JP3111861B2 - Manufacturing method of high-tensile-resistance electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance - Google Patents
Manufacturing method of high-tensile-resistance electric resistance welded steel pipe excellent in hydrogen delayed cracking resistanceInfo
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- JP3111861B2 JP3111861B2 JP07201173A JP20117395A JP3111861B2 JP 3111861 B2 JP3111861 B2 JP 3111861B2 JP 07201173 A JP07201173 A JP 07201173A JP 20117395 A JP20117395 A JP 20117395A JP 3111861 B2 JP3111861 B2 JP 3111861B2
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- resistance
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- delayed cracking
- steel
- hydrogen delayed
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、自動車のドアイン
パクトビームなどに用いられる高張力電縫鋼管の製造方
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 ERW steel pipe used for a door impact beam of an automobile or the like.
【０００２】[0002]
【従来の技術】自動車などの車両ドア内部には、安全性
の観点からドアインパクトビームと呼ばれる補強材が設
けられている。従来のドアインパクトビームには、高張
力冷延鋼板のプレス成形品が用いられることが多かった
が、近年、軽量化のために、引張強度が９８０Ｎ／ｍｍ
2 以上の著しく強度の高い高張力電縫鋼管が採用される
ようになってきた。2. Description of the Related Art A reinforcing member called a door impact beam is provided inside a vehicle door of an automobile or the like from the viewpoint of safety. For the conventional door impact beam, a press-formed product of a high-tensile cold-rolled steel sheet is often used. However, in recent years, in order to reduce the weight, a tensile strength of 980 N / mm has been used.
Two or more high-strength, high-strength ERW steel pipes have been adopted.
【０００３】しかし、著しく強度が高く、しかも造管に
より残留歪みが付加される高張力電縫鋼管をドアインパ
クトビームに用いる場合、ドア内部で腐食が進行すると
鋼中に水素が侵入し鋼が破壊されるいわゆる「水素遅れ
割れ」が生じる恐れがある。[0003] However, when a high-strength ERW steel pipe, which has extremely high strength and is subjected to residual strain due to pipe making, is used for a door impact beam, as corrosion progresses inside the door, hydrogen penetrates into the steel and the steel is destroyed. So-called “hydrogen delayed cracking” may occur.
【０００４】これまで、著しく強度の高い熱延鋼板や冷
延鋼板を用いた高張力電縫鋼管やその製造方法について
は、特開平１ー２０５０３２号公報、特開平４ー１３１
３２７号公報、特開平４ー１８７３１９号公報、特開平
６ー８８１２９号公報などで紹介されている。[0004] Hitherto, a high-tensile ERW pipe using a hot-rolled steel sheet or a cold-rolled steel sheet having extremely high strength and a method of manufacturing the same have been disclosed in JP-A-1-205032 and JP-A-4-131.
327, JP-A-4-187319, JP-A-6-88129, and the like.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、いずれ
も「水素遅れ割れ」に対する考慮がなされていない。However, no consideration has been given to "hydrogen delayed cracking".
【０００６】本発明は、このような課題を解決するため
になされたものであり、引張強度が９８０Ｎ／ｍｍ2 以
上で、しかも耐水素遅れ割れ特性に優れた高張力電縫鋼
管の製造方法を提供することを目的とする。The present invention has been made in order to solve such problems, and a method of manufacturing a high tensile strength electric resistance welded steel pipe having a tensile strength of 980 N / mm 2 or more and having excellent resistance to hydrogen delayed cracking is provided. The purpose is to provide.
【０００７】[0007]
【課題を解決するための手段】本発明者等は、耐水素遅
れ割れ特性に優れた高張力電縫鋼管の製造方法について
鋭意検討した結果、鋼成分、熱延条件および造管条件を
適性化することにより上記課題が解決されるという知見
を見出した。Means for Solving the Problems The present inventors have conducted intensive studies on a method of manufacturing a high tensile strength electric resistance welded steel pipe having excellent resistance to hydrogen delayed cracking. As a result, the steel composition, hot rolling conditions and pipe forming conditions have been optimized. It has been found that the above-mentioned problem can be solved by doing.
【０００８】すなわち、請求項１に記載の第１の発明
は、ｗｔ％で、Ｃ：０．１〜０．１９、Ｓｉ：０．０１
〜０．５、Ｍｎ：０．８〜１．６、Ｃｒ：０．０５〜
０．６、Ａｌ：０．０１〜０．０６、Ｐ：０．０２以下
（０を含む）、Ｓ：０．００３以下（０を含む）、Ｎ：
０．００５以下（０を含む）、Ｔｉ：０．０１５以下
（０を含む）、Ｂ：０．０００５〜０．００３で、かつ
Ｂ量を式（１）を満足するように調整した組成を有し、 Ｂ* ≧０．０００５ （１） ただし、Ｎ≧（１４／４８）Ｔｉのとき Ｂ* ＝Ｂ−（１１／１４）Ｎ＋（１１／４８）Ｔｉ Ｎ＜（１４／４８）Ｔｉのとき Ｂ* ＝Ｂ 残部が実質的にＦｅおよび不可避的不純物からなる鋼の
スラブを熱間圧延するにあたり、前記鋼のＡｒ3 変態点
の温度をＴＡｒ3 としたとき、仕上温度Ｔｆが（ＴＡｒ
3 ＋３０）〜（ＴＡｒ3 ＋１００）℃の温度範囲になる
ように仕上げ温度Ｔｆを制御して熱間圧延し、かつその
とき３０％以上の圧下率をＴｆ〜（Ｔｆ＋３０）℃の温
度範囲で与えて熱間圧延し、熱間圧延後直ちに６０〜２
００℃／ｓの冷却速度で１５０〜２５０℃の温度範囲に
ある温度Ｔｃまで冷却後、１５０℃以上前記Ｔｃ以下の
温度範囲に２秒以上滞留させ、１５０℃未満の温度で巻
取って熱延鋼板を作製し、前記熱延鋼板を用いて式
（２）を満たす幅絞り率Ｑで造管することを特徴とする
耐水素遅れ割れ特性に優れた高張力電縫鋼管の製造方法
に関するものである。That is, in the first aspect of the present invention, in wt%, C: 0.1 to 0.19, Si: 0.01
~ 0.5, Mn: 0.8 ~ 1.6, Cr: 0.05 ~
0.6, Al: 0.01 to 0.06, P: 0.02 or less (including 0), S: 0.003 or less (including 0), N:
0.005 or less (including 0), Ti: 0.015 or less (including 0), B: 0.0005 to 0.003, and a composition in which the amount of B is adjusted to satisfy the expression (1). B * ≧ 0.0005 (1) where N ≧ (14/48) Ti B * = B− (11/14) N + (11/48) Ti N <(14/48) Ti Time B * = B In hot rolling a slab of steel whose balance substantially consists of Fe and unavoidable impurities, when the temperature of the Ar 3 transformation point of the steel is TAr 3 , the finishing temperature Tf is (TAr
3 + 30) to (TAr 3 +100) ° C., hot rolling is performed while controlling the finishing temperature Tf so that a rolling reduction of 30% or more is given in a temperature range of Tf to (Tf + 30) ° C. Hot rolling, and 60 to 2 immediately after hot rolling.
After cooling to a temperature Tc in a temperature range of 150 to 250 ° C. at a cooling rate of 00 ° C./s, the steel sheet is kept in a temperature range of 150 ° C. or more and Tc or less for 2 seconds or more, and wound at a temperature of less than 150 ° C. The present invention relates to a method for producing a high-tensile-resistance electric resistance welded steel pipe having excellent resistance to hydrogen delayed cracking, which comprises preparing a steel sheet and forming a pipe at a width reduction ratio Q satisfying the formula (2) using the hot-rolled steel sheet. is there.
【０００９】 １０００≦Ｑ／（ｔ／Ｄ）2 ≦３０００ （２） ここで、ｔ（ｍｍ）は熱延鋼板の板厚、Ｄ（ｍｍ）は電
縫鋼管の外径、Ｑ（％）は幅絞り率で、式（３）で定義
される。1000 ≦ Q / (t / D) 2 ≦ 3000 (2) where t (mm) is the thickness of the hot-rolled steel sheet, D (mm) is the outer diameter of the ERW pipe, and Q (%) is Width reduction ratio, defined by equation (3).
【００１０】 Ｑ＝〔（鋼板の幅−π（Ｄ−ｔ））／π（Ｄ−ｔ）〕×１００ （３） 鋼の成分限定理由を以下に説明する。Q = [(steel plate width−π (D−t)) / π (D−t)] × 100 (3) The reasons for limiting the components of steel will be described below.
【００１１】Ｃ：マルテンサイト生成元素であり、かつ
マルテンサイトの硬さを高める元素であるので、目標と
する強度を確保するために必須な元素である。添加量が
０．１ｗｔ％未満であると，目標とする９８０Ｎ／ｍｍ
2 以上の強度が得られない。添加量が０．１９ｗｔ％を
超えると、耐水素遅れ割れ特性が劣化する。C: Martensite-forming element and an element that increases the hardness of martensite, and thus is an essential element for securing a target strength. If the addition amount is less than 0.1 wt%, the target 980 N / mm
2 or more strength cannot be obtained. If the amount exceeds 0.19 wt%, the resistance to hydrogen delayed cracking deteriorates.
【００１２】Ｓｉ：電縫溶接部の健全性を確保するため
に添加する必要があり、添加量が０．０１〜０．５ｗｔ
％の範囲で電縫溶接部の健全性が良好となる。Si: It is necessary to add Si in order to ensure soundness of the electric resistance welded portion, and the amount of addition is 0.01 to 0.5 wt.
%, The soundness of the electric resistance welded portion is improved.
【００１３】Ｍｎ：オーステナイトの焼入れ性を上げ、
マルテンサイトを生成させ、目標とする強度を確保する
ために必須な元素である。添加量が０．８ｗｔ％未満で
あると目標とする９８０Ｎ／ｍｍ2 以上の強度が得られ
ない。添加量が１．６ｗｔ％を超えると耐水素遅れ割れ
特性が劣化する。Mn: increases the hardenability of austenite,
It is an element essential for generating martensite and securing a target strength. If the addition amount is less than 0.8 wt%, the target strength of 980 N / mm 2 or more cannot be obtained. If the addition amount exceeds 1.6 wt%, the hydrogen delayed cracking resistance deteriorates.
【００１４】Ｃｒ：Ｍｎとの相互作用により鋼の焼入れ
性を上げ、目標とする強度を確保するために必要な元素
である。添加量が０．０５ｗｔ％未満であるとその効果
が乏しい。添加量が０．６ｗｔ％を超えると耐水素遅れ
割れ特性が劣化する。Cr: An element necessary for enhancing the hardenability of steel by interaction with Mn and ensuring a target strength. If the addition amount is less than 0.05 wt%, the effect is poor. If the amount exceeds 0.6 wt%, the resistance to hydrogen delayed cracking deteriorates.
【００１５】Ａｌ：脱酸元素として添加される。また、
鋼中に固溶するＮをＡｌＮとして固定し、耐水素遅れ割
れ特性を向上させる。０．０１ｗｔ％未満だとその効果
は少ない。０．０６ｗｔ％を超えると介在物が増加し、
耐水素遅れ割れ特性が劣化する。Al: added as a deoxidizing element. Also,
N dissolved in steel is fixed as AlN to improve the resistance to hydrogen delayed cracking. If the content is less than 0.01 wt%, the effect is small. If it exceeds 0.06 wt%, inclusions increase,
Hydrogen delayed cracking resistance deteriorates.
【００１６】Ｐ：０．０２ｗｔ％を超えると耐水素遅れ
割れ特性を劣化させる。P: If it exceeds 0.02 wt%, the hydrogen delayed cracking resistance deteriorates.
【００１７】Ｓ：介在物として存在し、耐水素遅れ割れ
特性を劣化させるため、０．００３ｗｔ％以下であるこ
とが必要である。S: It is required to be 0.003 wt% or less in order to exist as inclusions and deteriorate the hydrogen delayed cracking resistance.
【００１８】Ｎ：０．００５ｗｔ％を超えると、耐水素
遅れ割れ特性が低下する。N: If it exceeds 0.005 wt%, the resistance to hydrogen delayed cracking decreases.
【００１９】Ｔｉ：固溶Ｎを固定し、Ｂの焼入れ性を確
保する効果があるので、添加する方が好ましいが、粗大
な窒化物として析出すると耐水素遅れ割れ特性を低下さ
せるので、０．０１５ｗｔ％以下である必要がある。Ti: It is preferable to add Ti because it has an effect of fixing solid solution N and securing the quenching property of B. However, precipitation as coarse nitride lowers the resistance to hydrogen delayed cracking. It must be 015 wt% or less.
【００２０】Ｂ：マルテンサイトを生成させ、目標とす
る強度を確保するために必須な元素である。添加量が
０．０００５ｗｔ％未満であると目標とする９８０Ｎ／
ｍｍ2以上の強度が得られない。また、マルテンサイト
を生成させるためには、オーステナイト中に固溶してい
るＢがフェライト変態を抑制する必要があるが、ＢはＮ
やＴｉと化合物を形成するので、オーステナイト中に固
溶ＢをＢ* としたとき、次の（１）式を満足させる必要
がある。B: An element essential for generating martensite and securing a target strength. The target 980 N / is set to be less than 0.0005 wt%.
The strength of mm 2 or more cannot be obtained. Further, in order to form martensite, it is necessary for B which is dissolved in austenite to suppress ferrite transformation.
Since Ti forms a compound with Ti and Ti, it is necessary to satisfy the following equation (1) when the solid solution B is B * in austenite.
【００２１】Ｂ* ≧０．０００５ （１） ただし、Ｎ≧（１４／４８）Ｔｉのとき Ｂ* ＝Ｂ−（１１／１４）Ｎ＋（１１／４８）Ｔｉ Ｎ＜（１４／４８）Ｔｉのとき Ｂ* ＝Ｂ なお、Ｂの添加量が０．００３ｗｔ％を超えるとその効
果が飽和する。B * ≧ 0.0005 (1) However, when N ≧ (14/48) Ti, B * = B− (11/14) N + (11/48) Ti N <(14/48) Ti When B * = B, the effect is saturated when the added amount of B exceeds 0.003 wt%.
【００２２】高張力電縫鋼管の素材である熱延鋼板の熱
延条件の限定理由を以下に説明する。The reasons for limiting the hot rolling conditions of the hot rolled steel sheet, which is the material of the high-tensile ERW steel pipe, will be described below.
【００２３】仕上温度：（ＴＡｒ3 ＋３０）℃未満だ
と、９８０Ｎ／ｍｍ2 以上の強度を得るためのマルテン
サイトの体積率が得られない。（ＴＡｒ3 ＋１００）℃
を超えると、マルテンサイトパケットが粗大化し、耐水
素遅れ割れ特性が低下する。If the finishing temperature is lower than (TAr 3 +30) ° C., the volume fraction of martensite for obtaining a strength of 980 N / mm 2 or more cannot be obtained. (TAr 3 +100) ° C.
If the ratio exceeds 2, the martensite packet becomes coarse, and the hydrogen delayed cracking resistance decreases.
【００２４】圧下率：マルテンサイトを微細にし、耐水
素遅れ割れ特性を良好にせしめるには、熱間圧延終了直
前における強圧下が必要である。それにはＴｆ〜（Ｔｆ
＋３０）℃の温度範囲で３０％以上の圧下率を与えて熱
間圧延する必要がある。Rolling reduction: In order to make the martensite fine and improve the resistance to hydrogen delayed cracking, it is necessary to perform a strong rolling immediately before the end of hot rolling. For that, Tf ~ (Tf
It is necessary to give a rolling reduction of 30% or more in a temperature range of +30) ° C. to perform hot rolling.
【００２５】熱間圧延後の冷却条件：９８０Ｎ／ｍｍ2
以上の強度を得るためのマルテンサイトの体積率を確保
するために、熱間圧延後直ちに６０〜２００℃／ｓの冷
却速度で１５０〜２５０℃の温度範囲にある温度Ｔｃま
で急冷する必要がある。冷却速度が６０℃／ｓに満たな
いと所望の体積率のマルテンサイトが得られない。冷却
速度が２００℃／ｓを超えると、操業上のトラブルを生
じる。また、２５０℃以下まで急冷しないと所望の体積
率のマルテンサイトが得られない。Cooling conditions after hot rolling: 980 N / mm 2
Immediately after hot rolling, it is necessary to rapidly cool to a temperature Tc in a temperature range of 150 to 250 ° C. at a cooling rate of 60 to 200 ° C./s in order to secure a volume ratio of martensite for obtaining the above strength. . If the cooling rate is less than 60 ° C./s, martensite having a desired volume ratio cannot be obtained. When the cooling rate exceeds 200 ° C./s, a trouble in operation occurs. Unless the temperature is rapidly cooled to 250 ° C. or lower, martensite having a desired volume ratio cannot be obtained.
【００２６】急冷後は硬質な焼戻しマルテンサイトを生
成させるため、１５０℃以上前記温度Ｔｃ以下の温度範
囲に、保持あるいは緩冷却などにより鋼板を２秒以上滞
留させる必要がある。図１に、急冷された鋼板を１５０
〜２５０℃の温度範囲で保持したときの保持時間と水素
遅れ割れ発生限界付加歪みΔεとの関係を示す。２秒以
上の保持によって、２０００μｍ以上の高い水素遅れ割
れ発生限界付加歪みΔεが安定して得られることがわか
る。２秒未満では、焼入れ歪みが残存するため、１９０
０μｍ以上の高い水素遅れ割れ発生限界付加歪みΔεが
安定して得られない。After quenching, in order to generate hard tempered martensite, it is necessary to keep the steel sheet in the temperature range of 150 ° C. or more and the temperature Tc or less by holding or slow cooling for 2 seconds or more. FIG.
The relationship between the holding time when the temperature is held in a temperature range of up to 250 ° C. and the additional strain Δε at which hydrogen delayed cracking occurs is shown. It can be seen that, by holding for 2 seconds or longer, a high limit additional strain Δε of hydrogen lag crack generation of 2000 μm or more can be stably obtained. If the time is less than 2 seconds, quenching distortion remains, so
It is not possible to stably obtain a high additional strain Δε of 0 μm or more in the occurrence limit of hydrogen delayed cracking.
【００２７】ここで、水素遅れ割れ発生限界付加歪みΔ
εとは、電縫鋼管より幅２０ｍｍのＣーリング試験片を
切出し、切出し前の外径までボルト締めを行い、電縫鋼
管の残留歪み相当の歪みを加えた後、さらに式（３）で
計算される付加歪みを加えて０．１Ｎ塩酸中に２００時
間浸漬し割れ発生有無を調べ、割れが発生する限界の付
加歪みを求め、耐水素遅れ割れ特性の指標とした。この
値が高いほど、耐水素遅れ割れの特性にとっては好まし
い。Here, the additional strain Δ at which hydrogen delayed cracking occurs
ε is a value obtained by cutting out a C-ring test piece of 20 mm width from the ERW pipe, tightening the bolt to the outer diameter before cutting, applying a strain equivalent to the residual strain of the ERW pipe, and further calculating by equation (3). After applying the additional strain, the substrate was immersed in 0.1 N hydrochloric acid for 200 hours to check for crack generation. The limit of additional strain at which cracking occurred was determined and used as an index of resistance to hydrogen delayed cracking. The higher the value, the more preferable for the property of resistance to hydrogen delayed cracking.
【００２８】 Δε＝（４・１０6 ・ｔ・δ）／（π・Ｄ・（Ｄ−ｔ）） （３） 式（３）で、ｔは板厚、Ｄは切出し前の外径、δはＤ−
（付加歪み付加後の外径） 巻取温度：１５０℃を超えると、硬質な焼戻しマルテン
サイト相とならず、９８０Ｎ／ｍｍ2 以上の強度が得ら
れない。Δε = (4 · 10 6 · t · δ) / (π · D · (Dt)) (3) In equation (3), t is the plate thickness, D is the outer diameter before cutting, and δ Is D-
(Outer diameter after application of additional strain) When the winding temperature exceeds 150 ° C., a hard tempered martensite phase is not obtained, and a strength of 980 N / mm 2 or more cannot be obtained.
【００２９】以上のような条件で製造された熱延鋼板を
用い高張力電縫鋼管を製造するにあたり、その造管条件
の限定理由を以下に説明する。When manufacturing a high-tensile-strength ERW steel pipe using the hot-rolled steel sheet manufactured under the above conditions, the reasons for limiting the pipe-forming conditions will be described below.
【００３０】図２に、前記式（２）から求めた幅絞り率
Ｑを用いて算出したＱ／（ｔ／Ｄ） 2 と水素遅れ割れ発
生限界付加歪みΔεの関係を示す。Ｑ／（ｔ／Ｄ）2 の
値が１０００以上３０００以下のとき、２０００μｍ以
上の高い水素遅れ割れ発生限界付加歪みΔεが安定して
得らる。Ｑ／（ｔ／Ｄ）2 の値が１０００未満では、残
留歪みが増大するため、また、３０００を超える場合
は、造管時に強い変形集合組織が形成されるため水素割
れ感受性が高まり、１９００μｍ以上の高い水素遅れ割
れ発生限界付加歪みΔεが得られない。FIG. 2 shows the width reduction ratio obtained from the above equation (2).
Q / (t / D) calculated using Q TwoAnd hydrogen delayed cracking
The relationship of the raw limit additional strain Δε is shown. Q / (t / D)Twoof
When the value is 1000 or more and 3000 or less, 2000 μm or less
Above high hydrogen delayed crack initiation limit Additional strain Δε is stable
I get it. Q / (t / D)TwoIs less than 1000,
When the strain increases, and when it exceeds 3000
Is a hydrogen deformation
Sensitivity increases, and a high hydrogen delay rate of 1900 μm or more
Therefore, the generation limit additional strain Δε cannot be obtained.
【００３１】請求項２に記載の第２の発明は、第１の発
明の鋼成分に加え、ｗｔ％で、Ｎｂ：０．００５〜０．
０３、Ｖ：０．００５〜０．０３のうち少なくとも１種
以上を含有するように成分調整されたスラブを用い、熱
間圧延以降の工程を第１の発明と同様な方法で行うこと
を特徴とする耐水素遅れ割れ特性に優れた高張力電縫鋼
管の製造方法に関するものである。According to a second aspect of the present invention, in addition to the steel component of the first aspect of the present invention, Nb: 0.005-0.
03, V: using a slab whose composition is adjusted to contain at least one of 0.005 to 0.03, and performing the steps after hot rolling by the same method as in the first invention. The present invention relates to a method for producing a high-tensile-resistance-welded steel pipe excellent in hydrogen delayed cracking resistance.
【００３２】Ｎｂ、Ｖ量の限定理由を以下に説明する。
Ｎｂ、Ｖは、いずれも変態前のオーステナイト粒を微細
化し、変態後のマルテンサイトパケットを微細化できる
ので、耐水素遅れ割れ特性の向上には好ましい元素であ
る。しかし０．００５ｗｔ％未満では、その効果は少な
く、また０．０３ｗｔ％を超えて過度に添加すると、耐
水素遅れ割れ特性がかえって劣化する。The reasons for limiting the amounts of Nb and V will be described below.
Both Nb and V are preferable elements for improving the hydrogen delayed cracking resistance, because they can refine the austenite grains before transformation and refine the martensite packet after transformation. However, if the content is less than 0.005 wt%, the effect is small, and if it is excessively added exceeding 0.03 wt%, the hydrogen delayed cracking resistance is rather deteriorated.
【００３３】請求項３に記載の第３の発明は、第１の発
明または第２の発明の鋼成分に加え、ｗｔ％で、Ｃｕ：
０．０５〜０．５を含有するように成分調整されたスラ
ブを用い、熱間圧延以降の工程を第１の発明と同様な方
法で行うことを特徴とする耐水素遅れ割れ特性に優れた
高張力電縫鋼管の製造方法に関するものである。According to a third aspect of the present invention, in addition to the steel component of the first or second aspect, Cu:
Using a slab whose composition is adjusted to contain 0.05 to 0.5, and performing the steps after hot rolling by the same method as in the first invention, which is excellent in hydrogen delayed cracking resistance. The present invention relates to a method for manufacturing a high tension electric resistance welded steel pipe.
【００３４】Ｃｕ量の限定理由を以下に説明する。Ｃｕ
は、鋼の腐食の進行を抑制するとともに鋼中への水素の
侵入を抑制するので、耐水素遅れ割れ特性を向上させ
る。図３に，Ｃｕ添加量と水素割れ発生限界付加歪みΔ
εの変化量との関係を示す。Ｃｕを０．０５ｗｔ％以上
添加することにより水素遅れ割れ発生限界付加歪みの変
化量は増大し、水素遅れ割れの発生が抑制される。ま
た、０．５ｗｔ％超えて添加してもその効果は飽和する
ので、その上限は０．５ｗｔ％とする。The reason for limiting the amount of Cu will be described below. Cu
In the steel, the progress of corrosion of steel and the intrusion of hydrogen into steel are suppressed, so that the hydrogen delayed cracking resistance is improved. Figure 3 shows the amount of Cu added and the additional strain Δ
The relationship with the change amount of ε is shown. By adding 0.05% by weight or more of Cu, the amount of change in the additional strain at the occurrence limit of hydrogen delayed cracking increases, and the occurrence of hydrogen delayed cracking is suppressed. The effect is saturated even if it is added in excess of 0.5 wt%, so the upper limit is set to 0.5 wt%.
【００３５】なおＣｕ量を増加すると、場合によっては
Ｃｕキズと呼ばれる表面欠陥が発生することがある。Ｎ
ｉ添加によってＣｕきずの発生を防止できるが、Ｎｉは
耐水素遅れ割れ特性にとって有害な元素であるため、そ
の添加量は０．３ｗｔ％以内に制限されることが望まし
い。When the amount of Cu is increased, a surface defect called Cu flaw may occur in some cases. N
Although the generation of Cu flaws can be prevented by the addition of i, Ni is a harmful element for the resistance to hydrogen delayed cracking, so its addition amount is preferably limited to 0.3 wt% or less.
【００３６】[0036]
（実施例１）表１に示す本発明範囲内の成分系である鋼
Ａ〜ＥとＣ量およびＢ量が本発明範囲外の鋼Ｆの６種の
鋼を溶製し、表２に示す本発明範囲内の熱延条件および
造管条件にて３４．０φ×２．３ｍｍｔの電縫鋼管を作
製した。そして、鋼管の引張強度および前記した耐水素
遅れ割れ特性の指標である水素遅れ割れ発生限界付加歪
みΔεを測定した。(Example 1) Steels A to E, which are the component systems within the scope of the present invention shown in Table 1, and six types of steels F having a C content and a B content outside the scope of the present invention were melted and shown in Table 2. An electric resistance welded steel pipe having a size of 34.0 φ × 2.3 mmt was produced under hot rolling conditions and pipe forming conditions within the scope of the present invention. Then, the tensile strength of the steel pipe and the additional strain Δε, which is a limit of the occurrence of hydrogen delayed cracking, which is an index of the hydrogen delayed cracking resistance, were measured.
【００３７】結果を表３に示す。本発明範囲内の成分系
である鋼Ａ〜Ｅは、いずれも９８０Ｎ／ｍｍ2 以上の強
度を示し、かつ２０００μｍ以上の高い水素遅れ割れ発
生限界付加歪みΔεが安定して得られる。また、組織的
には、表２に示すように１００％焼戻マルテンサイトで
あった。一方、Ｃ量およびＢ量が本発明範囲外の鋼Ｆ
は、強度上の問題はないが、水素遅れ割れ発生限界付加
歪みΔεが著しく低く、耐水素遅れ割れ特性が劣る。Table 3 shows the results. The steels A to E, which are component systems within the scope of the present invention, all exhibit a strength of 980 N / mm 2 or more, and can stably obtain a high hydrogen lagging crack generation limit additional strain Δε of 2000 μm or more. Further, as shown in Table 2, the structure was 100% tempered martensite. On the other hand, steel F whose C content and B content are out of the range of the present invention.
Although there is no problem with strength, the additional strain Δε at which hydrogen delayed cracking occurs is extremely low, and the hydrogen delayed cracking resistance is poor.
【００３８】[0038]
【表１】 [Table 1]
【００３９】[0039]
【表２】 [Table 2]
【００４０】[0040]
【表３】 [Table 3]
【００４１】（実施例２）表１の鋼Ａ〜Ｅを用い、表４
に示すような熱延条件および造管条件を種々変化させて
電縫鋼管を作製した。そして、鋼管の引張強度および水
素遅れ割れ発生限界付加歪みΔεを測定した。Example 2 Using steels A to E in Table 1, Table 4
The ERW steel pipes were produced by changing various hot rolling conditions and pipe forming conditions as shown in FIG. Then, the tensile strength of the steel pipe and the additional strain Δε at which hydrogen delayed cracking occurred were measured.
【００４２】結果を表５に示す。熱延条件、造管条件が
本発明範囲内にある電縫鋼管は、引張強度が９８０Ｎ／
ｍｍ2 で、かつ２０００μｍ以上の高い水素遅れ割れ発
生限界付加歪みΔεが安定して得られる。また、組織的
には、表４に示すように８０％以上の焼戻マルテンサイ
トとフェライトからなる複合組織であった。一方、熱延
条件、造管条件が本発明範囲外の試料では、引張強度が
不足したり、水素遅れ割れ発生限界付加歪みΔεが９５
０μｍとそれほど高くなく、かつ安定してΔεの値が得
られなかった。Table 5 shows the results. An ERW steel pipe having hot rolling conditions and pipe forming conditions within the range of the present invention has a tensile strength of 980 N /
A high value of the additional strain Δε of mm 2 and 2000 μm or more, which is a critical limit for hydrogen delayed cracking, can be stably obtained. Further, as shown in Table 4, the composite structure was composed of 80% or more of tempered martensite and ferrite. On the other hand, in the samples in which the hot rolling conditions and the tube forming conditions are out of the range of the present invention, the tensile strength is insufficient, and the additional strain Δε at which hydrogen delayed cracking can occur is 95%.
The value of Δε was not so high as 0 μm, and the value of Δε was not stably obtained.
【００４３】[0043]
【表４】 [Table 4]
【００４４】[0044]
【表５】 [Table 5]
【図１】１５０〜２５０℃の温度範囲における保持時間
と水素遅れ割れ発生限界付加歪みΔεとの関係を示す図
である。FIG. 1 is a diagram showing a relationship between a retention time in a temperature range of 150 to 250 ° C. and a limit additional strain Δε at which hydrogen delayed cracking occurs.
【図２】Ｑ／（ｔ／Ｄ）2 と水素遅れ割れ発生限界付加
歪みΔεの関係を示す図である。FIG. 2 is a diagram showing the relationship between Q / (t / D) 2 and the additional strain Δε at which hydrogen delayed cracking occurs.
【図３】Ｃｕ添加量と割れ発生限界付加歪みΔεの変化
量との関係を示す図である。FIG. 3 is a graph showing the relationship between the amount of added Cu and the amount of change in the additional strain Δε at which cracking occurs.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ Ｃ２２Ｃ 38/22 Ｃ２２Ｃ 38/22 (56)参考文献 特開 昭59−48846（ＪＰ，Ａ) 特開 平１−205032（ＪＰ，Ａ) 特開 平４−187319（ＪＰ，Ａ) 特開 平６−88129（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) B21C 37/08 C21D 38/00 - 38/60 ──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. 7 Identification symbol FI C22C 38/22 C22C 38/22 (56) References JP-A-59-48846 (JP, A) JP-A-1-205503 (JP) JP-A-4-187319 (JP, A) JP-A-6-88129 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) B21C 37/08 C21D 38/00- 38/60
Claims (3)
ｉ：０．０１〜０．５、Ｍｎ：０．８〜１．６、Ｃｒ：
０．０５〜０．６、Ａｌ：０．０１〜０．０６、Ｐ：
０．０２以下（０を含む）、Ｓ：０．００３以下（０を
含む）、Ｎ：０．００５以下（０を含む）、Ｔｉ：０．
０１５以下（０を含む）、Ｂ：０．０００５〜０．００
３で、かつＢ量を式（１）を満足するように調整した組
成を有し、 Ｂ* ≧０．０００５ （１） ただし、Ｎ≧（１４／４８）Ｔｉのとき Ｂ* ＝Ｂ−（１１／１４）Ｎ＋（１１／４８）Ｔｉ Ｎ＜（１４／４８）Ｔｉのとき Ｂ* ＝Ｂ 残部が実質的にＦｅおよび不可避的不純物からなる鋼の
スラブを熱間圧延するにあたり、前記鋼のＡｒ3 変態点
の温度をＴＡｒ3 としたとき、仕上温度Ｔｆが（ＴＡｒ
3 ＋３０）〜（ＴＡｒ3 ＋１００）℃の温度範囲になる
ように仕上温度Ｔｆを制御して熱間圧延し、かつそのと
き３０％以上の圧下率をＴｆ〜（Ｔｆ＋３０）℃の温度
範囲で与えて熱間圧延し、熱間圧延後直ちに６０〜２０
０℃／ｓの冷却速度で１５０〜２５０℃の温度範囲にあ
る温度Ｔｃまで冷却後、１５０℃以上前記Ｔｃ以下の温
度範囲に２秒以上滞留させ、１５０℃未満の温度で巻取
って熱延鋼板を作製し、前記熱延鋼板を用いて式（２）
を満たす幅絞り率Ｑで造管することを特徴とする耐水素
遅れ割れ特性に優れた高張力電縫鋼管の製造方法。 １０００≦Ｑ／（ｔ／Ｄ）2 ≦３０００ （２） ここで、ｔ（ｍｍ）は熱延鋼板の板厚、Ｄ（ｍｍ）は電
縫鋼管の外径、Ｑ（％）は幅絞り率で、式（３）で定義
される。 Ｑ＝〔（鋼板の幅−π（Ｄ−ｔ））／π（Ｄ−ｔ）〕×１００ （３）C. 0.1 to 0.19, S in wt%
i: 0.01 to 0.5, Mn: 0.8 to 1.6, Cr:
0.05-0.6, Al: 0.01-0.06, P:
0.02 or less (including 0), S: 0.003 or less (including 0), N: 0.005 or less (including 0), Ti: 0.
015 or less (including 0), B: 0.0005 to 0.00
3, and a composition in which the amount of B is adjusted to satisfy the expression (1). B * ≧ 0.0005 (1) where N ≧ (14/48) Ti B * = B− ( 11/14) N + (11/48) Ti When N <(14/48) Ti B * = B In hot rolling a slab of steel whose balance substantially consists of Fe and unavoidable impurities, Assuming that the temperature at the Ar 3 transformation point is TAr 3 , the finishing temperature Tf is (TAr 3)
3 + 30) to (TAr 3 +100) ° C., hot rolling is performed while controlling the finishing temperature Tf, and a rolling reduction of 30% or more is given in the temperature range of Tf to (Tf + 30) ° C. Hot rolling, and immediately after hot rolling,
After cooling to a temperature Tc in a temperature range of 150 to 250 ° C. at a cooling rate of 0 ° C./s, the steel sheet is kept in a temperature range of 150 ° C. or more and Tc or less for 2 seconds or more, and is rolled at a temperature of less than 150 ° C. A steel sheet is prepared, and using the hot-rolled steel sheet, the formula (2)
A method for producing a high-tensile-resistance electric resistance welded steel pipe having excellent resistance to delayed hydrogen cracking, characterized by forming a pipe at a width drawing rate Q satisfying the following. 1000 ≦ Q / (t / D) 2 ≦ 3000 (2) where t (mm) is the thickness of the hot-rolled steel sheet, D (mm) is the outer diameter of the ERW pipe, and Q (%) is the width reduction ratio. And is defined by equation (3). Q = [(width of steel sheet−π (D−t)) / π (D−t)] × 100 (3)
〜０．０３、Ｖ：０．００５〜０．０３のうち少なくと
も１種以上を含有することを特徴とする請求項１に記載
の耐水素遅れ割れ特性に優れた高張力電縫鋼管の製造方
法。2. The steel slab is in wt% and Nb: 0.005.
The method for producing a high tensile strength electric resistance welded steel pipe having excellent resistance to hydrogen delayed cracking according to claim 1, characterized in that it contains at least one or more elements of from 0.03 to 0.03, V: 0.005 to 0.03. .
０．５を含有することを特徴とする請求項１または２に
記載の耐水素遅れ割れ特性に優れた高張力電縫鋼管の製
造方法。3. The steel slab is in wt%, and Cu: 0.05 to
The method for producing a high-tensile-resistance electric resistance welded steel pipe having excellent resistance to hydrogen delayed cracking according to claim 1, wherein the steel pipe contains 0.5.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07201173A JP3111861B2 (en) | 1995-08-07 | 1995-08-07 | Manufacturing method of high-tensile-resistance electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07201173A JP3111861B2 (en) | 1995-08-07 | 1995-08-07 | Manufacturing method of high-tensile-resistance electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0947813A JPH0947813A (en) | 1997-02-18 |
| JP3111861B2 true JP3111861B2 (en) | 2000-11-27 |
Family
ID=16436577
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07201173A Expired - Fee Related JP3111861B2 (en) | 1995-08-07 | 1995-08-07 | Manufacturing method of high-tensile-resistance electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3111861B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8747578B2 (en) | 2003-12-12 | 2014-06-10 | Jfe Steel Corporation | Steel for structural part of automobile and method for producing the same |
-
1995
- 1995-08-07 JP JP07201173A patent/JP3111861B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8747578B2 (en) | 2003-12-12 | 2014-06-10 | Jfe Steel Corporation | Steel for structural part of automobile and method for producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0947813A (en) | 1997-02-18 |
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