JPH108217A - Stainless steel for steam turbine blade, excellent in pitting corrosion resistance - Google Patents
Stainless steel for steam turbine blade, excellent in pitting corrosion resistanceInfo
- Publication number
- JPH108217A JPH108217A JP17437896A JP17437896A JPH108217A JP H108217 A JPH108217 A JP H108217A JP 17437896 A JP17437896 A JP 17437896A JP 17437896 A JP17437896 A JP 17437896A JP H108217 A JPH108217 A JP H108217A
- Authority
- JP
- Japan
- Prior art keywords
- corrosion resistance
- pitting corrosion
- steel
- stainless steel
- steam turbine
- 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
Links
Landscapes
- Turbine Rotor Nozzle Sealing (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、原子力用給水ポン
プの駆動用蒸気タービン用動翼材に関するもので、動翼
材としての基本強度を有し、かつ室温から２００℃まで
の温度域の湿り蒸気中で、優れた耐孔食性を有するステ
ンレス鋼に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving blade material for a steam turbine for driving a water supply pump for a nuclear power plant, and has a basic strength as a moving blade material and a wetness in a temperature range from room temperature to 200.degree. The present invention relates to a stainless steel having excellent pitting resistance in steam.
【０００２】[0002]
【従来の技術】従来、蒸気タービン用動翼材には、ＳＵ
Ｓ４１０、ＳＵＳ４０３等の１２％Ｃｒ系のマルテンサ
イト系ステンレス鋼が使用され、長い使用実績があるこ
とは周知のとおりである。2. Description of the Related Art Conventionally, moving blade materials for steam turbines include SU.
It is well known that 12% Cr-based martensitic stainless steel such as S410 and SUS403 is used and has a long track record of use.
【０００３】[0003]
【発明が解決しようとする課題】従来、使用されている
１２％Ｃｒ鋼では、限られた湿り蒸気（例えば、温度：
３０〜１７０℃，流体：蒸気，湿り度：３〜２０％）の
ような特別な条件で使用する場合に耐孔食性が必ずしも
十分でない場合もあり、耐孔食性のさらなる向上が望ま
れていた。一方、高強度でかつ耐食性の良好な材料とし
て、航空機用に使用される米国航空機材料規格（Ａｅｒ
ｏｓｐａｃｅ Ｍａｔｅｒｉａｌ Ｓｐｅｃｉｆｉｃａｔ
ｉｏｎ）のＡＭＳ５７６３鋼やＪＩＳ規格の１７−４Ｐ
Ｈ鋼、１５−５ＰＨ鋼、ＰＨ１３−８Ｍｏ鋼等の析出硬
化型ステンレス鋼が知られている。今回、高耐食性鋼と
して知られている上記のＡＭＳ５７６３鋼を９０℃、
３．５％ＮａＣｌ、ｐＨ７、溶存酸素（以下ＤＯと記
す)濃度 ２００ｐｐｂの環境中で５００ｈｒ浸漬試験し
てみた結果、耐孔食性は従来鋼である１２％Ｃｒ鋼と比
較して改善されたものの、まだ十分とは言えないことが
わかった。これまで、耐食性に優れた析出硬化型ステン
レス鋼としては、特開昭５４−７１０２５号や特開平０
１−１１９６４９号などの鋼が多数提案されている。Conventionally, the 12% Cr steel used has a limited wet steam (for example, temperature:
(30-170 ° C, fluid: steam, wetness: 3-20%), the pitting corrosion resistance may not always be sufficient when used under special conditions, and further improvement in pitting corrosion resistance has been desired. . On the other hand, as a material having high strength and good corrosion resistance, US Aircraft Material Standard (Aer
ospace Material Specificat
ion) AMS5763 steel and JIS standard 17-4P
Precipitation hardening stainless steels such as H steel, 15-5PH steel, and PH13-8Mo steel are known. This time, the above-mentioned AMS5763 steel known as high corrosion resistance steel was
As a result of a 500 hr immersion test in an environment of 3.5% NaCl, pH 7 and dissolved oxygen (hereinafter referred to as DO) 200 ppb, the pitting corrosion resistance was improved as compared with the conventional 12% Cr steel. , It turned out not to be enough. Until now, Japanese Patent Application Laid-Open No. 54-71025 and Japanese Patent Application Laid-Open
Many steels such as 1-119649 have been proposed.
【０００４】ところで、本発明のステンレス鋼が対象と
するような、蒸気タービン中の限られた条件での湿り蒸
気中で、耐孔食性を評価するためには、ほぼ中性でＤＯ
濃度をコントロールし、さらにｐＨ、温度等も制御した
環境で行なう必要がある。しかし特開昭５４−７１０２
５号に開示されているステンレス鋼は、孔食電位測定
（３０℃、３．５％ＮａＣｌ）によって耐孔食性を評価
しているのみで、本発明のように実環境に近い雰囲気で
の湿り蒸気中で浸漬試験を行なって評価しておらず、本
発明鋼のような蒸気タービンブレード用で使用できるか
どうか明らかではない。また特開平０１−１１９６４９
号に開示されているステンレス鋼は、沸騰５％硫酸液雰
囲気での腐食減量によって耐孔食性を評価しているのみ
で、本発明のような環境での耐孔食性の評価は行なって
おらず、蒸気タービンブレード用に使用できるかどうか
明らかではない。また、これらに開示されているステン
レス鋼には耐孔食性に有害な不純物の規定はなく、特開
平０１−１１９６４９号に一般論としてＰ、Ｓ、Ｏ、Ｈ
の総量を３５０ｐｐｍ以下が良いと述べているのにとど
まっている。Incidentally, in order to evaluate the pitting corrosion resistance in wet steam under limited conditions in a steam turbine, such as the target of the stainless steel of the present invention, an almost neutral DO
It is necessary to perform the treatment in an environment in which the concentration is controlled and the pH, temperature, and the like are also controlled. However, JP-A-54-7102
The stainless steel disclosed in No. 5 only evaluates the pitting corrosion resistance by pitting potential measurement (30 ° C., 3.5% NaCl), and has a wettability in an atmosphere close to a real environment as in the present invention. It has not been evaluated by performing an immersion test in steam, and it is not clear whether it can be used for a steam turbine blade such as the steel of the present invention. Japanese Patent Application Laid-Open No. 01-119649
In the stainless steel disclosed in the above publication, the pitting corrosion resistance was evaluated only by the loss of corrosion in a boiling 5% sulfuric acid solution atmosphere, but the pitting corrosion resistance in an environment such as the present invention was not evaluated. It is not clear if it can be used for steam turbine blades. Further, the stainless steels disclosed therein do not have any definition of impurities harmful to pitting corrosion resistance, and P, S, O, and H are generally described in JP-A-01-119649.
But only mentions that the total amount is preferably 350 ppm or less.
【０００５】以上のように原子力用給水ポンプ駆動用蒸
気タービンブレードのような湿り蒸気中で良好な耐孔食
性をもつステンレス鋼は従来見あたらなかった。本発明
の目的は、かかる点に鑑み、原子力用給水ポンプ駆動用
蒸気タービンのような湿り蒸気中で使用できるブレード
用ステンレス鋼を提供するものである。As described above, stainless steels having good pitting corrosion resistance in wet steam, such as steam turbine blades for driving a water feed pump for nuclear power, have not been found. In view of the above, an object of the present invention is to provide a stainless steel for blades that can be used in wet steam, such as a steam turbine for driving a water supply pump for nuclear power.
【０００６】[0006]
【課題を解決するための手段】本発明者は、耐孔食性を
改善すべく鋭意検討を行なった。その結果、特定の組成
を有するステンレス鋼において特に不純物であるＭｎ、
Ｓ、Ｏの量を規定量以下に低減させることによって、孔
食の起点となる非金属介在物（ＭｎＳ、Ａｌ2Ｏ3）を低
減することで、９０℃、３．５％ＮａＣｌ、ｐＨ７、２
００ｐｐｂＤＯ濃度の環境中で５００ｈｒ浸漬した後
の、孔食の深さが小さくなり、耐孔食性が大幅に改善さ
れることを新規に見出し、本発明に到ったものである。Means for Solving the Problems The present inventor has made intensive studies to improve pitting corrosion resistance. As a result, Mn, which is an impurity particularly in stainless steel having a specific composition,
Non-metallic inclusions (MnS, Al 2 O 3 ), which are the starting points of pitting corrosion, are reduced by reducing the amounts of S and O to a specified amount or less, so that 90 ° C., 3.5% NaCl, pH 7, 2
The present inventors have newly found that the depth of pitting corrosion after immersion for 500 hours in an environment having a concentration of 00 ppbDO is reduced and the pitting resistance is greatly improved, and the present invention has been achieved.
【０００７】すなわち、本発明の第１発明は、重量％
で、Ｃ：０．０５％以下、Ｓｉ：１．０％以下、Ｎｉ：
６．０〜７．０％、Ｃｒ：１４．０〜１６．０％、Ｍ
ｏ：０．５〜１．０％、Ｃｕ：１．２５〜１．７５％、
Ｎｂ：０．２０〜０．７５％、Ａｌ：０．００１〜０．
０５％を含み、残部が実質的にＦｅおよび不可避の不純
物よりなり、特にＭｎ、Ｓ、ＯをそれぞれＭｎ：０．２
％以下、Ｓ：０．００２％以下、Ｏ：０．００１５％以
下に制限したことを特徴とし、非金属介在物であるＭｎ
Ｓ、Ａｌ2Ｏ3を低減させたものである。また第２発明
は、９０℃、３．５％ＮａＣｌ、ｐＨ７、２００ｐｐｂ
ＤＯ濃度の環境中で、５００ｈｒ浸漬試験を行なった後
に発生する孔食ピットの最大深さを０．０１２μｍ以下
に制限したことを特徴とする耐孔食性に優れたブレード
用ステンレス鋼である。That is, the first invention of the present invention relates to
And C: 0.05% or less, Si: 1.0% or less, Ni:
6.0 to 7.0%, Cr: 14.0 to 16.0%, M
o: 0.5 to 1.0%, Cu: 1.25 to 1.75%,
Nb: 0.20 to 0.75%, Al: 0.001 to 0.
And Mn, S, and O, each containing Mn: 0.2%.
%, S: 0.002% or less, O: 0.0015% or less, and Mn which is a nonmetallic inclusion
S and Al 2 O 3 were reduced. Further, the second invention is at 90 ° C., 3.5% NaCl, pH 7, 200 ppb
A stainless steel for blades excellent in pitting corrosion resistance, characterized in that the maximum depth of pitting pits generated after performing a 500-hour immersion test in an environment of DO concentration is limited to 0.012 μm or less.
【０００８】[0008]
【発明の実施の形態】以下に本発明鋼の成分限定理由に
ついて述べる。最初に、本発明鋼に添加する合金元素の
限定理由について述べる。Ｃは、本発明の強度を確保す
るために必要なマルテンサイト組織を得るために必要な
元素であり、焼入性を確保するために、０．０３％は必
要であるが、０．０５％を超えて含有すると、Ｃｒ炭化
物が多く析出しＣｒ酸化皮膜の均一性が失われ、耐孔食
性が、劣化するので、０．０３〜０．０５％とした。Ｓ
ｉは、脱酸剤として少量添加するが、その含有量が多す
ぎる場合は、靭性が低下するので、１．０％以下とし
た。DESCRIPTION OF THE PREFERRED EMBODIMENTS The reasons for limiting the components of the steel of the present invention will be described below. First, the reasons for limiting the alloying elements added to the steel of the present invention will be described. C is an element necessary for obtaining a martensite structure required for securing the strength of the present invention, and 0.03% is required for securing hardenability, but 0.05% is required. If the content exceeds 0.1%, a large amount of Cr carbide precipitates, the uniformity of the Cr oxide film is lost, and the pitting corrosion resistance is deteriorated. S
i is added in a small amount as a deoxidizing agent, but if the content is too large, the toughness is reduced.
【０００９】Ｎｉは、耐孔食性、靭性を向上させ、また
高温でオーステナイトを安定化することでマルテンサイ
ト組織を得るのに必要な元素であるが、６．０％より少
ないと、δフェライトが生成し、耐孔食性を劣化させ
る。一方、７．０％を超えると、残留オーステナイト
が、安定化しすぎて強度が低下するので、Ｎｉは、６．
０〜７．０％とした。Ｃｒは、一般的な耐食性を向上さ
せるだけでなく、９０℃、３．５％ＮａＣｌ、ｐＨ７、
２００ｐｐｂＤＯ濃度の環境中での耐孔食性を向上させ
る最も重要な元素であり、本鋼の場合は、１４．０％以
上でその効果が、顕著になる。しかし同時にフェライト
形成元素でもあるので、その含有量が、１６．０％を超
えると、δフェライトが増加して強度、耐孔食性ともに
劣化する。したがってＣｒは、１４．０〜１６．０％と
した。Ni is an element necessary for obtaining a martensitic structure by improving pitting corrosion resistance and toughness and stabilizing austenite at a high temperature. It forms and deteriorates pitting corrosion resistance. On the other hand, if the content exceeds 7.0%, the retained austenite is excessively stabilized and the strength is reduced.
It was set to 0 to 7.0%. Cr not only improves general corrosion resistance, but also 90 ° C., 3.5% NaCl, pH 7,
It is the most important element for improving the pitting corrosion resistance in an environment having a concentration of 200 ppb DO. In the case of the present steel, its effect becomes remarkable at 14.0% or more. However, since it is also a ferrite-forming element, if its content exceeds 16.0%, δ ferrite increases and both strength and pitting corrosion resistance deteriorate. Therefore, Cr was set to 14.0 to 16.0%.
【００１０】Ｍｏは、Ｃｒと共に適量を必須添加するこ
とで、９０℃、３．５％ＮａＣｌ、ｐＨ７、２００ｐｐ
ｂＤＯ濃度の環境中での耐孔食性向上に非常に有効な元
素であるが、０．５％未満の添加量では、所望の効果が
得られない。一方、フェライト形成元素であるので、
１．０％を超えて含有させると、δフェライトが増加し
て強度、靭性さらに耐孔食性も劣化する。したがってＭ
ｏは、０．５〜１．０％とした。Ｃｕは、時効処理によ
って微細な析出物を形成し、本鋼における強度を高め
る。その含有量が、１．２５％より少ないと、所望の強
度が得られない。一方、その含有量が１．７５％を超え
ると、熱間加工性が低下するため、Ｃｕは、１．２５〜
１．７５％とした。Mo is added at 90 ° C., 3.5% NaCl, pH 7, 200 pp by adding an appropriate amount together with Cr.
Although it is a very effective element for improving pitting corrosion resistance in an environment having a bDO concentration, a desired effect cannot be obtained with an addition amount of less than 0.5%. On the other hand, since it is a ferrite forming element,
When the content exceeds 1.0%, δ ferrite increases and strength, toughness and pitting corrosion resistance are deteriorated. Therefore M
o was set to 0.5 to 1.0%. Cu forms fine precipitates by aging treatment and increases the strength of the steel. If the content is less than 1.25%, desired strength cannot be obtained. On the other hand, if the content exceeds 1.75%, the hot workability decreases, so that Cu is 1.25 to
1.75%.
【００１１】Ｎｂは、鋼中のＣをＮｂＣとして固定する
ことによって結晶粒界へのＣｒ炭化物の析出を抑制する
ことによって、９０℃、３．５％ＮａＣｌ、ｐＨ７、２
００ｐｐｂＤＯ濃度の環境中での耐孔食性の向上に有効
な元素であり、０．２０％未満ではその効果が不十分で
ある。一方、０．７５％を超えると、粗大なＮｂＣを形
成して熱間加工性を害するため、Ｎｂは、０．２０〜
０．７５％とした。Ａｌは、脱酸材として使用するため
０．００１％は必要であるが、その含有量が０．０５％
を超えると、造塊時に非金属介在物である酸化物（Ａｌ
2Ｏ3）を多く形成し、それを起点とする孔食が発生し、
耐孔食性が低下する。したがってＡｌは０．００１％〜
０．０５％とした。Nb is fixed at 90 ° C., 3.5% NaCl, pH 7, 2 by fixing C in steel as NbC to thereby suppress precipitation of Cr carbide at crystal grain boundaries.
It is an element effective for improving the pitting corrosion resistance in an environment having a concentration of 00 ppbDO, and if it is less than 0.20%, the effect is insufficient. On the other hand, if it exceeds 0.75%, coarse NbC is formed and hot workability is impaired.
0.75%. Since Al is used as a deoxidizing material, 0.001% is necessary, but the content is 0.05%.
Is exceeded, the oxide (Al
2 O 3 ), and pitting corrosion originating therefrom occurs,
The pitting resistance decreases. Therefore, Al is 0.001% or more.
0.05%.
【００１２】以下、本発明鋼の不純物元素の制限理由に
ついて述べる。Ｍｎは、Ｓｉと同様で、脱酸剤として少
量添加するが、０．２％を超えて含有すると、造塊時に
おいて非金属介在物である硫化物（ＭｎＳ）を形成する
ために、それが起点となって孔食が発生し、耐孔食性が
劣化し、また時効処理後に残留オーステナイトが、安定
化し強度が低下することから、０．２％以下とした。Ｓ
は、造塊時において非金属介在物である硫化物（Ｍｎ
Ｓ）を形成し、９０℃、３．５％ＮａＣｌ、ｐＨ７、２
００ｐｐｂＤＯ濃度の環境中においては、それを起点と
して孔食を発生し、耐孔食性や疲労強度が低下する。特
に耐孔食性に対しては、Ｓの量はなるべく低くした方が
よい。したがってその含有量は、０．００２％以下に限
定した。Hereinafter, the reasons for limiting the impurity elements of the steel of the present invention will be described. Similar to Si, Mn is added in a small amount as a deoxidizing agent. However, if it is contained in excess of 0.2%, sulfide (MnS), which is a nonmetallic inclusion, is formed at the time of agglomeration. Since it becomes a starting point, pitting corrosion occurs, pitting corrosion resistance is deteriorated, and retained austenite is stabilized after aging treatment, and strength is lowered. S
Is a sulfide (Mn
S), 90 ° C, 3.5% NaCl, pH 7,2
In an environment with a concentration of 00 ppbDO, pitting occurs starting from that, and pitting corrosion resistance and fatigue strength are reduced. In particular, for pitting corrosion resistance, the amount of S is preferably as low as possible. Therefore, its content is limited to 0.002% or less.
【００１３】Ｏは、Ａｌとともに造塊時において非金属
介在物である酸化物（Ａｌ2Ｏ3）を形成し、９０℃、
３．５％ＮａＣｌ、ｐＨ７、２００ｐｐｂＤＯ濃度の環
境中においてそれを起点として孔食が発生し、耐孔食性
や疲労強度が低下する。特に耐孔食性に対しては、Ｏの
量はなるべく低くした方がよい。そのためＯはなるべく
極低化させることが必要であり、０．００１５％以下に
限定した。なお、上記以外の元素に関しては、以下に示
す範囲内であれば、本発明鋼の特性が何らそこなわれる
ものではない。Ｐ：０．０３０％以下。O forms an oxide (Al 2 O 3 ) which is a nonmetallic inclusion at the time of agglomeration together with Al.
In an environment of 3.5% NaCl, pH 7, and 200 ppb DO concentration, pitting occurs from the starting point, and pitting resistance and fatigue strength are reduced. In particular, for pitting corrosion resistance, the amount of O is preferably as low as possible. Therefore, it is necessary to minimize O as much as possible, and it is limited to 0.0015% or less. The elements other than those described above do not impair the characteristics of the steel of the present invention at all within the following ranges. P: 0.030% or less.
【００１４】[0014]
【実施例】表１に本発明鋼、比較鋼（ＡＭＳ５７６３）
および従来鋼（１２％Ｃｒ鋼）の化学組成を示す。本発
明鋼は、非金属介在物であるＭｎＳおよびＡｌ2Ｏ3の低
減を狙いとして作製したものであり、低Ｍｎ量でさらに
Ｓ、Ｏの低減を狙いとしたトリプルメルト(大気溶解＋
エレクトロスラグ再溶解＋真空アーク再溶解)を行なっ
て造塊した。本発明鋼のＭｎ量、Ｓ量、Ｏ量は、それぞ
れ０．０４％、０．００１％、０．０００７％である。
試料は、溶解後、４０ｍｍ角の棒に熱間圧延した後、熱
処理を施した。熱処理は固溶化処理(１０４０℃×１Ｈ
ｒ，油冷)を施した後、２段時効処理(８１５℃×０．５
Ｈｒ，水冷＋５８５℃×５Ｈｒ、空冷)を行なった。次
に実環境に近い耐孔食性の評価試験として、浸漬試験を
行なった。EXAMPLES Table 1 shows the steels of the present invention and comparative steels (AMS5763).
And the chemical composition of conventional steel (12% Cr steel). The steel of the present invention was produced with the aim of reducing MnS and Al 2 O 3 , which are nonmetallic inclusions. Triple melt (atmospheric melting +
(Electro-slag re-melting + vacuum arc re-melting) was performed to form an ingot. The Mn content, S content, and O content of the steel of the present invention are 0.04%, 0.001%, and 0.0007%, respectively.
After melting, the sample was hot-rolled into a 40 mm square rod, and then subjected to heat treatment. Heat treatment is solution treatment (1040 ° C × 1H)
r, oil cooling), followed by two-stage aging treatment (815 ° C. × 0.5
Hr, water cooling + 585 ° C. × 5 Hr, air cooling). Next, an immersion test was performed as an evaluation test for pitting corrosion resistance close to the actual environment.
【００１５】[0015]
【表１】 [Table 1]
【００１６】この試験は、試験片（２ｍｍｔ×２０ｍｍ
ｗ×４０ｍｍＬ）を各試料につき２枚ずつ、ｐＨ７の
３．５％食塩水中に入れ、９０℃に加熱保持し、ＤＯ濃
度を２００ｐｐｂに制御して５００時間浸漬した。試験
後の試験片の孔食深さの測定については、光学顕微鏡を
用いて計測した。試験片の表面を１ｃｍ角の区画に分け
るようにケガキを行ない、各１ｃｍ角の区画の中で最も
大きいピットについてその深さを焦点深度法(試料表面
とピット底のピントのずれから、試料台の上下方向の変
位をダイヤルゲージより測定)によって測定した。この
測定は、１つの試験片当たり、試験片表面の両面合わせ
て計１６個所(区画)について行ない、試験した２枚ずつ
について行なった。In this test, a test piece (2 mmt × 20 mm
(w.times.40 mmL) were placed in a 3.5% saline solution having a pH of 7 for each sample, heated and maintained at 90.degree. C., and immersed for 500 hours while controlling the DO concentration at 200 ppb. About the measurement of the pit depth of the test piece after a test, it measured using the optical microscope. The surface of the test piece is marked so as to be divided into 1-cm square sections, and the depth of the largest pit in each 1-cm square section is determined by the depth of focus method. Was measured from a dial gauge). This measurement was carried out for a total of 16 places (compartments) for each test piece, including both surfaces of the test piece, and for each of the two test pieces.
【００１７】[0017]
【表２】 [Table 2]
【００１８】表２に本発明鋼、比較鋼（ＡＭＳ５７６
３）の非金属介在物（ＭｎＳ、Ａｌ2Ｏ3）量の測定結果
を示す。表２から、本発明鋼は比較鋼と比べると、合計
で１ｍｍ2あたり２．０５個から０．６６個と約６７％
減少しており、不純物であるＭｎ、Ｓ、Ｏを低減させた
ことによる非金属介在物（ＭｎＳ、Ａｌ2Ｏ3）低減の効
果が認められる。また、表３に浸漬試験を行なった後の
試料の孔食ピットの最大深さの実測値を示す。表３か
ら、本発明鋼の孔食深さは従来鋼である１２％Ｃｒ鋼お
よび比較鋼ＡＭＳ５７６３鋼と比較して大きく減少し、
耐孔食性は著しく改善されており、不純物であるＭｎ、
Ｓ、Ｏを低減し、耐孔食性に有害な非金属介在物を低減
させた効果が明らかであることがわかる。Table 2 shows the steels of the present invention and comparative steels (AMS576).
The measurement result of the amount of nonmetallic inclusions (MnS, Al 2 O 3 ) of 3 ) is shown. Table 2 shows that the steel of the present invention has a total of 2.05 to 0.66 per 1 mm 2 , which is about 67% of that of the comparative steel.
The effect of reducing nonmetallic inclusions (MnS, Al 2 O 3 ) by reducing the impurities Mn, S, and O is recognized. Table 3 shows the measured values of the maximum depth of the pits of the sample after the immersion test. From Table 3, the pit depth of the steel of the present invention is significantly reduced as compared with the conventional steel of 12% Cr steel and the comparative steel AMS5763 steel,
The pitting resistance has been significantly improved, and the impurities Mn,
It can be seen that the effect of reducing S and O and reducing nonmetallic inclusions harmful to pitting corrosion resistance is obvious.
【００１９】[0019]
【表３】 [Table 3]
【００２０】[0020]
【発明の効果】本発明鋼を原子力用給水ポンプ用蒸気タ
ービン用ブレード材のような湿り蒸気中で用いる部材に
使用すれば、耐孔食性が大幅に向上し、部材の寿命向上
に大きく寄与できるものであり、工業上顕著な効果を有
するものである。When the steel of the present invention is used for a member used in wet steam, such as a blade material for a steam turbine for a water feed pump for nuclear power, the pitting corrosion resistance is greatly improved, and the life of the member can be greatly improved. And has an industrially significant effect.
Claims (2)
Ｓｉ：１．０％以下、 Ｎｉ：６．０〜７．０％、Ｃ
ｒ：１４．０〜１６．０％、Ｍｏ：０．５〜１．０％、
Ｃｕ：１．２５〜１．７５％、Ｎｂ：０．２０〜０．７
５％、Ａｌ：０．００１〜０．０５％を含み、残部が実
質的にＦｅおよび不可避の不純物よりなり、特に不純物
であるＭｎとＳとＯをそれぞれＭｎ：０．２％以下、
Ｓ：０．００２％以下、Ｏ：０．００１５％以下に制限
したことを特徴とする耐孔食性に優れた蒸気タービンブ
レード用ステンレス鋼。C .: 0.03 to 0.05% by weight,
Si: 1.0% or less, Ni: 6.0 to 7.0%, C
r: 14.0 to 16.0%, Mo: 0.5 to 1.0%,
Cu: 1.25 to 1.75%, Nb: 0.20 to 0.7
5%, Al: 0.001 to 0.05%, the balance being substantially composed of Fe and unavoidable impurities. Particularly, impurities Mn, S, and O are each Mn: 0.2% or less.
S: 0.002% or less, O: 0.0015% or less, stainless steel for steam turbine blades excellent in pitting corrosion resistance, characterized in that:
存酸素濃度２００ｐｐｂの環境中で、５００ｈｒの浸漬
試験を行なった後に発生する１ｃｍ2当りの孔食の最大
深さが０．０１２μｍ以下であることを特徴とする特許
請求項の範囲第１項に記載の耐孔食性に優れた蒸気ター
ビンブレード用ステンレス鋼。2. The maximum depth of pitting corrosion per 1 cm 2 generated after performing an immersion test for 500 hours in an environment of 90 ° C., 3.5% NaCl, pH 7, and a dissolved oxygen concentration of 200 ppb is 0.012 μm or less. The stainless steel for a steam turbine blade excellent in pitting corrosion resistance according to claim 1, characterized in that:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17437896A JPH108217A (en) | 1996-06-14 | 1996-06-14 | Stainless steel for steam turbine blade, excellent in pitting corrosion resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17437896A JPH108217A (en) | 1996-06-14 | 1996-06-14 | Stainless steel for steam turbine blade, excellent in pitting corrosion resistance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH108217A true JPH108217A (en) | 1998-01-13 |
Family
ID=15977575
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17437896A Pending JPH108217A (en) | 1996-06-14 | 1996-06-14 | Stainless steel for steam turbine blade, excellent in pitting corrosion resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH108217A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000204447A (en) * | 1999-01-08 | 2000-07-25 | Hitachi Ltd | High strength martensitic steel, turbine disk for gas turbine using the same, gas turbine for power generation and combined power generating system |
| JP2003301235A (en) * | 2002-03-28 | 2003-10-24 | General Electric Co <Ge> | Fabrication of high tensile strength steel article with inclusion control during melting |
| JP2008127613A (en) * | 2006-11-20 | 2008-06-05 | Hitachi Ltd | Precipitation-hardened martensitic stainless steel |
| JP2015532695A (en) * | 2012-07-30 | 2015-11-12 | ゼネラル・エレクトリック・カンパニイ | Metal leading edge protective strip, corresponding airfoil and manufacturing method |
| CN105886949A (en) * | 2016-04-14 | 2016-08-24 | 四川六合锻造股份有限公司 | High-performance heat resistant steel, and preparation method and application thereof |
| US20220341013A1 (en) * | 2021-04-27 | 2022-10-27 | General Electric Company | Precipitation-hardened stainless steel alloys |
-
1996
- 1996-06-14 JP JP17437896A patent/JPH108217A/en active Pending
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000204447A (en) * | 1999-01-08 | 2000-07-25 | Hitachi Ltd | High strength martensitic steel, turbine disk for gas turbine using the same, gas turbine for power generation and combined power generating system |
| JP2003301235A (en) * | 2002-03-28 | 2003-10-24 | General Electric Co <Ge> | Fabrication of high tensile strength steel article with inclusion control during melting |
| JP4640909B2 (en) * | 2002-03-28 | 2011-03-02 | ゼネラル・エレクトリック・カンパニイ | Production of high-strength steel articles by controlling inclusions during melting |
| JP2008127613A (en) * | 2006-11-20 | 2008-06-05 | Hitachi Ltd | Precipitation-hardened martensitic stainless steel |
| JP4702267B2 (en) * | 2006-11-20 | 2011-06-15 | 株式会社日立製作所 | Precipitation hardening type martensitic stainless steel |
| JP2015532695A (en) * | 2012-07-30 | 2015-11-12 | ゼネラル・エレクトリック・カンパニイ | Metal leading edge protective strip, corresponding airfoil and manufacturing method |
| CN105886949A (en) * | 2016-04-14 | 2016-08-24 | 四川六合锻造股份有限公司 | High-performance heat resistant steel, and preparation method and application thereof |
| US20220341013A1 (en) * | 2021-04-27 | 2022-10-27 | General Electric Company | Precipitation-hardened stainless steel alloys |
| EP4083250A1 (en) * | 2021-04-27 | 2022-11-02 | General Electric Company | Precipitation-hardened stainless steel alloys |
| US11788177B2 (en) | 2021-04-27 | 2023-10-17 | General Electric Company | Precipitation-hardened stainless steel alloys |
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