JPH1088274A - High strength heat resistant steel and its production - Google Patents

High strength heat resistant steel and its production

Info

Publication number
JPH1088274A
JPH1088274A JP23960096A JP23960096A JPH1088274A JP H1088274 A JPH1088274 A JP H1088274A JP 23960096 A JP23960096 A JP 23960096A JP 23960096 A JP23960096 A JP 23960096A JP H1088274 A JPH1088274 A JP H1088274A
Authority
JP
Japan
Prior art keywords
steel
temperature
strength
toughness
resistant steel
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.)
Pending
Application number
JP23960096A
Other languages
Japanese (ja)
Inventor
Seinosuke Yano
清之助 矢野
Yasushi Moriyama
康 森山
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Japan Casting and Forging Corp
Original Assignee
Japan Casting and Forging Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Japan Casting and Forging Corp filed Critical Japan Casting and Forging Corp
Priority to JP23960096A priority Critical patent/JPH1088274A/en
Publication of JPH1088274A publication Critical patent/JPH1088274A/en
Pending legal-status Critical Current

Links

Abstract

PROBLEM TO BE SOLVED: To obtain a high strength heat resistant steel increased in toughness at ordinary temp., excellent in high temp. strength, and having economical efficiency by specifying a composition consisting of C, Si, Mn, Ni, Cr, Mo, V, N, Al, O, and Fe. SOLUTION: This steel is a high strength heat resistant steel which has a composition consisting of, by weight, 0.15-0.25% C, <=0.2% Si, <=1.5% Mn, <=1.5% Ni, 2.8-4.5% Cr, 0.5-2.O% Mo, 0.10-0.20% V, 0.008-0.025% N, <=0.03% Al, <=0.0030% O, and the balance Fe with inevitable impurities and further containing, if necessary, 0.5-1.5% Cu and/or 0.001-0.007% Ca and can be suitably used for disk, rotor material, etc., for thick and large-diameter gas or steam turbine. This heat resistant steel can be obtained by subjecting an ingot or slab of steel with the above composition to heating up to >=1000 deg.C and to hot forging, finishing the working at >=650 deg.C steel slab central temp., applying cooling, performing reheating one or more times at a temp. in the range between (Ac3 transformation point + 50 deg.C) and 1,100 deg.C, and then subjecting the steel to hardening and further to tempering at <=Ac1 one or more times.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】この発明は、常温靭性が高く
高温強度に優れた耐熱鋼およびその製造方法に関するも
のであり、特に、発電用ガス・タービンや蒸気タービン
のディスク、ロータなどに使用される改良された耐熱鋼
およびその製造方法に係わり、さらに一般化学プラント
用耐熱鋼としても利用できるものである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant steel having high room-temperature toughness and excellent high-temperature strength, and a method for producing the same. Particularly, the invention is used for disks and rotors of power generation gas turbines and steam turbines. The present invention relates to an improved heat-resistant steel and a method for producing the same, and can also be used as a heat-resistant steel for general chemical plants.

【0002】[0002]

【従来の技術】従来、この分野での鋼材料には高温での
引張強さ、耐クリープ・ラプチャー性などの耐熱性と耐
酸化性を重視して含Cr鋼が使用され、その改良に関す
る種々の発明が提供されている。特に本発明が対象とす
る分野では12%Cr系にCo:6%を添加した耐熱鋼
が広く使用されているが、希少資源であるCoを6%も
含有するため甚だ高価な鋼材とならざるを得ない。その
ため特開昭56−13466号公報には、その経済性と
靭性の改善を図った非Co系10〜12.5%Cr鋼が
開示されている。
2. Description of the Related Art Conventionally, Cr-containing steel has been used as a steel material in this field with an emphasis on heat resistance such as tensile strength at high temperatures, resistance to creep and rupture, and oxidation resistance. Invention is provided. In particular, in the field targeted by the present invention, heat-resistant steel in which Co: 6% is added to 12% Cr-based steel is widely used, but it contains 6% of Co, which is a scarce resource, so that it is extremely expensive steel. Not get. For this reason, Japanese Patent Application Laid-Open No. 56-13466 discloses a non-Co-based 10 to 12.5% Cr steel in which the economy and toughness are improved.

【0003】またそのほかに、Cr含有量を低減した耐
熱鋼には例えば特開平2−20440号公報に開示され
た高温強度と靭性を考慮した4〜6%Cr鋼、特開昭6
0−245772号公報に開示された高低圧一体型蒸気
タービンロータ用の1.8〜2.8%Cr含有耐熱鋼、
特開平1−316441号公報に開示された靭性と曲げ
加工性を配慮した0.4〜1.4%Cr含有耐熱鋼など
がある。
[0003] In addition, a heat-resistant steel having a reduced Cr content is, for example, a 4-6% Cr steel in consideration of high temperature strength and toughness disclosed in Japanese Patent Application Laid-Open No. 2-20440.
No. 0-245772, a heat-resistant steel containing 1.8 to 2.8% Cr for a high-low pressure integrated steam turbine rotor,
There is a heat-resistant steel containing 0.4 to 1.4% Cr which considers toughness and bendability disclosed in JP-A-1-316441.

【0004】[0004]

【発明が解決しようとする課題】前述したように、従来
ガスタービン用ディスク材には、12%Cr−6%Co
鋼が使用されているが、経済性と靭性とに対して改善が
強く求められてきた。前記の公報に代表される従来鋼に
は改善の意図が見られるが、経済性を含めて考慮すると
それぞれ難点がある。すなわち、特開昭56−1346
6号公報は高価なCoを含有せずに、強度・靭性は目標
値を満足するがCrは従来と同じ10〜12.5%であ
り、しかもこのような強度と靭性を確保するための焼き
入れ温度は、1150℃という高温に設定されており、
その結果、結晶粒度が粗大化して靭性を害するばかりか
熱処理炉への負担も大きくなるとい問題があり、結局経
済性を著しく改善することは難しい。次に、特開平2−
20440号公報はCr含有量は4.0〜6.0%に低
減しているが、公報に記載の文献に記述されているよう
に、高いクリープ破断強度を得るために1100℃以上
の高温焼きならしが必要とされ、やはり熱処理炉への負
担は大きなものがあるほか、成分上の制約から強度のレ
ベルは高々60kgf/mm2 級で目標のレベルに対して低
く、12%Cr−6%Co鋼および大型高強度ロータ材
の代替には成りえない。特開昭60−245772号公
報は1.8〜2.8%Cr含有鋼で、強度・靭性、耐熱
性のいづれもロータ材として企図するレベルに最も近い
が、中心部では強度または靭性が低く、目的の材質を得
るには強度−靭性バランスが不適である。特開平1−3
16441号公報は、0.4〜1.4%Cr鋼であるが
常温および高温強度が目標のレベルに対して不足してい
る。
As described above, conventional disk materials for gas turbines include 12% Cr-6% Co.
Although steel is used, improvements in economy and toughness have been strongly sought. Although there is an intention to improve conventional steels represented by the above-mentioned publications, there are drawbacks in consideration of economy and the like. That is, JP-A-56-1346
No. 6 does not contain expensive Co, and satisfies the target values of strength and toughness, but Cr is 10 to 12.5%, which is the same as the conventional one, and furthermore, firing for securing such strength and toughness is performed. The charging temperature is set as high as 1150 ° C,
As a result, there is a problem that not only the crystal grain size becomes coarse and the toughness is impaired, but also the burden on the heat treatment furnace increases, and it is difficult to remarkably improve the economic efficiency after all. Next, JP-A-2-
In the publication No. 20440, the Cr content is reduced to 4.0 to 6.0%, but as described in the literature described in the publication, high-temperature baking at 1100 ° C. or more is performed to obtain high creep rupture strength. break is required, also in addition to the burden on the heat treatment furnace is large, lower than the level of the target at most 60 kgf / mm 2 grade-level intensity from restrictions on components, 12% Cr-6% It cannot be a substitute for Co steel and large high-strength rotor materials. Japanese Patent Application Laid-Open No. 60-245772 discloses a steel containing 1.8 to 2.8% Cr, which has strength, toughness, and heat resistance closest to the level intended for a rotor material, but has low strength or toughness at the center. In order to obtain the desired material, the strength-toughness balance is inappropriate. JP-A 1-3
Japanese Patent No. 16441 discloses 0.4 to 1.4% Cr steel, but the room temperature and high temperature strengths are insufficient with respect to target levels.

【0005】本発明は、今後ますます需要が増すと考え
られる厚手大径の発電用ガス・タービンや蒸気タービン
のディスク、ロータなどに対して、従来にない経済性と
強靭耐熱性を有する鋼材とその製造法を提供するもので
ある。すなわち具体的には、高価なCoを含有せずに常
温引張強度102kgf/mm2 以上、切り欠き引張強度15
8kgf/mm2 以上、負荷応力53kgf/mm2 で482℃×1
00時間保定後の塑性歪み量が0.15%以下の高温特
性を有し、しかも常温衝撃値2.1 kgf・m以上、遷移
温度40℃以下の高靭性耐熱鋼を提供するものである。
さらにまた、タービン・ロータ材として常温引張強度8
5kgf/mm2 以上、400℃での降伏強度(または0.2
%耐力)65kgf/mm2 以上の高強度と常温衝撃値3.5
kgf・m以上、遷移温度40℃以下の靭性を有し、さら
に400℃以上の高温での耐クリープ性を持つような強
靭耐熱鋼およびその製造法を提供することを目的とする
ものである。
The present invention relates to a steel material having unprecedented economic efficiency and tough heat resistance for a disk and a rotor of a thick and large-diameter power generating gas turbine or a steam turbine, which is expected to be increasingly demanded in the future. The method of manufacture is provided. That is, specifically, without containing expensive Co, a room temperature tensile strength of 102 kgf / mm 2 or more, a notch tensile strength of 15 kgf / mm 2 or more.
8 kgf / mm 2 or more, the load stress 53kgf / mm 2 at 482 ° C. × 1
An object of the present invention is to provide a high-toughness heat-resistant steel having high-temperature properties in which the amount of plastic strain after holding for 00 hours is 0.15% or less, and a normal temperature impact value of 2.1 kgf · m or more and a transition temperature of 40 ° C. or less.
Further, as a turbine rotor material, a room temperature tensile strength of 8
5 kgf / mm 2 or more, yield strength at 400 ° C (or 0.2
% Proof strength) 65kgf / mm 2 or more high strength and normal temperature impact value 3.5
It is an object of the present invention to provide a tough heat-resistant steel having a toughness of not less than kgf · m and a transition temperature of not more than 40 ° C., and also having a creep resistance at a high temperature of not less than 400 ° C. and a method for producing the same.

【0006】[0006]

【課題を解決するための手段】本発明者らは上記の目的
を達成するために鋼を構成する化学成分と熱処理条件と
について詳細な検討を行った。その結果、Cr含有量と
オーステナイト化温度とは焼入れ組織を通して鋼の強度
に密接に関係し、Cr含有量が9%を超えると1100
℃よりも高い温度に加熱しなければ高い強度が得られな
いこと、言い換えれば焼き戻し条件が同じ時、Cr含有
量が9%よりも低ければ低い程、低いオーステナイト化
温度で高い強度が得られることを知見した。さらに、C
uを0.5〜1.5%含有すると高強度がさらに得やす
くなり、また焼戻し条件による強度の変化が小さくなる
ことなど極厚の鋼製品の質量効果を低減し、熱処理後の
組織を細粒にして材質を安定化する上で重要な事実を発
見した。さらにまたNbについてこれを添加すると鋼塊
の偏析帯にNbの炭・窒化物が大きく析出し、その後の
鍛造加熱や鍛造中に容易に分解せず結果的に成品の靭性
を著しく低下せしめるために、含有させないのが望まし
いことが分かった。
Means for Solving the Problems In order to achieve the above object, the present inventors have conducted a detailed study on the chemical components constituting steel and the heat treatment conditions. As a result, the Cr content and the austenitizing temperature are closely related to the strength of the steel through the quenched structure, and 1100 when the Cr content exceeds 9%.
High strength cannot be obtained unless heated to a temperature higher than ℃, in other words, when the tempering conditions are the same, the lower the Cr content is less than 9%, the higher the strength is obtained at a lower austenitizing temperature. I found that. Further, C
When the content of u is 0.5 to 1.5%, high strength can be more easily obtained, and the mass effect of an extremely thick steel product such as a change in strength due to tempering conditions can be reduced. We found an important fact to stabilize the material by granulation. In addition, when Nb is added, Nb carbon / nitride precipitates largely in the segregation zone of the steel ingot, and is not easily decomposed during subsequent forging heating or forging, and as a result, the toughness of the product is significantly reduced. It was found that it was desirable not to contain them.

【0007】本発明は、これらの新事実に基づいて構成
されたものでC,Si,Mn,Cu,Ni,Cr,M
o,V,N,Alを主成分とし、焼入れ熱処理によって
目的とする鋼製品にマルテンサイト−ベイナイト混合組
織を生成せしめ、同時に焼入れ変態時の変態転位上にV
の炭・窒化物を微細に析出させ、その後焼戻しして組織
の回復と析出物の析出、整合性と量を調節することを特
徴とする。この過程において結晶組織・粒度、析出物の
分布・量・サイズを適正に制御するために、鋼成分と熱
処理条件を規制する。
The present invention has been made based on these new facts, and is based on C, Si, Mn, Cu, Ni, Cr, M
o, V, N, Al as a main component, a martensite-bainite mixed structure is formed in a target steel product by quenching heat treatment, and at the same time, V is formed on the transformation dislocation during quenching transformation.
Is characterized by finely depositing carbon / nitride, and then tempering to control the structure recovery, precipitate precipitation, consistency and amount. In this process, steel components and heat treatment conditions are regulated in order to properly control the crystal structure, grain size, and distribution, amount, and size of precipitates.

【0008】すなわち本発明は以下の構成を要旨とす
る。重量%で C :0.15〜0.25%、 Si≦0.2%、 Mn≦1.5%、 Ni≦1.5%、 Cr:2.8〜4.5%、 Mo:0.5〜2.0%、 V :0.10〜0.20%、 N :0.008〜0.025%、 Al≦0.03%、 O ≦0.0030%、 必要に応じて Cu:0.5%〜1.5%、 Ca:0.001%〜0.007% の一種または二種以上を含有し、残部がFeおよび不可
避的不純物からなることを特徴とする常温靭性が高く高
温強度に優れた耐熱鋼であり、また、前記耐熱鋼はガス
・タービン用または蒸気タービン用のディスクまたはロ
ータに用いられ、かつ100kgf/mm2 以上または85kg
f/mm2 以上の常温での引張強度を有することを特徴とす
る。
That is, the present invention has the following constitution. C: 0.15% to 0.25%, Si ≦ 0.2%, Mn ≦ 1.5%, Ni ≦ 1.5%, Cr: 2.8 to 4.5%, Mo: 0% by weight. 5 to 2.0%, V: 0.10 to 0.20%, N: 0.008 to 0.025%, Al ≦ 0.03%, O ≦ 0.0030%, if necessary, Cu: 0 0.5% to 1.5%, Ca: 0.001% to 0.007%, and the balance consists of Fe and inevitable impurities. The heat-resistant steel is used for a disc or a rotor for a gas turbine or a steam turbine, and is 100 kgf / mm 2 or more or 85 kg.
It has a tensile strength at room temperature of f / mm 2 or more.

【0009】さらに本発明は、上記の鋼成分からなる鋼
塊または鋼片を1000℃以上の温度域に加熱し、つい
で熱間鍛造加工を行い、該加工を鋼片の中心温度が65
0℃以上の温度範囲で終了し、冷却後、Ac3 変態点+
50℃以上、1100℃以下の温度に1回以上再加熱し
た後焼入れし、Ac1 以下の温度で1回以上焼戻しをす
ることを特徴とする常温靭性が高く高温強度に優れた耐
熱鋼の製造方法である。
Further, according to the present invention, a steel ingot or a steel slab composed of the above-mentioned steel component is heated to a temperature range of 1000 ° C. or more, and then hot forging is performed.
Finish at a temperature range of 0 ° C. or higher, and after cooling, the Ac 3 transformation point +
Production of heat-resistant steel with high room temperature toughness and excellent high-temperature strength characterized by quenching after reheating to a temperature of 50 ° C. or more and 1100 ° C. or less once and then quenching at a temperature of Ac 1 or less. Is the way.

【0010】[0010]

【発明の実施の形態】次に本発明の成分を限定した理由
を説明する。Cは、常温および高温の強度を確保する上
で重要な元素である。特に厚手大径の発電用スチーム・
タービンやガス・タービンのディスク、ロータなどに対
して、焼入れ速度の広い範囲にわたってマルテンサイト
−ベイナイト混合組織を安定して得る必要があり、その
ためには0.15%以上を要し、一方、過剰な添加は炭
化物の凝集と粗大化を生じ高温強度の低下を招き、また
著しく靭性を劣化せしめるため上限を0.25%とし
た。
Next, the reasons for limiting the components of the present invention will be described. C is an important element for ensuring the strength at room temperature and high temperature. Especially for thick and large diameter steam for power generation
It is necessary to stably obtain a martensite-bainite mixed structure over a wide range of quenching speeds for turbines, gas turbine disks, rotors, and the like. An excessive addition causes carbide agglomeration and coarsening to cause a decrease in high-temperature strength, and also significantly deteriorates toughness, so the upper limit is made 0.25%.

【0011】Siは、本発明鋼においては後述の理由で
Alの添加を制限しているので脱酸剤として用いるが、
高温使用中に焼き戻し脆性を生じやすくするのでその上
限を0.2%に限定する。Mnは、Siと同じように脱
酸剤として用いるほかSを固定して結晶粒界の強度を上
昇させる。しかし、多量に添加すると焼き戻し脆性を助
長するので上限を1.5%に規制した。
Si is used as a deoxidizing agent in the steel of the present invention because the addition of Al is restricted for the reasons described below.
The upper limit is limited to 0.2% because tempering embrittlement is likely to occur during high temperature use. Like Mn, Mn is used as a deoxidizing agent, and also fixes S to increase the strength of crystal grain boundaries. However, when added in a large amount, tempering embrittlement is promoted, so the upper limit was regulated to 1.5%.

【0012】Niは、交叉辷りを容易にして靭性を向上
させる効果があるが、過剰に添加すると焼き戻し脆性感
受性を増大させるので1.5%以下とした。Crは、強
固な酸化膜を形成して耐酸化性を高めるが、多量に添加
するとクリープ破断強度を低下させるほか高温焼き戻し
で反って強度が低下するため目的の強度と靭性を確保す
るための最も適正な範囲として下限を2.8%、上限を
4.5%とした。
Ni has the effect of facilitating cross-slip and improving toughness. However, if added excessively, it increases the temper brittleness susceptibility. Cr forms a strong oxide film and enhances oxidation resistance, but when added in a large amount, it reduces creep rupture strength and warps at high temperature tempering to decrease the strength, so that the desired strength and toughness are secured. As the most appropriate ranges, the lower limit was 2.8% and the upper limit was 4.5%.

【0013】Moは、炭化物を形成し、あるいは原子空
孔を捕捉して転位の上昇運動を妨げ高温まで強度を保つ
上で重要な働きをするが、その効果は0.5%未満では
十分でなく、また2.0%超では飽和しかつ靭性を阻害
するので、その範囲を0.5〜2.0%とした。Vは、
炭化物、窒化物を形成して鋼の強化に寄与するが、特に
本発明においては、一般鋼材よりも多量に添加したNに
よりオーステナイト(γ)域でVNが析出しγ粒を細粒
化するほか、変態時に変態界面に析出してγ/α結晶粒
変換比を大きくし鋼組織を一層細粒化し強度・靭性を向
上させ、かつ高温強度・クリープ破断強度を著しく高め
る。その効果は0.05〜0.20%で十分に現われ、
それ以上の添加は靭性を低下させる。
Mo plays an important role in forming carbides or trapping vacancies to prevent dislocation rising motion and maintain strength at high temperatures, but its effect is less than 0.5%. However, if it exceeds 2.0%, it saturates and impairs toughness, so its range is set to 0.5 to 2.0%. V is
Contributes to the strengthening of steel by forming carbides and nitrides. In particular, in the present invention, VN precipitates in the austenite (γ) region due to N added in a larger amount than ordinary steel materials, and the γ grains are refined. At the time of transformation, it precipitates at the transformation interface to increase the γ / α crystal grain conversion ratio, further refine the steel structure, improve strength and toughness, and significantly increase high temperature strength and creep rupture strength. The effect appears sufficiently at 0.05 to 0.20%,
Further addition decreases the toughness.

【0014】Nは、上記の効果をコントロールする上で
重要な元素であり、その量は上記V量に対応して0.0
080〜0.250%が必要となる。Alは、脱酸剤と
して使用するが、固溶Alが過剰に残存するとNとの化
合が増加し、本発明鋼の特徴であるVNの析出量を低減
させるため、0.030%を上限とする。Oは、鋼中に
僅か固溶するが、その殆どはSi,Al,Crなどと酸
化物を形成し靭性を著しく損ねる。特にまた、本発明鋼
のような高強度鋼の場合使用中に疲労亀裂の起点となる
可能性が高い。これらの現象を防止するには0.003
0%以下にすることが必要である。
N is an important element for controlling the above-mentioned effects, and the amount of N is 0.0
080-0.250% is required. Al is used as a deoxidizing agent. However, if solid solution Al remains excessively, compounding with N increases and the amount of precipitation of VN, which is a feature of the steel of the present invention, is reduced. I do. O slightly forms a solid solution in steel, but most of them form oxides with Si, Al, Cr and the like, and significantly impair the toughness. In particular, in the case of a high-strength steel such as the steel of the present invention, there is a high possibility of becoming a starting point of a fatigue crack during use. 0.003 to prevent these phenomena
It is necessary to make it 0% or less.

【0015】以上が本発明鋼の基本成分であるが、常温
および高温強度、靭性、クリープ破断強度の向上の目的
で、Cu,Caの一種または二種以上を含有することが
できる。Cuは、常温および高温強度の向上に有効で、
本発明の特に高強度を得る目的のためには重要な元素で
あり、高いクリープ破断強度と靭性を両立させる場合に
は効果があるが熱間加工成形での割れ発生を考慮して添
加の範囲を0.5%〜1.5%とした。Caは、脱酸剤
としての効果と硫化物(MnS)を細分化し、母材の延
性、靭性を向上させ、異方性を抑制する効果を持つ。し
かしながら、0.001%未満では効果がなく、0.0
07%を超えると粗大なCa硫化酸化物を生成し、延
性、靭性を低下させるので0.001〜0.007%と
した。
The above are the basic components of the steel of the present invention, but one or more of Cu and Ca can be contained for the purpose of improving the strength at room temperature and high temperature, the toughness and the creep rupture strength. Cu is effective for improving room temperature and high temperature strength,
It is an important element for the purpose of obtaining particularly high strength of the present invention, and it is effective when achieving both high creep rupture strength and toughness, but the range of addition in consideration of cracking during hot working Was set to 0.5% to 1.5%. Ca has an effect as a deoxidizing agent and an effect of subdividing sulfide (MnS), improving ductility and toughness of a base material, and suppressing anisotropy. However, less than 0.001% has no effect,
If it exceeds 07%, coarse Ca sulfide oxides are generated, and ductility and toughness are reduced.

【0016】次に本発明の製造方法について述べる。本
発明鋼の製鋼炉は電気炉、転炉など現用の溶解炉のいず
れによってもよく特に規定しない。また、脱ガス、取鍋
精錬技術やESR、VARなどの再溶解精錬を適用する
こともできる。
Next, the manufacturing method of the present invention will be described. The steelmaking furnace for the steel of the present invention may be any of the current melting furnaces such as an electric furnace and a converter, and is not particularly limited. In addition, degassing, ladle refining technology, and remelting and refining such as ESR and VAR can also be applied.

【0017】このようにして溶製され、造塊された鋼
塊、あるいは造塊−分塊または連続鋳造などによって鋼
片となった本発明鋼を鍛造加工するが、そのときの再加
熱温度は1100〜1300℃の温度域に規制する。高
温強度を確保するのに重要なV,Moの添加効果を最大
にするために、これらの元素を熱間鍛造前の加熱時に十
分に固溶させる必要から、再加熱温度の下限を1100
℃とし、その上限は加熱炉の性能、経済性から1300
℃とする。
[0017] The steel of the present invention, which has been made into a steel ingot by ingot and ingot or ingot-bulking or continuous casting in this way, is forged, but the reheating temperature at that time is as follows. It is restricted to a temperature range of 1100 to 1300 ° C. In order to maximize the effect of adding V and Mo, which are important for securing high-temperature strength, these elements must be fully dissolved in the heating before hot forging, so the lower limit of the reheating temperature is 1100.
° C, and the upper limit is 1300 from the performance and economy of the heating furnace.
° C.

【0018】熱間鍛造における終了温度は中心温度で6
50℃以上とする。好ましい温度範囲は800〜105
0℃である。最終鍛造温度が650℃よりも低下する
と、導入された転位上へのVNの析出が急増し、急激な
強度上昇が生じると共に熱間加工性が低下し割れが発生
する恐れがあるためである。したがって、加工時間が長
くなって鋼片の加工終了温度が650℃以下に低下する
場合には、再度加熱炉に鋼片を装入し再加熱を行う。
The end temperature in hot forging is 6 at the center temperature.
50 ° C. or higher. The preferred temperature range is 800 to 105
0 ° C. If the final forging temperature is lower than 650 ° C., the precipitation of VN on the introduced dislocations will increase rapidly, causing a rapid increase in strength and a decrease in hot workability, which may cause cracking. Therefore, when the processing time becomes long and the processing end temperature of the steel slab falls to 650 ° C. or lower, the steel slab is charged again into the heating furnace and reheated.

【0019】本発明では、焼入れ焼戻し調質熱処理を基
本熱処理とする。焼入れ処理のためのオーステナイト化
温度は、Ac3 変態点+50℃以上、1100℃以下、
好ましくは、熱処理コストおよび常温ならびに高温強度
と靭性とのバランスから、900〜1050℃範囲で1
回以上行う。本発明鋼では焼き入れ温度の低温側では靭
性は良好であるが強度が不足し、高温側では強度は良好
になるが靭性が不足する傾向が強い。焼入れは、水冷、
油冷、強制空冷のいずれでも良い。
In the present invention, the quenching and tempering tempering heat treatment is defined as the basic heat treatment. The austenitizing temperature for the quenching treatment is from the Ac 3 transformation point + 50 ° C to 1100 ° C,
Preferably, the temperature is in the range of 900 to 1050 ° C. in consideration of the heat treatment cost and the balance between normal temperature and high temperature strength and toughness.
Do more than once. In the steel of the present invention, the toughness is good but the strength is insufficient at a low quenching temperature side, and the strength is good at a high temperature side, but the toughness tends to be insufficient. Quenching is water-cooled,
Either oil cooling or forced air cooling may be used.

【0020】焼戻し処理は、Ac1 点以下の温度、好ま
しくは、600〜700℃で常温引張強度が目標の強度
・靭性となるように焼戻し温度と時間を選定する。特に
12%Cr−6%Co鋼の代替とする場合は、常温強度
が102kgf/mm2 以上となるように上記温度範囲で焼戻
し時間を選定する。これによって、従来の耐熱鋼に比
べ、低成分、低温短時間熱処理、高性能を特徴とする新
耐熱鋼を低コストで製造することができる。
In the tempering treatment, the tempering temperature and time are selected so that the room-temperature tensile strength attains the target strength and toughness at a temperature of not more than one point Ac, preferably at 600 to 700 ° C. In particular, when substituting for 12% Cr-6% Co steel, the tempering time is selected within the above temperature range so that the room temperature strength is 102 kgf / mm 2 or more. As a result, a new heat-resistant steel characterized by low components, low-temperature short-time heat treatment, and high performance can be manufactured at lower cost than conventional heat-resistant steel.

【0021】かくして本発明により、常温引張強度10
2kgf/mm2 以上、切り欠き引張強度158kgf/mm2
上、負荷応力53kgf/mm2 で482℃×100時間保定
後の塑性歪み量が0.15%以下の高温特性を有し、し
かも常温衝撃値2.1 kgf・m以上、遷移温度40℃以
下の高靭性耐熱鋼を得ることができる。さらにタービン
・ロータ材として常温引張強度85kgf/mm2 以上、40
0℃での降伏強度(または0.2%耐力)65kgf/mm2
以上の高強度と常温衝撃値3.5 kgf・m以上、遷移温
度40℃以下の靭性を有し、さらに400℃以上の高温
での耐クリープ性を持つような強靭耐熱鋼が得られる。
Thus, according to the present invention, a room temperature tensile strength of 10
2 kgf / mm 2 or more, notch tensile strength 158kgf / mm 2 or more, plastic strain amount after loading stress 53kgf / mm 2 at 482 ° C. × 100 hours retention has high temperature characteristics of 0.15% or less, yet cold shock A high toughness heat-resistant steel having a value of 2.1 kgf · m or more and a transition temperature of 40 ° C. or less can be obtained. Further roomtemperature tensile strength 85 kgf / mm 2 or more as a turbine rotor material, 40
Yield strength at 0 ° C (or 0.2% proof stress) 65kgf / mm 2
A tough heat-resistant steel having the above high strength, normal temperature impact value of 3.5 kgf · m or more, transition temperature of 40 ° C. or less, and creep resistance at a high temperature of 400 ° C. or more can be obtained.

【0022】[0022]

【実施例】以下に本発明の実施例を示す。表1に本発明
例の鋼および比較例の鋼材の化学成分を示した。表2に
に示す熱処理条件で処理し、得られた結果(機械的試験
特性)を表3および表4にを示す。
Examples of the present invention will be described below. Table 1 shows the chemical components of the steel of the present invention and the steel of the comparative example. Tables 3 and 4 show the results (mechanical test characteristics) obtained by the treatment under the heat treatment conditions shown in Table 2.

【0023】[0023]

【表1】 [Table 1]

【0024】[0024]

【表2】 [Table 2]

【0025】[0025]

【表3】 [Table 3]

【0026】[0026]

【表4】 [Table 4]

【0027】これらによって本発明によるA〜Jの鋼は
適正な熱処理条件を選定することによりいずれも本発明
の目的とする常温靭性が高く、強度にも優れた耐熱鋼と
なっていることがわかる。特に、表3より負荷応力53
kgf/mm2 で482℃×100時間保定後の塑性歪み量が
0.15%以下の高温特性を有し、表4より550℃と
いう高温で優れた耐クリープ性を持つ強靭耐熱鋼が得ら
れることがわかる。
From these results, it can be understood that the steels A to J according to the present invention are all heat resistant steels having high room temperature toughness and excellent strength, which are the objects of the present invention, by selecting appropriate heat treatment conditions. . In particular, from Table 3, the load stress 53
kgf / mm plastic strain of 2 at 482 ° C. × 100 hours retention has high temperature characteristics of 0.15% or less, tough heat resisting steel is obtained having excellent creep resistance at a high temperature of Table 4 from 550 ° C. You can see that.

【0028】これに対し、K〜Oの鋼は化学成分および
熱処理条件が本発明の規定値を外れたもので、いずれも
強度、靭性のいずれかまたは両方が目標値を外れてしま
ったもので本発明の効果による差が顕著である。
On the other hand, the steels of K to O are those whose chemical composition and heat treatment conditions are outside the specified values of the present invention, and all of which have one or both of the strength and toughness outside the target values. The difference due to the effect of the present invention is remarkable.

【0029】[0029]

【発明の効果】以上の実施例からみても明らかな如く、
本発明によれば従来法により得られた鋼に比して同一強
度では靭性がはるかに優れており、目的とする強度・靭
性のバランスのとれた耐熱鋼を安価に製造することがで
きる。特に、ガス・タービンや蒸気タービン用のディス
ク或いはロータに好適であり、産業上に奏する効果は極
めて大きい。
As is clear from the above embodiments,
According to the present invention, the toughness is far superior at the same strength as compared with the steel obtained by the conventional method, and a heat-resistant steel having a desired balance between strength and toughness can be produced at low cost. In particular, it is suitable for disks or rotors for gas turbines and steam turbines, and has an extremely large industrial effect.

───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 FI F01D 5/28 F01D 5/28 ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 6 Identification code FI F01D 5/28 F01D 5/28

Claims (5)

【特許請求の範囲】[Claims] 【請求項1】 重量%で、 C :0.15〜0.25%、 Si≦0.2%、 Mn≦1.5%、 Ni≦1.5%、 Cr:2.8〜4.5%、 Mo:0.5〜2.0%、 V :0.10〜0.20%、 N :0.008〜0.025%、 Al≦0.03%、 O ≦0.0030% の成分からなり、残部がFeおよび不可避的不純物から
なることを特徴とする常温靭性が高く高温強度に優れた
耐熱鋼。
1. Weight%, C: 0.15 to 0.25%, Si ≦ 0.2%, Mn ≦ 1.5%, Ni ≦ 1.5%, Cr: 2.8 to 4.5 %, Mo: 0.5 to 2.0%, V: 0.10 to 0.20%, N: 0.008 to 0.025%, Al ≦ 0.03%, O ≦ 0.0030% A heat-resistant steel having high room-temperature toughness and excellent high-temperature strength, the balance being made of Fe and inevitable impurities.
【請求項2】 請求項1の成分にさらに重量%で、 Cu:0.5%以上1.5%以下、 Ca:0.001%以上0.007%以下 の一種または二種以上を含有させたことを特徴とする請
求項1記載の常温靭性が高く高温強度に優れた耐熱鋼。
2. The composition of claim 1, further comprising one or more of Cu: 0.5% or more and 1.5% or less, and Ca: 0.001% or more and 0.007% or less. 2. The heat-resistant steel according to claim 1, which has high room temperature toughness and excellent high-temperature strength.
【請求項3】 ガス・タービン用ディスクまたは蒸気タ
ービン用ディスクに用い、かつ常温での引張強度が10
0kgf/mm2 以上あることを特徴とする請求項1または2
に記載の常温靭性が高く高温強度に優れた耐熱鋼。
3. A disk for a gas turbine or a disk for a steam turbine and having a tensile strength of 10 at room temperature.
3. The method according to claim 1, wherein the weight is 0 kgf / mm 2 or more.
2. A heat-resistant steel having high normal-temperature toughness and excellent high-temperature strength as described in 1.
【請求項4】 ガス・タービンロータまたは蒸気タービ
ンロータに使用し、かつ常温での引張強度が85kgf/mm
2 以上あることを特徴とする請求項1または2に記載の
常温靭性が高く高温強度に優れた耐熱鋼。
4. A tensile strength at room temperature of 85 kgf / mm used for a gas turbine rotor or a steam turbine rotor.
3. The heat-resistant steel according to claim 1, wherein the heat-resistant steel has high room temperature toughness and excellent high-temperature strength.
【請求項5】 請求項1または2の鋼成分からなる鋼塊
または鋼片を1000℃以上の温度域に加熱し、ついで
熱間鍛造加工を行い、該加工を鋼片の中心温度が650
℃以上の温度範囲で終了し、冷却後、Ac3 変態点+5
0℃以上、1100℃以下の温度に1回以上再加熱して
から焼入れを行い、Ac1 以下の温度で1回以上焼戻す
ことを特徴とする常温靭性が高く高温強度に優れた耐熱
鋼の製造方法。
5. A steel ingot or a steel slab comprising the steel component according to claim 1 or 2 is heated to a temperature range of 1000 ° C. or higher, and then hot forging is performed.
Finished in a temperature range of ℃ or more, and cooled, then the Ac 3 transformation point +5
A heat-resistant steel with high room-temperature toughness and excellent high-temperature strength, characterized in that it is quenched after reheating to a temperature of 0 ° C or more and 1100 ° C or less once or more and tempered at a temperature of Ac 1 or less. Production method.
JP23960096A 1996-09-10 1996-09-10 High strength heat resistant steel and its production Pending JPH1088274A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP23960096A JPH1088274A (en) 1996-09-10 1996-09-10 High strength heat resistant steel and its production

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP23960096A JPH1088274A (en) 1996-09-10 1996-09-10 High strength heat resistant steel and its production

Publications (1)

Publication Number Publication Date
JPH1088274A true JPH1088274A (en) 1998-04-07

Family

ID=17047176

Family Applications (1)

Application Number Title Priority Date Filing Date
JP23960096A Pending JPH1088274A (en) 1996-09-10 1996-09-10 High strength heat resistant steel and its production

Country Status (1)

Country Link
JP (1) JPH1088274A (en)

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WO2009008281A1 (en) * 2007-07-10 2009-01-15 Usui Kokusai Sangyo Kaisha, Ltd. Steel tube for fuel injection tube and process for producing the same
JP2012225222A (en) * 2011-04-18 2012-11-15 Japan Steel Works Ltd:The Low alloy steel for geothermal power generation turbine rotor and low alloy material for geothermal power generation turbine rotor, and method for manufacturing the same
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1929054A1 (en) * 2005-09-29 2008-06-11 Hydril LLC Methods for heat treating thick-walled forgings
EP1929054A4 (en) * 2005-09-29 2010-03-31 Hydril Usa Mfg Llc Methods for heat treating thick-walled forgings
WO2009008281A1 (en) * 2007-07-10 2009-01-15 Usui Kokusai Sangyo Kaisha, Ltd. Steel tube for fuel injection tube and process for producing the same
JP2009019503A (en) * 2007-07-10 2009-01-29 Usui Kokusai Sangyo Kaisha Ltd Steel pipe for fuel injection pipe and its manufacturing method
US8795450B2 (en) 2007-07-10 2014-08-05 Usui Kokusai Sangyo Kaisha Manufacturing method for a steel pipe for fuel injection pipe
JP2012225222A (en) * 2011-04-18 2012-11-15 Japan Steel Works Ltd:The Low alloy steel for geothermal power generation turbine rotor and low alloy material for geothermal power generation turbine rotor, and method for manufacturing the same
US9034121B2 (en) 2011-04-18 2015-05-19 The Japan Steel Works,Ltd. Low alloy steel for geothermal power generation turbine rotor, and low alloy material for geothermal power generation turbine rotor and method for manufacturing the same
KR20190046729A (en) * 2011-04-18 2019-05-07 더 재팬 스틸 워크스 엘티디 Low alloy steel for geothermal power generation turbine rotor, and low alloy material for geothermal power generation turbine rotor and method for manufacturing the same
WO2015163226A1 (en) * 2014-04-23 2015-10-29 日本鋳鍛鋼株式会社 Turbine rotor material for geothermal power generation and method for manufacturing same
JP5869739B1 (en) * 2014-04-23 2016-02-24 日本鋳鍛鋼株式会社 Turbine rotor material for geothermal power generation and method for manufacturing the same

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