JP2003340518A - Manufacturing method of uoe steel pipe having good crush strength - Google Patents

Manufacturing method of uoe steel pipe having good crush strength

Info

Publication number
JP2003340518A
JP2003340518A JP2002150870A JP2002150870A JP2003340518A JP 2003340518 A JP2003340518 A JP 2003340518A JP 2002150870 A JP2002150870 A JP 2002150870A JP 2002150870 A JP2002150870 A JP 2002150870A JP 2003340518 A JP2003340518 A JP 2003340518A
Authority
JP
Japan
Prior art keywords
ratio
pipe
steel pipe
yield strength
uoe
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
JP2002150870A
Other languages
Japanese (ja)
Inventor
Eiji Tsuru
英司 津留
Hitoshi Asahi
均 朝日
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel Corp
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 Nippon Steel Corp filed Critical Nippon Steel Corp
Priority to JP2002150870A priority Critical patent/JP2003340518A/en
Priority claimed from PCT/JP2003/006486 external-priority patent/WO2003099482A1/en
Publication of JP2003340518A publication Critical patent/JP2003340518A/en
Pending legal-status Critical Current

Links

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a steel pipe for an UOE line pipe capable of improving compression strength in the process of external press load. <P>SOLUTION: In a manufacturing method of an UOE steel pipe, a steel plate is treated by C press, U press, and O press in order and the both edges of the steel plate are seam welded, and after that, the pipe is expanded. The steel pipe having good crush strength is characterized by ≥0.35 of the ratio α/β of the upset ratio in O press shown as α/the expanding ratio shown as β in the method. The expanding ratio may be 2% or more. <P>COPYRIGHT: (C)2004,JPO

Description

【発明の詳細な説明】Detailed Description of the Invention

【0001】[0001]

【発明の属する技術分野】本発明はラインパイプ等に使
用される鋼管をUOE製造法で成形する方法において、
圧潰特性を改善するための方法に関する。
TECHNICAL FIELD The present invention relates to a method for forming a steel pipe used for a line pipe or the like by a UOE manufacturing method,
A method for improving crush properties.

【0002】[0002]

【従来の技術】近年、原油・天然ガスの長距離輸送方法
としてラインパイプの重要性が高まっており、なかでも
海洋を渡る海底ラインパイプは3000mにおよぶ深度
にまで達してきた。一般にパイプラインの設計では、ま
ず鋼管内径が流体輸送量より決定され、続いて肉厚、材
質が、内圧負荷時の周方向応力を一定値に押さえるべく
亀裂伝播特性、腐食減量を考慮し、決定されている。し
かし、深海化に伴って水圧が高まり、従来はあまり重要
視されなかった圧潰強度が問題になりつつある。圧潰強
度は外径と肉厚の比に相関があり、鋼管の圧潰強度を高
めることによって大径化及び薄肉化が可能になる。従っ
て、圧潰強度が鋼管サイズを決定する主な設計因子とな
りはじめた。
2. Description of the Related Art In recent years, line pipes have become increasingly important as a long-distance transportation method for crude oil and natural gas, and in particular, submarine line pipes that cross the ocean have reached a depth of 3000 m. Generally, in the design of pipelines, the steel pipe inner diameter is first determined from the fluid transport amount, and then the wall thickness and material are determined by considering crack propagation characteristics and corrosion weight loss in order to keep the circumferential stress under internal pressure load to a constant value. Has been done. However, as the water pressure increases with the deepening of the sea, crushing strength, which has hitherto been less important, is becoming a problem. The crush strength has a correlation with the ratio of the outer diameter to the wall thickness, and by increasing the crush strength of the steel pipe, it is possible to increase the diameter and reduce the wall thickness. Therefore, the crush strength has begun to become the main design factor that determines the steel pipe size.

【0003】ところで、鋼管の圧潰強度は油井管におい
ては古くから研究されており、統計的にも数多くの実験
式が提案されてきた。その中で外径/肉厚比、降伏強
度、真円度、偏肉度、残留応力がその主な支配因子とさ
れた。これらの研究は材質が均質なシームレス鋼管につ
いて主に行われたものであるため、材料の異方性につい
ては多くを論じる必要はなかった。
By the way, the crushing strength of steel pipes has been studied for a long time in oil country tubular goods, and many empirical formulas have been statistically proposed. Outer diameter / thickness ratio, yield strength, roundness, uneven thickness, and residual stress were the main controlling factors. Since these studies were mainly conducted on seamless steel tubes of homogeneous material, it was not necessary to discuss much about material anisotropy.

【0004】しかし、長距離輸送に使用される幹線ライ
ンパイプでは大径であるため、UOE方式の製造法によ
る鋼管が使用される。UOE方式による鋼管の製造工程
は、図1に示すようにC成形(プレス)、U成形(プレ
ス)、O成形(プレス)、シーム溶接及び拡管する工程
からなる。さらに、O成形においては、図2に示すよう
にO金型によって縮径され、これはO成形のアプセット
と呼ばれる。また、拡管は、図3に示すように、金属セ
グメントで内側から押し拡げることにより真円度を矯正
する工程であり、周方向の引張応力が加えられて塑性変
形する。これらの曲げ、圧縮及び引張の、いずれの成形
も冷間で行われるため、最終製品、すなわち鋼管は、加
工硬化とバウシンガー効果の複合により機械的性質に異
方性を生じることになる。なお、バウシンガー効果とは
材料に塑性歪みを与えた後、それとは逆方向の降伏強度
が低下する現象である。従って、周方向に引張方向の塑
性歪みを与えたUOE鋼管は、周方向の圧縮降伏強度、
すなわち外圧負荷に対する降伏強度がバウシンガー効果
によって低下する。
However, since a main line pipe used for long-distance transportation has a large diameter, a steel pipe manufactured by the UOE method is used. As shown in FIG. 1, the manufacturing process of a steel pipe by the UOE method includes C forming (pressing), U forming (pressing), O forming (pressing), seam welding, and pipe expanding. Further, in O-molding, the diameter is reduced by an O-mold as shown in FIG. 2, which is called an O-molding upset. Further, as shown in FIG. 3, the pipe expansion is a process of correcting the circularity by pushing and expanding the metal segments from the inside, and is subjected to a tensile stress in the circumferential direction to be plastically deformed. Since all of these bending, compression and tension forming are performed cold, the final product, that is, the steel pipe, has anisotropic mechanical properties due to the combination of work hardening and the Bauschinger effect. The Bausinger effect is a phenomenon in which the yield strength in the opposite direction to that after the material is subjected to plastic strain is reduced. Therefore, the UOE steel pipe to which the plastic strain in the tensile direction in the circumferential direction is applied has the compressive yield strength in the circumferential direction,
That is, the yield strength against an external pressure load decreases due to the Bausinger effect.

【0005】一方、軸方向の荷重負荷に対しては成形時
の主歪みに荷重方向が直交するため、軸方向の引張及び
圧縮負荷ではその応力挙動に差を生じにくい。また、周
方向の荷重負荷が引張応力である場合、すなわち内圧負
荷に対しては全厚引張試験から得られる値を基準に強度
設計を行えば問題が生じることはない。
On the other hand, with respect to an axial load load, the main strain at the time of molding is orthogonal to the load direction. Therefore, stress behavior is unlikely to differ between axial tension and compression loads. Further, when the circumferential load is tensile stress, that is, when the internal pressure is applied, the strength design based on the value obtained from the full thickness tensile test does not cause any problem.

【0006】しかし、近年では深海用ラインパイプに適
用し得るUOE鋼管の需要が高まり、外圧による鋼管の
圧潰強度が問題になり始めた。圧潰は外圧により鋼管が
潰れる現象であり、座屈の一つであるため、圧縮の降伏
強度が圧潰強度を決定することとなる。従って、圧潰強
度が要求されるラインパイプにUOE鋼管を適用する際
には、バウシンガー効果による周方向の圧縮強度の低下
が問題になる。
However, in recent years, the demand for UOE steel pipes applicable to deep-sea line pipes has increased, and the crushing strength of steel pipes due to external pressure has become a problem. Crushing is a phenomenon in which a steel pipe is crushed by external pressure and is one of buckling, so the yield strength of compression determines the crushing strength. Therefore, when the UOE steel pipe is applied to a line pipe that requires crushing strength, there is a problem that the compressive strength in the circumferential direction decreases due to the Bausinger effect.

【0007】このような問題に対し、低下した圧縮降伏
強度を熱処理によって回復させる方法が、特開平9−3
545号公報及び特開平9−49025号公報に開示さ
れており、また、多くの研究論文に報告されている。こ
れらの方法では、成形により低下したUOE鋼管の圧縮
降伏強度は成形前の鋼板レベルにまで回復し、圧潰強度
はある程度改善される。
In order to solve such a problem, a method of recovering the lowered compressive yield strength by heat treatment is disclosed in JP-A-9-3.
It is disclosed in Japanese Patent Laid-Open No. 545 and Japanese Patent Laid-Open No. 9-49025 and is reported in many research papers. According to these methods, the compressive yield strength of the UOE steel pipe decreased by forming is restored to the steel plate level before forming, and the crushing strength is improved to some extent.

【0008】[0008]

【発明が解決しようとする課題】しかし、熱処理による
圧潰強度の改善では、加熱工程が追加させるため、著し
いコスト増加を招くことになる。本発明は熱処理を伴わ
なくともUOE製造工程を最適化することで鋼管の圧潰
強度を改善することを目的とする。
However, in the improvement of the crushing strength by the heat treatment, a heating step is added, which results in a significant increase in cost. An object of the present invention is to improve the crush strength of a steel pipe by optimizing the UOE manufacturing process without heat treatment.

【0009】[0009]

【課題を解決するための手段】本発明者らはUOE鋼管
の内表面から肉厚中心部(以下、内表面側)に圧縮塑性
歪みを与えることで圧潰強度が向上することに着目し、
O成形時のアプセット率と拡管時の拡管率の比を最適化
することによって、内表面側に圧縮塑性歪みを与え、圧
縮降伏応力の低下を最小限に留めることに成功した。一
方、拡管率が2%以上になると、O成形のアプセット率
に関わらず、拡管率とともに圧潰強度が向上することを
見出した。
Means for Solving the Problems The inventors of the present invention have noticed that crushing strength is improved by applying a compressive plastic strain from the inner surface of a UOE steel pipe to the wall thickness center portion (hereinafter, inner surface side),
By optimizing the ratio between the upset ratio during O-forming and the pipe expansion ratio during pipe expansion, we succeeded in imparting compressive plastic strain to the inner surface side and minimizing the decrease in compressive yield stress. On the other hand, it has been found that when the pipe expansion ratio is 2% or more, the crush strength is improved together with the pipe expansion ratio regardless of the upset ratio of O molding.

【0010】すなわち、本発明の要旨とするところは、
以下の通りである。 (1)鋼板を順にC成形、U成形、O成形し、鋼板の端
部同士をシーム溶接後、拡管するUOE鋼管の製造方法
において、O成形時のアプセット率αと拡管時の拡管率
βの比を α/β≧0.35 とすることを特徴とする圧潰強度に優れたUOE鋼管の
製造方法。 (2)鋼板を順にC成形、U成形、O成形し、鋼板の端
部同士をシーム溶接後、拡管するUOE鋼管の製造方法
において、拡管時の拡管率を2%以上とすることを特徴
とする圧潰強度に優れたUOE鋼管の製造方法である。
That is, the gist of the present invention is that
It is as follows. (1) In a method for manufacturing a UOE steel pipe in which steel sheets are sequentially C-formed, U-formed, and O-formed, and the ends of the steel sheets are seam-welded and then expanded, the upset ratio α during O-forming and the pipe expansion ratio β during expansion are A method of manufacturing a UOE steel pipe having excellent crush strength, characterized in that the ratio is α / β ≧ 0.35. (2) In a method of manufacturing a UOE steel pipe in which steel sheets are sequentially C-formed, U-formed, and O-formed, and the ends of the steel sheets are seam-welded and then expanded, the pipe expansion ratio during pipe expansion is set to 2% or more. It is a method of manufacturing a UOE steel pipe having excellent crushing strength.

【0011】[0011]

【発明の実施の形態】本発明者らはUOE方式で製造し
た鋼管の断面において、鋼板の外表面から肉厚中心部
(以下、外表面側)の周方向の圧縮降伏強度を、周方向
における採取位置を変化させて詳細に調査した。試験片
は直径6mm、長さ15mmの円柱で、周方向を長手と
した。その結果を図4に示すが、横軸は、鋼管のシーム
溶接部の軸対称部を0゜とする反時計回りの角度であ
り、シーム溶接部は180゜である。縦軸の圧縮降伏強
度維持率は、鋼管の圧縮降伏強度を成形前の鋼板の圧縮
強度で除した値の百分率である。このように鋼管の外表
面側の圧縮降伏強度は、鋼板の圧縮降伏強度の80〜9
0%に低下していることがわかった。そこで図1に示し
たC成形、U成形、O成形、拡管の各工程での歪み挙動
を解析した結果、外表面側では、U成形で最も大きな引
張塑性歪みが生じ、O成形のアプセット時には圧縮降伏
強度をわずかに超える圧縮応力による圧縮塑性歪みが生
じ、拡管時には再び引張降伏強度を超える引張応力によ
る引張塑性歪みが生じることがわかった。
BEST MODE FOR CARRYING OUT THE INVENTION In the cross section of a steel pipe manufactured by the UOE method, the inventors have shown that the compressive yield strength in the circumferential direction from the outer surface of a steel sheet to the center of wall thickness (hereinafter, outer surface side) is measured in the circumferential direction. Detailed sampling was performed by changing the sampling position. The test piece was a cylinder having a diameter of 6 mm and a length of 15 mm, and the longitudinal direction was the circumferential direction. The results are shown in FIG. 4, where the horizontal axis is the counterclockwise angle with the axially symmetrical portion of the seam welded portion of the steel pipe being 0 °, and the seam welded portion is 180 °. The compressive yield strength retention rate on the vertical axis is the percentage of the value obtained by dividing the compressive yield strength of the steel pipe by the compressive strength of the steel sheet before forming. As described above, the compressive yield strength of the outer surface side of the steel pipe is 80 to 9 of the compressive yield strength of the steel sheet.
It was found to have dropped to 0%. Therefore, as a result of analyzing the strain behavior in each process of C forming, U forming, O forming, and pipe expanding shown in FIG. 1, the largest tensile plastic strain occurs in U forming on the outer surface side, and compression occurs during upsetting of O forming. It was found that compressive plastic strain due to compressive stress slightly exceeding the yield strength occurs, and tensile plastic strain due to tensile stress exceeding tensile yield strength again occurs during pipe expansion.

【0012】そこでO成形のアプセット時の圧縮塑性歪
みと拡管時の引張塑性歪みのバランスを制御すること
で、外表面側の圧縮降伏応力の低下を抑制し得る可能性
に着目した。バウシンガー効果は塑性歪みとは逆方向の
降伏強度が低下する現象であることから、アプセット率
を大きくして圧縮塑性歪みをより多く加え、拡管率を小
さくして引張予歪みを少なくすることにより、外表面側
における圧縮降伏応力の低下の抑制を図った。
Therefore, attention has been paid to the possibility of suppressing the decrease in the compressive yield stress on the outer surface side by controlling the balance between the compressive plastic strain at the time of upsetting in O-forming and the tensile plastic strain at the time of pipe expansion. The Bauschinger effect is a phenomenon in which the yield strength decreases in the direction opposite to the plastic strain, so by increasing the upset ratio to add more compressive plastic strain and decreasing the pipe expansion ratio to reduce the tensile prestrain. , The reduction of the compressive yield stress on the outer surface side was suppressed.

【0013】試験は外径/肉厚が18.7の鋼管をO成
形のアプセット率αと拡管率βの比を変化させて製造
し、溶接部と軸対称部の外表面より1/4全厚部を中心
に圧縮試験片を採取して行った。結果をα/βに対する
圧縮降伏強度維持率の変化として図5に示す。ここでア
プセット率と拡管率はそれぞれ、次の定義による。
In the test, a steel pipe having an outer diameter / thickness of 18.7 was manufactured by changing the ratio of the upset ratio α and the pipe expansion ratio β of O forming, and a ¼ total area was formed from the outer surface of the welded portion and the axisymmetric portion. A compression test piece was collected centering on the thick part. The results are shown in FIG. 5 as changes in the compressive yield strength retention rate with respect to α / β. Here, the upset ratio and the pipe expansion ratio are defined as follows.

【0014】これよりα/β≧0.35とすることで圧
縮降伏強度維持率が90%に達することを明らかにし、
α/βの下限を0.35とした。α/βの上限は、後述
するαの上限とβの下限の好ましい範囲及び最適な範囲
に依存し、好ましい範囲は1以下であり、最適な範囲は
0.6以下である。αの下限は図6及び7に示したよう
な溶接前のシームギャップの最小化及び溶接部ピーキン
グ低減から0.3%以上であることが望ましい。αの上
限については、大きくなるほど圧縮降伏強度の低減を妨
げることができるが、O成形時に図8に示すような開先
部のオーバーラップ又はバックリングが発生し易くなる
ため、外径/肉厚との関係にもよるが、0.5%以下に
することが好ましい。なお、開先部のオーバーラップ及
びバックリングを防止するには図9に示すようなO成形
の金型内面のシーム溶接部に相当する部位に軸中心に向
けて拡がるテーパーを有した突起形状を設けることが有
効である。
From this, it is clarified that the compression yield strength retention rate reaches 90% by setting α / β ≧ 0.35,
The lower limit of α / β was set to 0.35. The upper limit of α / β depends on the preferable range and the optimum range of the upper limit of α and the lower limit of β described later, and the preferable range is 1 or less, and the optimum range is 0.6 or less. The lower limit of α is preferably 0.3% or more from the viewpoint of minimizing the seam gap before welding and reducing the peaking of the welded portion as shown in FIGS. 6 and 7. Regarding the upper limit of α, the larger the value, the more the hindering the reduction of the compression yield strength, but the overlap or buckling of the groove portion as shown in FIG. However, it is preferably 0.5% or less. In order to prevent overlap and buckling of the groove portion, a protrusion shape having a taper that expands toward the axial center is formed at a portion corresponding to the seam weld portion on the inner surface of the O-molding die as shown in FIG. It is effective to provide them.

【0015】発明者らは、さらに圧縮降伏強度維持率に
及ぼす拡管率の影響について検討を行った。その結果を
図10に示すが、拡管率が2%を超えると圧縮降伏強度
維持率は80%を安定的に超え、拡管率とともに増加す
ることがわかる。従って、厚肉材でO成形成形機のプレ
ス能力不足等の理由により、アプセット率が十分に取れ
ない場合でも拡管率を2%以上とすることで圧縮降伏強
度維持率を85%以上にすることができることがわかっ
た。拡管率を増加させると、圧縮降伏強度維持率は向上
するが、より多くの塑性歪みを与えることになるため降
伏比の増加、一様伸びの低下、衝撃値の低下などが現れ
る。これらの機械的性質の劣化から最大拡管率は5%以
下とすることが好ましい。また、拡管率を低下させると
真円度が確保できなくなるため、0.5%以上とするこ
とが好ましく、最適な範囲は0.6%以上である。な
お、バウシンガー効果による外面側の圧縮降伏強度低下
率は拡管時の引張塑性歪みの大きさ及び肉厚によって変
化する造管時の曲げ加工による引張塑性歪みには大きく
依存しない。一方、内面側の圧縮降伏強度の上昇は、O
プレス時の圧縮歪みの大きさ及び肉厚によって変化する
加工硬化の度合いに依存する。従って、肉厚が厚くなる
と外面側の圧縮降伏強度は変化せず、内面側の圧縮降伏
強度が大きくなる。本発明の効果は、少なくとも肉厚、
20〜42mmの範囲についてはその効果が確認され
た。
The inventors further examined the influence of the pipe expansion ratio on the compression yield strength retention ratio. The results are shown in FIG. 10, and it can be seen that when the expansion ratio exceeds 2%, the compression yield strength maintenance ratio stably exceeds 80%, and increases with the expansion ratio. Therefore, even if the upset ratio cannot be sufficiently obtained due to insufficient press capacity of the O-molding machine for thick-walled materials, the pipe expansion ratio should be set to 2% or more to maintain the compression yield strength maintenance ratio to 85% or more. I found that When the expansion ratio is increased, the compressive yield strength retention ratio is improved, but since more plastic strain is given, the yield ratio increases, the uniform elongation decreases, and the impact value decreases. The maximum tube expansion ratio is preferably 5% or less due to deterioration of these mechanical properties. Further, if the pipe expansion ratio is reduced, the circularity cannot be ensured, so 0.5% or more is preferable, and the optimum range is 0.6% or more. The rate of decrease in the compressive yield strength on the outer surface side due to the Bauschinger effect does not largely depend on the magnitude of tensile plastic strain during pipe expansion and the tensile plastic strain due to bending during pipe forming, which changes depending on the wall thickness. On the other hand, the increase in compressive yield strength on the inner surface side is
It depends on the degree of work hardening which varies depending on the magnitude and thickness of compressive strain during pressing. Therefore, as the wall thickness increases, the compressive yield strength on the outer surface side does not change and the compressive yield strength on the inner surface side increases. The effect of the present invention is at least the thickness,
The effect was confirmed in the range of 20 to 42 mm.

【0016】[0016]

【実施例】材質がX−65及びX80であり、外径及び
肉厚が、それぞれ660〜711mm及び25〜38m
mの範囲であるUOE鋼管を、表1に示した外径/肉厚
比、アプセット率及び拡管率で製造した。この鋼管から
直径6mm、長さ15mmの円柱で、周方向を長手とし
た圧縮試験片を切り出して圧縮降伏強度を測定し、圧縮
降伏強度維持率として示した。また一部の鋼管では長さ
5mの鋼管を圧潰試験体とし、圧力容器内に設置して鋼
管に軸力が発生しないように水圧を負荷する単軸圧潰試
験を行い、圧潰強度を測定した。結果を表1に示す。
[Example] The materials are X-65 and X80, and the outer diameter and the wall thickness are 660 to 711 mm and 25 to 38 m, respectively.
UOE steel pipes in the range of m were manufactured with the outer diameter / wall thickness ratio, upset ratio and pipe expansion ratio shown in Table 1. From this steel pipe, a compression test piece having a diameter of 6 mm and a length of 15 mm and having a longitudinal direction in the circumferential direction was cut out, and the compression yield strength was measured and shown as the compression yield strength retention rate. Further, for some of the steel pipes, a steel pipe having a length of 5 m was used as a crushing test body, and a uniaxial crushing test in which water pressure was applied so as to prevent axial force from being generated in the steel pipe was set in a pressure vessel to measure the crushing strength. The results are shown in Table 1.

【0017】製造No.1〜4は、アプセット率と拡管
率の比が本発明の範囲内にあり、材質及び外径/肉厚比
が同一でα/β比が0.35に満たない製造No.14
〜17よりも圧縮降伏強度維持率が大きい。また、製造
No.1、2及び14の鋼管に対して圧潰試験を行った
ところ、本発明の範囲内である製造No.1及び2の圧
潰強度は本発明の範囲外の製造No.14よりも高く、
本発明の効果が実証できた。また、製造No.5は、材
質及び外径/肉厚比が同一でα/β比が0.35に満た
ない製造No.18よりも板材降伏強度に対する鋼管圧
縮降伏強度比が大きい。
Manufacturing No. Production Nos. 1 to 4 have the upset ratio and the pipe expansion ratio within the scope of the present invention, have the same material and outer diameter / wall thickness ratio, and have an α / β ratio of less than 0.35. 14
The retention rate of compressive yield strength is larger than -17. In addition, the manufacturing number. When a crushing test was performed on the steel pipes Nos. 1, 2 and 14, the production No. within the scope of the present invention. The crushing strengths of Nos. 1 and 2 are manufacturing numbers outside the range of the present invention. Higher than 14,
The effect of the present invention was verified. In addition, the manufacturing number. Production No. 5 has the same material and outer diameter / thickness ratio, and the α / β ratio is less than 0.35. The steel pipe compressive yield strength ratio to the plate yield strength is larger than that of No. 18.

【0018】製造No.6〜12は拡管率を2%以上と
したもので、α/β比に依らず、板材降伏強度に対する
鋼管圧縮降伏強度比が、材質及び外径/肉厚比が同一で
拡管率が2%未満の製造No.14〜17よりも良好で
ある。このうち、製造No.6について圧潰試験を行っ
たところ、製造No.14よりも高い圧潰強度を有する
ことが明らかになった。
Manufacturing No. Nos. 6 to 12 have a pipe expansion ratio of 2% or more, and regardless of the α / β ratio, the steel pipe compression yield strength ratio to the plate yield strength is the same as the material and the outer diameter / wall thickness ratio, and the pipe expansion ratio is 2%. Manufacturing No. less than Better than 14-17. Of these, manufacturing number. When a crushing test was performed on No. 6, the production No. It was found to have a crush strength higher than 14.

【0019】製造No.13は拡管率を4%として製造
したもので、同サイズ、同鋼種の製造No.18に比べ
て圧縮降伏強度の低下が小さかった。
Manufacturing No. No. 13 was manufactured with a pipe expansion ratio of 4%. Manufacturing No. 13 of the same size and steel type. Compared with No. 18, the decrease in compressive yield strength was small.

【0020】[0020]

【表1】 [Table 1]

【0021】[0021]

【発明の効果】以上述べたように本発明によれば、UO
E方式で製造した鋼管のO成形時のアプセット率と拡管
時の拡管率の比を特定すること、及び拡管率を2%以上
とすることでより高い圧潰抵抗を付与することが可能で
あり、圧潰強度に優れたUOE鋼管を低コストで提供で
きる、これは、深海のような高い圧潰強度が要求される
環境においても、天然ガス、原油等の輸送用ラインパイ
プ等に使用することができ、産業上、極めて貢献度が高
いものである。
As described above, according to the present invention, the UO
It is possible to give a higher crush resistance by specifying the ratio of the upset ratio at the time of O molding of the steel pipe manufactured by the E method and the pipe expansion ratio at the time of pipe expansion, and by setting the pipe expansion ratio to 2% or more, It is possible to provide UOE steel pipes with excellent crushing strength at low cost. This can be used for line pipes for transportation of natural gas, crude oil, etc. even in an environment where high crushing strength is required such as deep sea. It has a very high contribution to the industry.

【図面の簡単な説明】[Brief description of drawings]

【図1】UOE方式による鋼管製造プロセスの模式図。FIG. 1 is a schematic view of a UOE method for manufacturing a steel pipe.

【図2】O成形の模式図。FIG. 2 is a schematic diagram of O molding.

【図3】拡管成形の模式図。FIG. 3 is a schematic view of tube expansion molding.

【図4】UOE鋼管の圧縮降伏強度維持率の分布。FIG. 4 is a distribution of the compressive yield strength retention rate of UOE steel pipes.

【図5】アプセット率/拡管率比による圧縮降伏強度維
持率の変化。
FIG. 5 shows changes in compressive yield strength retention rate depending on the upset ratio / tube expansion ratio.

【図6】溶接部シームギャップの模式図。FIG. 6 is a schematic diagram of a weld seam gap.

【図7】溶接部ピーキングの模式図。FIG. 7 is a schematic diagram of welded peaking.

【図8】開先部のオーバーラップ及びバックリングの模
式図。
FIG. 8 is a schematic diagram of overlap and buckling of the groove portion.

【図9】O成形金型突起形状の例。FIG. 9 shows an example of the O-molding die projection shape.

【図10】拡管率による圧縮降伏強度維持率の変化。FIG. 10 shows changes in the compressive yield strength retention rate depending on the pipe expansion rate.

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 鋼板を順にC成形、U成形、O成形し、
鋼板の端部同士をシーム溶接後、拡管するUOE鋼管の
製造方法において、O成形時のアプセット率αと拡管時
の拡管率βの比を α/β≧0.35 とすることを特徴とする圧潰強度に優れたUOE鋼管の
製造方法。
1. A steel sheet is sequentially C-formed, U-formed, and O-formed,
A method of manufacturing a UOE steel pipe in which ends of a steel sheet are seam-welded and then expanded, wherein a ratio of an upset ratio α during O forming and a pipe expansion ratio β during expansion is α / β ≧ 0.35. A method for manufacturing a UOE steel pipe having excellent crush strength.
【請求項2】 鋼板を順にC成形、U成形、O成形し、
鋼板の端部同士をシーム溶接後、拡管するUOE鋼管の
製造方法において、拡管時の拡管率を2%以上とするこ
とを特徴とする圧潰強度に優れたUOE鋼管の製造方
法。
2. A steel sheet is sequentially C-formed, U-formed, and O-formed,
A method for producing a UOE steel pipe having excellent crushing strength, which is characterized in that a pipe expansion ratio during pipe expansion is 2% or more in a process for producing a UOE steel pipe in which pipe ends are seam-welded and then expanded.
JP2002150870A 2002-05-24 2002-05-24 Manufacturing method of uoe steel pipe having good crush strength Pending JP2003340518A (en)

Priority Applications (1)

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Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP2002150870A JP2003340518A (en) 2002-05-24 2002-05-24 Manufacturing method of uoe steel pipe having good crush strength
PCT/JP2003/006486 WO2003099482A1 (en) 2002-05-24 2003-05-23 Uoe steel pipe with excellent crash resistance, and method of manufacturing the uoe steel pipe
EP03733045A EP1541252B1 (en) 2002-05-24 2003-05-23 Uoe steel pipe with excellent crash resistance, and method of manufacturing the uoe steel pipe
US10/515,543 US7892368B2 (en) 2002-05-24 2003-05-23 UOE steel pipe excellent in collapse strength and method of production thereof
US12/462,218 US7967926B2 (en) 2002-05-24 2009-07-30 UOE steel pipe excellent in collapse strength and method of production thereof

Publications (1)

Publication Number Publication Date
JP2003340518A true JP2003340518A (en) 2003-12-02

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ID=29768612

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Country Link
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