JPH0551648A - Manufacture of electric resistance-welded tube - Google Patents
Manufacture of electric resistance-welded tubeInfo
- Publication number
- JPH0551648A JPH0551648A JP25653591A JP25653591A JPH0551648A JP H0551648 A JPH0551648 A JP H0551648A JP 25653591 A JP25653591 A JP 25653591A JP 25653591 A JP25653591 A JP 25653591A JP H0551648 A JPH0551648 A JP H0551648A
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- cooling
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- electric resistance
- cooling rate
- Prior art date
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、溶接部の低温靭性が優
れた高張力電縫鋼管の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength electric resistance welded steel pipe having excellent low temperature toughness at a welded portion.
【０００２】[0002]
【従来の技術】電縫鋼管の溶接部の靭性を向上させるた
めに、従来一般的に行われていたノルマライジング処理
に代えて、焼鈍後に急冷する方法が例えば特公昭５７−
８８４８号公報あるいは特開昭５９−３５６２９号公報
に開示されている。また焼入れ焼戻しをする方法が例え
ば特開昭５９−４３８２７号公報あるいは特開昭５９−
１５３８３９号公報等に開示されている。さらに焼入れ
に続いて２相域加熱する方法が特開平３−３１４２３号
公報に、焼入れに続いて２相域焼入れした後焼戻しする
方法が特開平２−３０５９２３号公報に開示されてい
る。これらの熱処理はいずれも、基本的には焼入れによ
る結晶粒の微細化を狙ったものであり、微細なフェライ
ト組織を得ることによって靭性の向上を図るものであ
る。このような熱処理方法に対して従来技術では加熱温
度、冷却開始温度及び冷却速度によって熱処理の条件の
みが規定されている。加熱温度に関しては一般的にミル
ラインに直列に配置した誘導加熱装置を用いるためその
出力調整により、また冷却開始温度に関しては冷却開始
位置の調整により容易に実現可能である。しかしながら
焼入れ時の冷却速度に関しては、発明者らの検討によれ
ば、実際的な冷却方法としては管外面側一方向からの冷
却になることから、外面側と内面側で冷却速度の差が生
じてしまい板厚方向に均一な冷却速度は得られず、従っ
て目標とする微細なフェライト組織が板厚方向で均一に
得られないことが明らかになった。2. Description of the Related Art In order to improve the toughness of a welded portion of an electric resistance welded steel pipe, a method of quenching after annealing is used instead of the normalizing treatment which has been generally performed conventionally.
It is disclosed in JP-A-8848 or JP-A-59-35629. A method of quenching and tempering is disclosed, for example, in JP-A-59-43827 or JP-A-59-
It is disclosed in Japanese Patent No. 153839. Further, a method of heating the two-phase region subsequent to the quenching is disclosed in Japanese Patent Application Laid-Open No. 3-31423, and a method of quenching the two-phase region followed by tempering is disclosed in the Japanese Patent Application Laid-Open No. 2-305923. All of these heat treatments are basically aimed at refining crystal grains by quenching, and are intended to improve toughness by obtaining a fine ferrite structure. With respect to such a heat treatment method, in the prior art, only the heat treatment conditions are defined by the heating temperature, the cooling start temperature and the cooling rate. Since the heating temperature is generally an induction heating device arranged in series with the mill line, it can be easily realized by adjusting its output, and the cooling start temperature by adjusting the cooling start position. However, regarding the cooling rate at the time of quenching, according to the study of the inventors, since the cooling is performed from one direction on the outer surface side of the pipe as a practical cooling method, a difference in cooling rate occurs between the outer surface side and the inner surface side. It was found that a uniform cooling rate cannot be obtained in the plate thickness direction, and therefore the target fine ferrite structure cannot be obtained uniformly in the plate thickness direction.
【０００３】従来技術では、たとえ冷却速度を呈示して
いたとしても、その具体的な冷却方法が示されていな
い。一般的には通常の冷却方法では板厚方向に均一な冷
却速度は得られない。特に板厚が１０ｍｍを越える場
合、管内面側の冷却速度を確保するため冷却水量を多く
すれば管外面側の冷却速度が過大となり、管外面側にベ
ーナイト組織が生じて靭性が劣化する。一方管外面側の
冷却速度を抑えるため冷却水量を絞れば、管内面側の冷
却速度が過小となり、組織の微細化が十分に行われず、
やはり靭性が劣化する。このように通常の冷却方法では
板厚方向に冷却速度の差があり、内外面で組織の不均一
が生じ、その結果靭性の劣化を招くという悪影響があ
る。The prior art does not show a specific cooling method, even if the cooling rate is presented. Generally, a normal cooling method cannot obtain a uniform cooling rate in the plate thickness direction. In particular, when the plate thickness exceeds 10 mm, if the cooling water amount is increased in order to secure the cooling rate on the inner surface side of the tube, the cooling rate on the outer surface side of the tube becomes excessively high, and a bainite structure is generated on the outer surface side of the tube to deteriorate the toughness. On the other hand, if the amount of cooling water is reduced in order to suppress the cooling rate on the outer surface of the tube, the cooling rate on the inner surface of the tube will be too small, and the tissue will not be sufficiently refined.
After all, toughness deteriorates. As described above, in the normal cooling method, there is a difference in the cooling rate in the plate thickness direction, which causes nonuniformity of the structure on the inner and outer surfaces, resulting in deterioration of toughness.
【０００４】[0004]
【発明が解決しようとする課題】本発明者らは上記の点
に関して、種々の板厚の電縫管について実験を行い、冷
却速度の均一化について検討を加えた結果、次の（１）
〜（３）の知見を得るに至った。 （１） 管内面側は主に管外面側の温度が下がることに
より熱伝導によって冷却されるため、管内面側では冷却
速度が小さく、また管外面側とは冷却に時間差がある。With respect to the above points, the present inventors have conducted experiments on electric resistance welded pipes of various plate thicknesses and studied the equalization of the cooling rate. As a result, the following (1)
The knowledge of (3) was obtained. (1) The inner surface of the tube is cooled by heat conduction mainly due to the temperature decrease on the outer surface of the tube. Therefore, the cooling rate is low on the inner surface of the tube and there is a time difference in cooling from the outer surface of the tube.
【０００５】（２） Ａｒ1 変態点付近の５００℃より
低い温度域であれば冷却速度が組織に及ぼす影響はほと
んどない。 （３） 上記（１）のことから管外面側が５００℃の時
点でも、肉厚の中央や、管内面側はそれ以上の温度にな
っており、ここで冷却水量を増やして外面温度を速く下
げればその分、肉厚の中央部や管内面側は冷却速度が大
きくなり、管外面側の冷却速度に近づく。(2) In the temperature range below 500 ° C. near the Ar 1 transformation point, the cooling rate has almost no effect on the structure. (3) From the above (1), even at the temperature of 500 ° C on the outer surface of the pipe, the center of the wall thickness and the inner surface of the pipe are at temperatures higher than that, and the amount of cooling water can be increased here to quickly lower the outer surface temperature. As a result, the cooling rate increases at the central portion of the wall thickness and on the pipe inner surface side, and approaches the cooling rate on the pipe outer surface side.
【０００６】本発明は上記知見に基いて完成されたもの
で、電縫管の溶接部の冷却過程に改善を加えることによ
って、溶接部の肉厚方向の組織を適正化し、溶接部の靭
性を向上させることを目的とする。The present invention has been completed based on the above findings. By improving the cooling process of the welded portion of the electric resistance welded pipe, the structure in the thickness direction of the welded portion is optimized and the toughness of the welded portion is improved. The purpose is to improve.
【０００７】[0007]
【課題を解決するための手段】本発明は上記知見に基づ
いてなされたものであって、次の技術手段から構成され
ている。すなわち、連続的に成形した帯鋼を電縫溶接
し、これに引き続いて溶接部をＡｃ3 変態点以上、１０
５０℃以下に加熱し、外表面から強制冷却する過程を含
む熱処理において、前記冷却を溶接部外表面温度が８０
０℃から５００℃〜４００℃までを１０℃／ｓｅｃ以上
かつフェライトが析出する範囲の冷却速度で冷却し、該
溶接部外表面温度が５００℃〜４００℃に到達した時点
で冷却を強化して外表面が２００℃以下になるまで冷却
することを特徴とする電縫鋼管の製造方法である。The present invention has been made on the basis of the above findings, and comprises the following technical means. That is, continuously formed band steel is electric resistance welded, and subsequently, the welded portion is made to have an Ac 3 transformation point or higher, 10 or higher.
In a heat treatment including a process of heating to 50 ° C. or less and forcibly cooling from the outer surface, the cooling is performed at a weld outer surface temperature of 80.
Cooling from 0 ° C to 500 ° C to 400 ° C at a cooling rate of 10 ° C / sec or more and a range in which ferrite precipitates, and strengthen the cooling when the outer surface temperature of the weld reaches 500 ° C to 400 ° C. A method for producing an electric resistance welded steel pipe, which comprises cooling the outer surface to 200 ° C. or lower.
【０００８】この場合に、上記鋼帯の化学組成が、 Ｃ：０．０１〜０．１０重量％、 Ｓｉ：０．５重量％以下、 Ｍｎ：０．５〜２．０重量％、 Ｐ：０．０３０重量％以下、 Ｓ：０．００８重量％以下、 Ｎ：０．０１重量％以下、 Ａｌ：０．０６重量％以下 を含み、かつ Ｎｂ：０．１重量％以下、 Ｖ：０．１重量％以下、 Ｔｉ：０．０５重量％以下 のうちの一種以上を含有し、残部Ｆｅ及び不可避的不純
物よりなる鋼帯とすれば、低温靭性の優れた高張力電縫
鋼管を製造することができ、さらに上記鋼帯の化学組成
がさらに Ｃｒ：０．１〜１．０重量％、 Ｍｏ：０．１〜１．０重量％、 Ｃｕ：０．１〜０．６重量％、 Ｎｉ：０．１〜０．６重量％ のうちの一種以上、又はこれらの代りに、あるいはこれ
らにさらに加えて、 Ｃａ：０．０００５〜０．００５０重量％ を含有すると一層好ましい。In this case, the chemical composition of the steel strip is C: 0.01 to 0.10% by weight, Si: 0.5% by weight or less, Mn: 0.5 to 2.0% by weight, P: 0.030 wt% or less, S: 0.008 wt% or less, N: 0.01 wt% or less, Al: 0.06 wt% or less, and Nb: 0.1 wt% or less, V: 0. 1% by weight or less, Ti: 0.05% by weight or less, a steel strip containing at least one of Fe and unavoidable impurities, and producing a high-strength electric resistance welded steel pipe excellent in low-temperature toughness. In addition, the chemical composition of the steel strip is as follows: Cr: 0.1 to 1.0% by weight, Mo: 0.1 to 1.0% by weight, Cu: 0.1 to 0.6% by weight, Ni: One or more of 0.1 to 0.6% by weight, or instead of these or in addition thereto, Ca: 0 More preferably containing from 0,005 to 0.0050 wt%.
【０００９】また熱処理としては上記２００℃以下まで
の冷却の後に、溶接部を４００℃以上８００℃以下に再
加熱して焼戻すか、又は溶接部をＡｃ1 点以上（Ａｃ3
点−５０℃）以下に再加熱し、６５０℃から２００℃の
温度範囲内まで冷却速度１０℃／ｓｅｃ以上で冷却する
か又は、溶接部をＡｃ1 点以上（Ａｃ3 点−５０℃）以
下に再加熱し、２００℃以下まで冷却速度１０℃／ｓｅ
ｃ以上で冷却し、その後４００℃以上８００℃以下に再
再加熱して焼戻す処理を付加すると一層好ましい低温靭
性の優れた高張力電縫鋼管を製造することができる。As the heat treatment, after cooling to 200 ° C. or less, the welded portion is reheated to 400 ° C. or more and 800 ° C. or less to be tempered, or the welded portion is Ac 1 point or more (Ac 3
Reheat to less than -50 ° C) and cool it within a temperature range of 650 ° C to 200 ° C at a cooling rate of 10 ° C / sec or more, or weld the Ac 1 point or more (Ac 3 point-50 ° C) or less. Reheated to 200 ℃, cooling rate 10 ℃ / se
A high-strength electric resistance welded steel pipe having excellent low-temperature toughness can be manufactured by cooling at c or higher, and then reheating to 400 ° C. or higher and 800 ° C. or lower and tempering.
【００１０】本発明において「冷却を強化する」とは、
抜熱速度を高めることをいい、冷却水などの冷却媒体量
を増加することを指称する。In the present invention, "intensify cooling" means
It means increasing the heat removal rate, and indicates increasing the amount of cooling medium such as cooling water.
【００１１】[0011]
【作用】以下この発明について作用と共に詳細に説明す
る。本発明は電縫管の溶接部を焼入れすることを含む熱
処理において、焼入れの際の冷却を２段に分け、前段を
緩冷、後段を急冷とする制御冷却を行い、板厚方向の冷
却速度を均一化することにより、溶接部低温靭性の向上
を達成するものである。The operation of the present invention will be described in detail below. The present invention, in a heat treatment including quenching a welded portion of an electric resistance welded pipe, cooling during quenching is divided into two stages, control cooling is performed such that the first stage is slow cooling and the second stage is rapid cooling. By homogenizing the, the low temperature toughness of the welded part is improved.
【００１２】以下この発明について詳細に説明する。ま
ず素材成分の限定理由について説明する。Ｃは強度を確
保するための元素であるが、含有量が増えると靭性が劣
化するため０．０１〜０．１０重量％とした。Ｓｉも強
度確保のための必要元素であるが、０．５重量％を超え
ると溶接部にペネトレータが発生しやすくなり靭性が劣
化するため０．５重量％以下規定とした。The present invention will be described in detail below. First, the reasons for limiting the material components will be described. C is an element for ensuring strength, but if the content increases, the toughness deteriorates, so 0.01 to 0.10% by weight was set. Si is also a necessary element for securing strength, but if it exceeds 0.5% by weight, penetrators are easily generated in the welded portion and the toughness deteriorates, so 0.5% by weight or less is specified.
【００１３】Ｍｎも強度を保つための必要元素である
が、０．５重量％未満では必要強度が得られず、２．０
重量％を超えるとＳｉと同様に溶接部にペネトレータが
発生しやすくなるため０．５〜２．０重量％とした。Ｐ
は偏析を生じて靭性を劣化させる元素なので低い方が望
ましく、０．０３０重量％以下とした。さらに耐サワー
性を考慮する場合には、Ｐは０．０１０重量％以下が望
ましい。Mn is also a necessary element for maintaining the strength, but if it is less than 0.5% by weight, the necessary strength cannot be obtained, and 2.0
If it exceeds 5% by weight, a penetrator is likely to be generated in the welded portion like Si, so the content is set to 0.5 to 2.0% by weight. P
Is an element that causes segregation and deteriorates toughness, so a lower content is desirable and the content was made 0.030% by weight or less. Further, in consideration of sour resistance, P is preferably 0.010% by weight or less.
【００１４】ＳはＭｎＳの介在物が靭性に悪影響を及ぼ
すため低い方が望ましく、０．００８重量％以下とし
た。さらにＭｎＳはＨＩＣの起点となるので、Ｓは耐サ
ワー性確保の点からは極力低く押さえて、０．００３重
量％以下が望ましい。Ｎはサイジング工程で加工を受け
た際、歪時効による靭性劣化の原因となるため低いほう
がよく、０．０１重量％以下とした。Since MnS inclusions adversely affect the toughness, it is desirable that the content of S be as low as 0.008% by weight or less. Further, since MnS becomes a starting point of HIC, S is preferably kept as low as possible from the viewpoint of ensuring sour resistance, and is preferably 0.003% by weight or less. When N is processed in the sizing step, it causes toughness deterioration due to strain aging, so N is preferably low and is set to 0.01% by weight or less.
【００１５】ＡｌはＡｌＮとしてオーステナイト粒を細
粒化する効果が大きいが、０．０６重量％を超えると介
在物が増加し欠陥の原因となるため０．０６重量％以下
とした。Ｎｂ，Ｖ，Ｔｉについては、強度確保及び結晶
粒微細化のために必要な元素であり、Ｎｂ，Ｖは０．１
重量％以下、Ｔｉは０．０５重量％以下とした。Al has a great effect as AlN for refining austenite grains, but if it exceeds 0.06% by weight, inclusions increase and cause defects, so the content was made 0.06% by weight or less. Nb, V and Ti are elements necessary for securing strength and refining crystal grains, and Nb and V are 0.1
Weight% or less and Ti were 0.05 weight% or less.
【００１６】Ｃｒ，Ｍｏ，Ｃｕ，Ｎｉについては強度、
靭性あるいは耐食性を改善する元素であり、それぞれの
成分の限定理由は以下の通りである。Ｃｒ，Ｍｏは強度
の向上に効果があるが、０．１０重量％未満では効果が
得られず、１．０重量％を超えると靭性に悪影響を与え
るので０．１０〜１．０重量％とした。For Cr, Mo, Cu and Ni, strength,
It is an element that improves toughness or corrosion resistance, and the reasons for limiting each component are as follows. Cr and Mo are effective in improving the strength, but if less than 0.10% by weight, no effect is obtained, and if over 1.0% by weight, the toughness is adversely affected. did.
【００１７】Ｃｕは強度及び耐食性の向上に効果がある
が、０．１重量％未満ではその効果が少なく、０．６重
量％を超えると熱間加工性を損なうので０．１〜０．６
重量％とした。Ｎｉは強度、靭性の向上ならびに耐食性
の向上に効果があり、またＣｕによる熱間加工性の低下
を防ぐためにも必要な元素であるが、０．１重量％未満
では効果がなく、０．６重量％を超えると硫化物応力腐
食が発生しやすくなるため０．１〜０．６重量％とし
た。Cu has the effect of improving strength and corrosion resistance, but if it is less than 0.1% by weight, its effect is small, and if it exceeds 0.6% by weight, hot workability is impaired.
It was made into the weight%. Ni is an element that is effective in improving strength and toughness and corrosion resistance, and is also necessary for preventing the deterioration of hot workability due to Cu. If the content exceeds 10% by weight, sulfide stress corrosion tends to occur, so the content was set to 0.1 to 0.6% by weight.
【００１８】Ｃａは硫化物系介在物を球状化し、靭性及
び耐ＨＩＣ性を向上させる元素であり、その効果を得る
ためには０．０００５重量％以上必要であるが、０．０
０５０重量％を超えるとＣａ系の介在物が増加し、靭性
及び耐ＨＩＣ性を低下させるため０．０００５〜０．０
０５０重量％とした。次に、熱処理条件について説明す
る。Ca is an element that makes the sulfide-based inclusions spherical and improves toughness and HIC resistance. To obtain the effect, 0.0005% by weight or more is necessary, but 0.0
If it exceeds 050% by weight, Ca-based inclusions increase and the toughness and HIC resistance are lowered, so 0.0005-0.0
It was 050% by weight. Next, heat treatment conditions will be described.
【００１９】加熱温度をＡｃ3 以上、１０５０℃以下の
範囲に限定したのは、電縫溶接直後の靭性の劣化した急
冷組織を消去するためＡｃ3 変態点以上に加熱してオー
ステナイト組織にする必要があるが、誘導加熱などによ
る外面側一方向からの急速加熱の場合、加熱温度がＡc3
未満では内面側まで十分焼きならしができず、一方加熱
温度が１０５０℃を超えると結晶粒が粗大化し靭性が劣
化するためである。The heating temperature is limited to a range from Ac 3 to 1050 ° C. in order to eliminate the quenched structure with deteriorated toughness immediately after electric resistance welding and to heat it to the Ac 3 transformation point or higher to form an austenite structure. However, in the case of rapid heating from one direction on the outer surface due to induction heating, the heating temperature is A c3
This is because if the temperature is less than the above range, normalizing cannot be sufficiently performed to the inner surface side, while if the heating temperature exceeds 1050 ° C., the crystal grains become coarse and the toughness deteriorates.
【００２０】その後の冷却条件について、Ａc3変態点以
上の温度から冷却を開始し、溶接部外表面温度が８００
℃から５００〜４００℃までを、１０℃／ｓｅｃ以上か
つフェライトが析出する範囲の冷却速度で冷却すること
としたのは、冷却開始温度がＡc3変態点より低くなると
組織の整流均一化が行われず急冷の効果がなくなるから
であり、また、冷却速度が１０℃／ｓｅｃより遅いと結
晶粒が粗大化してしまい、靭性が劣化するためであり、
また冷却速度が例えば図８に示すようなＣＣＴ曲線（連
続冷却変態曲線）で決るフェライトが析出する範囲の冷
却速度を越えると外面側がベーナイトあるいはマルテン
サイトの脆化組織となり好ましくないためである。With respect to the subsequent cooling conditions, cooling is started from a temperature above the A c3 transformation point, and the outer surface temperature of the weld is 800
It was decided to cool from 500 to 400 ° C. at a cooling rate of 10 ° C./sec or more and a range in which ferrite is precipitated, because the rectification and homogenization of the structure is performed when the cooling start temperature becomes lower than the Ac 3 transformation point. If the cooling rate is slower than 10 ° C./sec, the crystal grains become coarse and the toughness deteriorates.
Also, if the cooling rate exceeds the cooling rate in the range where ferrite precipitates, which is determined by the CCT curve (continuous cooling transformation curve) as shown in FIG. 8, for example, the outer surface side becomes unfavorably a brittle structure of bainite or martensite.
【００２１】このような冷却を外面側が５００〜４００
℃に到達するまで実施するのは、この温度になると、管
の外面側が変態をほぼ完了するからである。５００℃を
越える温度で冷却を強化すると、脆化組織が混在し靭性
が劣化する。一方４００℃未満まで冷却すると管の外面
側以外の部分も変態を完了してしまいその後冷却を強化
しても細粒化の効果がなくなる。Such cooling is performed on the outer surface side by 500 to 400.
The process is carried out until the temperature reaches 0 ° C., because at this temperature, the transformation of the outer surface side of the pipe is almost completed. If the cooling is strengthened at a temperature exceeding 500 ° C, the embrittlement structure is mixed and the toughness deteriorates. On the other hand, if it is cooled to less than 400 ° C., the transformation of parts other than the outer surface side of the tube is completed, and even if the cooling is strengthened thereafter, the effect of grain refining is lost.
【００２２】その後、冷却を強化した状態で管外表面側
が２００℃以下になるまで冷却するのは、板厚方向の内
外面温度差を考慮した上で内面側を十分に変態完了させ
るためである。次に２００℃以下まで冷却した後に際加
熱焼入れ焼戻しする場合について説明する。Thereafter, the cooling is strengthened until the outer surface of the pipe is cooled down to 200 ° C. or lower in order to sufficiently complete the transformation of the inner surface in consideration of the temperature difference between the inner surface and the outer surface in the plate thickness direction. .. Next, a case where the material is cooled to 200 ° C. or lower and then hot-quenched and tempered will be described.
【００２３】再加熱温度を４００〜８００℃の範囲に限
定したのは、４００℃未満では焼戻し効果が得られず、
一方８００℃を超えると結晶粒が粗大化して直前の加熱
急冷処理によって得た微細組織が消失し靭性が劣化する
ためである。また、焼入れに続いて２相域加熱する場
合、再加熱温度をＡｃ1 点以上、（Ａｃ3 点−５０℃）
以下の範囲に限定したのは、上記の処理によって得られ
た微細フェライト組織をさらに微細化するべく、オース
テナイト・フェライト２相域に加熱するためである。そ
の後の冷却条件で、６５０℃から２００℃の温度範囲内
までを１０℃／ｓｅｃ以上で冷却しその後空冷すること
にしたのは、６５０℃を超える温度で冷却を停止すると
組織が粗大化して靭性が劣化し、一方２００℃未満まで
該冷却を実施するとマルテンサイト等の脆化組織が生成
して靭性が劣化するためであり、またこの冷却速度が１
０℃未満の場合、十分に微細な組織が得られないためで
ある。The reason for limiting the reheating temperature to the range of 400 to 800 ° C. is that the tempering effect cannot be obtained below 400 ° C.
On the other hand, if the temperature exceeds 800 ° C., the crystal grains become coarse and the fine structure obtained by the immediately preceding heating and quenching treatment disappears, and the toughness deteriorates. Also, when heating in the two-phase region following quenching, the reheating temperature is Ac 1 point or higher (Ac 3 points-50 ° C).
The reason for limiting the range to the following is to heat the austenite-ferrite two-phase region in order to further refine the fine ferrite structure obtained by the above treatment. Under the subsequent cooling conditions, the temperature range of 650 ° C to 200 ° C was cooled at 10 ° C / sec or more and then air-cooled. The reason is that when cooling is stopped at a temperature higher than 650 ° C, the structure becomes coarse and the toughness increases. On the other hand, when the cooling is carried out to less than 200 ° C., an embrittlement structure such as martensite is generated and the toughness deteriorates, and the cooling rate is 1
This is because if the temperature is lower than 0 ° C, a sufficiently fine structure cannot be obtained.
【００２４】さらに、焼入れに続いて２相焼入れした後
焼戻しする場合、再加熱温度をＡｃ 1 点以上、（Ａｃ3
点−５０℃）以下の範囲に限定したのは、上記の処理に
よって得られた微細フェライト組織をさらに微細化する
べく、オーステナイト・フェライト２相域に加熱するた
めである。その後の冷却条件で、２００℃以下の温度ま
でを１０℃／ｓｅｃ以上で冷却することにしたのは、２
００℃を超える温度で該冷却を停止すると組織が十分細
粒化されず靭性が劣化するためであり、また該冷却の冷
却速度が１０℃未満の場合、十分に微細な組織が得られ
ないためである。さらに、再再加熱温度を４００〜８０
０℃の範囲に限定したのは、４００℃未満では焼戻し効
果が得られず、一方８００℃を超えるとフェライト結晶
粒が粗大化して靭性が劣化するためである。After further quenching, followed by two-phase quenching
When tempering, set the reheating temperature to Ac 1 Above the point, (Ac3
The point below -50 ° C) is limited to the above treatment.
Further refine the obtained fine ferrite structure
In order to heat the austenite-ferrite two-phase region
It is. Under subsequent cooling conditions, temperatures up to 200 ° C
It was decided that the cooling at 10 ℃ / sec or more is 2
If the cooling is stopped at a temperature above 00 ° C, the tissue will become fine enough.
This is because the toughness deteriorates without being granulated.
If the rejection rate is less than 10 ° C, a sufficiently fine structure can be obtained.
Because there is no. Furthermore, the reheating temperature is set to 400 to 80.
The tempering effect is limited to less than 400 ° C in the range of 0 ° C.
No fruit is obtained, while ferrite crystals are produced when the temperature exceeds 800 ° C.
This is because the grains become coarse and the toughness deteriorates.
【００２５】[0025]
【実施例】本発明を実施する電縫管製造設備の概略を図
１、図２に示す。連続的に成形された鋼帯１のエッジを
溶接電極３で加熱し、スクイズロール４で加圧、接合
し、電縫溶接部２をもつ電縫管１１を製造する。この電
縫溶接部２を誘導加熱装置５，６によって所定温度まで
加熱した後、水冷装置９により外面側から所定の方法で
所定温度まで冷却する。さらに、その後焼入れ焼戻しを
施す場合は、図１の装置を用い誘導加熱装置７で再加熱
し、焼戻し処理を施す。また焼入れに続いて２相域加熱
する場合は、誘導加熱装置７で再加熱し、水冷装置１０
で冷却する。さらに、焼入れに続いて２相域焼入れした
後焼戻しする場合は、誘導加熱装置７で再加熱し、水冷
装置１０で冷却し、その後再び誘導加熱装置８で加熱し
て焼戻し処理を施す。EXAMPLE An outline of an electric resistance welded pipe manufacturing facility for carrying out the present invention is shown in FIGS. The edge of the continuously formed steel strip 1 is heated by the welding electrode 3, pressed and joined by the squeeze roll 4, and the electric resistance welded pipe 11 having the electric resistance welded portion 2 is manufactured. After the electric resistance welded portion 2 is heated to a predetermined temperature by the induction heating devices 5 and 6, it is cooled from the outer surface side to a predetermined temperature by a predetermined method by the water cooling device 9. Furthermore, when quenching and tempering is applied thereafter, the induction heating device 7 is used to reheat the device of FIG. 1 to perform tempering. When heating in the two-phase region following quenching, the induction heating device 7 reheats the water and the water cooling device 10
Cool with. Further, when quenching is performed after quenching in the two-phase region, the material is reheated by the induction heating device 7, cooled by the water cooling device 10, and then heated again by the induction heating device 8 to perform tempering treatment.
【００２６】次に本発明の実施例を板厚１２．７ｍｍの
場合について説明する。図４に一例として水量密度１１
００リットル／ｍｉｎ・ｍ2 で一定の場合の管内外面の
冷却曲線を示した。この場合管外面の冷却速度は１２５
℃／ｓｅｃ、管内面の冷却速度は３０℃／ｓｅｃで、管
外面の冷却速度はフェライトが析出する限界冷却速度を
越えており、また管の内外面の冷却速度の差が９５℃／
ｓｅｃと非常に大きい。Next, an embodiment of the present invention will be described for the case where the plate thickness is 12.7 mm. As an example, in FIG.
The cooling curves of the inner and outer surfaces of the tube when the rate was constant at 00 liter / min · m 2 are shown. In this case, the cooling rate of the outer surface of the pipe is 125
C./sec, the cooling rate on the inner surface of the tube was 30.degree. C./sec, the cooling rate on the outer surface of the tube exceeded the critical cooling rate at which ferrite was precipitated, and the difference between the cooling rates on the inner and outer surfaces of the tube was 95.degree.
It is very large at sec.
【００２７】そこで図３に示すように、まず冷却の初期
では水量密度４００リットル／ｍｉｎ・ｍ2 で管外面側
の冷却速度を臨界冷却速度以下の４０℃／ｓｅｃ程度と
し、管外面の温度が５００℃となる時点で、水量密度を
２０００リットル／ｍｉｎ・ｍ2 に上げて冷却を強化す
れば、管外面側の温度がより早く下がる。この時点で肉
厚の中央部、管内面側の温度はまだ５００℃以上であ
る。したがって、熱伝導による冷却で肉厚の中央部、管
内面側の冷却速度が上がり、５００℃までの管内面側の
冷却速度が２５℃／ｓｅｃ程度となる。従って、このよ
うな冷却パターンで冷却を行えば、８００℃〜５００℃
の冷却速度は管外面側が４０℃／ｓｅｃ、管内面側が２
５℃／ｓｅｃとなり、管内外面の冷却速度の差が１５℃
／ｓｅｃで通常の場合に比べて著しく小さくなる。Therefore, as shown in FIG. 3, in the initial stage of cooling, the cooling rate on the outer surface of the pipe is set to about 40 ° C./sec which is less than the critical cooling rate at a water density of 400 liter / min · m 2 , and the temperature on the outer surface of the pipe is When the temperature reaches 500 ° C., if the water volume density is increased to 2000 liters / min · m 2 to strengthen the cooling, the temperature on the outer surface side of the pipe will decrease more quickly. At this point, the temperature at the central portion of the wall thickness and the inner surface of the pipe is still 500 ° C. or higher. Therefore, the cooling rate at the central portion of the wall thickness and the inner surface of the tube is increased by cooling by heat conduction, and the cooling rate on the inner surface of the tube up to 500 ° C. is about 25 ° C./sec. Therefore, if cooling is performed in such a cooling pattern, 800 ° C to 500 ° C
The cooling rate is 40 ° C / sec on the outer surface of the tube and 2 on the inner surface of the tube.
5 ° C / sec, the difference in cooling rate between the inside and outside of the pipe is 15 ° C
/ Sec is significantly smaller than in the normal case.
【００２８】以上で述べたような冷却パターンにより、
管の内外面の冷却速度の差が減少し板厚方向の冷却速度
が均一化される。ここで冷却を強化するパターンとして
図３に示した２段ステップ状に水量を増やすパターンの
他、例えば図５に示すように多段ステップ状に水量を増
やすパターン、あるいは図６に示すように連続的に水量
を増やすパターンがあり、これらのいずれのパターンと
してもよい。By the cooling pattern as described above,
The difference in cooling rate between the inner and outer surfaces of the tube is reduced, and the cooling rate in the plate thickness direction is made uniform. Here, as a pattern for strengthening cooling, in addition to the pattern of increasing the water amount in a two-step manner shown in FIG. 3, for example, a pattern of increasing the water amount in a multi-step manner as shown in FIG. 5 or continuously as shown in FIG. There is a pattern for increasing the amount of water, and any of these patterns may be used.
【００２９】発明者らの研究によれば、図７に示すよう
に板厚方向の冷却速度の均一化により組織の均一性が向
上し、特に板厚方向の冷却速度の差を２０℃／ｓｅｃ以
下にすれば靭性が非常に向上することが判明している。
表１、表２、表３に示される化学成分組成の鋼を用い、
図１に概略を示す装置で電縫溶接を行い、次いで表４、
表５、表６、表７、表８、表９、表１０、表１１に示す
各条件で熱処理を施し、外径５０８ｍｍφ、肉厚１２．
７ｍｍの電縫鋼管を製造した。また表１２に示す化学成
分、外径、肉厚の電縫鋼管を表１３に示す条件で熱処理
を行った。なお、表４、表５、表６、表７、表８、表１
０には合せてフェライトが析出する臨界冷却速度も示し
てある。ここで図１の水冷装置９の下流側に配設されて
いる誘導加熱装置７，８や水冷装置１０は熱処理の種類
に応じて使い分けた。表４、５は、１回の強制冷却の場
合の例を示し、表６、７；表１３は、強制冷却後２回目
の加熱冷却を施した場合の例を示し、表８、９；表１
０、１１はさらに３回目の加熱冷却を施した例を示した
ものである。According to the research conducted by the inventors, as shown in FIG. 7, the uniformity of the structure is improved by making the cooling rate uniform in the plate thickness direction. Particularly, the difference in the cooling rate in the plate thickness direction is 20 ° C./sec. It has been found that the toughness is significantly improved by the following.
Using steel having the chemical composition shown in Table 1, Table 2 and Table 3,
Electric resistance welding was performed with the apparatus outlined in FIG.
Heat treatment was performed under the conditions shown in Table 5, Table 6, Table 7, Table 8, Table 9, Table 10, and Table 11 to obtain an outer diameter of 508 mmφ and a wall thickness of 12.
A 7 mm electric resistance welded steel pipe was manufactured. Further, the electric resistance welded steel pipe having the chemical composition, outer diameter and wall thickness shown in Table 12 was heat-treated under the conditions shown in Table 13. In addition, Table 4, Table 5, Table 6, Table 7, Table 8, and Table 1
In addition, the critical cooling rate at which ferrite is precipitated is also shown in 0. Here, the induction heating devices 7 and 8 and the water cooling device 10 arranged on the downstream side of the water cooling device 9 in FIG. 1 were used properly according to the type of heat treatment. Tables 4 and 5 show examples in the case of one forced cooling, Tables 6 and 7; Table 13 show examples in the case of performing the second heating and cooling after the forced cooling, and Tables 8 and 9; 1
Nos. 0 and 11 show examples in which the third heating and cooling were performed.
【００３０】次に、このようにして製造された電縫鋼管
の溶接部から１０ｍｍ×１０ｍｍ、２Ｖノッチのシャル
ピー試験片を切り出して衝撃試験を実施し、シャルピー
遷移曲線から破面遷移温度を調査した。表４、表５、表
６、表７、表９、表１１、表１３に溶接部の熱処理条件
とともに破面遷移温度を示す。本発明例では管外面側、
管内面側の冷却速度はいずれも臨界冷却速度以下であ
り、かつ１０℃／ｓｅｃ以上で、本発明の条件を満たし
ている。表４、表５、表６、表７、表１２の結果から明
らかなように、本発明法により従来法に比べて溶接部低
温靭性が非常に優れた電縫鋼管の製造が可能である。Next, a Charpy test piece of 10 mm × 10 mm, 2V notch was cut out from the welded portion of the electric resistance welded steel pipe manufactured in this way, an impact test was carried out, and the fracture surface transition temperature was investigated from the Charpy transition curve. . Table 4, Table 5, Table 6, Table 7, Table 9, Table 11, and Table 13 show the fracture surface transition temperature together with the heat treatment conditions of the welded portion. In the present invention example, the pipe outer surface side,
All of the cooling rates on the inner surface of the tube are below the critical cooling rate and above 10 ° C./sec, which satisfies the conditions of the present invention. As is clear from the results of Table 4, Table 5, Table 6, Table 7, and Table 12, the method of the present invention makes it possible to manufacture an electric resistance welded steel pipe having excellent low-temperature toughness at the welded portion as compared with the conventional method.
【００３１】[0031]
【表１】 [Table 1]
【００３２】[0032]
【表２】 [Table 2]
【００３３】[0033]
【表３】 [Table 3]
【００３４】[0034]
【表４】 [Table 4]
【００３５】[0035]
【表５】 [Table 5]
【００３６】[0036]
【表６】 [Table 6]
【００３７】[0037]
【表７】 [Table 7]
【００３８】[0038]
【表８】 [Table 8]
【００３９】[0039]
【表９】 [Table 9]
【００４０】[0040]
【表１０】 [Table 10]
【００４１】[0041]
【表１１】 [Table 11]
【００４２】[0042]
【表１２】 [Table 12]
【００４３】[0043]
【表１３】 [Table 13]
【００４４】[0044]
【発明の効果】本発明によれば、電縫管の溶接部の管厚
方向の組織の均一化を図ることができ、溶接部の靭性を
向上させることができる。According to the present invention, the structure of the welded portion of the electric resistance welded pipe in the pipe thickness direction can be made uniform, and the toughness of the welded portion can be improved.
【図１】本発明を実施する電縫鋼管製造設備の概略図で
ある。FIG. 1 is a schematic view of an electric resistance welded steel pipe manufacturing facility for carrying out the present invention.
【図２】本発明を実施する電縫鋼管製造設備の概略図で
ある。FIG. 2 is a schematic diagram of an electric resistance welded pipe manufacturing facility for carrying out the present invention.
【図３】本発明法の冷却パターンと内外面の冷却カーブ
である。FIG. 3 is a cooling pattern of the method of the present invention and a cooling curve of inner and outer surfaces.
【図４】従来法の冷却パターンと内外面の冷却カーブで
ある。FIG. 4 is a cooling pattern of a conventional method and a cooling curve of inner and outer surfaces.
【図５】本発明に含まれる別の冷却パターンを示す図で
ある。FIG. 5 is a diagram showing another cooling pattern included in the present invention.
【図６】本発明に含まれる別の冷却パターンを示す図で
ある。FIG. 6 is a diagram showing another cooling pattern included in the present invention.
【図７】本発明の効果を示すグラフである。FIG. 7 is a graph showing the effect of the present invention.
【図８】ＣＣＴ曲線の例を示す図である。FIG. 8 is a diagram showing an example of a CCT curve.
１ 鋼帯 ２ 電縫溶
接部 ３ 溶接電極 ４ スクイ
ズロール ５，６，７，８ 誘導加熱装置 ９，１０
水冷装置 １１ 電縫管1 Steel Strip 2 ERW Welding Part 3 Welding Electrode 4 Squeeze Roll 5, 6, 7, 8 Induction Heating Device 9, 10
Water cooling device 11 ERW pipe
Claims (7)
れに引き続いて溶接部をＡｃ3 変態点以上、１０５０℃
以下に加熱し、外表面から強制冷却する過程を含む熱処
理において、前記冷却を溶接部外表面温度が８００℃か
ら５００℃〜４００℃までを１０℃／ｓｅｃ以上かつフ
ェライトが析出する範囲の冷却速度で冷却し、該溶接部
外表面温度が５００℃〜４００℃に到達した時点で冷却
を強化して外表面が２００℃以下になるまで冷却するこ
とを特徴とする電縫鋼管の製造方法。1. A continuously formed strip steel is electric resistance welded, and subsequently, the welded portion is at or above the Ac 3 transformation point, 1050 ° C.
In the heat treatment including the process of heating to the following and forcibly cooling from the outer surface, the cooling is performed at a cooling rate in the range where the outer surface temperature of the welded portion is 800 ° C to 500 ° C to 400 ° C at 10 ° C / sec or more and ferrite is precipitated. The method for producing an electric resistance welded steel pipe, comprising: cooling at a temperature of 500 ° C. to 400 ° C. and cooling until the outer surface becomes 200 ° C. or lower.
物よりなる鋼帯であることを特徴とする低温靭性の優れ
た高張力電縫鋼管の製造方法。2. The steel strip according to claim 1, wherein C: 0.01 to 0.10% by weight, Si: 0.5% by weight or less, Mn: 0.5 to 2.0% by weight, P: 0. 0.030% by weight or less, S: 0.008% by weight or less, N: 0.01% by weight or less, Al: 0.06% by weight or less, and Nb: 0.1% by weight or less, V: 0.1 Manufacture of a high-strength electric resistance welded steel pipe having excellent low temperature toughness, characterized in that it is a steel strip containing at least one of Ti: 0.05 wt% or less and the balance Fe and unavoidable impurities. Method.
る低温靭性の優れた高張力電縫鋼管の製造方法。3. The steel strip according to claim 2, further comprising: Cr: 0.1 to 1.0% by weight, Mo: 0.1 to 1.0% by weight, Cu: 0.1 to 0.6% by weight, A method for producing a high-strength electric resistance welded steel pipe having excellent low-temperature toughness, which is a steel strip containing one or more of Ni: 0.1 to 0.6% by weight.
た高張力電縫鋼管の製造方法。4. A high-strength ERW steel pipe having excellent low-temperature toughness, characterized in that the steel strip according to claim 2 or 3 is a steel strip further containing Ca: 0.0005 to 0.0050% by weight. Production method.
部を４００℃以上８００℃以下に再加熱して焼戻すこと
を特徴とする請求項１、２、３又は４記載の低温靭性の
優れた高張力電縫鋼管の製造方法。5. The low temperature toughness according to claim 1, wherein the welded portion is reheated to 400 ° C. or more and 800 ° C. or less and tempered after being cooled to 200 ° C. or less. An excellent method for manufacturing high-strength ERW steel pipe.
Ａｃ1 点以上、（Ａｃ3 点−５０℃）以下に再加熱後、
６５０℃から２００℃の温度範囲内まで冷却速度１０℃
／ｓｅｃ以上で冷却することを特徴とする請求項１、
２、３又は４記載の低温靭性の優れた高張力電縫鋼管の
製造方法。6. After cooling to 200 ° C. or lower, the welded portion is reheated to Ac 1 point or higher and (Ac 3 point −50 ° C.) or lower,
Cooling rate of 10 ℃ from 650 ℃ to 200 ℃
The cooling is performed at a speed of not less than 1 sec / sec.
The method for producing a high-strength electric resistance welded steel pipe excellent in low temperature toughness according to 2, 3, or 4.
Ａｃ1 点以上（Ａｃ 3 点−５０℃）以下に再加熱し、再
び２００℃以下まで冷却速度１０℃／ｓｅｃ以上で冷却
し、その後４００℃以上８００℃以下に加熱して焼戻す
ことを特徴とする請求項１、２、３又は４記載の低温靭
性の優れた高張力電縫鋼管の製造方法。7. The welded part is cooled after cooling to 200 ° C. or lower.
Ac1 Above the point (Ac 3 Reheat to below -50 ℃)
And cooling rate up to 200 ° C at a cooling rate of 10 ° C / sec or more
Then heat to 400 ℃ or more and 800 ℃ or less to temper
5. The low temperature toughness according to claim 1, 2, 3 or 4.
A method of manufacturing a high-strength ERW steel pipe with excellent properties.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25653591A JPH0551648A (en) | 1991-06-10 | 1991-10-03 | Manufacture of electric resistance-welded tube |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3-136911 | 1991-06-10 | ||
| JP13691191 | 1991-06-10 | ||
| JP25653591A JPH0551648A (en) | 1991-06-10 | 1991-10-03 | Manufacture of electric resistance-welded tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0551648A true JPH0551648A (en) | 1993-03-02 |
Family
ID=26470374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25653591A Pending JPH0551648A (en) | 1991-06-10 | 1991-10-03 | Manufacture of electric resistance-welded tube |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0551648A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007301574A (en) * | 2006-05-09 | 2007-11-22 | Nakajima Steel Pipe Co Ltd | Steel tube manufacturing method, and steel tube manufacturing facility |
| WO2010002269A1 (en) * | 2008-06-30 | 2010-01-07 | Efd Induction As | In-line weld seam heat treatment method and apparatus with internal selective heating of the welded joint |
| FR2991213A1 (en) * | 2012-06-05 | 2013-12-06 | Alstom Hydro France | PROCESS FOR WELDING TWO EDGES OF ONE OR MORE STEEL PARTS TO ONE ANOTHER AND FORCED DRIVEN OBTAINED BY SUCH A METHOD |
| KR101979019B1 (en) * | 2018-09-18 | 2019-05-15 | 장근수 | Alloy pipe cooling and transporting apparatus |
| WO2021106577A1 (en) | 2019-11-29 | 2021-06-03 | Ｊｆｅスチール株式会社 | Electric resistance welded steel pipe, and method for manufacturing same |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62158822A (en) * | 1986-01-07 | 1987-07-14 | Nippon Steel Corp | Manufacture of high strength steel tube having low hardness and yield ratio |
| JPH02305923A (en) * | 1989-05-18 | 1990-12-19 | Sumitomo Metal Ind Ltd | Production of high tensile electric welded steel pipe having excellent low-temp. toughness |
| JPH0331423A (en) * | 1989-06-29 | 1991-02-12 | Sumitomo Metal Ind Ltd | Production of high tensile electric welded steel tube having excellent low temp. toughness |
| JPH0364415A (en) * | 1989-07-31 | 1991-03-19 | Nippon Steel Corp | Production of high-toughness seamless low alloy steel tube |
-
1991
- 1991-10-03 JP JP25653591A patent/JPH0551648A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62158822A (en) * | 1986-01-07 | 1987-07-14 | Nippon Steel Corp | Manufacture of high strength steel tube having low hardness and yield ratio |
| JPH02305923A (en) * | 1989-05-18 | 1990-12-19 | Sumitomo Metal Ind Ltd | Production of high tensile electric welded steel pipe having excellent low-temp. toughness |
| JPH0331423A (en) * | 1989-06-29 | 1991-02-12 | Sumitomo Metal Ind Ltd | Production of high tensile electric welded steel tube having excellent low temp. toughness |
| JPH0364415A (en) * | 1989-07-31 | 1991-03-19 | Nippon Steel Corp | Production of high-toughness seamless low alloy steel tube |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007301574A (en) * | 2006-05-09 | 2007-11-22 | Nakajima Steel Pipe Co Ltd | Steel tube manufacturing method, and steel tube manufacturing facility |
| WO2010002269A1 (en) * | 2008-06-30 | 2010-01-07 | Efd Induction As | In-line weld seam heat treatment method and apparatus with internal selective heating of the welded joint |
| FR2991213A1 (en) * | 2012-06-05 | 2013-12-06 | Alstom Hydro France | PROCESS FOR WELDING TWO EDGES OF ONE OR MORE STEEL PARTS TO ONE ANOTHER AND FORCED DRIVEN OBTAINED BY SUCH A METHOD |
| WO2013182582A1 (en) * | 2012-06-05 | 2013-12-12 | Alstom Renewable Technologies | Method for welding two edges of one or more steel parts to each other including a heat treatment step after the welding step: penstock obtained with such a method |
| CN104520060A (en) * | 2012-06-05 | 2015-04-15 | 阿尔斯通再生能源技术公司 | Method for welding two edges of one or more steel parts to each other including heat treatment step after the welding step: penstock obtained with such method |
| KR101979019B1 (en) * | 2018-09-18 | 2019-05-15 | 장근수 | Alloy pipe cooling and transporting apparatus |
| WO2021106577A1 (en) | 2019-11-29 | 2021-06-03 | Ｊｆｅスチール株式会社 | Electric resistance welded steel pipe, and method for manufacturing same |
| KR20220084380A (en) | 2019-11-29 | 2022-06-21 | 제이에프이 스틸 가부시키가이샤 | Electric resistance welded pipe and manufacturing method thereof |
| EP4043114A4 (en) * | 2019-11-29 | 2022-08-24 | JFE Steel Corporation | Electric resistance welded steel pipe, and method for manufacturing same |
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