JP3263348B2 - Method of manufacturing non-heat treated high workability electric resistance welded steel pipe - Google Patents
Method of manufacturing non-heat treated high workability electric resistance welded steel pipeInfo
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- JP3263348B2 JP3263348B2 JP29172497A JP29172497A JP3263348B2 JP 3263348 B2 JP3263348 B2 JP 3263348B2 JP 29172497 A JP29172497 A JP 29172497A JP 29172497 A JP29172497 A JP 29172497A JP 3263348 B2 JP3263348 B2 JP 3263348B2
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- electric resistance
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、管材内面に液圧を
加えて張出し成形させる液圧成形法（ｈｙｄｒａｕｌｉ
ｃ ｆｏｒｍｉｎｇ、以下バルジ加工という）等の苛酷
な加工を受ける加工性に優れた非熱処理型電縫鋼管の製
造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic forming method (hydraulic forming method) in which a liquid pressure is applied to the inner surface of a pipe to form an overhang.
The present invention relates to a method for producing a non-heat-treated electric resistance welded steel pipe having excellent workability under severe processing such as c forming (hereinafter referred to as bulging).
【０００２】[0002]
【従来の技術】自動車業界においては、地球環境問題が
ますます注目される現在、燃料低減のための軽量化への
取り組みが最優先されるようになっている。このため、
最近では、自動車の飛躍的な軽量化を実現する方法とし
て、鋼管を素材としたバルジ加工等の苛酷な加工技術の
開発が進められている。2. Description of the Related Art In the automotive industry, as global environmental problems are increasingly attracting attention, efforts to reduce fuel weight to reduce fuel consumption have been given top priority. For this reason,
Recently, as a method of realizing a drastic weight reduction of an automobile, development of severe processing technology such as bulging using a steel pipe as a material has been advanced.
【０００３】従来の加工性に優れた鋼管の製造方法とし
ては、Ｃ：０．０１％以下、Ｓｉ：０．０５％以下、Ｍ
ｎ：０．３０ ％以下、Ｐ：０．０２５％以下、Ｓ：
０．０１５％以下、ｓｏｌ．Ａｌ：０．０８０％以下、
ＴｉまたはＮｂの１種または２種：０．００２〜０．１
０％、残部がＦｅおよび不可避的不純物からなる鋼を、
ホットストリップ仕上り温度Ａｒ3＋４０℃以上、巻取
温度５００℃以上で所定の板厚まで熱間圧延し、得られ
た熱延鋼板を冷却したのち、管状に成形して電気抵抗溶
接した鋼管を７００〜９００℃で熱処理する方法（特開
平４−３６５８１５号公報）、Ｃ：０．０１％以下、Ｓ
ｉ：０．０５％以下、Ｍｎ：０．４０ ％以下、Ｐ：
０．０２５％以下、Ｓ：０．０２５％以下、ｓｏｌ．Ａ
ｌ：０．０５０％以下、Ｂ：０．０００５〜０．００３
０ ％、残部がＦｅおよび不可避的不純物からなる鋼
を、管状体に成形し、次いで８５０〜９００℃の温度で
熱処理してなる極軟鋼管（特開昭５６−１１９７５６号
公報）等が提案されている。Conventional methods for producing a steel pipe having excellent workability include: C: 0.01% or less; Si: 0.05% or less;
n: 0.30% or less, P: 0.025% or less, S:
0.015% or less, sol. Al: 0.080% or less,
One or two of Ti or Nb: 0.002 to 0.1
0%, with the balance being Fe and unavoidable impurities,
The hot-rolled steel sheet is hot-rolled to a predetermined thickness at a hot strip finish temperature of Ar 3 + 40 ° C. or more and a winding temperature of 500 ° C. or more, and the obtained hot-rolled steel sheet is cooled. Heat treatment at -900 ° C. (JP-A-4-365815), C: 0.01% or less, S
i: 0.05% or less, Mn: 0.40% or less, P:
0.025% or less, S: 0.025% or less, sol. A
l: 0.050% or less, B: 0.0005 to 0.003
An ultra mild steel pipe (Japanese Patent Application Laid-Open No. 56-119756) or the like is proposed in which a steel containing 0% and the balance of Fe and unavoidable impurities is formed into a tubular body and then heat-treated at a temperature of 850 to 900 ° C. ing.
【０００４】[0004]
【発明が解決しようとする課題】上記特開平４−３６５
８１５号公報に開示の方法は、素材の加工性を改善する
ために添加したＴｉ、Ｎｂの焼入れ性改善効果により電
縫溶接部が硬化し、母材部と溶接部の硬度が不均一とな
るため、製管後の鋼管全体の熱処理が必須であり、熱処
理等の製造費用が増大すると共に、表面に熱処理スケー
ルが生成し、これがバルジ加工の際に金型に集積し、金
型を摩耗させる原因となる。SUMMARY OF THE INVENTION The above-mentioned Japanese Patent Laid-Open No. 4-365 is disclosed.
In the method disclosed in Japanese Patent Publication No. 815, the electric resistance welded portion is hardened by the effect of improving the hardenability of Ti and Nb added to improve the workability of the material, and the hardness of the base material portion and the welded portion becomes uneven. Therefore, heat treatment of the entire steel pipe after pipe production is indispensable, and the production cost of heat treatment and the like increases, and heat treatment scale is generated on the surface, which is accumulated in the mold during bulging and causes the mold to wear. Cause.
【０００５】特開昭５６−１１９７５６号公報に開示の
極軟鋼管は、素材の加工性を改善するために添加したＢ
の焼入れ性改善効果により電縫溶接部が硬化し、母材部
と溶接部の硬度が不均一となるため、製管後の鋼管全体
の熱処理が必須であり、熱処理等の製造費用が増大する
と共に、表面に熱処理スケールが生成し、これがバルジ
加工の際に金型に集積し、金型を摩耗させる原因とな
る。また、この極軟鋼管の用途は、水道水、ガスの配管
用鋼管であって、自動車用等の機械構造用の用途のもの
ではない。[0005] The ultra mild steel pipe disclosed in Japanese Patent Application Laid-Open No. 56-119756 is characterized in that B added in order to improve the workability of the material.
The hardening of the ERW weld is hardened by the effect of improving the hardenability of the steel, and the hardness of the base metal and the weld becomes uneven, so heat treatment of the entire steel pipe after pipe production is indispensable, and the production costs such as heat treatment increase. At the same time, a heat treatment scale is generated on the surface, which accumulates in the mold during bulging and causes the mold to wear. The extremely mild steel pipe is used for tap water and gas piping, and is not intended for use in mechanical structures such as automobiles.
【０００６】本発明の目的は、上記従来技術の欠点を解
消し、熱処理を行うことなく、製管のままで母材部と同
等の溶接部硬度が得られる非熱処理型高加工性電縫鋼管
の製造方法を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a non-heat-treated, high-workability, electric-resistance-welded steel pipe capable of obtaining a weld hardness equivalent to that of a base material without heat treatment. It is to provide a manufacturing method of.
【０００７】[0007]
【課題を解決するための手段】本発明の請求項１の非熱
処理型高加工性電縫鋼管の製造方法は、Ｃ：０．０７％
以下、Ｓｉ：０．５％以下、Ｍｎ：０．５％以下、Ｐ：
０．０３％以下、Ｓ：０．０２％以下、Ｂ：０．０００
５〜０．００４０％を含有し、残部がＦｅおよび不可避
的不純物からなる鋼スラブを、１１００〜１２８０℃の
温度範囲に加熱したのち、仕上温度Ａｒ3変態点以上、
巻取温度５８０℃以上で熱間圧延し、得られた熱延コイ
ルを素材として使用し、成形ロール群により円筒状に連
続成形したオープンパイプの両エッジ部２〜４ｍｍ幅を
７００〜１０００℃に予熱したのち、本加熱して電縫溶
接し、溶接部を放冷することにより冷却速度を低下させ
て溶接部でのマルテンサイトやベイナイトの生成を抑制
し、電縫溶接のままで母材部と同等の溶接部硬度とす
る。According to a first aspect of the present invention, there is provided a method for producing a non-heat-treated high-workability ERW steel pipe, comprising: C: 0.07%
Hereinafter, Si: 0.5% or less, Mn: 0.5% or less, P:
0.03% or less, S: 0.02% or less, B: 0.000
After heating a steel slab containing 5 to 0.0040%, the balance being Fe and unavoidable impurities, to a temperature range of 1100 to 1280 ° C, the finishing temperature Ar 3 transformation point or higher,
Hot rolling at a winding temperature of 580 ° C or higher, and using the obtained hot-rolled coil as a raw material, the width of both edges of the open pipe continuously formed into a cylindrical shape by a group of forming rolls is increased to 700 to 1000 ° C. After preheating, main heating and ERW welding are performed, and the cooling rate is reduced by allowing the weld to cool.
Of martensite and bainite in welds by welding
The same weld hardness as that of the base metal
You .
【０００８】このように、上記化学成分の鋼スラブを、
１１００〜１２８０℃の温度範囲に加熱したのち、仕上
温度Ａｒ3変態点以上、巻取温度５８０℃以上で熱間圧
延し、得られた熱延コイルを素材として使用し、成形ロ
ール群により円筒状に連続成形したオープンパイプの両
エッジ部２〜４ｍｍ幅を７００〜１０００℃に予熱した
のち、本加熱して電縫溶接し、溶接部を放冷することに
より冷却速度を低下させて溶接部でのマルテンサイトや
ベイナイトの生成を抑制し、電縫溶接のままで母材部と
同等の溶接部硬度とすることによって、電縫溶接のまま
で母材部とほぼ同等の溶接部硬度を得ることができ、製
管後の熱処理を不要とすることができる。Thus, the steel slab having the above chemical composition is
After heating to a temperature range of from 1,100 to 1,280 ° C., finishing temperature Ar 3 transformation point or more, then hot rolled at the coiling temperature 580 ° C. or higher, using the hot rolled coil obtained as a material, a cylindrical shape by molding rolls especially the After preheating both edges 2~4mm width of the open pipe to 700 to 1000 ° C. continuous molding, and electric resistance welding by the heat, allowed to cool weld
By lowering the cooling rate further,
Suppresses the formation of bainite.
By setting the same weld hardness, it is possible to obtain a weld hardness almost equal to that of the base material portion in the electric resistance welding as it is, and it becomes unnecessary to perform a heat treatment after pipe making.
【０００９】[0009]
【発明の実施の形態】本発明の請求項１の非熱処理型高
加工性電縫鋼管の製造方法においては、熱延コイルを素
材として使用し、オープンパイプの両エッジ部２〜４ｍ
ｍ幅を７００〜 １０００℃に予熱したのち、本加熱し
て電縫溶接し、電縫溶接部を放冷することにより冷却速
度を低下させて溶接部でのマルテンサイトやベイナイト
の生成を抑制し、電縫溶接のままで母材部と同等の溶接
部硬度とするので、予備加熱により溶接部の熱量が多く
なって、冷却速度を低下させることとなり、溶接部にマ
ルテンサイト、ベイナイトの焼入れ組織の生成が阻止さ
れ、電縫溶接のままで母材部とほぼ同等の溶接部硬度を
得ることができ、製管後の熱処理を不要とできる。この
ため、熱処理コストを削減できると共に、バルジ加工時
における金型に悪影響を及ぼすスケール問題もなく、良
好な加工が可能となる。DETAILED DESCRIPTION OF THE INVENTION In the method for producing a non-heat-treated high-workability ERW steel pipe according to the first aspect of the present invention, a hot-rolled coil is used as a material, and both edges of an open pipe are 2 to 4 m.
After preheating the m width 700 to 1000 ° C., and electric resistance welding by the heating, cooling speed by cooling the electric resistance welding portion
Martensite and bainite in welds with reduced degrees
Generation is suppressed, and welding equivalent to that of the base metal is performed with ERW welding
Since the parts hardness, an increasing number of heat of the weld by preheating, will be to reduce the cooling rate, the martensite, the generation of bainite hardened structure is prevented in the welded portion, the base material remains electric resistance welding It is possible to obtain a weld hardness almost equal to that of the welded portion, and it becomes unnecessary to perform a heat treatment after pipe production. For this reason, the heat treatment cost can be reduced, and good processing can be performed without a scale problem that adversely affects the mold during bulging.
【００１０】本発明において鋼スラブの化学成分を限定
したのは、下記の理由による。Ｃは、鋼の機械的強度を
上昇させ、加工性を低下させるため、極力低い方が好ま
しく、０．０７％を超えると強度が上昇して加工性が低
下するため、０．０７％以下とした。In the present invention, the chemical components of the steel slab are limited for the following reasons. C is preferably as low as possible in order to increase the mechanical strength of the steel and reduce the workability, and if C exceeds 0.07%, the strength increases and the workability decreases, so C is set to 0.07% or less. did.
【００１１】Ｓｉは、鋼中の脱酸元素として有効な元素
であるが、０．５％を超えると部品となった時点での溶
接性を損なうため、０．５％以下とした。[0011] Si is an effective element as a deoxidizing element in steel, but if it exceeds 0.5%, the weldability at the time of forming a part is impaired.
【００１２】Ｍｎは、鋼の靭性を確保するために必要不
可欠な元素であるが、０．５％を超えると強度が上昇し
て加工性が低下するため、０．５％以下とした。Mn is an indispensable element for ensuring the toughness of the steel, but if it exceeds 0.5%, the strength increases and the workability decreases, so Mn is set to 0.5% or less.
【００１３】Ｐは、０．０３％を超えると粒界に析出
し、加工性を損なうため、０．０３％以下とした。If P exceeds 0.03%, it precipitates at the grain boundary and impairs the workability. Therefore, the content of P is set to 0.03% or less.
【００１４】Ｓは、０．０２％を超えるとＭｎと結合し
てＭｎＳとして介在物となり、加工性を損なうため、
０．０２％以下とした。If S exceeds 0.02%, S combines with Mn to form inclusions as MnS, impairing workability.
0.02% or less.
【００１５】Ｂは、一般に鋼のＡｒ3変態点を低下さ
せ、熱間圧延後の粒成長を助長し、結果として素材コイ
ルを軟化させて加工性を向上させる元素であるが、０．
０００５％以下ではその効果が得られず、また、０．０
４０％を超えると粒界に析出し、粒界強度を低下させ、
かえって加工性を損なうため、０．０００５〜０．０４
０％とした。B is an element that generally lowers the Ar 3 transformation point of steel, promotes grain growth after hot rolling, and consequently softens the material coil to improve workability.
Below 0005%, the effect cannot be obtained.
If it exceeds 40%, it precipitates at the grain boundaries, lowering the grain boundary strength,
On the contrary, 0.0005 to 0.04 to impair workability
0%.
【００１６】本発明において鋼スラブの加熱温度、熱延
条件、冷間圧延条件、オープンパイプの両エッジ部の加
熱条件を限定したのは、下記の理由による。In the present invention, the heating temperature of the steel slab, the hot rolling condition, the cold rolling condition, and the heating condition of both edges of the open pipe are limited for the following reasons.
【００１７】鋼スラブの加熱温度は、１１００℃未満で
は圧延温度として低すぎるため、熱間圧延における仕上
温度をＡｒ3変態点以上に維持することができなくなる
と共に、低温度で仕上圧延することとなり、圧延設備の
負荷の増大を招き、また、１２８０℃を超えると肌荒
れ、スケール押込み等スラブ表面性状が低下するため、
１１００〜 １２８０℃とした。If the heating temperature of the steel slab is less than 1100 ° C., the rolling temperature is too low, so that the finishing temperature in hot rolling cannot be maintained at the Ar 3 transformation point or higher, and the finishing rolling is performed at a low temperature. , Causes an increase in the load on the rolling equipment, and, when the temperature exceeds 1280 ° C., the surface of the slab such as roughened surface and indentation of the scale is reduced.
1100-1280 degreeC.
【００１８】熱間圧延における仕上温度は、Ａｒ3変態
点以上であれば鋼帯の結晶粒の成長により十分な加工性
を確保できるが、Ａｒ3変態点からの粒成長を確保して
さらに加工性を好転させるためには極力高い温度で仕上
げるのが好ましい。[0018] Temperature finish in hot rolling, can ensure a sufficient workability the grain growth of the steel strip if Ar 3 transformation point or higher, further processed to ensure grain growth from Ar 3 transformation point In order to improve the properties, it is preferable to finish at as high a temperature as possible.
【００１９】熱間圧延における巻取温度は、５８０℃未
満ではセルフテンパー効果による加工性の向上が望めな
いので、５８０℃以上とした。If the winding temperature in the hot rolling is lower than 580 ° C., the workability cannot be improved by the self-tempering effect.
【００２０】オープンパイプの両エッジ部の加熱につい
て、一般に、周波数 ｆ を小さくしていくと、エッジ
部での電流浸透深さδ（δ＝５．０３√（ρ／ｆ・μ）
ｃｍ、μ ： 比透磁率、ρ ： 固有抵抗μΩ−ｃ
ｍ、ｆ ： 周波数Ｈｚ）が大きくなり、加熱幅が広く
なり、溶接部冷却特性が改善される傾向にある。したが
って、本発明において成形ロール群で円筒状に連続成形
したオープンパイプの両エッジ部の予熱幅は、図１に示
すとおり、予熱幅Ｗが２ｍｍ〜４ｍｍとなるよう、高周
波予熱装置の周波数 ｆ を適正に選択すればよい。な
お、予熱幅Ｗが２ｍｍ未満では、入熱が不十分で、熱量
そのものが少ないため急激に温度が低下することとなっ
て、溶接部の急冷が改善されず、また、４ｍｍを超える
と、予熱効果が変わらず、入熱量が多すぎて電力が無駄
となるため、２ｍｍ〜４ｍｍとした。As for the heating of both edges of the open pipe, generally, as the frequency f is reduced, the current penetration depth δ at the edges (δ = 5.03√ (ρ / f · μ)
cm, μ: relative magnetic permeability, ρ: specific resistance μΩ-c
m, f: frequency Hz), the heating width is widened, and the cooling characteristics of the welded portion tend to be improved. Therefore, the preheating width of both edges of the open pipe continuously formed into a cylindrical shape by the forming roll group in the present invention is set to a frequency f of the high-frequency preheating device so that the preheating width W is 2 mm to 4 mm as shown in FIG. What is necessary is just to select appropriately. If the preheating width W is less than 2 mm, the heat input is insufficient, and the amount of heat itself is small, so that the temperature drops rapidly, and the quenching of the weld is not improved. Since the effect does not change and the amount of heat input is too large and power is wasted, the thickness is set to 2 mm to 4 mm.
【００２１】本発明において成形ロール群で円筒状に連
続成形したオープンパイプの両エッジ部の予熱温度は、
７００℃未満では熱量そのものが少ないため、急激に温
度が低下することとなって、電縫溶接部の急冷を防ぐ熱
量として予熱不十分で、また、１０００℃を超えると電
縫溶接時に溶け落ちが生じたり、メタルフロー形成が悪
く溶鋼排出が不十分で溶接品質が悪化するため、７００
℃〜１０００℃とした。In the present invention, the preheating temperature of both edges of the open pipe continuously formed into a cylindrical shape by the forming roll group is as follows:
If the temperature is less than 700 ° C, the amount of heat itself is small, so that the temperature rapidly drops, and the preheating is insufficient as the amount of heat to prevent the quenching of the electric resistance welded portion. Or the metal flow formation is poor and the molten steel discharge is inadequate and the welding quality deteriorates.
C. to 1000.degree.
【００２２】本発明における溶接時の本加熱は、通常の
電縫溶接時の加熱温度である１２００〜 １４００℃で
ある。１２００℃未満では接合面温度が低く溶接が不完
全でコールドウェルドなどが生じ易く、また、１４００
℃を超えると接合面圧力低下のため、溶け落ちなどが生
じるほか、ペネトレータが発生したり、スパッタの増加
やビードが大型化して作業性の低下を招くこととなる。The main heating during welding in the present invention is 1200 to 1400 ° C., which is the heating temperature during normal electric resistance welding. If the temperature is lower than 1200 ° C., the joining surface temperature is low and welding is incomplete, so that cold welding or the like is likely to occur.
If the temperature exceeds ℃, the pressure at the bonding surface decreases, so that burn-through occurs, penetrators are generated, spatter increases, and beads are increased in size, resulting in a decrease in workability.
【００２３】本発明において電縫溶接後に溶接部を放冷
することにより冷却速度を低下させて溶接部でのマルテ
ンサイトやベイナイトの生成を抑制し、電縫溶接のまま
で母材部と同等の溶接部硬度としたのは、電縫溶接後の
急冷により溶接部にマルテンサイト、ベイナイトの焼入
れ組織が生成するのを阻止し、電縫溶接のままで母材部
と同等の溶接部硬度とするためである。In the present invention, the weld is allowed to cool after ERW welding
To reduce the cooling rate,
Suppresses the formation of incites and bainite, and remains ERW
The reason for setting the weld hardness to the same as that of the base metal part is that quenching after ERW prevents the formation of martensite and bainite quenched structure in the weld, and
This is because the hardness of the welded portion is equivalent to that of.
【００２４】本発明においては、電縫溶接前にオープン
パイプの両エッジ部２〜４ｍｍ幅を７００℃〜１０００
℃に予熱するので、電縫溶接時の入熱量を成分や管の肉
厚によって制御できるため、過剰な電力消費を避けるこ
とができる。In the present invention, before the electric resistance welding, the width of both edges of the open pipe at 2 mm to 4 mm is adjusted to 700 ° C. to 1000 mm.
Since the temperature is preheated to ° C., the amount of heat input during the electric resistance welding can be controlled by the components and the wall thickness of the pipe, so that excessive power consumption can be avoided.
【００２５】[0025]
【実施例】表１に示す鋼種Ａ〜Ｅの化学組成の鋼を溶製
したのち、表２に示す熱延条件等で製造した板厚２．０
０ｍｍ〜３．００ｍｍのコイルを素材として使用し、成
形ロールにより円筒状に連続成形したオープンパイプの
両エッジ部を、表３に示す予熱条件で予熱した場合と、
予熱しない場合のそれぞれについて、２８０ＫＨｚの高
周波電流を用いて電縫溶接し、外径３８．１ｍｍ〜７
０．０ｍｍ、肉厚２．００ｍｍ〜３．００ｍｍの電縫鋼
管を製造した。得られた各電縫鋼管から試験片を採取
し、ＪＩＳ Ｚ２２４１に規定の金属材料引張試験方法
に準じて引張強さ、全伸びを測定すると共に、ＪＩＳ
Ｚ２２４４に規定のビッカース硬さ試験方法に準じて試
験荷重４９．０３Ｎにおけるビッカース硬さを測定し
た。その結果を表４に示す。EXAMPLE Steels having the chemical compositions of steel types A to E shown in Table 1 were smelted and then produced under hot rolling conditions and the like shown in Table 2 to a thickness of 2.0.
Using a coil of 0 mm to 3.00 mm as a raw material, both edges of an open pipe continuously formed into a cylindrical shape by a forming roll are preheated under preheating conditions shown in Table 3,
For each case without preheating, electric resistance welding was performed using a high-frequency current of 280 KHz, and the outer diameter was 38.1 mm to 7 mm.
An electric resistance welded steel pipe having a thickness of 0.0 mm and a thickness of 2.00 mm to 3.00 mm was manufactured. A test piece was collected from each of the obtained electric resistance welded steel pipes, and the tensile strength and the total elongation were measured according to the metal material tensile test method specified in JIS Z2241.
Vickers hardness at a test load of 49.03 N was measured according to the Vickers hardness test method specified in Z2244. Table 4 shows the results.
【００２６】[0026]
【表１】 [Table 1]
【００２７】[0027]
【表２】 [Table 2]
【００２８】[0028]
【表３】 [Table 3]
【００２９】[0029]
【表４】 [Table 4]
【００３０】表１〜表４に示すとおり、Ｂを含有しない
鋼種Ｄを用いた比較例の試験Ｎｏ．４の鋼管は、同程度
の成分系の鋼種Ｂを用いた実施例の試験Ｎｏ．２の鋼管
に比較し、引張強さが５０Ｎ／ｍｍ2上昇し、伸びが下
がり、母材硬度も上昇しており、加工性が劣っている。
また、鋼種Ｅを用いた巻取温度が本発明の範囲外の比較
例の試験Ｎｏ．５の鋼管は、セルフテンパー効果が得ら
れず、同程度の成分系の鋼種Ｂを用いた実施例の試験Ｎ
ｏ．２の鋼管に比較し、引張強さが６０Ｎ／ｍｍ2上昇
し、加工性が劣っている。さらに、鋼種Ａを用いた予熱
条件が本発明の範囲外の比較例の試験Ｎｏ．６の鋼管
は、溶接部硬度と母材部硬度の差がビッカース硬さで５
４と大きくなっている。さらにまた、鋼種Ｃを用いたオ
ープンパイプ両エッジ部の予熱をしなかった比較例の試
験Ｎｏ．７の鋼管は、溶接部硬度と母材部硬度の差がビ
ッカース硬さで５７と大きくなっている。これに対し、
鋼種Ａ〜Ｃを用いた実施例の試験Ｎｏ．１〜３の鋼管
は、製管のままで、溶接部硬度と母材部硬度の差がビッ
カース硬さで０〜５とほぼ同じ硬度を示しており、加工
性に優れた電縫鋼管を得ることができた。As shown in Tables 1 to 4, Test No. 1 of Comparative Example using steel type D containing no B was used . 4 of the steel pipe is tested embodiment using the steel type B a comparable component No. As compared with the steel pipe No. 2 , the tensile strength increased by 50 N / mm 2 , the elongation decreased, the base metal hardness also increased, and the workability was poor.
In addition, in Test No. of the comparative example in which the winding temperature using steel type E was out of the range of the present invention . The steel pipe No. 5 did not exhibit the self-tempering effect, and the test N of the example using the steel type B of the same component system
o. As compared with the steel pipe No. 2 , the tensile strength increased by 60 N / mm 2 and the workability was inferior. Furthermore, the test No. of the comparative example in which the preheating condition using steel type A is out of the range of the present invention . In the steel pipe of No. 6 , the difference between the hardness of the welded part and the hardness of the base metal part is 5 in Vickers hardness.
It is as large as four. Furthermore, the test No. of the comparative example which did not preheat both edges of the open pipe using steel type C. In the steel pipe No. 7 , the difference between the weld hardness and the base metal hardness is as large as 57 in Vickers hardness. In contrast,
Test No. of the example using steel types A to C. As for the steel pipes 1 to 3 , the difference between the welded part hardness and the base metal part hardness is almost the same as the Vickers hardness of 0 to 5 as it is in the form of a pipe, and an ERW steel pipe excellent in workability is obtained. I was able to.
【００３１】[0031]
【発明の効果】本発明の請求項１の非熱処理型高加工性
電縫鋼管の製造方法においては、電縫溶接のままで母材
部とほぼ同等な溶接部硬度を得ることができ、製管後の
熱処理を不要とできるので、熱処理コストを削減できる
と共に、バルジ加工時における金型に悪影響を及ぼすス
ケール問題もなく、良好な加工が可能となる。According to the method for producing a non-heat-treated high-workability ERW steel pipe according to the first aspect of the present invention, it is possible to obtain almost the same weld hardness as that of the base material while maintaining ERW. Since the heat treatment after the pipe is not required, the heat treatment cost can be reduced, and good processing can be performed without a scale problem that adversely affects a mold at the time of bulging.
【図１】コイル両エッジ部の加熱幅の説明図である。FIG. 1 is an explanatory diagram of a heating width of both edge portions of a coil.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平２−299783（ＪＰ，Ａ) 特開 昭58−161722（ＪＰ，Ａ) 特開 平８−193244（ＪＰ，Ａ) 特開 平８−319538（ＪＰ，Ａ) 特開 平８−246095（ＪＰ，Ａ) 特開 平９−143612（ＪＰ，Ａ) 特開 平５−212439（ＪＰ，Ａ) 特開 平４−263019（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B21C 37/08 C21D 8/02 C21D 8/10 C22C 38/00 301 C22C 38/04 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-299783 (JP, A) JP-A-58-161722 (JP, A) JP-A-8-193244 (JP, A) JP-A-8-193244 319538 (JP, A) JP-A-8-246095 (JP, A) JP-A-9-143612 (JP, A) JP-A-5-212439 (JP, A) JP-A-4-263019 (JP, A) (58) Field surveyed (Int. Cl. 7 , DB name) B21C 37/08 C21D 8/02 C21D 8/10 C22C 38/00 301 C22C 38/04
Claims (1)
下、Ｍｎ：０．５％以下、Ｐ：０．０３％以下、Ｓ：
０．０２％以下、Ｂ：０．０００５〜０．００４０％を
含有し、残部がＦｅおよび不可避的不純物からなる鋼ス
ラブを、１１００〜１２８０℃の温度範囲に加熱したの
ち、仕上温度Ａｒ3変態点以上、巻取温度５８０℃以上
で熱間圧延し、得られた熱延コイルを素材として使用
し、成形ロール群により円筒状に連続成形したオープン
パイプの両エッジ部２〜４ｍｍ幅を７００〜１０００℃
に予熱したのち、本加熱して電縫溶接し、溶接部を放冷
することにより冷却速度を低下させて溶接部でのマルテ
ンサイトやベイナイトの生成を抑制し、電縫溶接のまま
で母材部と同等の溶接部硬度とすることを特徴とする非
熱処理型高加工性電縫鋼管の製造方法。1. C: 0.07% or less, Si: 0.5% or less, Mn: 0.5% or less, P: 0.03% or less, S:
After heating a steel slab containing 0.02% or less and B: 0.0005 to 0.0040%, the balance being Fe and unavoidable impurities, to a temperature range of 1100 to 1280 ° C, a finishing temperature of Ar 3 transformation Hot rolled at a winding temperature of 580 ° C. or higher, and using the obtained hot-rolled coil as a raw material, the both ends of an open pipe continuously formed into a cylindrical shape by a group of forming rolls and a width of 2 to 4 mm are 700 to 700 mm. 1000 ° C
After the main heating, the main heating is performed, the electric resistance welding is performed, and the cooling rate is reduced by allowing the welded part to cool.
Suppresses the formation of incites and bainite, and remains ERW
A method for producing a non-heat-treated high-workability ERW steel pipe, wherein the welded part hardness is equal to that of the base material part .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29172497A JP3263348B2 (en) | 1997-10-07 | 1997-10-07 | Method of manufacturing non-heat treated high workability electric resistance welded steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29172497A JP3263348B2 (en) | 1997-10-07 | 1997-10-07 | Method of manufacturing non-heat treated high workability electric resistance welded steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11114624A JPH11114624A (en) | 1999-04-27 |
| JP3263348B2 true JP3263348B2 (en) | 2002-03-04 |
Family
ID=17772581
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29172497A Expired - Fee Related JP3263348B2 (en) | 1997-10-07 | 1997-10-07 | Method of manufacturing non-heat treated high workability electric resistance welded steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3263348B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6518533B1 (en) * | 2001-11-01 | 2003-02-11 | Ltv Steel Company, Inc. | High strength steel tubing |
| CN104911325A (en) * | 2008-07-11 | 2015-09-16 | Skf公司 | A method for manufacturing a steel component, a weld seam, a welded steel component, and a bearing component |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58161722A (en) * | 1982-03-20 | 1983-09-26 | Nippon Steel Corp | Production of hot rolled steel plate of blank material for electric resistance welded pipe having excellent bending workability of pipe |
| JPH02299783A (en) * | 1989-05-11 | 1990-12-12 | Sumitomo Metal Ind Ltd | Manufacture of resistance welded tube |
| JPH04263019A (en) * | 1990-12-29 | 1992-09-18 | Nkk Corp | High strength resistance welded tube for vehicle door impact bar reduced in bending |
| JP2613155B2 (en) * | 1991-09-07 | 1997-05-21 | 新日本製鐵株式会社 | ERW oil well pipe excellent in crushing characteristics and method of manufacturing the same |
| JP3916172B2 (en) * | 1995-01-18 | 2007-05-16 | 新日本製鐵株式会社 | Soft hot rolled steel sheet excellent in ductility and method for producing the same |
| JPH08246095A (en) * | 1995-03-07 | 1996-09-24 | Nkk Corp | Low yield ratio and high toughness steel for square steel pipe and its production |
| JP3390596B2 (en) * | 1995-03-23 | 2003-03-24 | 川崎製鉄株式会社 | Low yield ratio high strength hot rolled steel sheet excellent in toughness and method for producing the same |
| JPH09143612A (en) * | 1995-11-21 | 1997-06-03 | Kobe Steel Ltd | High strength hot rolled steel plate member low in yield ratio |
-
1997
- 1997-10-07 JP JP29172497A patent/JP3263348B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11114624A (en) | 1999-04-27 |
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