JP2004017134A - Method for manufacturing spiral welded steel pipe - Google Patents

Method for manufacturing spiral welded steel pipe Download PDF

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Publication number
JP2004017134A
JP2004017134A JP2002179408A JP2002179408A JP2004017134A JP 2004017134 A JP2004017134 A JP 2004017134A JP 2002179408 A JP2002179408 A JP 2002179408A JP 2002179408 A JP2002179408 A JP 2002179408A JP 2004017134 A JP2004017134 A JP 2004017134A
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Japan
Prior art keywords
welding
steel strip
steel pipe
submerged arc
spiral
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.)
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JP2002179408A
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Japanese (ja)
Inventor
Yutaka Kano
鹿野　裕
Hiroshi Samoto
佐本　博司
Daisuke Koseki
小関　大祐
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
Nippon Steel Spiral Pipe Co Ltd
Original Assignee
Sumitomo Metal Industries Ltd
Sumikin Spiral Pipe Co Ltd
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Priority to JP2002179408A priority Critical patent/JP2004017134A/en
Publication of JP2004017134A publication Critical patent/JP2004017134A/en
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a spiral welded steel pipe which does not increase an oxygen quantitiy at a weld zone even in the case of high-speed welding, can prevent the overlap of the weld zone from occurring and also can prevent the deterioration of the impact strength of the weld zone. <P>SOLUTION: The spiral welded steel pipe is manufactured by welding both crosswise edges of a steel strip 1 in the submerged arc welding method while the steel strip (hot rolled coil) 1 with mill scale on the surface is formed into a spiral. High-speed welding is performed after the mill scale on both edges of the steel strip 1 is removed. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、スパイラル溶接鋼管の製造方法に関する。
【０００２】
【従来の技術】
従来から、熱延コイルを螺旋状に成形しながら、合わせ部分となる端部同士をサブマージアーク溶接法により溶接して、スパイラル溶接鋼管を製造することが行われている。
このサブマージアーク溶接によるスパイラル溶接鋼管の製造において、生産性を高めるために溶接速度を速くすると、溶接部への入熱が不足して溶け込み不足が発生するので、これに対処するために、電流値を高くすることや、あるいは電極数を増やすことが一般に行われている。
【０００３】
【発明が解決しようとする課題】
しかしながら、このような方法では、入熱不足を解消することはできても、溶接速度が速くなることにより、溶接金属中の酸素量が増加して、オーバーラップと呼ばれる欠陥を生じたり、衝撃性能が低下するという問題がある。
【０００４】
すなわち、熱延コイル表面に生成しているミルスケール（酸化鉄）が溶接時の熱で熱分解して酸素を発生し、その酸素が溶接金属中に溶解する。その溶解した酸素は、溶接速度がさほど速くないときには、フラックスによる脱酸反応に十分な時間を取ることができ、脱酸されるので問題とならないが、溶接速度が速くなると、フラックスによる脱酸反応に必要な時間が不十分になって脱酸されにくくなり、酸素量が増加する。
図２は、「溶鉄・溶宰の物性値便覧」（日本鉄鋼協会発行）に示された図である。酸素量の異なる溶融金属を毛細管に入れて落下させるための引力について、横軸を酸素量Ｏ（ｗｔ％）、縦軸を表面張力γ（ｄｙｎｅ／ｃｍ）としてまとめられた図であり、溶鉄が１５７０℃の場合（図中▲１▼）と１５５０℃の場合について２例（図中▲２▼と▲３▼）が示されている。酸素量が多くなると、表面張力が低下することが分る。
表面張力が低下すると、溶接ビートの両端部に図３に示すようなオーバーラップが発生するとともに、溶接部の衝撃性能が低下するという問題がある。
【０００５】
本発明は、上記事情に鑑みて為されたもので、高速溶接を行っても溶接部の酸素量が増加せず、溶接部のオーバーラップの発生を防止できるとともに、溶接部の衝撃性能の低下を防止することができるスパイラル溶接鋼管の製造方法を提供することを目的とする。
【０００６】
【課題を解決するための手段】
上記目的を達成するために、請求項１に記載のスパイラル溶接鋼管の製造方法は、表面にミルスケールが存在する鋼帯を螺旋状に成形しながら、前記鋼帯の幅方向端部同士をサブマージアーク溶接法により溶接し、スパイラル溶接鋼管を製造する方法であって、前記鋼帯の両端部のミルスケールを除去した後、高速で溶接することを特徴とする。
【０００７】
請求項１に記載の発明においては、溶接前に、熱延コイルに不可避的に発生するミルスケールのうち、溶接部およびその近傍となる鋼帯の両端部のミルスケールを除去する。これにより、溶接時にミルスケールが熱分解して酸素が溶接金属中に溶解することがない。したがって、溶接速度を速くしても、酸素量の増加を防止することができるので、溶接部のオーバーラップの発生を防止できるとともに、溶接部の衝撃性能の低下を防止することができる。
「高速で溶接する」とは、通常の２電極溶接法（例えば、１電極目の直流サブマージアーク溶接として２０００アンペア以下の溶接電流を用いる溶接法）では入力が不足して溶け込み不足が発生するような速度で溶接することをいい、この速度は、材料の板厚や製造される鋼管径などにより相違する。
【０００８】
請求項２に記載のスパイラル溶接鋼管の製造方法は、表面にミルスケールが存在する鋼帯を螺旋状に成形しながら、前記鋼帯の幅方向端部同士をサブマージアーク溶接法により溶接し、スパイラル溶接鋼管を製造する方法であって、前記鋼帯の両端部のミルスケールを除去した後、３以上の電極を用いて前記サブマージアーク溶接法による溶接を行うことを特徴とする。
【０００９】
請求項２に記載の発明においては、電極数が増えることにより、溶接部への入熱を増加させることができる。その結果、溶接速度を速くしても溶け込み不足を防止することができるので、高速溶接が可能となり、生産性を高めることができる。
【００１０】
請求項３に記載のスパイラル溶接鋼管の製造方法は、表面にミルスケールが存在する鋼帯を螺旋状に成形しながら、前記鋼帯の幅方向端部同士をサブマージアーク溶接法により溶接し、スパイラル溶接鋼管を製造する方法であって、前記鋼帯の両端部のミルスケールを除去した後、直流電流が２０００アンペア超である直流サブマージアーク溶接法による溶接と交流サブマージアーク溶接法による溶接とを併用する２電極溶接法によるサブマージアーク溶接法による溶接を行うことを特徴とする。
【００１１】
請求項３に記載の発明においては、直流サブマージアーク溶接に用いる直流電流を２０００アンペア超にすることにより、溶接部への入熱を増加させることができる。その結果、溶接速度を速くしても溶け込み不足を防止することができるので、高速溶接が可能となり、生産性を高めることができる。
【００１２】
請求項４に記載のスパイラル溶接鋼管の製造方法は、請求項１乃至請求項３のいずれかに記載の発明において、前記鋼帯のスケール除去が、鋼帯の両端部のみに施されることを特徴とする。
【００１３】
請求項４に記載の発明においては、溶接をするのに必要な鋼帯の両端部のみのミルスケールを除去しているので、ミルスケール除去作業が容易になる。
【００１４】
【発明の実施の形態】
以下、本発明の実施の形態に係るスパイラル溶接鋼管の製造方法を、図１を参照しつつ説明する。
まず、熱延コイル（鋼帯）１を巻き戻して、ロール（移動装置）により水平移動させる。鋼帯１を水平移動させる途中で、コイル継溶接２を行い、２つの鋼帯１の先端部と後端部を継なぎ合わせる。
【００１５】
次いで、レベラー３を通過させた後、鋼帯１を水平移動させながら、スケール除去装置４により、鋼帯１の両端部の表裏のミルスケールを除去する。スケール除去装置４は、例えば、グラインダーや回転式ワイヤブラシ等で構成され、鋼帯１の両端部の表面側および裏面側にそれぞれ配置され、水平移動してくる鋼帯１の両端部の表裏に接触しつつ回転し、鋼帯１の両端部の表裏のミルスケールを連続的に剥離する。剥離したミルスケールは、スケール除去装置４の両側に配置された集塵機５により吸引する。
このスケール除去装置４によるミルスケールの除去は、後の工程において、鋼帯１の端部同士がサブマージアーク溶接される際に、溶接部および溶接部近傍となる部分のミルスケールが除去される。
なお、鋼帯１の幅方向端部は、サイドトリマーなど（図示せず）でトリミングすることにより側面に新生面が生成されるので、トリミング工程を伴う場合は幅方向側面のスケールの除去を行う必要はない。
【００１６】
次いで、成形ロール６で鋼帯１を螺旋状に成形しながら、鋼帯１の合わせ部分となる端部同士を内面および外面からサブマージアーク溶接法により順次溶接していく。内面および外面のサブマージアーク溶接７，８はそれぞれ、通常、１電極目が直流サブマージアーク法による溶接で、２電極目が交流サブマージアーク溶接による溶接である２電極溶接法が用いられる。
この２電極溶接法による溶接において、直流サブマージアーク溶接に用いる直流電流は２０００アンペア超であることが望ましい。この直流電流を２０００アンペア超にすることにより、溶接部への入熱を増加させることができるので、溶接速度を早めても所要の溶け込み深さを確保することができる。したがって、高速溶接が可能となり、生産性を高めることができる。
【００１７】
なお、このような２電極法による溶接でなくても、３以上の電極を用いてサブマージアーク溶接を行うと、溶接部への入熱を増加させることができるので、溶接速度を早めても所要の溶け込み深さを確保することができ、したがって高速溶接が可能となり、生産性を高めることができる。
【００１８】
次いで、溶接により鋼管となったものを、切り出し装置９により所定の長さの鋼管に切断する。
【００１９】
このようなスパイラル溶接鋼管の製造方法にあっては、溶接前に、スケール除去装置４により鋼帯１の両端部の表裏のミルスケールを除去する。そのため、溶接時にミルスケールが熱分解して酸素が溶接金属中に溶解することがなく、したがって溶接速度を速くしても、酸素量の増加を防止することができるので、溶接部のオーバーラップの発生を防止できるとともに、溶接部の衝撃性能の低下を防止することができる。また、鋼帯１を水平移動させながら、スケール除去装置４により、鋼帯１の両端部の表裏のミルスケールを除去するので、ミルスケール除去作業が容易であるとともに、除去作業の高速化を図ることができて、生産性を高めることができる。スケールの除去装置４、集塵装置５等の位置は適宜決定すればよい。
【００２０】
【実施例】
以下、実施例により本発明をより具体的に説明する。
図１に示すスパイラル溶接鋼管の製造方法によりスパイラル鋼管を製造した。
すなわち、まず、材質が一般構造用炭素鋼鋼管ＳＴＫ４００（ＪＩＳ　Ｇ　３４４４）用の熱延コイル（鋼帯）１を巻き戻して、ロールにより水平移動させ、次いで、レベラー３を通過させた後、鋼帯１を水平移動させながら、グラインダー（スケール除去装置）４により、鋼帯１の表裏において、両端部２０ｍｍずつの範囲で、ミルスケールを除去した。
【００２１】
次いで、成形ロール６で鋼帯１を螺旋状に成形しながら、鋼帯１の合わせ部分となる端部同士を内面および外面からサブマージアーク溶接法により順次溶接し、製管寸法が外径１２００ｍｍφ、板厚１６ｍｍ、長さ１ｍのスパイラル溶接鋼管を製造した。
内面および外面のサブマージアーク溶接７，８はそれぞれ、１電極目が直流サブマージアーク法による溶接で、２電極目が交流サブマージアーク溶接による溶接である２電極溶接法を用いた。
内面および外面のサブマージアーク溶接７，８の各溶接の溶接速度を変え、また溶接速度が速くなるにつれて溶接電流を高くして、５種類のスパイラル溶接鋼管を製造した。表１において、Ｎｏ．６〜Ｎｏ．１０がこれらの溶接鋼管である。
【００２２】
【表１】

Figure 2004017134
【００２３】
比較例として、ミルスケールを除去しない以外は、上記と同様にしてスパイラル溶接鋼管を製造した。表１において、Ｎｏ．１〜Ｎｏ．５がこれらのスパイラル溶接鋼管である。
【００２４】
このようにして製造した各スパイラル溶接鋼管について、溶接金属（溶金）中の酸素量、溶接部のオーバーラップの有無、およびシャルピー衝撃試験により溶接部（溶接金属）中央部の０℃における衝撃値をそれぞれ調査した。この結果を表１に示した。
なお、シャルピー衝撃試験は、製造したスパイラル溶接鋼管からＪＩＳＺ２２０２に規定されたＶノッチ試験片を作製して、ＪＩＳＺ２２４２の金属材料衝撃試験方法に従って行った。
【００２５】
表１から分かるように、比較例Ｎｏ．１〜Ｎｏ．５では、熱延コイル（鋼帯）のミルスケールを除去せずに、溶接速度を２．６〜３．５Ｍ／分にすると、溶接金属中の酸素量が７１０〜９４０ｐｐｍであった。このうち、溶接速度が３．０〜３．５Ｍ／分の比較例Ｎｏ．３〜Ｎｏ．５では、溶接金属中の酸素量が７８０〜９４０ｐｐｍであり、溶接部にオーバーラップが発生した。
これに対し、実施例Ｎｏ．６〜Ｎｏ．１０では、熱延コイルの両端部表裏（溶接部およびその近傍）のミルスケールを除去しており、溶接速度を２．６〜３．５Ｍ／分にしても、溶接金属中の酸素量が５３０〜６７０ｐｐｍと低く、すべての実施例で溶接部にオーバーラップが発生しなかった。
【００２６】
また、比較例Ｎｏ．１〜Ｎｏ．５では、溶接速度を２．６〜３．５Ｍ／分にすると、溶接部中央部の０℃における衝撃値が３０〜１５Ｊに低下した。
これに対し、実施例Ｎｏ．６〜Ｎｏ．１０では、溶接速度を２．６〜３．５Ｍ／分にしても、溶接部中央部の０℃における衝撃値が６１〜３７Ｊであり、溶接部の衝撃性能の低下を防止することができた。
【００２７】
また、実施例Ｎｏ．６〜Ｎｏ．１０はいずれも、２電極溶接法による溶接において、直流サブマージアーク溶接の直流電流をおよそ２０００アンペア超として、溶接部への入熱を増加させて溶け込み不足を防止し、これにより溶接速度が２．６〜３．５Ｍ／分の高速溶接を可能にしている。
【００２８】
このように、熱延コイルの両端部表裏（溶接部およびその近傍）のミルスケールを除去してから、サブマージアーク溶接を行うことにより、高速で溶接しても溶接金属中の酸素量をおよそ７００ｐｐｍ以下にすることができる。したがって、高速で溶接しても、オーバーラップの発生を防止することができ、かつ溶接部中央部の０℃における衝撃値をおよそ３０Ｊ以上とすることができる。
【００２９】
【発明の効果】
以上説明したように、本発明のスパイラル溶接鋼管の製造方法によれば、高速溶接を行っても溶接部の酸素量が増加せず、溶接部のオーバーラップの発生を防止できるとともに、溶接部の衝撃性能の低下を防止することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態に係るスパイラル溶接鋼管の製造方法を説明するための図である。
【図２】溶鉄の表面張力に及ぼす酸素の影響を示すグラフである。
【図３】オーバーラップを説明するための図である。
【符号の説明】
１　　鋼帯
４　　スケール除去装置
６　　成形ロール
７，８　　サブマージアーク溶接[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a spiral welded steel pipe.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, spirally welded steel pipes have been produced by welding hot rolled coils in a spiral shape and welding the ends to be joined together by a submerged arc welding method.
In the production of spiral welded steel pipes by this submerged arc welding, if the welding speed is increased to increase productivity, insufficient heat input to the weld will occur and insufficient penetration will occur. In general, increasing the number of electrodes or increasing the number of electrodes is generally performed.
[0003]
[Problems to be solved by the invention]
However, such a method can solve the heat input deficiency, but increases the welding speed, thereby increasing the amount of oxygen in the weld metal, causing a defect called overlap or impact performance. Is reduced.
[0004]
That is, the mill scale (iron oxide) generated on the surface of the hot-rolled coil is thermally decomposed by heat at the time of welding to generate oxygen, and the oxygen is dissolved in the weld metal. When the welding speed is not so high, the dissolved oxygen can take a sufficient time for the deoxidation reaction by the flux and is not a problem because it is deoxidized.However, when the welding speed is increased, the deoxidation reaction by the flux is increased. The time required for the treatment becomes insufficient and deoxidation becomes difficult, and the amount of oxygen increases.
FIG. 2 is a diagram shown in “Handbook of Physical Properties of Molten Iron and Fusing” (published by the Iron and Steel Institute of Japan). FIG. 6 is a diagram in which the horizontal axis represents the oxygen amount O (wt%) and the vertical axis represents the surface tension γ (dyne / cm) regarding the attractive force for dropping the molten metal having different oxygen amounts into the capillary tube. Two examples ((2) and (3) in the figure) are shown for the case of 1570 ° C ((1) in the figure) and the case of 1550 ° C. It can be seen that as the amount of oxygen increases, the surface tension decreases.
When the surface tension is reduced, there is a problem that an overlap as shown in FIG. 3 occurs at both ends of the welding beat and the impact performance of the welded portion is reduced.
[0005]
The present invention has been made in view of the above circumstances, and even when high-speed welding is performed, the amount of oxygen in the welded portion does not increase, and it is possible to prevent the occurrence of overlap of the welded portion and to reduce the impact performance of the welded portion. It is an object of the present invention to provide a method for manufacturing a spirally welded steel pipe that can prevent the occurrence of cracks.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the method for manufacturing a spiral welded steel pipe according to claim 1, wherein the steel strip having a mill scale on its surface is spirally formed while submerging the widthwise ends of the steel strip. A method of manufacturing a spirally welded steel pipe by welding by an arc welding method, wherein a high-speed welding is performed after removing mill scales at both ends of the steel strip.
[0007]
In the first aspect of the present invention, before welding, mill scales at both ends of the steel strip near the weld and the vicinity thereof are removed from mill scales inevitably generated in the hot-rolled coil. This prevents the mill scale from being thermally decomposed during welding and oxygen from being dissolved in the weld metal. Therefore, even if the welding speed is increased, an increase in the amount of oxygen can be prevented, so that it is possible to prevent the occurrence of overlap of the welded portion and to prevent the impact performance of the welded portion from being reduced.
"Welding at high speed" means that in a normal two-electrode welding method (for example, a welding method using a welding current of 2000 amperes or less as DC submerged arc welding of the first electrode), insufficient input occurs and insufficient penetration occurs. This means that welding is performed at an appropriate speed, and this speed differs depending on the thickness of the material, the diameter of the steel pipe to be manufactured, and the like.
[0008]
The method for manufacturing a spiral-welded steel pipe according to claim 2, wherein the widthwise ends of the steel strip are welded to each other by a submerged arc welding method while spirally forming a steel strip having a mill scale on the surface, thereby forming a spiral. A method for manufacturing a welded steel pipe, wherein the mill scale at both ends of the steel strip is removed, and then welding is performed by the submerged arc welding method using three or more electrodes.
[0009]
According to the second aspect of the present invention, the heat input to the weld can be increased by increasing the number of electrodes. As a result, insufficient penetration can be prevented even when the welding speed is increased, so that high-speed welding can be performed and productivity can be increased.
[0010]
The method for manufacturing a spiral-welded steel pipe according to claim 3, wherein the steel strip having a mill scale on its surface is spirally formed, and the widthwise ends of the steel strip are welded to each other by a submerged arc welding method. A method for producing a welded steel pipe, in which, after removing mill scale at both ends of the steel strip, a combination of welding using a DC submerged arc welding method and a welding method using an AC submerged arc welding method in which a DC current is more than 2,000 amperes. It is characterized by performing welding by a submerged arc welding method using a two-electrode welding method.
[0011]
According to the third aspect of the present invention, the heat input to the weld can be increased by setting the DC current used for DC submerged arc welding to be more than 2000 amperes. As a result, insufficient penetration can be prevented even when the welding speed is increased, so that high-speed welding can be performed and productivity can be increased.
[0012]
According to a fourth aspect of the present invention, in the method for manufacturing a spiral welded steel pipe according to any one of the first to third aspects, the scale removal of the steel strip is performed only at both ends of the steel strip. Features.
[0013]
According to the fourth aspect of the present invention, since mill scales only at both ends of the steel strip required for welding are removed, the mill scale removing operation is facilitated.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for manufacturing a spiral welded steel pipe according to an embodiment of the present invention will be described with reference to FIG.
First, the hot-rolled coil (steel strip) 1 is unwound and horizontally moved by a roll (moving device). During the horizontal movement of the steel strip 1, the coil welding 2 is performed, and the front end and the rear end of the two steel strips 1 are joined.
[0015]
Next, after passing through the leveler 3, the steel strip 1 is horizontally moved and the scale remover 4 removes the mill scales on both sides of the steel strip 1 from the front and back. The scale removing device 4 is composed of, for example, a grinder or a rotary wire brush, and is disposed on the front side and the back side of the both ends of the steel strip 1, respectively. It rotates while contacting, and continuously peels off the mill scale on both sides of the steel strip 1. The peeled mill scale is sucked by dust collectors 5 arranged on both sides of the scale removing device 4.
In the removal of the mill scale by the scale removing device 4, when the ends of the steel strip 1 are subjected to submerged arc welding in a later step, the mill scale at the welded portion and the portion near the welded portion is removed.
In addition, since the width direction end of the steel strip 1 is trimmed by a side trimmer or the like (not shown), a new surface is generated on the side surface. When a trimming process is involved, it is necessary to remove scale on the width direction side surface. There is no.
[0016]
Next, while the steel strip 1 is spirally formed by the forming rolls 6, the ends to be joined together of the steel strip 1 are sequentially welded from the inner surface and the outer surface by a submerged arc welding method. For each of the inner and outer submerged arc weldings 7, 8, a two-electrode welding method is generally used, in which the first electrode is welding by DC submerged arc welding and the second electrode is welding by AC submerged arc welding.
In the welding by the two-electrode welding method, the DC current used for DC submerged arc welding is desirably more than 2000 amperes. By setting the DC current to more than 2000 amps, the heat input to the weld can be increased, so that the required penetration depth can be secured even if the welding speed is increased. Therefore, high-speed welding can be performed, and productivity can be improved.
[0017]
Even if the welding is not performed by such a two-electrode method, if submerged arc welding is performed using three or more electrodes, the heat input to the welded portion can be increased. Therefore, the penetration depth can be ensured, so that high-speed welding can be performed, and the productivity can be increased.
[0018]
Next, the steel pipe formed by welding is cut into steel pipes of a predetermined length by the cutting device 9.
[0019]
In such a method for manufacturing a spiral welded steel pipe, the mill scale on both sides of the steel strip 1 is removed by the scale removing device 4 before welding. Therefore, the mill scale is not thermally decomposed during welding and oxygen is not dissolved in the weld metal.Thus, even if the welding speed is increased, an increase in the amount of oxygen can be prevented. The occurrence can be prevented, and the impact performance of the welded portion can be prevented from lowering. Moreover, since the scale remover 4 removes the mill scales on both sides of the steel strip 1 while moving the steel strip 1 horizontally, the mill scale removal operation is easy and the speed of the removal operation is increased. Can increase productivity. The positions of the scale removing device 4, the dust collecting device 5, and the like may be appropriately determined.
[0020]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples.
A spiral steel pipe was manufactured by the method for manufacturing a spiral welded steel pipe shown in FIG.
That is, first, the hot-rolled coil (steel strip) 1 for carbon steel pipe STK400 (JIS G 3444) for general structural use is rewound, horizontally moved by a roll, and then passed through the leveler 3, While moving the strip 1 horizontally, the mill scale was removed by a grinder (scale removing device) 4 on both sides of the steel strip 1 in a range of 20 mm at both ends.
[0021]
Next, while the steel strip 1 is spirally formed by the forming roll 6, the ends to be joined of the steel strip 1 are sequentially welded from the inner surface and the outer surface by a submerged arc welding method. A spiral welded steel pipe having a thickness of 16 mm and a length of 1 m was manufactured.
Each of the inner and outer submerged arc weldings 7, 8 used a two-electrode welding method in which the first electrode was welded by the DC submerged arc method and the second electrode was welded by the AC submerged arc welding.
Five kinds of spiral welded steel pipes were manufactured by changing the welding speed of each of the inner and outer submerged arc weldings 7 and 8 and increasing the welding current as the welding speed increased. In Table 1, No. 6-No. Reference numeral 10 denotes these welded steel pipes.
[0022]
[Table 1]
Figure 2004017134
[0023]
As a comparative example, a spiral welded steel pipe was manufactured in the same manner as described above except that the mill scale was not removed. In Table 1, No. 1 to No. 5 is these spiral welded steel pipes.
[0024]
For each of the spiral welded steel pipes thus manufactured, the amount of oxygen in the weld metal (metal melt), the presence or absence of overlap of the weld, and the impact value at 0 ° C. of the center of the weld (weld metal) by a Charpy impact test. Were investigated respectively. The results are shown in Table 1.
In addition, the Charpy impact test was performed according to the metal material impact test method of JISZ2242 by preparing a V-notch test piece specified in JISZ2202 from the manufactured spiral welded steel pipe.
[0025]
As can be seen from Table 1, Comparative Example No. 1 to No. In No. 5, when the welding speed was set to 2.6 to 3.5 M / min without removing the mill scale of the hot-rolled coil (steel strip), the oxygen content in the weld metal was 710 to 940 ppm. Among them, Comparative Example No. having a welding speed of 3.0 to 3.5 M / min. 3-No. In No. 5, the amount of oxygen in the weld metal was 780 to 940 ppm, and an overlap occurred in the welded portion.
On the other hand, in Example No. 6-No. In No. 10, the mill scale on both sides of the hot-rolled coil (at and near the welded portion) was removed, and even if the welding speed was 2.6 to 3.5 M / min, the oxygen amount in the weld metal was 530. 670 ppm, and no overlap occurred in the welds in all Examples.
[0026]
In Comparative Example No. 1 to No. In No. 5, when the welding speed was set to 2.6 to 3.5 M / min, the impact value at 0 ° C. at the center of the welded portion was reduced to 30 to 15 J.
On the other hand, in Example No. 6-No. In No. 10, even when the welding speed was 2.6 to 3.5 M / min, the impact value at 0 ° C. of the central portion of the welded portion was 61 to 37 J, and a decrease in the impact performance of the welded portion could be prevented. .
[0027]
Also, in Example No. 6-No. In any of the methods 10, in the welding by the two-electrode welding method, the DC current of the DC submerged arc welding is increased to about 2000 amperes, thereby increasing the heat input to the welded portion to prevent insufficient penetration, thereby increasing the welding speed to 2. High-speed welding of 6 to 3.5 M / min is possible.
[0028]
As described above, by removing the mill scale on both sides of the hot-rolled coil (at and near the welded portion) and then performing submerged arc welding, the amount of oxygen in the weld metal can be reduced to about 700 ppm even at high speed welding. It can be: Therefore, even when welding is performed at a high speed, the occurrence of overlap can be prevented, and the impact value at 0 ° C. of the central portion of the welded portion can be made about 30 J or more.
[0029]
【The invention's effect】
As described above, according to the method for manufacturing a spiral welded steel pipe of the present invention, even when high-speed welding is performed, the amount of oxygen in the welded portion does not increase, and it is possible to prevent the occurrence of overlap of the welded portion, and to prevent the welded portion from being overlapped. A drop in impact performance can be prevented.
[Brief description of the drawings]
FIG. 1 is a view for explaining a method for manufacturing a spiral welded steel pipe according to an embodiment of the present invention.
FIG. 2 is a graph showing the effect of oxygen on the surface tension of molten iron.
FIG. 3 is a diagram for explaining overlap;
[Explanation of symbols]
Reference Signs List 1 steel strip 4 scale removing device 6 forming roll 7, 8 submerged arc welding

Claims (4)

表面にミルスケールが存在する鋼帯を螺旋状に成形しながら、前記鋼帯の幅方向端部同士をサブマージアーク溶接法により溶接し、スパイラル溶接鋼管を製造する方法であって、
前記鋼帯の両端部のミルスケールを除去した後、高速で溶接することを特徴とするスパイラル溶接鋼管の製造方法。A method of manufacturing a spiral-welded steel pipe, by forming a steel strip having a mill scale on the surface in a spiral shape, welding the widthwise ends of the steel strip by a submerged arc welding method,
A method for manufacturing a spirally welded steel pipe, comprising: removing mill scales at both ends of the steel strip and welding at a high speed. 表面にミルスケールが存在する鋼帯を螺旋状に成形しながら、前記鋼帯の幅方向端部同士をサブマージアーク溶接法により溶接し、スパイラル溶接鋼管を製造する方法であって、
前記鋼帯の両端部のミルスケールを除去した後、３以上の電極を用いて前記サブマージアーク溶接法による溶接を行うことを特徴とするスパイラル溶接鋼管の製造方法。A method of manufacturing a spiral-welded steel pipe, by forming a steel strip having a mill scale on the surface in a spiral shape, welding the widthwise ends of the steel strip by a submerged arc welding method,
A method for manufacturing a spiral-welded steel pipe, comprising: after removing mill scales at both ends of the steel strip, performing welding by the submerged arc welding method using three or more electrodes. 表面にミルスケールが存在する鋼帯を螺旋状に成形しながら、前記鋼帯の幅方向端部同士をサブマージアーク溶接法により溶接し、スパイラル溶接鋼管を製造する方法であって、
前記鋼帯の両端部のミルスケールを除去した後、直流電流が２０００アンペア超である直流サブマージアーク溶接法による溶接と交流サブマージアーク溶接法による溶接とを併用する２電極溶接法によるサブマージアーク溶接法による溶接を行うことを特徴とするスパイラル溶接鋼管の製造方法。A method of manufacturing a spiral-welded steel pipe, by forming a steel strip having a mill scale on the surface in a spiral shape, welding the widthwise ends of the steel strip by a submerged arc welding method,
After removing the mill scale at both ends of the steel strip, a submerged arc welding method using a two-electrode welding method using a combination of welding by a DC submerged arc welding method and a welding method by an AC submerged arc welding method in which a DC current is more than 2000 amps A method for producing a spirally welded steel pipe, characterized by performing welding by a method. 前記鋼帯のスケール除去が、鋼帯の両端部のみに施されることを特徴とする請求項１乃至請求項３のいずれかに記載のスパイラル溶接鋼管の製造方法。The method for producing a spiral welded steel pipe according to any one of claims 1 to 3, wherein the scale removal of the steel strip is performed only on both ends of the steel strip.
JP2002179408A 2002-06-20 2002-06-20 Method for manufacturing spiral welded steel pipe Pending JP2004017134A (en)

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Publication number Priority date Publication date Assignee Title
KR100917474B1 (en) * 2008-01-03 2009-09-14 함형춘 Spiral-pipe of Production-equipment
CN101797600B (en) * 2010-02-23 2012-05-23 华油钢管有限公司 Method for manufacturing high-strength X100 steel grade spiral seam submerged arc welded pipe
CN102784812A (en) * 2012-08-03 2012-11-21 中国石油集团渤海石油装备制造有限公司 Manufacturing method of X65 steel-grade HFW (High Frequency Welding) steel pipe for ore pulp conveying pipeline
CN103831509A (en) * 2014-03-15 2014-06-04 宝鸡石油钢管有限责任公司 Spiral submerged arc steel tube welding procedure qualification method
JP2015120194A (en) * 2013-11-20 2015-07-02 新日鐵住金株式会社 Scale removal device in electric resistance welded steel pipe production line
CN109317983A (en) * 2018-11-28 2019-02-12 宝鸡石油钢管有限责任公司 Skid spiral submerged welded pipe unit
CN109719156A (en) * 2019-03-06 2019-05-07 杨胜 A kind of high efficiency steel band pipe production method

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100917474B1 (en) * 2008-01-03 2009-09-14 함형춘 Spiral-pipe of Production-equipment
CN101797600B (en) * 2010-02-23 2012-05-23 华油钢管有限公司 Method for manufacturing high-strength X100 steel grade spiral seam submerged arc welded pipe
CN102784812A (en) * 2012-08-03 2012-11-21 中国石油集团渤海石油装备制造有限公司 Manufacturing method of X65 steel-grade HFW (High Frequency Welding) steel pipe for ore pulp conveying pipeline
JP2015120194A (en) * 2013-11-20 2015-07-02 新日鐵住金株式会社 Scale removal device in electric resistance welded steel pipe production line
CN103831509A (en) * 2014-03-15 2014-06-04 宝鸡石油钢管有限责任公司 Spiral submerged arc steel tube welding procedure qualification method
CN109317983A (en) * 2018-11-28 2019-02-12 宝鸡石油钢管有限责任公司 Skid spiral submerged welded pipe unit
CN109719156A (en) * 2019-03-06 2019-05-07 杨胜 A kind of high efficiency steel band pipe production method

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