JPH08337817A - Production of ultrahigh tensile strength electric resistance welded tube excellent in hydrogen delayed cracking resistance - Google Patents
Production of ultrahigh tensile strength electric resistance welded tube excellent in hydrogen delayed cracking resistanceInfo
- Publication number
- JPH08337817A JPH08337817A JP14320695A JP14320695A JPH08337817A JP H08337817 A JPH08337817 A JP H08337817A JP 14320695 A JP14320695 A JP 14320695A JP 14320695 A JP14320695 A JP 14320695A JP H08337817 A JPH08337817 A JP H08337817A
- Authority
- JP
- Japan
- Prior art keywords
- delayed cracking
- electric resistance
- cracking resistance
- hydrogen delayed
- outer diameter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は自動車インパクトビーム
など、構造用超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 producing a structurally high tensile strength electric resistance welded steel pipe for an automobile impact beam or the like.
【０００２】[0002]
【従来の技術】これまで、超高張力鋼管に関しては、特
開平1-205032号、特開平4-131327号、特開平4-187319
号、特開平6-57375 号、特開平6-88129 号、特開平6-17
9913号の各公報に開示されたような方法が提案されてい
る。これらの技術は、いずれも所定の化学成分を有する
鋼を引張強度９８０Ｎ／ｍｍ2 以上の高張力鋼帯とした
後、電縫溶接し高強度電縫鋼管を得る方法である。2. Description of the Related Art Up to now, Japanese Patent Laid-Open No. 1-205032, Japanese Patent Laid-Open No. 4-131327, Japanese Patent Laid-Open No. 4-187319 have been used for ultra-high-strength steel pipes.
No. 6-57375, No. 6-88129, No. 6-17
The method disclosed in each publication of 9913 is proposed. Each of these techniques is a method in which steel having a predetermined chemical composition is made into a high-strength steel strip having a tensile strength of 980 N / mm 2 or more and then electric resistance welding is performed to obtain a high strength electric resistance welded steel pipe.
【０００３】[0003]
【解決しようとする課題】上記特開平1-205032号、特開
平4-131327号、特開平4-187319号、特開平6-57375 号、
特開平6-88129 号、特開平6-179913号の各公報などに示
された方法は、造管に伴い残留歪みが存在するため、そ
の実用に際しては水素遅れ割れに対する配慮が必要であ
る。[Problems to be Solved] JP-A 1-205032, JP-A 4-131327, JP-A 4-187319, JP-A 6-57375,
In the methods disclosed in JP-A-6-88129 and JP-A-6-179913, there is residual strain associated with pipe making. Therefore, it is necessary to consider hydrogen delayed cracking in practical use.
【０００４】しかし、これまでに示された方法では、水
素遅れ割れに対する配慮がなされていないか、あるいは
なされていても十分でなく、したがって超高張力鋼管の
需要拡大が制限されている。However, in the methods presented so far, hydrogen delayed cracking is not taken into consideration, or even if it is not taken into consideration, the demand expansion of ultra-high strength steel pipe is limited.
【０００５】本発明は、水素遅れ割れという従来技術に
おける技術的課題を解決するためになされたものであ
り、引張強度９８０Ｎ／ｍｍ2 以上の耐水素遅れ割れ特
性に優れた超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 the technical problem of hydrogen delayed cracking in the prior art, and is an ultrahigh-strength electric resistance welded steel pipe having a tensile strength of 980 N / mm 2 or more and excellent in hydrogen delayed cracking resistance. It aims at providing the manufacturing method of.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、前記目的
を達成するために多くの実験的検討を行った結果、鋼成
分の調整、最適鋼帯熱処理条件及び最適造管条件の選定
（適正化）により耐水素遅れ割れ特性に優れた超高張力
電縫鋼管の製造が可能となる知見を得た。Means for Solving the Problems As a result of many experimental investigations for achieving the above-mentioned object, the inventors of the present invention have adjusted the steel composition, selected the optimum steel strip heat treatment condition and the optimum pipe forming condition ( We have obtained the knowledge that it is possible to manufacture ultra-high-strength electric resistance welded steel pipes that have excellent hydrogen-delayed cracking resistance characteristics.
【０００７】本発明はこのような知見に基づいてなされ
たものであり、第１に、重量で、Ｃ：０．１０〜０．１
８％、Ｓｉ：０．０１〜０．５％、Ｍｎ：１．０〜１．
９％、Ａｌ：０．０１〜０．０６％を含み、Ｐ：０．０
２％以下、Ｓ：０．００３％以下、Ｎ：０．００５％以
下である鋼スラブを１１５０〜１３００℃で均熱した
後、このスラブに対してＡｒ3 点以上を仕上温度とする
熱間圧延を施し、５００〜７００℃で巻取って熱延鋼帯
とし、この熱延鋼帯を酸洗冷圧後、連続焼鈍炉で８００
〜９００℃に均熱加熱後急冷し、さらに１５０〜２５０
℃で焼戻し処理を行い、得られた鋼帯を次式を満たす幅
絞り率[ Ｑ] で電縫溶接ならびにサイジングし、８０〜
１００％焼戻しマルテンサイト＋残部フェライト組織よ
りなる耐水素遅れ割れ特性に優れた引張強度９８０Ｎ／
ｍｍ2 以上の電縫鋼管を得ることを特徴とする耐水素遅
れ割れ特性に優れた超高張力電縫鋼管の製造方法を提供
する。The present invention has been made on the basis of such findings. First, by weight, C: 0.10 to 0.1.
8%, Si: 0.01 to 0.5%, Mn: 1.0 to 1.
9%, including Al: 0.01 to 0.06%, P: 0.0
2% or less, S: 0.003% or less, N: 0.005% or less steel slab is soaked at 1150 to 1300 ° C., and then hot with the Ar 3 point or more as the finishing temperature for this slab. It is rolled and wound at 500 to 700 ° C. to form a hot rolled steel strip. The hot rolled steel strip is pickled and cold pressed, and then 800 in a continuous annealing furnace.
Soak to ~ 900 ° C and then quench, then 150-250
After tempering at ℃, the obtained steel strip is electric resistance welded and sized at a width reduction ratio [Q] satisfying the following formula.
Tensile strength of 980 N / with excellent hydrogen-delayed cracking resistance consisting of 100% tempered martensite + balance ferrite structure
(EN) Provided is a method for producing an ultra-high-strength electric resistance welded steel tube excellent in hydrogen delayed cracking characteristics, which is characterized in that an electric resistance welded steel tube of mm 2 or more is obtained.
【０００８】１０００≦Ｑ／（ｔ/ Ｄ）2 ≦３０００ ただし、 Ｑ(%) ：幅絞り率（＝［｛スリットコイル幅−π( 外径
−板厚）} ／π（外径−板厚）］×100 ） ｔ(mm)：板厚 Ｄ(mm)：外径 第２に、上記第１の発明において、前記鋼スラブが、さ
らに重量％で０．００５〜０．０２％のＮｂを含むこと
を特徴とする耐水素遅れ割れ特性に優れた超高張力電縫
鋼管の製造方法を提供する。1000 ≦ Q / (t / D) 2 ≦ 3000 where Q (%): width reduction ratio (= [{slit coil width−π (outer diameter−plate thickness)} / π (outer diameter−plate thickness) )] × 100) t (mm): plate thickness D (mm): outer diameter Secondly, in the first invention, the steel slab further contains 0.005 to 0.02% by weight of Nb. Provided is a method for producing an ultra-high-strength electric resistance welded steel pipe excellent in hydrogen delayed cracking characteristics, which is characterized by including the above.
【０００９】第３に、上記第１の発明または第２の発明
において、前記鋼スラブが、さらに重量％で０．０５〜
０．５０％のＣｕを含み、Ｎｉが０．１０％以下である
ことを特徴とする耐水素遅れ割れ特性に優れた超高張力
電縫鋼管の製造方法を提供する。Thirdly, in the first invention or the second invention, the steel slab further has a weight percentage of 0.05 to.
Provided is a method for producing an ultra-high-strength electric resistance welded steel pipe having excellent hydrogen delayed cracking characteristics, which is characterized by containing 0.50% Cu and containing Ni at 0.10% or less.
【００１０】[0010]
【作用】本発明は、鋼の成分組成、熱間圧延及び連続焼
鈍炉での熱処理条件、造管条件の各製造因子を総て適正
に制御してはじめて達成されるものであり、以下、本発
明について化学成分、熱間圧延条件、連続焼鈍炉での熱
処理条件、造管条件について詳細に説明する。The present invention is achieved only by appropriately controlling all the manufacturing factors such as the composition of steel, the heat rolling conditions in the hot rolling and continuous annealing furnaces, and the pipe forming conditions. The chemical composition, hot rolling conditions, heat treatment conditions in a continuous annealing furnace, and pipe forming conditions will be described in detail.
【００１１】（１）化学成分 Ｃ： Ｃは所望の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。しかし、含
有量が０．１０％未満であると目標とする９８０Ｎ／ｍ
ｍ2 以上の強度が得られず、一方、含有量が０．１８％
を超えると、引張強度が高くなりすぎるか、あるいは焼
戻し時に析出する炭化物サイズが大きくなり、いずれに
せよ耐水素遅れ割れ特性が劣化する。したがってＣの含
有量を０．１０〜０．１８％とする。(1) Chemical component C: C is an essential element for forming a desired martensite and ensuring a target strength. However, if the content is less than 0.10%, the target is 980 N / m.
A strength of m 2 or more cannot be obtained, while the content is 0.18%
If it exceeds, the tensile strength becomes too high, or the size of carbides precipitated during tempering becomes large, and the hydrogen delayed cracking resistance deteriorates in any case. Therefore, the content of C is set to 0.10 to 0.18%.
【００１２】Ｓｉ： Ｓｉは電縫溶接部の健全性を確保
するために添加され、その効果はその含有量が０．０１
〜０．５％で発揮されるため、Ｓｉの含有量を０．０１
〜０．５％とする。Si: Si is added to secure the soundness of the electric resistance welded portion, and its effect is that the content is 0.01.
~ 0.5%, so the Si content is 0.01
~ 0.5%.
【００１３】Ｍｎ： Ｍｎは所望の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。しかし、含有量が１．０％未満であると目標とす
る９８０Ｎ／ｍｍ2 以上の強度が得られず、一方、含有
量が１．９％を超える耐水素遅れ割れ特性が劣化する。
したがって、Ｍｎの含有量を１．０〜１．９％とする。Mn: Mn is an essential element for forming a desired martensite and securing a target strength. However, if the content is less than 1.0%, the target strength of 980 N / mm 2 or more cannot be obtained, and on the other hand, the hydrogen delayed cracking resistance with the content exceeding 1.9% deteriorates.
Therefore, the Mn content is set to 1.0 to 1.9%.
【００１４】Ａｌ： Ａｌは脱酸元素として添加され、
また鋼中の不純物として存在するＮをＡｌＮとして固定
し、耐水素遅れ割れ特性に有効に作用する。しかし、そ
の添加効果は０．０１％未満では発揮されず、一方０．
０６％を超えると介在物の増大により耐水素遅れ割れ特
性が劣化する。したがってＡｌの含有量を０．０１〜
０．０６％とする。Al: Al is added as a deoxidizing element,
Further, N existing as an impurity in the steel is fixed as AlN, which effectively acts on hydrogen delayed cracking resistance. However, if the addition effect is less than 0.01%, the effect is not achieved.
If it exceeds 06%, hydrogen inclusion delayed cracking characteristics deteriorate due to the increase of inclusions. Therefore, the content of Al is 0.01 to
It is set to 0.06%.
【００１５】Ｐ： Ｐは耐遅れ破壊特性を劣化させるた
め、０．０２％以下に規制することが必要である。 Ｓ： Ｓは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、０．００３％以下に規制することが必
要である。P: Since P deteriorates the delayed fracture resistance, it is necessary to regulate P to 0.02% or less. S: S is present as inclusions and deteriorates the hydrogen delayed cracking resistance, so it is necessary to regulate S to 0.003% or less.
【００１６】Ｎ： Ｎが０．００５％を超えて含まれる
と耐水素遅れ割れ特性が低下するため、０．００５以下
に規制することが必要がある。 Ｎｂ： Ｎｂは連続焼鈍炉における加熱時のオーステナ
イト粒成長を抑制し、マルテンサイト組織を微細化し、
耐水素遅れ割れ特性を向上させる元素である。その添加
効果は０．００５％以上で認められ、一方０．０２％を
超えて添加しても添加効果が飽和する。したがって、Ｎ
ｂを添加する場合にはその含有量を０．００５〜０．０
２とする。N: If N is contained in excess of 0.005%, hydrogen delayed cracking resistance deteriorates, so it is necessary to regulate the content to 0.005 or less. Nb: Nb suppresses austenite grain growth during heating in a continuous annealing furnace, refines the martensite structure,
It is an element that improves the hydrogen delayed cracking resistance. The effect of addition is recognized at 0.005% or more, while the effect of addition is saturated even if added over 0.02%. Therefore, N
When b is added, its content is 0.005 to 0.0
Set to 2.
【００１７】Ｃｕ： Ｃｕは鋼管の腐食の進行を抑制
し、かつ鋼管中への水素の侵入を抑制し、耐水素遅れ割
れ特性を向上させる元素である。その添加効果は０．０
５％以上で認められ、一方０．５０％を超えて添加して
も添加効果が飽和する。したがって、Ｃｕを添加する場
合にはその含有量を０．０５〜０．５０％とする。Cu: Cu is an element that suppresses the progress of corrosion of the steel pipe, suppresses the intrusion of hydrogen into the steel pipe, and improves the hydrogen delayed cracking resistance. The effect of addition is 0.0
It is observed at 5% or more, while the addition effect is saturated even if it is added over 0.50%. Therefore, when Cu is added, its content is set to 0.05 to 0.50%.
【００１８】図１に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。この図から、Ｃｕ添
加によって割れ発生限界付加歪み（Δε）が増大し、水
素遅れ割れが抑制されることが理解される。FIG. 1 shows the relationship between the amount of Cu added and the amount of change in the crack addition limit additional strain (Δε). From this figure, it is understood that the addition of Cu increases the crack generation limit additional strain (Δε) and suppresses hydrogen delayed cracking.
【００１９】Ｎｉ： Ｎｉは鋳造偏析によって局所的な
腐食を助長し、耐水素遅れ割れ特性を低下させるため添
加しないことが望ましい。しかし、熱延時のＣｕ疵を回
避するためにやむなく添加する場合には、含有量を耐水
素遅れ割れ特性の低下が著しくない０．１０％以下とす
る。Ni: Ni is preferably not added because it promotes local corrosion by casting segregation and deteriorates hydrogen delayed cracking resistance. However, when it is unavoidably added in order to avoid Cu defects during hot rolling, the content is set to 0.10% or less at which the hydrogen-delayed cracking resistance does not significantly decrease.
【００２０】図２にＮｉ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。この図から、Ｎｉ添
加によって割れ発生限界付加歪み（Δε）が減少し、水
素遅れ割れが助長されることが理解される。FIG. 2 shows the relationship between the amount of Ni added and the amount of change in the crack addition limit additional strain (Δε). From this figure, it is understood that the crack addition limit additional strain (Δε) is reduced by the addition of Ni and hydrogen delayed cracking is promoted.
【００２１】（２）熱延条件 ａ．スラブ加熱温度 スラブ加熱温度はＮｂを固溶させるために１１５０℃以
上である必要がある。スラブ加熱温度が１１５０℃に満
たないと、連続焼鈍炉における加熱時にＮｂが十分なso
lute drug 効果を発揮しないため、マルテンサイト組織
が微細とはならず、Ｎｂ添加による耐水素遅れ割れ特性
の向上効果が得られない。一方、操業性の観点からスラ
ブ加熱温度の上限を１３００℃とする。(2) Hot rolling conditions a. Slab heating temperature The slab heating temperature needs to be 1150 ° C. or higher for solid solution of Nb. If the slab heating temperature is less than 1150 ° C, Nb will be sufficient when heating in a continuous annealing furnace.
Since the lute drug effect is not exerted, the martensite structure does not become fine, and the effect of improving the hydrogen delayed cracking resistance property due to the addition of Nb cannot be obtained. On the other hand, from the viewpoint of workability, the upper limit of the slab heating temperature is 1300 ° C.
【００２２】ｂ．仕上圧延温度 仕上圧延温度はＡｒ3 点以上である必要がある。仕上圧
延温度がＡｒ3 点以下であると、フェライト変態部での
Nb炭窒化物の歪誘起析出により、連続焼鈍炉における加
熱時にＮｂが十分なsolute drug 効果を発揮しないた
め、マルテンサイト組織が微細とはならず、Ｎｂ添加に
よる耐水素遅れ割れ特性の向上効果が得られない。B. Finishing rolling temperature The finishing rolling temperature must be Ar 3 points or higher. If the finish rolling temperature is below the Ar 3 point, the ferrite transformation part
Due to the strain-induced precipitation of Nb carbonitride, Nb does not exert a sufficient solute drug effect during heating in a continuous annealing furnace, so that the martensite structure does not become fine, and the effect of improving hydrogen-delayed cracking resistance due to Nb addition is improved. I can't get it.
【００２３】ｃ．巻取温度 巻取温度は５００〜７００℃とする。巻取温度が７００
℃を超えるとＮｂ炭化物が粗大化し、連続焼鈍炉におけ
る加熱時に再固溶せず、十分なsolute drug 効果を発揮
しないため、マルテンサイト組織が微細とはならず、Ｎ
ｂ添加による耐水素遅れ割れ特性の向上効果が得られな
い。一方、巻取温度が５００℃未満であると熱延鋼帯が
硬質化し、操業上問題となる。C. Winding temperature The winding temperature is 500 to 700 ° C. Winding temperature is 700
When the temperature exceeds ℃, Nb carbides become coarse, do not re-dissolve during heating in a continuous annealing furnace, and do not exert a sufficient solute drug effect, so the martensite structure does not become fine and N
The effect of improving the delayed hydrogen cracking resistance by adding b cannot be obtained. On the other hand, if the winding temperature is lower than 500 ° C, the hot-rolled steel strip becomes hard and becomes a problem in operation.
【００２４】（３）連続焼鈍炉での熱処理条件 ａ．加熱温度 連続焼鈍炉における加熱温度は８００〜９５０℃とす
る。８００℃未満では急冷後に十分な量のマルテンサイ
ト量が得られず、目標とする強度が得られない。一方、
９５０℃を越えると加熱時のオーステナイト粒粗大化に
より、微細なマルテンサイト組織が得られず、耐水素遅
れ割れ特性が低下する。(3) Heat treatment conditions in continuous annealing furnace a. Heating temperature The heating temperature in the continuous annealing furnace is 800 to 950 ° C. If it is less than 800 ° C, a sufficient amount of martensite cannot be obtained after quenching, and the target strength cannot be obtained. on the other hand,
If it exceeds 950 ° C, a fine martensitic structure cannot be obtained due to coarsening of austenite grains during heating, and hydrogen delayed cracking resistance is deteriorated.
【００２５】ｂ．焼戻し熱処理条件 加熱−急冷により得られた８０〜１００％マルテンサイ
ト＋残部フェライト組織とされた鋼帯は、１５０〜２５
０℃の温度範囲で焼戻し処理を行う。焼戻し温度１５０
℃未満ではマルテンサイト変態歪が残存し、造管後の耐
水素割れ性が低下する。一方、焼戻し温度が２５０℃を
超えると、焼戻しに伴い析出するセメンタイト相が粗大
となり、耐遅れ破壊特性が低下する。 （４）造管条件 電縫溶接−サイジングの造管工程における幅絞りは、鋼
管の耐水素遅れ割れ特性を良好にせしめるための重要な
要件であり、このためには幅絞り率Ｑを次式で示される
範囲内に制御した上で造管を行う。B. Tempering heat treatment conditions Steel strips having a 80-100% martensite + balance ferrite structure obtained by heating-quenching are 150-25
Tempering is performed in the temperature range of 0 ° C. Tempering temperature 150
If it is less than ℃, martensitic transformation strain remains, and the hydrogen cracking resistance after pipe forming decreases. On the other hand, if the tempering temperature exceeds 250 ° C., the cementite phase that precipitates with tempering becomes coarse and the delayed fracture resistance deteriorates. (4) Pipe making conditions The width reduction in the pipe making process of electric resistance welding-sizing is an important requirement for making the hydrogen delayed cracking resistance of the steel pipe good, and for this purpose, the width reduction ratio Q Pipe forming is performed after controlling the temperature within the range indicated by.
【００２６】１０００≦Ｑ／（ｔ/ Ｄ）2 ≦３０００ ただし、 Ｑ(%) ：幅絞り率（＝［｛スリットコイル幅−π( 外径
−板厚）} ／π（外径−板厚）］×100 ） ｔ(mm)：板厚 Ｄ(mm)：外径 図３にＱ／（ｔ/ Ｄ）2 と割れ発生限界付加歪みの関係
を示す。本発明者らは造管条件と耐水素遅れ割れ特性に
関する多くの実験的検討を行った結果、図３に示すよう
に、鋼管の割れ発生限界付加歪みは幅絞り率Ｑが１００
０（ｔ/ Ｄ）2〜３０００（ｔ/ Ｄ）2 の間でピークを
持ち、幅絞り率をこの範囲に制御することで優れた耐水
素遅れ割れ特性を有する鋼管が得られることを見出し
た。この適性幅絞り率は製品( 板厚/ 外径) 比により異
なり、優れた耐水素遅れ割れ特性を有する鋼管を得るた
めには( 板厚/ 外径) 比ごとに異なる幅絞り率をとる必
要がある。1000 ≦ Q / (t / D) 2 ≦ 3000 where Q (%): width reduction ratio (= [{slit coil width−π (outer diameter−plate thickness)} / π (outer diameter−plate thickness) )] × 100) t (mm): Plate thickness D (mm): Outer diameter FIG. 3 shows the relationship between Q / (t / D) 2 and the crack addition limit additional strain. As a result of many experimental studies on the pipe forming conditions and the hydrogen delayed cracking resistance, the present inventors have found that as shown in FIG.
It was found that a steel pipe having a peak between 0 (t / D) 2 and 3000 (t / D) 2 and controlling the width reduction ratio within this range can provide a steel pipe having excellent hydrogen delayed cracking resistance. . This suitable width reduction ratio depends on the product (plate thickness / outer diameter) ratio, and in order to obtain a steel pipe with excellent hydrogen delayed cracking resistance, it is necessary to take a different width reduction ratio for each (plate thickness / outer diameter) ratio. There is.
【００２７】鋼管の耐水素遅れ割れ特性が、幅絞り率Ｑ
＝１０００（ｔ/ Ｄ）2 〜３０００（ｔ/ Ｄ）2 の間で
ピークを持つ理由は次のように考えられる。すなわち、
幅絞り率が１０００（ｔ/ Ｄ）2 に満たない場合には、
鋼管の最大残留歪みが増大し、鋼管の耐水素遅れ割れ特
性が劣化する。逆に、幅絞り率が3000( ｔ/ Ｄ)2を越え
る場合には、造管にともない造管圧延集合組織が形成さ
れ、鋼管の耐水素遅れ割れ感受性が高まり鋼管の耐水素
遅れ割れ特性が劣化する。The resistance to delayed hydrogen cracking of a steel pipe depends on the width reduction ratio Q.
The reason why it has a peak between 1000 (t / D) 2 and 3000 (t / D) 2 is considered as follows. That is,
If the width reduction ratio is less than 1000 (t / D) 2 ,
The maximum residual strain of the steel pipe increases, and the hydrogen resistance delayed cracking property of the steel pipe deteriorates. On the other hand, when the width reduction ratio exceeds 3000 (t / D) 2, a pipe-forming rolling texture is formed along with the pipe making, the susceptibility to hydrogen delayed cracking of the steel pipe increases, and the hydrogen delayed cracking resistance of the steel pipe increases. to degrade.
【００２８】以上のような方法によって８０〜１００％
焼戻しマルテンサイト＋残部フェライト組織を形成する
ことにより、耐水素遅れ割れ特性に優れた引張強度９８
０Ｎ／ｍｍ2 以上の電縫鋼管が製造される。80% to 100% by the above method
By forming tempered martensite + balance ferrite structure, the tensile strength is 98 which is excellent in hydrogen delayed cracking resistance.
ERW steel pipe of 0 N / mm 2 or more is manufactured.
【００２９】[0029]
【実施例】以下、本発明の実施例について説明する。 （実施例１）表１に示す６種の鋼を溶製し、表２に示す
ように本発明で規定した熱延条件、連続焼鈍炉における
熱処理条件、造管条件にて３１．８ｍｍφ×１．６ｍｍ
ｔの電縫鋼管に造管した。Embodiments of the present invention will be described below. (Example 1) Six types of steel shown in Table 1 were melted, and as shown in Table 2, 31.8 mmφ × 1 under hot rolling conditions, heat treatment conditions in a continuous annealing furnace, and pipe forming conditions specified in the present invention. 0.6 mm
The electric resistance welded steel pipe of t was manufactured.
【００３０】これらの鋼管の引張強度、三点曲げ最大荷
重を測定するとともに、耐水素遅れ割れ試験を実施し
た。三点曲げ試験は押し金具半径＝１５２ｍｍ、支持ス
パン＝６００ｍｍで行った。耐水素遅れ割れ試験は、鋼
管より幅２０ｍｍのＣ−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鋼管の残留歪み相当の歪
みを加えた後、さらに以下の数１で示される式で計算さ
れる付加歪み（Δε）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、割れ発生限界付加歪みを
耐水素遅れ割れ特性の指標とした。結果を表３に示す。The tensile strength and maximum load of three-point bending of these steel pipes were measured, and a hydrogen resistance delayed cracking test was carried out. The three-point bending test was conducted with a pressing metal fitting radius of 152 mm and a supporting span of 600 mm. The hydrogen resistance delayed cracking test is performed by cutting out a C-ring test piece having a width of 20 mm from a steel pipe, bolting it to the outer diameter before cutting, applying a strain corresponding to the residual strain of the steel pipe, and then further indicated by the following formula 1. The additional strain (Δε) calculated by the formula was added and the sample was immersed in 0.1N hydrochloric acid for 200 hours to check for cracks. The critical strain for crack initiation was used as an index of hydrogen delayed cracking resistance. The results are shown in Table 3.
【００３１】[0031]
【数１】 [Equation 1]
【００３２】[0032]
【表１】 [Table 1]
【００３３】[0033]
【表２】 [Table 2]
【００３４】[0034]
【表３】 [Table 3]
【００３５】表３から理解されるように、本発明で規定
する組成を満足する鋼Ａ〜Ｅは比較鋼Ｆに比べ、割れ発
生限界歪みが高く、優れた耐水素遅れ割れ特性を示すこ
とが確認された。As can be seen from Table 3, Steels A to E satisfying the composition defined in the present invention have higher crack initiation critical strains than Comparative Steel F and exhibit excellent hydrogen delayed cracking resistance. confirmed.
【００３６】（実施例２）前記した鋼Ａ〜Ｄを用いて表
４に示すような熱延条件、連続焼鈍炉における熱処理条
件、造管条件、( 板厚/ 外径) 比を種々変化させて電縫
鋼管に造管した。これらの機械特性、耐水素遅れ割れ試
験結果を表５に示す。(Example 2) Using the steels A to D described above, various hot rolling conditions, heat treatment conditions in a continuous annealing furnace, pipe forming conditions and (sheet thickness / outer diameter) ratio as shown in Table 4 were changed. Made into ERW steel pipe. Table 5 shows the mechanical properties and the results of hydrogen delayed cracking test.
【００３７】[0037]
【表４】 [Table 4]
【００３８】[0038]
【表５】 [Table 5]
【００３９】表５から理解されるように、熱延条件、連
続焼鈍炉における熱処理条件、造管条件が本発明で規定
した条件を満たしている実施例の電縫鋼管は、引張強度
が９８０Ｎ／ｍｍ2 以上でかつ割れ発生限界歪みが高
く、優れた耐水素遅れ割れ特性を有することが確認され
た。As can be seen from Table 5, the electric resistance welded steel pipes of the examples in which the hot rolling conditions, the heat treatment conditions in the continuous annealing furnace, and the pipe making conditions satisfy the conditions defined in the present invention have a tensile strength of 980 N / It was confirmed that the crack resistance was higher than that of mm 2 and the crack initiation critical strain was high, and that it had excellent hydrogen delayed cracking resistance.
【００４０】[0040]
【発明の効果】以上説明したように、本発明によれば、
自動車インパクトビームなどに用いられる引張強度９８
０Ｎ／ｍｍ2 以上の耐水素遅れ割れ特性に優れた構造用
超高張力電縫鋼管を、低コストで製造することができ
る。As described above, according to the present invention,
Tensile strength 98 used for automobile impact beams
A structural ultrahigh-strength electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance of 0 N / mm 2 or more can be manufactured at low cost.
【図１】Ｃｕ添加量と割れ発生限界付加歪み変化量との
関係を示す図。FIG. 1 is a diagram showing a relationship between a Cu addition amount and a crack generation limit additional strain change amount.
【図２】Ｎｉ添加量と割れ発生限界付加歪み変化量との
関係を示す図。FIG. 2 is a diagram showing the relationship between the amount of Ni added and the amount of change in additional strain that causes cracking.
【図３】Ｑ／（ｔ/ Ｄ）2 と割れ発生限界付加歪みとの
関係を示す図。FIG. 3 is a diagram showing a relationship between Q / (t / D) 2 and crack addition limit additional strain.
Claims (3)
Ｓｉ：０．０１〜０．５％、Ｍｎ：１．０〜１．９％、
Ａｌ：０．０１〜０．０６％を含み、Ｐ：０．０２％以
下、Ｓ：０．００３％以下、Ｎ：０．００５％以下であ
る鋼スラブを１１５０〜１３００℃で均熱した後、この
スラブに対してＡｒ3 点以上を仕上温度とする熱間圧延
を施し、５００〜７００℃で巻取って熱延鋼帯とし、こ
の熱延鋼帯を酸洗冷圧後、連続焼鈍炉で８００〜９００
℃に均熱加熱後急冷し、さらに１５０〜２５０℃で焼戻
し処理を行い、得られた鋼帯を次式を満たす幅絞り率[
Ｑ] で電縫溶接ならびにサイジングし、８０〜１００％
焼戻しマルテンサイト＋残部フェライト組織よりなる耐
水素遅れ割れ特性に優れた引張強度９８０Ｎ／ｍｍ2 以
上の電縫鋼管を得ることを特徴とする耐水素遅れ割れ特
性に優れた超高張力電縫鋼管の製造方法。 １０００≦Ｑ／（ｔ/ Ｄ）2 ≦３０００ ただし、 Ｑ(%) ：幅絞り率（＝［｛スリットコイル幅−π( 外径
−板厚）} ／π（外径−板厚）］×100 ） ｔ(mm)：板厚 Ｄ(mm)：外径1. C: 0.10 to 0.18% by weight,
Si: 0.01 to 0.5%, Mn: 1.0 to 1.9%,
After soaking a steel slab containing Al: 0.01 to 0.06%, P: 0.02% or less, S: 0.003% or less, and N: 0.005% or less at 1150 to 1300 ° C. The slab is hot-rolled at a finishing temperature of Ar 3 or higher and wound at 500 to 700 ° C. to form a hot-rolled steel strip. The hot-rolled steel strip is pickled, cold-pressed, and continuously annealed. 800 ~ 900
After soaking and heating to ℃, quenching, and tempering at 150-250 ℃, the width of the steel strip obtained [
Q] ERW welding and sizing, 80-100%
A super-high-strength electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance, characterized by obtaining an electric resistance welded steel pipe composed of tempered martensite + balance ferrite structure and excellent in hydrogen delayed cracking resistance with a tensile strength of 980 N / mm 2 or more. Production method. 1000 ≦ Q / (t / D) 2 ≦ 3000, where Q (%): width drawing ratio (= [{slit coil width−π (outer diameter−plate thickness)} / π (outer diameter−plate thickness)] × 100) t (mm): Plate thickness D (mm): Outer diameter
０５〜０．０２％のＮｂを含む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超高張力電縫鋼
管の製造方法。2. The steel slab further comprises 0.0% by weight.
The method for producing an ultra-high-strength electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance according to claim 1, wherein the Nb content is 05 to 0.02%.
５〜０．５０％のＣｕを含み、Ｎｉが０．１０％以下で
あることを特徴とする請求項１または請求項２に記載の
耐水素遅れ割れ特性に優れた超高張力電縫鋼管の製造方
法。3. The steel slab further comprises 0.0% by weight.
The ultrahigh-strength electric resistance welded steel pipe excellent in hydrogen delayed cracking resistance according to claim 1 or 2, characterized in that it contains 5 to 0.50% Cu and Ni is 0.10% or less. Production method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14320695A JP3307164B2 (en) | 1995-06-09 | 1995-06-09 | Method for producing ultra-high tensile ERW steel pipe with excellent resistance to hydrogen delayed cracking |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14320695A JP3307164B2 (en) | 1995-06-09 | 1995-06-09 | Method for producing ultra-high tensile ERW steel pipe with excellent resistance to hydrogen delayed cracking |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08337817A true JPH08337817A (en) | 1996-12-24 |
| JP3307164B2 JP3307164B2 (en) | 2002-07-24 |
Family
ID=15333355
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14320695A Expired - Fee Related JP3307164B2 (en) | 1995-06-09 | 1995-06-09 | Method for producing ultra-high tensile ERW steel pipe with excellent resistance to hydrogen delayed cracking |
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| Country | Link |
|---|---|
| JP (1) | JP3307164B2 (en) |
Cited By (5)
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|---|---|---|---|---|
| WO2001096625A1 (en) * | 2000-06-14 | 2001-12-20 | Kawasaki Steel Corporation | Steel pipe for use in reinforcement of automobile and method for production thereof |
| JP2009242858A (en) * | 2008-03-31 | 2009-10-22 | Nisshin Steel Co Ltd | High-strength steel pipe and manufacturing method therefor |
| CN103757534A (en) * | 2013-12-27 | 2014-04-30 | 首钢总公司 | Cold-rolled steel plate with good flange welding property and production method of cold-rolled steel plate |
| WO2017111524A1 (en) * | 2015-12-23 | 2017-06-29 | 주식회사 포스코 | Ultra high-strength steel sheet having excellent hole expandability and manufacturing method therefor |
| JP2020110840A (en) * | 2019-01-15 | 2020-07-27 | Ｊｆｅスチール株式会社 | Electroseamed steel pipe and method for manufacture thereof |
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1995
- 1995-06-09 JP JP14320695A patent/JP3307164B2/en not_active Expired - Fee Related
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001096625A1 (en) * | 2000-06-14 | 2001-12-20 | Kawasaki Steel Corporation | Steel pipe for use in reinforcement of automobile and method for production thereof |
| JP2001355046A (en) * | 2000-06-14 | 2001-12-25 | Kawasaki Steel Corp | Steel tube for reinforcing automobile door and its production method |
| US7018488B2 (en) | 2000-06-14 | 2006-03-28 | Jfe Steel Corporation | Steel pipe for use in reinforcement of automobile and method for production thereof |
| JP4608739B2 (en) * | 2000-06-14 | 2011-01-12 | Ｊｆｅスチール株式会社 | Manufacturing method of steel pipe for automobile door reinforcement |
| JP2009242858A (en) * | 2008-03-31 | 2009-10-22 | Nisshin Steel Co Ltd | High-strength steel pipe and manufacturing method therefor |
| CN103757534A (en) * | 2013-12-27 | 2014-04-30 | 首钢总公司 | Cold-rolled steel plate with good flange welding property and production method of cold-rolled steel plate |
| WO2017111524A1 (en) * | 2015-12-23 | 2017-06-29 | 주식회사 포스코 | Ultra high-strength steel sheet having excellent hole expandability and manufacturing method therefor |
| CN108431271A (en) * | 2015-12-23 | 2018-08-21 | Posco公司 | The excellent ultrahigh-strength steel plates of hole expandability and its manufacturing method |
| JP2020110840A (en) * | 2019-01-15 | 2020-07-27 | Ｊｆｅスチール株式会社 | Electroseamed steel pipe and method for manufacture thereof |
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