JP2834196B2 - High strength, high toughness ferritic heat resistant steel - Google Patents
High strength, high toughness ferritic heat resistant steelInfo
- Publication number
- JP2834196B2 JP2834196B2 JP18363889A JP18363889A JP2834196B2 JP 2834196 B2 JP2834196 B2 JP 2834196B2 JP 18363889 A JP18363889 A JP 18363889A JP 18363889 A JP18363889 A JP 18363889A JP 2834196 B2 JP2834196 B2 JP 2834196B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- resistant steel
- ferritic heat
- heat resistant
- strength
- 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
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は高い靭性を有する高強度耐熱鋼に関するもの
であり、特に高温におけるクリープ強度が極めて優秀な
フェライト系耐熱鋼に係わるものである。Description: TECHNICAL FIELD The present invention relates to a high-strength heat-resistant steel having high toughness, and particularly to a ferritic heat-resistant steel having extremely excellent creep strength at high temperatures.
高温高効率型のエネルギープラント用鋼材として、ク
リープ強度が極めて優秀で且つオーステナイト系ステン
レス鋼に見られるような応力腐食割れの心配が少ないフ
ェライト系耐熱鋼が強く要望されている。As a high-temperature and high-efficiency steel material for an energy plant, a ferritic heat-resistant steel having extremely excellent creep strength and having less fear of stress corrosion cracking as seen in austenitic stainless steel is strongly demanded.
この種の用途を目的として開発された鋼としては9〜
12%のCrを含有して耐蝕性を向上させ且つWの固溶体強
化を利用してクリープ強度を向上させた鋼種(文献、伊
勢田ら:CAMP−ISIJ VOL.2(1989)−772)がある。Steel developed for this type of application is 9-
There is a steel type containing 12% Cr to improve the corrosion resistance and improve the creep strength by utilizing the solid solution strengthening of W (Literature, ISETA et al .: CAMP-ISIJ VOL.2 (1989) -772).
しかしながら従来鋼種では、Wの添加制御が適切でな
いため、マルテンサイト相中にδフェライトを析出し靭
性を著しく低下させるという重大な欠点を有する。δフ
ェライトは母相マルテンサイトより著しく柔らかい相で
ありこのような柔らかい第二相が硬い母相中に分散する
場合、鋼全体の衝撃特性は著しく低下する。However, conventional steels have a serious drawback in that δ ferrite precipitates in the martensite phase and the toughness is remarkably reduced because the addition control of W is not appropriate. δ ferrite is a significantly softer phase than the parent martensite, and if such a soft second phase is dispersed in a hard parent phase, the impact properties of the entire steel are significantly reduced.
本発明はこのような事情に鑑み創案されたもので、W
を含む高Cr系鋼に、オーステナイト安定化元素であるCo
を適切なバランスで添加してδフェライトの析出を抑制
し且つ高いクリープ強度を持たせることに成功したもの
である。The present invention has been made in view of such circumstances, and W
Co, which is an austenite stabilizing element, is added to high Cr steels containing
Was added in an appropriate balance to suppress the precipitation of δ ferrite and achieve high creep strength.
本発明の特徴とするところは、重量比でC:0.03〜0.2
%、Si:0.05〜1%、Mn:0.1〜1.5%、Cr:8〜13%、Ni:
0.01〜1%、Mo:0.5〜1.5%、V:0.05〜0.5%、Nb:0.01
〜0.15%、N:0.002〜0.1%、W:1%以上、Co:1.5%以上
を含有して且つ1≧1.5W−Co≧0なる関係を満足し、残
部Fe及び不可避的不純物からなる成分系を有することに
ある。The feature of the present invention is that the weight ratio C: 0.03 to 0.2.
%, Si: 0.05-1%, Mn: 0.1-1.5%, Cr: 8-13%, Ni:
0.01-1%, Mo: 0.5-1.5%, V: 0.05-0.5%, Nb: 0.01
0.15%, N: 0.002 to 0.1%, W: 1% or more, Co: 1.5% or more, and satisfies the relationship of 1 ≧ 1.5W−Co ≧ 0, with the balance being Fe and unavoidable impurities. To have a system.
以下本発明の限定理由を説明する。 Hereinafter, the reasons for limitation of the present invention will be described.
まずCは、焼入れ性と強度確保のため0.03%以上必要
であるが、0.2%を越えた場合の溶接性の低下が著し
い。このためC量は0.03〜0.2%とする。First, C is required to be 0.03% or more in order to secure hardenability and strength, but when it exceeds 0.2%, the weldability is significantly reduced. Therefore, the C content is set to 0.03 to 0.2%.
Siは脱酸材として重要であり最低0.05%を必要とす
る。しかし、靭性及び溶接性に対して悪影響を与えるも
のであり、1%以上添加した場合靭性及び溶接性を損な
う。したがってSi量は0.05〜1%とする。Si is important as a deoxidizer and requires at least 0.05%. However, it has an adverse effect on toughness and weldability, and if added 1% or more, toughness and weldability are impaired. Therefore, the amount of Si is set to 0.05 to 1%.
Mnは脱酸及び焼入れ性確保のため重要であるため最低
0.1%を確保する必要があるが、1.5%を越えると溶接性
の点から好ましくない。このためMn量は0.1〜1.5%とす
る。Mn is important because it is important for deoxidation and hardenability.
It is necessary to secure 0.1%, but if it exceeds 1.5%, it is not preferable from the viewpoint of weldability. Therefore, the Mn content is set to 0.1 to 1.5%.
Crは耐蝕性と焼入れ性を確保する上で非常に重要であ
るため最低8%必要であるが、13%を越えると溶接性を
著しく損なうと同時にδフェライトを析出させるため靭
性確保上好ましくない。したがってCr量は8〜13%とす
る。Since Cr is very important for ensuring corrosion resistance and hardenability, at least 8% is necessary. However, if it exceeds 13%, weldability is remarkably impaired and δ ferrite is precipitated, which is not preferable for securing toughness. Therefore, the Cr content is set to 8 to 13%.
Niはδフェライトの生成を抑制することから0.01%以
上が添加される。しかし1%を越えるとクリープ強度を
著しく低下させるため上限は1%とし、下限を0.01%と
する。Ni is added in an amount of 0.01% or more because it suppresses the formation of δ ferrite. However, if it exceeds 1%, the creep strength is significantly reduced, so the upper limit is set to 1% and the lower limit is set to 0.01%.
Moは基地中に固溶した場合においてもまた炭化物とし
て析出した場合においても著しいクリープ抵抗となるた
め最低0.5%必要であるが、1.5%を越えると溶接性を損
ない且つδフェライトを析出させるため靭性の低下をも
招く。したがってMo量は0.5〜1.5%とする。Mo has a minimum creep resistance of 0.5% if it forms a solid solution in the matrix or precipitates as carbides. However, if it exceeds 1.5%, the weldability is impaired and δ ferrite is precipitated because δ ferrite is precipitated. Also leads to a decrease. Therefore, the amount of Mo is set to 0.5 to 1.5%.
Vは炭窒化物として析出させて強度を確保する上で重
要であるため最低0.05%が必要であるが、0.5%を越え
る添加は溶接性を著しく損なう。したがってV量は0.05
〜0.5%とする。V is important for securing strength by precipitating it as carbonitride, so at least 0.05% is required. However, addition exceeding 0.5% significantly impairs weldability. Therefore, the amount of V is 0.05
To 0.5%.
NbはV同様炭窒化物として析出して強度を確保するほ
か、結晶粒を微細化して靭性を与える元素としても重要
であるため最低0.01%が必要であるが、0.15%を越える
とその効果は飽和してしまうだけではなく溶接性の低下
も招く。したがってNb量は0.01〜0.15%とする。Nb precipitates as carbonitride like V to secure strength and is also important as an element that refines crystal grains and imparts toughness, so at least 0.01% is required. Not only saturation occurs, but also weldability decreases. Therefore, the Nb content is set to 0.01 to 0.15%.
Nは基地中に固溶しても、また、窒化物として析出し
ても著しいクリープ抵抗として寄与するため最低0.002
%を必要とする。しかし、0.1%以上を添加した場合溶
接性と靭性を同時に損なうようになる。したがってN量
は0.002〜0.1%とする。N contributes as a remarkable creep resistance even if it forms a solid solution in the matrix or precipitates as a nitride.
Need%. However, when 0.1% or more is added, weldability and toughness are impaired at the same time. Therefore, the N content is set to 0.002 to 0.1%.
Wはフェライト系鋼のクリープ強度に寄与する固溶体
強化元素として最も優れた元素である。またAC1点を上
昇させるので、組織安定化を目的とした高温焼もどしを
可能にする。Wは最低1%の添加を必要とする。しかし
過剰の添加によりδフェライトを析出させ著しい靭性低
下を招くという重大な弊害を引き起こす。一方Coは、W
添加によって生じるδフェライトの析出という問題点を
相殺する重要な元素であり、最低1.5%以上を必要とす
る。しかし過剰添加するとAC1点を下げるため、高温焼
もどしが不可能となり組織の安定化処理ができなくなる
という欠点を有する。このようにWとCoは互いに相反す
る効果を与える元素であり、本合金系での適切な添加バ
ランスは1≧1.5W−Co≧0という範囲である。W is the most excellent element as a solid solution strengthening element that contributes to the creep strength of ferritic steel. In addition, since the AC1 point is raised, high-temperature tempering for the purpose of stabilizing the structure is enabled. W requires a minimum of 1% addition. However, an excessive addition causes a serious adverse effect that δ ferrite is precipitated to cause a significant decrease in toughness. On the other hand, Co
It is an important element that offsets the problem of precipitation of δ ferrite caused by addition, and requires at least 1.5%. However, excessive addition lowers the AC1 point, so that high-temperature tempering becomes impossible and the structure cannot be stabilized. As described above, W and Co are elements that give mutually contradictory effects, and an appropriate addition balance in the present alloy system is in a range of 1 ≧ 1.5W−Co ≧ 0.
第1表は、供試鋼の化学組成、600℃、20kgf/mm2の条
件のクラープ試験での破断寿命、0℃でのシャルビー衝
撃試験での吸収エネルギーを示す。Table 1 shows the chemical composition of the test steel, the fracture life in the clap test under the conditions of 600 ° C. and 20 kgf / mm 2 , and the absorbed energy in the Charby impact test at 0 ° C.
第1表に示す鋼のうち、No.1〜No.4は本発明鋼であ
り、その他は比較鋼である。比較鋼No.5とNo.6は1.5W−
Co<0、No.7とNo.8は1.5−Co>1であり、いずれもW
とCoの添加バランスが適切ではない。また比較鋼No.9は
Moが0.5%以下、比較鋼No.10はVが0.05%以下、比較鋼
No.11はNbが0.01%以下と、それぞれ重要な強化元素が
本発明範囲を下回って添加されている。さらに比較鋼N
o.12はMoが本発明範囲以上添加されている。In the steels shown in Table 1, No. 1 to No. 4 are steels of the present invention, and others are comparative steels. Comparative steel No.5 and No.6 are 1.5W−
Co <0, No.7 and No.8 have 1.5−Co> 1, and both are W
And Co addition balance is not appropriate. Comparative steel No. 9
Mo is 0.5% or less, V of comparative steel No.10 is 0.05% or less, comparative steel
In No. 11, Nb is 0.01% or less, and each important strengthening element is added below the scope of the present invention. Further comparison steel N
In the case of o.12, Mo is added in an amount exceeding the range of the present invention.
比較鋼No.5とNo.6はクリープ変形中における顕著な組
織変化のため破断寿命が短く、一方比較鋼No.7とNo.8は
フェライト析出のための靭性が著しく低い。また比較鋼
No.9〜No.11は強化元素不足のためクリープ破断寿命が
短い。比較鋼No.12はMoの過剰添加のため靭性が低い。
それに対し、本発明鋼No.1〜No.4はいずれも充分なクリ
ープ破断寿命と靭性を有し、申し分の無い特性が得られ
ている。Comparative steels No. 5 and No. 6 have a short fracture life due to remarkable structural change during creep deformation, while comparative steels No. 7 and No. 8 have significantly lower toughness due to ferrite precipitation. Also compare steel
No. 9 to No. 11 have short creep rupture lives due to lack of reinforcing elements. Comparative steel No. 12 has low toughness due to excessive addition of Mo.
On the other hand, all of the steels Nos. 1 to 4 of the present invention have sufficient creep rupture life and toughness, and satisfactory properties are obtained.
〔発明の効果〕 以上述べたように、本発明は高Cr系のフェライト系耐
熱鋼に適切なバランスのWとCoを添加することによっ
て、高い靭性を備えた高クリープ強度鋼を提供するもの
であり、その果たす役割は工業上極めて有意義なもので
ある。 [Effects of the Invention] As described above, the present invention provides a high creep strength steel with high toughness by adding W and Co in an appropriate balance to a high Cr ferritic heat resistant steel. Yes, its role is very significant in industry.
フロントページの続き (56)参考文献 特開 昭60−165359(JP,A) 特開 昭61−133365(JP,A) 特開 昭60−13056(JP,A) 特公 昭47−29090(JP,B1) (58)調査した分野(Int.Cl.6,DB名) C22C 38/00 - 38/60Continuation of front page (56) References JP-A-60-165359 (JP, A) JP-A-61-133365 (JP, A) JP-A-60-13056 (JP, A) JP-B-47-29090 (JP, A) , B1) (58) Field surveyed (Int. Cl. 6 , DB name) C22C 38/00-38/60
Claims (1)
oの添加量の間に、 1≧1.5W−Co≧0 なる関係が成立し、残部Fe及び不可避的不純物からなる
ことを特徴とする高強度、高靭性フェライト系耐熱鋼。C. 0.03 to 0.2%, Si: 0.05 to 1%, Mn: 0.1 to 1.5%, Cr: 8 to 13%, Ni: 0.01 to 1%, by weight ratio of each element. Mo: 0.5 to 1.5%, V: 0.05 to 0.5%, Nb: 0.01 to 0.15%, N: 0.002 to 0.1%, and containing 1% or more of W, 1.5% or more of Co, W and C
A high-strength, high-toughness ferritic heat-resistant steel characterized in that the relation of 1 ≧ 1.5W−Co ≧ 0 is established between the amounts of o added, and the balance consists of Fe and unavoidable impurities.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18363889A JP2834196B2 (en) | 1989-07-18 | 1989-07-18 | High strength, high toughness ferritic heat resistant steel |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18363889A JP2834196B2 (en) | 1989-07-18 | 1989-07-18 | High strength, high toughness ferritic heat resistant steel |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0353047A JPH0353047A (en) | 1991-03-07 |
JP2834196B2 true JP2834196B2 (en) | 1998-12-09 |
Family
ID=16139285
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP18363889A Expired - Fee Related JP2834196B2 (en) | 1989-07-18 | 1989-07-18 | High strength, high toughness ferritic heat resistant steel |
Country Status (1)
Country | Link |
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JP (1) | JP2834196B2 (en) |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2947913B2 (en) * | 1990-10-12 | 1999-09-13 | 株式会社日立製作所 | Rotor shaft for high temperature steam turbine and method of manufacturing the same |
JP2689198B2 (en) * | 1992-05-14 | 1997-12-10 | 新日本製鐵株式会社 | Martensitic heat resistant steel with excellent creep strength |
US5415706A (en) * | 1993-05-28 | 1995-05-16 | Abb Management Ag | Heat- and creep-resistant steel having a martensitic microstructure produced by a heat-treatment process |
JPH083697A (en) * | 1994-06-13 | 1996-01-09 | Japan Steel Works Ltd:The | Heat resistant steel |
JP3315702B2 (en) * | 1994-07-06 | 2002-08-19 | 正彦 森永 | Method for producing ferritic iron-based alloy and heat-resistant ferritic steel |
JP3480061B2 (en) * | 1994-09-20 | 2003-12-15 | 住友金属工業株式会社 | High Cr ferritic heat resistant steel |
JPH1136038A (en) * | 1997-07-16 | 1999-02-09 | Mitsubishi Heavy Ind Ltd | Heat resistant cast steel |
EP0903421B1 (en) * | 1997-09-22 | 2004-11-24 | National Research Institute For Metals | Ferritic heat-resistant steel and method for producing it |
FR2823226B1 (en) * | 2001-04-04 | 2004-02-20 | V & M France | STEEL AND STEEL TUBE FOR HIGH TEMPERATURE USE |
-
1989
- 1989-07-18 JP JP18363889A patent/JP2834196B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
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JPH0353047A (en) | 1991-03-07 |
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