of austempered ductile iron |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58185745A (en) * | 1982-04-22 | 1983-10-29 | Mazda Motor Corp | Spherical graphite cast iron parts and their manufacture |
-
1984
- 1984-03-09 JP JP59043796A patent/JP2775049B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60190549A (en) | 1985-09-28 |
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