JP2004052060A - Steam turbine blade, steam turbine and high strength martensitic steel - Google Patents

Steam turbine blade, steam turbine and high strength martensitic steel Download PDF

Info

Publication number
JP2004052060A
JP2004052060A JP2002213247A JP2002213247A JP2004052060A JP 2004052060 A JP2004052060 A JP 2004052060A JP 2002213247 A JP2002213247 A JP 2002213247A JP 2002213247 A JP2002213247 A JP 2002213247A JP 2004052060 A JP2004052060 A JP 2004052060A
Authority
JP
Japan
Prior art keywords
less
steam turbine
total amount
blade
amount
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
JP2002213247A
Other languages
Japanese (ja)
Inventor
Masahiko Arai
新井 将彦
Hiroyuki Doi
土井 裕之
Kenichiro Nomura
野村 健一郎
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.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
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 Hitachi Ltd filed Critical Hitachi Ltd
Priority to JP2002213247A priority Critical patent/JP2004052060A/en
Publication of JP2004052060A publication Critical patent/JP2004052060A/en
Pending legal-status Critical Current

Links

Images

Landscapes

  • Turbine Rotor Nozzle Sealing (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blade material capable of making a moving blade in the final stage of a low pressure steam turbine long in length. <P>SOLUTION: The moving blade in the final stage is formed of martensitic steel comprising, by weight, 0.08 to 0.40% C, ≤0.50% Si, ≤1.50% Mn, 8.0 to 13.0% Cr, 2.0 to 3.5% Ni, 1.5 to 4.0% Mo, 0.05 to 0.35% V, one or two kinds of metals selected from Nb and Ta by >0.20 to 0.45% in total and 0.02 to 0.15% N, comprising one or two kinds of metals selected from Nb and Ta by >0.20 to 0.45% in total when the C content is ≤0.18%, and comprising one or two kinds of metals selected from Nb and Ta by >0.30 to 0.45% in total when the C content exceeds 0.18%, and the balance Fe with inevitable impurities, and having atotally tempered martensitic structure. The steel has high tensile strength, high toughness and high corrosion resistance, and thus can realize the lengthening of the blade. <P>COPYRIGHT: (C)2004,JPO

Description

【0001】
【発明の属する技術分野】
本発明は、蒸気タービン翼と蒸気タービン及びマルテンサイト鋼に関する。
【0002】
【従来の技術】
従来、蒸気タービンの動翼には12Cr−Mo−Ni−V−N鋼が使用されている。近年、省エネルギーの観点からタービンの熱効率の向上が要求され、省スペースの観点から機器のコンパクト化が要求されるようになった。
【0003】
熱効率を向上及び機器をコンパクト化するためには、低圧蒸気タービンの最終段動翼を長翼化するのが有効である。但し、長翼化を実現するには、高強度特に高引張強さを有する材料の開発が必要である。また低圧段で使用される材料は腐蝕環境下にあり、強度を高めるとともに耐食性、特に耐応力腐蝕割れ(SCC;Stress Corrosion Cracking)特性も高めなければならない。
【0004】
特開2000−161006号公報,特開2001−20704号公報及び特開2001−98349号公報には、低圧蒸気タービンの最終段動翼の長翼化をはかった発明、及び翼材料が記載されている。
【0005】
【発明が解決しようとする課題】
本発明は、翼部長さとして、3000rpmに対しては43インチ以上、3600rpmに対しては38インチ以上を実現することのできる高強度高耐食マルテンサイト鋼と、それを用いた蒸気タービン翼及び蒸気タービンを提供することにある。
【0006】
【課題を解決するための手段】
本発明は、蒸気タービン翼特に低圧蒸気タービンの最終段動翼を、重量で、C0.08〜0.40%,Si0.50%以下,Mn1.50% 以下,Cr8.0〜13.0%,Ni2.0〜3.5%,Mo1.5〜4.0% ,V0.05〜0.35%,Nb及びTaの1種又は2種の合計量が0.20を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18% 以下のときはNb及びTaの1種又は2種を合計量で0.20%を超え0.45% 以下含み、C量が0.18%を超えるときはNb及びTaの1種又は2種を合計量で0.30%を超え0.45%以下含み、残部がFe及び不可避不純物からなる鋼によって形成したことにある。
【0007】
前記鋼は、全焼戻しマルテンサイト組織を有するものであることが望ましい。また、室温の引張強さが120kgf/mm以上、特に128.5kgf/mm 以上であることが望ましい。C量は0.20〜0.35重量%の範囲が好ましい。
【0008】
本発明の蒸気タービン翼は、前記した化学成分を有する鋼を溶解,鍛造によって製造し、1000〜1100℃で0.5 〜3時間保持後室温まで急冷する焼入れ処理と、更に540〜620℃で1〜6時間保持後室温まで冷却する2回以上の焼戻し熱処理を施すことによって製造することが望ましい。特に、1000〜1100℃で0.5 〜3時間保持後室温まで急冷する処理を施した後、ドライアイスあるいは液体窒素温度まで冷却する深冷処理を施し、その後540〜620℃で1〜6時間保持後室温まで冷却する2回以上の焼戻し熱処理を施すことが望ましい。
【0009】
本発明は、前記化学成分を有する全焼戻しマルテンサイト組織のマルテンサイト鋼よりなり、室温の引張強さが128.5kgf/mm以上であり、翼長が965.2mm以上である低圧蒸気タービン最終段動翼を具備した3600rpm 蒸気タービンにある。また、前記化学成分を有する全焼戻しマルテンサイト組織のマルテンサイト鋼よりなり、室温の引張強さが128.5kgf/mm 以上であり、翼長が1092mm以上である低圧蒸気タービン最終段動翼を具備した3000rpm 蒸気タービンにある。これらの場合、マルテンサイト鋼の室温の引張強さは、特に130kgf/mm以上であることが望ましい。
【0010】
本発明はまた、重量で、C0.08〜0.40%,Si0.50%以下,Mn1.50%以下,Cr8.0〜13.0%,Ni2.0〜3.5%,Mo1.5〜4.0%,V0.05〜0.35%,Nb及びTaの1種又は2種の合計量が0.20 を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18%以下のときはNb及びTaの1種又は2種を合計量で0.20%を超え0.45%以下含み、C量が0.18% を超えるときはNb及びTaの1種又は2種を合計量で0.30%を超え0.45%以下含み、残部がFe及び不可避不純物からなることを特徴とする高強度マルテンサイト鋼にある。
【0011】
本発明に係るマルテンサイト鋼は、全焼戻しマルテンサイト組織を有することが望ましい。本発明のマルテンサイト鋼において、δフェライトが含まれると疲労強度が低下するので、δフェライトは全く含まないか、含んでも5%以下にすることが望ましい。δフェライト相を含まないようにするために、本発明では次式により計算されるCr当量が10以下になるように成分調整することが望ましい。
【0012】
Cr当量=Cr+6Si+4Mo+1.5W+11V+5Nb−40C−30N−30B−2Mn−4Ni−2Co+2.5Ta
本発明において、熱処理工程と熱処理時の加熱温度は、均質で高引張り強さの蒸気タービン長翼材を得るために重要である。溶解・鍛造後に調質処理として100℃〜1100℃で0.5 〜3時間加熱保持後、室温まで急冷する焼入れ処理を行うことが望ましい。急冷の方法としては、油焼入れが望ましい。加熱温度は1000℃〜1075℃が特に望ましい。残留オーステナイトを分解するために、更にドライアイス又は液体窒素温度まで冷却する深冷処理を施すことは望ましい。その後、540℃〜620℃で焼戻しを行う。焼戻し温度は、540℃〜590℃の範囲がより望ましい。焼戻し処理を2回行うことは更に望ましい。この場合、1回目は540℃〜570℃で行い、2回目は560℃〜590℃で行うのがよい。また、2回目の焼戻し温度は、1回目の焼戻し温度よりも高くするのがよい。焼戻し処理の加熱保持時間は、1回目及び2回目ともに1〜6時間が望ましい。1回目と2回目の焼戻し時間は,合計でも1〜6時間とすることが望ましい。
【0013】
Cは高い引張強さをえるために0.08% 以上とする。あまりCを多くすると、靭性を低下させるので0.40% 以下にする。特に、0.20〜0.35%が好ましく、より0.20〜0.30%が好ましい。
【0014】
Siは脱酸剤、Mnは脱硫剤・脱酸剤で鋼の溶解の際に添加するものであり、少量でも引張強さを損わず、低温靭性を高める効果がある。ただしSiはδフェライト生成元素であり、多量の添加は、疲労強度及び靭性を低下させる有害なδフェライト生成の原因になるので、0.50%以下が好ましい。特に、0.10%以下が好ましく、0.05% 以下がより好ましい。Si量の下限は0%であり、カーボン真空脱酸法或いはエレクトロスラグ再溶解法を採用することにより実現可能である。
【0015】
少量のMn添加は靭性を向上するが多量の添加は靭性を低下させるので、1.50% 以下が好ましい。特に、Mnは脱酸剤として有効なので、靭性向上の点から0.90%以下、特に0.40% 以下、より0.20% 以下が好ましい。
【0016】
Crは耐食性と引張強さを高めるが、13%以上添加するとδフェライト組織生成の原因になる。8%より少ないと耐食性と引張強さが不十分なので、Crは8〜13%が好ましい。特に強度の点から10.5〜12.5%が好ましく、より11〜12%が好ましい。
【0017】
Moは固溶強化及び炭化物・窒化物析出強化作用によって引張強さを高める効果がある。Mo1.5% 未満では引張強さ向上効果が不十分であり、4%以上になるとδフェライト生成原因になるので1.5〜4.0%が好ましい。特に、1.7〜3.5% 、より2.05〜3.0%が好ましい。なお、WおよびCoもMoと同じ様な効果があり、より高強度化のために上限で同等の含有量まで含有させることができる。
【0018】
Vは炭化物を析出し引張強さを高めると同時に靭性向上効果がある。
【0019】
V0.05% 以下ではその効果が不十分であり、δフェライト生成の抑制から0.35% 以下が望ましい。特に0.15〜0.30%が好ましく、0.20〜0.30%がより好ましい。
【0020】
Nbは、高引張強さで高靭性高耐食性とするために不可欠である。
【0021】
C量が0.18% 以下の場合はNb0.20%では不十分で、C量が0.18%を超えるときはNb0.30% では不十分である。δフェライト生成の抑制の点からNbの上限は0.45% が好ましい。Nbの代わりに或いはNbとともにTaを含有することができる。NbとTaの合計量は0.2〜0.45重量%とする。
【0022】
Niは低温靭性を高めると共に、δフェライト生成の防止効果がある。この効果は、Ni2%未満では不十分で、3.5% を超える添加で効果が飽和する。特に、2.6〜3.2%が好ましい。
【0023】
Nは引張強さの向上及びδフェライトの生成防止に効果があるが0.02% 未満ではその効果が十分でなく、0.15% を超えると靭性を低下させる。特に、0.06〜0.10%の範囲で優れた特性が得られる。
【0024】
P及びSの低減は、引張強さを損なわず、低温靭性を高める効果があり、極力低減することが望ましい。低温靭性向上の点からP0.015%以下,S0.015%以下が好ましい。特に、P0.010%以下,S0.010%以下が望ましい。Sb,Sn及びAsの低減も、低温靭性を高める効果があるので極力低減することが望ましい。現状製鋼技術レベルの点から、Sb0.0015%以下,Sn0.01%以下、及びAs0.02% 以下にすべきである。できればSb0.001%以下,Sn0.005%及びAs0.01%以下が望ましい。
【0025】
さらに、本発明においては、Mn/Ni比を0.11以下にすること、又Ti,Zr,Hf等のMC炭化物形成元素を1種又は2種,3種の各々の組み合わせで合計で0.5%以下含むものが好ましい。
【0026】
本発明材の熱処理は、まず完全なオーステナイトに変態するに十分な温度である最低1000℃,最高1100℃に均一加熱し、急冷し(好ましくは油冷)、次いで540〜570℃の温度に加熱保持・冷却し(第1次焼戻し)、次いで560〜620℃の温度に加熱保持・冷却(第2次焼戻し)を行い、全焼戻しマルテンサイト組織とすることが好ましい。
【0027】
【発明の実施の形態】
〔実施例1〕
表1は蒸気タービン長翼材に係る12%Cr鋼の化学組成(重量%)を示し、残部はFeである。各試料はそれぞれ150kg真空アーク溶解し、1150℃に加熱して鍛造して実験素材とした。試料No.1は、1000℃で1時間加熱後油焼入れにより室温まで冷却し、次いで、570℃に加熱し2時間保持後室温まで空冷した。No.2は、1050℃で1時間加熱後油焼入れにより室温まで冷却し、次いで、570℃に2時間保持後室温まで空冷した。試料No.3〜6は、1050℃で1時間加熱後油焼き入れ、No.7,8は1075℃で1時間加熱後油焼き入れにより室温まで冷却し、次いで560℃(低温戻し)に加熱し2時間保持後室温まで空冷し(一次焼戻し)、更に580℃(高温戻し)に加熱し2時間保持後室温まで空冷した(二次焼戻し)。試料No.9,10は1075℃で1時間加熱後油焼入れにより室温まで冷却し、次いで液体窒素温度までの深冷処理を行い、更に570℃に加熱し2時間保持後室温まで空冷した。いずれの試料も全焼戻しマルテンサイト組織を有していた。表1において、No.4〜10は本発明に係る材料、およびNo.1〜3は、比較材である。
【0028】
表2はこれら試料の室温(20℃)の機械的性質を示す。比較材(No.1〜3)と本発明に係る材料(No.4〜10)は翼部長さ43インチ以上の3000rpm 蒸気タービン用材料として要求される引張強さ128.5kgf/mm を満足する。しかし、Nb濃度の高いNo.2は衝撃値が低く、3.8kgf−m/cm の要求値を満足できない。
【0029】
【表1】

Figure 2004052060
【0030】
【表2】
Figure 2004052060
【0031】
図1は、耐食性評価に用いた低歪み速度試験(SSRT試験)結果を示す。破断応力比は(腐食環境下の破断応力)/(N ガス雰囲気下の破断応力)で定義され、数値の高いものほど耐食性に優れる。比較材No.1,3は破断応力比が低く、耐食性が悪い。比較材No.2は強度,耐食性に優れるが、衝撃値が低い。開発材は強度,衝撃値,耐食性のいずれも優れた結果を示した。
【0032】
〔実施例2〕
図2は実施例1のNo.4〜8に記載の鋼を用いた3000rpm 用の翼部長さ1168mm(46″)長翼の外観図である。1は高速蒸気が突き当たる翼プロファイル部を、2はロータシャフトへの翼植込部を、3は翼の遠心力を支えるためのピンを挿入する穴を、4は蒸気中の水滴によるエロージョンを防止するためのエロージョンシールド(ステライト板を溶接)、5はタイボス、6はコンティニュアスカバーである。
【0033】
図2に示す46″長翼はエレクトロスラグ再溶解法により溶製し、鍛造・熱処理を行った。鍛造は850〜1150℃の温度範囲内で、熱処理は実施例1に示した条件で行った。この長翼の金属組織は全焼戻しマルテンサイト組織であった。翼プロファイル部1は植え込み部の厚さが最も大きく、先端部になるに従って徐々に薄肉となっている。
【0034】
図3は、本発明の46″長翼を使用した蒸気タービンの一実施例を示す。
【0035】
【発明の効果】
本発明によれば、蒸気タービンの長翼に要求される引張強さ及び靭性が満足される物が得られ、この長翼を使用した蒸気タービンは極めて高い熱効率とコンパクト化が達成される顕著な効果が発揮される。
【図面の簡単な説明】
【図1】本発明材と比較材の特性を示す図。
【図2】本発明に係る蒸気タービン動翼の正面図。
【図3】本発明に係る蒸気タービンの断面図。
【符号の説明】
1…翼プロファイル部、2…翼植込部、3…ピン穴、4…エロージョンシールド、5…タイボス、6…コンティニュアスカバー。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a steam turbine blade, a steam turbine, and martensite steel.
[0002]
[Prior art]
Conventionally, 12Cr-Mo-Ni-VN steel has been used for the moving blade of a steam turbine. In recent years, improvement in thermal efficiency of turbines has been demanded from the viewpoint of energy saving, and downsizing of equipment has been demanded from the viewpoint of space saving.
[0003]
In order to improve the thermal efficiency and make the equipment compact, it is effective to make the last-stage moving blade of the low-pressure steam turbine longer. However, in order to realize a longer blade, it is necessary to develop a material having high strength, particularly high tensile strength. Further, the material used in the low pressure stage is in a corrosive environment, and it is necessary to increase strength and corrosion resistance, in particular, stress corrosion cracking (SCC).
[0004]
JP-A-2000-161006, JP-A-2001-20704, and JP-A-2001-98349 describe an invention in which the last-stage moving blade of a low-pressure steam turbine is made longer, and a blade material. I have.
[0005]
[Problems to be solved by the invention]
The present invention relates to a high-strength and high-corrosion-resistant martensitic steel capable of realizing a blade length of 43 inches or more for 3000 rpm and 38 inches or more for 3600 rpm, and a steam turbine blade and steam using the same. It is to provide a turbine.
[0006]
[Means for Solving the Problems]
The present invention provides a steam turbine blade, particularly a final stage rotor blade of a low-pressure steam turbine, in which, by weight, C 0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, and Cr 8.0 to 13.0%. , Ni 2.0-3.5%, Mo 1.5-4.0%, V 0.05-0.35%, the total amount of one or two of Nb and Ta exceeds 0.20 and 0.45% When N content is 0.02 to 0.15% and C content is 0.18% or less, the total amount of one or two of Nb and Ta exceeds 0.20% and 0.45% or less. When the C content exceeds 0.18%, one or two of Nb and Ta are contained in a total amount of more than 0.30% to 0.45% or less, and the balance is formed of steel composed of Fe and unavoidable impurities. I did it.
[0007]
The steel desirably has a fully tempered martensite structure. Further, it is desirable that the tensile strength at room temperature is 120 kgf / mm 2 or more, particularly 128.5 kgf / mm 2 or more. The C content is preferably in the range of 0.20 to 0.35% by weight.
[0008]
The steam turbine blade of the present invention is manufactured by melting and forging a steel having the above-mentioned chemical composition, holding at 1000 to 1100 ° C. for 0.5 to 3 hours, then quenching to room temperature, and further performing quenching at 540 to 620 ° C. It is desirable to perform the production by performing two or more tempering heat treatments of cooling to room temperature after holding for 1 to 6 hours. In particular, after holding at 1000 to 1100 ° C. for 0.5 to 3 hours, performing a process of rapidly cooling to room temperature, then performing a deep cooling process of cooling to dry ice or liquid nitrogen temperature, and then performing at 540 to 620 ° C. for 1 to 6 hours. It is desirable to perform two or more tempering heat treatments of cooling to room temperature after holding.
[0009]
The present invention relates to a low-pressure steam turbine comprising a fully tempered martensitic steel having the above chemical composition, having a tensile strength at room temperature of 128.5 kgf / mm 2 or more and a blade length of 965.2 mm or more. In a 3600 rpm steam turbine with staged buckets. Further, a final stage rotor blade of a low-pressure steam turbine having a tempered martensite steel having the above-mentioned chemical components, a tensile strength at room temperature of 128.5 kgf / mm 2 or more, and a blade length of 1092 mm or more. Equipped with 3000rpm steam turbine. In these cases, the tensile strength at room temperature of the martensitic steel is desirably 130 kgf / mm 2 or more.
[0010]
The present invention also provides, by weight, C 0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, Cr 8.0 to 13.0%, Ni 2.0 to 3.5%, Mo 1.5. -4.0%, V0.05-0.35%, total amount of one or two of Nb and Ta is more than 0.20 and 0.45% or less, and N0.02-0.15% When the C amount is 0.18% or less, the total amount of one or two of Nb and Ta is more than 0.20% and 0.45% or less, and when the C amount is more than 0.18%, A high-strength martensitic steel containing one or two of Nb and Ta in a total amount of more than 0.30% and 0.45% or less, with the balance being Fe and unavoidable impurities.
[0011]
The martensitic steel according to the present invention preferably has a fully tempered martensite structure. In the martensitic steel of the present invention, when δ ferrite is contained, the fatigue strength is reduced. Therefore, it is desirable that δ ferrite is not contained at all, or even if it is contained, it is 5% or less. In order to exclude the δ ferrite phase, in the present invention, it is desirable to adjust the components so that the Cr equivalent calculated by the following equation becomes 10 or less.
[0012]
Cr equivalent = Cr + 6Si + 4Mo + 1.5W + 11V + 5Nb-40C-30N-30B-2Mn-4Ni-2Co + 2.5Ta
In the present invention, the heat treatment step and the heating temperature during the heat treatment are important for obtaining a steam turbine long blade material having a uniform and high tensile strength. After the melting and forging, it is preferable to perform a quenching treatment of heating and holding at 100 ° C. to 1100 ° C. for 0.5 to 3 hours, followed by rapid cooling to room temperature. As a quenching method, oil quenching is desirable. The heating temperature is particularly preferably from 1000C to 1075C. In order to decompose the retained austenite, it is preferable to further perform a deep cooling treatment to cool to a temperature of dry ice or liquid nitrogen. Thereafter, tempering is performed at 540 ° C to 620 ° C. The tempering temperature is more preferably in the range of 540 ° C to 590 ° C. It is more desirable to perform the tempering twice. In this case, the first time is preferably performed at 540 ° C. to 570 ° C., and the second time is preferably performed at 560 ° C. to 590 ° C. The second tempering temperature is preferably higher than the first tempering temperature. The heating and holding time of the tempering treatment is desirably 1 to 6 hours in each of the first and second times. The first and second tempering times are desirably 1 to 6 hours in total.
[0013]
C is set to 0.08% or more to obtain a high tensile strength. If C is excessively increased, the toughness is reduced. In particular, 0.20 to 0.35% is preferable, and 0.20 to 0.30% is more preferable.
[0014]
Si is a deoxidizing agent, and Mn is a desulfurizing agent and a deoxidizing agent, which are added at the time of melting of steel. Even if it is a small amount, it has the effect of increasing the low-temperature toughness without impairing the tensile strength. However, Si is a δ ferrite-forming element, and if added in a large amount, causes harmful δ-ferrite formation which lowers fatigue strength and toughness, so 0.50% or less is preferable. In particular, 0.10% or less is preferable, and 0.05% or less is more preferable. The lower limit of the amount of Si is 0%, which can be realized by employing a carbon vacuum deoxidation method or an electroslag remelting method.
[0015]
The addition of a small amount of Mn improves the toughness, but the addition of a large amount lowers the toughness. In particular, since Mn is effective as a deoxidizing agent, the content is preferably 0.90% or less, particularly 0.40% or less, more preferably 0.20% or less from the viewpoint of improving toughness.
[0016]
Cr enhances corrosion resistance and tensile strength, but when added in an amount of 13% or more, it causes the formation of a δ ferrite structure. If it is less than 8%, the corrosion resistance and tensile strength are insufficient, so that the Cr content is preferably 8 to 13%. Particularly, from the viewpoint of strength, it is preferably 10.5 to 12.5%, more preferably 11 to 12%.
[0017]
Mo has the effect of increasing the tensile strength by the action of solid solution strengthening and carbide / nitride precipitation strengthening. If the Mo content is less than 1.5%, the effect of improving the tensile strength is insufficient, and if the Mo content is 4% or more, δ ferrite may be formed, so the content is preferably 1.5 to 4.0%. In particular, it is preferably 1.7 to 3.5%, more preferably 2.05 to 3.0%. Note that W and Co have the same effect as Mo, and can be contained up to the same content at the upper limit for higher strength.
[0018]
V has the effect of increasing the tensile strength by precipitating carbides and improving the toughness.
[0019]
If the V value is less than 0.05%, the effect is insufficient, and from the viewpoint of suppressing the formation of δ ferrite, the content is desirably 0.35% or less. In particular, 0.15 to 0.30% is preferable, and 0.20 to 0.30% is more preferable.
[0020]
Nb is indispensable for high tensile strength, high toughness and high corrosion resistance.
[0021]
When the amount of C is 0.18% or less, Nb 0.20% is insufficient, and when the amount of C exceeds 0.18%, Nb 0.30% is insufficient. From the viewpoint of suppressing the formation of δ ferrite, the upper limit of Nb is preferably 0.45%. Ta can be contained instead of or together with Nb. The total amount of Nb and Ta is 0.2 to 0.45% by weight.
[0022]
Ni enhances low-temperature toughness and has an effect of preventing the formation of δ ferrite. This effect is insufficient when the content of Ni is less than 2%, and the effect is saturated when the content is more than 3.5%. In particular, 2.6 to 3.2% is preferable.
[0023]
N is effective in improving tensile strength and preventing the formation of δ ferrite, but if it is less than 0.02%, its effect is not sufficient, and if it exceeds 0.15%, toughness is reduced. In particular, excellent characteristics are obtained in the range of 0.06 to 0.10%.
[0024]
The reduction of P and S has the effect of increasing the low-temperature toughness without impairing the tensile strength, and it is desirable to reduce as much as possible. From the viewpoint of improving low-temperature toughness, P is preferably 0.015% or less and S is 0.015% or less. In particular, P is preferably 0.010% or less and S 0.010% or less. Since reduction of Sb, Sn and As also has the effect of increasing low-temperature toughness, it is desirable to reduce as much as possible. From the point of the current steelmaking technology level, Sb should be 0.0015% or less, Sn 0.01% or less, and As0.02% or less. If possible, Sb 0.001% or less, Sn 0.005% and As 0.01% or less are desirable.
[0025]
Furthermore, in the present invention, the Mn / Ni ratio is set to 0.11 or less, and a total of 0.1, 2, or 3 types of MC carbide forming elements such as Ti, Zr, and Hf are combined. Those containing 5% or less are preferred.
[0026]
In the heat treatment of the material of the present invention, the material is first uniformly heated to a minimum temperature of 1000 ° C. and a maximum temperature of 1100 ° C., which is sufficient to transform into austenite, rapidly cooled (preferably oil cooled), and then heated to a temperature of 540 to 570 ° C. It is preferable to perform holding and cooling (primary tempering), and then heat and hold and cool (secondary tempering) to a temperature of 560 to 620 ° C. to obtain a fully tempered martensitic structure.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
[Example 1]
Table 1 shows the chemical composition (% by weight) of 12% Cr steel related to the steam turbine long blade material, and the balance is Fe. Each sample was melted in a vacuum arc of 150 kg, heated to 1150 ° C., and forged to obtain an experimental material. Sample No. 1 was heated at 1000 ° C. for 1 hour, cooled to room temperature by oil quenching, then heated to 570 ° C., held for 2 hours, and air-cooled to room temperature. No. 2 was heated at 1050 ° C. for 1 hour, cooled to room temperature by oil quenching, then kept at 570 ° C. for 2 hours and air-cooled to room temperature. Sample No. Nos. 3 to 6 were heated at 1050 ° C. for 1 hour and then oil-hardened. 7 and 8 were heated at 1075 ° C. for 1 hour, cooled to room temperature by oil quenching, then heated to 560 ° C. (low temperature return), held for 2 hours, air-cooled to room temperature (primary temper), and further at 580 ° C. (high temperature return). After heating for 2 hours, the mixture was air-cooled to room temperature (secondary tempering). Sample No. Samples 9 and 10 were heated at 1075 ° C. for 1 hour, cooled to room temperature by oil quenching, deep-cooled to liquid nitrogen temperature, further heated to 570 ° C., held for 2 hours, and air-cooled to room temperature. All samples had a fully tempered martensite structure. In Table 1, No. Nos. 4 to 10 are the materials according to the present invention, and Nos. 4 to 10. 1 to 3 are comparative materials.
[0028]
Table 2 shows the mechanical properties of these samples at room temperature (20 ° C.). The comparative material (Nos. 1 to 3) and the material according to the present invention (Nos. 4 to 10) satisfy the tensile strength of 128.5 kgf / mm 2 required as a material for a steam turbine having a blade length of 43 inches or more and 3000 rpm. I do. However, when the Nb concentration is high, No. 2 has a low impact value and cannot satisfy the required value of 3.8 kgfm-cm / cm 2 .
[0029]
[Table 1]
Figure 2004052060
[0030]
[Table 2]
Figure 2004052060
[0031]
FIG. 1 shows the results of a low strain rate test (SSRT test) used for corrosion resistance evaluation. The rupture stress ratio is defined as (rupture stress in a corrosive environment) / (rupture stress in an N 2 gas atmosphere), and the higher the numerical value, the better the corrosion resistance. Comparative material No. Nos. 1 and 3 have a low breaking stress ratio and poor corrosion resistance. Comparative material No. No. 2 is excellent in strength and corrosion resistance, but has a low impact value. The developed material showed excellent results in all of strength, impact value and corrosion resistance.
[0032]
[Example 2]
FIG. 4 is an external view of a blade having a blade length of 1168 mm (46 ″) for steel at 3000 rpm for use with steel described in Nos. 4 to 8. 1 is a blade profile portion against which high-speed steam strikes, 2 is a blade implant portion on a rotor shaft. 3 is a hole for inserting a pin to support the centrifugal force of the wing, 4 is an erosion shield (welding a stellite plate) to prevent erosion due to water droplets in steam, 5 is a tie boss, and 6 is a continuous skater. It is a bar.
[0033]
The 46 ″ long blade shown in FIG. 2 was melted by the electroslag remelting method and forged and heat-treated. The forging was performed within a temperature range of 850 to 1150 ° C., and the heat treatment was performed under the conditions shown in Example 1. The metal structure of this long blade was a fully tempered martensite structure, and the blade profile portion 1 had the largest thickness at the implanted portion, and gradually became thinner toward the tip.
[0034]
FIG. 3 shows an embodiment of a steam turbine using 46 "long blades of the present invention.
[0035]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the thing which satisfies the tensile strength and toughness required for the long blade of a steam turbine is obtained, and the steam turbine using this long blade achieves extremely high thermal efficiency and compactness. The effect is exhibited.
[Brief description of the drawings]
FIG. 1 is a graph showing characteristics of a material of the present invention and a comparative material.
FIG. 2 is a front view of a steam turbine blade according to the present invention.
FIG. 3 is a sectional view of a steam turbine according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... wing profile part, 2 ... wing implantation part, 3 ... pin hole, 4 ... erosion shield, 5 ... tie boss, 6 ... continuous cover.

Claims (12)

重量で、C0.08〜0.40%,Si0.50%以下,Mn1.50%以下,Cr8.0〜13.0%,Ni2.0〜3.5% ,Mo1.5〜4.0%,V0.05〜0.35%,Nb及びTaの1種又は2種の合計量が0.20% を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18% 以下のときはNb及びTaの1種又は2種を合計量で0.20%を超え0.45%以下含み、C量が0.18%を超えるときはNb及びTaの1種又は2種を合計量で0.30%を超え0.45% 以下含み、残部がFe及び不可避不純物からなる鋼により形成されたことを特徴とする蒸気タービン翼。By weight, C 0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, Cr 8.0 to 13.0%, Ni 2.0 to 3.5% 〜, Mo 1.5 to 4.0%. , V 0.05 to 0.35%, the total amount of one or two of Nb and Ta is more than 0.20% and not more than 0.45%, and N is 0.02 to 0.15%. Is 0.18% or less, the total content of one or two of Nb and Ta is more than 0.20% and 0.45% or less, and when the C content is more than 0.18%, the content of Nb and Ta is A steam turbine blade comprising one or two kinds in a total amount of more than 0.30% to 0.45% or less and a balance of steel made of Fe and unavoidable impurities. 請求項1において、前記鋼が全焼戻しマルテンサイト組織を有することを特徴とする蒸気タービン翼。The steam turbine blade according to claim 1, wherein the steel has a fully tempered martensite structure. 請求項1または2において、前記鋼の室温の引張強さが120kgf/mm以上であることを特徴とする蒸気タービン翼。According to claim 1 or 2, a steam turbine blade tensile strength at room temperature of the steel is equal to or is 120 kgf / mm 2 or more. 請求項1ないし3のいずれか1つに記載の鋼により形成された低圧蒸気タービン最終段翼。A low-pressure steam turbine last stage blade formed of the steel according to any one of claims 1 to 3. 重量で、C0.08〜0.40%,Si0.50%以下,Mn1.50%以下,Cr8.0〜13.0%,Ni2.0〜3.5%,Mo1.5〜4.0% ,V0.05〜0.35%,Nb及びTaの1種又は2種の合計量が0.20% を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18% 以下のときはNb及びTaの1種又は2種の合計量が0.20%を超え0.45%以下であり、C量が0.18%を超えるときはNb及びTaの1種又は2種の合計量が0.30%を超え0.45% 以下であり、残部がFe及び不可避不純物からなり、溶解及び鍛造された鋼に、1000〜1100℃で0.5 〜3時間保持後室温まで急冷する焼入れ処理と、更に540〜620℃で1〜6時間保持後室温まで冷却する2回以上の焼戻し熱処理を施して蒸気タービン翼とすることを特徴とする蒸気タービン翼の製造方法。By weight, C 0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, Cr 8.0 to 13.0%, Ni 2.0 to 3.5%, Mo 1.5 to 4.0% , V 0.05 to 0.35%, the total amount of one or two of Nb and Ta is more than 0.20% and not more than 0.45%, and N is 0.02 to 0.15%. Is 0.18% or less, the total amount of one or two of Nb and Ta is more than 0.20% and 0.45% or less, and when the C amount is more than 0.18%, Nb and Ta are The total amount of one or two of the above is more than 0.30% and 0.45% or less, and the balance is composed of Fe and inevitable impurities. A quenching treatment of rapidly cooling to room temperature after holding for 3 hours, and further cooling to room temperature after holding for 1 to 6 hours at 540 to 620 ° C Method for producing a steam turbine blade, characterized in that twice subjected to more tempering heat treatment and steam turbine blades that. 請求項5において、前記溶解及び鍛造された鋼に1000〜1100℃で0.5〜3時間保持後室温まで急冷する焼入れ処理を施した後、ドライアイスあるいは液体窒素温度まで深冷処理する熱処理を施し、その後540〜620℃で1〜6時間保持後室温まで冷却する2回以上の焼戻し熱処理を施すことを特徴とする蒸気タービン翼の製造方法。6. The heat treatment according to claim 5, wherein the melted and forged steel is subjected to a quenching treatment of rapidly cooling to room temperature after holding at 1000 to 1100 ° C. for 0.5 to 3 hours and then a deep cooling treatment to a temperature of dry ice or liquid nitrogen. A tempering heat treatment of holding at 540 to 620 ° C. for 1 to 6 hours and then cooling to room temperature. 請求項5または6において、前記焼戻し処理を第1回目は540〜570℃の温度まで加熱して行い、第2回目は560〜620℃の温度で行い、第1回目よりも第2回目の温度を高くすることを特徴とする蒸気タービン翼の製造方法。7. The tempering process according to claim 5, wherein the first time is performed by heating to a temperature of 540 to 570 ° C., the second time is performed at a temperature of 560 to 620 ° C., and the second time is performed more than the first time. A method for manufacturing a steam turbine blade, characterized in that: 低圧蒸気タービン最終段翼が重量で、C0.08〜0.40% ,Si0.50%以下,Mn1.50%以下,Cr8.0〜13.0%,Ni2.0〜3.5% ,Mo1.5〜4.0%,V0.05〜0.35%,Nb及びTaの1種又は2種の合計量が0.20を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18%以下のときはNb及びTaの1種又は2種を合計量で0.20%を超え0.45%以下含み、C量が0.18%を超えるときはNb及びTaの1種又は2種を合計量で0.30%を超え0.45%以下含み、残部がFe及び不可避不純物からなり、全焼戻しマルテンサイト組織を有するマルテンサイト鋼からなり、室温の引張強さが128.5kgf/mm以上であり、翼長が965.2mm以上であることを特徴とする3600rpm 蒸気タービン。The final stage blade of the low-pressure steam turbine is C0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, Cr 8.0 to 13.0%, Ni 2.0 to 3.5%, Mo1. 0.5 to 4.0%, V 0.05 to 0.35%, the total amount of one or two of Nb and Ta exceeds 0.20 and 0.45% or less, and N 0.02 to 0.15% And when the C amount is 0.18% or less, the total amount of one or two of Nb and Ta exceeds 0.20% and 0.45% or less, and the C amount exceeds 0.18%. Sometimes, one or two of Nb and Ta are contained in a total amount of more than 0.30% and 0.45% or less, the balance being Fe and unavoidable impurities, and a martensitic steel having a fully tempered martensitic structure, and a tensile strength at room temperature is 128.5kgf / mm 2 or more, the blade length is 965.2mm than 3600rpm steam turbine, characterized in that it. 低圧蒸気タービン最終段翼が重量で、C0.08〜0.40% ,Si0.50%以下,Mn1.50%以下,Cr8.0〜13.0%,Ni2.0〜3.5% ,Mo1.5〜4.0%,V0.05〜0.35%,Nb及びTaの1種又は2種の合計量が0.20を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18%以下のときはNb及びTaの1種又は2種を合計量で0.20%を超え0.45%以下含み、C量が0.18%を超えるときはNb及びTaの1種又は2種を合計量で0.30%を超え0.45%以下含み、残部がFe及び不可避不純物からなり、全焼戻しマルテンサイト組織を有し、室温の引張強さが128.5kgf/mm 以上であるマルテンサイト鋼によって形成され、翼長が1092mm以上であることを特徴とする3000rpm 蒸気タービン。The final stage blade of the low-pressure steam turbine is C0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, Cr 8.0 to 13.0%, Ni 2.0 to 3.5%, Mo1. 0.5 to 4.0%, V 0.05 to 0.35%, the total amount of one or two of Nb and Ta exceeds 0.20 and 0.45% or less, and N 0.02 to 0.15% And when the C amount is 0.18% or less, the total amount of one or two of Nb and Ta exceeds 0.20% and 0.45% or less, and the C amount exceeds 0.18%. Sometimes, one or two of Nb and Ta are contained in a total amount of more than 0.30% to 0.45% or less, the balance being Fe and unavoidable impurities, having a fully tempered martensite structure, and a tensile strength at room temperature. formed by martensitic steel is Saga 128.5kgf / mm 2 or more, the blade length is 1092m 3000rpm steam turbine, characterized in that at least. 重量で、C0.08〜0.40%,Si0.50%以下,Mn1.50%以下,Cr8.0〜13.0%,Ni2.0〜3.5%,Mo1.5〜4.0% ,V0.05〜0.35% ,Nb及びTaの1種又は2種の合計量が0.20を超え0.45%以下、及びN0.02〜0.15%を含有し、C量が0.18% 以下のときはNb及びTaの1種又は2種の合計量が0.20%を超え0.45%以下であり、C量が0.18%を超えるときはNb及びTaの1種又は2種の合計量が0.30%を超え0.45% 以下であり、残部がFe及び不可避不純物からなることを特徴とする高強度マルテンサイト鋼。By weight, C 0.08 to 0.40%, Si 0.50% or less, Mn 1.50% or less, Cr 8.0 to 13.0%, Ni 2.0 to 3.5%, Mo 1.5 to 4.0% , V 0.05 to 0.35%}, the total amount of one or two of Nb and Ta is more than 0.20 and 0.45% or less, and N is 0.02 to 0.15%, and the C content is When the amount of Nb and Ta is 0.18% or less, the total amount of one or two of Nb and Ta is more than 0.20% and 0.45% or less, and when the amount of C exceeds 0.18%, the content of Nb and Ta is A high-strength martensitic steel, wherein the total amount of one or two kinds is more than 0.30% and not more than 0.45%, with the balance being Fe and unavoidable impurities. 請求項1において、前記C量が0.20〜0.35%よりなることを特徴とする蒸気タービン翼。The steam turbine blade according to claim 1, wherein the C amount is 0.20 to 0.35%. 請求項8又は9において、前記マルテンサイト鋼の室温の引張強さが140kgf/mm以上よりなることを特徴とする蒸気タービン。According to claim 8 or 9, a steam turbine tensile strength at room temperature of the martensitic steel is characterized by consisting of 140 kgf / mm 2 or more.
JP2002213247A 2002-07-23 2002-07-23 Steam turbine blade, steam turbine and high strength martensitic steel Pending JP2004052060A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2002213247A JP2004052060A (en) 2002-07-23 2002-07-23 Steam turbine blade, steam turbine and high strength martensitic steel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2002213247A JP2004052060A (en) 2002-07-23 2002-07-23 Steam turbine blade, steam turbine and high strength martensitic steel

Publications (1)

Publication Number Publication Date
JP2004052060A true JP2004052060A (en) 2004-02-19

Family

ID=31935889

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2002213247A Pending JP2004052060A (en) 2002-07-23 2002-07-23 Steam turbine blade, steam turbine and high strength martensitic steel

Country Status (1)

Country Link
JP (1) JP2004052060A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102191439A (en) * 2011-04-27 2011-09-21 四川六合锻造股份有限公司 Stainless steel material used for blades and bolts of nuclear power steam turbine and preparation method thereof
WO2019086934A1 (en) * 2017-11-03 2019-05-09 Aperam Martensitic stainless steel and method for producing same
CN115029524A (en) * 2022-04-29 2022-09-09 沈阳鼓风机集团往复机有限公司 Cryogenic treatment process for S51740 material

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102191439A (en) * 2011-04-27 2011-09-21 四川六合锻造股份有限公司 Stainless steel material used for blades and bolts of nuclear power steam turbine and preparation method thereof
WO2019086934A1 (en) * 2017-11-03 2019-05-09 Aperam Martensitic stainless steel and method for producing same
CN111902551A (en) * 2017-11-03 2020-11-06 艾普伦 Martensitic stainless steel and method for producing same
US11702717B2 (en) 2017-11-03 2023-07-18 Aperam Martensitic stainless steel and method for producing the same
CN115029524A (en) * 2022-04-29 2022-09-09 沈阳鼓风机集团往复机有限公司 Cryogenic treatment process for S51740 material
CN115029524B (en) * 2022-04-29 2024-01-19 沈阳鼓风机集团往复机有限公司 Cryogenic treatment process for S51740 material

Similar Documents

Publication Publication Date Title
JPH0563544B2 (en)
CN102517517B (en) Refractory steel for vane of steam turbine of ultra supercritical fossil power plant and manufacturing method
JP6317542B2 (en) Steam turbine rotor
JP2005171339A (en) High strength high toughness high corrosion resistance martensite steel, steam turbine blade, and steam turbine power plant
JP3962743B2 (en) Precipitation hardening type martensitic steel, method for producing the same, turbine rotor blade and steam turbine using the same
JPH09296258A (en) Heat resistant steel and rotor shaft for steam turbine
CN102517507B (en) Steel for blades of turbine of ultra-supercritical fossil power plants and manufacturing method
JPH10251809A (en) High toughness ferritic heat resistant steel
JP3921574B2 (en) Heat-resistant steel, gas turbine using the same, and various components
JPS6054385B2 (en) heat resistant steel
JP2006022343A (en) Heat resistant steel, rotor shaft for steam turbine using it, steam turbine, and power plant with the use of steam turbine
JP5265325B2 (en) Heat resistant steel with excellent creep strength and method for producing the same
JP4702267B2 (en) Precipitation hardening type martensitic stainless steel
JP2004052060A (en) Steam turbine blade, steam turbine and high strength martensitic steel
JP2002047530A (en) Heat resistant steel, method for heat treating heat resistant steel and heat resistant steel parts
JPH11209851A (en) Gas turbine disk material
JP5981357B2 (en) Heat resistant steel and steam turbine components
JP3345988B2 (en) Steam turbine rotor
JPH1036944A (en) Martensitic heat resistant steel
JP4519722B2 (en) High and low pressure integrated steam turbine rotor and its manufacturing method, and high and low pressure integrated steam turbine and its manufacturing method
US11788177B2 (en) Precipitation-hardened stainless steel alloys
JP2004018897A (en) High-chromium alloy steel and turbine rotor using this
US20170356070A1 (en) Maraging steel
JPH1018003A (en) Gas turbine, gas turbine disk, and their production
JPH05263657A (en) High efficiency gas turbine and disc used in it