JP2006144109A - Electric resistance welded tube having excellent crack resistance in weld zone and its production method - Google Patents

Electric resistance welded tube having excellent crack resistance in weld zone and its production method Download PDF

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JP2006144109A
JP2006144109A JP2004339533A JP2004339533A JP2006144109A JP 2006144109 A JP2006144109 A JP 2006144109A JP 2004339533 A JP2004339533 A JP 2004339533A JP 2004339533 A JP2004339533 A JP 2004339533A JP 2006144109 A JP2006144109 A JP 2006144109A
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welded
steel pipe
crack resistance
welding
oxide inclusions
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Toru Fujimura
亨 藤村
Wataru Tanimoto
亘 谷本
Hisato Noro
寿人 野呂
Hiroyasu Yokoyama
泰康 横山
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JFE Steel Corp
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JFE Steel Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a welded steel tube having excellent crack resistance in a weld zone, and to provide its production method. <P>SOLUTION: In the cross-section of the weld zone, the number of oxide based inclusions with a grain size of ≥3 μm is controlled to ≤2 pieces/mm<SP>2</SP>, the number of the oxide based inclusions is measured, preferably, by an electron beam microprobe analysis process, and, regarding the method for controlling welding conditions, as the atmosphere at the time of welding, inert gas such as N<SB>2</SB>is used, and the concentration of oxygen in the gas is controlled to ≤60 ppm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、電縫鋼管およびその製造方法に関し、特に溶接部の耐割れ性に優れるものに関する。   The present invention relates to an electric resistance welded steel pipe and a method for producing the same, and more particularly to a material excellent in crack resistance of a weld.

鋼管の用途は、パイプライン用、機械構造部材用、熱交換器用、自動車部品用、各種プラント用等多岐にわたっており、その用途またはサイズに応じて、各種の方法により製造された継目無鋼管や溶接鋼管が使用されている。   Steel pipes are used for various purposes such as pipelines, machine structural members, heat exchangers, automotive parts, and various plants. Seamless steel pipes and welds manufactured by various methods according to their use or size. Steel pipe is used.

その中で、鋼帯を連続的に管状に成形して管状体（オープンパイプ）となし、その相対する両エッジ部を高周波加熱または抵抗加熱によって加熱し、溶接することにより製管される電縫鋼管はその寸法精度が高く、他の製造方法に比較して高能率に製造することができ、且つ、比較的安価であるために従来から多量に製造使用されている。   Among them, a steel strip is continuously formed into a tubular shape to form a tubular body (open pipe), and both opposing edge portions are heated by high-frequency heating or resistance heating and welded to be electroformed. Steel pipes have high dimensional accuracy, can be manufactured with higher efficiency than other manufacturing methods, and are relatively inexpensive, so that they are conventionally manufactured and used in large quantities.

しかしながら、電縫鋼管を高度の材料特性や高い信頼性が要求される分野において使用する場合、溶接部に酸化物系介在物が多く割れ発生の原因となるため溶接部の健全性確保が問題となる。   However, when using ERW pipes in fields where high material properties and high reliability are required, there are many oxide inclusions in the weld and cause cracking. Become.

他の溶接鋼管と比較して電縫鋼管の溶接部において酸化物系介在物が多い理由は電縫溶接法がアーク溶接などの溶融溶接と圧接との中間的な溶接法であり、その接合部に明瞭な溶融プールが形成されず、溶接時に酸化によって形成された相当量の酸化物が鋼の内部から排除されにくいためとされている。   The reason why there are more oxide inclusions in welded parts of ERW pipes compared to other welded pipes is that ERW welding is an intermediate welding method between fusion welding such as arc welding and pressure welding. This is because a clear molten pool is not formed, and a considerable amount of oxide formed by oxidation during welding is difficult to be removed from the inside of the steel.

酸素含有量の多い溶接部は機械的特性が劣化し、割れの原因となる。そのため、種々の方法、例えば、溶接部を非酸化性ガスでシールドして電縫溶接を行い溶接時に鋼帯を管状体にアップセットして、介在物などを可能な限り外部に排出したりして溶接部の酸素含有量を低減することが提案されている。   A weld with a high oxygen content deteriorates mechanical properties and causes cracking. For this reason, various methods, for example, shielding the weld with a non-oxidizing gas and performing electric resistance welding, upsetting the steel strip to a tubular body during welding, and discharging inclusions as much as possible to the outside. It has been proposed to reduce the oxygen content of the weld.

特許文献１には非酸化性ガスで接合端部をシールドして電縫溶接を行い、アップセット量を溶接管肉厚に対して規定し、溶接部の酸素量や介在物を減少させる方法が開示されている。   Patent Document 1 discloses a method in which the joint end is shielded with a non-oxidizing gas and electro-welding welding is performed, the upset amount is regulated with respect to the welded pipe wall thickness, and the oxygen amount and inclusions in the welded portion are reduced. It is disclosed.

非酸化性雰囲気として窒素、アルゴンを使用し、シールボックスを設けて溶接部を非酸化性に保って酸化物の生成を抑制し、更に接合不良と非金属介在物が溶接部の表面に現れるのを防止するようにアップセットを行い、溶接部の介在物割れを防止することを特徴とする。   Nitrogen and argon are used as a non-oxidizing atmosphere, and a seal box is provided to keep the welded portion non-oxidizing to suppress the formation of oxides. Further, poor bonding and non-metallic inclusions appear on the surface of the welded portion. It is characterized in that upset is performed so as to prevent cracking of inclusions in the welded portion.

特許文献２は溶接部の酸素量を２００ppm以下とするものであるが、管状体の付き合わされたエッジ部を特定の温度範囲内に予熱後、レーザビームにより照射して溶融後溶接してアップセットし、鋼の酸素量の大部分を占める酸化物を鋼管の外部に排出することを特徴とする。   In Patent Document 2, the oxygen content of the welded portion is set to 200 ppm or less, but the edge portion where the tubular body is attached is preheated within a specific temperature range, irradiated with a laser beam, and welded after melting. In addition, the oxide occupying most of the oxygen content of the steel is discharged to the outside of the steel pipe.

特許文献３は窒素、アルゴンなどの非酸化性ガスで溶接部をシールドすると共に、高周波加熱中の溶接部位にレーザビームまたはプラズマアークを照射し、圧接される部位をより高温とし、液状酸化物を排出しやすくし、溶接欠陥を効果的に防止することを特徴とする。
特開昭６３−２４１１１６号公報 特開平９−１９４９９８号公報 特開平５−２３８６７号公報 Patent Document 3 shields the weld with a non-oxidizing gas such as nitrogen or argon, irradiates the welded part during high-frequency heating with a laser beam or a plasma arc, and raises the pressure-contacted part to a higher temperature. It is characterized by facilitating discharge and effectively preventing welding defects.
JP 63-241116 A JP-A-9-194998 JP-A-5-23867

しかしながら、溶接部を非酸化性ガスでシールドする方法はシールド状況と酸化物の生成防止効果の関係が明確でなく、また、溶接部をレーザビーム等で加熱してアップセットによる酸化物の排出を容易としても、介在物などが完全に排除されるわけではなく、相当量の介在物が残留して鋼中の酸素量を増大させるため、溶接部の強度や靭性などの機械的性質が母材部と遜色のない電縫溶接鋼管は従来は製造し得ないものとされ、その用途が制限される大きな原因となっていた。   However, the method of shielding the weld with a non-oxidizing gas does not clearly show the relationship between the shielding situation and the effect of preventing the formation of oxides, and the weld is heated with a laser beam or the like to discharge oxides by upset. Even if easy, inclusions and the like are not completely eliminated, but a considerable amount of inclusions remain and increase the amount of oxygen in the steel, so the mechanical properties such as the strength and toughness of the welded part are the base material. Conventionally, the ERW welded steel pipe, which is inferior to the parts, is considered to be impossible to manufacture in the past, which has been a major cause of limiting its application.

そこで本発明は健全な溶接部の得られるシールド状態を示す定量的な指針を明らかとし、溶接部の強度や靭性などの機械的性質が母材部と同等で、用途の制限が少ない電縫鋼管及びその製造方法を提供することを目的とする。   Therefore, the present invention clarifies a quantitative guideline indicating a shield state in which a sound welded portion can be obtained, and has the same mechanical properties as the base metal part, such as the strength and toughness of the welded part, and has less restrictions on applications. And it aims at providing the manufacturing method.

本発明者等は電縫溶接部の機械的性質が母材部に比較して劣る原因について１溶接部の酸素量、介在物量、２溶接部の熱履歴、３溶接部近傍のメタルフローの観点から鋭意検討を行い、これらのうち特に１溶接部の酸素量、介在物量の影響が大きいことを見出し、研究を重ねた。   As for the cause of the mechanical properties of the ERW welded part being inferior to that of the base metal part, the inventors of the present invention have the following points: 1) the amount of oxygen in the welded part, 2) the amount of inclusions, 2) the heat history of the welded part From these researches, we found that the effects of oxygen and inclusions in one weld were particularly significant, and repeated research.

その結果、溶接部において特定の寸法以上となる大きな酸化物系介在物の個数を制限すると、溶接部における酸化物系介在物の総数を低減できることを知見した。本発明は得られた知見を元に更に検討を加えてなされたものであり、すなわち本発明は、
１ 溶接部断面において粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下であることを特徴とする溶接部の耐割れ性に優れる電縫鋼管。
２ 前記酸化物系介在物の個数を電子線マイクロプローブ分析法により求めることを特徴とする１記載の溶接部の耐割れ性に優れる電縫鋼管。 As a result, it has been found that the total number of oxide inclusions in the weld can be reduced by limiting the number of large oxide inclusions having a specific dimension or more in the weld. The present invention has been made based on further findings based on the knowledge obtained, that is, the present invention
1. An ERW steel pipe excellent in crack resistance of a welded portion, characterized in that the number of oxide inclusions having a particle size of 3 μm or more in a welded section is 2 pieces / mm 2 or less.
2 The number of the oxide inclusions is obtained by an electron beam microprobe analysis method, wherein the welded steel pipe is excellent in crack resistance of the welded portion.

３ 溶接部断面において粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下となるように溶接条件を調整することを特徴とする溶接部の耐割れ性に優れる電縫鋼管の製造方法。 3. ERW steel pipe with excellent crack resistance in welds, characterized by adjusting welding conditions so that the number of oxide inclusions with a particle size of 3 μm or more in the weld cross section is 2 / mm 2 or less Manufacturing method.

４ 前記溶接条件の調整方法として、溶接の際の雰囲気を不活性ガスとし、当該ガス中の酸素濃度を６０ppm以下とすることを特徴とする３に記載の溶接部の耐割れ性に優れる電縫鋼管の製造方法。   4 The welding method according to 3 above, wherein the welding conditions are adjusted by using an inert gas atmosphere and the oxygen concentration in the gas is 60 ppm or less. Steel pipe manufacturing method.

本発明によれば溶接部における酸化物系介在物の数が少なく、溶接部の耐割れ性に優れ、母材部と比較して遜色のない機械的性質を有する溶接部を備えた電縫鋼管が得られ産業上極めて有用である。   According to the present invention, the number of oxide inclusions in the welded portion is small, the welded portion is excellent in crack resistance, and an ERW steel pipe having a welded portion having mechanical properties comparable to the base metal portion is obtained. It is extremely useful in industry.

本発明は電縫溶接する際の溶接条件を、溶接部断面において酸化物系介在物を電子線マイクロプローブ分析装置（ＥＰＭＡ）で測定して、粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下となる条件とすることを特徴とする。 According to the present invention, the number of oxide inclusions having a particle size of 3 μm or more is measured by measuring the electron inclusions in the cross section of the weld with an electron beam microprobe analyzer (EPMA). It is a condition that is 2 pieces / mm 2 or less.

図１は本発明を実施する製管設備の一例を示す概略説明図で、図において１は電縫溶接され、電縫鋼管となる管状体、２はシールド装置、３はワークコイル、４はスクイズロール、５は管状体１のエッジ部、ａは管状体１のエッジ部５が最初に突きあって形成される溶接点を示す。   FIG. 1 is a schematic explanatory view showing an example of a pipe making facility for carrying out the present invention. In the figure, 1 is a tubular body that is electro-welded and becomes an electric-welded steel pipe, 2 is a shield device, 3 is a work coil, and 4 is a squeeze. The roll 5 is an edge portion of the tubular body 1, and a is a welding point formed by the edge portion 5 of the tubular body 1 striking first.

図示した製管設備では、鋼帯を多段ロール（図では省略）によって管状体１に成形し、シールド装置２内において、前記管状体１のエッジ部５を突合せた部分をワークコイル３により加熱溶融後、スクイズロール４によりアップセットし電縫鋼管を製造する。
本発明では、シールド装置２内において管状体１をワークコイル３により加熱溶融する際の溶接条件を、溶接後において電縫鋼管から切り出した溶接部断面における酸化物系介在物をＥＰＭＡで測定して、粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下となる条件に規定する。 In the illustrated pipe making equipment, a steel strip is formed into a tubular body 1 by a multi-stage roll (not shown), and a portion where the edge portion 5 of the tubular body 1 is abutted in the shield device 2 is heated and melted by a work coil 3. Thereafter, the squeeze roll 4 is used for upsetting to produce an ERW steel pipe.
In the present invention, welding conditions when the tubular body 1 is heated and melted by the work coil 3 in the shield device 2 are measured by EPMA for oxide inclusions in a welded section cut out from the ERW steel pipe after welding. The condition is such that the number of oxide inclusions having a particle size of 3 μm or more is 2 / mm 2 or less.

酸化物系介在物の測定は、ＥＰＭＡで行うことが好ましい。図２にＥＰＭＡの概略図を示す。電子銃１１から試料１２に照射された電子ビームは、試料１２で二次電子、反射電子および蛍光Ｘ線を発生させる。二次電子、反射電子は二次電子検出器１３および反射電子検出器１４で検出される。蛍光X線は分光結晶１５により分光され、検出器１６により検出され試料１２を同定する。   The oxide inclusions are preferably measured by EPMA. FIG. 2 shows a schematic diagram of EPMA. The electron beam applied to the sample 12 from the electron gun 11 generates secondary electrons, reflected electrons, and fluorescent X-rays in the sample 12. Secondary electrons and reflected electrons are detected by the secondary electron detector 13 and the reflected electron detector 14. The fluorescent X-ray is dispersed by the spectroscopic crystal 15 and detected by the detector 16 to identify the sample 12.

電縫鋼管溶接部における酸化物系介在物の測定条件は分析領域を4mm×4mm とし、電圧１５kV，電流３００nA、ビーム径0.5μm、積分時間３０sec とすることが好ましい。尚、ＥＰＭＡに替わりエネルギー分散型Ｘ線検出器（ＥＤＸ）を装着して元素分析を行っても良い。   The measurement conditions for oxide inclusions in the welded portion of the ERW steel pipe are preferably an analysis region of 4 mm × 4 mm, a voltage of 15 kV, a current of 300 nA, a beam diameter of 0.5 μm, and an integration time of 30 sec. Instead of EPMA, an elemental analysis may be performed by mounting an energy dispersive X-ray detector (EDX).

本発明に係る電縫鋼管の溶接条件は、電縫鋼管から切り出した溶接部断面において粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下となる溶接条件とする。前記溶接条件は、溶接の際の雰囲気をN2などの不活性ガスとし、当該ガス中の酸素濃度を６０ppm以下とすることにより可能である。尚、本発明において溶接部断面とは、電縫溶接部において管状体１の両側のエッジ部５を突合せた位置とする。 The welding conditions for the ERW steel pipe according to the present invention are such that the number of oxide inclusions having a particle diameter of 3 μm or more is 2 pieces / mm 2 or less in the cross section of the weld cut out from the ERW steel pipe. The welding conditions can be achieved by setting the atmosphere during welding to an inert gas such as N 2 and setting the oxygen concentration in the gas to 60 ppm or less. In the present invention, the cross section of the welded portion is a position where the edge portions 5 on both sides of the tubular body 1 are abutted in the electro-welded welded portion.

本発明において電縫鋼管の材質は鋼であれば良く特に化学組成は規定しない。主に鉄と鉄鋼材料に用いられる通常の合金元素および不可避的不純物からなる鋼からなる電縫鋼管に本発明を適用することが可能である。   In the present invention, the material of the ERW steel pipe may be steel as long as the chemical composition is not specified. The present invention can be applied to an ERW pipe made of steel mainly composed of ordinary alloy elements and unavoidable impurities used for iron and steel materials.

本発明の効果を実施例を用いて詳細に説明する。種々の組成の鋼帯を供試材とし、上述した図１に示す製造装置により電縫鋼管を製造した。電縫鋼管は溶接部断面における酸化物系介在物の大きさと数が種々変化するように、予め求めておいた複数の条件で溶接を行った。   The effects of the present invention will be described in detail with reference to examples. Using steel strips of various compositions as test materials, ERW steel pipes were manufactured using the manufacturing apparatus shown in FIG. The ERW steel pipe was welded under a plurality of conditions determined in advance so that the size and number of oxide inclusions in the weld cross section varied.

表１に供試材の成分組成を、表２に製造条件と溶接部断面において観察された酸化物系介在物の大きさと個数を示す。   Table 1 shows the component composition of the test material, and Table 2 shows the manufacturing conditions and the size and number of oxide inclusions observed in the weld cross section.

供試材Ｎｏ．１〜８はいずれもSi-Mn鋼で、表２のNo.1〜4は溶接部断面において粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下である本発明例であり、溶接部の耐割れ性に優れる健全な溶接部が得られていた。 Specimen No. Examples 1 to 8 are Si-Mn steels, and Nos. 1 to 4 in Table 2 are examples of the present invention in which the number of oxide inclusions having a particle size of 3 μm or more is 2 / mm 2 or less in the weld cross section. Thus, a sound welded portion excellent in crack resistance of the welded portion was obtained.

一方、表２のNo.5〜8は溶接部断面において粒径が３μm以上の酸化物系介在物の個数が３個／mm2以上の比較例であり、溶接部の耐割れ性に劣っていた。尚、本発明例における酸素濃度は６０ppm以下、比較例における酸素濃度は７９ppm以上であった。 On the other hand, Nos. 5 to 8 in Table 2 are comparative examples in which the number of oxide inclusions having a particle size of 3 μm or more in the cross section of the weld is 3 pieces / mm 2 or more, and the crack resistance of the weld is poor. It was. The oxygen concentration in the present invention example was 60 ppm or less, and the oxygen concentration in the comparative example was 79 ppm or more.

なお、耐割れ性試験は、図3に示すように電縫鋼管をプレスではさみ、管の内側の空間が無くなるまで圧縮し、溶接部に割れが発生した場合を不良、しない場合を良好として行った。     In the crack resistance test, as shown in Fig. 3, the ERW steel pipe is sandwiched with a press and compressed until there is no space inside the pipe. It was.

Figure 2006144109
Figure 2006144109

Figure 2006144109
Figure 2006144109

電縫鋼管の製造装置の一例を示す図。The figure which shows an example of the manufacturing apparatus of an electric resistance steel pipe. EPMAによる測定方法を説明する図。The figure explaining the measuring method by EPMA. 耐割れ性試験方法を説明する図。The figure explaining a cracking resistance test method.

符号の説明Explanation of symbols

１ 管状体
２ シールド装置
３ ワークコイル
４ スクイズロール
５ エッジ部
ａ 溶接点
１１ 電子銃
１２ 試料
１３ 二次電子検出器
１４ 反射電子検出器
１５ 分光結晶
１６ 検出器
２１ 電縫鋼管
２２ 溶接部
２３ プレス DESCRIPTION OF SYMBOLS 1 Tubular body 2 Shielding device 3 Work coil 4 Squeeze roll 5 Edge part a Welding point 11 Electron gun 12 Sample 13 Secondary electron detector 14 Reflected electron detector 15 Spectroscopic crystal 16 Detector 21 ERW steel pipe 22 Welded part 23 Press

Claims (4)

溶接部断面において粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下であることを特徴とする溶接部の耐割れ性に優れる電縫鋼管。 An electric resistance welded steel pipe excellent in crack resistance of a welded portion characterized in that the number of oxide inclusions having a particle size of 3 μm or more in a welded section is 2 / mm 2 or less. 前記酸化物系介在物の個数を電子線マイクロプローブ分析法により求めることを特徴とする請求項１記載の溶接部の耐割れ性に優れる電縫鋼管。 The ERW steel pipe excellent in crack resistance of a welded portion according to claim 1, wherein the number of oxide inclusions is obtained by an electron beam microprobe analysis method. 溶接部断面において粒径が３μm以上の酸化物系介在物の個数が２個／mm2以下となるように溶接条件を調整することを特徴とする溶接部の耐割れ性に優れる電縫鋼管の製造方法。 An ERW steel pipe excellent in crack resistance of a welded portion characterized by adjusting welding conditions so that the number of oxide inclusions having a particle size of 3 μm or more is 2 pieces / mm 2 or less in the welded section. Production method. 前記溶接条件の調整方法として、溶接の際の雰囲気を不活性ガスとし、当該ガス中の酸素濃度を６０ppm以下とすることを特徴とする請求項３に記載の溶接部の耐割れ性に優れる電縫鋼管の製造方法。
The method for adjusting the welding conditions is characterized in that the atmosphere during welding is an inert gas, and the oxygen concentration in the gas is 60 ppm or less. Manufacturing method of sewn steel pipe.
JP2004339533A 2004-11-24 2004-11-24 Electric resistance welded tube having excellent crack resistance in weld zone and its production method Pending JP2006144109A (en)

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Publication number Priority date Publication date Assignee Title
CN104641014A (en) * 2012-09-24 2015-05-20 杰富意钢铁株式会社 Electric-resistance-welded steel pipe exhibiting excellent HIC-resistance and low-temperature toughness at electric-resistance-welded parts, and production method therefor
CN107964637A (en) * 2017-12-13 2018-04-27 武汉钢铁有限公司 A kind of CT100 grades of connecting pipes hot rolled strip and production method

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JPH04238677A (en) * 1991-01-09 1992-08-26 Nippon Steel Corp Mamufacture of electric welded steel tube
JPH0949049A (en) * 1995-08-09 1997-02-18 Nkk Corp Welded steel pipe and its production
JPH11279697A (en) * 1998-03-30 1999-10-12 Nippon Steel Corp Resistance welded steel pipe excellent in workability, and its production
JP2000109949A (en) * 1998-10-06 2000-04-18 Nippon Steel Corp Electric resistance welded tube excellent in workability and its production

Patent Citations (4)

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Publication number Priority date Publication date Assignee Title
JPH04238677A (en) * 1991-01-09 1992-08-26 Nippon Steel Corp Mamufacture of electric welded steel tube
JPH0949049A (en) * 1995-08-09 1997-02-18 Nkk Corp Welded steel pipe and its production
JPH11279697A (en) * 1998-03-30 1999-10-12 Nippon Steel Corp Resistance welded steel pipe excellent in workability, and its production
JP2000109949A (en) * 1998-10-06 2000-04-18 Nippon Steel Corp Electric resistance welded tube excellent in workability and its production

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104641014A (en) * 2012-09-24 2015-05-20 杰富意钢铁株式会社 Electric-resistance-welded steel pipe exhibiting excellent HIC-resistance and low-temperature toughness at electric-resistance-welded parts, and production method therefor
EP2878696A4 (en) * 2012-09-24 2015-11-11 Jfe Steel Corp Electric-resistance-welded steel pipe exhibiting excellent hic resistance and low-temperature toughness at electric-resistance-welded parts, and production method therefor
US9873164B2 (en) 2012-09-24 2018-01-23 Jfe Steel Corporation Electric resistance welded steel pipe or steel tube having excellent HIC resistance and low-temperature toughness in electric resistance welded part, and method for manufacturing the same
CN107964637A (en) * 2017-12-13 2018-04-27 武汉钢铁有限公司 A kind of CT100 grades of connecting pipes hot rolled strip and production method

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