JPH0543986A - High chromium ferritic heat resisting steel reduced in deterioration in strength in weld heat-affected zone - Google Patents
High chromium ferritic heat resisting steel reduced in deterioration in strength in weld heat-affected zoneInfo
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- JPH0543986A JPH0543986A JP20164491A JP20164491A JPH0543986A JP H0543986 A JPH0543986 A JP H0543986A JP 20164491 A JP20164491 A JP 20164491A JP 20164491 A JP20164491 A JP 20164491A JP H0543986 A JPH0543986 A JP H0543986A
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- heat
- affected zone
- creep
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Abstract
Description
【0001】[0001]
【産業上の利用分野】この発明は高温強度が高く、耐酸
化性および溶接性に優れ、ボイラー、原子力、化学工業
などの分野で高温耐圧部材として使用される例えば鋼
管、鋼板鍛造材に供される鋼であって、特に溶接継手の
熱影響部における強度低下の小さい高クロムフェライト
系耐熱鋼に関する。BACKGROUND OF THE INVENTION The present invention has high strength at high temperature, excellent oxidation resistance and weldability, and is used as a high temperature pressure resistant member in the fields of boiler, nuclear power, chemical industry and the like, for example, for steel pipes and steel plate forgings. The present invention relates to a high-chromium ferritic heat-resisting steel having a small strength reduction particularly in the heat-affected zone of a welded joint.
【0002】[0002]
【従来の技術】ボイラー、原子力、化学工業用等の高温
耐熱耐圧部材に使用される耐熱鋼は、高温強度、耐食
性、耐酸化性および靱性とともに、加工性、溶接性、経
済性に優れていることが要求される。従来、上記のよう
な用途に用いられる材料としては、SUS321H 、SUS347
H 鋼などのオーステナイトステンレス鋼、 2・ 1/4 C
r−1Mo鋼などの低合金鋼、9〜12Cr系の高Crフェラ
イト鋼がある。中でもの高Crフェライト鋼は、500 〜
650 ℃の温度において強度、耐食性の点での低合金鋼
より優れ、またのオーステナイトステンレス鋼に比べ
て熱伝導度が高く、熱膨張係数が小さいことから耐熱疲
労特性に優れるとともにスケールの剥離をおこしにくい
こと、応力腐食割れをおこさないことが利点である。2. Description of the Related Art Heat-resistant steel used for high-temperature heat-resistant pressure-resistant members for boilers, nuclear power plants, chemical industries, etc. has excellent workability, weldability, and economic efficiency as well as high-temperature strength, corrosion resistance, oxidation resistance and toughness. Is required. Conventionally, as materials used for the above-mentioned applications, SUS321H, SUS347
Austenitic stainless steel such as H steel, 2/1/4 C
There are low alloy steels such as r-1Mo steel and high Cr ferritic steels of 9-12Cr series. Among them, high Cr ferritic steel is 500 ~
It is superior in strength and corrosion resistance to low alloy steels at a temperature of 650 ° C, has a higher thermal conductivity than austenitic stainless steels, and has a low coefficient of thermal expansion, resulting in excellent thermal fatigue resistance and scale delamination. The advantages are that it is difficult and stress corrosion cracking does not occur.
【0003】高Crフェライト鋼としては、9Cr−1Mo鋼
(STBA26) 、改良9Cr−1Mo鋼(ASTM SA213 T91)、12Cr
−1Mo鋼(DIN X20CrMoV121)などが著名である。さらに
高温強度を改善することを目的にMo、W、V、Nb、N等
を複合添加した鋼として特公昭62−8502号、同62−1230
4 号、特開昭62−297435号、特開平2−310340号の公報
に開示される鋼がある。As high Cr ferritic steels, 9Cr-1Mo steel (STBA26), improved 9Cr-1Mo steel (ASTM SA213 T91), 12Cr
-1Mo steel (DIN X20CrMoV121) etc. are well known. Further, as a steel to which Mo, W, V, Nb, N, etc. are added in combination for the purpose of improving high temperature strength, Japanese Patent Publication Nos. 628502 and 62-1230.
There are steels disclosed in JP-A Nos. 62-297435 and 2-310340.
【0004】本発明者らは 600℃以上の高温耐酸化性を
高めることを目的として耐熱材料の組成等に関する研究
を重ねてきた。その成果は、Cu添加鋼として特開平2−
232345号、同3−97832 号の公報に提案したとおりであ
る。このCu添加は 600℃以上の耐酸化性改善に加え、高
Crフェライト鋼に生成しやすいδ−フェライトの抑制に
効果があり、高価なNiの節約になる。また、C、Niに比
べてAc1 変態温度を下げにくいことも特徴で、製造時の
熱処理条件選定の上で有利である。なお、Cu添加鋼は特
開平2−294452公報にも提案されており、同公報にはCu
の添加が溶接継手の靱性、特に長時間加熱後の溶接部の
靱性維持に有効であると記載されている。The present inventors have conducted extensive research on the composition of heat-resistant materials for the purpose of improving high-temperature oxidation resistance at 600 ° C. or higher. The result is that as a Cu-added steel
This is as proposed in the publications of 232345 and 3-97832. This Cu addition improves the oxidation resistance above 600 ℃ and
Cr is effective in suppressing δ-ferrite, which is easily generated in ferritic steel, and saves expensive Ni. It is also characterized in that it is difficult to lower the Ac 1 transformation temperature as compared with C and Ni, which is advantageous in selecting heat treatment conditions during manufacturing. Note that Cu-added steel is also proposed in Japanese Patent Laid-Open No. 2-294452, and in that publication, Cu is added.
It is described that the addition of is effective for maintaining the toughness of a welded joint, particularly the toughness of a welded part after heating for a long time.
【0005】高Cr鋼にCuを添加する試みは従来からなさ
れている。例えば特公昭46−15210号公報には1〜
4%のCuが焼入れ性、靱性の向上に効果があることが
示されており、同じく特開昭60−155649号公報には1%
以下のCuは靱性の改善に効果があることが示されてい
る。さらに前掲の特公昭62−12304 号公報や、特開昭59
−211553号公報にもCuを添加した高Cr鋼が開示されてい
る。Attempts have been made to add Cu to high Cr steels. For example, Japanese Patent Publication No. 46-15210 discloses 1
It has been shown that 4% of Cu is effective in improving hardenability and toughness, and 1% is also disclosed in JP-A-60-155649.
The following Cu has been shown to be effective in improving toughness. Further, the above-mentioned Japanese Patent Publication No. 12304/1987 and Japanese Patent Laid-Open No. 59/1985.
-211553 also discloses a high Cr steel containing Cu.
【0006】しかしながら、これまでに提案された高Cr
フェライト鋼には、溶接継手の熱影響部(以下HAZと
いう)の軟化が大きくクリープ強度が低下するという共
通の問題がある。前述のような従来の高Crフェライト鋼
は、母材の高温クリープ強度の改善を重視している反
面、母材に比較して溶接継手部の強度低下が大きいとい
う問題点についての検討は殆どなされていない。上記の
多くの特許公報に開示されている発明も、すべて母材特
性を重視した組成の発明で、溶接継手のHAZの組織変
化とこれに伴うHAZの強度低下に対する配慮は何らな
されていない。However, the high Cr content proposed so far
Ferrite steel has a common problem that the heat-affected zone (hereinafter referred to as HAZ) of the welded joint is largely softened and the creep strength is lowered. As described above, the conventional high Cr ferritic steel emphasizes the improvement of the high temperature creep strength of the base metal, but on the other hand, almost no study has been conducted on the problem that the strength of the welded joint is much lower than that of the base metal. Not not. The inventions disclosed in the above-mentioned many patent publications are all inventions in which the composition of the base material is emphasized, and no consideration is given to the structural change of the HAZ of the welded joint and the accompanying reduction in the strength of the HAZ.
【0007】以上要するに高強度高Crフェライト鋼の溶
接継手の軟化層に起因するクリープ強度低下が、この種
の鋼を高温耐圧部材として使用するに当たり大きな障害
となってきた。In summary, the decrease in creep strength due to the softened layer of the welded joint of high strength and high Cr ferritic steel has been a major obstacle in using this type of steel as a high temperature pressure resistant member.
【0008】[0008]
【発明が解決しようとする課題】高Crフェライト耐熱鋼
における溶接継手部の強度低下は、HAZに生成する不
安定な軟化層に起因するものと考えられるが、これを防
ぐ根本的な対策についての報告はない。例えば、既存の
改良9Cr−1Moの鋼の溶接継手では 600〜650 ℃クリー
プ強度が104 h 以上の長時間側で母材に比べ15〜20%低
下する。このようなクリープ強度の低下は、高W系の高
Crフェライト鋼でも同じである。The decrease in strength of the welded joint in high Cr ferritic heat resistant steel is considered to be due to the unstable softened layer formed in the HAZ. There is no report. For example, in the existing welded joint of improved 9Cr-1Mo steel, the creep strength at 600 to 650 ° C is 15 to 20% lower than that of the base metal on the long side of 10 4 h or more. Such decrease in creep strength is due to the high
The same applies to Cr ferritic steel.
【0009】本発明の課題は、高温強度、加工性、溶接
性等の基本性質は従来鋼と同等以上であって、特に溶接
継手部の軟化が小さく、高温クリープ強度の低下がな
く、しかも安価な高Crフェライト系耐熱鋼を提供するこ
とにある。The object of the present invention is that the basic properties such as high temperature strength, workability and weldability are equal to or higher than those of conventional steels, especially the softening of the welded joint is small, the high temperature creep strength is not lowered, and the cost is low. To provide a high Cr ferritic heat resistant steel.
【0010】[0010]
【課題を解決するための手段】溶接継手部のクリープ強
度の低下は、HAZ部の軟化層の形成によっておこる延
性の低い剪断的な破壊(Type IV のクラッキングと呼
ぶ) を伴うのが特徴である。一方、高強度化の観点から
Wを多量添加した鋼では、継手部のクリープ強度の低下
が母材強度に比べてきわめて大きい。また、多量のWの
添加は材料コストを上げるという難点もある。[Means for Solving the Problems] The decrease in creep strength of welded joints is characterized by low ductility shear fracture (called Type IV cracking) caused by the formation of a softened layer in the HAZ portion. .. On the other hand, in the steel containing a large amount of W from the viewpoint of increasing the strength, the decrease in creep strength of the joint portion is extremely larger than the strength of the base metal. Further, addition of a large amount of W has a drawback of increasing material cost.
【0011】本発明は、高Crフェライト鋼に関する多数
の研究結果から得られた下記の知見を基礎としてなされ
たものである。The present invention is based on the following findings obtained from many research results on high Cr ferritic steel.
【0012】Cuの添加によりHAZの組織安定性が高
まり、溶接継手部の軟化が防止できる。この作用は、δ
−フェライトの抑制、靱性の改善等のこれまでに知られ
た作用とは異なるもので、後述する特定の化学組成範囲
においてのみ得られるものである。The addition of Cu enhances the HAZ structure stability and prevents the softening of the welded joint. This action is
-It is different from the previously known actions such as suppression of ferrite and improvement of toughness, and is obtained only in the specific chemical composition range described later.
【0013】Wを多く添加した高Crフェライト鋼は母
材の強度が高まる反面、継手強度が大きく低下する。W
を添加せず、またはその添加量を最小限に抑えて、母材
の強度を多少落としても、Cuの添加により継手のクリー
プ強度を向上させることにより部材は高応力下での使用
が可能になる。In the high Cr ferritic steel containing a large amount of W, the strength of the base material is increased, but the joint strength is greatly reduced. W
Even if the strength of the base material is slightly reduced by adding no or adding a minimum amount of Cu, the addition of Cu improves the creep strength of the joint so that the member can be used under high stress. Become.
【0014】上記およびの効果を得るには、鋼に
Alを添加して十分な脱酸をすることが必須である。Alの
添加量が少ないと継手強度は大きく低下する。一方、Al
の過剰添加は母材を含めて強度低下を招く。To obtain the above effects and
It is essential to add Al for sufficient deoxidation. If the amount of Al added is small, the joint strength will drop significantly. On the other hand, Al
Excessive addition of Al reduces the strength including the base metal.
【0015】本発明は、主に上記の知見を基にしてなさ
れたもので、その要旨は下記の高Crフェライト耐熱鋼に
ある。The present invention was mainly made on the basis of the above findings, and its gist resides in the following high Cr ferritic heat resistant steel.
【0016】(1) 重量%で、C:0.03〜0.15%、Si:0.
7 %以下、Mn: 0.1〜1.5 %、Ni:0.05〜1.0 %、Cr:
8〜14%、Mo:0.01〜3%、V: 0.1〜0.3 %、Nb:0.
01〜0.2 %、N: 0.001〜0.1 %、Al: 0.001〜0.05
%、Cu: 0.4〜3.5 %を含み、残部は鉄および不可避的
不純物からなり、不純物としてのO (固溶酸素) が0.01
5%以下である溶接熱影響部の強度低下の小さい高クロ
ムフェライト耐熱鋼。(1) C: 0.03 to 0.15% by weight, Si: 0.
7% or less, Mn: 0.1 to 1.5%, Ni: 0.05 to 1.0%, Cr:
8-14%, Mo: 0.01-3%, V: 0.1-0.3%, Nb: 0.
01 to 0.2%, N: 0.001 to 0.1%, Al: 0.001 to 0.05
%, Cu: 0.4 to 3.5%, the balance consisting of iron and unavoidable impurities, and O (solid solution oxygen) as impurities of 0.01
High chrome ferritic heat resistant steel with less than 5% strength reduction in the weld heat affected zone.
【0017】(2) 合金成分として上記(1) 記載の成分の
外に更に、下記の (イ)〜 (ニ)群の一つ以上の群から選ん
だ1種以上の成分を含有する高クロムフェライト耐熱
鋼。(2) A high chromium content containing, as an alloy component, one or more components selected from one or more of the following (a) to (d) groups in addition to the components described in (1) above. Ferrite heat resistant steel.
【0018】 (イ)群・・・0.0001〜0.02重量%のB (ロ)群・・・0.5 重量%未満のW (ハ)群・・・0.0001〜0.1 %のMg (ニ)群・・・それぞれ0.01〜0.2 重量%のLa、Ce、Ca、Z
r、Ti、YおよびTa 上記本発明鋼は、後述するように多数の合金成分を適正
な量でバランスよく含有することによって耐熱鋼として
総合的特性の極めて優れたものである。特に本発明鋼
は、適量のAl添加により十分脱酸し、W量を低減または
無添加としてCu添加し、HAZ軟化によるTypeIVクラッ
クを防止できることが大きな特徴である。Group (a): 0.0001 to 0.02% by weight of B (b) group: less than 0.5% by weight of W (c) group: 0.0001 to 0.1% of Mg (d) group: 0.01-0.2 wt% La, Ce, Ca, Z respectively
r, Ti, Y and Ta The steels of the present invention described above are excellent in overall characteristics as heat resistant steels by containing a large number of alloy components in proper amounts in a well-balanced manner as described later. In particular, the steel of the present invention is characterized by being sufficiently deoxidized by adding an appropriate amount of Al, reducing the W amount or adding Cu without adding W, and preventing Type IV cracks due to HAZ softening.
【0019】W量の少ないもしくはWを添加しない高Cr
フェライト鋼であっても十分なクリープ破断強度が得ら
れる。High Cr with a small amount of W or no W added
Sufficient creep rupture strength can be obtained even with ferritic steel.
【0020】[0020]
【作用】以下、本発明鋼の合金成分の作用効果とその含
有量の限定理由を説明する。なお、合金成分の含有量に
ついての%は全て重量%である C:CはCr、Fe、W、VおよびNbと結合して炭化物を形
成し、高温強度に寄与するとともにそれ自身がオーステ
ナイト安定化元素として組織を安定化する。0.03%未満
では炭化物の析出量が少なく、δ−フェライトの多量生
成を招き強度と靱性が低下する。また0.15%を超える場
合には、鋼が著しく硬化して溶接性、加工性が悪くな
る。即ち、Cの適正含有量は0.03〜0.15%である。一層
好ましい範囲は0.06〜0.13%である。The function and effect of the alloy components of the steel of the present invention and the reason for limiting the content thereof will be described below. In addition, all% of the content of alloy components are weight%. C: C combines with Cr, Fe, W, V and Nb to form a carbide, contributes to high temperature strength and stabilizes itself by austenite. Stabilizes the structure as an element. If it is less than 0.03%, the precipitation amount of carbides is small and a large amount of δ-ferrite is produced, resulting in a decrease in strength and toughness. On the other hand, if it exceeds 0.15%, the steel is significantly hardened and the weldability and workability are deteriorated. That is, the proper content of C is 0.03 to 0.15%. A more preferable range is 0.06 to 0.13%.
【0021】Si:Siは脱酸剤として働き、また鋼の耐水
蒸気酸化特性を高める元素である。しかし、Siが 0.7%
を超えると鋼の靱性が著しく低下し、クリープ強度に対
しても有害である。特に肉厚材料では長時間加熱による
脆化を避けるためにも低く抑えるのが望ましいから上限
を 0.7%とする。Si: Si is an element that acts as a deoxidizer and enhances the steam oxidation resistance of steel. However, Si is 0.7%
If it exceeds 1.0, the toughness of the steel is remarkably reduced and it is harmful to the creep strength. Especially for thick materials, it is desirable to keep it low to avoid embrittlement due to long-term heating, so the upper limit is made 0.7%.
【0022】Mn:Mnは熱間加工性を改善し、組織の安定
化に有効でるが、0.1 %未満では十分な効果が得られ
ず、1.5 %を超えると鋼を硬化させ、加工性、溶接性を
損なう。よってMnの含有量は 0.1〜1.5 %とする。Mn: Mn improves hot workability and is effective in stabilizing the structure, but if it is less than 0.1%, a sufficient effect cannot be obtained, and if it exceeds 1.5%, it hardens the steel to improve workability and welding. Impair sex. Therefore, the Mn content is 0.1 to 1.5%.
【0023】Ni:Niはオーステナイト安定化元素として
δ−フェライトの生成を抑制し、焼もどしマルテンサイ
ト組織を安定にする。また、Cu添加鋼の熱間加工性改善
の点からもCuの含有量に見合った適量のNiを添加する必
要がある。Ni0.05%未満では上記の効果は得られず、1.
0 %を超えるとクリープ強度が低下し、また経済性を損
なう。従って、Niの含有量は0.05〜1.0 %とする。望ま
しい範囲は0.1〜0.8 %である。さらに好ましいのは重
量%比でCu/Ni= 2.5〜4.5 とすることである。このCu
/Ni比は、Cu含有鋼に特有の熱間加工時の割れを防止す
る対策としての条件である。Ni: Ni suppresses the formation of δ-ferrite as an austenite stabilizing element and stabilizes the tempered martensite structure. Also, from the viewpoint of improving the hot workability of Cu-added steel, it is necessary to add an appropriate amount of Ni in proportion to the Cu content. If the Ni content is less than 0.05%, the above effect cannot be obtained.
If it exceeds 0%, the creep strength will decrease and the economy will be impaired. Therefore, the Ni content is 0.05 to 1.0%. A desirable range is 0.1 to 0.8%. More preferably, the weight ratio is Cu / Ni = 2.5 to 4.5. This Cu
The / Ni ratio is a condition as a measure to prevent cracks during hot working, which is peculiar to Cu-containing steel.
【0024】Cr:Crは鋼の耐酸化性、高温耐食性を確保
するために不可欠な元素であり、その含有量が8%未満
では高Cr鋼としての前記のような用途に十分な耐酸化
性、高温耐食性が得られない。Crが8%未満の鋼では焼
ならしでベイナイトが多く生成し、本発明の対象とする
焼もどしマルテンサイト型の材料とは異なる材料とな
る。一方、Crが14%を超えるとδ−フェライト量の増加
により、強度、加工性、靱性が損なわれる。したがっ
て、Cr量は8〜14%が適正範囲であり、好ましいのは
8.5〜12%である。Cr: Cr is an indispensable element for ensuring the oxidation resistance and high temperature corrosion resistance of the steel, and if the content of Cr is less than 8%, the oxidation resistance is sufficient for the above-mentioned applications as a high Cr steel. , High temperature corrosion resistance cannot be obtained. In the steel containing Cr less than 8%, a large amount of bainite is formed by normalizing, and the material is different from the tempered martensite-type material targeted by the present invention. On the other hand, when Cr exceeds 14%, the amount of δ-ferrite increases, and the strength, workability and toughness are impaired. Therefore, the proper amount of Cr is 8 to 14%, and the preferable range is
It is 8.5 to 12%.
【0025】Mo:Moは本発明鋼の重要基本成分の一つ
で、固溶強化および微細炭窒化物の析出強化元素として
クリープ強度の向上に有効である。Moはδ−フェライト
を生成しやすいものの、Wに比べ安価であるという利点
がある。また、Wに比べ母材のクリープ強度への寄与は
やや小さいが、Mo含有鋼は溶接継手のクリープ強度低下
が小さい。これらの理由で、WよりもMoを積極的に利用
することが本発明の大きな特徴の一つである。Mo: Mo is one of the important basic components of the steel of the present invention, and is effective for improving the creep strength as a solid solution strengthening and precipitation strengthening element for fine carbonitrides. Although Mo easily forms δ-ferrite, it has an advantage that it is cheaper than W. Although the contribution of the base material to the creep strength is slightly smaller than that of W, the decrease in creep strength of the welded joint is small in the Mo-containing steel. For these reasons, the positive use of Mo rather than W is one of the major features of the present invention.
【0026】特にMo含有鋼の継手HAZの軟化層のクリ
ープ中の組織安定性は、後述の適正なAl脱酸とCu添加に
より著しく改善されることがわかった。これは、継手H
AZの軟化層へのクリープひずみの集中を抑制する結果
にもつながっている。しかし、このような効果は0.01%
未満のMoでは得られない。一方、Moが3%を超えるとδ
−フェライトが多量に生成するとともに鋼が硬化して靱
性、加工性が損なわれる。よって、Moの含有量は、0.01
〜3%の範囲とするのがよい。さらに好ましい範囲は
0.8〜2.2 %である。It has been found that the structural stability of the softened layer of the joint HAZ of the Mo-containing steel during creep is significantly improved by the appropriate Al deoxidation and Cu addition described later. This is joint H
This also results in suppressing the concentration of creep strain in the softened layer of AZ. However, such effect is 0.01%
Not available with less than Mo. On the other hand, when Mo exceeds 3%, δ
-A large amount of ferrite is generated and the steel is hardened to impair toughness and workability. Therefore, the Mo content is 0.01
It is preferable to be in the range of 3%. A more preferable range is
0.8 to 2.2%.
【0027】V:VはC、Nと結合してV(C、N)の
微細析出物を形成する。この析出物は高温、長時間の加
熱でも安定で長時間側のクリープ強度の向上に大きく寄
与する。V: V combines with C and N to form V (C, N) fine precipitates. These precipitates are stable even at high temperature for a long time and contribute greatly to the improvement of creep strength for a long time.
【0028】V含有量が 0.1%未満では上記の効果が十
分に得られず、0.3 %を超える場合には固溶Vが増加し
てかえって強度を損なう。したがってVの含有量は 0.1
〜0.3%とする。If the V content is less than 0.1%, the above effect cannot be sufficiently obtained, and if it exceeds 0.3%, the solid solution V increases and the strength is rather deteriorated. Therefore, the V content is 0.1
~ 0.3%
【0029】Nb:NbはVと同様C、Nと結合してNb
(C、N)の微細析出物を形成し、クリープ強度の向上
に寄与する。この析出物は短時間クリープ強度の向上に
有効で、さらに結晶粒を微細化し靱性改善にも有効であ
る。Nb含有量が0.01%未満では上記効果は得られない。
一方、0.2 %を超える場合は、焼ならし処理で未固溶Nb
Cが増え、強度と溶接性を損なう。したがってNbの含有
量は0.01〜0.2 %とする。Nb: Nb is the same as V and is bonded to C and N to form Nb.
It forms fine precipitates of (C, N) and contributes to the improvement of creep strength. This precipitate is effective for improving short-time creep strength, and is also effective for improving the toughness by refining the crystal grains. If the Nb content is less than 0.01%, the above effect cannot be obtained.
On the other hand, if it exceeds 0.2%, undissolved Nb is
C increases, and strength and weldability are impaired. Therefore, the Nb content is 0.01 to 0.2%.
【0030】N:NはV、Nbと結合して炭窒化物を形成
してクリープ強度の向上に寄与するが、0.001 %未満で
はその効果がない。一方、0.1 %を超える場合は溶接
性、加工性を損なう。よってNの含有量は 0.001〜0.1
%とした。好ましいのは0.02〜0.07%である。N: N combines with V and Nb to form a carbonitride and contributes to the improvement of creep strength, but if it is less than 0.001%, it has no effect. On the other hand, if it exceeds 0.1%, the weldability and workability are impaired. Therefore, the N content is 0.001 to 0.1
%. 0.02 to 0.07% is preferable.
【0031】Al:Alは、脱酸剤として添加されるが、後
述するように固溶酸素を低減してCuの作用効果を発揮さ
せるためにはAlによる脱酸を十分に行わなければならな
い。Alの含有量が 0.001%未満では十分な脱酸効果が得
られず、靱性、強度を損なう。一方、0.05%を超える場
合はクリープ強度を損なうことから、Al含有量は 0.001
〜0.05%とする。Al: Al is added as a deoxidizing agent, but as described below, deoxidation by Al must be sufficiently performed in order to reduce the solid solution oxygen and exert the effect of Cu. If the Al content is less than 0.001%, a sufficient deoxidizing effect cannot be obtained and the toughness and strength are impaired. On the other hand, if it exceeds 0.05%, the creep strength is impaired, so the Al content is 0.001
~ 0.05%.
【0032】Cu:Cuは本発明鋼の重要な添加元素の一つ
で、本発明の成分系の鋼を対象とした場合、次のような
作用効果をもつ。 溶接部に形成するHAZ軟化層の組織 (主に焼もど
しマルテンサイト組織でδ−フェライトを含むこともあ
る) の溶接および使用中の転位の回復、再結晶を抑制す
る。従って、軟化層ができても使用中の変化が小さく組
織が安定である。Cu: Cu is one of the important additive elements of the steel of the present invention, and has the following effects when the steel of the composition system of the present invention is targeted. Suppresses the recovery and recrystallization of dislocations during the welding and use of the structure of the HAZ softening layer formed in the weld (mainly tempered martensite structure and sometimes containing δ-ferrite). Therefore, even if a softened layer is formed, the change during use is small and the structure is stable.
【0033】 HAZ軟化層を固溶強化する。従っ
て、クリープ中の強度の低い部分 (軟化層) へのひずみ
集中を軽減し、クリープ抵抗を高める。Solid solution strengthening of the HAZ softening layer. Therefore, the strain concentration in the low strength portion (softening layer) during creep is reduced, and the creep resistance is increased.
【0034】 クリープ中の軟化層での局部変形破壊
はTypeIVクラッキングと呼ばれるが、とも関連してこ
の局部変形が少なくなる。TypeIVクラッキングは継手部
の低延性破壊であるが、Cuの添加は継手部の延性向上に
も寄与し、この破壊を防止する。Local deformation failure in the softening layer during creep is called Type IV cracking, and in connection with this local deformation is reduced. Type IV cracking is a low ductility fracture of the joint, but the addition of Cu also contributes to the ductility improvement of the joint and prevents this fracture.
【0035】これらのCuの作用効果は本発明者が新たに
見いだしたものであるが、その外に更に、溶接部のδ−
フェライトの抑制、靱性改善、焼入れ性改善、耐酸化性
向上にも有効である。ただし、Cu単独添加では、Cu相の
析出により脆化しやすく熱間加工性、クリープ延性を損
なうから、前記のNiと複合添加して用いる。そこでCuの
含有量が 0.4%未満では上記の効果が十分でなく、一
方、3.5 %を超えるとかえって加工性、延性を損なうば
かりか、残留オーステナイト相が増加しクリープ強度が
損なわれる。従って、Cuの含有量は 0.4〜3.5 %が適正
である。なお好ましい含有量は 0.8〜2.2 %である。These effects of Cu are newly found by the present inventor, and in addition to that, the δ-
It is also effective in suppressing ferrite, improving toughness, improving hardenability, and improving oxidation resistance. However, if Cu is added alone, it tends to become brittle due to the precipitation of Cu phase, and the hot workability and creep ductility are impaired. Therefore, if the Cu content is less than 0.4%, the above effect is not sufficient, while if it exceeds 3.5%, not only the workability and ductility are impaired, but also the retained austenite phase increases and the creep strength is impaired. Therefore, a Cu content of 0.4 to 3.5% is appropriate. The preferable content is 0.8 to 2.2%.
【0036】O (固溶酸素):Oは不純物である。本発
明では、十分脱酸を行う目安として残存する固溶酸素量
を 0.015%以下と規定する。O量が 0.015%を超えると
長時間クリープ強度と溶接継手部の靱性を損なう。特に
継手部のHAZにおいて固溶酸素の低減が使用中の組織
の回復、軟化を抑制するのに重要である。また、Cuの固
溶強化の作用を生かすのにも酸素の低減は有効である。O (solid solution oxygen): O is an impurity. In the present invention, the amount of solid solution oxygen remaining is defined as 0.015% or less as a guide for performing sufficient deoxidation. If the O content exceeds 0.015%, the long-term creep strength and the toughness of the welded joint are impaired. In particular, in the HAZ of the joint, the reduction of dissolved oxygen is important for suppressing the recovery and softening of the structure during use. Further, the reduction of oxygen is also effective in utilizing the effect of Cu for solid solution strengthening.
【0037】本発明鋼は、上記各成分の他に、前述の
(イ)〜 (ニ)群の成分を必要に応じて含有することができ
る。The steel of the present invention, in addition to the above components,
The components of the groups (A) to (D) can be contained as necessary.
【0038】(イ)群 (B) :Bは微量添加により炭化物
を分散、安定化させる効果がある。0.0001%未満ではそ
の効果が小さく、0.02%を超えると溶接性と加工性を損
なうから、Bを添加する場合はその含有量を0.0001〜0.
02%の範囲にするのがよい。(A) Group (B): B has the effect of dispersing and stabilizing the carbide by adding a trace amount. If it is less than 0.0001%, its effect is small, and if it exceeds 0.02%, the weldability and workability are impaired, so when B is added, its content is 0.0001-0.
It is good to set it in the range of 02%.
【0039】(ロ)群 (W) :WはMoと同様に、固溶強化
および微細炭化物析出強化元素としてクリープ強度の向
上に有効である。通常、Moの2倍(重量比)添加すると
高温側のクリープ強度に有効であるが、母材強度が高く
なる反面、溶接継手部の軟化、強度低下が相対的に大き
くなる。また、Wは、クリープ延性および靱性の点でも
Moより不利である。本発明は、溶接継手の強度低下を小
さくすることが目的であるから、Wは使用しないか、す
るとしてもその含有量は低く抑えることとした。Wの含
有量が0.5%以上の場合は、HAZ軟化が大きく継手の
クリープ強度を損なう。従って、Wを添加する場合でも
その含有量は 0.5%より低く抑えるべきである。Group (B) (W): W, like Mo, is effective as a solid solution strengthening and fine carbide precipitation strengthening element for improving creep strength. Usually, addition of twice Mo (weight ratio) is effective for creep strength on the high temperature side, but the strength of the base metal increases, but softening of the welded joint and strength reduction relatively increase. Further, W is also in terms of creep ductility and toughness.
It has a disadvantage over Mo. Since the purpose of the present invention is to reduce the decrease in strength of the welded joint, W is not used, or the content thereof is kept low. If the W content is 0.5% or more, HAZ softening becomes large and the creep strength of the joint is impaired. Therefore, even if W is added, its content should be kept below 0.5%.
【0040】(ハ)群 (Mg) :Mgは鋼の熱間加工性の改善
に有効で、かつ不純物のS、Oとの結合力が高く、これ
らの元素の害を除くのにも寄与する。0.0001%未満では
上記の効果が得られず、0.1 %を超える含有量になると
強度、靱性を著しく損なうため、Mgを使用刷る場合は、
その含有量は0.0001〜0.1 %とする。(C) Group (Mg): Mg is effective in improving the hot workability of steel, and has a high bonding strength with impurities S and O, and also contributes to the elimination of the damage of these elements. .. If it is less than 0.0001%, the above effect cannot be obtained, and if it exceeds 0.1%, the strength and toughness are significantly impaired.
The content is 0.0001 to 0.1%.
【0041】(ニ)群 (La、Ce、Ca、Zr、Ti、Y、Ta) :
これらの元素は、鋼中のP、S、Oなどの不純物と結合
させ、これらの析出物(介在物)の形態抑制を行わせる
ために必要に応じて添加する。これらの元素のうち少な
くとも1種をそれぞれの元素について0.01%以上添加す
ることによって上記不純物元素を安定かつ無害な析出物
として固定し、強度と靱性を向上させることができる。
しかし、それぞれ 0.2%を超えると介在物が増加しかえ
って強度、靱性を損なうので、それぞれの含有量は0.01
〜0.2 %とする。Group D (La, Ce, Ca, Zr, Ti, Y, Ta):
These elements are added as necessary in order to combine with impurities such as P, S, and O in the steel and suppress the morphology of these precipitates (inclusions). By adding at least one of these elements in an amount of 0.01% or more for each element, the impurity element can be fixed as a stable and harmless precipitate, and the strength and toughness can be improved.
However, if the content of each exceeds 0.2%, inclusions increase and the strength and toughness are impaired.
~ 0.2%
【0042】本発明鋼は前述の成分のほか、残部はFeと
不可避不純物からなる。鋼の不純物として代表的なもの
はPとSである。Pは 0.025%以下、Sは 0.015%以下
に抑えるべきである。これらはいずれも靱性、加工性、
溶接性に有害な元素であるので、上記の許容上限値以下
でもできるだけ少ない方がよい。The steel of the present invention comprises, in addition to the above components, the balance of Fe and inevitable impurities. Typical impurities of steel are P and S. P should be 0.025% or less and S should be 0.015% or less. These are all toughness, workability,
Since it is an element that is detrimental to weldability, it should be as small as possible even below the above allowable upper limit.
【0043】本発明鋼は焼もどしマルテンサイト組織と
して使用する。この焼もどしマルテンサイト組織中のδ
−フェライト量は、溶接継手部の靱性を向上させるため
にはできるだけ低い方が望ましい。HAZの延性改善に
はδ−フェライトは30%未満に抑えるのがよく、靱性、
クリープ強度を重視すればδ−フェライト量は5%未満
がよい。The steel of the present invention is used as a tempered martensite structure. Δ in this tempered martensite structure
-The amount of ferrite is preferably as low as possible in order to improve the toughness of the welded joint. In order to improve the ductility of HAZ, δ-ferrite should be kept below 30%, toughness,
If importance is attached to creep strength, the amount of δ-ferrite is preferably less than 5%.
【0044】本発明鋼の標準的な熱処理は焼ならし−焼
もどし処理である。焼ならし処理温度は、前の加工で生
じる粗大析出物を十分固溶させるとともに鋳造偏析等に
よる固溶合金元素の偏析を均一化する目的で、 Ac3変態
点以上とする。上限はδ−フェライトの多量析出抑制の
ため1150℃までとする。望ましい温度範囲は1000〜1100
℃である。The standard heat treatment for the steels of the present invention is the normalizing-tempering process. The normalizing treatment temperature is set to an Ac 3 transformation point or higher in order to sufficiently dissolve the coarse precipitates generated in the previous working and to homogenize the segregation of the solid solution alloy elements due to casting segregation or the like. The upper limit is 1150 ° C to prevent large precipitation of δ-ferrite. The preferred temperature range is 1000-1100
℃.
【0045】焼ならし後は焼もどし処理を行う。この焼
もどし処理は、高温クリープ強度の安定化のためにマル
テンサイト中の転位密度を低くする必要から、使用温度
よりも 150〜200 ℃以上高く、かつAc1 変態点以下の温
度域で行う。具体的には 750〜830 ℃が適当である。な
お焼もどしが不十分な場合は高温長時間側で著しい強度
低下を生ずることがある。これは特に溶接継手部で顕著
であるから、十分な焼もどしを行うように留意する必要
がある。After normalizing, a tempering process is performed. This tempering treatment is performed in a temperature range of 150 to 200 ° C. higher than the operating temperature and lower than the Ac 1 transformation point because it is necessary to lower the dislocation density in martensite in order to stabilize the high temperature creep strength. Specifically, 750 to 830 ° C is suitable. In addition, if tempering is insufficient, a significant decrease in strength may occur at high temperature for a long time. Since this is particularly remarkable at the welded joint, it is necessary to take care to perform sufficient tempering.
【0046】[0046]
【実施例】表1に示す化学組成の鋼を150Kg 真空溶解炉
で溶解し、インゴットを1150〜950 ℃で鍛造して厚さ20
mmの板とした。[Example] Steel having the chemical composition shown in Table 1 was melted in a 150 kg vacuum melting furnace, and an ingot was forged at 1150 to 950 ° C to obtain a thickness of 20.
mm plate.
【0047】符号A1の鋼はSTBA26、符号A2の鋼は
(火)STBA27 (火力原子力発電協会規格) 、符号A3の
鋼はASTM SA213 T91、符号A4の鋼は DIN X20CrMoWV12
1 で、いずれも既存の代表的な高Crフェライト鋼であ
る。符号A5〜A10の鋼はA3鋼をベースにCuを添加し
た比較鋼、A11、A12鋼は過剰のMoとWを複合添加した
Cu含有の比較鋼である。符号B1〜B25の鋼が本発明鋼
である。The steel with the code A1 is STBA26, and the steel with the code A2 is
(Tue) STBA27 (Thermal and Nuclear Power Association Standard), Steel with code A3 is ASTM SA213 T91, Steel with code A4 is DIN X20CrMoWV12
1 is a typical existing high Cr ferritic steel. Steels A5 to A10 are comparative steels in which Cu is added to the base of A3 steel, and steels A11 and A12 are combined additions of excess Mo and W.
It is a comparative steel containing Cu. The steels denoted by B1 to B25 are the steels of the present invention.
【0048】符号A1およびA2鋼は通常の熱処理とし
て 950℃×1時間→空冷後、750 ℃×1時間→空冷を行
った。符号A3〜A12および符号B1〜B25の鋼は、10
50℃×1時間→空冷の焼ならしと 780℃×3時間→空冷
の焼もどしを行った。The steels A1 and A2 were subjected to normal heat treatment at 950 ° C. × 1 hour → air cooling and then at 750 ° C. × 1 hour → air cooling. The steels with symbols A3 to A12 and symbols B1 to B25 are 10
50 ℃ × 1 hour → air-cooled normalization and 780 ℃ × 3 hours → air-cooled tempering.
【0049】溶接継手は、厚さ20mmの板をほぼ貫通する
ようにTIG溶接ビードを盛り、その後 740℃×5時間
空冷の後熱処理を行って作製した。The welded joint was prepared by placing TIG weld beads so as to almost penetrate a plate having a thickness of 20 mm, and then air-cooling at 740 ° C. for 5 hours, followed by heat treatment.
【0050】クリープ試験片はいずれもこのビードに垂
直に肉盛中央部から採取した。母材の常温引張試験片は
φ6mm×GL 30mm とし、継手クリープ試験は同じφ6mm
×GL 30mm の試験片を用い、平行部に溶金、熱影響部お
よび母材が入るように採取した。クリープ試験は 650℃
にて最長 10000時間程度行った。All creep test pieces were sampled from the center of the build-up perpendicular to this bead. The normal temperature tensile test piece of the base material is φ6 mm × GL 30 mm, and the joint creep test is the same φ6 mm
A test piece of × GL 30 mm was used so that the molten metal, the heat-affected zone, and the base metal would enter the parallel part. Creep test is 650 ℃
The maximum time was about 10,000 hours.
【0051】650 ℃での最長クリープ破断材について、
溶接熱影響部と母材との界面から剪断的な破壊をした試
験片で、伸びが3%以下の場合をTypeIVクラッキングが
あったものとした。硬さ測定は、母材および後熱処理し
た溶接継手断面についてビッカース10kgf荷重で行っ
た。Regarding the longest creep rupture material at 650 ° C.,
A test piece that was sheared from the interface between the heat-affected zone and the base metal and had an elongation of 3% or less was considered to have Type IV cracking. The hardness was measured with a Vickers load of 10 kgf on the base material and the post-heat-treated welded joint cross section.
【0052】表2に各測定結果をまとめて示す。なお、
溶接熱影響部の軟化傾向の評価は、溶接熱影響部の最も
軟化した部分の硬さと母材硬さとの差で行った。Table 2 collectively shows the measurement results. In addition,
The softening tendency of the welding heat affected zone was evaluated by the difference between the hardness of the softest part of the welding heat affected zone and the hardness of the base material.
【0053】母材の常温引張特性では、表2に示すよう
に本発明鋼は比較鋼に比べて伸びが20%以上とやや高め
である。With respect to the normal temperature tensile properties of the base material, as shown in Table 2, the steel of the present invention has an elongation of 20% or more, which is slightly higher than that of the comparative steel.
【0054】溶接継手の最軟化部と母材の硬さとの差
が、符号A3鋼ではHv45と大きく、Cuを添加した符号
A5〜A12鋼のいずれもがHv50以上の大きな硬さ低下
を示しているのに対し、本発明鋼の符号B1〜B25鋼は
いずれもHv40以下と小さい。The difference between the softest part of the welded joint and the hardness of the base material was as large as Hv45 for the A3 steel, and all of the A5 to A12 steels containing Cu showed a large decrease in hardness of Hv50 or more. In contrast, all of the steels of the present invention, B1 to B25, have small Hv40 or less.
【0055】すなわち、本発明鋼では溶接熱影響部の軟
化が著しく抑制されている。That is, in the steel of the present invention, the softening of the weld heat affected zone is remarkably suppressed.
【0056】表2の溶接継手の 650℃×104 時間クリー
プ破断強度をみると、符号B1〜B25の本発明鋼は 8.2
〜9.5 kgf/mm2 とすぐれたクリープ破断強度であるのに
対し、符号A3〜A12の比較鋼はいずれも5.2 kgf/mm2
以下と低い。なお、比較鋼の符号A1、A2はV、Nbを
含有せず、母材強度が低くクリープ破断強度もそれぞれ
3.3 kgf/mm2、3.6 kgf/mm2 と低い。Looking at the creep rupture strength of the welded joint of Table 2 at 650 ° C. × 10 4 hours, the steels of the present invention having the symbols B1 to B25 are 8.2.
It has excellent creep rupture strength of up to 9.5 kgf / mm 2 , whereas the comparative steels with codes A3 to A12 are all 5.2 kgf / mm 2
Low as below. The reference steels A1 and A2 of the comparative steels do not contain V and Nb, have low base metal strength and creep rupture strength.
It is as low as 3.3 kgf / mm 2 and 3.6 kgf / mm 2 .
【0057】さらにクリープ破断材の調査により、本発
明鋼のいずれにもTypeIVクラッキングを生じないことが
明らかとなった。Further investigation of creep rupture materials revealed that none of the inventive steels produced Type IV cracking.
【0058】[0058]
【表1(1)】 [Table 1 (1)]
【0059】[0059]
【表1(2)】 [Table 1 (2)]
【0060】[0060]
【表1(3)】 [Table 1 (3)]
【0061】[0061]
【表2(1)】 [Table 2 (1)]
【0062】[0062]
【表2(2)】 [Table 2 (2)]
【0063】[0063]
【表2(3)】 [Table 2 (3)]
【0064】[0064]
【発明の効果】本発明の高Crフェライト鋼は、溶接継手
の熱影響部の強度低下が小さく、従来鋼より継手のクリ
ープ破断強度に優れ、TypeIVクラッキングの発生もな
い。即ち、本発明鋼は、従来の高Crフェライト耐熱鋼の
難点である溶接継手の熱影響部における強度低下の小さ
い高Crフェライト鋼としてボイラー、化学工業、原子力
などの分野で耐熱耐圧部材として、管、板、鍛造、圧延
材等に広く利用できるものである。EFFECTS OF THE INVENTION The high Cr ferritic steel of the present invention causes less decrease in strength of the heat-affected zone of the welded joint, has better creep rupture strength of the joint than conventional steel, and does not cause Type IV cracking. That is, the steel of the present invention, as a high-Cr ferritic steel having a small strength reduction in the heat-affected zone of the welded joint, which is a drawback of conventional high-Cr ferritic heat-resistant steel, as a heat-resistant pressure-resistant member in the fields of boilers, chemical industry, nuclear power, etc. It can be widely used for sheet, plate, forging, rolled material, etc.
【0065】[0065]
Claims (5)
以下、Mn: 0.1〜1.5 %、Ni:0.05〜1.0 %、Cr:8〜
14%、Mo:0.01〜3%、V: 0.1〜0.3 %、Nb:0.01〜
0.2%、N: 0.001〜0.1 %、Al: 0.001〜0.05%、C
u: 0.4〜3.5 %を含み、残部は鉄および不可避的不純
物からなり、不純物としてのO (固溶酸素) が0.015%
以下である溶接熱影響部の強度低下の小さい高クロムフ
ェライト耐熱鋼。1. C: 0.03 to 0.15% by weight, Si: 0.7% by weight
Below, Mn: 0.1-1.5%, Ni: 0.05-1.0%, Cr: 8-
14%, Mo: 0.01-3%, V: 0.1-0.3%, Nb: 0.01-
0.2%, N: 0.001-0.1%, Al: 0.001-0.05%, C
u: 0.4-3.5%, balance is iron and unavoidable impurities, and O (solid solution oxygen) as impurities is 0.015%
The high-chromium ferritic heat-resistant steel with less strength reduction in the weld heat-affected zone as follows.
のBを含有する請求項1の高クロムフェライト耐熱鋼。2. Further, as an alloy component, 0.0001 to 0.02% by weight
The high chromium ferritic heat-resistant steel according to claim 1, which contains B.
を含有する請求項1または2の高クロムフェライト耐熱
鋼。3. Further, as an alloy component, W of less than 0.5% by weight.
The high chromium ferritic heat resistant steel according to claim 1 or 2, containing.
のMgを含有する請求項1、2または3の高強度高クロム
フェライト耐熱鋼。4. Further, as an alloy component, 0.0001 to 0.1% by weight
The high-strength, high-chromium ferritic heat-resistant steel according to claim 1, 2 or 3, which contains Mg.
重量%のLa、Ce、Ca、Zr、Ti、YおよびTaからなる群か
ら選択した1種以上を含有する請求項1、2、3または
4の高クロムフェライト耐熱鋼。5. Further, as an alloy component, 0.01 to 0.2, respectively.
The high chromium ferrite heat-resistant steel according to claim 1, 2, 3 or 4, which contains at least one selected from the group consisting of La, Ce, Ca, Zr, Ti, Y and Ta in a weight percentage.
Priority Applications (1)
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JP20164491A JP3237137B2 (en) | 1991-08-12 | 1991-08-12 | High chromium ferritic heat-resistant steel with small decrease in strength of weld heat affected zone |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP20164491A JP3237137B2 (en) | 1991-08-12 | 1991-08-12 | High chromium ferritic heat-resistant steel with small decrease in strength of weld heat affected zone |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH0543986A true JPH0543986A (en) | 1993-02-23 |
JP3237137B2 JP3237137B2 (en) | 2001-12-10 |
Family
ID=16444506
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Application Number | Title | Priority Date | Filing Date |
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JP20164491A Expired - Lifetime JP3237137B2 (en) | 1991-08-12 | 1991-08-12 | High chromium ferritic heat-resistant steel with small decrease in strength of weld heat affected zone |
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Cited By (7)
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WO1996014443A1 (en) * | 1994-11-04 | 1996-05-17 | Nippon Steel Corporation | High-strength ferritic heat-resistant steel and process for producing the same |
WO2002090610A1 (en) * | 2001-05-09 | 2002-11-14 | Sumitomo Metal Industries, Ltd. | Ferritic heat-resistant steel |
WO2004087979A1 (en) | 2003-03-31 | 2004-10-14 | National Institute For Materials Science | Welded joint of tempered martensite based heat-resistant steel |
JP2008291363A (en) * | 2007-04-27 | 2008-12-04 | Nippon Steel Corp | Ferritic heat resistant steel having excellent creep property in weld heat-affected zone, and heat resistant structure |
JP2008291360A (en) * | 2007-04-25 | 2008-12-04 | Nippon Steel Corp | Ferritic heat resistant steel having excellent creep property in welded heat-affected zone, and heat resistant structure |
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Cited By (10)
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WO1996014443A1 (en) * | 1994-11-04 | 1996-05-17 | Nippon Steel Corporation | High-strength ferritic heat-resistant steel and process for producing the same |
US5766376A (en) * | 1994-11-04 | 1998-06-16 | Nippon Steel Corporation | High-strength ferritic heat-resistant steel and method of producing the same |
CN1061700C (en) * | 1994-11-04 | 2001-02-07 | 新日本制铁株式会社 | High-strength ferritic heat-resistant steel and process for producing the same |
WO2002090610A1 (en) * | 2001-05-09 | 2002-11-14 | Sumitomo Metal Industries, Ltd. | Ferritic heat-resistant steel |
US6712913B2 (en) | 2001-05-09 | 2004-03-30 | Sumitomo Metal Industries, Ltd. | Ferritic heat-resisting steel |
WO2004087979A1 (en) | 2003-03-31 | 2004-10-14 | National Institute For Materials Science | Welded joint of tempered martensite based heat-resistant steel |
US9005520B2 (en) | 2006-06-09 | 2015-04-14 | V & M France | Steel compositions for special uses |
JP2008291360A (en) * | 2007-04-25 | 2008-12-04 | Nippon Steel Corp | Ferritic heat resistant steel having excellent creep property in welded heat-affected zone, and heat resistant structure |
JP2008291363A (en) * | 2007-04-27 | 2008-12-04 | Nippon Steel Corp | Ferritic heat resistant steel having excellent creep property in weld heat-affected zone, and heat resistant structure |
CN103540859A (en) * | 2013-10-31 | 2014-01-29 | 万宝力不锈钢制品(东莞)有限公司 | High heat-resistant stainless steel coffee pot material and preparation method thereof |
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