JPH06172859A - Production of high strength steel tube excellent in sulfide stress corrosion cracking resistance - Google Patents

Production of high strength steel tube excellent in sulfide stress corrosion cracking resistance

Info

Publication number
JPH06172859A
JPH06172859A JP32520292A JP32520292A JPH06172859A JP H06172859 A JPH06172859 A JP H06172859A JP 32520292 A JP32520292 A JP 32520292A JP 32520292 A JP32520292 A JP 32520292A JP H06172859 A JPH06172859 A JP H06172859A
Authority
JP
Japan
Prior art keywords
steel tube
billet
steel pipe
less
seamless steel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP32520292A
Other languages
Japanese (ja)
Inventor
Yoshiro Kuriki
良郎 栗木
Yusuke Minami
雄介 南
Shuji Hashizume
修司 橋爪
Yoshikazu Ishizawa
嘉一 石沢
Original Assignee
Nkk Corp
日本鋼管株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nkk Corp, 日本鋼管株式会社 filed Critical Nkk Corp
Priority to JP32520292A priority Critical patent/JPH06172859A/en
Publication of JPH06172859A publication Critical patent/JPH06172859A/en
Pending legal-status Critical Current

Links

Abstract

PURPOSE:To obtain the steel tube by directly working a continuously cast billet into a seamless steel tube, combinedly applying direct hardening to the steel tube, and specifying the composition of the steel tube. CONSTITUTION:A billet having a composition which consists of, by weight, 0.15-0.4% C, 0.1-1% Si, 0.3-1% Mn, 0.1-1.5% Cr, 0.1-1% Mo, <=0.015% P, <=0.005% S, 0.0005-0.003% B, 0.01-0.1% Al, 0.01-0.03% Ti, 0.003-0.01% N, and the balance Fe and where, when a PGS value represented by equation PGS=(0.3Ti+0.05Al)/N is determined, the contents of Al, Ti, and N are regulated so that PGS becomes 1.0 to 1.5 is prepared. This billet is worked at a temp. not lower than the Ac3 transformation point into a seamless steel tube, which is subjected, without delay, to water quenching and to tempering at a temp. not higher than the Ac1 transformation point. Moreover, Nb and/or V can further be incorporated by 0.01-0.05% into the above composition. By this method, the seamless steel tube for oil well and gas well use, excellent in SSCC resistance and having strength as high as >=75kg/mm<2> yield point strength can be obtained.

Description

【発明の詳細な説明】Detailed Description of the Invention
【0001】[0001]
【産業上の利用分野】本発明は、特に湿潤硫化水素と応
力の組み合わされた環境下で発生する硫化物応力腐食割
れ(以下SSCCと略する) に対し高い抵抗性を有し、
降伏強度が75Kgf/mm2 以上の高強度を有する油
井あるいはガス井用シームレス鋼管を製造する方法に関
するものである。
The present invention has a high resistance to sulfide stress corrosion cracking (hereinafter abbreviated as SSCC) which occurs particularly in an environment in which wet hydrogen sulfide and stress are combined.
The present invention relates to a method for producing a seamless steel pipe for oil wells or gas wells having a high yield strength of 75 Kgf / mm 2 or more.
【0002】[0002]
【従来の技術】近年のエネルギー事情の逼迫に伴い、こ
れまで開発されていない深層部でかつ硫化水素を含む油
井又はガス井も開発の対象となり、これらに使用する油
井管として高強度と、SSCCに対する高い抵抗性を具
備したシームレス鋼管の製造が強く望まれている。
2. Description of the Related Art Due to the recent tight energy situation, deep wells and hydrogen wells containing hydrogen sulfide, which have not been developed up to now, are also targeted for development, and high strength and SSCC are used as the oil well pipes used for these There is a strong demand for the production of seamless steel pipes with high resistance to
【0003】油井管として使用される鋼管は通常一回の
焼入れ焼戻しの熱処理が施されているが、これまでの経
験からSSCCを防止するには、硬度をロックウェルC
スケールで20〜22以下に規制することが有効とされ
ている。
Steel pipes used as oil well pipes are usually subjected to a single heat treatment of quenching and tempering, but experience shows that in order to prevent SSCC, the hardness is Rockwell C.
It is effective to regulate the scale to 20 to 22 or less.
【0004】しかし、この硬度の規制に従うと降伏強度
は高々70Kgf/mm2 とせざるを得ず、それ以上の
高強度と耐SSCC性を兼ね備えた鋼管を製造すること
は困難であった。
However, according to this regulation of hardness, the yield strength has to be at most 70 Kgf / mm 2, and it has been difficult to manufacture a steel pipe having higher strength and SSCC resistance.
【0005】一方、耐SSCC性の評価方法としては米
国におけるNACEの規格TM−01−77に定められ
ている硫化水素飽和5%NaCl−0.5%酢酸水溶液
中での定荷重引張試験がよく知られている。ここに規定
されているSSCCを発生しない最高応力と材料の公称
降伏応力との比を百分率で表した「割れ限界比(σth
/YS) 」で85%以上の耐SSCCと降伏強度75K
gf/mm2 以上の高強度を両立させる方法として結晶
粒の微細化が有効であることが知られている。
On the other hand, as a method for evaluating the SSCC resistance, a constant load tensile test in a 5% saturated aqueous solution of hydrogen sulfide, NaCl-0.5% acetic acid, which is defined in the NACE standard TM-01-77 in the United States, is often used. Are known. The "cracking limit ratio (σth
/ YS) ”, SSCC resistance of 85% or more and yield strength of 75K
It is known that miniaturization of crystal grains is effective as a method for achieving both high strength of gf / mm 2 or more.
【0006】これを具体化するための方策として、特開
昭59−232220号公報に開示されているように、
製造された鋼管に対し、焼入れ、焼戻しの処理を2回以
上施すもの、あるいは特開昭59−119324号公報
に開示されているように、焼入れ処理前の昇温温度を著
しく大とする方法が提案されている。
As a measure for embodying this, as disclosed in JP-A-59-232220,
The manufactured steel pipe is subjected to quenching and tempering treatments twice or more, or as disclosed in JP-A-59-119324, a method of significantly increasing the temperature rise before quenching treatment is used. Proposed.
【0007】一方、油井あるいはガス井に用いられるシ
ームレス鋼管(継ぎ目なし鋼管)は、近年省エネルギ
ー、省コストの観点から、例えば特開昭57−3912
9号公報に開示されている通り、熱間でのパイプ圧延後
その保有する温度を利用してAc3 点以上の温度から水
焼入れし、しかる後に焼戻しを行うことが行われてい
る。この方法はいわゆる直接焼入れ法と呼ばれ、最近で
は多く利用されている。ところが、パイプ圧延後室温温
度まで冷却し、再加熱によって所定の焼入れ温度まで昇
温させ、続いて焼入れを行う従前のパイプ製造法に比
べ、直接焼入れにより製造されたパイプは、オーステナ
イト→フェライト変態及びその逆方向の変態過程が省略
されるため結晶粒が粗大化する傾向を示し、そのため耐
SSCC性が劣化することは避けられなかった。
On the other hand, seamless steel pipes (seamless steel pipes) used for oil wells or gas wells have recently been disclosed in, for example, JP-A-57-3912 from the viewpoint of energy saving and cost saving.
As disclosed in Japanese Patent Publication No. 9, gazette, after hot pipe rolling, water quenching is performed from a temperature of Ac 3 or higher by utilizing the temperature held by the pipe, and then tempering is performed. This method is called the so-called direct quenching method and has been widely used recently. However, compared to the conventional pipe manufacturing method in which the pipe is cooled to room temperature after rolling, heated to a predetermined quenching temperature by reheating, and then quenched, the pipe manufactured by direct quenching has austenite-ferrite transformation and Since the transformation process in the opposite direction is omitted, the crystal grains tend to be coarsened, and thus the SSCC resistance is unavoidably deteriorated.
【0008】[0008]
【発明が解決しようとする課題】以上述べたように、直
接焼入れによって製造されるシームレス鋼管はエネルギ
ーあるいはコストの面では有利であるが、結晶粒径が粗
大化する傾向にあるため耐SSCCを要求される油井あ
るいはガス井に使用される鋼管に適用することは困難と
されていた。
As described above, the seamless steel pipe manufactured by direct quenching is advantageous in terms of energy and cost, but it requires SSCC resistance because the crystal grain size tends to become coarse. It has been considered difficult to apply it to steel pipes used in oil wells or gas wells.
【0009】従って、本発明は直接焼入れ後焼戻し処理
をすることによっても優れた耐SSCC性を具備する高
強度シームレス鋼管を製造する方法に関するものであ
る。具体的には連続鋳造によって鋳造されたビレットを
直接シームレス鋼管に加工し、これを直接焼入れするプ
ロセスと組合わせ、さらに鋼管の化学成分組成を特定の
範囲に限定することによって優れた耐SSCCと降伏点
強度75Kgf/mm2以上の高強度を実現することを
目的とするものである。
Accordingly, the present invention relates to a method for producing a high-strength seamless steel pipe having excellent SSCC resistance even by performing direct quenching and then tempering. Specifically, the billet cast by continuous casting is directly processed into a seamless steel pipe, which is combined with a process of direct quenching, and by limiting the chemical composition of the steel pipe to a specific range, excellent SSCC resistance and yield The purpose is to achieve high strength of 75 Kgf / mm 2 or more in point strength.
【0010】かかる本発明の製造方法は省エネルギー、
省コストを実現し、かつ設備コストあるいは生産コスト
を格段に要しない点で従来の製造法に利点を有するもの
である。
The manufacturing method of the present invention is energy saving,
This is an advantage over the conventional manufacturing method in that the cost saving is realized and the facility cost or the production cost is not required significantly.
【0011】[0011]
【課題を解決するための手段】[Means for Solving the Problems]
(1)下記の工程を備えた耐硫化物応力腐食割れ性に優
れた高強度鋼管の製造方法(成分組成はwt%であ
る)。 (a)C:0.15〜0.4 % 、 Si:0.1〜1 % 、
Mn:0.3 〜1 % 、Cr:0.1〜1.5 % 、 Mo:0.1〜1 %
、 P:0.015 % 以下、S:0.005%以下、
B:0.0005〜0.003%、 Al:0.01〜0.1 % 、Ti:0.01
〜0.03 %、 N:0.003 〜0.01 % 、 Al, TiおよびNの含有量は、下式に示すPGS値を定めた
とき、 PGS=(0.3Ti+0.05Al) /N PGSが1.0 以上でかつ1.5 以下であり、残部がFeと不可
避不純物からなる成分組成の連続鋳造ビレットを用意す
る工程と、(b) 前記ビレットをAc3 変態点以上の温度
でシームレス鋼管に加工し、直ちにこれを水焼入れを行
う工程と、(c) 水焼入れした前記シームレス鋼管をAc
1 変態点以下の温度で焼戻す工程。
(1) A method for producing a high-strength steel pipe excellent in sulfide stress corrosion cracking resistance, which comprises the following steps (the composition of the composition is wt%). (A) C: 0.15 to 0.4%, Si: 0.1 to 1%,
Mn: 0.3-1%, Cr: 0.1-1.5%, Mo: 0.1-1%
, P: 0.015% or less, S: 0.005% or less,
B: 0.0005 to 0.003%, Al: 0.01 to 0.1%, Ti: 0.01
~0.03%, N: 0.003 ~0.01% , Al, the content of Ti and N, when established the P GS values shown in the following equation, in P GS = (0.3Ti + 0.05Al) / N P GS is 1.0 or more And a ratio of 1.5 or less, and the balance is Fe and inevitable impurities, and a step of preparing a continuously cast billet having a composition of components, and (b) the billet is processed into a seamless steel pipe at a temperature of an Ac 3 transformation point or higher, and immediately formed into water. The process of quenching, and (c) the water-quenched seamless steel pipe is
Step of tempering at a temperature below 1 transformation point.
【0012】(2)下記の工程を備えた耐硫化物応力腐
食割れ性に優れた高強度鋼管の製造方法(成分組成はw
t%である)。 (a)C:0.15〜0.4 % 、 Si:0.1〜1 % 、
Mn:0.3 〜1 % 、Cr:0.1〜1.5 % 、 Mo:0.1〜1 %
、 P:0.015 %以下、S:0.005%以下、
B:0.0005〜0.003%、 Al:0.01〜0.1 % 、Ti:0.01 〜
0.03 %、 N:0.003 〜0.01 %、 Al, TiおよびN含有量は下式で示すPGS値を定めたと
き、 PGS=(0.3Ti+0.05Al) /N PGSが1.0 以上でかつ1.5 以下であり、更に、 Nb:0.01
〜0.05 %、及びV:0.01〜0.05 %のうち1種以上を含有し
残部がFeと不可避不純物からなる成分組成の連続鋳造ビ
レットを用意する工程と、(b)前記ビレットをAc3
態点以上の温度でシームレス鋼管に加工し直ちに水焼入
れを行う工程と、(c) 水焼入れした前記シームレス鋼
管をAc1 変態点以下の温度で焼戻す工程。
(2) A method for producing a high-strength steel pipe having excellent resistance to sulfide stress corrosion cracking, which comprises the following steps (component composition: w
t%). (A) C: 0.15 to 0.4%, Si: 0.1 to 1%,
Mn: 0.3-1%, Cr: 0.1-1.5%, Mo: 0.1-1%
, P: 0.015% or less, S: 0.005% or less,
B: 0.0005-0.003%, Al: 0.01-0.1%, Ti: 0.01-
0.03%, N: 0.003 ~0.01% , Al, when Ti and N content that defines the P GS value indicated by the following formula, P GS = (0.3Ti + 0.05Al ) / N P GS is and 1.5 or less than 1.0 And further, Nb: 0.01
-0.05% and V: 0.01-0.05%, and a step of preparing a continuously cast billet having a composition of the composition that the balance is Fe and inevitable impurities, and (b) the billet has an Ac 3 transformation point or more. The step of processing the seamless steel pipe at the temperature of 1. and immediately water quenching, and (c) the step of tempering the water-quenched seamless steel pipe at a temperature below the Ac 1 transformation point.
【0013】[0013]
【作用】本発明に係るシームレス鋼管の製造方法の特徴
は、省エネルギー、省コストの観点から、直接焼入れお
よび焼戻しによる製造を採用する一方、この場合におい
ても微細な結晶粒を有し、優れた耐SSCCを具備する
シームレス鋼管の製造方法である。この特徴を実現する
ための方策を種々検討した結果以下のような製造方法を
発明した。
The feature of the method for producing a seamless steel pipe according to the present invention is that the production by direct quenching and tempering is adopted from the viewpoint of energy saving and cost saving. It is a manufacturing method of a seamless steel pipe provided with SSCC. As a result of various studies on measures for realizing this feature, the following manufacturing method was invented.
【0014】すなわち、後述する成分組成の鋼におい
て、PGS=(0.3Ti +0.05Al) /Nなるパラメータを用
いて、Ti,N及びAlの量を特定の範囲に限定するこ
とによって、直接焼入れ材においても微細な結晶粒度に
なることを見い出した。さらに、結晶粒径のより微細化
を図るためには、NbおよびVのうち1種以上を添加す
る。また、本発明においては、主にTiの窒化物による
結晶粒抑制効果によるものであることから、TiNを鋼
中に微細に析出させる必要がある。このためシームレス
鋼管の素材となるビレットは連続鋳造法によることを必
須とする。
That is, in the steel having the composition as described below, direct quenching is performed by using the parameter P GS = (0.3Ti + 0.05Al) / N to limit the amounts of Ti, N and Al within a specific range. It has been found that the grain size of the material is also fine. Further, in order to further reduce the crystal grain size, at least one of Nb and V is added. Further, in the present invention, it is necessary to finely precipitate TiN in the steel because it is mainly due to the effect of suppressing the crystal grains by the nitride of Ti. For this reason, it is essential that the billet, which is the material of the seamless steel pipe, be produced by the continuous casting method.
【0015】連続鋳造法によるビレットは、通常丸ビレ
ットを使用するが、角型又は多角形のビレットでも直接
穿孔出来るビレットであればよい。連続鋳造法により製
造されたビレットにおいては、ビレットは鋳造後直ちに
水冷されるために冷却速度は数℃/分であるため、凝固
速度が速い。従って析出するTiNは1μm以下のサイ
ズであり、析出個数も多く、結晶粒の微細化に効果があ
る。
As the billet produced by the continuous casting method, a round billet is usually used, but a square or polygonal billet may be used as long as it can be directly perforated. In the billet manufactured by the continuous casting method, the billet is water-cooled immediately after casting, so that the cooling rate is several degrees centigrade / minute, so that the solidification rate is high. Therefore, the TiN to be deposited has a size of 1 μm or less, the number of deposited TiN is large, and it is effective for refining the crystal grains.
【0016】なお、連続鋳造ビレットは初析オーステナ
イトが鋼塊材よりも細かいので、この点でも加工された
シームレス鋼管の結晶粒度を微細化している。一方、造
塊・分塊法で製造されたビレットは、造塊時における冷
却速度は数十℃/分であり、初析オーステナイトも粗粒
であると共に、析出しているTiNは数μmのサイズで
あるため、結晶粒の微細化に効果がなく、また靱性も劣
化させる。以下、本発明において鋼の成分組成を上記の
ように限定した理由について述べる。
Since the pro-eutectoid austenite of the continuously cast billet is finer than that of the steel ingot, the grain size of the processed seamless steel pipe is also miniaturized in this respect as well. On the other hand, the billet manufactured by the ingot-casting method has a cooling rate of several tens of degrees Celsius per minute during ingot casting, and the pro-eutectoid austenite is also coarse particles, and the precipitated TiN has a size of several μm. Therefore, it has no effect on the refinement of crystal grains and also deteriorates the toughness. Hereinafter, the reasons why the composition of the steel is limited as described above in the present invention will be described.
【0017】C:0.15〜0.4%とする。 Cは低合金鋼の強度を確保する作用のほか、焼入れ性や
焼戻し抵抗を向上させるための必須な元素として、その
含有量を0.15%以上とした。しかし、0.4%を超
える多量の含有量は焼入れ時に割れを生じたり、靱性の
劣化を招いたりすることとなるので、C含有量を上記の
範囲とする。
C: 0.15 to 0.4% C is an essential element for improving the hardenability and the tempering resistance in addition to the function of ensuring the strength of the low alloy steel, and its content is set to 0.15% or more. However, a large content exceeding 0.4% causes cracks during quenching and deterioration of toughness, so the C content is set to the above range.
【0018】S:0.1〜1%とする。 Siは鋼の脱酸剤としての作用のほか、鋼材の強度を向
上させる作用があるので、0.1%以上の添加を必要と
するが、1%を超えて含有させると靱性の劣化をきた
し、粒界強度も減少させるのでその上限を1%とする。
S: 0.1 to 1% Si has a function as a deoxidizing agent for steel, as well as a function for improving the strength of the steel material, so it is necessary to add 0.1% or more, but if it exceeds 1%, toughness deteriorates. Since the grain boundary strength is also reduced, its upper limit is set to 1%.
【0019】Cr:0.1〜1.5%とする。 Crは焼入れ性の向上に著しく効果を示す元素で、鋼の
強度も増加せしめる作用があるが、その含有量が0.1
%未満では前記作用に所望の効果を得ることができず、
多量に添加すると明らかに耐SSCCを低下させるので
その上限を1.5%とする。
Cr: 0.1 to 1.5% Cr is an element that has a significant effect on the improvement of hardenability, and has the effect of increasing the strength of steel, but its content is 0.1.
If it is less than%, the desired effect cannot be obtained in the above action,
Since the SSCC resistance is obviously lowered when added in a large amount, the upper limit is made 1.5%.
【0020】Mo:0.1〜1%とする。 Moには鋼の焼戻し抵抗を高める作用があるが、0.1
%以下ではその効果が小さく、他方1%を超えて含有さ
せると鋼の脆化や靱性の劣化をきたすようになることか
らMoの含有量は上記範囲とする。
Mo: 0.1 to 1%. Mo has the effect of increasing the tempering resistance of steel, but 0.1
%, The effect is small. On the other hand, if the content exceeds 1%, the steel becomes brittle and the toughness deteriorates. Therefore, the Mo content is in the above range.
【0021】P:0.015%以下とする。 Pは粒界強度を低下させる有害な元素であり、特にその
含有量が0.015%を超えると耐SSCC性が劣化す
ることから、その含有量を0.015%以下とする。
P: 0.015% or less. P is a harmful element that lowers the grain boundary strength, and particularly when its content exceeds 0.015%, the SSCC resistance deteriorates, so its content is made 0.015% or less.
【0022】S:0.005%以下とする。 Sは鋼中の不可避な不純物であり、多量に含むとMnS
を形成しこれが割れの起点となる。従って、Sの含有量
は0.005%以下とする。
S: 0.005% or less. S is an unavoidable impurity in steel, and if contained in a large amount, MnS
Is formed, and this becomes the starting point of cracking. Therefore, the S content is set to 0.005% or less.
【0023】B:0.0005%〜0.003%とす
る。 Bは鋼の焼入れ性を向上し、0.005%以上含有させ
ることができるが、多量に添加してもその効果が飽和す
るのみならず、熱間加工時の割れを生じることからBの
含有量は上記範囲とする。
B: 0.0005% to 0.003%. B improves the hardenability of steel and can be contained in an amount of 0.005% or more. However, the addition of a large amount not only saturates the effect, but also causes cracking during hot working, so B is included. The amount is in the above range.
【0024】Al:0.01〜0.1%とする。 Alは鋼の脱酸剤として有用な元素であり、Tiとなら
んで鋼中のNと結合して窒化物を形成し、Bの作用を顕
在化させる元素であり、その含有量を0.01%以上と
する。また、0.1%を超える過剰な含有量はAl2
3 を増加させ、耐SSCCを低下させることからAlの
含有量は0.01〜0.1%とする。
Al: 0.01 to 0.1%. Al is an element useful as a deoxidizing agent for steel, is an element that combines with Ti to form N by combining with N in the steel to form a nitride, and makes the effect of B manifest 0.01. % Or more. Further, an excessive content exceeding 0.1% is Al 2 O.
3 is increased and the SSCC resistance is lowered, so the Al content is made 0.01 to 0.1%.
【0025】Ti:0.01〜0.03%とする。 TiはAlと同様にNをTiNとして固定し、Bの焼入
れ性向上を図り、かつ連続鋳造法で鋳造されたビレット
中では微細に分散析出するため、ビレット加熱時の結晶
粒の粗大化を抑制する効果がある。しかし、その含有量
が0.01%未満では前記所望の効果を得ることができ
ず、他方0.03%を超えて含有させると、TiNの凝
集粗大化によって結晶粒成長の抑制に効果がないばかり
か靱性の劣化を招くことになるのでTi含有量を0.0
1〜0.03%とする。
Ti: 0.01 to 0.03%. Ti fixes N as TiN like Al, improves the hardenability of B, and finely disperses and precipitates in the billet cast by the continuous casting method, thus suppressing coarsening of crystal grains during billet heating. Has the effect of However, if the content is less than 0.01%, the desired effect cannot be obtained. On the other hand, if the content exceeds 0.03%, there is no effect in suppressing the crystal grain growth due to coarsening of TiN by aggregation. Not only this causes deterioration of toughness, so the Ti content is 0.0
1 to 0.03%.
【0026】N:0.003〜0.01%とする。 NはTiおよびAlと窒化物を形成し、特にTiNは鋼
の粒成長を抑制し、微細化する作用がある。従って、添
加したTiを結晶粒微細化に有効に作用するTiNとし
て鋼中に析出させるためには、化学量論的考慮から、
0.003%以上とする。他方0.01%を超えて含有
させると、B添加の効果を減少し、焼入れ性劣化を招く
ようになるので、N含有量を0.003〜0.01%と
する。以上が請求項1の成分組成の作用である。
N: 0.003 to 0.01%. N forms a nitride with Ti and Al, and particularly TiN has a function of suppressing grain growth of steel and refining it. Therefore, in order to precipitate the added Ti in the steel as TiN that effectively acts on the grain refinement, in consideration of stoichiometry,
It is made 0.003% or more. On the other hand, if the content is more than 0.01%, the effect of B addition is reduced and the hardenability is deteriorated. Therefore, the N content is set to 0.003 to 0.01%. The above is the effect of the component composition of claim 1.
【0027】NbおよびV:共に0.01%〜0.05
%とする。 NbおよびVは圧延中の再結晶粒を細かくする効果を有
するため、より微細な結晶粒を所望する場合添加する元
素であり、請求項1の成分組成に更にこれらの元素を含
有する場合が請求項2の成分組成である。この効果は
0.01%未満では十分でなく、0.05%を超えても
その効果が飽和するばかりか、靱性の低下を招くことか
ら、両元素の含有量を共に0.01%〜0.05%とす
る。
Nb and V: 0.01% to 0.05 for both
%. Since Nb and V have an effect of making recrystallized grains fine during rolling, they are elements to be added when a finer crystal grain is desired, and when the element composition of claim 1 further contains these elements, It is the component composition of Item 2. This effect is not sufficient if it is less than 0.01%, and if it exceeds 0.05%, not only the effect is saturated but also the toughness is lowered, so that the content of both elements is 0.01% to 0%. 0.05%.
【0028】さらに、既に述べたように、本発明におい
てはTiNの析出により鋼の組織を微細化する必要があ
ることから、AlNをも含めた鋼中の窒化物の総量を化
学量論比を考慮して最適化する必要がある。この観点か
らPGS=(0.3Ti+0.05Al) /Nなるパラメータを定めた
とき、図1に示すように、PGSが1.0未満あるいは
1.5を超えると結晶粒度ASTM No.8以下の粗
粒となることを見いだした。そこでPGSの値を1.0〜
1.5とする。
Further, as described above, since it is necessary to refine the structure of the steel by precipitation of TiN in the present invention, the total amount of nitrides in the steel including AlN is set to the stoichiometric ratio. It is necessary to consider and optimize. From this point of view, when the parameter P GS = (0.3Ti + 0.05Al) / N is determined, as shown in FIG. 1, when P GS is less than 1.0 or exceeds 1.5, the grain size ASTM No. It was found that the coarse particles were 8 or less. Therefore, the value of P GS is 1.0-
Set to 1.5.
【0029】焼戻し温度の上限は、フェライトを析出さ
せないため上限としてAc1 温度であるが、焼戻し温度の
下限は目的とする鋼管の強度により変化させればよい。
強度を低くする場合はこの温度を高くし、強度を高くす
る場合は低い温度で焼戻す。降伏点YSを約75Kgf
/mm2 とするためには約700 ℃で焼き戻せばよい。
The upper limit of the tempering temperature is the Ac 1 temperature as an upper limit so as not to precipitate ferrite, but the lower limit of the tempering temperature may be changed depending on the strength of the target steel pipe.
When lowering the strength, this temperature is increased, and when increasing the strength, tempering is performed at a lower temperature. Yield point YS is about 75 Kgf
/ Mm 2 can be tempered at about 700 ° C.
【0030】[0030]
【実施例】本発明の実施例について説明する。表1に示
す成分組成の鋼を用いて製造されたシームレス鋼管の特
性を、製造方法と合わせて表2に示す。本発明鋼は、連
続鋳造法(CC)によって製造したビレットを素材とし
てシームレスパイプの製造を行い、続いて直接焼入れ
(DQ)を行なった。連続鋳造のビレットの径は直径で
約170 〜300 mmである。また、シームレス鋼管の外径は
約114 〜244 mmであり、また肉厚は約10〜15mmである。
EXAMPLES Examples of the present invention will be described. The characteristics of the seamless steel pipe manufactured using the steel having the composition shown in Table 1 are shown in Table 2 together with the manufacturing method. For the steel of the present invention, a seamless pipe was manufactured using a billet manufactured by the continuous casting method (CC) as a raw material, and then direct quenching (DQ) was performed. The diameter of the billet for continuous casting is about 170 to 300 mm in diameter. The outer diameter of the seamless steel pipe is about 114 to 244 mm, and the wall thickness is about 10 to 15 mm.
【0031】シームレス鋼管の圧延方法は、マンネスマ
ン穿孔法とマンドレル圧延法とを組み合わせた。なお、
鋼の成分組成は最終製品であるシームレスパイプの結晶
粒が細粒化されるようにTi,AlおよびN量を最適化
して、PGSを1.0〜1.5としているため、結晶粒度
はいずれもASTM No.8以上の細粒化組織となっ
ていた。特に、Nb若しくはVを添加したB鋼、D鋼お
よびF鋼では、ASTM No.10の微細結晶粒が得
られていた。また発明鋼は表2に示した温度で焼戻しを
行うことによって75Kgf/mm2 以上の降伏強度を
示し、かつ割れ限度比(σth/YS)は0.85以上
の優れた耐SSCCを示した。
The seamless steel tube rolling method was a combination of the Mannesmann piercing method and the mandrel rolling method. In addition,
The composition of the steel is optimized by adjusting the amounts of Ti, Al and N so that the crystal grains of the seamless pipe, which is the final product, are refined, and the P GS is set to 1.0 to 1.5. Both are ASTM No. It had a fine-grained structure of 8 or more. In particular, in B steel, D steel and F steel to which Nb or V is added, ASTM No. 10 fine crystal grains were obtained. Further, the invention steels exhibited a yield strength of 75 Kgf / mm 2 or more by tempering at the temperatures shown in Table 2, and exhibited excellent SSCC resistance of the crack limit ratio (σth / YS) of 0.85 or more.
【0032】一方、連続鋳造(CC)と直接焼入れ(D
Q)の組み合わせで所望の特性を示したA鋼も、ビレッ
トを造塊・分塊法(CV)とした場合は、ASTM N
o.8以上の細粒組織は得ることができなかった。ここ
で造塊は7ton鋼塊で、これを分解圧延し、さらにビ
レット圧延したもので直径は230 〜300mm のものであっ
た。また、G鋼は表1に示すように、PGSの値が1.5
を上回っているため、CCとDQの組み合わせでパイプ
製造を行っても結晶粒度はNo.5にとどまった。
On the other hand, continuous casting (CC) and direct quenching (D
A steel that shows the desired properties in the combination of Q) is also ASTM N when the billet is made by the ingot-casting / clumping method (CV).
o. A fine grain structure of 8 or more could not be obtained. Here, the ingot was a 7 ton steel ingot, which was decomposed and rolled, and further billet rolled, and had a diameter of 230 to 300 mm. As shown in Table 1, G steel has a P GS value of 1.5.
Since it exceeds the above, even if pipes are manufactured with a combination of CC and DQ, the grain size is No. Stayed at 5.
【0033】H鋼においてはPGSの値は適正であるた
め、ASTM No.8の結晶細粒化は達成されたが、
CrおよびMo量が適正でないため、σth/YSは
0.5にとどまった。I鋼においては、CCとRQ(製
造されたシームレス鋼管を再熱し焼入れたもの)の組み
合わせでシームレス鋼管が製造された場合には、結晶粒
度ならびに耐SSCCも所望の特性を示すが、CCとD
Qとの組み合わせで製造された場合でも、PGSの値が
1.0を下回っているため結晶粒度ASTM No.8
を達することはできなかった。
Since the value of P GS is appropriate for H steel, the number of ASTM No. Although grain refinement of 8 was achieved,
Since the amounts of Cr and Mo were not proper, σth / YS remained at 0.5. In steel I, when a seamless steel pipe is manufactured by combining CC and RQ (a seamless steel pipe that has been reheated and quenched), the grain size and SSCC resistance also show the desired characteristics, but CC and D
Even when produced in combination with Q, the value of P GS is less than 1.0, so the grain size ASTM No. 8
Could not be reached.
【0034】[0034]
【表1】 [Table 1]
【0035】[0035]
【表2】 [Table 2]
【0036】[0036]
【発明の効果】このように本発明によるシームレス鋼管
の製造法によれば、高強度と耐硫化物応力腐食割れ性が
同時に高い水準であるシームレス鋼管が得られ、直接焼
入れ及び焼戻しの経済的メリットを最大に生かすことが
できる。これにより省エネルギーおよび省コストを達成
することができる。
As described above, according to the method for producing a seamless steel pipe of the present invention, a seamless steel pipe having a high strength and a high level of sulfide stress corrosion cracking resistance at the same time can be obtained, and the economic advantages of direct quenching and tempering are obtained. Can be maximized. Thereby, energy saving and cost saving can be achieved.
【図面の簡単な説明】[Brief description of drawings]
【図1】PGSというパラメータと結晶粒度の関連を示す
ものである。
FIG. 1 shows the relationship between the parameter P GS and grain size.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 石沢 嘉一 東京都千代田区丸の内一丁目1番2号 日 本鋼管株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaichi Ishizawa, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Steel Pipe Co., Ltd.

Claims (2)

    【特許請求の範囲】[Claims]
  1. 【請求項1】 下記の工程を備えた耐硫化物応力腐食割
    れ性に優れた高強度鋼管の製造方法(成分組成はwt%
    である)。 (a)C:0.15〜0.4 % 、 Si:0.1〜1 % 、
    Mn:0.3 〜1 % 、 Cr:0.1〜1.5 % 、 Mo:0.1〜1 % 、 P:0.0
    15 % 以下、 S:0.005%以下、 B:0.0005〜0.003%、 Al:0.
    01〜0.1 % 、 Ti:0.01 〜0.03 %、 N:0.003 〜0.01 % 、 Al, TiおよびNの含有量は、下式に示すPGS値を定めた
    とき、 PGS=(0.3Ti+0.05Al) /N PGSが1.0 以上でかつ1.5 以下であり、 残部がFeと不可避不純物からなる成分組成の連続鋳造ビ
    レットを用意する工程と、(b) 前記ビレットをAc3
    態点以上の温度でシームレス鋼管に加工し、直ちにこれ
    を水焼入れを行う工程と、(c) 水焼入れした前記シー
    ムレス鋼管をAc1 変態点以下の温度で焼戻す工程。
    1. A method for producing a high-strength steel pipe excellent in sulfide stress corrosion cracking resistance, which comprises the following steps (the composition of components is wt%:
    Is). (A) C: 0.15 to 0.4%, Si: 0.1 to 1%,
    Mn: 0.3-1%, Cr: 0.1-1.5%, Mo: 0.1-1%, P: 0.0
    15% or less, S: 0.005% or less, B: 0.0005 to 0.003%, Al: 0.
    01~0.1%, Ti: 0.01 ~0.03% , N: 0.003 ~0.01%, Al, the content of Ti and N, when established the P GS values shown in the following equation, P GS = (0.3Ti + 0.05Al ) / N P GS is 1.0 or more and 1.5 or less, and a step of preparing a continuously cast billet having a composition of the balance of Fe and inevitable impurities, and (b) seamless steel pipe for the billet at a temperature of Ac 3 transformation point or more. And a step of (c) tempering the water-quenched seamless steel pipe at a temperature not higher than the Ac 1 transformation point.
  2. 【請求項2】 下記の工程を備えた耐硫化物応力腐食割
    れ性に優れた高強度鋼管の製造方法(成分組成はwt%
    である)。 (a)C:0.15〜0.4 % 、 Si:0.1〜1 % 、
    Mn:0.3 〜1 % 、 Cr:0.1〜1.5 % 、 Mo:0.1〜1 % 、 P:0.0
    15 %以下、 S:0.005%以下、 B:0.0005〜0.003%、 Al:0.
    01〜0.1 % 、 Ti:0.01 〜0.03 %、 N:0.003 〜0.01 %、 Al, TiおよびN含有量は下式で示すPGS値を定めたと
    き、 PGS=(0.3Ti+0.05Al) /N PGSが1.0 以上でかつ1.5 以下であり、 更に、 Nb:0.01〜0.05 %、及びV:0.01〜0.05 %のうち1
    種以上を含有し、 残部がFeと不可避不純物からなる成分組成の連続鋳造ビ
    レットを用意する工程と、(b)前記ビレットをAc3
    態点以上の温度でシームレス鋼管に加工し、直ちに水焼
    入れを行う工程と、(c) 水焼入れした前記シームレス
    鋼管をAc1 変態点以下の温度で焼戻す工程。
    2. A method for producing a high-strength steel pipe excellent in sulfide stress corrosion cracking resistance, which comprises the following steps (component composition is wt%:
    Is). (A) C: 0.15 to 0.4%, Si: 0.1 to 1%,
    Mn: 0.3-1%, Cr: 0.1-1.5%, Mo: 0.1-1%, P: 0.0
    15% or less, S: 0.005% or less, B: 0.0005 to 0.003%, Al: 0.
    01~0.1%, Ti: 0.01 ~0.03% , N: 0.003 ~0.01%, Al, when Ti and N content that defines the P GS value indicated by the following formula, P GS = (0.3Ti + 0.05Al ) / N P GS is 1.0 or more and 1.5 or less, and 1 of Nb: 0.01 to 0.05% and V: 0.01 to 0.05%
    A step of preparing a continuously cast billet containing at least one species and the balance of which is Fe and inevitable impurities, and (b) processing the billet into a seamless steel pipe at a temperature of the Ac 3 transformation point or higher and immediately water quenching. And (c) a step of tempering the water-quenched seamless steel pipe at a temperature not higher than the Ac 1 transformation point.
JP32520292A 1992-12-04 1992-12-04 Production of high strength steel tube excellent in sulfide stress corrosion cracking resistance Pending JPH06172859A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
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Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
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Publication Number Publication Date
JPH06172859A true JPH06172859A (en) 1994-06-21

Family

ID=18174165

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Country Link
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