JPS59110723A - Preparation of 12% cr type cast steel product - Google Patents
Preparation of 12% cr type cast steel productInfo
- Publication number
- JPS59110723A JPS59110723A JP21926182A JP21926182A JPS59110723A JP S59110723 A JPS59110723 A JP S59110723A JP 21926182 A JP21926182 A JP 21926182A JP 21926182 A JP21926182 A JP 21926182A JP S59110723 A JPS59110723 A JP S59110723A
- Authority
- JP
- Japan
- Prior art keywords
- cast steel
- creep
- steel product
- type cast
- subjected
- 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.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】
〔発明の技術分野〕
この発明は蒸気タービンのケーシング、パルプケーシン
グ、ノズルボックス等として用いられる12%Cr系鋳
鋼の欠陥部補修溶接により劣化した材料特性を回復させ
る12%Cr系鋳鋼品の製造方法に関する。[Detailed Description of the Invention] [Technical Field of the Invention] This invention is a 12% Cr-based cast steel used for steam turbine casings, pulp casings, nozzle boxes, etc., which recovers deteriorated material properties by repairing defective parts and welding them. The present invention relates to a method for manufacturing Cr-based cast steel products.
現在ケーシング、バルブケーシング、ノズルボックスな
どの蒸気タービン部品にはI Cr −IMo −0,
25V鋳鋼が使用されているが、今後熱効率アップを目
的とした高温、高圧タービンを自相した場合、従来の低
合金鋳鋼では高温強度が不足する。Currently, steam turbine parts such as casings, valve casings, and nozzle boxes contain I Cr -IMo -0,
25V cast steel is used, but if a high-temperature, high-pressure turbine is built in the future to improve thermal efficiency, conventional low-alloy cast steel will lack high-temperature strength.
そこで、更に高温特性のすぐれている12%Cr系鋳鋼
の使用が考えられている。しかし、高温で優れたクリー
プ強度を示す材料には、それと相反する性質としてクリ
ープき裂伝播速度の加速という欠点があり、このクリー
プき裂伝播速度の加速は、ケーシング材料の破壊寿命を
大幅に低下させる。Therefore, the use of 12% Cr cast steel, which has even better high-temperature properties, is being considered. However, materials that exhibit excellent creep strength at high temperatures have the contradictory property of accelerating the creep crack propagation rate, and this acceleration of the creep crack propagation rate significantly reduces the fracture life of the casing material. let
このため、高温化に対処できるケーシング材料としては
優れたクリープ強度に加えて、遅いクリープき裂伝播速
度をも兼ね備えることが要求される。Therefore, a casing material that can cope with high temperatures is required to have not only excellent creep strength but also a slow creep crack propagation speed.
度で歪取り焼鈍を行なった後で使用している。この補修
溶接を行なったケーシングは補修溶接に伴なう加熱によ
り溶接部および熱影響部の焼入れ作用や焼なまし作用な
どに起因して、補修溶接部および熱影響部の材料特性の
劣化、たとえば高温クリープ強度の低下やクリープき裂
伝播速度の加速を生ずる。この部分に、もしピンホール
や非金属介在物などが存在した場合には、蒸気タービン
の動作時にケーシングの補修溶接部あるいは熱影響部に
き裂を生じ、このき裂が動作時間の経過とともに伝播し
て大きな割れとなったり、極端寿場合には破壊にまで至
る。It is used after being subjected to strain relief annealing at a high temperature. The casing that has undergone this repair welding will suffer from deterioration of the material properties of the repair weld and heat affected zone due to the quenching and annealing effects of the weld and heat affected zone due to the heating associated with repair welding, such as deterioration of the material properties of the repair weld and heat affected zone. This causes a decrease in high-temperature creep strength and an acceleration of creep crack propagation speed. If there are pinholes or nonmetallic inclusions in this part, cracks will occur in the repair welds or heat affected zone of the casing during operation of the steam turbine, and these cracks will propagate over time. This can lead to large cracks, or even destruction in extreme cases.
この補修溶接部および熱影響部の材料特性の劣化は高温
特性、たとえば高温クリープ強度や熱疲労強度の擾れた
12%’Cr系鋳鋼においても例外とは言えない。This deterioration of the material properties of repair welds and heat-affected zones is no exception even in 12%'Cr cast steel, which has deteriorated high-temperature properties, such as high-temperature creep strength and thermal fatigue strength.
たとえば、溶接部および溶接部にごく近い熱影響部は補
修溶接後の冷却過程で焼入れされ、高温クリープ強度が
上昇する反面、クリープき裂伝播速度が速く外る。For example, the weld and the heat-affected zone very close to the weld are quenched during the cooling process after repair welding, increasing the high-temperature creep strength but increasing the creep crack propagation speed.
一方、溶接部から遠い熱影響部は補修溶接に伴なう加熱
により、焼なましされ高温クリープ強度が大幅に低下す
る。On the other hand, the heat-affected zone far from the weld is annealed by the heating associated with repair welding, and its high-temperature creep strength is significantly reduced.
本発明は以上の点を考慮してなされたもので、蒸気ター
ビンのケーシング、パルプケーシング、ノズルボックス
等に用いられる12%Cr系鋳鋼の欠陥部補修溶接によ
り劣化した材料特性を回復させる、すなわち高温におい
て優れたクリープ強度および遅いクリープき裂伝播速度
を兼ね備えさせる12%Cr系鋳鋼品の製造方法を提供
することを目的とする。The present invention has been made in consideration of the above points, and is intended to restore deteriorated material properties by repairing defective parts of 12% Cr cast steel used for steam turbine casings, pulp casings, nozzle boxes, etc. An object of the present invention is to provide a method for producing a 12% Cr cast steel product that has both excellent creep strength and slow creep crack propagation speed.
本発明に係る12%Cr系鋳鋼品の製造方法は、12%
Cr系鋳鋼品を製造する工程において、欠陥部を補修溶
接した後、1020℃〜1080℃でオーステナイト化
処理した後焼入れ、つづいて焼戻しすることを特徴とし
ている。もちろん、大型鋳鋼品の場合、補修溶接後、応
力除去焼鈍や焼なましをすることは通常行なわれている
ことである。The method for manufacturing a 12% Cr-based cast steel product according to the present invention includes
In the process of manufacturing Cr-based cast steel products, after repair welding of defective parts, austenitizing treatment is performed at 1020°C to 1080°C, followed by quenching, followed by tempering. Of course, in the case of large cast steel products, stress relief annealing or annealing is normally performed after repair welding.
本発明に係る12%Cr系鋳鋼品の製造方法は、欠陥部
補修溶接によって出来た溶接部および溶接部にごく近い
熱影響部の高温クリープ強度の上昇とクリープき裂伝播
速度の加速を、また溶接部よりはなれた熱影響部のクリ
ープ強度の低下を補修溶接後に限定した熱処理温度範囲
にて焼入れ処理を行寿うことによって改善し、高温での
クリープ強度を低下させることなく、クリープき裂伝播
速度を遅くすることを究明してなされたものである。The method for manufacturing 12% Cr-based cast steel products according to the present invention increases the high-temperature creep strength and accelerates the creep crack propagation rate of the welded zone created by defect repair welding and the heat-affected zone very close to the welded zone. The decrease in creep strength in the heat-affected zone away from the weld can be improved by performing quenching treatment within a limited heat treatment temperature range after repair welding, thereby preventing creep crack propagation without decreasing creep strength at high temperatures. This was done after researching how to slow down the speed.
ここで、本発明に係る12%Cr系鋳鋼の限定した熱処
理温度の範囲について説明すると、補修溶接後の熱処理
は、溶接部および熱影響部を完全なオーステナイト組織
番こするための温度で、合金の固溶体強化と析出強化を
充分発揮でき、高温で優れたクリープ強度と遅いクリー
プき裂伝播速度を兼備させるに必要な温度範囲で、10
80℃を越えると熱処理時にCr 、 Mo 、 y
、 NbなどとC,Nが化合した炭窒化物の析出量が増
加し、クリープ強度を高める反面、結晶粒の粗大化とと
もに、これがクリープ延性を低下させることとまるため
、蒸気タービンケーシングとして使用した場合、補修溶
接部に発生した割れ先端の応力緩和とクリープ変形を難
しくシ、クリープき裂伝播速度を加速させ、また、10
20℃未満の熱処理温度は、炭窒化物な十分に固溶させ
たオーステナイト組織をつくることができないため、未
固溶の合金元素が補修溶接した後での熱処理合金中に塊
状として残留したり、固溶体強化と析出強化が充分発揮
でき々いため高温でのクリープ強度を大幅に低下させる
のでこの範囲とする。Here, to explain the limited heat treatment temperature range of the 12% Cr cast steel according to the present invention, the heat treatment after repair welding is performed at a temperature to completely remove the austenitic structure of the weld zone and heat-affected zone. 10 in the temperature range necessary to fully exhibit solid solution strengthening and precipitation strengthening, and to have both excellent creep strength and slow creep crack propagation speed at high temperatures.
When the temperature exceeds 80℃, Cr, Mo, y
When used as a steam turbine casing, the amount of precipitated carbonitrides, which are a combination of Nb, etc., and C and N, increases and increases the creep strength, but on the other hand, the crystal grains become coarser and this decreases the creep ductility. , it makes stress relaxation and creep deformation at the tip of the crack that occurred in the repair weld difficult, accelerates the creep crack propagation speed, and
At a heat treatment temperature of less than 20°C, it is not possible to create an austenite structure in which carbonitrides are sufficiently dissolved, so that alloying elements that are not dissolved in solid solution may remain as lumps in the heat treated alloy after repair welding. Since solid solution strengthening and precipitation strengthening cannot be fully exerted, the creep strength at high temperatures is significantly reduced, so this range is set.
以上説明したように本発明によれば、蒸気タービン用の
ケーシング、バルブケーシング、ノズルボックス等の補
修溶接に伴寿う溶接部および熱影響部の材料特性の劣化
した12%Cr系鋳鋼に、限定した温度範囲での熱処理
を施すことにより、溶接部の高温クリープ強度を高め、
かつクリープき裂伝播速度を遅くすることが出来る。As explained above, according to the present invention, 12% Cr cast steel is limited to 12% Cr cast steel, which has deteriorated material properties in welded parts and heat affected zones that accompany repair welding of steam turbine casings, valve casings, nozzle boxes, etc. By applying heat treatment in the specified temperature range, the high-temperature creep strength of the weld is increased,
In addition, the creep crack propagation speed can be slowed down.
このため12%Cr系鋳鋼品の破壊寿命を大幅に伸ばし
、かつ長時間安全に使用でき、運転効率と信頼性を大幅
に向上できる効果がある。Therefore, the fracture life of 12% Cr-based cast steel products can be greatly extended, and they can be used safely for long periods of time, and their operating efficiency and reliability can be greatly improved.
さらに、本発明に係る12%Cr系鋳鍋品を使用するこ
とによって蒸気温度を上げてタービン熱効率を向上させ
ることも可能となり工業上類る有用である。Furthermore, by using the 12% Cr-based cast pot product according to the present invention, it is possible to increase the steam temperature and improve the turbine thermal efficiency, which is of similar industrial utility.
高周波真空誘導溶解炉を用いて第1表に示す化学組成の
12%Cr鋼素体を溶解、鋳造した。鋳造した12%C
r鋳鋼素体には一般に行なわれる焼入れ、焼戻し処理と
して1050℃4時間加熱後焼入れ725℃で4時間加
熱後焼戻し処理を処した。A 12% Cr steel body having the chemical composition shown in Table 1 was melted and cast using a high frequency vacuum induction melting furnace. Cast 12%C
rThe cast steel body was subjected to a quenching and tempering process that is generally performed at 1050°C for 4 hours, then quenching, then heated at 725°C for 4 hours, and then tempered.
第 1 表
次に上記焼入れ、焼戻し処理を行なった12%Cr鋳鋼
素体より試験素材を2個切り出し、1個について補修溶
接に伴なう熱影響部の加熱温度に相当する代表的温度と
して1150℃と1000℃の2種の温度で1時間加熱
後焼入れし次いで600℃で4時間の歪取り焼鈍を行な
った。この熱処理を行なった試験素材をそれぞれ115
0’O−A処理材、1000℃−A処理材とする。Table 1 Next, two test materials were cut out from the 12% Cr cast steel body that had undergone the above-mentioned quenching and tempering treatment, and each test material was heated to 1150°C as a representative temperature corresponding to the heating temperature of the heat-affected zone during repair welding. After heating at two temperatures of 1000°C and 1000°C, quenching was performed, followed by strain relief annealing at 600°C for 4 hours. Each of the test materials subjected to this heat treatment was 115
0'O-A treated material and 1000°C-A treated material.
また、他の1個について、補修溶接に伴なう熱影響部の
加熱温度に相当する代表的温度として1150℃と10
00℃の2種の温度で1時間加熱後、焼入れしつづいて
725°Cの温度で4時間焼戻しを行なった。この熱処
理を行なった試験素材をそれぞれ1150℃−B処理材
、1000″O−B処理材とする。In addition, for the other one, the representative temperatures corresponding to the heating temperature of the heat affected zone accompanying repair welding were 1150℃ and 10℃.
After heating at two temperatures of 00°C for 1 hour, quenching was continued, followed by tempering at a temperature of 725°C for 4 hours. The test materials subjected to this heat treatment are referred to as a 1150°C-B treated material and a 1000'' O-B treated material, respectively.
次にこれら準備したB処理材をそれぞれ4分割し、4個
のB処理材に対して1150℃、1100°01105
0°Cおよび1000℃で4時間加熱後、焼入れ、つづ
いて725°Cで約4時間加熱後焼戻し処理した。この
熱処理を行なった試験素材をそれぞれ1150℃−C処
理材、1100℃−C処理材、1050℃−C処理材お
よび1000℃−C処理材とする。Next, each of these prepared B-treated materials was divided into four parts, and the four B-treated materials were heated at 1150°C and 1100°01105.
After heating at 0°C and 1000°C for 4 hours, quenching was performed, followed by heating at 725°C for about 4 hours and tempering. The test materials subjected to this heat treatment are referred to as a 1150°C-C treated material, a 1100°C-C treated material, a 1050°C-C treated material, and a 1000°C-C treated material.
以上のAおよびC処理材からクリープ試験片およびクリ
ープき裂伝播試験用CT試験片を作成し、それぞれ試験
を行なった。Creep test pieces and CT test pieces for creep crack propagation tests were prepared from the above A and C treated materials, and tests were conducted on each.
これらの試験結果を第2表に示す。The results of these tests are shown in Table 2.
・以7:グR
第2表より明らかなように、本発明に係る12%Cr系
鋳鋼品はC処理におけるオーステナイト化温度の高いも
のtなど高いクリープ破断強度を示している。しかし、
クリープき裂伝播速度はC処理におけるオーステナイト
化温度の高いものほど早いクリープき裂伝播速度を示し
、本発明に係る1050”Q−C処理を行なった12%
Cr鋳鋼は、1100℃−C処理を行なった比較例3、
あるいは比較例7に比べ約8.5〜4倍遅い、また11
50℃−C処理を行なった比較例2あるいは比較例6に
比べ約8倍遅いクリープき裂伝播速度を、すガわち、そ
れぞれ約8.5〜4倍あるいは約8倍の破壊寿命を示し
ている。- 7: G R As is clear from Table 2, the 12% Cr cast steel products according to the present invention exhibit high creep rupture strength, such as those with a high austenitizing temperature in C treatment. but,
The higher the austenitization temperature in the C treatment, the faster the creep crack propagation rate, and the 1050"Q-C treatment according to the present invention showed a faster creep crack propagation rate.
Cr cast steel was Comparative Example 3, which was subjected to 1100°C-C treatment.
Or about 8.5 to 4 times slower than Comparative Example 7, and 11
The creep crack propagation velocity was about 8 times slower than that of Comparative Example 2 or Comparative Example 6, which were treated at 50° C.-C, and the fracture life was about 8.5 to 4 times or about 8 times longer, respectively. ing.
また、従来のlCr−lMo−0,25V鋳鋼品におい
て行なわれていた1150℃−入処理を行なった比較例
1では高温クリープ強度は高いが、クリープき裂伝播速
度が約5.5倍早<、1000℃−入処理を行なった比
較例5では高温クリープ強度が約1/2となっている。In addition, in Comparative Example 1, which was subjected to the 1150°C heating treatment that was performed on conventional lCr-lMo-0,25V cast steel products, the high temperature creep strength was high, but the creep crack propagation rate was about 5.5 times faster. In Comparative Example 5, which was subjected to the heating treatment at 1000°C, the high temperature creep strength was approximately 1/2.
このように本発明に係る12%Cr系鋳鋼品を製造する
工程において、欠陥部を補修溶接後に、限定した温度範
囲でオーステナイト化処理した後、焼入れ、つづいて焼
戻し処理を行なった(本発明例1.2)合金においては
、他の熱処理を行なった(比較例1〜8)合金に比べは
るかに優れたクリープ破断強度を持ち、かつクリープ破
断強度を低下させることなく遅いクリープき裂伝播速度
を持つことが確認できた。In this way, in the process of manufacturing the 12% Cr-based cast steel product according to the present invention, after repair welding of defective parts, austenitizing treatment was performed in a limited temperature range, followed by quenching, followed by tempering treatment (inventive example 1.2) The alloy has far superior creep rupture strength compared to alloys that have undergone other heat treatments (Comparative Examples 1 to 8), and has a slow creep crack propagation rate without reducing the creep rupture strength. I was able to confirm that I have it.
代理人 弁理士 則 近 憲 佑 (にか1名)112
−Agent Patent Attorney Kensuke Chika (1 person) 112
−
Claims (1)
補修溶接した後、 1020℃〜1080″Cでオー
ステナイト化処理した後焼入れ、つづいて、焼戻しする
ことを特徴とする12%Cr系鋳鋼品の製造方法。A 12% Cr cast steel product characterized in that, in the process of manufacturing a 12% Cr cast steel product, defective parts are repaired and welded, then austenitized at 1020°C to 1080″C, then quenched, and then tempered. manufacturing method.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP21926182A JPS59110723A (en) | 1982-12-16 | 1982-12-16 | Preparation of 12% cr type cast steel product |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP21926182A JPS59110723A (en) | 1982-12-16 | 1982-12-16 | Preparation of 12% cr type cast steel product |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS59110723A true JPS59110723A (en) | 1984-06-26 |
JPH0453928B2 JPH0453928B2 (en) | 1992-08-28 |
Family
ID=16732746
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP21926182A Granted JPS59110723A (en) | 1982-12-16 | 1982-12-16 | Preparation of 12% cr type cast steel product |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS59110723A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63176434A (en) * | 1987-01-14 | 1988-07-20 | Babcock Hitachi Kk | Heat treatment for welding zone |
USRE37562E1 (en) | 1988-05-05 | 2002-02-26 | Siemens Westinghouse Power Corporation | Turbine system having more failure resistant rotors and repair welding of low alloy ferrous turbine components by controlled weld build-up |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5779149A (en) * | 1980-11-05 | 1982-05-18 | Toshiba Corp | Steam turbine rotor for geothermal generation of electric power and its manufacture |
-
1982
- 1982-12-16 JP JP21926182A patent/JPS59110723A/en active Granted
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5779149A (en) * | 1980-11-05 | 1982-05-18 | Toshiba Corp | Steam turbine rotor for geothermal generation of electric power and its manufacture |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS63176434A (en) * | 1987-01-14 | 1988-07-20 | Babcock Hitachi Kk | Heat treatment for welding zone |
USRE37562E1 (en) | 1988-05-05 | 2002-02-26 | Siemens Westinghouse Power Corporation | Turbine system having more failure resistant rotors and repair welding of low alloy ferrous turbine components by controlled weld build-up |
Also Published As
Publication number | Publication date |
---|---|
JPH0453928B2 (en) | 1992-08-28 |
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