JP2538905B2 - Steel material for centrifugal casting molds with excellent high temperature strength and toughness - Google Patents
Steel material for centrifugal casting molds with excellent high temperature strength and toughnessInfo
- Publication number
- JP2538905B2 JP2538905B2 JP62050385A JP5038587A JP2538905B2 JP 2538905 B2 JP2538905 B2 JP 2538905B2 JP 62050385 A JP62050385 A JP 62050385A JP 5038587 A JP5038587 A JP 5038587A JP 2538905 B2 JP2538905 B2 JP 2538905B2
- Authority
- JP
- Japan
- Prior art keywords
- toughness
- less
- strength
- high temperature
- centrifugal casting
- 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 - Fee Related
Links
Description
【発明の詳細な説明】 （産業上の利用分野） この発明は、高温強度・靭性に優れた遠心鋳造金型用
鋼材に関し、とくに製鉄用ロールや鋳造管、各種スリー
ブなどの遠心鋳造の際に使用される金型の寿命の延長を
図ろうとするものである。TECHNICAL FIELD The present invention relates to a steel material for a centrifugal casting mold which is excellent in high-temperature strength and toughness, and is particularly useful for centrifugal casting of iron-making rolls, casting pipes, various sleeves and the like. It is intended to extend the life of the mold used.
（従来の技術） 遠心鋳造金型用鋼材としては、従来、主としてSF45や
SF50などの安価な炭素鋼が用いられてきた。(Prior Art) Conventionally, as steel materials for centrifugal casting molds, mainly SF45 and
Inexpensive carbon steels such as SF50 have been used.
ところでかかる遠心鋳造金型は、その内面は直接ある
いはパウダーを介して間接的に溶湯と接して加熱され、
一方外面は強度保持の目的から水冷または水スプレーな
どによって冷却されているケースが多いが、製品の鋳造
サイクル毎に、このような加熱と冷却とが繰り返される
と、上記の如き炭素鋼は高温強度や低温靭性が小さいこ
ともあって、金型の内面には亀甲状の割れが生じる。By the way, the centrifugal casting mold is heated by contacting the inner surface with the molten metal directly or indirectly through the powder,
On the other hand, the outer surface is often cooled by water cooling or water spray for the purpose of maintaining strength, but when such heating and cooling are repeated in each casting cycle of the product, the carbon steel as described above has high temperature strength. Since the low temperature toughness is low, a hexagonal crack occurs on the inner surface of the mold.
従来、使用中に生じたきずやクラックなどは溶接補修
して何回も使用されてきたが、かような補修は煩雑なば
かりでなく、生産性の低下を招く不利があった。Conventionally, flaws and cracks generated during use have been repaired by welding and used many times. However, such repair is not only complicated but there is a disadvantage that productivity is lowered.
（発明が解決しようとする問題点） JIS規格で規定されている炭素鋼鍛鋼品は、JIS G 320
1にてSF35〜SF65が記載され、C:0.60wt％（以下単に％
で示す（以下、Si:0.15〜0.50％,Mn:0.30〜1.20％,P:0.
03％以下、S:0.035％以下と規定されている。しかしな
がらこの鋼種は、高温強度あるいは低温靭性が不十分で
あり、かつ、溶接性が考慮されていないなどの問題点が
ある。(Problems to be solved by the invention) Forged carbon steel products stipulated by JIS standard are JIS G 320
SF35 to SF65 are described in 1, C: 0.60 wt% (hereinafter simply referred to as%
(Si: 0.15 to 0.50%, Mn: 0.30 to 1.20%, P: 0.
It is specified to be 03% or less and S: 0.035% or less. However, this type of steel has problems that the high temperature strength or the low temperature toughness is insufficient and the weldability is not taken into consideration.
一方、圧力容器用炭素鋼鍛鋼品としては、JIS G 3202
にてSFVC 2Bが記載され、C:0.30％以下、Si:0.35％以
下、Mn:0.70〜1.35％,P:0.030％,S:0.030％以下、Ni:0.
40％以下、Cr:0.25％以下、Mo:0.10％以下、V:0.05％以
下と規定されている。この鋼種は、溶接性や低温靭性の
点については上掲のJIS G 3201よりもかなり改善されて
いるけれども、高温強度が低いというところに問題を残
していた。On the other hand, as carbon steel forgings for pressure vessels, JIS G 3202
SFVC 2B is described in C: 0.30% or less, Si: 0.35% or less, Mn: 0.70 to 1.35%, P: 0.030%, S: 0.030% or less, Ni: 0.
It is specified that 40% or less, Cr: 0.25% or less, Mo: 0.10% or less, V: 0.05% or less. Although this steel grade is considerably improved in terms of weldability and low temperature toughness compared to JIS G 3201 described above, it still has a problem in that it has low high temperature strength.
（問題点を解決するための手段） 遠心鋳造金型は使用中に生じたきず、クラックなどを
溶接補修して何回も使用され、鋼剤としては主として安
価な炭素鋼が使用されてきたのは前述したとおりであ
る。(Means for solving problems) Centrifugal casting dies have been used many times by welding and repairing flaws and cracks that occurred during use, and carbon steel has been mainly used as a steel agent. Is as described above.
この寿命を長くするためには、高温強度・低温靭性を
改善することが重要である。一般に、炭素鋼の機械的性
質は化学成分と、熱処理によって支配される。通常、遠
心鋳造金型用鋼剤の熱処理は焼ならし−焼もどしが施さ
れるので、当材の機械的性質は、化学成分で概ね決定さ
れる。ここに強度は炭素当量（Ceq＝Ｃ＋Si/24＋Mn/6＋
Ni/40＋Cr/5＋Mo/4＋V/14）の増加により向上でき、Ceq
の増加はＣ量を増やすことで容易に達成できるが、これ
は靭性面からの制約を受ける。他方、靭性向上にはMn/C
の増加が有効である。In order to extend this life, it is important to improve high temperature strength and low temperature toughness. Generally, the mechanical properties of carbon steel are governed by the chemical composition and heat treatment. Normally, the heat treatment of the steel material for centrifugal casting molds is performed by normalizing-tempering, so the mechanical properties of this material are generally determined by the chemical composition. Here, the strength is the carbon equivalent (Ceq = C + Si / 24 + Mn / 6 +
Ceq can be improved by increasing Ni / 40 + Cr / 5 + Mo / 4 + V / 14)
Can be easily achieved by increasing the amount of C, but this is restricted by the toughness. On the other hand, for improving toughness, Mn / C
Is effective.
この発明では、Moを添加して、靭性を劣化させること
なしに高温強度（400℃以上での引張強さ）を向上さ
せ、さらに、細粒化元素としてNb,Ti,Alの１種あるいは
２種以上を添加することにより強度と靭性との一層の向
上を達成した。In this invention, Mo is added to improve the high temperature strength (tensile strength at 400 ° C. or higher) without deteriorating the toughness, and one of Nb, Ti and Al or 2 as a grain refining element. By adding more than one species, the strength and toughness were further improved.
すなわちこの発明は、 C :0.10〜0.30％ Si:0.15〜0.50％ Mn:1.00〜2.00％ Mo:0.20〜0.40％ Cu:0.25％以下 Ni:0.40％以下 Cr:0.40％以下および V :0.40％以下 を含み、かつ Nb,TiおよびAlのうちから選んだ一種または二種以上:0.
01〜0.10％を含有し、残部は不可避的不純物およびFeの
組成になり、下記式で定義されるCeqが0.500〜0.510の
範囲を満足することを特徴とする高温強度・靭性に優れ
た遠心鋳造金型用鋼材である。That is, the present invention is C: 0.10 to 0.30% Si: 0.15 to 0.50% Mn: 1.00 to 2.00% Mo: 0.20 to 0.40% Cu: 0.25% or less Ni: 0.40% or less Cr: 0.40% or less and V: 0.40% or less And one or more selected from Nb, Ti and Al: 0.
Centrifugal casting with excellent high temperature strength and toughness characterized by containing 01 to 0.10%, the balance being inevitable impurities and Fe composition, and Ceq defined by the following formula satisfying the range of 0.500 to 0.510 It is a steel material for molds.
記 Ceq＝Ｃ＋Si/24＋Mn/6＋Ni/40＋Cr/5＋Mo/4＋V/14 （作用） この発明の遠心鋳造金型用鋼材において、化学組成
を、上記の通りに規制した理由について説明する。Description Ceq = C + Si / 24 + Mn / 6 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 (Function) In the steel material for centrifugal casting mold of the present invention, the reason why the chemical composition is regulated as described above will be explained.
（ａ） C:0.10〜0.30％ 靭性を改善するためにはＣ量を減少させることが望ま
しいが、Ｃ量を0.10％未満にすると他の成分との兼合い
から強度が不足してくる。一方、Ｃ量が0.3％を超える
と優れた靭性が得られない。(A) C: 0.10 to 0.30% It is desirable to reduce the C content in order to improve the toughness, but if the C content is less than 0.10%, the strength becomes insufficient due to the balance with other components. On the other hand, if the C content exceeds 0.3%, excellent toughness cannot be obtained.
（ｂ） Si:0.15〜0.50％ 製鋼時の脱酸、および強度の維持を考えて0.15〜0.50
％とした。(B) Si: 0.15 to 0.50% 0.15 to 0.50 in consideration of deoxidation during steelmaking and maintenance of strength
%.
（ｃ） Mn:1.00〜2.00％ 強度と靭性をともに改善し、かつ安価な成分として、
Mn量を増加させることが望ましいが、Mn量が2.00％を超
えると逆に靭性を劣化させる。一方、Mn量が1.00％に満
たないと他の成分との兼合いから強度が不足してくる。
とくにMn/Cが小さいと靭性の改善が期待できないので、
Mn/Cは6.0以上とするのが望ましい。(C) Mn: 1.00 to 2.00% As an inexpensive component that improves both strength and toughness,
It is desirable to increase the amount of Mn, but if the amount of Mn exceeds 2.00%, the toughness deteriorates. On the other hand, if the Mn content is less than 1.00%, the strength becomes insufficient due to the balance with other components.
Especially when Mn / C is small, improvement in toughness cannot be expected, so
It is desirable that Mn / C be 6.0 or more.
（ｄ） Mo:0.20〜0.40％ 靭性を劣化させずに高温強度（400℃以上での引張強
さ）を向上させるのに寄与するが、0.20％未満ではその
添加効果に乏しく、一方、0.40％を超えると靭性劣化の
不利が生じる。(D) Mo: 0.20 to 0.40% Contributes to improving high temperature strength (tensile strength at 400 ° C or higher) without deteriorating toughness, but if it is less than 0.20%, its addition effect is poor, while 0.40% If it exceeds, the disadvantage of deterioration of toughness occurs.
（ｅ） Cu,Ni,Cr,V これらの成分はいずれも、鋼材の強度を向上させるの
に有効に寄与するが、あまりに多量に含有されると溶接
性、炭素鋼の不純物規制などの点で好ましくないので、
それぞれCu:0.25％以下、Ni:0.40％以下、Cr:0.40％以
下、V:0.40％以下の範囲で添加することとした。(E) Cu, Ni, Cr, V Any of these components effectively contributes to improving the strength of the steel material, but if it is contained in too much amount, in terms of weldability and carbon steel impurity regulation, etc. Because it is not preferable,
Cu: 0.25% or less, Ni: 0.40% or less, Cr: 0.40% or less, V: 0.40% or less, respectively.
（ｆ） Nb,Ti,Al これらの成分はいずれも、鋼材の結晶粒を細粒化させ
て、強度と靭性をともに改善するのに有用な元素である
が、含有量があまりに少ないとその添加効果に乏しく、
一方あまりに多いと巨大析出物、介在物が生成するなど
の不利があるので、単独使用および併用いずれの場合に
おいても0.01〜0.10％の範囲で添加するものとした。(F) Nb, Ti, Al Each of these components is an element useful for refining the crystal grains of the steel material and improving both strength and toughness, but if the content is too small, its addition Poorly effective,
On the other hand, if it is too much, there is a disadvantage such as formation of huge precipitates and inclusions. Therefore, it was added in the range of 0.01 to 0.10% in both cases of single use and combined use.
この発明では、Moの添加によって、靭性の低下を招く
ことなしに高温強度を効果的に向上させるのであるが、
その前提として、遠心鋳造金型用鋼材として基本的な強
度は予め確保しておく必要があり、この基本強度は低す
ぎてもまた高すぎても好くない。In the present invention, the addition of Mo effectively improves the high temperature strength without lowering the toughness,
As a premise, it is necessary to secure a basic strength in advance as a steel material for centrifugal casting molds, and it is not preferable that the basic strength is too low or too high.
そこで、この発明では、かかる強度の確保を、次式で
定義される炭素当量（Ceq）によって規定するものとし
た。Therefore, in the present invention, ensuring of such strength is defined by the carbon equivalent (Ceq) defined by the following equation.
Ceq＝Ｃ＋Si/24＋Mn/6＋Ni/40＋Cr/5＋Mo/4＋V/14 ここに、適切な基本強度を得るには、後述する実施例
にも示したとおり、上掲式で示されるCeqが0.500〜0.51
0の範囲を満足する必要があるので、この発明ではCeqに
つき、0.500〜0.510の範囲に限定した。Ceq = C + Si / 24 + Mn / 6 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 Here, in order to obtain an appropriate basic strength, Ceq represented by the above formula is 0.500 to 0.51 as shown in Examples described later.
Since it is necessary to satisfy the range of 0, in the present invention, Ceq is limited to the range of 0.500 to 0.510.
（実施例） 表１に示す種々の成分組成になる鋼を、溶解−造塊−
鍛造後、870℃,8時間（ｈ）の焼ならし−620℃,12時間
（ｈ）の焼もどしからなる熱処理を施し、厚み300mmの
供試鋼を製造した。(Example) Steels having various compositional compositions shown in Table 1 were melted-ingot-formed.
After forging, a heat treatment consisting of normalizing at 870 ° C. for 8 hours (h) and tempering at −620 ° C. for 12 hours (h) was performed to manufacture a test steel having a thickness of 300 mm.
かくして得られた各供試鋼の組織および機械的性質に
ついて調べた結果を表２に、また各温度における引張り
特性およびシャルピー衝撃遷移曲線についての調査結果
を第１図および第２図にそれぞれ示す。The results of examining the structure and mechanical properties of the thus-obtained test steels are shown in Table 2, and the results of examining the tensile properties and Charpy impact transition curves at each temperature are shown in FIGS. 1 and 2, respectively.
供試鋼の組織はいずれも、フェライト＋パーライト組
織を呈していたが、フェライト粒径はAl＋NbまたはAl＋
Tiを含有する鋼の方がAlのみを含有する鋼よりも細粒化
していた。 The microstructures of the test steels were all ferrite + pearlite, but the ferrite grain size was Al + Nb or Al +
The steel containing Ti was finer-grained than the steel containing only Al.
さて比較鋼１は通常のSF 50であるが、Mn/Cが小さい
ため靭性に劣っていた。比較鋼２は比較鋼１よりもMn/C
を大きくして靭性を改善した例、また比較鋼３は比較鋼
１よりも炭素当量（Ceq）およびMn/Cを大きくして強度
と靭性とを改善した例である。しかしながら、かような
処理を施してもなお比較鋼2,3は、比較鋼１と同様、試
験温度が400℃を超えると強度の急激な低下を免れ得な
かった。Comparative Steel 1 had a normal SF 50, but had a low Mn / C and was poor in toughness. Comparative Steel 2 is more Mn / C than Comparative Steel 1
Is an example of improving the toughness, and Comparative Steel 3 is an example of improving the strength and toughness by increasing the carbon equivalent (Ceq) and Mn / C as compared with Comparative Steel 1. However, even if such a treatment was performed, Comparative Steels 2 and 3 were inevitably abruptly reduced in strength when the test temperature exceeded 400 ° C., as in Comparative Steel 1.
これに対し発明鋼４〜６はいずれも、比較鋼１よりも
高温強度（400℃以上での引張り強さ）が大幅に（400℃
でΔTS＝7.5kgf/mm2,500℃でΔTS＝16kgf/mm2）改善さ
れていて、とくにMn/Cの確保はもとよりAl＋NbまたはAl
＋Tiを添加して結晶粒の細粒化を図った発明鋼5,6は靭
性の改善も併せて達成されている。On the other hand, the invention steels 4 to 6 all have significantly higher high-temperature strength (tensile strength at 400 ° C or higher) than the comparative steel 1 (400 ° C).
In ΔTS = 7.5kgf / mm 2, 500 ℃ in ΔTS = 16kgf / mm 2) have been improved, as well the securing of particular Mn / C Al + Nb or Al
The invention steels 5 and 6 in which + Ti is added to make the crystal grains finer have also achieved improvement in toughness.
（発明の効果） かくしてこの発明によれば、高温強度は勿論のこと低
温靭性に優れた遠心鋳造金型用鋼材を容易に得ることが
でき、その寿命延長ひいては生産性の向上に偉効を奏す
る。(Effects of the Invention) Thus, according to the present invention, it is possible to easily obtain a steel material for centrifugal casting molds which is excellent not only in high-temperature strength but also in low-temperature toughness, and has a great effect in extending the life thereof and, in turn, improving productivity. .
【図面の簡単な説明】 第１図は、種々の試験温度における引張り特性を示した
グラフ、 第２図は、シャルピー衝撃遷移曲線を示したグラフであ
る。BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a graph showing tensile properties at various test temperatures, and FIG. 2 is a graph showing Charpy impact transition curves.
Claims (1)
01〜0.10wt％ を含有し、残部は不可避的不純物およびFeの組成にな
り、下記式で定義されるCeqが0.500〜0.510の範囲を満
足することを特徴とする高温強度・靭性に優れた遠心鋳
造金型用鋼材。 記 Ceq＝Ｃ＋Si/24＋Mn/6＋Ni/40＋Cr/5＋Mo/4＋V/141. C: 0.10 to 0.30 wt% Si: 0.15 to 0.50 wt% Mn: 1.00 to 2.00 wt% Mo: 0.20 to 0.40 wt% Cu: 0.25 wt% or less Ni: 0.40 wt% or less Cr: 0.40 wt% Or less and V: 0.40 wt% or less, and one or more selected from Nb, Ti and Al: 0.
Centrifugal with excellent high temperature strength and toughness, characterized by containing 01 to 0.10 wt%, the balance being inevitable impurities and Fe composition, and Ceq defined by the following formula satisfying the range of 0.500 to 0.510. Steel material for casting molds. Note Ceq = C + Si / 24 + Mn / 6 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62050385A JP2538905B2 (en) | 1987-03-06 | 1987-03-06 | Steel material for centrifugal casting molds with excellent high temperature strength and toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62050385A JP2538905B2 (en) | 1987-03-06 | 1987-03-06 | Steel material for centrifugal casting molds with excellent high temperature strength and toughness |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63219552A JPS63219552A (en) | 1988-09-13 |
| JP2538905B2 true JP2538905B2 (en) | 1996-10-02 |
Family
ID=12857400
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62050385A Expired - Fee Related JP2538905B2 (en) | 1987-03-06 | 1987-03-06 | Steel material for centrifugal casting molds with excellent high temperature strength and toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2538905B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6328547B2 (en) * | 2014-12-22 | 2018-05-23 | 株式会社神戸製鋼所 | Manufacturing method of large cast steel product and large cast steel product |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54110914A (en) * | 1978-02-20 | 1979-08-30 | Sumitomo Metal Ind Ltd | High strength and high toughness steel |
| JPS5891151A (en) * | 1981-11-27 | 1983-05-31 | Kawasaki Steel Corp | Steel for high-temperature and high-pressure apparatus |
-
1987
- 1987-03-06 JP JP62050385A patent/JP2538905B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS54110914A (en) * | 1978-02-20 | 1979-08-30 | Sumitomo Metal Ind Ltd | High strength and high toughness steel |
| JPS5891151A (en) * | 1981-11-27 | 1983-05-31 | Kawasaki Steel Corp | Steel for high-temperature and high-pressure apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63219552A (en) | 1988-09-13 |
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