JP2000119750A - Production of high strength steel tube for hollow stabilizer excellent in fatigue durability - Google Patents
Production of high strength steel tube for hollow stabilizer excellent in fatigue durabilityInfo
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- JP2000119750A JP2000119750A JP10296606A JP29660698A JP2000119750A JP 2000119750 A JP2000119750 A JP 2000119750A JP 10296606 A JP10296606 A JP 10296606A JP 29660698 A JP29660698 A JP 29660698A JP 2000119750 A JP2000119750 A JP 2000119750A
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- transformation point
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車の走行安定性を
保持する中空スタビライザに使用される高強度電縫鋼管
の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high-strength electric resistance welded steel pipe used for a hollow stabilizer for maintaining the running stability of an automobile.
【０００２】[0002]
【従来の技術】自動車の燃費向上に関する改善は急速に
進められており、その対策の一つとして軽量化が種々検
討されている。たとえば、コーナリング時に車体のロー
リングを緩和し、高速走行時に車体の安定性を保持する
スタビライザとして、ＳＵＰ６，Ｓ４５Ｃ等の棒鋼をス
タビライザ形状に加工した後、焼入れ・焼戻し処理した
中実スタビライザに替えて、Ｓ２０Ｃ等の継目無し鋼
管，電縫鋼管等に焼入れ・焼戻し処理を施した軽量な中
空スタビライザが一部で使用されている。最近では、更
にコスト低減及び軽量化を図るため、熱延材を用い、焼
入れ・焼戻し処理を省略したアズロール型中空スタビラ
イザが検討されるようになってきた。アズロール型中空
スタビライザの製造法としても、調質熱処理を前提にし
た従来の中空スタビライザのように比較的強度の低い鋼
管を用いて複雑な曲げ加工を施す方法に替え、高強度鋼
管を用いて比較的単純な形状に成形加工し、他の部品を
アーク溶接等で接合する方法も採用され始めている。そ
のため、中空スタビライザとして使用される電縫鋼管に
は、電縫溶接部だけでなく、アーク溶接等による他部品
との接合部における熱影響部についても硬化又は軟化が
生じ難く、疲労耐久性に優れていることが要求される。2. Description of the Related Art Improvements in improving the fuel efficiency of automobiles are being rapidly promoted, and various measures are being taken to reduce the weight as one of the measures. For example, as a stabilizer that eases rolling of the vehicle body during cornering and maintains the stability of the vehicle body during high-speed running, bar steel such as SUP6 and S45C is processed into a stabilizer shape, and then replaced with a solid stabilizer that is quenched and tempered. A lightweight hollow stabilizer obtained by quenching and tempering a seamless steel pipe such as S20C, an electric resistance welded steel pipe, or the like is used. Recently, in order to further reduce costs and reduce weight, an as-roll type hollow stabilizer using a hot-rolled material and omitting quenching and tempering treatments has been studied. The manufacturing method of the as-roll type hollow stabilizer is also compared with the method using a high-strength steel pipe, replacing the method of performing a complicated bending process with a relatively low-strength steel pipe like the conventional hollow stabilizer that presupposes heat treatment. It has also begun to adopt a method of forming a simple shape and joining other parts by arc welding or the like. Therefore, in the ERW steel pipe used as the hollow stabilizer, hardening or softening hardly occurs not only in the ERW weld but also in the heat-affected zone at the joint with other parts by arc welding etc., and it has excellent fatigue durability. Is required.
【０００３】[0003]
【発明が解決しようとする課題】アズロール型中空スタ
ビライザ用の電縫鋼管としてこれまで種々の提案がされ
ているが、電縫溶接部に加え他部品との接合部における
熱影響部についても十分な特性を備えた電縫鋼管が得ら
れていないことが現状である。たとえば、Ｃ含有量を
０．０８〜０．２３重量％とし、Ｍｎ，Ｓｉ，Ｎｂ等を
特定量以下に規制し、Ｃｒ，Ｍｏの１種又は２種を特定
量以下で添加した鋼を熱間圧延した後、電縫溶接し、造
管のままで、或いは歪取り焼鈍して引張強さ６０〜１０
０ｋｇｆ／ｍｍ2 の鋼管が得られることが特開平２−１
９７５２５号公報で紹介されている。また、特開平６−
１００４６号公報では、溶接時の熱影響部が軟化し難い
成分設計を採用し、疲労強度が改善された引張強さ１０
０〜１３０ｋｇｆ／ｍｍ2 の鋼管を得ている。しかし、
何れも中炭素鋼にＣｒ：０．３〜１．０重量％又はＭ
ｏ：０．３〜１．０重量％を添加した鋼材であり、コス
ト高になると共に、溶接熱影響部にベイナイト，マルテ
ンサイト等の低温変態相が生じ易い。そのため、高強度
鋼管と他部品とを溶接した場合に溶接接合部の熱影響部
に生じ易い硬化又は軟化によって、疲労特性がばらつき
やすい電縫鋼管である。Various ERW steel pipes for an as-roll type hollow stabilizer have been proposed so far. However, in addition to ERW welds, sufficient heat-affected zones at joints with other parts are not sufficient. At present, an electric resistance welded steel pipe having characteristics has not been obtained. For example, C content is set to 0.08 to 0.23% by weight, Mn, Si, Nb and the like are regulated to a specific amount or less, and steel to which one or two types of Cr and Mo are added in a specific amount or less is heated. After rolling during rolling, ERW welding, as-tube-formed or strain-relieving annealing is applied to tensile strength of 60 to 10
It has been found that a steel pipe of 0 kgf / mm 2 can be obtained.
No. 97525. In addition, Japanese Unexamined Patent Publication No.
Japanese Patent Application Publication No. 10046 discloses a component design in which the heat-affected zone during welding is hardly softened, and has a tensile strength of 10 with improved fatigue strength.
A steel pipe of 0 to 130 kgf / mm 2 is obtained. But,
In any case, Cr: 0.3 to 1.0% by weight or M in medium carbon steel
o: A steel material containing 0.3 to 1.0% by weight, which increases the cost and easily causes a low-temperature transformation phase such as bainite and martensite in the heat affected zone. Therefore, when the high-strength steel pipe is welded to another component, the electric resistance welded steel pipe has a fatigue characteristic that tends to vary due to hardening or softening that easily occurs in the heat-affected zone of the welded joint.
【０００４】[0004]
【課題を解決するための手段】本発明は、このような問
題を解消すべく案出されたものであり、微細フェライト
と微細パーライトの混合組織にＴｉ，Ｎｂを含む析出物
が微細に分散した金属組織とすることにより、他部品と
溶接した場合に溶接接合部の熱影響部に硬化や軟化が生
じ難く、６９０〜１１００Ｎ／ｍｍ2 の引張強さを示す
電縫鋼管を低コストで製造することを目的とする。SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and a precipitate containing Ti and Nb is finely dispersed in a mixed structure of fine ferrite and fine pearlite. By using a metal structure, hardening or softening hardly occurs in the heat-affected zone of the welded joint when welding with other parts, and an electric resistance welded steel pipe showing a tensile strength of 690 to 1100 N / mm 2 is manufactured at low cost. The purpose is to:
【０００５】本発明の製造方法は、その目的を達成する
ため、Ｃ：０．０３〜０．１０重量％，Ｓｉ：０．２０
〜１．０重量％，Ｍｎ：１．０〜２．５重量％，Ｐ：
０．０３重量％以下，Ｓ：０．００５重量％以下，（Ｎ
＋Ｏ）：１５０ｐｐｍ以下，Ｔｉ：０．０２〜０．２０
重量％，Ｎｂ：０．０２〜０．１０重量％，トータルＡ
ｌ：０．０１〜０．１重量％，残部が実質的にＦｅの組
成をもつスラブを１１５０〜１３００℃に加熱した後、
仕上げ圧延でのトータル圧延率：９０％以上，仕上げ温
度：Ａr3変態点〜Ａr3変態点＋１００℃で熱間圧延し、
冷却速度１０〜５０℃／秒で冷却し、巻取り温度４５０
〜５５０℃で巻き取って熱延コイルとし、該熱延コイル
を酸洗後に電縫鋼管とする際、電縫溶接部の冷却後に連
続して高周波加熱により電縫溶接部をＡc1変態点〜Ａc1
変態点−７０℃の温度域で焼き戻すことを特徴とする。[0005] The production method of the present invention, in order to achieve the object, C: 0.03 to 0.10 wt%, Si: 0.20%.
To 1.0% by weight, Mn: 1.0 to 2.5% by weight, P:
0.03% by weight or less, S: 0.005% by weight or less, (N
+ O): 150 ppm or less, Ti: 0.02 to 0.20
Wt%, Nb: 0.02 to 0.10 wt%, total A
l: After heating a slab having a composition of 0.01 to 0.1% by weight, with the balance being substantially Fe, to 1150 to 1300 ° C,
Total rolling reduction at the finish rolling: 90%, finishing temperature: hot rolling at A r3 transformation point to A r3 transformation point + 100 ° C.,
Cool at a cooling rate of 10 to 50 ° C./sec.
When the hot-rolled coil is taken up at 550 ° C. to form a hot-rolled coil, and the hot-rolled coil is made into an ERW steel pipe after being pickled, the ERW weld is continuously cooled by cooling the ERW weld to the A c1 transformation point by high frequency heating. A c1
It is characterized by tempering in a temperature range of a transformation point of -70 ° C.
【０００６】使用する鋼材は、更にＢ：０．００５０重
量％以下，Ｃｒ：０．３重量％以下，Ｃａ：０．００５
０重量％以下の１種又は２種以上を含むことができる。
熱間圧延時に、９００〜１１００℃の温度域でデスケー
ラ吐出圧力２００ｋｇｆ／ｃｍ2 以上のデスケールを少
なくとも１パス以上実施すると、疲労破壊の起点となる
欠陥部のない良好な表面をもつ熱延鋼帯が得られる。電
縫鋼管は、疲労耐久性及び軽量化を両立させる上で、肉
厚をＴ，外径をＤとして０．０７〜０．１５の肉厚外径
比Ｔ／Ｄをもつことが好ましい。[0006] The steel materials used are B: 0.0050% by weight or less, Cr: 0.3% by weight or less, and Ca: 0.005% by weight.
One or more of 0% by weight or less can be contained.
A hot-rolled steel strip having a good surface without a defect portion which becomes a starting point of fatigue fracture when at least one pass of descaling with a descaler discharge pressure of 200 kgf / cm 2 or more is performed in a temperature range of 900 to 1100 ° C. during hot rolling. Is obtained. The electric resistance welded steel pipe preferably has a wall thickness ratio T / D of 0.07 to 0.15, where T is the wall thickness and D is the outer diameter, for achieving both fatigue durability and weight reduction.
【０００７】[0007]
【作用】本発明者等は、中空スタビライザの要求特性を
満足させるため、電縫鋼管の機械的性質に及ぼす成分条
件，製造条件等を調査検討した。その結果、強度確保に
有効であるＣ量を可能な限り低く抑えて溶接部の延性を
確保し、Ｔｉ，Ｎｂの炭窒化物生成及び細粒化効果を活
用して溶接熱影響部の軟化及び硬化を抑制することが有
効であることを見出した。また、強度を向上させ、電縫
溶接部やアーク溶接部の硬度差を小さくする上では微細
なフェライト＋パーライト組織が効果的であることを解
明し、このような組織を得るための成分条件及び製造条
件を適正化した。In order to satisfy the required characteristics of the hollow stabilizer, the present inventors have investigated and studied the component conditions, the manufacturing conditions, and the like that affect the mechanical properties of the ERW steel pipe. As a result, the C content effective for ensuring the strength is kept as low as possible to secure the ductility of the welded portion, and the softening of the weld heat affected zone and the effect of the carbonitride generation and grain refinement of Ti and Nb are utilized. It has been found that suppressing curing is effective. In addition, it was clarified that a fine ferrite + pearlite structure was effective in improving the strength and reducing the hardness difference between the electric resistance welded portion and the arc welded portion. Manufacturing conditions have been optimized.
【０００８】以下、本発明で使用する鋼材の合金成分，
含有量，製造条件等を説明する。Ｃ：０．０３〜０．１０重量％ 強度を確保する上で重要な合金成分である。Ｃ含有量が
少ないほど溶接部の延性が良くなるものの、鋼管の強度
が低下することから、本発明ではＣ含有量の下限を０．
０３重量％に設定した。しかし、０．１０重量％を超え
る多量のＣが含まれると、ベイナイト又はマルテンサイ
ト組織となり、加工性及び疲労耐久性が劣化する傾向が
みられる。また、溶接熱影響部が軟化しやすくなる。Ｓｉ：０．２０〜１．０重量％ 固溶強化型の合金成分であり、本発明のようにＣ含有量
を下げた鋼種にあっては、強度確保のために少なくとも
０．２０重量％以上が必要である。しかし、１．０重量
％を超える多量のＳｉが含まれると、スラブ加熱時にフ
ァイアライトが生成し、熱間圧延時にデスケール性が劣
化しやすく、表面疵が疲労の起点となって疲労耐久性を
劣化させる場合がある。多量のＳｉは、電縫鋼管の溶接
性及び靭性にも悪影響を及ぼす。Hereinafter, the alloy components of the steel used in the present invention,
The content, production conditions, and the like will be described. C: An important alloy component for securing 0.03 to 0.10% by weight strength. The lower the C content, the better the ductility of the weld, but the lower the strength of the steel pipe. Therefore, in the present invention, the lower limit of the C content is set to 0.1.
It was set to 03% by weight. However, when a large amount of C exceeding 0.10% by weight is contained, a bainite or martensite structure is formed, and the workability and fatigue durability tend to be deteriorated. In addition, the heat affected zone is easily softened. Si: 0.20 to 1.0% by weight of a solid solution strengthening type alloy component. In the steel type having a reduced C content as in the present invention, at least 0.20% by weight or more for ensuring strength. is necessary. However, when a large amount of Si exceeding 1.0% by weight is included, firelite is generated during slab heating, descaleability is likely to be degraded during hot rolling, and surface flaws serve as a starting point of fatigue to reduce fatigue durability. May deteriorate. A large amount of Si adversely affects the weldability and toughness of the ERW pipe.
【０００９】Ｍｎ：１．０〜２．５重量％ 強度及び靭性を確保する上で不可欠な合金成分であり、
少なくとも１．０重量％以上のＭｎが必要である。しか
し、２．５重量％を超えるＭｎ含有は、靭性を劣化させ
るばかりでなく焼入れ性が強化され、溶接部の靭性を劣
化させ、溶接熱影響部では母材硬さより軟化することが
ある。Ｐ：０．０３重量％以下 溶接時の耐割れ性や靭性に悪影響を及ぼす成分であり、
本発明ではＰ含有量の上限を０．０３重量％に設定し
た。Ｓ：０．００５重量％以下 展伸したＭｎＳとなり、加工性及び靭性を劣化させる有
害元素である。特に、本発明のようにＭｎを添加した鋼
種にあっては、Ｍｎの効果を損わないためＳ含有量の上
限を０．００５重量％（好ましくは、０．００２重量
％）に規制する。 Mn: 1.0-2.5% by weight An alloy component indispensable for securing strength and toughness,
At least 1.0% by weight or more of Mn is required. However, if the Mn content exceeds 2.5% by weight, not only the toughness is deteriorated, but also the hardenability is enhanced, the toughness of the welded portion is deteriorated, and the weld heat affected zone may soften more than the base metal hardness. P: 0.03% by weight or less A component that has an adverse effect on crack resistance and toughness during welding,
In the present invention, the upper limit of the P content is set to 0.03% by weight. S: MnS expanded to 0.005% by weight or less and is a harmful element that deteriorates workability and toughness. Particularly, in the steel type to which Mn is added as in the present invention, the upper limit of the S content is regulated to 0.005% by weight (preferably 0.002% by weight) in order not to impair the effect of Mn.
【００１０】（Ｎ＋Ｏ）：１５０ｐｐｍ以下 Ｎは、ＴｉＮを形成し、溶接時の結晶粒の粗大化を抑制
する効果がある。しかし、多量のＮが含まれると、固溶
Ｎによる時効硬化が生じて靭性が劣化し、更にはＯが高
い場合には破壊の起点となる酸化物を生成する。そこ
で、本発明においては、（Ｎ＋Ｏ）を１５０ｐｐｍ以下
に設定した。Ｔｉ：０．０２〜０．２０重量％ ＴｉＮを生成し、溶接熱影響部の結晶粒を微細化する作
用を呈し、強度改善に有効な合金成分である。結晶粒の
微細化は、溶接熱影響部の靭性を向上させる上でも有効
である。このような効果は、０．０２重量％以上のＴｉ
添加で顕著になる。しかし、０．２０重量％を超える多
量のＴｉが含まれると、ＴｉＮが粗大化して溶接熱影響
部が硬化するため、靭性が劣化する。 (N + O): 150 ppm or less N forms TiN and has an effect of suppressing the coarsening of crystal grains during welding. However, when a large amount of N is contained, age hardening due to solid solution N occurs to deteriorate toughness, and further, when O is high, an oxide serving as a starting point of fracture is generated. Therefore, in the present invention, (N + O) is set to 150 ppm or less. Ti: 0.02 to 0.20% by weight TiN is produced, and has an effect of making the crystal grains of the weld heat affected zone finer, and is an effective alloy component for improving the strength. Refinement of crystal grains is also effective in improving the toughness of the heat affected zone. Such an effect can be obtained by using 0.02% by weight or more of Ti.
It becomes remarkable by addition. However, when a large amount of Ti exceeding 0.20% by weight is contained, TiN is coarsened and the heat affected zone is hardened, so that the toughness is deteriorated.
【００１１】Ｎｂ：０．０２〜０．１０重量％ Ｎｂ炭窒化物の生成によって結晶粒を微細化し、熱影響
部の軟化を抑制する重要な合金成分である。結晶粒の微
細化による軟化抑制効果及び母材の強度確保のために
は、０．０２重量％以上のＮｂが必要である。しかし、
０．１０重量％を超える過剰量のＮｂは、鋼材のコスト
を上昇させるばかりでなく、溶接性や靭性に悪影響を及
ぼす。Ｂ：０．００５０重量％以下 必要に応じて添加される合金成分であり、ごく微量の添
加で結晶粒界の歪みエネルギを低下させ、靭性を改善す
る作用を呈する。しかし、０．００５０重量％を超える
Ｂを添加すると、溶接時にベイナイト組織になり易く、
硬化する傾向がみられる。多量のＢ添加は、靭性にも悪
影響を及ぼす。 Nb: 0.02 to 0.10% by weight Nb is an important alloy component that refines crystal grains by forming Nb carbonitride and suppresses softening of the heat-affected zone. Nb of 0.02% by weight or more is required for the effect of suppressing softening due to the refinement of crystal grains and ensuring the strength of the base material. But,
An excessive amount of Nb exceeding 0.10% by weight not only increases the cost of the steel material but also adversely affects weldability and toughness. B: 0.0050% by weight or less An alloy component that is added as needed. When added in a very small amount, it has the effect of reducing the strain energy at the crystal grain boundaries and improving the toughness. However, if B is added in an amount exceeding 0.0050% by weight, a bainite structure is likely to occur during welding,
There is a tendency to harden. Addition of a large amount of B also has an adverse effect on toughness.
【００１２】Ｃｒ：０．３重量％以下 必要に応じて添加される合金成分であり、熱影響部の焼
戻し軟化抵抗を大きくし、炭化物を微細化する作用を呈
する。しかし、０．３重量％を超える多量のＣｒを添加
すると、バンド状組織になりやすく、焼入れ性が増大
し、溶接時に熱影響部の靭性が劣化する傾向がみられ
る。Ｃａ：０．００５０重量％以下 必要に応じて添加される合金成分であり、ＭｎＳ等の硫
化物系介在物の形態を制御する作用を呈する。Ｃａ添加
は、局部伸び及び靭性の向上にも有効に作用する。した
がって、高い加工性が要求される場合には、Ｃａを添加
することが好ましい。しかし、０．００５０重量％を超
えると、非金属介在物が増加して鋼材の清浄度が損わ
れ、溶接性も劣化する。トータルＡｌ：０．０１〜０．１重量％ Ａｌは、溶鋼の脱酸剤として使用される成分であり、Ｎ
を固定する作用をも呈する。このような作用は、０．０
１重量％以上のＡｌ添加で顕著になる。しかし、脱酸生
成物を含めた鋼中のＡｌ量がトータルで０．１重量％を
超えると、鋼材の清浄度が損われ、鋼板表面に疵が発生
しやすくなる。[0012] Cr: 0.3 wt% or less An alloy component added as necessary, and has an effect of increasing the tempering softening resistance of the heat-affected zone and miniaturizing carbides. However, when a large amount of Cr exceeding 0.3% by weight is added, a band-like structure is apt to be formed, the hardenability is increased, and the toughness of the heat-affected zone tends to deteriorate during welding. Ca: 0.0050% by weight or less Ca is an alloy component added as necessary, and has an effect of controlling the form of sulfide-based inclusions such as MnS. The addition of Ca effectively acts on local elongation and improvement of toughness. Therefore, when high workability is required, it is preferable to add Ca. However, when the content exceeds 0.0050% by weight, nonmetallic inclusions increase, so that the cleanliness of the steel material is impaired and the weldability is deteriorated. Total Al: 0.01 to 0.1% by weight Al is a component used as a deoxidizing agent for molten steel.
It also has the effect of fixing. Such an effect is 0.0
This becomes significant when Al is added in an amount of 1% by weight or more. However, if the total amount of Al in the steel, including the deoxidized product, exceeds 0.1% by weight, the cleanliness of the steel material is impaired, and flaws are likely to be generated on the steel sheet surface.
【００１３】スラブ加熱温度：１１５０〜１３００℃ 熱間圧延に先立って、Ｔｉ，Ｎｂ等の合金成分をマトリ
ックスに十分固溶させるため、１１５０℃以上の温度に
スラブを加熱する。しかし、１３００℃を超える高い加
熱温度では、結晶粒が粗大に成長して強度，靭性等の機
械的性質が劣化する。 Slab heating temperature: 1150-1300 ° C. Prior to hot rolling, the slab is heated to a temperature of 1150 ° C. or higher in order to sufficiently dissolve alloy components such as Ti and Nb in the matrix. However, at a high heating temperature exceeding 1300 ° C., crystal grains grow coarsely and mechanical properties such as strength and toughness deteriorate.
【００１４】熱間圧延：加熱されたスラブは、熱間圧延
工程においてトータル圧延率９０％以上で仕上げ圧延さ
れる。トータル圧延率９０％以上を確保することによ
り、強度向上に有効な細粒組織が熱延後に得られる。熱
間圧延の仕上げ温度は、Ａr3変態点〜Ａr3変態点＋１０
０℃の範囲に設定される。仕上げ温度がＡr3変態点未満
では、２相域で圧延されることになり、圧延条件が不安
定になりやすい。しかし、Ａr3変態点＋１００℃を超え
る仕上げ温度では、熱延後のオーステナイト粒が粗大化
し、熱延コイルで細粒組織が得られず強度が低下すると
共に、溶接時に熱影響部が軟化する。熱間圧延により得
られた鋼帯は、冷却速度１０〜５０℃／秒で冷却され、
４５０〜５５０℃で巻き取られる。 Hot rolling : The heated slab is finish-rolled at a total rolling reduction of 90% or more in a hot rolling step. By ensuring a total rolling reduction of 90% or more, a fine grain structure effective for improving strength can be obtained after hot rolling. The finishing temperature of the hot rolling is from the Ar3 transformation point to the Ar3 transformation point +10.
It is set in the range of 0 ° C. If the finishing temperature is lower than the Ar3 transformation point, rolling is performed in the two-phase region, and rolling conditions are likely to be unstable. However, at a finishing temperature exceeding the Ar 3 transformation point + 100 ° C., austenite grains after hot rolling become coarse, a fine-grained structure cannot be obtained in a hot-rolled coil, strength is reduced, and the heat-affected zone is softened during welding. The steel strip obtained by hot rolling is cooled at a cooling rate of 10 to 50 ° C./sec.
Wound at 450-550 ° C.
【００１５】熱延後の冷却速度は、金属組織を制御する
ために重要なファクタであり、１０℃／秒未満の冷却速
度ではフェライト変態が進行して軟質化し、必要な強度
が得られない。逆に５０℃／秒を超える冷却速度では、
熱延鋼帯の組織にベイナイト，マルテンサイト等が含ま
れやすくなる。ベイナイト，マルテンサイト等の組織
は、鋼板の材質変動を大きくし、電縫溶接や他部品との
溶接接合時に熱影響部の軟化の程度を高くする原因とな
る。熱延鋼帯は、微細フェライトと微細パーライトとの
混合組織となるように４５０〜５５０℃で巻き取られ
る。巻取り温度が４５０℃を下回ると、ベイナイトやマ
ルテンサイト組織になり易く、電縫溶接等の溶接熱影響
部が著しく軟化し、スタビライザとして使用する際に軟
化部分に応力集中が発生し、結果的に耐久性が劣化する
ことになる。逆に、５５０℃を超える巻取り温度では、
粗大なフェライト＋パーライト組織となって必要な強度
が得られず、疲労耐久性を劣化させる。[0015] The cooling rate after hot rolling is an important factor for controlling the metallographic structure. At a cooling rate of less than 10 ° C / sec, the ferrite transformation proceeds to soften and the required strength cannot be obtained. Conversely, at cooling rates exceeding 50 ° C./sec,
Bainite, martensite, etc. are likely to be included in the structure of the hot-rolled steel strip. The structure of bainite, martensite, and the like causes a large change in the material of the steel sheet and causes a high degree of softening of the heat-affected zone at the time of electric resistance welding or welding and joining with other parts. The hot-rolled steel strip is wound at 450 to 550 ° C. so as to have a mixed structure of fine ferrite and fine pearlite. When the winding temperature is lower than 450 ° C, bainite or martensite structure is easily formed, and the heat affected zone of welding such as electric resistance welding is softened remarkably, and stress concentration occurs in the softened portion when used as a stabilizer. In this case, the durability is deteriorated. Conversely, at winding temperatures above 550 ° C,
A coarse ferrite + pearlite structure is not obtained, and the required strength cannot be obtained, deteriorating fatigue durability.
【００１６】熱間圧延工程では、９００〜１１００℃の
温度域でデスケーラ吐出圧力２００ｋｇｆ／ｃｍ2 以上
のデスケールを少なくとも１パス以上行うことが好まし
い。デスケーラ吐出圧力を２００ｋｇｆ／ｃｍ2 以上と
設定することにより、鋼帯表面からスケールが効率よく
除去され、表面性状の良好な熱延鋼帯が得られる。２０
０ｋｇｆ／ｃｍ2 未満のデスケーラ吐出圧力では、デス
ケールが不充分になり、表面に残存するスケールがその
後の熱延で鋼帯表面に押し込まれ、鋼管における疲労破
壊の起点となる凹凸が鋼帯表面に形成されやすい。高い
デスケーラ吐出圧力による高圧デスケールにおいても、
デスケール温度を適正に設定することによって効率の良
いデスケールが可能になる。デスケール温度が９００℃
を下回ると、デスケール性が劣り、表面に残存するスケ
ールで熱延鋼帯の表面性状が劣化し、最終的に鋼管とし
た場合に疲労耐久性が劣化する。逆に１１００℃を超え
るデスケール温度では、熱延における熱効率が悪く、エ
ッジ部の急激な温度低下によりエッジ割れが発生しやす
くなる。In the hot rolling step, descaling at a descaler discharge pressure of 200 kgf / cm 2 or more is preferably performed in at least one pass in a temperature range of 900 to 1100 ° C. By setting the descaler discharge pressure to 200 kgf / cm 2 or more, scale is efficiently removed from the surface of the steel strip, and a hot-rolled steel strip having good surface properties can be obtained. 20
At a descaler discharge pressure of less than 0 kgf / cm 2 , the descaling becomes insufficient, the scale remaining on the surface is pushed into the steel strip surface by the subsequent hot rolling, and irregularities that become the starting point of fatigue fracture in the steel pipe are formed on the steel strip surface. Easy to be formed. Even in high pressure descale due to high descaler discharge pressure,
By setting the descaling temperature appropriately, efficient descaling becomes possible. Descale temperature is 900 ℃
If it is less than, the descalability is inferior, the surface properties of the hot-rolled steel strip are deteriorated by the scale remaining on the surface, and the fatigue durability is deteriorated when finally formed into a steel pipe. Conversely, at a descale temperature exceeding 1100 ° C., the thermal efficiency in hot rolling is poor, and edge cracks are likely to occur due to a sharp drop in temperature at the edge.
【００１７】電縫溶接後の熱処理：熱延鋼帯は、酸洗後
に電縫溶接によって造管される。電縫鋼管は、肉厚を
Ｔ，外径をＤとしたとき、疲労耐久性を向上させるため
肉厚外径比Ｔ／Ｄを０．０７〜０．１５の範囲に設定す
ることが好ましい。肉厚外径比Ｔ／Ｄが小さいほど、肉
厚が薄く外径の大きな電縫鋼管となる。肉厚を薄くする
ことは軽量化の要求が強い車両搭載部品として好適であ
るが、肉厚外径比Ｔ／Ｄが０．０７を下回ると中空スタ
ビライザとしての耐久性が確保できない場合がある。逆
に０．１５を超える肉厚外径比Ｔ／Ｄで造管すること
は、軽量化に反して棒鋼に近くなり、また厚肉小径とな
って電縫鋼管の表面に残留する引張り応力が耐久性を劣
化させる傾向が現れる。 Heat treatment after ERW : Hot-rolled steel strip is formed by ERW after pickling. When the thickness of the ERW steel pipe is T and the outer diameter is D, it is preferable to set the thickness outer diameter ratio T / D in the range of 0.07 to 0.15 in order to improve fatigue durability. The smaller the thickness outer diameter ratio T / D is, the smaller the wall thickness is and the larger the outer diameter is an ERW steel pipe. Reducing the wall thickness is suitable as a vehicle-mounted component for which there is a strong demand for weight reduction, but if the wall thickness / outside diameter ratio T / D is less than 0.07, durability as a hollow stabilizer may not be secured in some cases. Conversely, forming a pipe with a wall thickness ratio T / D exceeding 0.15 is close to that of a steel bar in spite of the weight reduction, and the tensile stress remaining on the surface of the electric resistance welded steel pipe due to the thin wall diameter becomes small. A tendency to deteriorate durability appears.
【００１８】電縫溶接を経た溶接部近傍は、高温への加
熱と急速な冷却を受けているため、溶接のままでは粗大
なマルテンサイト組織になっており、耐久性が著しく低
い。そこで、電縫溶接後に一旦Ｍs 点以下に冷却してマ
ルテンサイト変態させた後、直ちに連続して高周波加熱
して電縫溶接部を焼き戻し、著しく硬化した電縫溶接部
近傍を回復させる。Ａc1変態点―７０℃以下の温度で焼
き戻すと、回復が不充分で、スタビライザへの曲げ加工
に支障をきたす。しかし、Ａc1変態点を超える温度に加
熱すると、再度オーステナイト化し、焼戻し後の冷却過
程で再びマルテンサイトが生じて硬化する。Since the vicinity of the welded portion after the electric resistance welding has been heated to a high temperature and rapidly cooled, the as-welded portion has a coarse martensitic structure and has extremely low durability. Therefore, after once by martensite transformation is cooled below M s point after electric resistance welding, tempering the electric resistance welding portion by high-frequency heating immediately in succession, to recover the electric resistance welding vicinity cured significantly. When tempered at transformation point A c1 -70 ° C. a temperature below insufficient recovery, hinder the bending of the stabilizer. However, when heated to a temperature exceeding the A c1 transformation point, austenite is formed again, and martensite is generated again in the cooling process after tempering to harden.
【００１９】[0019]
【実施例】表１に掲げた各種鋼材のスラブを常法に従っ
て製造し、表２の熱延条件で熱延鋼帯にした。粗圧延後
の仕上げ圧延前に、デスケーラ吐出圧力１００，１６
０，２５０ｋｇｆ／ｃｍ2 で高圧水を用いてデスケール
し、巻取り温度を４００〜６００℃の範囲で変化させ
た。EXAMPLES Slabs of various steel materials listed in Table 1 were manufactured according to a conventional method, and were formed into hot-rolled steel strips under the hot-rolling conditions shown in Table 2. Before rough rolling and before finish rolling, the descaler discharge pressure should be 100, 16
Descaling was performed using high-pressure water at 0.250 kgf / cm 2 , and the winding temperature was changed in the range of 400 to 600 ° C.
【００２０】 [0020]
【００２１】 [0021]
【００２２】各熱延鋼帯をスリットし、高周波電縫溶接
で外径２１．０ｍｍ，肉厚２．６ｍｍ（肉厚外径比Ｔ／
Ｄ＝０．１２３）の鋼管に造管し、直ちに高周波加熱し
て電縫溶接部を６８０℃に焼き戻した。得られた各電縫
溶接鋼管を、曲げ試験，電縫溶接時の熱影響部の軟化の
有無，硬度差（ΔＨＶ：ＨＶmax −ＨＶmin ），偏平試
験，ねじり疲労試験で評価した。ねじり疲労限は、１×
１０7 サイクルで破断しない応力とした。引張強さ：６
９０〜１１００Ｎ／ｍｍ2 ，電縫溶接部の硬さ：軟化の
有無及び硬さΔＨＶ≦４０，スタビライザの加工性とし
て曲げ試験：９０度２Ｄ曲げで電縫溶接部にわれが生じ
ないこと，偏平試験：８ｍｍ以下，衝撃靭性としてー６
０℃における衝撃：エネルギ１１２０Ｎ・ｍでアール２
５ｍｍのポンチを落下させたときに折損しないこと、疲
労特性としてネジリ疲労試験による疲労限：４００Ｎ／
ｍｍ2 以上を合格基準と設定した。各電縫溶接鋼管の評
価結果を表３に示す。Each hot-rolled steel strip was slit, and the outer diameter was 21.0 mm and the wall thickness was 2.6 mm by high frequency electric resistance welding (wall thickness outer diameter ratio T /
D = 0.123) and immediately heated by high frequency to temper the ERW weld to 680 ° C. The resulting respective electric resistance welding steel pipe, bending test, the presence or absence of softening of the heat affected zone during electric resistance welding, the hardness difference (ΔHV: HV max -HV min) , was evaluated by flattening test, torsion fatigue test. The torsional fatigue limit is 1 ×
Was the stress that does not break at 10 7 cycles. Tensile strength: 6
90 to 1100 N / mm 2 , Hardness of ERW weld: presence or absence of softening and hardness ΔHV ≦ 40, Bending test as workability of stabilizer: No cracking in ERW weld at 90 ° 2D bending, flatness Test: 8mm or less, impact toughness is -6
Impact at 0 ° C: 2 at energy of 1120 Nm
No breakage when a 5 mm punch is dropped. Fatigue limit: 400 N /
mm 2 or more was set as a passing criterion. Table 3 shows the results of the evaluation of each electric resistance welded steel pipe.
【００２３】 [0023]
【００２４】試験番号１〜１４は、何れも本発明で規定
した成分条件を満足する鋼種Ａ〜Ｅを使用している。し
かし、試験番号２は、スラブの加熱温度が低く、Ｔｉ，
Ｎｂの固溶が不充分なため、電縫溶接部の硬度差ΔＨＶ
が大きくなり、アーク溶接時の硬度差ΔＨＶも大きくな
っていた。逆にスラブの加熱温度が高い試験番号４で
も、電縫溶接部の硬度差ΔＨＶが大きくなり、アーク溶
接時の硬度差ΔＨＶも大きくなっていた。試験番号７で
使用した鋼種ＣのＡr3変態点は８４５℃であるが、仕上
げ温度が９５０℃とＡr3変態点＋１００℃を超えるた
め、電縫溶接部の硬度差ΔＨＶが大きくなり、アーク溶
接時の硬度差ΔＨＶも大きくなっていた。Test Nos. 1 to 14 all use steel types A to E satisfying the component conditions specified in the present invention. However, in Test No. 2, the heating temperature of the slab was low and Ti,
Since the solid solution of Nb is insufficient, the hardness difference ΔHV
And the hardness difference ΔHV during arc welding also increased. Conversely, even in Test No. 4 where the slab heating temperature was high, the hardness difference ΔHV of the electric resistance welded portion was large, and the hardness difference ΔHV at the time of arc welding was also large. A r3 transformation point of steel grade C used in Test No. 7 is a 845 ° C., since the finishing temperature exceeds 950 ° C. and A r3 transformation temperature + 100 ° C., the greater the hardness difference ΔHV ERW weld, arc welding The hardness difference ΔHV at the time was also large.
【００２５】デスケーラ吐出圧力が２５０ｋｇｆ／ｍｍ
2 と高い試験番号９は、ねじり疲労において、デスケー
ラ吐出圧力１００ｋｇｆ／ｍｍ2 で製造した試験番号１
０に比較してねじり疲労限が更に向上した。トータル圧
下率が低い試験番号１１では、電縫溶接部の硬度差ΔＨ
Ｖが大きく、ねじり疲労限も低い値を示した。また。曲
げによって加工割れも発生し、アーク溶接時の硬度差Δ
ＨＶも大きくなっていた。試験番号１２は、巻取り温度
が高く、冷却速度が遅いため結晶粒径が大きくなり、ね
じり疲労限が低い値を示した。他方、巻取り温度が低く
冷却速度が速い試験番号１３は、ベイナイト組織にな
り、電縫溶接部の硬度差ΔＨＶが大きくなり、アーク溶
接時の硬度差ΔＨＶも大きくなっていた。また、曲げに
よる加工割れも発生した。The discharge pressure of the descaler is 250 kgf / mm
2 high Test No. 9, the torsion fatigue test numbers were prepared by the descaler discharge pressure 100 kgf / mm 2 1
As compared with 0, the torsional fatigue limit was further improved. In Test No. 11 having a low total draft, the hardness difference ΔH
V was large and the torsional fatigue limit was also low. Also. Work cracking also occurs due to bending, the hardness difference during arc welding Δ
HV was also getting bigger. In Test No. 12, the winding temperature was high and the cooling rate was low, so that the crystal grain size was large and the torsional fatigue limit was low. On the other hand, in Test No. 13 in which the winding temperature was low and the cooling rate was high, a bainite structure was formed, the hardness difference ΔHV of the electric resistance welded portion was increased, and the hardness difference ΔHV during arc welding was also increased. In addition, processing cracks due to bending also occurred.
【００２６】試験番号１５〜２１は、本発明で規定した
成分条件を外れる鋼種Ｆ〜Ｋを使用した例である。試験
番号１５は、Ｎｂ含有量の高い鋼種Ｆを使用したため、
ＨＶmax が高くなり、電縫溶接部の硬度差ΔＨＶが大き
くなっている。また、アーク溶接時の硬度差ΔＨＶも大
きく、曲げによる加工割れも発生した。他方、Ｔｉ，Ｎ
ｂを添加していない鋼種Ｇを用いた試験番号１６，１７
では、電縫溶接部及びアーク溶接部の硬度差ΔＨＶが大
きく、疲労限も低い値を示した。Test Nos. 15 to 21 are examples using steel grades F to K which deviate from the component conditions specified in the present invention. Test No. 15 used steel type F having a high Nb content,
HV max is increased, and the hardness difference ΔHV of the electric resistance welded portion is increased. Further, the hardness difference ΔHV at the time of arc welding was large, and a work crack due to bending occurred. On the other hand, Ti, N
Test Nos. 16 and 17 using steel type G to which b was not added
In Example 2, the hardness difference ΔHV between the electric resistance welded portion and the arc welded portion was large, and the fatigue limit was low.
【００２７】Ｓ，Ｔｉ，Ｃａを多量に含む鋼種Ｈを使用
した試験番号１８では曲げ加工性，偏平試験，低温靭性
に劣り、Ｃ量が不足する鋼種Ｉを使用した試験番号１９
では引張強さ及びねじり疲労限が低い値を示した。他
方、多量のＣを含む鋼種Ｊを使用した試験番号２０は、
電縫溶接部の硬度差ΔＨＶが大きく、曲げによる加工割
れが発生し、低温衝撃試験でも折損した。また、アーク
溶接部はＨmax が高く、硬度差ΔＨＶが大きくなった。
多量のＳｉ，Ｍｎ，Ｃｒを含む鋼種Ｋを使用した試験番
号２１では、電縫溶接部の硬度差ΔＨＶが大きく、曲げ
による加工割れが発生した。また、低温衝撃試験でも折
損し、アーク溶接時の硬度差ΔＨＶも大きくなってい
た。Test No. 18 using steel type H containing a large amount of S, Ti and Ca is test number 19 using steel type I which is inferior in bending workability, flatness test and low temperature toughness and lacks C content.
Showed low values of the tensile strength and the torsional fatigue limit. On the other hand, test number 20 using steel type J containing a large amount of C
The hardness difference ΔHV of the ERW welded portion was large, and a work crack due to bending occurred, and it was broken even in a low-temperature impact test. Further, the arc welding unit has a high H max, hardness difference ΔHV is increased.
In Test No. 21 using steel type K containing a large amount of Si, Mn, and Cr, the hardness difference ΔHV of the electric resistance welded portion was large, and a work crack due to bending occurred. In addition, it was broken in the low-temperature impact test, and the hardness difference ΔHV at the time of arc welding was large.
【００２８】これに対し、本発明で規定した成分条件及
び製造条件を満足する試験番号１，３，５，６，８，
９，１４は、何れも微細なフェライト＋パーライト組織
となり、電縫溶接部及びアーク溶接部の硬度差ΔＨＶが
小さく、ねじり疲労限も４００Ｎ／ｍｍ2 以上と高い値
を示した。鋼種Ｃ（本発明例）及び鋼種Ｇ（比較例）を
用いた電縫鋼管の電縫溶接部を６８０℃に高周波加熱し
て焼戻し、硬さを測定したところ、それぞれ図１に示す
硬度分布をもっていた。On the other hand, Test Nos. 1, 3, 5, 6, 8, and 9 satisfying the component conditions and production conditions specified in the present invention.
Samples Nos. 9 and 14 each had a fine ferrite + pearlite structure, a small hardness difference ΔHV between the electric resistance welded portion and the arc welded portion, and a high torsional fatigue limit of 400 N / mm 2 or more. When the ERW welded portion of the ERW steel pipe using the steel type C (Example of the present invention) and the steel type G (Comparative Example) was tempered by high-frequency heating to 680 ° C. and the hardness was measured, the hardness distribution was as shown in FIG. Was.
【００２９】次いで、本発明で規定した製造条件で鋼種
Ｃから外径，肉厚が異なる電縫溶接鋼管を製造し、電縫
溶接部を高周波焼戻し処理した。焼戻し温度は、６１０
〜６９０℃の範囲で変化させた。焼戻し処理された電縫
鋼管について、機械的性質を同様に調査した。Next, ERW welded steel pipes having different outer diameters and wall thicknesses were manufactured from steel type C under the production conditions specified in the present invention, and the ERW welded parts were subjected to induction tempering. Tempering temperature is 610
The temperature was varied in the range of ６690 ° C. The mechanical properties of the tempered electric resistance welded steel pipe were similarly examined.
【００３０】 [0030]
【００３１】表４の調査結果にみられるように、焼戻し
温度が低い試験番号２２では、電縫溶接部の硬度差ΔＨ
Ｖが高くなり、曲げによる加工割れが発生し、低温衝撃
試験でも折損した。逆に焼戻し温度がＡr3点を超える試
験番号２３では、電縫溶接部が再度部分的にオーステナ
イト化して焼入れ処理と同様な状態になったため、一部
マルテンサイト組織となり、電縫溶接部の最大硬さＨＶ
max が高くなった。そのため、電縫溶接部の硬度差ΔＨ
Ｖが大きくなり、曲げによる加工割れが発生し、低温衝
撃試験でも折損した。焼戻し処理を施さない試験番号２
４では、電縫溶接部の硬度差ΔＨＶが大きく、曲げによ
る加工割れが発生し、低温衝撃試験でも折損した。As can be seen from the investigation results in Table 4, in Test No. 22 where the tempering temperature is low, the hardness difference ΔH
V increased, and processing cracks occurred due to bending, and breakage occurred in a low-temperature impact test. Conversely, in Test No. 23, in which the tempering temperature exceeds the Ar3 point, the ERW weld was partially austenitized again and was in a state similar to that of the quenching treatment, so that part of the ERW weld became a martensitic structure, and Hardness HV
max is now higher. Therefore, the hardness difference ΔH of the electric resistance welded portion
V became large, and processing cracks occurred due to bending, and breakage occurred even in a low-temperature impact test. Test number 2 without tempering
In No. 4, the hardness difference ΔHV of the electric resistance welded portion was large, and a work crack due to bending occurred, and it was broken even in a low-temperature impact test.
【００３２】これに対し、電縫溶接部を６８５℃に焼き
戻した試験番号２５は、４５０Ｎ／ｍｍ2 を超える高い
疲労限を示し、疲労耐久性が良好であることが判った。
ただし、試験番号２５の電縫鋼管は、表３の試験番号６
（肉厚外径比Ｔ／Ｄ：０．１２３）に比較して肉厚外径
比Ｔ／Ｄが０．０６３と低いことから、若干低い値のね
じり疲労限を示した。焼戻し温度を６９０℃に設定した
試験番号２６も、４００Ｎ／ｍｍ２を超える高い疲労限
を示したが、試験番号６と比較するとねじり疲労限の値
は若干低くなっていた。On the other hand, Test No. 25 in which the electric resistance welded portion was tempered to 685 ° C. showed a high fatigue limit exceeding 450 N / mm 2 , indicating that the fatigue durability was good.
However, the ERW steel pipe with test number 25 is the same as test number 6 in Table 3.
Since the thickness / outside diameter ratio T / D was as low as 0.063 as compared with (thickness / outside diameter ratio T / D: 0.123), the torsional fatigue limit was slightly lower. Test No. 26 in which the tempering temperature was set to 690 ° C. also showed a high fatigue limit exceeding 400 N / mm 2, but the value of the torsional fatigue limit was slightly lower than that of Test No. 6.
【００３３】また、鋼種Ｃから作られた試験番号６の電
縫鋼管（本発明例）及び鋼種Ｇから作られた試験番号１
７の電縫鋼管（比較例）に電流２５０Ａ，電圧２５Ｖ，
溶接速度５０ｃｍ／分，ワイヤＭＧＳ８０（径１．２ｍ
ｍ）の溶接条件で他部品として同じ鋼管をアーク溶接し
た。そして、アーク溶接後の電縫鋼管の硬さを測定し
た。その結果、図２に示すように比較例の電縫鋼管では
溶接部と母材部との硬度差が大きくなっていたのに対
し、本発明例の電縫鋼管では硬度差ΔＨＶが２８の範囲
に収まっていた。An ERW steel pipe of test number 6 made of steel type C (example of the present invention) and test number 1 made of steel type G
The current of 250A, the voltage of 25V,
Welding speed 50cm / min, wire MGS80 (diameter 1.2m)
Under the welding conditions of m), the same steel pipe as another part was arc-welded. Then, the hardness of the ERW steel pipe after the arc welding was measured. As a result, as shown in FIG. 2, the hardness difference between the welded portion and the base metal portion was large in the ERW steel tube of the comparative example, whereas the hardness difference ΔHV was in the range of 28 in the ERW steel tube of the present invention. It was in.
【００３４】[0034]
【発明の効果】以上に説明したように、本発明は、低Ｃ
化して加工性を確保すると共に、Ｔｉ，Ｎｂの炭窒化物
生成及び細粒化効果を活用して溶接熱影響部の軟化及び
効果を抑制し、成分条件及び製造条件を適正化すること
により、電縫溶接鋼管の疲労耐久性を改善している。こ
の電縫鋼管は、高価なＭｏ，Ｖ等の合金成分の添加を必
要とせず、しかも従来のＳ４５Ｃ，ＳＵＰ６等に比較し
て熱処理も不要であるため、低コストで疲労耐久性に優
れた中空スタビライザとして使用される。また、他部品
と溶接した場合に溶接部の硬さ変動が少なく、均一化す
ることによって疲労破壊寿命が延長する。As described above, the present invention has a low C content.
In addition to securing the workability by reducing the effect of carbonitride generation and grain refinement of Ti and Nb, the softening and effect of the weld heat affected zone are suppressed, and the component conditions and manufacturing conditions are optimized. Improves the fatigue durability of ERW welded steel pipes. This electric resistance welded steel pipe does not require the addition of expensive alloy components such as Mo and V, and does not require heat treatment as compared with conventional S45C, SUP6, etc., so that the hollow pipe having low cost and excellent fatigue durability is used. Used as a stabilizer. In addition, when welding with other parts, the hardness variation of the welded portion is small, and the uniformity extends the fatigue fracture life.
【図１】 ６８０℃に焼き戻した電縫溶接部を中心とす
る電縫鋼管の硬度分布FIG. 1 Hardness distribution of ERW steel pipe centered on ERW welded parts tempered to 680 ° C.
【図２】 アーク溶接部を中心とした電縫鋼管の硬度分
布Fig. 2 Hardness distribution of ERW steel pipe centered on arc welded part
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 4K032 AA01 AA02 AA04 AA08 AA11 AA16 AA17 AA21 AA22 AA26 AA27 AA29 AA31 AA35 BA03 CA02 CA03 CB02 CC03 CC04 CD03 CE01 CF02 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 4K032 AA01 AA02 AA04 AA08 AA11 AA16 AA17 AA21 AA22 AA26 AA27 AA29 AA31 AA35 BA03 CA02 CA03 CB02 CC03 CC04 CD03 CE01 CF02
Claims (4)
０．２０〜１．０重量％，Ｍｎ：１．０〜２．５重量
％，Ｐ：０．０３重量％以下，Ｓ：０．００５重量％以
下，（Ｎ＋Ｏ）：１５０ｐｐｍ以下，Ｔｉ：０．０２〜
０．２０重量％，Ｎｂ：０．０２〜０．１０重量％，ト
ータルＡｌ：０．０１〜０．１重量％，残部が実質的に
Ｆｅの組成をもつスラブを１１５０〜１３００℃に加熱
した後、仕上げ圧延でのトータル圧延率：９０％以上，
仕上げ温度：Ａr3変態点〜Ａr3変態点＋１００℃の温度
域で熱間圧延し、冷却速度１０〜５０℃／秒で冷却し、
巻取り温度４５０〜５５０℃で巻き取って熱延コイルと
し、該熱延コイルを酸洗後に電縫鋼管とする際、電縫溶
接部の冷却後に連続して高周波加熱により電縫溶接部を
Ａc1変態点〜Ａc1変態点−７０℃の温度域で焼き戻すこ
とを特徴とする疲労耐久性に優れた中空スタビライザ用
高強度鋼管の製造方法。1. C: 0.03 to 0.10% by weight, Si:
0.20 to 1.0% by weight, Mn: 1.0 to 2.5% by weight, P: 0.03% by weight or less, S: 0.005% by weight or less, (N + O): 150ppm or less, Ti: 0 .02-
A slab having a composition of 0.20 wt%, Nb: 0.02 to 0.10 wt%, total Al: 0.01 to 0.1 wt%, and the balance substantially Fe was heated to 1150 to 1300 ° C. Later, the total rolling rate in finish rolling: 90% or more,
Finishing temperature: hot-rolled in a temperature range of A r3 transformation point to A r3 transformation point + 100 ° C., then cooled at a cooling rate of 10 to 50 ° C. / sec,
When the hot-rolled coil is taken up at a temperature of 450 to 550 ° C. to form a hot-rolled coil, and the hot-rolled coil is pickled to form an ERW steel pipe, the ERW weld is continuously cooled by high-frequency heating to form an ARW weld. A method for producing a high-strength steel pipe for a hollow stabilizer excellent in fatigue durability, characterized by tempering in a temperature range of c1 transformation point to A c1 transformation point -70 ° C.
ｒ：０．３重量％以下，Ｃａ：０．００５０重量％以下
の１種又は２種以上を含むスラブを使用する請求項１記
載の疲労耐久性に優れた中空スタビライザ用高強度鋼管
の製造方法。2. B: 0.0050% by weight or less, C:
2. The method for producing a high-strength steel pipe for a hollow stabilizer excellent in fatigue durability according to claim 1, wherein a slab containing one or more of r: 0.3% by weight or less and Ca: 0.0050% by weight or less is used. .
度域でデスケーラ吐出圧力２００ｋｇｆ／ｃｍ2 以上の
デスケールを少なくとも１パス以上行うことを特徴とす
る請求項１又は２記載の疲労耐久性に優れた中空スタビ
ライザ用高強度鋼管の製造方法。3. The fatigue durability according to claim 1, wherein at the time of hot rolling, at least one pass of descaling at a discharge pressure of 200 kgf / cm 2 or more is performed in a temperature range of 900 to 1100 ° C. Manufacturing method of high strength steel pipe for hollow stabilizer.
〜０．１５である請求項１〜３記載の何れかに記載の疲
労耐久性に優れた中空スタビライザ用高強度鋼管の製造
方法。4. An ERW steel pipe having a thickness outer diameter ratio T / D of 0.07.
The method for producing a high-strength steel pipe for a hollow stabilizer excellent in fatigue durability according to any one of claims 1 to 3, which is 0.15 to 0.15.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29660698A JP4055920B2 (en) | 1998-10-19 | 1998-10-19 | Manufacturing method of high strength steel pipe for hollow stabilizer with excellent fatigue durability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP29660698A JP4055920B2 (en) | 1998-10-19 | 1998-10-19 | Manufacturing method of high strength steel pipe for hollow stabilizer with excellent fatigue durability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2000119750A true JP2000119750A (en) | 2000-04-25 |
| JP4055920B2 JP4055920B2 (en) | 2008-03-05 |
Family
ID=17835740
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP29660698A Expired - Lifetime JP4055920B2 (en) | 1998-10-19 | 1998-10-19 | Manufacturing method of high strength steel pipe for hollow stabilizer with excellent fatigue durability |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002070767A1 (en) * | 2001-03-07 | 2002-09-12 | Nippon Steel Corporation | Electric welded steel tube for hollow stabilizer |
| JP2009127119A (en) * | 2007-11-28 | 2009-06-11 | Nissan Motor Co Ltd | Resistance-welded steel plate |
| GB2433746B (en) * | 2005-12-27 | 2009-07-01 | Kobe Steel Ltd | Steel sheet having excellent weldability |
| JP2010090442A (en) * | 2008-10-08 | 2010-04-22 | Jfe Steel Corp | High workability and high strength steel pipe having excellent chemical treatment property and method for producing the same |
| JP2010089127A (en) * | 2008-10-08 | 2010-04-22 | Jfe Steel Corp | Working method of member excellent in chemical conversion property |
-
1998
- 1998-10-19 JP JP29660698A patent/JP4055920B2/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2002070767A1 (en) * | 2001-03-07 | 2002-09-12 | Nippon Steel Corporation | Electric welded steel tube for hollow stabilizer |
| US7048811B2 (en) | 2001-03-07 | 2006-05-23 | Nippon Steel Corporation | Electric resistance-welded steel pipe for hollow stabilizer |
| GB2433746B (en) * | 2005-12-27 | 2009-07-01 | Kobe Steel Ltd | Steel sheet having excellent weldability |
| US9085816B2 (en) | 2005-12-27 | 2015-07-21 | Kobe Steel, Ltd. | Steel sheet having excellent weldability |
| JP2009127119A (en) * | 2007-11-28 | 2009-06-11 | Nissan Motor Co Ltd | Resistance-welded steel plate |
| JP2010090442A (en) * | 2008-10-08 | 2010-04-22 | Jfe Steel Corp | High workability and high strength steel pipe having excellent chemical treatment property and method for producing the same |
| JP2010089127A (en) * | 2008-10-08 | 2010-04-22 | Jfe Steel Corp | Working method of member excellent in chemical conversion property |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4055920B2 (en) | 2008-03-05 |
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