JP3451993B2 - Cr-containing steel for oil country tubular goods with excellent corrosion resistance to hydrogen sulfide and carbon dioxide - Google Patents
Cr-containing steel for oil country tubular goods with excellent corrosion resistance to hydrogen sulfide and carbon dioxideInfo
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- JP3451993B2 JP3451993B2 JP23264699A JP23264699A JP3451993B2 JP 3451993 B2 JP3451993 B2 JP 3451993B2 JP 23264699 A JP23264699 A JP 23264699A JP 23264699 A JP23264699 A JP 23264699A JP 3451993 B2 JP3451993 B2 JP 3451993B2
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- corrosion resistance
- carbon dioxide
- hydrogen sulfide
- country tubular
- tubular goods
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、油井あるいはガス
井 (以下、単に「油井」という。) に使用される油井管
用鋼に関し、硫化水素や炭酸ガスを含有する極めて腐食
環境の厳しい油井で使用されるのに適した耐硫化水素腐
食性および耐炭酸ガス腐食性能に優れたCr含有油井管用
鋼に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to oil well pipe steel used in oil wells or gas wells (hereinafter simply referred to as "oil wells"), and is used in oil wells containing hydrogen sulfide and carbon dioxide in a severely corrosive environment. TECHNICAL FIELD The present invention relates to a Cr-containing steel for oil country tubular goods having excellent hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance, which are suitable for being processed.
【０００２】[0002]
【従来の技術】近年、エネルギー資源の開発の拡大と、
入手容易な良質な石油資源の減少とに伴い、石油や天然
ガスを採取するための井戸環境がますます過酷なものに
なってきた。例えば、油田中の炭酸ガスの含有量が多い
深井戸のスゥイート油田が開発されている。このような
油井には、炭酸ガスや硫化水素が多く含まれているた
め、腐食等による油井管用鋼の脆化が大きな問題となっ
ている。2. Description of the Related Art In recent years, with the expansion of energy resource development,
With the reduction of readily available high-quality oil resources, well environments for extracting oil and natural gas have become increasingly harsh. For example, deep well sweet oil fields have been developed that have a high carbon dioxide content in the oil fields. Since such an oil well contains a large amount of carbon dioxide gas and hydrogen sulfide, the embrittlement of the steel for oil country tubular goods due to corrosion or the like has become a serious problem.
【０００３】従来は、一般炭素鋼とインヒビターとを併
用することが通常であったが、使用する油井の環境がこ
のように過酷になるにつれて、合金量を増加させた油井
管用鋼が用いられるようになってきた。Conventionally, it was usual to use general carbon steel and an inhibitor together, but as the environment of the oil well to be used becomes severe like this, steel for oil country tubular goods having an increased alloy amount is used. Has become.
【０００４】例えば、炭酸ガスを多量に含む油井では、
Cr添加が耐食性を著しく向上させることから、Crを13％
（以下、本明細書においては特にことわりがない限り、
「％」は「重量％」を意味するものとする。）含有した
SUS420マルテンサイト系ステンレス鋼が多く用いられて
きた。For example, in an oil well containing a large amount of carbon dioxide gas,
Addition of Cr significantly improves corrosion resistance, so 13% Cr
(Hereinafter, unless otherwise specified in this specification,
“%” Shall mean “% by weight”. ) Contained
SUS420 martensitic stainless steel has been widely used.
【０００５】ところが、Crを13％添加されたSUS420マル
テンサイト系ステンレス鋼は、耐硫化物応力腐食割れ性
が芳しくない。このため、炭酸ガスだけでなく硫化水素
をも同時に含むような環境下では、SUS420マルテンサイ
ト系ステンレス鋼は応力腐食割れ感受性が極めて高く、
その使用が制限されている。However, the SUS420 martensitic stainless steel containing 13% of Cr has poor sulfide stress corrosion cracking resistance. Therefore, in an environment containing not only carbon dioxide but also hydrogen sulfide, SUS420 martensitic stainless steel has extremely high sensitivity to stress corrosion cracking,
Its use is limited.
【０００６】このため、現状では、炭酸ガスと硫化水素
とをともに含む環境下では、さらに合金元素含有量を高
めた二相ステンレス鋼やスーパー二相ステンレス鋼を用
いざるを得ず、合金元素の添加量が増加することに起因
したコスト上昇を避けることができなかった。Therefore, under the present circumstances, in an environment containing both carbon dioxide gas and hydrogen sulfide, it is unavoidable to use a duplex stainless steel or a super duplex stainless steel having a higher alloy element content. The cost increase due to the increase of the addition amount cannot be avoided.
【０００７】そこで、例えば特開昭60−174859号公報、
特開平２−243739号公報、同２−243740号公報、同３−
120337号公報さらには同４−120249号公報等には、この
SUS420マルテンサイト系ステンレス鋼の耐硫化物応力腐
食割れ性を改良したマルテンサイト系ステンレス鋼が、
それぞれ提案されている。Therefore, for example, JP-A-60-174859,
JP-A-2-243739, JP-A-2-243740 and JP-A-3-
120337 gazette and further 4-120249 gazette, etc.
Martensitic stainless steel with improved sulfide stress corrosion cracking resistance of SUS420 martensitic stainless steel
Each has been proposed.
【０００８】[0008]
【発明が解決しようとする課題】しかし、これらの提案
にかかるマルテンサイト系ステンレス鋼は、炭酸ガスと
微量の硫化水素とをともに含有する環境を対象としてい
る。したがって、これらの提案にかかるマルテンサイト
系ステンレス鋼は、いずれも、硫化水素量が多い厳しい
環境下 (硫化水素分圧＝１気圧) においては耐硫化物応
力腐食割れ性が不十分である。However, the martensitic stainless steels according to these proposals are intended for an environment containing both carbon dioxide and a trace amount of hydrogen sulfide. Therefore, the martensitic stainless steels according to these proposals all have insufficient sulfide stress corrosion cracking resistance in a severe environment with a large amount of hydrogen sulfide (hydrogen sulfide partial pressure = 1 atm).
【０００９】一方、炭酸ガス環境下での鋼の腐食形態と
しては、全面腐食と局部腐食とがある。すなわち、油井
管を実際に使用する状況を考えると、たとえ炭酸ガス環
境下での油井管の耐全面腐食性が改善されても、油井管
本体の肉厚を貫通するほどの局部腐食が発生すると、こ
の油井管は使用できなくなる。したがって、油井管に全
面腐食だけが生じる場合は油井管の寿命予測を容易に行
うことができるが、局部腐食も生じる場合には油井管の
寿命予測は困難にある。このため、実用面からは、油井
管として使用される油井管用鋼には、炭酸ガス環境下で
局部腐食を生じないことも要求される。On the other hand, the corrosion forms of steel in a carbon dioxide environment include general corrosion and local corrosion. In other words, considering the situation in which the oil country tubular goods are actually used, even if the general corrosion resistance of the oil country tubular goods in a carbon dioxide gas environment is improved, local corrosion that would penetrate through the wall thickness of the oil country tubular body would occur. , This oil well pipe cannot be used. Therefore, when only the general corrosion of the oil country tubular goods occurs, the life of the oil country tubular goods can be easily predicted, but when the local corrosion also occurs, it is difficult to predict the life of the oil country tubular goods. Therefore, from the practical point of view, the steel for oil country tubular goods used as oil country tubular goods is also required not to cause local corrosion in a carbon dioxide gas environment.
【００１０】そこで、本発明者らは、先に特願平９−26
3561号により、Ｃ：0.08〜0.30％、Si：0.1 〜1.0 ％、
Mn：0.1 〜3.0 ％、Ｐ：0.03％以下、Ｓ：0.01％以下、
Cr：1.0 〜9.0 ％、Al：0.01〜0.10％、残部Feおよび不
可避的不純物からなる鋼組成を有し、焼入れまたは焼な
まし後の組織がマルテンサイト率95％以上で、更に、焼
戻し後、552MPa以上の耐力を有することを特徴とする焼
入れまたは焼なまし後焼戻した耐湿潤炭酸ガス腐食およ
び耐海水腐食性能に優れた油井管用鋼を、提案した。Therefore, the present inventors have previously proposed Japanese Patent Application No. 9-26.
According to No. 3561, C: 0.08 to 0.30%, Si: 0.1 to 1.0%,
Mn: 0.1-3.0%, P: 0.03% or less, S: 0.01% or less,
Cr: 1.0 to 9.0%, Al: 0.01 to 0.10%, with a steel composition consisting of the balance Fe and unavoidable impurities, the structure after quenching or annealing has a martensite ratio of 95% or more, and further after tempering, We have proposed a steel for oil country tubular goods which has a proof stress of 552 MPa or more and which is excellent in wet carbon dioxide corrosion resistance and seawater corrosion resistance after quenching or annealing and tempering.
【００１１】この提案によれば、耐炭酸ガス環境下での
局部腐食性能および耐海水腐食性能に優れた552MPa以上
の耐力を有する焼入れまたは焼なまし後焼戻した継目無
油井管が、提供される。According to this proposal, there is provided a seamless oil well tube which is excellent in local corrosion performance and seawater corrosion resistance in a carbon dioxide environment and has a proof stress of 552 MPa or more, which has been quenched or annealed and then tempered. .
【００１２】しかしながら、前述したように、井戸環境
はますます過酷なものになってきており、特願平９−26
3561号により提案された油井管用鋼が有する局部腐食性
能をより一層引き上げることが、望まれる。However, as described above, the well environment is becoming more and more severe, and Japanese Patent Application No. 9-26
It is desired to further improve the local corrosion performance of the steel for oil country tubular goods proposed by No. 3561.
【００１３】ここに、本発明の目的は、硫化水素や炭酸
ガスを含有する極めて腐食環境の厳しい油井で使用され
るのに適した耐硫化水素腐食性および耐炭酸ガス腐食性
能に優れたCr含有油井管用鋼を提供すること、具体的に
は、特願平９−263561号により提案された油井管用鋼が
有する局部腐食性能をより一層引き上げること、さらに
具体的には、耐力を552MPa以上(API規格の80ksi グレー
ド以上の耐力) という高強度に保って、炭酸ガスと硫化
水素との耐食性に優れた、焼入れまたは焼なまし後に焼
戻された油井管用鋼を提供することである。Here, the object of the present invention is to contain Cr containing hydrogen sulfide and carbon dioxide which are excellent in hydrogen sulfide corrosion resistance and carbon dioxide corrosion resistance and which are suitable for use in an oil well containing a severely corrosive environment. Providing steel for oil country tubular goods, more specifically, to further enhance the local corrosion performance of the steel for oil country tubular goods proposed by Japanese Patent Application No. 9-263561, and more specifically, yield strength of 552 MPa or more (API It is intended to provide a steel for oil country tubular goods that has been tempered after quenching or annealing and that has a high strength (proof strength of 80 ksi grade or higher of the standard) and has excellent corrosion resistance to carbon dioxide and hydrogen sulfide.
【００１４】[0014]
【課題を解決するための手段】前述したように、油井管
用鋼でCrの添加量を増加すれば耐炭酸ガス腐食性能は向
上するものの、耐硫化水素腐食性能が不十分なものとな
る。[Means for Solving the Problems] As described above, when the amount of Cr added in the steel for oil country tubular goods is increased, the carbon dioxide gas corrosion resistance is improved, but the hydrogen sulfide corrosion resistance is insufficient.
【００１５】そこで、本発明者らは、さらに検討を重ね
た結果、特願平９−263561号により提案された油井管用
鋼に、さらにNiと微量のＢを添加すること、特願平９−
263561号により開示された鋼組成をさらに調整し、か
つ、焼入れまま、または焼なましままの組織でマルテン
サイト率95％以上となるようにすることにより、特願平
９−263561号により提案された油井管用鋼の耐硫化水素
腐食性能を改善できること、すなわち、Cr含有鋼につい
ては、マルテンサイト単相の均一な組織にして炭酸ガス
環境下での耐局部腐食性能を確保できるとともに微量の
Ｂを添加して耐硫化水素腐食性能の低下を防止できるこ
とを知見して、本発明を完成した。Therefore, as a result of further studies, the present inventors further added Ni and a trace amount of B to the steel for oil country tubular goods proposed by Japanese Patent Application No. 9-263561.
Proposed by Japanese Patent Application No. 9-263561 by further adjusting the steel composition disclosed by No. 263561 and making the martensite ratio of 95% or more in the as-quenched or as-annealed structure. It is possible to improve the hydrogen sulfide corrosion resistance of steel for oil country tubular goods, that is, for Cr-containing steel, a martensite single-phase uniform structure can be formed to ensure local corrosion resistance in a carbon dioxide gas environment and trace amount of B The present invention has been completed by discovering that addition of hydrogen can prevent deterioration of hydrogen sulfide corrosion resistance.
【００１６】本発明は、Ｃ：0.08〜0.30％、Si：0.1 〜
1.0 ％、Mn：0.1 〜3.0 ％、Ｐ：0.03％以下、Ｓ：0.01
％以下、Cr：1.0 〜9.0 ％、Al：0.01〜0.10％、Ni：0.
01〜0.50％、Ｂ：0.0001〜0.0020％、残部Feおよび不可
避的不純物からなる鋼組成を有し、マルテンサイト率が
95％以上であり、552MPa以上の耐力を有することを特徴
とする耐硫化水素腐食性および耐炭酸ガス腐食性能に優
れたCr含有油井管用鋼である。In the present invention, C: 0.08 to 0.30%, Si: 0.1 to
1.0%, Mn: 0.1-3.0%, P: 0.03% or less, S: 0.01
% Or less, Cr: 1.0 to 9.0%, Al: 0.01 to 0.10%, Ni: 0.
01 to 0.50%, B: 0.0001 to 0.0020%, the steel composition consisting of balance Fe and unavoidable impurities, and the martensite ratio
A Cr-containing steel for oil country tubular goods that is excellent in hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance, characterized by having a yield strength of 552 MPa or more and 95% or more.
【００１７】具体的には、本発明は、Ｃ：0.08〜0.30
％、Si：0.1 〜1.0 ％、Mn：0.1 〜3.0 ％、Ｐ：0.03％
以下、Ｓ：0.01％以下、Cr：1.0 〜9.0 ％、Al：0.01〜
0.10％、Ni：0.01〜0.50％、Ｂ：0.0001〜0.0020％、残
部Feおよび不可避的不純物からなる鋼組成を有し、熱間
成形後の急冷または徐冷後のマルテンサイト率が95％以
上であって、さらにAc1 点以下の温度域での焼戻し後の
耐力が552MPa以上であることを特徴とする耐硫化水素腐
食性および耐炭酸ガス腐食性能に優れたCr含有油井管用
鋼である。Specifically, the present invention provides C: 0.08 to 0.30.
%, Si: 0.1 to 1.0%, Mn: 0.1 to 3.0%, P: 0.03%
Below, S: 0.01% or less, Cr: 1.0 to 9.0%, Al: 0.01 to
0.10%, Ni: 0.01 to 0.50%, B: 0.0001 to 0.0020%, with a steel composition consisting of the balance Fe and unavoidable impurities, and a martensite ratio of 95% or more after rapid cooling after hot forming or slow cooling. In addition, the Cr-containing steel for oil country tubular goods excellent in hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance is characterized in that the yield strength after tempering in the temperature range of Ac 1 point or less is 552 MPa or more.
【００１８】この本発明にかかる耐硫化水素腐食性およ
び耐炭酸ガス腐食性能に優れたCr含有油井管用鋼では、
(i) さらにMo：0.05〜0.3 ％を含有すること、および／
または、(ii)さらに、Ca、Mg、LaおよびCeからなる群か
ら選ばれた１種または２種以上を0.001 〜0.05％含有す
ることが、それぞれ望ましい。The Cr-containing steel for oil country tubular goods excellent in hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance according to the present invention comprises:
(i) It further contains Mo: 0.05 to 0.3%, and /
Alternatively, (ii) it is desirable that each further contain 0.001 to 0.05% of one or more selected from the group consisting of Ca, Mg, La and Ce.
【００１９】[0019]
【発明の実施の形態】以下、本発明の実施の形態を詳細
に説明する。まず、本発明にかかるCr含有油井管用鋼に
おいて、組成を限定する理由を説明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. First, the reason for limiting the composition of the Cr-containing steel for oil country tubular goods according to the present invention will be described.
【００２０】Ｃ：0.08〜0.30％
Ｃは、焼入れ性を高め、強度を向上させるために必要な
元素である。Ｃ含有量が0.08％未満では焼入れ性が不足
して高強度が得られない。一方、Ｃ含有量が0.30％を超
えると焼き割れが起こり易くなり、熱間加工が困難にな
る。そこで、本発明では、Ｃ含有量は0.08％以上0.30％
以下と限定する。同様の観点から、Ｃ含有量の上限は0.
25％であることが望ましく、下限は0.10％であることが
望ましい。 C: 0.08 to 0.30% C is an element necessary to enhance hardenability and strength. If the C content is less than 0.08%, the hardenability is insufficient and high strength cannot be obtained. On the other hand, if the C content exceeds 0.30%, quench cracking tends to occur, making hot working difficult. Therefore, in the present invention, the C content is 0.08% or more and 0.30% or more.
Limited to: From the same viewpoint, the upper limit of C content is 0.
It is preferably 25%, and the lower limit is preferably 0.10%.
【００２１】Si：0.1 〜1.0 ％
Siは、0.1 ％以上存在することにより脱酸成分として有
効な成分であるが、Si含有量が1.0 ％を超えると熱間加
工性および靱性にいずれも悪影響を及ぼす。そこで、本
発明では、Si含有量は0.1 ％以上1.0 ％以下と限定す
る。同様の観点からSi含有量の上限は、0.60％が望まし
い。 Si: 0.1 to 1.0% Si is an effective component as a deoxidizing component due to the presence of 0.1% or more, but if the Si content exceeds 1.0%, both hot workability and toughness are adversely affected. Exert. Therefore, in the present invention, the Si content is limited to 0.1% or more and 1.0% or less. From the same viewpoint, the upper limit of the Si content is preferably 0.60%.
【００２２】Mn：0.1 〜3.0 ％
Mnは、強度および靱性の改善を図るために0.1 ％以上含
有することが有効であるが、Mn含有量が3.0 ％を超える
と耐炭酸ガス腐食性能が低下する。そこで、本発明で
は、Mn含有量は0.1 ％以上3.0 ％以下と限定する。同様
の観点から、Mn含有量の下限は0.30％であることが望ま
しく、上限は2.6 ％であることが望ましい。 Mn: 0.1-3.0% Mn is effective to be contained in an amount of 0.1% or more in order to improve the strength and toughness, but when the Mn content exceeds 3.0%, the carbon dioxide corrosion resistance is deteriorated. . Therefore, in the present invention, the Mn content is limited to 0.1% or more and 3.0% or less. From the same viewpoint, the lower limit of the Mn content is desirably 0.30%, and the upper limit is desirably 2.6%.
【００２３】Ｐ：0.03％以下
Ｐは、不純物として鋼中に不可避的に存在するが、Ｐ含
有量が0.03％を超えると、粒界に偏析し、靱性および耐
硫化水素腐食性能を低下させる。そこで、本発明では、
Ｐ含有量は0.03％以下と限定する。 P: 0.03% or less P is inevitably present in the steel as an impurity, but if the P content exceeds 0.03%, it segregates at the grain boundaries and reduces toughness and hydrogen sulfide corrosion resistance. Therefore, in the present invention,
The P content is limited to 0.03% or less.
【００２４】Ｓ：0.01％以下
Ｓは、鋼中にあってはMnＳを生成して、靱性を劣化させ
る。そこで、本発明では、Ｓ含有量は0.01％以下と限定
する。 S: 0.01% or less S forms MnS in steel and deteriorates toughness. Therefore, in the present invention, the S content is limited to 0.01% or less.
【００２５】Cr：1.0 〜9.0 ％
Crは、焼入れ性を確保し、強度を向上させるとともに耐
炭酸ガス腐食性を向上させる成分である。Cr含有量が1.
0 ％未満ではかかる効果が認められず、一方Cr含有量が
9.0 ％を超えると耐硫化水素性能および靱性がともに低
下する。そこで、本発明では、Cr含有量は1.0 ％以上9.
0 ％以下と限定する。同様の観点から、Cr含有量の下限
は2.0 ％、上限は7.0 ％が望ましい。 Cr: 1.0 to 9.0% Cr is a component that secures hardenability, improves strength, and improves carbon dioxide corrosion resistance. Cr content is 1.
If it is less than 0%, such an effect is not observed, while the Cr content is
If it exceeds 9.0%, both hydrogen sulfide resistance and toughness are deteriorated. Therefore, in the present invention, the Cr content is 1.0% or more 9.
Limited to 0% or less. From the same viewpoint, it is desirable that the lower limit of Cr content be 2.0% and the upper limit thereof be 7.0%.
【００２６】Al：0.01〜0.10％
Alは、鋼の脱酸剤として必要な元素であるが、Al含有量
が0.01％未満では所望の脱酸効果が得られない。一方、
Al含有量が0.10％を超えると、非金属介在物が増加して
靱性および耐食性がともに劣化する。そこで、本発明で
は、Al含有量は0.01％以上0.10％以下と限定する。 Al: 0.01 to 0.10% Al is an element necessary as a deoxidizing agent for steel, but if the Al content is less than 0.01%, the desired deoxidizing effect cannot be obtained. on the other hand,
If the Al content exceeds 0.10%, the amount of nonmetallic inclusions increases and both the toughness and corrosion resistance deteriorate. Therefore, in the present invention, the Al content is limited to 0.01% or more and 0.10% or less.
【００２７】Ni：0.01〜0.50％
Niは、靱性を改善するために0.01％以上含有することが
有効である。しかし、Ni含有量が0.50％を超えると、耐
硫化水素腐食性能を低下させる。そこで、本発明では、
Ni含有量は0.01％以上0.50％以下と限定する。同様の観
点からNi含有量の上限は、0.20％であることが望まし
い。 Ni: 0.01 to 0.50% Ni is effectively contained in an amount of 0.01% or more in order to improve toughness. However, when the Ni content exceeds 0.50%, the hydrogen sulfide corrosion resistance performance deteriorates. Therefore, in the present invention,
The Ni content is limited to 0.01% or more and 0.50% or less. From the same viewpoint, the upper limit of the Ni content is preferably 0.20%.
【００２８】Ｂ：0.0001〜0.0020％
Ｂは、本発明にかかるCr含有油井管用鋼の耐硫化水素腐
食性能を向上させるのに有効な元素であり、Ｂ含有量が
0.0001％未満では十分な耐硫化水素腐食性能が得られな
い。しかし、Ｂ含有量が0.0020％を超えると、かえって
粒界を脆化し、耐硫化水素腐食性能および靱性をともに
低下させる。そこで、本発明では、Ｂ含有量は0.0001％
以上0.0020％以下と限定する。同様の観点から、Ｂ含有
量の上限は0.0015％以下であることが望ましい。 B: 0.0001 to 0.0020% B is an element effective for improving the hydrogen sulfide corrosion resistance of the Cr-containing steel for oil country tubular goods according to the present invention, and the B content is
If it is less than 0.0001%, sufficient hydrogen sulfide corrosion resistance cannot be obtained. However, if the B content exceeds 0.0020%, the grain boundaries are rather embrittled, and both hydrogen sulfide corrosion resistance and toughness are reduced. Therefore, in the present invention, the B content is 0.0001%.
It is limited to 0.0020% or less. From the same viewpoint, the upper limit of the B content is preferably 0.0015% or less.
【００２９】本発明にかかるCr含有油井管用鋼の上記以
外の成分は、Feおよび不可避的不純物であるが、さら
に、任意添加元素として、Mo、またはCa、Mg、Laおよび
Ceの１種以上を含有してもよい。そこで、次に、これら
任意添加元素についても説明する。Components other than the above components of the Cr-containing steel for oil country tubular goods according to the present invention are Fe and unavoidable impurities. Further, as optional additional elements, Mo, Ca, Mg, La and
You may contain 1 or more types of Ce. Therefore, next, these optional additional elements will be described.
【００３０】Mo：0.05〜0.3 ％
Moは、Crの共存下で炭酸ガス環境での局部腐食を向上す
るのに有効な元素であり、必要に応じて添加すればよ
い。しかし、Mo含有量が0.05％未満では十分な耐局部腐
食性が得られず、一方Mo含有量が0.3 ％超であると耐局
部腐食性を著しく向上させることが難しくなる。そこ
で、本発明において耐局部腐食性を充分に確保したい場
合には、Moを0.05％以上0.3 ％以下添加することが望ま
しい。 Mo: 0.05 to 0.3% Mo is an element effective in improving local corrosion in a carbon dioxide environment in the presence of Cr, and may be added if necessary. However, if the Mo content is less than 0.05%, sufficient local corrosion resistance cannot be obtained, while if the Mo content exceeds 0.3%, it becomes difficult to significantly improve the local corrosion resistance. Therefore, in the present invention, when it is desired to secure sufficient local corrosion resistance, it is desirable to add Mo in an amount of 0.05% or more and 0.3% or less.
【００３１】Ca、Mg、LaおよびCeの１種以上：合計で0.
001 〜0.05％
Ca、Mg、LaおよびCeは、いずれも、鋼の熱間加工性を向
上させる。そこで、本発明において鋼の熱間加工性を向
上させたい場合には、これらのうちの１種を単独で、ま
たは２種以上を複合して、添加することが望ましい。こ
れらの元素の含有量が、総量で0.001 ％未満では熱間加
工性が改善されず、一方0.05％を超えると粗大な酸化物
が生成し、かえって耐食性が低下する。そこで、Ca、M
g、LaおよびCeの１種または２種以上を添加する場合に
は、その含有量は総量で、0.001 ％以上0.05％以下であ
ることが望ましい。 One or more of Ca, Mg, La and Ce: 0 in total.
001-0.05% Ca, Mg, La and Ce all improve the hot workability of steel. Therefore, in order to improve the hot workability of steel in the present invention, it is desirable to add one of these alone or in combination of two or more. If the total content of these elements is less than 0.001%, the hot workability is not improved, while if it exceeds 0.05%, a coarse oxide is formed and the corrosion resistance is rather deteriorated. So Ca, M
When one or more of g, La and Ce are added, the total content is preferably 0.001% or more and 0.05% or less.
【００３２】本実施形態では、かかる鋼組成を有する鋼
材に熱間加工を行うことにより、所望の形状の素管に加
工する。なお、本発明における熱間加工は特に制限され
ないが、例えばマンネスマン・マンドレルミル法 (マン
ネスマン製管法) のような工程を経て行う製管法が、例
示される。In the present embodiment, a steel material having such a steel composition is hot-worked to be processed into a raw pipe having a desired shape. The hot working in the present invention is not particularly limited, but a pipe manufacturing method performed through steps such as the Mannesmann-mandrel mill method (Mannesmann pipe manufacturing method) is exemplified.
【００３３】さらに、本実施形態によれば、焼入れの急
冷後、またはその後の焼なましの徐冷後の組織がマルテ
ンサイト率95％以上となるようにするが、これは焼戻し
後、炭酸ガス環境下での耐局部腐食性能と所定の耐力を
確保するためであり、好ましくは、マルテンサイト率は
98％以上である。ここに、「マルテンサイト率」とは、
焼入れ後または焼なまし後のマルテンサイト組織率の割
合 (面積％) で示す。Further, according to the present embodiment, the structure after the quenching for quenching or for the subsequent annealing for slow cooling is made to have a martensite ratio of 95% or more. This is to ensure local corrosion resistance and predetermined yield strength under the environment, and preferably the martensite ratio is
98% or more. Here, "martensite ratio" means
The ratio (area%) of the martensite structure ratio after quenching or annealing is shown.
【００３４】なお、焼入れまたは焼なまし、焼戻し条件
は慣用のそれらであってもよく、本発明においては特に
制限されない。例示すれば、900 〜1100℃に加熱して水
焼入れまたは空冷し、次いで450 〜700 ℃に加熱して焼
戻しを行えばよい。The quenching, annealing, and tempering conditions may be those conventionally used, and are not particularly limited in the present invention. For example, it may be heated to 900 to 1100 ° C and water-quenched or air-cooled, and then heated to 450 to 700 ° C for tempering.
【００３５】このようにして、Ｃ：0.08〜0.30％、Si：
0.1 〜1.0 ％、Mn：0.1 〜3.0 ％、Ｐ：0.03％以下、
Ｓ：0.01％以下、Cr：1.0 〜9.0 ％、Al：0.01〜0.10
％、Ni：0.01〜0.50％、Ｂ：0.0001〜0.0020％、必要に
応じて、Mo：0.05〜0.3 ％、および／または、Ca、Mg、
LaおよびCeの１種以上：合計で0.001 〜0.05％、残部Fe
および不可避的不純物からなる鋼組成を有し、マルテン
サイト率が95％以上であり、552 MPa 以上の耐力を有す
る耐硫化水素腐食性および耐炭酸ガス腐食性能に優れた
Cr含有油井管用鋼が提供される。このCr含有油井管用鋼
は、耐硫化水素腐食性および耐炭酸ガス腐食性能がいず
れも優れるため、硫化水素や炭酸ガスを含有する極めて
腐食環境の厳しい油井において、特に好適に使用され
る。次に、実施例によって本発明の作用効果をさらに具
体的に説明する。Thus, C: 0.08 to 0.30%, Si:
0.1 to 1.0%, Mn: 0.1 to 3.0%, P: 0.03% or less,
S: 0.01% or less, Cr: 1.0 to 9.0%, Al: 0.01 to 0.10.
%, Ni: 0.01 to 0.50%, B: 0.0001 to 0.0020%, Mo: 0.05 to 0.3%, and / or Ca, Mg, if necessary.
One or more of La and Ce: 0.001 to 0.05% in total, balance Fe
And a steel composition consisting of unavoidable impurities, a martensite ratio of 95% or more, a proof stress of 552 MPa or more, and excellent hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance.
A Cr-containing steel for oil country tubular goods is provided. Since this Cr-containing steel for oil country tubular goods has both excellent hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance, it is particularly preferably used in oil wells containing hydrogen sulfide and carbon dioxide gas in an extremely severe corrosive environment. Next, the working effects of the present invention will be described more specifically by way of examples.
【００３６】[0036]
【実施例】表１に示される成分組成を有する溶湯を通常
の電気炉、並びに脱硫の目的でAr−酸素脱炭炉(AOD炉)
を使用して溶製した後、直径が550 mmのインゴットに鋳
造し、次いでこのインゴットに1200℃で熱間鍛造を行っ
て、直径が150 mmのビレットを成形した。EXAMPLE A molten metal having the composition shown in Table 1 was used for an ordinary electric furnace, and an Ar-oxygen decarburizing furnace (AOD furnace) for the purpose of desulfurization.
After being melted using, the ingot was cast into an ingot having a diameter of 550 mm, and this ingot was hot forged at 1200 ° C. to form a billet having a diameter of 150 mm.
【００３７】そして、引き続いてこのビレットを、マン
ネスマン製管法により直径が168 mmであって肉厚が12mm
の継目無管とした。そして、実際、850 〜1100℃加熱、
焼入れまたはその後の焼なまし時の冷却速度を0.5 〜50
℃/secにし、マルテンサイト率を78〜99％に変化させた
後、Ac1 点以下の500 〜690 ℃の温度域で焼戻しを行
い、552MPa(80ksi) 以上の耐力を有する鋼管を製作し
た。Then, this billet was subsequently processed by the Mannesmann tube-making method to have a diameter of 168 mm and a wall thickness of 12 mm.
No seamless pipe. And, in fact, 850 ~ 1100 ℃ heating,
Cooling rate during quenching or subsequent annealing 0.5 to 50
° C. / to sec, after changing the martensite ratio in the 78 to 99%, subjected to tempering at a temperature range of 500 690 ° C. or less 1 point Ac, was fabricated steel pipe having a 552 MPa (80 ksi) or more strength.
【００３８】そして、以下に示す各種試験の試験片に加
工して、引張試験、硬度測定、シャルピー試験とカソー
ド防食下での割れの試験を行った。溶接方法はASTM1Gに
従って行った。Then, the test pieces of various tests shown below were processed and subjected to a tensile test, a hardness measurement, a Charpy test and a crack test under cathodic protection. The welding method was according to ASTM 1G.
【００３９】(A) 引張試験
試験温度：常温
試験片：直径4.0 mm、平行部長さ20mm
(B) 硬度測定
焼入れ焼戻しまたは焼なまし焼戻し後、管長手方向に垂
直の断面を切り出し、HRC 硬度を測定した。(A) Tensile test test temperature: normal temperature test piece: diameter 4.0 mm, parallel part length 20 mm (B) Hardness measurement After quenching or tempering or annealing and tempering, a section perpendicular to the longitudinal direction of the pipe is cut out to determine the HRC hardness. It was measured.
【００４０】(C) マルテンサイト率
焼入れまま、または焼なましままの管長手方向に垂直の
断面を切り出し、100倍のミクロ組織を10視野観察し
て、それらの平均値をマルテンサイト率とした。(C) Martensite Ratio A section of the as-quenched or as-annealed section perpendicular to the longitudinal direction of the tube was cut out, and a 100-fold microstructure was observed in 10 fields of view, and the average value thereof was taken as the martensite rate. .
【００４１】(D) 炭酸ガス環境下での耐局部腐食試験
供試管から幅22mm、厚さ３mm、長さ76mmの試験片を切り
出し、600 番エメリー紙にて研磨した後、脱脂および乾
燥したものを試験片として用いた。この試験片に３bar.
で炭酸ガスを飽和させた５％NaCl水溶液を、流速2.5m/
s、液温60℃で720 時間流した。その後、目視により試
験片の局部腐食発生の有無を観察した。(D) Local Corrosion Resistance Test in Carbon Dioxide Environment A test piece with a width of 22 mm, a thickness of 3 mm and a length of 76 mm was cut out from a test tube, polished with No. 600 emery paper, degreased and dried. Was used as a test piece. 3 bar on this test piece.
5% NaCl aqueous solution saturated with carbon dioxide at a flow rate of 2.5 m /
s, the liquid temperature was 60 ° C, and the mixture was run for 720 hours. Then, the presence or absence of local corrosion of the test piece was visually observed.
【００４２】(E) 耐硫化水素腐食試験
NACE TM0177-96 Method A に準拠した定荷重試験を行
い、試験期間中に試験片が破断するか否かを調べた。
試験液：NACE B液
試験ガス：１bar.H2S
試験荷重：100 ％実YS
試験時間：720 時間
これらの試験結果を、表２にまとめて示す。なお、表２
では、炭酸ガス環境下で局部腐食が生じなかったものを
“○”で示し、生じたものを“×”で示した。また、表
２では、硫化水素腐食試験で試験片が破断しなかったも
のを“○”で示し、破断したものを“×”で示した。(E) Hydrogen Sulfide Corrosion Resistance Test A constant load test based on NACE TM0177-96 Method A was conducted to examine whether or not the test piece was broken during the test period. Test solution: NACE solution B Test gas: 1 bar.H 2 S Test load: 100% Actual YS test time: 720 hours These test results are summarized in Table 2. Table 2
In the table, “◯” indicates that local corrosion did not occur in the carbon dioxide environment, and “x” indicates that it did. Further, in Table 2, those in which the test piece did not break in the hydrogen sulfide corrosion test are shown by "◯", and those that did break were shown by "x".
【００４３】[0043]
【表１】 [Table 1]
【００４４】[0044]
【表２】 [Table 2]
【００４５】表１および表２において、試料No.1〜試料
No.15 は、いずれも、本発明で規定する条件を全て満足
する本発明例である。これらの試料No.1〜試料No.15
は、いずれも、マルテンサイト率：95％以上、0.5 ％伸
びでの耐力：552MPa以上であって、炭酸ガス環境下での
局部腐食性能が優れるとともに、耐硫化水素腐食性能に
優れる。このため、炭酸ガス環境下で局部腐食を生じ
ず、かつ、硫化水素環境下でも破断しない。このため、
硫化水素や炭酸ガスを含有する極めて腐食環境の厳しい
油井で使用されるCr含有油井管用鋼として、極めて好適
である。In Tables 1 and 2, sample No. 1 to sample
No. 15 is an example of the present invention that satisfies all the conditions specified in the present invention. Sample No. 1 to Sample No. 15
All have a martensite ratio of 95% or more and a proof stress at 0.5% elongation of 552 MPa or more, and have excellent local corrosion performance in a carbon dioxide gas environment and excellent hydrogen sulfide corrosion resistance. For this reason, local corrosion does not occur in a carbon dioxide gas environment, and it does not break even in a hydrogen sulfide environment. For this reason,
It is extremely suitable as a Cr-containing steel for oil country tubular goods that is used in oil wells containing hydrogen sulfide and carbon dioxide in a severely corrosive environment.
【００４６】これに対し、試料No.16 〜試料No.24 は、
比較例の試料である。試料No.16 は、Cr含有量が本発明
の範囲の下限を下回っているため、炭酸ガス環境下で局
部腐食が発生した。On the other hand, sample No. 16 to sample No. 24 are
It is a sample of a comparative example. In sample No. 16, the Cr content was below the lower limit of the range of the present invention, so that local corrosion occurred in the carbon dioxide gas environment.
【００４７】試料No.17 〜試料No.21 は、焼入れまま、
または焼なましままの組織のマルテンサイト率が95％未
満であるため、十分な炭酸ガス環境下での耐局部腐食性
能を示さなかった。Sample No. 17 to Sample No. 21 were
Alternatively, since the martensite ratio of the as-annealed structure was less than 95%, it did not show sufficient local corrosion resistance in a carbon dioxide environment.
【００４８】試料No.22 および試料No.23 は、いずれ
も、マルテンサイト率95％以上を確保するために炭酸ガ
ス環境下での耐局部腐食性能を確保することはできた
が、Ｂ含有量が本発明の範囲を外れているために耐硫化
水素性能が不足した。Both sample No. 22 and sample No. 23 were able to secure local corrosion resistance in a carbon dioxide environment in order to secure a martensite ratio of 95% or more, but the B content was However, the hydrogen sulfide resistance was insufficient because it was out of the range of the present invention.
【００４９】さらに、試料No.24 は、Ｂ含有量が本発明
の範囲外であるとともに、マルテンサイト率が95％未満
であるため、炭酸ガス環境下での耐局部腐食性能と耐硫
化水素腐食性能とがともに不充分であることがわかる。Further, in the sample No. 24, the B content is out of the range of the present invention and the martensite ratio is less than 95%. Therefore, the local corrosion resistance and the hydrogen sulfide corrosion resistance in the carbon dioxide environment are high. It can be seen that both performance and performance are insufficient.
【００５０】さらに、図１は、本実施例のデータに基づ
いて作成された、炭酸ガス環境下での局部腐食性能に及
ぼすCr添加量とマルテンサイト率との関係を示すグラフ
である。図１に示すグラフから、Cr含有量が1.0 ％以上
9.0 ％以下であって、マルテンサイト率が95％以上であ
れば、局部腐食が発生しないことがわかる。Further, FIG. 1 is a graph showing the relationship between the amount of Cr added and the martensite ratio on the local corrosion performance in a carbon dioxide gas environment, which was prepared based on the data of this example. From the graph shown in Fig. 1, the Cr content is 1.0% or more.
It can be seen that local corrosion does not occur when the martensite ratio is 9.0% or less and the martensite ratio is 95% or more.
【００５１】また、図２は、本実施例のデータに基づい
て作成された、Cr含有量4.87〜5.01％、マルテンサイト
率95％以上の鋼について、耐硫化水素腐食性能とＢ添加
量との関係を示すグラフである。図２に示すグラフか
ら、Ｂ添加量が0.0001％以上0.0020％以下であれば、耐
硫化水素腐食性能が優れることがわかる。Further, FIG. 2 shows the hydrogen sulfide corrosion resistance and the B addition amount for steels having a Cr content of 4.87 to 5.01% and a martensite ratio of 95% or more prepared based on the data of this example. It is a graph which shows a relationship. From the graph shown in FIG. 2, it can be seen that the hydrogen sulfide corrosion resistance is excellent when the B addition amount is 0.0001% or more and 0.0020% or less.
【００５２】[0052]
【発明の効果】以上詳細に説明したように、本発明によ
れば、耐硫化水素腐食性能と耐炭酸ガス腐食性能とがと
もに優れた552MPa以上の耐力を有するCr含有油井管用鋼
を提供することができた。かかる効果を有する本発明の
意義は、極めて著しい。As described in detail above, according to the present invention, there is provided a Cr-containing steel for oil country tubular goods having a proof stress of 552 MPa or more which is excellent in both hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance. I was able to. The significance of the present invention having such an effect is extremely remarkable.
【図１】炭酸ガス環境下での局部腐食性能に及ぼすCr添
加量とマルテンサイト率との関係を示すグラフである。FIG. 1 is a graph showing the relationship between the amount of Cr added and the martensite ratio on the local corrosion performance in a carbon dioxide gas environment.
【図２】Cr含有量4.87〜5.01％、マルテンサイト率95％
以上の鋼について、耐硫化水素耐食性能とＢ添加量との
関係を示すグラフである。[Fig. 2] Cr content 4.87 to 5.01%, martensite ratio 95%
It is a graph which shows the relationship between hydrogen sulfide corrosion resistance performance and B addition amount about the above steel.
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) C22C 38/00 - 38/60 ─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. 7 , DB name) C22C 38/00-38/60
Claims (4)
％、 Ｐ：0.03％以下、Ｓ：0.01％以下、Cr：1.0 〜9.0 ％、 Al：0.01〜0.10％、Ni：0.01〜0.50％、Ｂ：0.0001〜0.
0020％、 残部Feおよび不可避的不純物からなる鋼組成を有し、マ
ルテンサイト率が95％以上であり、552MPa以上の耐力を
有することを特徴とする耐硫化水素腐食性および耐炭酸
ガス腐食性能に優れたCr含有油井管用鋼。1. By weight%, C: 0.08 to 0.30%, Si: 0.1 to 1.0%, Mn: 0.1 to 3.0.
%, P: 0.03% or less, S: 0.01% or less, Cr: 1.0 to 9.0%, Al: 0.01 to 0.10%, Ni: 0.01 to 0.50%, B: 0.0001 to 0.
0020%, the balance of Fe and inevitable impurities steel composition, martensite ratio is 95% or more, and has a proof stress of 552 MPa or more, hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance Excellent Cr-containing steel for oil country tubular goods.
％、 Ｐ：0.03％以下、Ｓ：0.01％以下、Cr：1.0 〜9.0 ％、 Al：0.01〜0.10％、Ni：0.01〜0.50％、Ｂ：0.0001〜0.
0020％、 残部Feおよび不可避的不純物からなる鋼組成を有し、熱
間成形後の急冷または徐冷後のマルテンサイト率が95％
以上であって、さらにAc1 点以下の温度域での焼戻し後
の耐力が552MPa以上であることを特徴とする耐硫化水素
腐食性および耐炭酸ガス腐食性能に優れたCr含有油井管
用鋼。2. By weight%, C: 0.08 to 0.30%, Si: 0.1 to 1.0%, Mn: 0.1 to 3.0.
%, P: 0.03% or less, S: 0.01% or less, Cr: 1.0 to 9.0%, Al: 0.01 to 0.10%, Ni: 0.01 to 0.50%, B: 0.0001 to 0.
0020%, steel composition consisting of balance Fe and unavoidable impurities, and the martensite ratio after quenching after hot forming or 95% after quenching
Above, further, the Cr-containing steel for oil country tubular goods excellent in hydrogen sulfide corrosion resistance and carbon dioxide corrosion resistance, characterized in that the yield strength after tempering in the temperature range of Ac 1 point or less is 552 MPa or more.
る請求項１または請求項２に記載の耐硫化水素腐食性お
よび耐炭酸ガス腐食性能に優れたCr含有油井管用鋼。3. A Cr-containing steel for oil country tubular goods which is excellent in hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance according to claim 1 or 2, further containing Mo: 0.05 to 0.3% by weight.
から選ばれた１種または２種以上を、0.001 〜0.05重量
％含有する請求項１から請求項３までのいずれか１項に
記載の耐硫化水素腐食性および耐炭酸ガス腐食性能に優
れたCr含有油井管用鋼。4. The method according to claim 1, further comprising 0.001 to 0.05% by weight of one or more selected from the group consisting of Ca, Mg, La and Ce. Cr-containing steel for oil country tubular goods having excellent hydrogen sulfide corrosion resistance and carbon dioxide gas corrosion resistance as described.
Priority Applications (1)
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|---|---|---|---|
| JP23264699A JP3451993B2 (en) | 1999-08-19 | 1999-08-19 | Cr-containing steel for oil country tubular goods with excellent corrosion resistance to hydrogen sulfide and carbon dioxide |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23264699A JP3451993B2 (en) | 1999-08-19 | 1999-08-19 | Cr-containing steel for oil country tubular goods with excellent corrosion resistance to hydrogen sulfide and carbon dioxide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001059136A JP2001059136A (en) | 2001-03-06 |
| JP3451993B2 true JP3451993B2 (en) | 2003-09-29 |
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| CN106929774B (en) * | 2017-03-14 | 2018-08-28 | 达力普石油专用管有限公司 | A kind of normalizing state X52 sulfur resistive seamless line pipes and preparation method thereof |
| CN109402507A (en) * | 2018-11-07 | 2019-03-01 | 林州凤宝管业有限公司 | A kind of 80 steel level oil bushing of anti-H 2 S stress corrosion and its manufacturing method |
| CN115369316A (en) * | 2021-05-21 | 2022-11-22 | 宝山钢铁股份有限公司 | High-strength seamless steel tube with excellent carbon dioxide corrosion resistance and manufacturing method thereof |
| CN115386808B (en) * | 2022-09-28 | 2023-05-30 | 延安嘉盛石油机械有限责任公司 | Corrosion-resistant oil casing and preparation method and application thereof |
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