JPH0653912B2 - High toughness ERW steel pipe with excellent reel barge layability - Google Patents
High toughness ERW steel pipe with excellent reel barge layabilityInfo
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- JPH0653912B2 JPH0653912B2 JP1307610A JP30761089A JPH0653912B2 JP H0653912 B2 JPH0653912 B2 JP H0653912B2 JP 1307610 A JP1307610 A JP 1307610A JP 30761089 A JP30761089 A JP 30761089A JP H0653912 B2 JPH0653912 B2 JP H0653912B2
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- layability
- electric resistance
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Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は、リールバージ敷設性に優れた高靭性電縫鋼管
に関するものである。TECHNICAL FIELD The present invention relates to a high toughness electric resistance welded steel pipe excellent in reel barge layability.
従来、海底ラインパイプの敷設方法としては、第２図に
示すように、バージ１上で手溶接、ＭＩＧ（Metal Iner
t Gas）溶接またはＭＡＧ（Metal Active Gas）溶接に
より円周溶接を行い、接続したパイプ２を送り出して海
底４に敷設する方法が最も一般的である。しかし、この
方法ではバージ１上にて溶接、溶接部の検査、コーティ
ング等を行う必要があり、作業スペースが狭いために作
業効率の点が劣ること、あるいは天候の影響を大きく受
けるために作業能率が悪いことなどの点より問題があっ
た。Conventionally, as a method of laying a submarine line pipe, as shown in FIG. 2, manual welding on a barge 1 or MIG (Metal Iner
The most common method is to perform circumferential welding by t gas) welding or MAG (Metal Active Gas) welding, send out the connected pipe 2 and lay it on the seabed 4. However, with this method, it is necessary to perform welding, inspection of the welded portion, coating, etc. on the barge 1, and the work space is small, so the work efficiency is inferior, or it is greatly affected by the weather and work efficiency is high. There was a problem in that it was bad.
このため、第３図（ａ）に示すように、陸上５で円周溶
接、検査、及びコーティング等を行い、できあがった長
尺のパイプ２を海上のバージ１のリール３上に巻き取
り、第３図（ｂ）に示すように目的とする海上におい
て、リール３からパイプ２を巻き戻しながら海底４に敷
設する、いわゆるリールバージ法が多用されつつある。For this reason, as shown in FIG. 3 (a), circumferential welding, inspection, coating, etc. are performed on the land 5, and the long pipe 2 thus completed is wound on the reel 3 of the barge 1 on the sea, As shown in FIG. 3 (b), the so-called reel barge method, in which the pipe 2 is unwound from the reel 3 and laid on the seabed 4 at the target sea, is being used frequently.
このリールバージ法では、非常に効率的に作業を行うこ
とができるものの、リール３に巻き取る時あるいは海底
に敷設するためにリール３から巻き戻す時に、パイプ２
の一部に引張及び圧縮の応力がかかり、第４図に示すよ
うにパイプ２の円周溶接７のトウ部に割れが生じやすい
という問題があった。Although the reel barge method can perform work very efficiently, the pipe 2 is not used when the reel 3 is wound up or unwound from the reel 3 to be laid on the seabed.
There is a problem that tensile and compressive stresses are applied to a part of the above, and as shown in FIG. 4, cracks are likely to occur in the toe part of the circumferential weld 7 of the pipe 2.
従来より、溶接部の靭性を改良する方法としては、特公
昭６０−３１８８８号あるいは特開昭５３−１２５７１
号がある。前者は、母材成分の炭素当量を規定しかつ溶
接後熱処理を行うものであり、後者は溶接時に被溶接材
料に超音波振動を付与して行うものである。これらは、
溶接部の靭性向上に効果はあるものの、前者では特に熱
処理工程の追加が必要である。後者は超音波を付与する
ための装置及び適当な振動数の調整が必要であり、また
振動数が不適当であると付与しないほうがかえって靭性
が優れるという問題がある。Conventionally, as a method for improving the toughness of a welded portion, Japanese Patent Publication No. Sho 61-31888 or Sho 53-12571.
There is an issue. The former defines the carbon equivalent of the base metal component and performs post-weld heat treatment, and the latter performs ultrasonic vibration to the material to be welded during welding. They are,
Although it is effective in improving the toughness of the welded portion, the former requires an additional heat treatment step. The latter requires a device for applying ultrasonic waves and adjustment of an appropriate frequency, and if the frequency is not appropriate, there is a problem that the toughness is better if not applied.
以上述べたように、リールバージ法により電縫鋼管を敷
設する場合、リールにパイプを巻き取る工程あるいは敷
設時にリールから巻き戻す工程があるため、パイプの一
部に引張及び圧縮の応力がかかり、円周溶接トウ部に割
れが生じやすいという問題点がある。As described above, when laying an electric resistance welded steel pipe by the reel barge method, since there is a step of winding the pipe on the reel or a step of rewinding from the reel at the time of laying, a tensile and compression stress is applied to a part of the pipe, There is a problem that cracks easily occur in the circumferential weld toe part.
本発明は、上記の事情にかんがみて開発されたもので、
リールバージ敷設性に優れた高靭性電縫鋼管を提供する
ものである。The present invention was developed in view of the above circumstances,
It is intended to provide a high toughness electric resistance welded steel pipe having excellent reel barge layability.
〔課題を解決するための手段〕 本発明者らは、電縫鋼管のリールバージ法への適用に当
り調査を重ねた結果、円周溶接トウ部の割れ発生には溶
接熱影響部の軟化が悪影響を及ぼしていることを見出
し、さらに研究を重ねたところ、溶接時の熱を受けても
軟化の程度が事実上問題のない高靭性電縫鋼管を用いる
ことにより、トウ部の割れを有効に防止し得ることを知
見し、本発明をなすに至ったのである。[Means for Solving the Problems] As a result of repeated investigations on the application of the electric resistance welded steel pipe to the reel barge method, the present inventors found that the weld heat affected zone was softened in the occurrence of cracks in the circumferential weld toe portion. We have found that it has an adverse effect, and conducted further research, and by using a high-toughness electric resistance welded steel pipe with virtually no problem in the degree of softening even when it receives heat during welding, it is possible to effectively crack the toe part. The inventors have found that they can be prevented and have completed the present invention.
すなわち、本発明は下記の技術手段から成る電縫鋼管で
ある。That is, the present invention is an electric resistance welded steel pipe including the following technical means.
成分として、 Ｃ：０．０３〜０．２０重量％、 Ｍｎ：０．５０〜１．５重量％、 Ｓｉ：０．０５〜０．５０重量％、 Ａｌ：０．００５〜０．０６０重量％ の範囲内で含有し、かつ、Ｎｂ、Ｖ、Ｔｉについて、 Ｎｂ＋Ｖ＋Ｔｉ≦０．０４０重量％ を満足し、残部は実質的に鉄及び不可避的不純物よりな
る鋼で、かつ炭素当量Ｃｅｑ及び溶接割れ感受性Ｐｃｍ
が、 ０．２０≦Ｃｅｑ≦０．３６ Ｐｃｍ≦０．２５ を満足し、さらに、降伏比（＝降伏応力／引張り強さ）
が８５％以下であることを特徴とする溶接軟化部の少な
いリールバージ敷設に優れた高靭性電縫鋼管である。As components, C: 0.03 to 0.20 wt%, Mn: 0.50 to 1.5 wt%, Si: 0.05 to 0.50 wt%, Al: 0.005 to 0.060 wt% Within the range of Nb, V, and Ti, satisfying Nb + V + Ti ≦ 0.040% by weight, the balance being steel essentially consisting of iron and inevitable impurities, and having a carbon equivalent Ceq and a weld cracking susceptibility. Pcm
Satisfies 0.20 ≦ Ceq ≦ 0.36 Pcm ≦ 0.25, and further, the yield ratio (= yield stress / tensile strength)
It is a high toughness electric resistance welded steel pipe excellent in reel barge laying with less weld softening part, characterized by being less than 85%.
但し、Ｃｅｑ及びＰｃｍは次式で与えられる。However, Ceq and Pcm are given by the following equations.
Ｃｅｑ＝Ｃ＋Ｍｎ／６＋Ｃｕ／１５ ＋Ｎｉ／１５＋Ｃｒ／５ ＋Ｍｏ／５＋Ｖ／５ Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０ ＋Ｃｕ／２０＋Ｎｉ／６０ ＋Ｃｒ／２０＋Ｍｏ／１５ ＋Ｖ／１０＋５Ｂ また、上記鋼に成分として （ａ）Ｎｉ：０．５０重量％以下、 Ｃｕ：０．５０重量％以下、 Ｃａ：０．００５重量％以下、 Ｃｒ：０．３重量％以下、 のうちから選ばれた１種もしくは２種以上または／およ
び （ｂ）Ｍｏ：０．３０重量％以下 Ｂ：０．００２重量％以下 のうち一種または二種 を含有させることによって、リールバージ敷設にさらに
優れた高靭性電縫鋼管を得ることができる。Ceq = C + Mn / 6 + Cu / 15 + Ni / 15 + Cr / 5 + Mo / 5 + V / 5 Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (a) Ni: 0 as a component in the steel. 50% by weight or less, Cu: 0.50% by weight or less, Ca: 0.005% by weight or less, Cr: 0.3% by weight or less, and one or more selected from or / and (b ) Mo: 0.30% by weight or less B: 0.002% by weight or less By incorporating one or two of them, it is possible to obtain a high toughness electric resistance welded steel pipe more excellent in reel barge laying.
以下に本発明の作用を説明する。 The operation of the present invention will be described below.
本発明者らは、上記した円周溶接トウ部の割れについ
て、ＡＰＩ１１０４に従って円周溶接部から試験片１０
を取り出し、第５図に示すように曲げ試験機１１を用い
て繰り返し曲げ試験（歪量５％）により再現試験を実施
し検討した結果、第４図に典型例にみられるように割れ
６が円周溶接７のトウ部より発生していることを確認す
ることができた。また、この割れは溶接熱影響部の軟化
の程度が大きい時に発生する傾向が大きく、溶接熱影響
部の軟化を小さくすれば有効に防止し得ることが明らか
となった。Regarding the cracks in the above-described circumferential welded toe portion, the present inventors have made a test piece 10 from the circumferential welded portion according to API 1104.
Then, as shown in FIG. 5, a bending tester 11 was used to conduct a repeated bending test (strain amount 5%) and a reproduction test was conducted. As a result, cracks 6 were found as shown in a typical example in FIG. It was possible to confirm that it was generated from the toe part of the circumferential weld 7. Further, it has been clarified that this crack tends to occur when the degree of softening of the weld heat affected zone is large, and can be effectively prevented by reducing the softening of the weld heat affected zone.
この種の割れは第６図のグラフに示した硬さＨｖの分布
の模式図から解るように、溶接部７による溶接熱影響部
８と母材９の硬度の不連続に起因するものであり、巻き
取り巻き戻し時に溶接熱影響部８と母材９で塑性変形の
不均一が生じるために発生すると考えられる。すなわ
ち、割れの発生は、軟化域をもつ溶接熱影響部８に変形
が集中し、局部的に加工硬化し脆化することにより起る
と考えられる。As can be seen from the schematic diagram of the distribution of hardness Hv shown in the graph of FIG. 6, this kind of crack is caused by the discontinuity in the hardness of the weld heat affected zone 8 and the base metal 9 due to the weld zone 7. It is considered that this occurs because nonuniform plastic deformation occurs in the weld heat affected zone 8 and the base material 9 during winding and rewinding. That is, the occurrence of cracks is considered to occur because the deformation is concentrated in the weld heat affected zone 8 having a softened region, and the work locally hardens due to work hardening.
また、第６図に示すように溶接熱影響部８が母材９に比
較して軟化する理由は、一般に電縫鋼管用鋼板は高強度
・高靭性を得るためにＣＲ（コントロールド・ローリン
グ）法が採用されているが、溶接時の熱によりＡC3点以
上に加熱され、ＣＲの効果がなくなるためと考えられ
る。特に、電縫鋼管では巻き取り巻き戻し時の応力状態
より見て、問題となるのはシーム溶接部よりも円周溶接
部における軟化である。Further, as shown in FIG. 6, the reason why the welding heat affected zone 8 is softened compared to the base material 9 is that the steel plate for ERW pipe is generally CR (controlled rolling) in order to obtain high strength and high toughness. Although the method is adopted, it is considered that the effect of CR is lost because the heat of welding heats it to the AC 3 point or higher. In particular, in the case of the electric resistance welded steel pipe, in view of the stress state at the time of winding and unwinding, what becomes a problem is softening at the circumferential weld portion rather than at the seam weld portion.
上記した検討結果より溶接熱影響部の軟化の程度を減少
させるために、種々の成分系について軟化の度合（△Ｈ
ｖ）を調査し、ある特定の成分系にすれば軟化の度合を
非常に小さく抑えることができることが発見し、本発明
に至った。From the above-mentioned examination results, in order to reduce the degree of softening of the weld heat affected zone, the degree of softening (ΔH
The present invention has been completed by investigating v) and found that the softening degree can be suppressed to a very small level by using a specific component system.
それは、第１図に示すように、Ｎｂ、Ｖ及びＴｉの合計
量とＣｅｑ（炭素当量）の値を規制することである。第
１図は、Ｎｂ＋Ｖ＋Ｔｉの量を０．０４０重量％以下及
び０．０４０重量％超にした場合の軟化の度合（△Ｈ
ｖ）とＣｅｑの関係を示したものであり、定性的に、Ｃ
ｅｑを増加させれば△Ｈｖを減ずることができることが
わかる。定量的には、Ｃｅｑを０．２０重量％以上にす
れば△Ｈｖを８以下に抑えることができる。△Ｈｖが８
以下では第５図に示した繰り返し曲げ試験より円周溶接
トウ部からの割れはほとんど皆無である。That is, as shown in FIG. 1, the total amount of Nb, V, and Ti and the value of Ceq (carbon equivalent) are regulated. FIG. 1 shows the degree of softening (ΔH) when the amount of Nb + V + Ti is 0.040% by weight or less and more than 0.040% by weight.
v) and Ceq, and qualitatively, C
It can be seen that ΔHv can be reduced by increasing eq. Quantitatively, ΔHv can be suppressed to 8 or less by setting Ceq to 0.20% by weight or more. △ Hv is 8
From the repeated bending test shown in FIG. 5, below, there is almost no crack from the circumferential welded toe part.
Ｎｂ、Ｖ及びＴｉの合計量の制限が軟化抑制に効果があ
るのは、これらは、単体あるいはそれらの複合により、
母材の強度を上げる、すなわちＣＲの効果を上げる元素
であり、これらの元素を限定することにより、ＣＲの効
果を減少することができるためと考えられる。さらに、
Ｃｅｑの上昇が軟化抑制に効果があるのは、基本的にＣ
Ｒの効果を減らすためと考えられ、円周溶接時の熱によ
る軟化の程度が少なくなり均一変形が行なわれ、曲げ延
性の改善には寄与すると考えられる。The limitation of the total amount of Nb, V, and Ti is effective in suppressing softening.
It is considered that this is an element that enhances the strength of the base material, that is, enhances the CR effect, and the CR effect can be reduced by limiting these elements. further,
Basically, the increase of Ceq is effective in suppressing softening
This is considered to reduce the effect of R, and it is considered that the degree of softening due to heat during circumferential welding is reduced and uniform deformation is performed, which contributes to the improvement of bending ductility.
Ｎｂ＋Ｖ＋Ｔｉを０．０４０重量％以下に規制するの
は、溶接熱影響部の軟化を、実際上問題のない程度まで
抑えるために、また降伏比を８５％以下にするために、
Ｎｂ＋Ｖ＋Ｔｉが０．０４０重量％以下であることが必
要である。よって、０．０４０重量％以下の範囲とし
た。また、Ｃｅｑの範囲については０．２０重量％未満
では、その効果がなく、０．３６重量％を越えると、Ｃ
ｅｑの上昇の効果が飽和するだけでなく、著しい靭性の
劣化が起る。よって、０．２０重量％以上０．３６重量
％以下の範囲とした。The Nb + V + Ti content is restricted to 0.040% by weight or less in order to suppress the softening of the weld heat affected zone to such an extent that there is practically no problem, and to set the yield ratio to 85% or less,
It is necessary that Nb + V + Ti is 0.040% by weight or less. Therefore, the range is 0.040% by weight or less. Regarding the range of Ceq, if it is less than 0.20% by weight, the effect is not exerted, and if it exceeds 0.36% by weight, C
Not only is the effect of increasing eq saturated, but significant deterioration of toughness occurs. Therefore, the range is set to 0.20% by weight or more and 0.36% by weight or less.
その他、本発明の鋼における各成分の限定理由について
説明する。In addition, the reasons for limiting each component in the steel of the present invention will be described.
Ｃは必要な強度を得るために、０．０３重量％以上の含
有が必須であるが、０．２０重量％を越えると、溶接割
れ感受性が増大するため０．０３〜０．２０重量％の範
囲とした。C is required to be contained in an amount of 0.03% by weight or more in order to obtain the required strength, but if it exceeds 0.20% by weight, the susceptibility to welding cracks increases, so 0.03 to 0.20% by weight is required. The range was set.
Ｓｉは脱酸剤としてまた強度を確保する目的で０．０５
重量％以上の添加が必要であるが、０．５０重量％を越
えると、低温靭性の劣化及び、溶接割れ感受性を高める
ので、０．０５〜０．５０重量％の範囲とした。Si is 0.05 as a deoxidizer and for the purpose of securing strength.
It is necessary to add more than 0.5% by weight, but if it exceeds 0.50% by weight, the low temperature toughness deteriorates and the weld cracking susceptibility increases, so the range was made 0.05 to 0.50% by weight.
Ｍｎは強度を確保するために、０．５０重量％以上の添
加が必要であるが、１．５重量％を越えると、溶接割れ
感受性が増大しラインパイプ敷設時に必要な曲げ延性の
劣化を招くため、０．５０〜１．５重量％の範囲とし
た。Mn needs to be added in an amount of 0.50% by weight or more in order to secure the strength, but if it exceeds 1.5% by weight, the susceptibility to welding cracks increases and the bending ductility required for laying a line pipe deteriorates. Therefore, the range is 0.50 to 1.5% by weight.
Ａｌは強力な脱酸元素であるが、０．００５重量％未満
ではその効果がなく、一方０．０６０重量％を越える
と、効果はほぼ飽和に達するだけでなく非金属介在物の
増加をもたらす。よって、０．００５〜０．０６０重量
％の範囲とした。Al is a strong deoxidizing element, but if it is less than 0.005% by weight, it has no effect. On the other hand, if it exceeds 0.060% by weight, the effect not only reaches almost saturation but also increases nonmetallic inclusions. . Therefore, the range is 0.005 to 0.060% by weight.
Ｎｉは強度及び耐ＨＩＣ性を向上させ、さらに母材及び
溶接熱影響部の靭性を著しく改善するため有効である
が、０．５０重量％を越えるとスケールきずの発生が著
しくなり、鋼板の表面性状を害するので、０．５０重量
％以下の範囲とした。Ni is effective because it improves strength and HIC resistance, and also significantly improves the toughness of the base metal and the weld heat affected zone. However, if it exceeds 0.50% by weight, scale flaws occur remarkably and the surface of the steel sheet Since it impairs the properties, the amount was made 0.50% by weight or less.
ＣｕはｐＨが高い環境下で鋼表面に安定な皮膜を生成し
て、耐蝕性を向上させると共に、耐ＨＩＣ性向上にも効
果を示す。しかしながら、Ｃｕ添加量が０．５０重量％
を越えれば熱間加工性を損なうので０．５０重量％以下
の範囲とした。Cu forms a stable film on the steel surface in an environment with a high pH, improves corrosion resistance, and is also effective in improving HIC resistance. However, the amount of Cu added is 0.50% by weight
If it exceeds the range, the hot workability is impaired, so the range was made 0.50% by weight or less.
Ｃａは硫化物系介在物の形状を球状化して、硫化物系介
在物がＨＩＣの起点となることを抑制し、これにより耐
ＨＩＣ性を確保するに有効な元素であるが、０．００５
重量％を越えるＣａの添加は大型介在物を増加させて耐
ＨＩＣ性及び耐水素ふくれ性を低下させるおそれがある
から、０．００５重量％以下の範囲とした。Ca is an element effective in making the shape of the sulfide-based inclusion spherical and suppressing the sulfide-based inclusion from becoming the starting point of HIC, thereby ensuring the HIC resistance.
Addition of Ca in excess of wt% may increase large inclusions and reduce HIC resistance and hydrogen blistering resistance, so the content was made 0.005 wt% or less.
Ｃｒは鋼の耐蝕性を向上させて鋼中への水素侵入を低下
させると共に、Ｎｉ添加に伴う耐ＳＳＣ性の劣化を防ぐ
効果がある。しかし、０．３０重量％を越えれば特に溶
接部の靭性が劣化するため、０．３０重量％以下の範囲
とした。Cr has the effects of improving the corrosion resistance of the steel, reducing the penetration of hydrogen into the steel, and preventing the deterioration of the SSC resistance due to the addition of Ni. However, when the content exceeds 0.30% by weight, the toughness of the welded portion is particularly deteriorated, so the range is set to 0.30% by weight or less.
Ｍｏ，Ｂ： Ｍｏ，Ｂはともに強度を高めるために添加する。しかし
Ｍｏは０．３０重量％を越えて添加しても効果が飽和し
経済的でなく、またＢは０．００２重量％を越えると靭
性が劣化するのでＭｏは０．３０％重量以下、Ｂは０．
００２重量％以下にそれぞれ限定する。Mo, B: Both Mo and B are added to increase the strength. However, if Mo is added in an amount exceeding 0.30% by weight, the effect is saturated and it is not economical, and if B exceeds 0.002% by weight, the toughness deteriorates. Is 0.
It is limited to 002% by weight or less.
Ｐｃｍは、溶接割れ感受性の指標であり、該成分系では
０．２５を越えると著しく溶接割れ感受性が高まり、円
周溶接部の曲げ延性が劣化する。Pcm is an index of susceptibility to welding cracks, and in the case of this component system, when it exceeds 0.25, susceptibility to welding cracks remarkably increases and bending ductility of the circumferential welded portion deteriorates.
よって、０．２５以下の範囲とした。Therefore, the range is set to 0.25 or less.
降伏比（降伏点／引張強さ）が８５％以下の規定は以下
の理由による。一般に、第７図に示す応力−歪曲線中の
曲線Ａで示す降伏比が高い材料は、応力がσ１を越える
と歪がε１を突破し、小さい応力で歪が著しく増加する
ことになる。特に円周溶接熱影響部に軟化部が生じ易い
材料（局部的に弱い部分をもつ材料）では、わずかな応
力の増加であっても歪が軟化部に集中し、トウ部に割れ
が発生し易く、最終的には第８図に示すように局部座屈
１３を起し易い傾向にある。しかし、第７図の曲線Ｂで
示す降伏比が低い材料では、第９図に示すパイプの中央
部に最大の曲げ応力がかかったとき、中央部が加工硬化
し、中央部から端の方向へ変形或が拡がるだけで均一変
形１４を起し、トウ部に割れは発生しにくく、さらに局
部座屈には至らない。このような数多くの実験事実よ
り、少なくとも降伏比が８５％以下であることが必要で
ある。The reason why the yield ratio (yield point / tensile strength) is 85% or less is as follows. Generally, in a material having a high yield ratio shown by a curve A in the stress-strain curve shown in FIG. 7, the strain exceeds ε 1 when the stress exceeds σ 1 , and the strain significantly increases with a small stress. . Especially in the case of a material where a softened portion is likely to occur in the circumferential weld heat affected zone (a material with a locally weak portion), the strain concentrates in the softened portion even with a slight increase in stress and cracks occur in the toe portion. It is easy to cause local buckling 13 as shown in FIG. 8 in the end. However, in the case of a material having a low yield ratio shown by the curve B in FIG. 7, when the maximum bending stress is applied to the central part of the pipe shown in FIG. 9, the central part is work hardened, and the direction from the central part to the end is increased. Even if it deforms or spreads, uniform deformation 14 occurs, cracks are less likely to occur in the toe portion, and further local buckling does not occur. From such a lot of experimental facts, it is necessary that the yield ratio is at least 85% or less.
この考え方でわかるように、母材と継手の強度の均一性
は非常に大事であり、円周溶接の熱で局部的に弱い部分
ができるということは絶対に避けなければならない。As can be seen from this way of thinking, the uniformity of the strength of the base material and the joint is very important, and it is absolutely necessary to avoid the formation of a locally weak portion due to the heat of circumferential welding.
電縫鋼管の製造工程の概略を第１０図によって説明す
る。An outline of the manufacturing process of the electric resistance welded steel pipe will be described with reference to FIG.
一般に電縫鋼管は、コイル状に巻かれた帯板をアンコイ
ラによって巻戻し、レベラで平坦化した後、帯板両サイ
ドをトリミング装置によって、所定の帯幅に加工すると
共に帯板継目エッジ部端面の仕上加工をするいわゆる前
処理を行う。Generally, in electric resistance welded steel pipe, a coiled strip is unwound by an uncoiler and flattened by a leveler, and then both sides of the strip are processed into a predetermined strip width by a trimming device and the end face of the strip seam edge part. A so-called pretreatment for finishing processing is performed.
さらにブレークダウンロールフォーミング方式では、第
１０図に示す如く、所要の幅にトリミングされた鋼帯２
０の両エッジ部２１を、先ずエッジフォーミングロール
３１によって所要の曲率に曲げ成形し、次いで数段のブ
レークダウンロール３２、及びサイドロール３３によっ
て、ほぼ断面円形の素管２２に成形し、成形された素管
２２の継目エッジ部２３の角度コントロール、仕上げ成
形、センタリングを数段のフインパスロール３４によっ
て行い、数段のフインパスロール３４の出側において、
図示してないコンタクトチップにより素管２２の継目エ
ッジ部２３を加熱し、加熱された素管２２の継目エッジ
部２３をスクイズロール３５により圧着接合するもので
ある。Further, in the breakdown roll forming method, as shown in FIG. 10, the steel strip 2 trimmed to a required width is used.
Both edge portions 21 of No. 0 are first bent and formed by the edge forming roll 31 to a required curvature, and then formed by the breakdown roll 32 and the side rolls 33 of several stages into the bare pipe 22 having a substantially circular cross section. The angle control, finish forming, and centering of the seam edge portion 23 of the raw pipe 22 are performed by the fin pass rolls 34 of several stages, and at the exit side of the fin pass rolls 34 of several stages,
The seam edge portion 23 of the raw pipe 22 is heated by a contact tip (not shown), and the heated seam edge portion 23 of the raw pipe 22 is pressure-bonded by a squeeze roll 35.
この圧着接合により生じた溶鋼ビートをスクイズロール
３５の後流側に設置したビード切削装置により切削除去
する一連の工程によって製造される。It is manufactured by a series of steps of cutting and removing the molten steel beat produced by this pressure bonding by a bead cutting device installed on the downstream side of the squeeze roll 35.
次に、本発明の実施例について説明する。 Next, examples of the present invention will be described.
第１表に示す組成のパイプ（外径２７３．１ｍｍ肉厚１
２．７ｍｍ）を素材に、被覆アーク溶接にてセルロース
系の溶接棒を用いて６層６パスで円周溶接を行い、ＡＰ
Ｉ１１０４に従って円周溶接部を含んで１２．７ｍｍ×
幅２５．４ｍｍ×長さ２３０ｍｍの試験片（ｎ＝１０
０）を採取し、第５図に示すように、歪量が５％の繰返
し曲げ試験を行い合計１０回曲げ後、溶接部近傍のわれ
発生の有無を調査した。結果を第２表に示した。Pipes with the composition shown in Table 1 (outer diameter 273.1 mm, wall thickness 1
(2.7 mm) as a raw material, and covered by arc welding using a cellulosic welding rod in 6 layers and 6 passes to obtain AP.
12.7 mm including circumferential welds according to I1104
Width 25.4 mm x length 230 mm test piece (n = 10
0) was sampled and, as shown in FIG. 5, a repeated bending test with a strain amount of 5% was performed, and after bending a total of 10 times, the occurrence of cracks near the weld was investigated. The results are shown in Table 2.
第１表において、本発明に基いた成分系Ｎo.８〜Ｎo.３
３は、ほとんど割れの発生が見られなかった。これに対
し、比較例Ｎo.１は、母材のＣ量及び溶接割れ感受性式
（Ｐｃｍ）の上限をはずれる場合であり、割れ発生率は
高い。比較例Ｎo.２は溶接割れ感受性式（Ｐｃｍ）の値
は０．０９９と小さいものの、炭素当量（Ｃｅｑ）の値
が下限をはずれ、溶接熱影響部の軟化部発生により３４
％の割れ発生率となっている。比較例Ｎo.３及びＮo.４
はそれぞれ、Ｃｅｑ及びＰｃｍが上限値を越えているた
め、高い発生率になっている。比較例Ｎo.５は、Ｐｃ
ｍ、Ｃｅｑ及び降伏比（ＹＲ）が規定値を満足している
ものの、Ｎｂ＋Ｖ＋Ｔｉの含有量が規定値を越えている
ため割れの発生率が高い。さらに比較例Ｎo.６及びＮo.
７では、ＹＲが上限をはずれるために極めて高い割れ発
生率である。In Table 1, the component systems No. 8 to No. 3 according to the present invention are shown.
In No. 3, almost no cracks were observed. On the other hand, Comparative Example No. 1 is a case where the C content of the base metal and the upper limit of the weld crack susceptibility formula (Pcm) deviate from each other, and the crack occurrence rate is high. In Comparative Example No. 2, although the value of the weld crack susceptibility formula (Pcm) is as small as 0.099, the value of carbon equivalent (Ceq) deviates from the lower limit, and the softening part of the weld heat affected zone causes 34
The crack occurrence rate is%. Comparative Examples No. 3 and No. 4
In each case, since Ceq and Pcm exceed the upper limit values, the occurrence rate is high. Comparative Example No. 5 is Pc
Although m, Ceq and the yield ratio (YR) satisfy the specified values, the crack occurrence rate is high because the content of Nb + V + Ti exceeds the specified values. Further, Comparative Examples No. 6 and No.
In No. 7, since the YR is out of the upper limit, the crack occurrence rate is extremely high.
すなわち、本発明の電縫鋼管を用いることにより、溶接
部の曲げ延性が改善され、リールバージ敷設用電縫鋼管
として極めて有効であることが実証された。That is, by using the electric resistance welded steel pipe of the present invention, the bending ductility of the welded portion was improved, and it was proved to be extremely effective as an electric resistance welded steel pipe for reel barge laying.
なお、電縫鋼管用鋼板の製造については、鋼片を１１８
０〜１２６０℃の温度に加熱し、その後の圧延にあたっ
て９６０℃以上で累積圧下率を５０％以上とし、仕上が
り温度を８００℃以下にした。For the production of the steel plate for ERW pipe,
It was heated to a temperature of 0 to 1260 ° C., and in the subsequent rolling, the cumulative rolling reduction was 50% or more at 960 ° C. or more, and the finishing temperature was 800 ° C. or less.
電縫鋼管は、ブレークダウンロールフォーミング方式に
よって製造した。製造装置は、ブレークダウンロール４
段、サイドロール３段、フィンパスロール３段、エッジ
フォーミングロール及びスクイズロールは共に１段であ
る。この装置を用いて鋼板を逐次円筒形状に成形し、外
径２７３．１ｍｍに仕上げた後、高周波溶接を行い、さ
らにポストアニーリングを施して所要の電縫鋼管を得
た。ERW steel pipe was manufactured by a breakdown roll forming method. The production equipment is a breakdown roll 4
The number of steps, the number of side rolls, the number of fin pass rolls, the number of edge forming rolls, and the number of squeeze rolls are all one. Using this apparatus, steel plates were sequentially formed into a cylindrical shape, finished to have an outer diameter of 273.1 mm, subjected to high frequency welding, and further subjected to post annealing to obtain a required electric resistance welded steel pipe.
〔発明の効果〕 以上説明したように、本発明の電縫鋼管は、すぐれた円
周溶接部の靭性を有し、リールバージ敷設用電縫鋼管と
して利用できるので、工業的に極めて利用価値の高いも
のである。 [Effects of the Invention] As described above, the electric resistance welded steel pipe of the present invention has excellent toughness of the circumferential welded portion and can be used as a reel barge laying electric resistance welded steel pipe, and thus has an extremely high industrial value. It is expensive.
第１図は軟化の度合い（△Ｈｖ）とＣｅｑの関係を示す
グラフ、第２図は一般的な海底ラインパイプの施工方法
の説明図、第３図はリールバージ法の説明図、第４図は
円周溶接トウ部に見られる典型的な割れを示す溶接部断
面図、第５図は繰返し曲げ試験方法の説明図、第６図は
ＣＲ材での硬さ分布を示す模式図、第７図は応力−歪曲
線、第８図は局部的に弱い部分をもち、かつ降伏比が高
いパイプの変形状態を示す斜視図、第９図は降伏比が低
いパイプの変形状態を示す斜視図、第１０図は電縫鋼管
の製造工程の平面図である。 １……バージ、２……電縫鋼管 ３……リール、４……海底 ５……陸上、６……割れ ７……溶接部、８……熱影響部 ９……母材、１０……試験片 １１……曲げ試験機、２０……鋼帯 ２１……エッジ部、２２……素管 ２３……継目エッジ部 ３１……エッジフォーミングロール ３２……ブレークダウンロール ３３……サイドロール ３４……フィンパスロール ３５……スクイズロールFIG. 1 is a graph showing the relationship between the degree of softening (ΔHv) and Ceq, FIG. 2 is an explanatory diagram of a general seabed line pipe construction method, FIG. 3 is an explanatory diagram of the reel barge method, and FIG. Is a cross-sectional view of a weld showing typical cracks found in a circumferential weld toe, FIG. 5 is an explanatory view of a repeated bending test method, FIG. 6 is a schematic view showing hardness distribution in a CR material, and FIG. The figure is a stress-strain curve, FIG. 8 is a perspective view showing a deformed state of a pipe having a locally weak portion, and a high yield ratio, and FIG. 9 is a perspective view showing a deformed state of a pipe having a low yield ratio. FIG. 10 is a plan view of a process for manufacturing an electric resistance welded steel pipe. 1 ... barge, 2 ... electric resistance welded steel pipe 3 ... reel, 4 ... sea bottom 5 ... land, 6 ... cracking 7 ... welded portion, 8 ... heat affected zone 9 ... base metal, 10 ... Test piece 11 …… Bending tester, 20 …… Steel strip 21 …… Edge part, 22 …… Element tube 23 …… Seam edge part 31 …… Edge forming roll 32 …… Breakdown roll 33 …… Side roll 34… … Fin pass roll 35 …… Squeeze roll
Claims (3)
り、かつ下記で与えられる炭素当量Ｃｅｑが０．２０以
上０．３６以下、及び溶接割れ感受性Ｐｃｍが０．２５
以下であることを特徴とする降伏比が８５％以下で、溶
接軟化部の少ない、リールバージ敷設性に優れた高靭性
電縫鋼管。 Ｃｅｑ＝Ｃ＋Ｍｎ／６＋Ｃｕ／１５ ＋Ｎｉ／１５＋Ｃｒ／５ ＋Ｍｏ／５＋Ｖ／５ Ｐｃｍ＝Ｃ＋Ｓｉ／３０＋Ｍｎ／２０ ＋Ｃｕ／２０＋Ｎｉ／６０ ＋Ｃｒ／２０＋Ｍｏ／１５ ＋Ｖ／１０＋５Ｂ1. C: 0.03 to 0.20% by weight, Mn: 0.50 to 1.5% by weight, Si: 0.05 to 0.50% by weight, Al: 0.005 to 0.060. The content of Nb, V, and Ti satisfies Nb + V + Ti ≦ 0.040% by weight, the balance is substantially iron and unavoidable impurities, and the carbon equivalent Ceq given below is 0. .20 or more and 0.36 or less, and weld crack susceptibility Pcm is 0.25
A high toughness electric resistance welded steel pipe having a yield ratio of 85% or less, a small weld softening portion, and excellent reel barge layability, which is characterized by being as follows. Ceq = C + Mn / 6 + Cu / 15 + Ni / 15 + Cr / 5 + Mo / 5 + V / 5 Pcm = C + Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B
求項１記載のリールバージ敷設性に優れた高靭性電縫鋼
管。2. In addition to the above components, Ni: 0.50 wt% or less, Cu: 0.50 wt% or less, Ca: 0.005 wt% or less, Cr: 0.3 wt% or less, A high toughness electric resistance welded steel pipe excellent in reel barge layability according to claim 1, containing one or more selected from the group consisting of:
ルバージ敷設性に優れた高靭性電縫鋼管。3. The reel barge layability according to claim 1 or 2, further comprising, in addition to the above components, one or two of Mo: 0.30% by weight or less and B: 0.002% by weight or less. Excellent toughness electric resistance welded steel pipe.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1307610A JPH0653912B2 (en) | 1989-09-08 | 1989-11-29 | High toughness ERW steel pipe with excellent reel barge layability |
| US07/546,243 US5134267A (en) | 1989-07-06 | 1990-06-29 | Method of conducting circumferential welding of electric welded steel line pipe to be laid by reel barge |
| DE69013591T DE69013591T2 (en) | 1989-07-06 | 1990-07-04 | Process for circumferential seam welding of electrically welded pipes for a pipeline to be laid by unwinding a reel on a work ship. |
| EP90307318A EP0407175B1 (en) | 1989-07-06 | 1990-07-04 | Method of conducting circumferential welding of electric welded steel line pipe to be laid by reel barge |
| NO903014A NO300719B1 (en) | 1989-07-06 | 1990-07-05 | Procedure for carrying out an external roundabout |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23173389 | 1989-09-08 | ||
| JP1-231733 | 1989-09-08 | ||
| JP1307610A JPH0653912B2 (en) | 1989-09-08 | 1989-11-29 | High toughness ERW steel pipe with excellent reel barge layability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH03211255A JPH03211255A (en) | 1991-09-17 |
| JPH0653912B2 true JPH0653912B2 (en) | 1994-07-20 |
Family
ID=26530056
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1307610A Expired - Fee Related JPH0653912B2 (en) | 1989-07-06 | 1989-11-29 | High toughness ERW steel pipe with excellent reel barge layability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0653912B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5353760B2 (en) * | 2010-02-26 | 2013-11-27 | Ｊｆｅスチール株式会社 | ERW steel pipe excellent in deformation characteristics and manufacturing method thereof |
| NO2692875T3 (en) | 2011-03-30 | 2018-05-12 | ||
| JP5293903B1 (en) | 2011-08-23 | 2013-09-18 | 新日鐵住金株式会社 | Thick ERW Steel Pipe and Method for Manufacturing the Same |
| CN104011245B (en) | 2011-12-27 | 2017-03-01 | 杰富意钢铁株式会社 | High-tension hot rolled steel plate and its manufacture method |
| BR112014018236B1 (en) | 2012-01-27 | 2019-04-02 | Nippon Steel & Sumitomo Metal Corporation | PIPES AND PRODUCTION METHODS OF THE SAME |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63227715A (en) * | 1987-03-17 | 1988-09-22 | Kawasaki Steel Corp | Production of hot-rolled steel sheet for line pipe having excellent low-temperature toughness, low yield ratio, and high tensile strength |
-
1989
- 1989-11-29 JP JP1307610A patent/JPH0653912B2/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63227715A (en) * | 1987-03-17 | 1988-09-22 | Kawasaki Steel Corp | Production of hot-rolled steel sheet for line pipe having excellent low-temperature toughness, low yield ratio, and high tensile strength |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH03211255A (en) | 1991-09-17 |
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