JP2002250480A - Antiseismic high-strength steel pipe for a pipeline of superior high speed ductile fracture characteristics - Google Patents
Antiseismic high-strength steel pipe for a pipeline of superior high speed ductile fracture characteristicsInfo
- Publication number
- JP2002250480A JP2002250480A JP2001046043A JP2001046043A JP2002250480A JP 2002250480 A JP2002250480 A JP 2002250480A JP 2001046043 A JP2001046043 A JP 2001046043A JP 2001046043 A JP2001046043 A JP 2001046043A JP 2002250480 A JP2002250480 A JP 2002250480A
- Authority
- JP
- Japan
- Prior art keywords
- ductile fracture
- steel pipe
- strength steel
- antiseismic
- pipeline
- 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.)
- Withdrawn
Links
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- Rigid Pipes And Flexible Pipes (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、ガスパイプライン
等に使用される、高速延性破壊特性に優れたパイプライ
ン用耐震高強度鋼管に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earthquake-resistant high-strength steel pipe for use in gas pipelines and the like, which has excellent high-speed ductile fracture characteristics.
【０００２】[0002]
【従来の技術】高速延性破壊は不安定延性破壊とも呼ば
れ、鋼管の管軸方向に延性破壊が１００m/s 以上の高速
で長距離伝播する現象である。この高速延性破壊は、１
００ｍから数ｋｍにもおよぶ長距離破壊の可能性があ
り、それにより想定される被害の大きさから重要視され
ている。2. Description of the Related Art High-speed ductile fracture is also called unstable ductile fracture, which is a phenomenon in which ductile fracture propagates in the axial direction of a steel pipe at a high speed of 100 m / s or more over a long distance. This fast ductile fracture is 1
There is a possibility of long-distance destruction ranging from 00 m to several km, and is regarded as important because of the damage that can be expected.
【０００３】この高速延性破壊は、従来ＤＷＴＴ試験と
の相関が有るとされており、またＤＷＴＴ試験とシャル
ピー試験が相関を持つことから、鋼管のシャルピー吸収
エネルギーを確保することにより防止されてきた。しか
しながら、これらの防止基準は７０ksi（＝４９０N/mm
2 ）以下の強度レベルの鋼管で確立されたものであり、
近年開発されてきている８０ksi（＝５６０N/mm2 以上
の引張強度を持つ鋼板では、上記パラメーターでは不十
分であることが懸念されている。[0003] This high-speed ductile fracture has been conventionally correlated with the DWTT test, and since the DWTT test and the Charpy test have a correlation, they have been prevented by securing the Charpy absorbed energy of the steel pipe. However, these prevention criteria are 70 ksi (= 490 N / mm
2 ) Established with steel pipes of the following strength levels,
In the case of a steel plate having a tensile strength of 80 ksi (= 560 N / mm 2 or more) which has been developed in recent years, there is a concern that the above parameters are insufficient.
【０００４】一方、地震による液状化に際しては、地下
の埋設管には大きな塑性変形が生じることが懸念されて
いる。この液状化時の大変形では、局部座屈により変形
能が支配される。これに対し、局部座屈発生歪を向上さ
せる目的で、例えば、特開平９−２０２９２２号公報に
記載のような引張試験での応力−歪関係の最小勾配を規
定した鋼管製造法が開示されている。[0004] On the other hand, when liquefaction is caused by an earthquake, there is a concern that large plastic deformation may occur in an underground buried pipe. In this large deformation during liquefaction, the deformability is controlled by local buckling. On the other hand, for the purpose of improving local buckling generation strain, for example, a method for producing a steel pipe in which a minimum gradient of a stress-strain relationship in a tensile test is specified as disclosed in JP-A-9-202922 has been disclosed. I have.
【０００５】液状化時の最終状態としては、局部座屈波
形形成後さらに変形が進み、局部座屈域に生じる引張り
応力によりき裂を生じる、もしくは、座屈後の除荷によ
りき裂を生じるものである。このように、局部座屈発生
後も最終状態までには大きな変形能を有しているが、座
屈発生後の変形能力まで考慮しての必要特性は不明であ
った。[0005] As a final state at the time of liquefaction, after the local buckling waveform is formed, the deformation further proceeds, and a crack is generated by a tensile stress generated in the local buckling region, or a crack is generated by unloading after the buckling. Things. As described above, even after the occurrence of local buckling, it has a large deformability up to the final state, but the necessary characteristics in consideration of the deformability after the occurrence of buckling were unknown.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、高速延性破
壊による大事故を防止するための、高速延性破壊特性に
優れ、かつ、地震時に生ずる液状化現象での大変形でも
亀裂を生じない高速延性破壊特性に優れたパイプライン
用耐震高強度鋼管の提供を課題とする。DISCLOSURE OF THE INVENTION The present invention provides a high-speed ductile rupture characteristic for preventing a large accident due to a high-speed ductile rupture, and a high-speed high-speed ductile crushing method which does not crack even in a large deformation due to liquefaction caused by an earthquake. An object of the present invention is to provide an earthquake-resistant high-strength steel pipe for pipelines having excellent ductile fracture characteristics.
【０００７】[0007]
【課題を解決するための手段】発明者らは、高速延性破
壊の防止に、ＣＴＯＤ−Ｒカーブが大きく影響し、ＣＴ
ＯＤ−Ｒカーブより求められるδＲ−plateau によって
高速延性破壊特性を有効に規定できることを見いだし
た。すなわち、本発明は高速延性破壊特性に優れたパイ
プライン用耐震高強度鋼管とするためδＲ−plateau 、
降伏比ＹＲ、一様伸びＥｕを臨界的に限定するに至って
完成されたもので、その要旨とするところは、降伏比Ｙ
Ｒ：８８％以下、一様伸びＥｕ：８％以上であり、か
つ、δＲ−plateau ：２mm以上であることを特徴とす
る、高速延性破壊特性に優れたラインパイプ用耐震高強
度鋼管である。The present inventors have found that the CTOD-R curve greatly affects the prevention of high-speed ductile fracture,
It has been found that high-speed ductile fracture properties can be effectively defined by the δR-plateau determined from the OD-R curve. That is, the present invention provides a δR-plateau,
It has been completed by critically limiting the yield ratio YR and the uniform elongation Eu.
R: 88% or less, uniform elongation Eu: 8% or more, and δR-plateau: 2 mm or more, a seismic high-strength steel pipe for line pipes excellent in high-speed ductile fracture characteristics.
【０００８】[0008]
【発明の実施の形態】発明者らは、高速延性破壊の防止
に、ＣＴＯＤ−Ｒカーブが大きく影響することを見いだ
した。ＣＴＯＤ−Ｒカーブは図１に示すような試験片を
用い、途中除荷を繰り返すことによりき裂伝搬に対する
抵抗を測定するものである。この試験法により、各除荷
開始時のき裂長さと、そのときのき裂先端の開口変位量
（ＣＴＯＤ）の関係が図２のように求まるものである。
このうち、き裂伝播が大きい領域でのＣＴＯＤの飽和量
δＲ−plateau が鋼管における不安定延性破壊の伝播速
度と関係が大きいことを見いだした。BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have found that the CTOD-R curve has a great effect on the prevention of high-speed ductile fracture. The CTOD-R curve measures the resistance to crack propagation by repeating unloading using a test piece as shown in FIG. By this test method, the relationship between the crack length at the start of each unloading and the opening displacement (CTOD) of the crack tip at that time is determined as shown in FIG.
Among them, it was found that the saturation amount δR-plateau of CTOD in a region where crack propagation was large had a large relationship with the propagation speed of unstable ductile fracture in a steel pipe.
【０００９】図３にδＲ−plateau とバースト試験での
き裂速度の関係を示す。δＲ−plateau が２mm以上の領
域では、き裂速度が８０m/s 以下になっており、この速
度域では内圧の現象により高速延性破壊を防止可能であ
る。このように発明者らの見出した、この図３に示した
関係を用いることによって、バースト試験など実鋼管を
必要とする大掛かりな試験をすることなく、図１に示す
ような一般規格の試験片により、高速延性破壊特性を正
確に予測することが可能となった。FIG. 3 shows the relationship between the δR-plateau and the crack rate in the burst test. In the region where δR-plateau is 2 mm or more, the crack speed is 80 m / s or less. In this speed region, high-speed ductile fracture can be prevented by the phenomenon of internal pressure. By using the relationship shown in FIG. 3 found by the inventors in this way, the test piece of the general standard as shown in FIG. 1 can be used without performing a large-scale test such as a burst test that requires an actual steel pipe. As a result, it was possible to accurately predict high-speed ductile fracture characteristics.
【００１０】さらに、発明者らはδＲ−plateau を向上
させるためには降伏比ＹＲを規定することが有効である
ことを見出した。一方、液状化時の大変形特性に対して
は、特開平９−２０２９２２号公報に記載されている引
張試験での応力−歪曲線の最小勾配を規定した鋼管製造
法が開示されているが、液状化時の座屈発生ひずみは、
この最小勾配よりも、むしろ平均勾配と相関が大きいこ
とを、発明者らは見出した。さらに、座屈波形形成後の
き裂発生までの変形能は、座屈波長、引張試験での一様
伸びで支配されることを見いだした。座屈波長は鋼管の
管径管厚比（Ｄ／ｔ）で決まるため、座屈形成後の変形
能は、同じ管径管厚比で有れば、一様伸びＥｕが大きい
鋼管が優位となる。Furthermore, the inventors have found that it is effective to define the yield ratio YR in order to improve the δR-plateau. On the other hand, for a large deformation property at the time of liquefaction, a method for producing a steel pipe in which a minimum gradient of a stress-strain curve in a tensile test described in JP-A-9-202922 is specified is disclosed. Buckling strain during liquefaction is
The inventors have found that the correlation with the average slope is greater than the minimum slope. Furthermore, it was found that the deformability up to the crack initiation after the formation of the buckling waveform was governed by the buckling wavelength and the uniform elongation in the tensile test. Since the buckling wavelength is determined by the tube diameter ratio (D / t) of the steel tube, the deformability after the buckling is formed, if the tube diameter ratio is the same, a steel tube having a large uniform elongation Eu is superior. Become.
【００１１】以上の知見に基づき、８０ksi 以上の様々
な鋼種について、降伏比ＹＲ、一様伸びＥｕ、δＲ−pl
ateau を詳細に調査し、十分な高速延性破壊特性と耐震
性を兼ね備えるためには、降伏比ＹＲについては８８％
以下、一様伸びＥｕについては８％以上、δＲ−platea
u については２mm以上が、それぞれ臨界的な条件である
ことを見出し、これらの条件をすべて満足する高強度鋼
管を本発明の構成として限定するに至った。[0011] Based on the above findings, the yield ratio YR, uniform elongation Eu, δR-pl
Investigating ateau in detail, and in order to have sufficient high-speed ductile fracture characteristics and seismic resistance, the yield ratio YR was 88%.
Hereinafter, the uniform elongation Eu is 8% or more, and δR-platea
With respect to u, it was found that 2 mm or more was a critical condition, and high strength steel pipes satisfying all of these conditions were limited as the constitution of the present invention.
【００１２】なお、降伏比ＹＲについては８０％以上、
一様伸びＥｕについては１６％以下、δＲ−plateau に
ついては６mm以下が、高強度鋼管として製造可能な範囲
と考えられる。また、δＲ−plateau については、３mm
以上とすることによって不安定延性破壊することがほと
んどなくなり、理想的な高速延性破壊特性を得ることが
できる。The yield ratio YR is 80% or more.
The uniform elongation Eu of 16% or less and the δR-plateau of 6 mm or less are considered to be ranges that can be manufactured as a high-strength steel pipe. For δR-plateau, 3 mm
By doing so, unstable ductile fracture hardly occurs, and ideal high-speed ductile fracture characteristics can be obtained.
【００１３】[0013]
【実施例】強度レベル１００ksi（７００N/mm2 級）の
管径Ｄ＝７６２mm、管厚ｔ＝１７．５mmの鋼管につい
て、表１に示すＡ〜Ｆのサンプル材を用い、δＲ−plat
eau試験、バースト試験、直管曲げ試験を実施した。結
果を同じく表１に示す。EXAMPLE For a steel pipe having a strength level of 100 ksi (700 N / mm 2 class) with a pipe diameter D = 762 mm and a pipe thickness t = 17.5 mm, using the sample materials A to F shown in Table 1, δR-plat
The eau test, burst test, and straight pipe bending test were performed. The results are also shown in Table 1.
【００１４】[0014]
【表１】 [Table 1]
【００１５】本発明に属するサンプルＡ、Ｂ、Ｃは、い
ずれもδＲ−plateau は２mm以上であり、かつ、高速延
性亀裂の進展速度が５０m/s 以下であり、特にサンプル
ＡとＣでは不安定延性破壊は伝播していない。しかも、
いずれのサンプルも直管曲げ試験εmax も４５゜以上と
耐震性の指標となる変形能にも優れている。Samples A, B, and C belonging to the present invention all have a δR-plateau of 2 mm or more and a high-speed ductile crack growth speed of 50 m / s or less. Ductile fracture has not propagated. Moreover,
Each of the samples has a straight pipe bending test εmax of 45 ° or more and is excellent in deformability as an index of earthquake resistance.
【００１６】一方、比較例のサンプルＤとＦでは、１０
０m/s を超える高速延性亀裂が進展しており、また、サ
ンプルＥは高速延性亀裂が進展速度は７０m/s であるも
のの変形能がεmax ：３５゜と低く、いずれも耐震を考
慮したラインパイプ用途には適さないことが分かる。On the other hand, in the samples D and F of the comparative examples, 10
A high-speed ductile crack exceeding 0 m / s has developed. In Sample E, the high-speed ductile crack has a growth rate of 70 m / s, but has a low deformability of εmax: 35 °. It turns out that it is not suitable for use.
【００１７】[0017]
【発明の効果】以上のように、本発明によれば８０ksi
以上の高強度鋼管においても、地震時に懸念される高速
延性破壊特性を確実に予測したうえで、高速延性破壊特
性に優れたパイプライン用耐震高強度鋼管を提供でき
る。As described above, according to the present invention, 80 ksi
Even with the above high-strength steel pipes, it is possible to provide a seismic high-strength steel pipe for pipelines that is excellent in high-speed ductile fracture properties after reliably predicting high-speed ductile fracture properties that are concerned during an earthquake.
【図１】ＣＴＯＤ−Ｒカーブを求めるための試験片の形
状と３点曲げの荷重位置を示した図である。FIG. 1 is a diagram showing the shape of a test piece for obtaining a CTOD-R curve and the load positions of three-point bending.
【図２】ＣＴＯＤ−Ｒカーブ試験における、各除荷開始
時のき裂長さと、そのときのき裂先端の開口変位量（Ｃ
ＴＯＤ）の関係の一例を示した図である。FIG. 2 shows the crack length at the start of each unloading and the opening displacement (C) at the crack tip at the start of each unloading in the CTOD-R curve test.
FIG. 4 is a diagram showing an example of the relationship (TOD).
【図３】ＣＴＯＤ−Ｒカーブの開口変位量（ＣＴＯＤ）
の飽和量であるδＲ−plateauとバースト試験でのき裂
速度の関係の一例を示した図である。FIG. 3 CTOD-R curve opening displacement (CTOD)
FIG. 4 is a diagram showing an example of the relationship between the δR-plateau, which is the saturation amount, and the crack rate in a burst test.
Claims (1)
ｕ：８％以上であり、かつ、δＲ−plateau ：２mm以上
であることを特徴とする、高速延性破壊特性に優れたパ
イプライン用耐震高強度鋼管。1. Yield ratio YR: 88% or less, uniform elongation E
u: not less than 8% and δR-plateau: not less than 2 mm. An earthquake-resistant high-strength steel pipe for pipelines having excellent high-speed ductile fracture characteristics.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001046043A JP2002250480A (en) | 2001-02-22 | 2001-02-22 | Antiseismic high-strength steel pipe for a pipeline of superior high speed ductile fracture characteristics |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001046043A JP2002250480A (en) | 2001-02-22 | 2001-02-22 | Antiseismic high-strength steel pipe for a pipeline of superior high speed ductile fracture characteristics |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2002250480A true JP2002250480A (en) | 2002-09-06 |
Family
ID=18907740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2001046043A Withdrawn JP2002250480A (en) | 2001-02-22 | 2001-02-22 | Antiseismic high-strength steel pipe for a pipeline of superior high speed ductile fracture characteristics |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2002250480A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106018118A (en) * | 2016-05-18 | 2016-10-12 | 中国石油集团海洋工程有限公司 | Cooling box for CTOD (crank tip opening displacement) test and operating process of cooling box |
-
2001
- 2001-02-22 JP JP2001046043A patent/JP2002250480A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106018118A (en) * | 2016-05-18 | 2016-10-12 | 中国石油集团海洋工程有限公司 | Cooling box for CTOD (crank tip opening displacement) test and operating process of cooling box |
| CN106018118B (en) * | 2016-05-18 | 2019-08-23 | 中国石油集团海洋工程有限公司 | CTOD test cooler bin and its operating process |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20080513 |