JPH10121188A - Low chromium ferritic cast steel excellent in high temperature strength and weldability - Google Patents
Low chromium ferritic cast steel excellent in high temperature strength and weldabilityInfo
- Publication number
- JPH10121188A JPH10121188A JP8268529A JP26852996A JPH10121188A JP H10121188 A JPH10121188 A JP H10121188A JP 8268529 A JP8268529 A JP 8268529A JP 26852996 A JP26852996 A JP 26852996A JP H10121188 A JPH10121188 A JP H10121188A
- Authority
- JP
- Japan
- Prior art keywords
- cast steel
- weldability
- steel
- strength
- less
- 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.)
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は高温強度が高く、溶
接性、耐酸化性および高温耐食性に優れ、ボイラ、原子
力、化学工業などの分野で、特に４５０℃以上の高温環
境下で使用される鋳造用材料として好適な低Ｃｒフェラ
イト鋳鋼に関する。TECHNICAL FIELD The present invention has high strength at high temperatures, excellent weldability, oxidation resistance and high-temperature corrosion resistance, and is used in the fields of boilers, nuclear power plants, chemical industries, etc., particularly in a high-temperature environment of 450 ° C. or higher. The present invention relates to a low Cr ferritic cast steel suitable as a casting material.
【０００２】[0002]
【従来の技術】ボイラ、原子力、化学工業などの各種の
機器で高温耐熱耐圧部品に使用される材料としては、オ
ーステナイト鋼、９〜１２％Ｃｒ系高Ｃｒフェライト
鋼、２・１／４Ｃｒ−１Ｍｏ鋼を含む３．５％以下の低
Ｃｒフェライト鋼、炭素鋼が用いられている。これらは
対象部材の使用温度、圧力使用雰囲気などに応じて、か
つ経済性を考慮して適宜、選択されている。なかでも、
９〜１２％Ｃｒおよび３．５％Ｃｒ以下の低Ｃｒフェラ
イト鋼に関しては、さまざまな微量元素を添加した成分
系が研究され、その結果、フェライト鋼においてもオー
ステナイト鋼と同等以上の高温強度をもつ材料も開発さ
れてきた。しかし、多くのものは、鍛造圧廷など、加工
を施して使用することが前提にされており、鋳鋼のよう
に鍛造圧廷なしに使用する鋼に関するものは非常に少な
い。それは、高温強度、溶接性、衝撃特性、経済性な
ど、トータルに性能を兼ね備えた材料の開発が困難であ
ったためだと思われる。2. Description of the Related Art Austenitic steel, 9-12% Cr-based high Cr ferritic steel, 2.1 / 4 Cr-1 Mo are used as materials for high-temperature and heat-resistant components in various devices such as boilers, nuclear power plants and chemical industries. 3.5% or less low Cr ferritic steel and carbon steel including steel are used. These are appropriately selected according to the use temperature, the pressure use atmosphere, and the like of the target member and in consideration of economy. Above all,
For low Cr ferritic steels of 9 to 12% Cr and 3.5% Cr or less, component systems to which various trace elements are added have been studied. As a result, even ferritic steels have a high temperature strength equal to or higher than that of austenitic steels. Materials have also been developed. However, it is presumed that many of them are used after being processed, such as forging, and there are very few steels that are used without forging, such as cast steel. This is probably because it was difficult to develop a material that combines high performance such as high-temperature strength, weldability, impact properties, and economy.
【０００３】鋳鋼には鍛鋼と比較して、鍛造工程なし
に、複雑な形状のものを容易に成形でき、そのため加工
費が安くなるという大きな利点を有している。近年の鋳
造技術の進歩により従来危惧されていた鋳鋼の信頼性は
著しく向上しており、安価で高温強度と溶接性に優れた
鋳鋼が望まれている。[0003] Compared with forged steel, cast steel has a great advantage that a complicated shape can be easily formed without a forging step, and therefore the processing cost is reduced. Due to recent advances in casting technology, the reliability of cast steel, which has been a concern in the past, has been significantly improved, and cast steel that is inexpensive and has excellent high-temperature strength and weldability is desired.
【０００４】[0004]
【発明が解決しようとする課題】前述したように既存の
添加Ｃｒフェライト鋳鋼の問題点としては、低Ｃｒフ
ェライト鋳鋼においては、特に厚肉材においてポロシテ
イや高温割れの発生による材料劣化を生ずる。４５０
℃以上での高温クリープ強度が低い。衝撃特性が劣っ
ている。溶接時には予熱を必要とするという問題点を
有している。そこで、本発明は厚肉鋳鋼でも鋳造欠陥が
なく、４５０℃以上の温度における高温強度、特に高温
クリープ強度を従来の鋳鋼に比べ大幅に改善すると共
に、靱性、溶接性においても既存の鍛鋼と同等以上の性
能を有する経済性に優れた低Ｃｒフェライト鋳鋼を提供
しようとするものである。As described above, the problem of the existing Cr-added ferrite cast steel is that, in the case of low-Cr ferrite cast steel, material deterioration occurs due to occurrence of porosity and high-temperature cracking, especially in thick materials. 450
Low high temperature creep strength above ℃. Poor impact properties. There is a problem that preheating is required at the time of welding. Therefore, the present invention has no casting defects even in thick cast steel, and significantly improves high-temperature strength at a temperature of 450 ° C. or higher, especially high-temperature creep strength, as compared with conventional cast steel, and has the same toughness and weldability as existing forged steel. It is an object of the present invention to provide a low Cr ferritic cast steel having the above performance and excellent in economy.
【０００５】[0005]
【課題を解決するための手段】本発明者らは厚肉の鋳
鋼でも内部欠陥を抑えること、ＶとＮｂによる析出効
果と、Ｗ，Ｍｏ，Ｃｕによる固溶強化により４５０℃以
上のクリープ強度を高めること及びＣ，ＭｎおよびＢ
の添加量の制御により溶接性を改善させることの基本的
な考え方で上記課題を解決することに取り組み、つぎの
知見を得た。Means for Solving the Problems The present inventors can suppress internal defects even in thick cast steel, increase the precipitation effect of V and Nb, and increase the creep strength of 450 ° C. or more by solid solution strengthening with W, Mo, and Cu. Enhancing and C, Mn and B
We worked on solving the above problem by the basic idea of improving the weldability by controlling the addition amount of, and obtained the following knowledge.
【０００６】低Ｃｒフェライト鋳鋼においては、Ｓのマ
クロ偏析が最も生じ易く、その傾向は大鋳塊・弱脱酸材
程顕著になる。また、十分に脱酸を行っても、Ｓのマク
ロ偏析部にポロシティが集中し易いので、ポロシティに
よる材料劣化を抑えるためにも、Ｓのマクロ偏析を抑制
する必要がある。また、Ｓのミクロ偏析が生じると、つ
ぎの問題を引き起こす。（１）溶接時等での高温割れの
促進（２）Ｃｒ2 Ｏ3皮膜の不安定化による耐酸化性・
高温耐食性の低下（３）粒界強度の低下[0006] In low Cr ferritic cast steel, macro segregation of S is most likely to occur, and this tendency becomes more pronounced in large ingots and weakly deoxidized materials. In addition, even if deoxidation is sufficiently performed, porosity tends to concentrate on the macrosegregation portion of S. Therefore, it is necessary to suppress macrosegregation of S in order to suppress material deterioration due to porosity. In addition, the occurrence of S microsegregation causes the following problem. (1) Acceleration of high temperature cracking during welding, etc. (2) Oxidation resistance due to instability of Cr 2 O 3 coating
Decrease in high temperature corrosion resistance (3) Decrease in grain boundary strength
【０００７】したがって、低Ｃｒフェライト鋳鋼におい
て、Ｓの偏析を抑制する方法を検討した結果、以下の解
決法を見い出した。Ａｌで十分に脱酸を行なうと共に、
Ｓに対する親和力の強いＭｇを添加することにより、Ｓ
を安定化させることができるので、Ｓのマクロ偏析・ミ
クロ偏析を飛躍的に抑制することができる。その結果と
して、Ｓの偏析が原因となって生じた内部欠陥や溶接時
の高温割れを軽減させることができる。Therefore, as a result of studying a method for suppressing the segregation of S in a low Cr ferritic cast steel, the following solution was found. While deoxidizing sufficiently with Al,
By adding Mg having a strong affinity for S,
Can be stabilized, so that macro segregation and micro segregation of S can be drastically suppressed. As a result, internal defects caused by the segregation of S and high-temperature cracking during welding can be reduced.
【０００８】Ｓを安定化させる元素としては、Ｍｇの他
に、Ｃａや希土類がある。しかしながら、高温で使用さ
れる本発明の低Ｃｒフェライト鋳鋼においては、高温で
のスケールの安定性を確保することも重要である。Ｍｇ
はＣｒ2 Ｏ3 などのスケールを安定化させる作用もある
ので、Ｓを安定化させるためにはＭｇの添加が望まし
い。Ｍｇを添加した場合の効果は、Ｓ量・Ｏ量およびＡ
ｌ量とのバランスに支配され、つぎの式を満たす必要が
ある。Ｍｇ＞（２４／３２）Ｓ＋（２４／１６）〔Ｏ−
（３２／８１）Ａｌ〕すなわち、Ｍｇは、ＭｇＳとして
Ｓを安定化させる効果に加え、Ｍｇ単独であってもスケ
ールを安定化させる効果も有するのである。Elements for stabilizing S include Ca and rare earths in addition to Mg. However, in the low Cr ferritic cast steel of the present invention used at high temperatures, it is also important to ensure the stability of the scale at high temperatures. Mg
Also has the effect of stabilizing the scale of Cr 2 O 3 or the like, so that Mg should be added to stabilize S. The effects of adding Mg are as follows: S content, O content and A content.
It is governed by the balance with the amount of l, and the following equation must be satisfied. Mg> (24/32) S + (24/16) [O−
(32/81) Al] That is, Mg has the effect of stabilizing S as MgS and also has the effect of stabilizing the scale even if Mg alone is used.
【０００９】本発明者らは、上述のようにＳの偏析を抑
制する対策とその他の合金元素の適正化との相乗効果に
よって、本発明を完成するに至った。The present inventors have completed the present invention by the synergistic effect of the above-described countermeasure for suppressing the segregation of S and the optimization of other alloying elements.
【００１０】すなわち、本特発明は下記（１）〜（４）
の構成を有する低Ｃｒフェライト鋳鋼である。 （１） 重量％で、Ｃ：０．０３〜０．１２％、Ｓｉ：
０．０３〜０．７％、Ｍｎ：０．０２〜１％、Ｃｏ：
０．３％以下、Ｐ：０．０２５％以下、Ｓ：０．０１５
％以下、Ｃｒ：０．８〜３％、Ｎｉ：０．０１〜１％、
Ｖ：０．０１〜０．５％、Ｗ：０．１〜３％、Ｎｂ：
０．０１〜０．２％、Ａｌ：０．００１〜０．０５％、
Ｂ：０．０００１〜０．０２％、Ｎ：０．００１〜０．
０５％、Ｏ：０．０３％以下、Ｍｇ：０．０００５〜
０．０５％の範囲で、かつＭｇ＞（２４／３２）Ｓ＋
（２４／１６）〔Ｏ−（３２／８１）Ａｌ〕式を満足す
る量を含み残部は鉄および不可避的不純物からなる溶接
性に優れ、高温強度を飛躍的に向上させてなることを特
徴とする低Ｃｒフェライト鋳鋼。That is, the present invention provides the following (1) to (4)
It is a low Cr ferritic cast steel having the following configuration. (1) In weight%, C: 0.03 to 0.12%, Si:
0.03 to 0.7%, Mn: 0.02 to 1%, Co:
0.3% or less, P: 0.025% or less, S: 0.015
% Or less, Cr: 0.8 to 3%, Ni: 0.01 to 1%,
V: 0.01 to 0.5%, W: 0.1 to 3%, Nb:
0.01-0.2%, Al: 0.001-0.05%,
B: 0.0001-0.02%, N: 0.001-0.
05%, O: 0.03% or less, Mg: 0.0005 to
In the range of 0.05% and Mg> (24/32) S +
(24/16) [O- (32/81) Al] The balance is excellent in weldability including iron and unavoidable impurities, including the amount satisfying the formula, and the high-temperature strength is dramatically improved. Low-Cr ferritic cast steel.
【００１１】（２） 上記（１）記載の成分に加えて、
さらに重量％で０．０１〜０．２％のＣａ，Ｔｉ，Ｚ
ｒ，Ｙ，Ｌａ，Ｃｅ及びＴａよりなる群から選ばれた１
種または２種以上の元素を含有する溶接性に優れ、高温
強度を飛躍的に向上させてなることを特徴とする低Ｃｒ
フェライト鋳鋼。(2) In addition to the components described in the above (1),
Furthermore, 0.01% to 0.2% by weight of Ca, Ti, Z
1 selected from the group consisting of r, Y, La, Ce and Ta
Low Cr characterized by excellent weldability containing one or more kinds of elements and dramatically improved high-temperature strength
Ferrite cast steel.
【００１２】（３） 上記（１）または（２）記載の成
分に加えて、さらに重量％でＭｏ：０．０１〜３％を含
有する溶接性に優れ、高温強度を飛躍的に向上させてな
ることを特徴とする低Ｃｒフェライト鋳鋼。(3) In addition to the components described in the above (1) or (2), further contains Mo: 0.01 to 3% by weight, and has excellent weldability and dramatically improves high-temperature strength. A low Cr ferritic cast steel characterized in that:
【００１３】（４） 上記（１）、（２）および（３）
のいずれかに記載の成分に加えて、さらにＣｕを０．１
〜２．５％を含有する溶接性に優れ、高温強度を飛躍的
に向上させてなることを特徴とする低Ｃｒフェライト鋳
鋼。(4) The above (1), (2) and (3)
In addition to the components described in any of
A low Cr ferritic cast steel characterized by having excellent weldability containing up to 2.5% and having significantly improved high-temperature strength.
【００１４】[0014]
【発明の実施の形態】以下に各成分の作用とその含有量
の選定理由を説明する。説明中、％は重量％を示す。DESCRIPTION OF THE PREFERRED EMBODIMENTS The function of each component and the reason for selecting the content will be described below. In the description,% indicates% by weight.
【００１５】ＣはＣｒ，Ｆｅ，Ｗ，Ｖ，Ｎｂおよび必要
に応じて添加されるＭｏならびにＣｕと結合して炭化物
を形成し、高温強度に寄与するとともに、それ自身がオ
ーステナイト安定化元素として組織を安定化する。０．
０３％未満では炭化物析出が不十分で十分な高温強度が
得られず、また、０．１２％を超える場合は炭化物が過
剰析出して鋼が著しく硬化する。即ち、Ｃの適正含有量
は０．０３〜０．１２％である。C combines with Cr, Fe, W, V, Nb and optionally added Mo and Cu to form carbides and contributes to high-temperature strength, and itself forms a structure as an austenite stabilizing element. To stabilize. 0.
If it is less than 03%, carbide precipitation is insufficient and sufficient high-temperature strength cannot be obtained. If it exceeds 0.12%, carbide is excessively precipitated and the steel is hardened remarkably. That is, the appropriate content of C is 0.03 to 0.12%.
【００１６】Ｓｉは脱酸剤として働き、また耐水蒸気酸
化特性を高める元素であるが、０．７％を超えると靱性
が著しく低下しクリープ強度に対しても有害である。ま
た、０．０３％未満とすると鋳造時の湯流れ性が悪化す
ることから、Ｓｉの含有量は０．０３〜０．７％とす
る。[0016] Si acts as a deoxidizing agent and is an element that enhances the steam oxidation resistance. However, if it exceeds 0.7%, the toughness is remarkably reduced, and is harmful to the creep strength. If the content is less than 0.03%, the flowability of the molten metal at the time of casting deteriorates. Therefore, the content of Si is set to 0.03 to 0.7%.
【００１７】Ｍｎは脱硫および脱酸の効果があり、組織
の安定化に有効である。０．０２％未満では十分な効果
が得られず、１％を超えると鋼を硬化させるとともに焼
戻し脆化感受性を高める。また、Ｓが特に低い場合はＭ
ｎ添加量を少なくすることができる。よってＭｎの含有
量は０．０２〜１％とする。Mn has an effect of desulfurization and deoxidation, and is effective for stabilizing the structure. If it is less than 0.02%, a sufficient effect cannot be obtained, and if it exceeds 1%, the steel is hardened and the susceptibility to temper embrittlement is increased. When S is particularly low, M
The amount of n added can be reduced. Therefore, the content of Mn is set to 0.02 to 1%.
【００１８】Ｃｏは溶解の履歴によっては鋼中不純物と
して０．３％以下を含有する場合もあるが、０．３％以
下では特に有害な影響を与えないため、不可避な含有量
として０．３％以下とする。したがって、成分調整時に
はＣｏは積極的に添加する必要はない。Depending on the melting history, Co may contain 0.3% or less as an impurity in steel, but if it is 0.3% or less, it has no particularly harmful effect. % Or less. Therefore, it is not necessary to add Co positively at the time of component adjustment.
【００１９】Ｐ，Ｓはいずれも靱性に有害な元素で、Ｓ
が極微量であっても粒界やＣｒ2 Ｏ 3 スケール皮膜を不
安定にし、高温強度、靱性劣化の原因となるから、上記
の許容範囲内でもできるだけ少ないほうがよい。不可避
な含有量として、Ｐは０．０２５％以下、Ｓは０．０１
５％以下とした。P and S are both harmful to toughness.
Even if the amount is very small,TwoO ThreeScale coating
It is stable and causes deterioration of high temperature strength and toughness.
It is better to be as small as possible even within the allowable range. unavoidable
P is 0.025% or less and S is 0.01%
5% or less.
【００２０】Ｃｒは低合金鋼の耐酸化性、高温腐食性の
点から不可欠な元素であり、その含有量が０．８％未満
では十分な耐酸化性、高温腐食性が得られない。一方、
３％を超えて添加すると強度と靱性を損う。従って、Ｃ
ｒの含有量は０．８〜３％とする。Cr is an indispensable element in view of the oxidation resistance and high-temperature corrosion resistance of low alloy steel. If its content is less than 0.8%, sufficient oxidation resistance and high-temperature corrosion resistance cannot be obtained. on the other hand,
If it exceeds 3%, strength and toughness are impaired. Therefore, C
The content of r is set to 0.8 to 3%.
【００２１】Ｎｉはオーステナイト安定化元素であり、
かつ靱性改善に寄与するが、０．０．１％未満では十分
な効果が得られず、その含有量が１％を超えると高温ク
リープ強度を損う。また経済性を鑑みても大量添加は不
利である。従ってＮｉの含有量は０．００１〜１％とす
る。Ni is an austenite stabilizing element,
And it contributes to improvement of toughness, but if it is less than 0.1%, a sufficient effect cannot be obtained, and if its content exceeds 1%, high temperature creep strength is impaired. Also, in view of economy, large-scale addition is disadvantageous. Therefore, the content of Ni is set to 0.001 to 1%.
【００２２】ＶはＣ，Ｎと結合してＶ（Ｃ，Ｎ）等の微
細析出物を形成する。この析出物は高温での長時間クリ
ープ強度の向上に大きく寄与するが、０．０１％未満で
は十分な効果が得られず、０．５％を超える場合にはＶ
（Ｃ，Ｎ）の析出量が過剰となり、かえってクリープ強
度および靱性を損う。よって、Ｖの適正含有量は０．０
１〜０．５％である。V combines with C and N to form fine precipitates such as V (C, N). This precipitate greatly contributes to the improvement of the long-term creep strength at a high temperature. However, if the content is less than 0.01%, a sufficient effect cannot be obtained.
An excessive amount of (C, N) precipitates, which impairs creep strength and toughness. Therefore, the proper content of V is 0.0
1 to 0.5%.
【００２３】Ｗは固溶強化および微細炭化物析出強化元
素としてクリープ強度の向上に有効である。Ｍｏも同様
の効果があるが、Ｆｅ中での拡散速度の遅いＷの方がク
リープ強度に寄与する微細炭化物の高温安定性に優れて
いる。また、Ｍｏと複合添加された場合は、単独添加以
上に強度が向上し、特に高温クリープ強度が改善され
る。０．１％未満では効果がなく、３％を超えると鋼を
硬化させ靱性を損うため０．１〜３％の範囲とする。W is effective for improving the creep strength as a solid solution strengthening element and a fine carbide precipitation strengthening element. Mo has the same effect, but W having a lower diffusion rate in Fe is superior in high-temperature stability of fine carbides that contribute to creep strength. In addition, when Mo is added in combination with Mo, the strength is improved more than the addition of Mo alone, and particularly, the high temperature creep strength is improved. If it is less than 0.1%, there is no effect, and if it exceeds 3%, the steel is hardened and the toughness is impaired, so the content is made 0.1 to 3%.
【００２４】ＮｂはＶと同様Ｃ，Ｎと結合してＮｂ
（Ｃ，Ｎ）を形成しクリープ強度に寄与する。特に６０
０℃以下の比較的低温では著しい強度改善を示す。０．
０１％未満では上記の効果が得られず、また０．２％を
超える場合は鋼を著しく硬化させ靱性、溶接性を損う。
したがってＮｂ含有量は０．０１％〜０．２％が適当で
ある。Nb, like V, combines with C and N to form Nb
It forms (C, N) and contributes to creep strength. Especially 60
At a relatively low temperature of 0 ° C or lower, a remarkable strength improvement is exhibited. 0.
If it is less than 01%, the above effects cannot be obtained, and if it exceeds 0.2%, the steel is hardened significantly and the toughness and weldability are impaired.
Therefore, the Nb content is suitably 0.01% to 0.2%.
【００２５】Ａｌは脱酸素元素として必須であり、炭窒
化物を形成する。また、組織を微細化する効果もある。
含有量として０．００１％以下では効果がなく、０．０
５％を超える場合はクリープ強度と加工性を損うため、
Ａｌの含有量は０．００１〜０．０５％とする。Al is essential as a deoxidizing element and forms carbonitride. It also has the effect of making the structure finer.
When the content is 0.001% or less, there is no effect.
If it exceeds 5%, the creep strength and workability are impaired.
The content of Al is set to 0.001 to 0.05%.
【００２６】Ｂは極微量の添加により炭化物を分散、安
定化させる効果があり、長時間クリープ強度の改善に寄
与する。０．０００１％未満ではその効果が小さく、
０．０２％を超えると加工性を損うから、Ｂの添加はそ
の含有量を０．０００１〜０．０２％の範囲にするのが
よい。この範囲においてもＢの添加は焼入れ性向上にも
効果があるため、組織制御の観点から必要に応じて添加
量は調整する必要がある。B has an effect of dispersing and stabilizing carbides by adding a trace amount thereof, and contributes to improvement of long-time creep strength. If less than 0.0001%, the effect is small,
If the content exceeds 0.02%, the workability is impaired. Therefore, the content of B is preferably adjusted to the range of 0.0001 to 0.02%. Even in this range, the addition of B is effective in improving the hardenability, so that the addition amount needs to be adjusted as necessary from the viewpoint of controlling the structure.
【００２７】ＮはＶ，Ｎｂとの炭窒化物形成に必要で、
０．００１％未満ではその効果がない。しかしながらＮ
量が高くなると固溶状態のＮが増加し、また窒化物が粗
大化するためクリープ強度を損う。さらに、０．０５％
を超えると、鋳込み時にブローホールを形成する要因と
もなる。よってＮの含有量は、０．００１〜０．０５％
とする。N is necessary for carbonitride formation with V and Nb.
Less than 0.001% has no effect. However N
As the amount increases, N in the solid solution state increases, and the nitride becomes coarse, thereby impairing the creep strength. In addition, 0.05%
Exceeding the above may be a factor of forming blowholes during casting. Therefore, the content of N is 0.001 to 0.05%
And
【００２８】Ｏはパイプ、気泡など鋳造欠陥を増加さ
せ、さらに靱性、熱間加工性にも悪影響を及ぼすので、
０．０３％とする。好ましくは０．０２％以下である。O increases the number of casting defects such as pipes and bubbles, and also adversely affects toughness and hot workability.
0.03%. Preferably it is 0.02% or less.
【００２９】ＭｇはＳを安定化し、鋳造時のＳの偏析に
起因するポロシテイの抑制、溶接欠陥の抑制、粒界強化
に有効な元素である。また、Ｃｒ2 Ｏ3 皮膜、また後述
するＣｕ添加の場合にはＣｕ−Ｏ皮膜を安定化する重要
な元素である。しかしながら、その含有量が、０．００
０５％以下か、もしくはＭｇ＞（２４／３２）Ｓ＋（２
４／１６）〔Ｏ−（３２／８１）Ａｌ〕を満たさない場
合には所定の効果が得られない。また、０．０５％を超
えて含有させても効果は飽和する。したがって、Ｍｇの
含有量は０．０００５〜０．０５％で、かつＭｇ＞（２
４／３２）Ｓ＋（２４／１６）〔Ｏ−（３２／８１）Ａ
ｌ〕式を満足する範囲とする。ここで上式はＳおよびＯ
で固定されない単独で固溶するＭｇ量を確保することを
意味する。Mg is an element that stabilizes S, is effective in suppressing porosity caused by segregation of S during casting, suppressing welding defects, and strengthening grain boundaries. Further, it is an important element for stabilizing the Cr 2 O 3 film and, in the case of adding Cu described later, the Cu—O film. However, its content is 0.00
05% or less, or Mg> (24/32) S + (2
4/16) [O- (32/81) Al], the predetermined effect cannot be obtained. The effect is saturated even if the content exceeds 0.05%. Therefore, the content of Mg is 0.0005 to 0.05%, and Mg> (2
4/32) S + (24/16) [O- (32/81) A
l] A range satisfying the expression. Where the above equations are S and O
Means that the amount of Mg that is not fixed and is dissolved in a single solution is secured.
【００３０】Ｃａ，Ｔｉ，Ｚｒ，Ｙ，Ｌａ，Ｃｅ，Ｔａ
は不純物であるＰ，Ｏ，Ｓと結合し、それらの析出物
（介在物）の形態制御を目的として１種または２種以上
で微量添加される。それぞれを０．０１％以上添加する
ことによって、不純物であるＰ，Ｏ，Ｓを清浄化し、強
度と靱性を改善できる。特にクリープ強度に対しても有
効である。しかし、０．２％を超えると介在物が増加
し、かえって靱性を損うことからその添加量をそれぞれ
０．０１〜０．２％の範囲とした。Ca, Ti, Zr, Y, La, Ce, Ta
Are combined with impurities P, O, and S, and one or more of them are added in trace amounts for the purpose of controlling the morphology of their precipitates (inclusions). By adding 0.01% or more of each, P, O, and S, which are impurities, can be cleaned, and strength and toughness can be improved. It is particularly effective for creep strength. However, when the content exceeds 0.2%, inclusions increase, and on the contrary, the toughness is impaired. Therefore, the added amount is set in the range of 0.01 to 0.2%.
【００３１】ＭｏはＷと同様にクリープ強度の向上に有
効であるが、Ｗを多量添加する本発明鋼では必ずしも添
加する必要はない。しかし、Ｗと複合添加された場合は
強度向上の効果があり、かつ少量であれば靱性改善にも
有効である。Ｍｏの含有量が０．０１％未満では上記の
効果が得られず、３％を超えると高温で金属間化合物が
析出し、靱性が低下するだけでなく強度に対しても効果
がなくなる。従って、Ｍｏを添加する場合には含有量は
０．０１〜３％とする。Mo is effective in improving the creep strength similarly to W, but it is not always necessary to add Mo in the steel of the present invention to which a large amount of W is added. However, when added in combination with W, it has an effect of improving strength, and a small amount is effective for improving toughness. If the Mo content is less than 0.01%, the above effects cannot be obtained. If the Mo content exceeds 3%, the intermetallic compound is precipitated at a high temperature, and not only the toughness is reduced but also the effect on the strength is lost. Therefore, when Mo is added, the content is set to 0.01 to 3%.
【００３２】Ｃｕは固溶強化と析出効果により鋼の強度
を改善するとともに耐酸化性向上にも寄与する。また、
組織をマルテンサイトあるいはベイナイトとし、靱性の
改善にも有効である。ただし、過剰のＣｕの添加は著し
く鋼を硬化するため、鍛造あるいは圧廷などの加工を施
す必要がない本発明鋼では、Ｃｕを添加する場合には添
加量は最大２．５％とし下限は０．１％とする。Cu improves the strength of steel by the effect of solid solution strengthening and precipitation and also contributes to the improvement of oxidation resistance. Also,
The structure is martensite or bainite, which is effective for improving toughness. However, since the addition of excessive Cu hardens the steel significantly, the steel of the present invention, which does not need to be subjected to forging, pressing, or the like, has a maximum addition of 2.5% when Cu is added, and the lower limit is 0.1%.
【００３３】[0033]
【実施例】表１に示す化学成分の鋼を３０ｋｇ真空溶解
炉で溶解して、Ｙ型試験片の形状に鋳込みを行い、その
後徐冷した。Ａ鋼およびＢ鋼は既存の代表的な鋳鋼材で
あり、それぞれＪＩＳのＳＣＰＨ２１、ＳＣＰＨ３２に
相当する成分である。Ｃ鋼及びＤ鋼はボイラ等で使用さ
れる小径管用耐熱鋼の成分である。Ｅ鋼〜Ｍ鋼は合金成
分を本発明範囲外に変化させた比較鋼である。そして、
１〜２４鋼が本発明鋼である。EXAMPLE 30 kg of steel having the chemical composition shown in Table 1 was melted in a vacuum melting furnace, cast into a Y-shaped test piece, and then gradually cooled. Steels A and B are existing typical cast steel materials, and are components corresponding to JIS SCPH21 and SCPH32, respectively. C steel and D steel are components of heat resistant steel for small diameter pipes used in boilers and the like. Steels E to M are comparative steels in which alloy components are changed outside the range of the present invention. And
1 to 24 steels are the steels of the present invention.
【００３４】Ａ鋼〜Ｄ鋼は通常の熱処理として９５０℃
×２ｈ・ＡＣの焼きならし後、７３０℃×２ｈ・ＡＣの
焼き戻し、Ｅ鋼〜Ｍ鋼および本発明鋼１〜２４鋼は１０
５０℃×２ｈ・ＡＣの焼きならし後、７７０℃×１．５
ｈ・ＡＣの焼き戻しを行った。Steels A to D are heated at 950 ° C.
× 2h · AC normalizing, 730 ° C × 2h · AC tempering, E steel to M steel and invention steels 1 to 24 steel
After normalizing at 50 ° C x 2h AC, 770 ° C x 1.5
Tempering of h · AC was performed.
【００３５】鋳塊の厚さ１／４及び１／２の断面におい
て、ダイチェックを行い内部欠陥の発生状況を観察し
た。Ｍｇの含有量が本発明の範囲外である比較例Ｎにお
いては、鋳塊の厚さ１／４及び１／２のいずれの断面に
おいても欠陥が認められ、クリープ特性、溶接性のいず
れも不十分であった。一方、本発明の鋳鋼においては内
部欠陥は全く認められなかった。Die check was performed on cross sections of the ingot having thicknesses of 1/4 and 1/2 to observe the occurrence of internal defects. In Comparative Example N, in which the content of Mg was out of the range of the present invention, defects were recognized in both sections of the ingot thickness of 1/4 and 1/2, and neither creep characteristics nor weldability was found. Was enough. On the other hand, no internal defects were observed in the cast steel of the present invention.
【００３６】機械的性質を比較するため、比較鋼および
本発明鋼に対して、常温引張試験、シャルピー衝撃試
験、クリープ破断試験を実施した。また、溶接性につい
て評価するため、ｙ型溶接割れ試験を行った。常温引張
試験およびクリープ破断試験はＹ型試験片の底部より凝
固方向に対して垂直に直径６ｍｍ×標点間距離３０ｍｍ
の試験片を採取した。引張試験は室温にて、クリープ試
験は５００℃、５５０℃、６００℃、６５０℃において
最長１００００ｈ程度の長時間破断試験を行い６００℃
×１００００ｈクリープ破断強度を求めた。シャルピー
衝撃試験はＪＩＳＺ２２０２に準拠して、４号試験片に
て、０℃で各３回ずつ試験を行い、衝撃値の平均値を求
めた。また、ｙ型溶接割れ試験ではＪＩＳ Ｚ３１５８
に準拠して、板厚を２０ｍｍとし、予熱なし（２０℃）
で試験を行った。溶接性は樹断面割れ率により評価し
た。In order to compare the mechanical properties, the comparative steel and the steel of the present invention were subjected to a room temperature tensile test, a Charpy impact test, and a creep rupture test. In order to evaluate the weldability, a y-type weld crack test was performed. The room-temperature tensile test and the creep rupture test were 6 mm in diameter perpendicular to the solidification direction from the bottom of the Y-type test piece and the distance between gauge points was 30 mm.
Of test pieces were collected. Tensile test is performed at room temperature, and creep test is performed at 500 ° C, 550 ° C, 600 ° C, and 650 ° C for a long-term fracture test of up to about 10,000 hours at 600 ° C.
× 10000h The creep rupture strength was determined. The Charpy impact test was conducted three times at 0 ° C. on a No. 4 test piece in accordance with JISZ2202, and the average value of the impact values was determined. In addition, in the y-type welding crack test, JIS Z3158
According to, the plate thickness is set to 20 mm and there is no preheating (20 ° C)
Was tested. Weldability was evaluated based on the crack rate of the tree section.
【００３７】表２に試験結果を示す。本発明鋼は引張試
験において、引張強さが６００〜７００ＭＰａの範囲で
あり、伸びも２０％以上であった。高温強度を示す６０
０℃×１００００ｈクリープ破断強度は既存鋼を含む比
較鋼では最大でも８４ＭＰａであるのに対し、本発明鋼
では１３０ＭＰａ以上となり、高温での強度が１．５倍
以上と大幅に向上していることがわかる。その中でも、
Ｍｏを添加した４，５鋼は１鋼〜３鋼よりクリープ破断
強度が高く、さらにＣｕを添加した１１鋼ではさらにク
リープ破断強度が増している。１６鋼〜２４鋼にはＣ
ａ，Ｔｉ，Ｚｒ，Ｙ，Ｌａ，Ｃｅ，ＴａならびにＭｇを
１種または２種以上添加しており、不純部であるＰやＳ
が比較的多い場合においても、クリープ破断強度は低下
せず、高温強度に優れている。Table 2 shows the test results. In the tensile test, the steel of the present invention had a tensile strength in a range of 600 to 700 MPa and an elongation of 20% or more. High temperature strength 60
The creep rupture strength at 0 ° C x 10000h is at most 84MPa for comparative steels including existing steels, but is 130MPa or more for the steels of the present invention, and the strength at high temperatures is significantly improved to 1.5 times or more. I understand. Among them,
The steels 4 and 5 to which Mo was added had higher creep rupture strength than the steels 1 to 3, and the steel 11 to which Cu was added further increased the creep rupture strength. C for 16 to 24 steels
a, Ti, Zr, Y, La, Ce, Ta and Mg, one or more of which are added, and P or S
, The creep rupture strength does not decrease and the high temperature strength is excellent.
【００３８】比較鋼のなかでもっとも衝撃特性に優れた
ものにおいても、衝撃値は１２６Ｊ／ｃｍ2 以下である
のに対し、本発明鋼は１７６Ｊ／ｃｍ2 以上の衝撃値を
示しており、低温での靱性に富んでいるといえる。ｙ型
溶接割れ試験から、いずれの比較鋼においても、全面割
れまたは一部割れの発生がみられたのに対し、本発明鋼
は２０℃でも割れの発生がまったくみられないことか
ら、非常に優れた溶接性を有し、溶接時の予熱を省略で
きることがわかる。Even among the comparative steels having the highest impact characteristics, the impact value is 126 J / cm 2 or less, while the steel of the present invention shows an impact value of 176 J / cm 2 or more. It can be said that it is rich in toughness. From the y-type weld cracking test, any of the comparative steels was found to have cracks on the entire surface or partly cracked, whereas the steel of the present invention showed no cracking even at 20 ° C. It can be seen that it has excellent weldability and can omit preheating during welding.
【００３９】[0039]
【表１】 [Table 1]
【００４０】[0040]
【表２】 [Table 2]
【００４１】[0041]
【表３】 [Table 3]
【００４２】[0042]
【発明の効果】本発明は従来の低Ｃｒフェライト鋳鋼の
高温強度を大幅に改善し、優れた衝撃特性および溶接性
を兼ね備えた材料である。よって、従来、鍛鋼が使用さ
れていた箇所に対して、優れた特性を有する本発明鋼に
代替することが可能であり、より安価でかつ信頼性を増
すことができる。本発明鋼はボイラ、化学工業、原子力
などの産業分野で使用される耐熱耐圧部材として、さま
ざまな形状の鋳鋼品などに広く適用できるものである。The present invention is a material which significantly improves the high temperature strength of a conventional low Cr ferritic cast steel and has excellent impact properties and weldability. Therefore, it is possible to replace the place where a forged steel has been used in the past with the steel of the present invention having excellent characteristics, and it is possible to reduce the cost and increase the reliability. INDUSTRIAL APPLICABILITY The steel of the present invention can be widely applied to cast steel products of various shapes as heat and pressure resistant members used in industrial fields such as boilers, chemical industries, and nuclear power.
フロントページの続き (72)発明者 横山 知充 東京都千代田区丸の内二丁目５番１号 三 菱重工業株式会社内 (72)発明者 宮田 佳織 大阪府大阪市中央区北浜４丁目５番33号 住友金属工業株式会社内 (72)発明者 五十嵐 正晃 大阪府大阪市中央区北浜４丁目５番33号 住友金属工業株式会社内 (72)発明者 椹木 義淳 大阪府大阪市中央区北浜４丁目５番33号 住友金属工業株式会社内Continuing from the front page (72) Inventor Chimitsu Yokoyama 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Within Sanishi Heavy Industries, Ltd. (72) Inventor Kaori Miyata 4-33 Kitahama, Chuo-ku, Osaka City, Osaka Sumitomo Inside Metal Industry Co., Ltd. (72) Inventor Masaaki Igarashi 4-33, Kitahama, Chuo-ku, Osaka City, Osaka Prefecture Inside Sumitomo Metal Industries Co., Ltd. (72) Yoshijun Sawaragi 4-5-Kitahama, Chuo-ku, Osaka City, Osaka Prefecture No. 33 Sumitomo Metal Industries, Ltd.
Claims (4)
Ｓｉ：０．０３〜０．７％、Ｍｎ：０．０２〜１％、Ｃ
ｏ：０．３％以下、Ｐ：０．０２５％以下、Ｓ：０．０
１５％以下、Ｃｒ：０．８〜３％、Ｎｉ：０．０１〜１
％、Ｖ：０．０１〜０．５％、Ｗ：０．１〜３％、Ｎ
ｂ：０．０１〜０．２％、Ａｌ：０．００１〜０．０５
％、Ｂ：０．０００１〜０．０２％、Ｎ：０．００１〜
０．０５％、Ｏ：０．０３％以下、Ｍｇ：０．０００５
〜０．０５％の範囲で、かつＭｇ＞（２４／３２）Ｓ＋
（２４／１６）〔Ｏ−（３２／８１）Ａｌ〕式を満足す
る量を含み残部は鉄および不可避的不純物からなる溶接
性に優れ、高温強度を飛躍的に向上させてなることを特
徴とする低Ｃｒフェライト鋳鋼。C .: 0.03 to 0.12% by weight,
Si: 0.03 to 0.7%, Mn: 0.02 to 1%, C
o: 0.3% or less, P: 0.025% or less, S: 0.0
15% or less, Cr: 0.8-3%, Ni: 0.01-1
%, V: 0.01 to 0.5%, W: 0.1 to 3%, N
b: 0.01 to 0.2%, Al: 0.001 to 0.05
%, B: 0.0001 to 0.02%, N: 0.001 to
0.05%, O: 0.03% or less, Mg: 0.0005
~ 0.05% and Mg> (24/32) S +
(24/16) [O- (32/81) Al], the balance being excellent in weldability including iron and unavoidable impurities including the amount that satisfies the formula, and the high-temperature strength is dramatically improved. Low-Cr ferritic cast steel.
量％で０．０１〜０．２％のＣａ，Ｔｉ，Ｚｒ，Ｙ，Ｌ
ａ，Ｃｅ及びＴａよりなる群から選ばれた１種または２
種以上の元素を含有する溶接性に優れ、高温強度を飛躍
的に向上させてなることを特徴とする低Ｃｒフェライト
鋳鋼。2. The composition according to claim 1, further comprising 0.01 to 0.2% by weight of Ca, Ti, Zr, Y, L.
one or two selected from the group consisting of a, Ce and Ta
A low Cr ferritic cast steel characterized by excellent weldability containing at least one element and greatly improved high-temperature strength.
さらに重量％でＭｏ：０．０１〜３％を含有する溶接性
に優れ、高温強度を飛躍的に向上させてなることを特徴
とする低Ｃｒフェライト鋳鋼。3. In addition to the component according to claim 1 or 2,
Furthermore, a low Cr ferritic cast steel characterized by excellent weldability containing Mo: 0.01 to 3% by weight and having significantly improved high-temperature strength.
の成分に加えて、さらにＣｕを０．１〜２．５％を含有
する溶接性に優れ、高温強度を飛躍的に向上させてなる
ことを特徴とする低Ｃｒフェライト鋳鋼。4. In addition to the component according to any one of claims 1, 2 and 3, further comprising 0.1 to 2.5% of Cu, which is excellent in weldability and dramatically improves high-temperature strength. Low Cr ferritic cast steel characterized by the following.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26852996A JP3572152B2 (en) | 1996-10-09 | 1996-10-09 | Low Cr ferritic cast steel with excellent high temperature strength and weldability |
| DE1997608574 DE69708574T2 (en) | 1996-10-09 | 1997-08-22 | Use of a weldable ferritic cast steel with a low chromium content and very good heat resistance |
| EP19970306432 EP0835946B1 (en) | 1996-10-09 | 1997-08-22 | Use of a weldable low-chromium ferritic cast steel, having excellent high-temperature strength |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP26852996A JP3572152B2 (en) | 1996-10-09 | 1996-10-09 | Low Cr ferritic cast steel with excellent high temperature strength and weldability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH10121188A true JPH10121188A (en) | 1998-05-12 |
| JP3572152B2 JP3572152B2 (en) | 2004-09-29 |
Family
ID=17459790
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP26852996A Expired - Lifetime JP3572152B2 (en) | 1996-10-09 | 1996-10-09 | Low Cr ferritic cast steel with excellent high temperature strength and weldability |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0835946B1 (en) |
| JP (1) | JP3572152B2 (en) |
| DE (1) | DE69708574T2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6494970B1 (en) * | 2000-07-13 | 2002-12-17 | Kabushiki Kaisha Toshiba | Heat resistant steel casting and method of manufacturing the same |
| JP2008544083A (en) * | 2006-02-01 | 2008-12-04 | バラット ヘビー エレクトリカルズ リミテッド | Addition of niobium to Cr-Mo-1 / 4V cast steel for steam turbine casing |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3483493B2 (en) * | 1999-03-19 | 2004-01-06 | 日本鋳鍛鋼株式会社 | Cast steel for pressure vessel and method of manufacturing pressure vessel using the same |
| FR3014114B1 (en) * | 2013-12-04 | 2017-05-12 | C T I F - Centre Technique Des Ind De La Fond | MICRO-ALLIE STEEL |
| CN114480978A (en) * | 2022-01-11 | 2022-05-13 | 中国船舶重工集团公司第七二五研究所 | Non-quenched and tempered microalloy cast steel and heat treatment method thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02217438A (en) * | 1989-02-20 | 1990-08-30 | Sumitomo Metal Ind Ltd | Heat-resistant steel having high creep strength at high temperature |
| JPH04268040A (en) * | 1991-02-22 | 1992-09-24 | Sumitomo Metal Ind Ltd | Heat resisting low alloy steel excellent in creep strength and toughness |
| JPH05214492A (en) * | 1991-12-12 | 1993-08-24 | Nkk Corp | Fe-ni alloy excellent in sticking and seizure preventing property at the time of annealing and gas diffusing property and its production |
| JPH05345949A (en) * | 1992-03-12 | 1993-12-27 | Sumitomo Metal Ind Ltd | Heat resistant low cr ferritic steel excellent in toughness and creep strength |
| JPH08209293A (en) * | 1995-11-27 | 1996-08-13 | Hitachi Ltd | Steam turbine |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE977847C (en) * | 1965-02-07 | 1971-09-02 | Huettenwerk Oberhausen Ag | Use of steel as a material for armor plates or plates |
| JPH062927B2 (en) * | 1989-02-20 | 1994-01-12 | 住友金属工業株式会社 | High strength low alloy steel with excellent corrosion resistance and oxidation resistance |
| EP0411515B1 (en) * | 1989-07-31 | 1993-09-08 | Mitsubishi Jukogyo Kabushiki Kaisha | High strength heat-resistant low alloy steels |
| JP2659814B2 (en) * | 1989-08-30 | 1997-09-30 | 三菱重工業株式会社 | Manufacturing method of high strength low alloy heat resistant steel |
-
1996
- 1996-10-09 JP JP26852996A patent/JP3572152B2/en not_active Expired - Lifetime
-
1997
- 1997-08-22 DE DE1997608574 patent/DE69708574T2/en not_active Expired - Lifetime
- 1997-08-22 EP EP19970306432 patent/EP0835946B1/en not_active Expired - Lifetime
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02217438A (en) * | 1989-02-20 | 1990-08-30 | Sumitomo Metal Ind Ltd | Heat-resistant steel having high creep strength at high temperature |
| JPH04268040A (en) * | 1991-02-22 | 1992-09-24 | Sumitomo Metal Ind Ltd | Heat resisting low alloy steel excellent in creep strength and toughness |
| JPH05214492A (en) * | 1991-12-12 | 1993-08-24 | Nkk Corp | Fe-ni alloy excellent in sticking and seizure preventing property at the time of annealing and gas diffusing property and its production |
| JPH05345949A (en) * | 1992-03-12 | 1993-12-27 | Sumitomo Metal Ind Ltd | Heat resistant low cr ferritic steel excellent in toughness and creep strength |
| JPH08209293A (en) * | 1995-11-27 | 1996-08-13 | Hitachi Ltd | Steam turbine |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6494970B1 (en) * | 2000-07-13 | 2002-12-17 | Kabushiki Kaisha Toshiba | Heat resistant steel casting and method of manufacturing the same |
| JP2008544083A (en) * | 2006-02-01 | 2008-12-04 | バラット ヘビー エレクトリカルズ リミテッド | Addition of niobium to Cr-Mo-1 / 4V cast steel for steam turbine casing |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0835946B1 (en) | 2001-11-28 |
| JP3572152B2 (en) | 2004-09-29 |
| DE69708574T2 (en) | 2002-07-04 |
| EP0835946A1 (en) | 1998-04-15 |
| DE69708574D1 (en) | 2002-01-10 |
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