JPH07113122A - Production of electric resistance welded tube to be hot-dip galvanized - Google Patents
Production of electric resistance welded tube to be hot-dip galvanizedInfo
- Publication number
- JPH07113122A JPH07113122A JP5258207A JP25820793A JPH07113122A JP H07113122 A JPH07113122 A JP H07113122A JP 5258207 A JP5258207 A JP 5258207A JP 25820793 A JP25820793 A JP 25820793A JP H07113122 A JPH07113122 A JP H07113122A
- Authority
- JP
- Japan
- Prior art keywords
- electric resistance
- resistance welded
- tube
- steel
- steel pipe
- 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
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- Coating With Molten Metal (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、例えば鉄塔用鋼管のよ
うに溶融亜鉛めっきを施される高張力鋼鋼管のうち溶融
亜鉛中での耐めっき割れ性に優れた電縫部を有する電縫
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 high-strength steel pipe to be hot-dip galvanized, such as a steel pipe for a tower, which has an electric resistance welded portion having an electric resistance welded portion excellent in plating crack resistance in molten zinc. Manufacturing method.
【０００２】[0002]
【従来の技術】高張力鋼鋼管として、一般に錆防止のた
めに亜鉛等をめっきを施した電縫鋼管が多く用いられて
いる。この場合、通常溶融亜鉛の中に鋼管を浸漬してめ
っきを行っているが、溶接熱影響部( 以後HAZ と記述す
る) の粗粒域に亜鉛めっきの粒界割れが発生する問題が
ある。2. Description of the Related Art Generally, as a high-strength steel pipe, an electric resistance welded steel pipe plated with zinc or the like for preventing rust is often used. In this case, a steel pipe is usually immersed in hot-dip zinc for plating, but there is a problem that intergranular cracking of zinc plating occurs in the coarse grain region of the weld heat affected zone (hereinafter referred to as HAZ).
【０００３】この問題の解決のため従来より技術開発が
なされている。例えば特公平２−5814号公報には、溶接
熱影響部(HAZ) の耐めっき割れ性に優れた高強度低合金
鋼の組成が開示され、これが、鉄塔用高張力鋼鋼管のJI
S 化の基となった。また、特開平２−122057号公報で
は、溶接後めっき前に、ショットブラスト処理を施し、
上記溶融亜鉛めっき割れを防止する方法が開示されてい
る。In order to solve this problem, technical development has been made conventionally. For example, Japanese Examined Patent Publication No. 2-5814 discloses the composition of a high-strength, low-alloy steel having excellent plating crack resistance in the heat-affected zone (HAZ), which is the JI of high-strength steel pipe for steel towers.
It became the basis of S conversion. Further, in Japanese Patent Laid-Open No. 122057/1990, shot blasting treatment is performed after welding and before plating.
A method for preventing the hot-dip galvanizing crack is disclosed.
【０００４】しかしながら従来技術における耐めっき割
れ性はHAZ におけるそれであって、溶接部、つまり電縫
部についてのそれではなく、最近のように高張力鋼化が
求められる状況下では電縫部における耐めっき割れ性、
特に管周方向の応力による管軸方向の割れ防止が求めら
れるようになってきている。このためには、この電縫部
の管周方向応力に対する溶融亜鉛中での伸び (塑性変形
量) の向上を図っておくことが必要である。However, the resistance to plating cracks in the prior art is that of HAZ and is not that of the welded portion, that is, the electric resistance welded portion, but the resistance to plating cracking resistance in the electric resistance welded portion under the situation where high-strength steel is demanded recently. ,
In particular, prevention of cracks in the tube axis direction due to stress in the tube circumferential direction has been demanded. For this purpose, it is necessary to improve the elongation (plastic deformation amount) in molten zinc against the stress in the circumferential direction of the electric resistance welded portion.
【０００５】ここに、電縫鋼管の場合、電縫部は管軸方
向に一直線上に存在する衝合部であり、HAZ はその周辺
の帯状部分である。従来問題としていた鋼管の耐溶融亜
鉛めっき割れ性能は一般に鋼管母材部から切り出した試
験片を管軸方向に引張って評価しているが、電縫部の割
れの評価には管周方向に引張ることも必要である。Here, in the case of an electric resistance welded steel pipe, the electric resistance welded portion is an abutting portion existing in a straight line in the pipe axial direction, and HAZ is a strip-shaped portion around the abutted portion. The hot-dip galvanizing cracking resistance of steel pipes, which has been a problem in the past, is generally evaluated by pulling a test piece cut out from the base material of the steel pipe in the pipe axial direction. Is also necessary.
【０００６】[0006]
【発明が解決しようとする課題】本発明の目的は、溶融
亜鉛めっき割れ発生を防止した、特に管周方向の応力で
の電縫鋼管の電縫部の溶融亜鉛中での割れ発生を防止し
た電縫鋼管の製造方法を提供することである。即ち、よ
り具体的には電縫部を管周方向に引張った際の伸び特性
に優れた電縫鋼管の製造方法を提供することである。SUMMARY OF THE INVENTION An object of the present invention is to prevent the occurrence of hot dip galvanizing cracks, in particular, to prevent the occurrence of cracks in the hot-dip zinc of the electric resistance welded portion of an electric resistance welded steel pipe due to stress in the pipe circumferential direction. A method for manufacturing a sewn steel pipe is provided. That is, more specifically, it is to provide a method for producing an electric resistance welded steel pipe having excellent elongation characteristics when the electric resistance welded portion is pulled in the pipe circumferential direction.
【０００７】[0007]
【課題を解決するための手段】本発明者らは、慣用の手
段で電縫鋼管を製造後、電縫部の管外面側のみの硬さ分
布を母材部硬さ±10Hvに均一化させることで、上記課題
を解決できることを見出し、本発明を完成した。Means for Solving the Problems The inventors of the present invention, after manufacturing an electric resistance welded steel pipe by a conventional means, uniformize the hardness distribution only on the outer surface side of the electric resistance welded part to a base material hardness of ± 10 Hv. Then, they have found that the above problems can be solved, and completed the present invention.
【０００８】本発明は、重量％で、Ｃ: 0.04〜0.20％、
Si: 0.05〜0.50％、Mn: 0.60〜1.80％、Ｐ: 0.025 ％以
下、Ｓ: 0.025 ％以下、Al: 0.05％以下を含み、残部Fe
および不可避的不純物より成る鋼を用いて電縫鋼管を製
造し、これに引続いて鋼管の電縫部を1050℃以下 Ac3点
＋50℃以下に加熱し、次いで Ac3点以上からの冷却に際
して、800 ℃〜500 ℃の温度領域を５〜15℃/secの速度
で冷却することを特徴とする溶融亜鉛めっきを施される
電縫鋼管の製造方法である。The present invention, in% by weight, is C: 0.04 to 0.20%,
Si: 0.05 to 0.50%, Mn: 0.60 to 1.80%, P: 0.025% or less, S: 0.025% or less, Al: 0.05% or less, balance Fe
And an electric resistance welded steel pipe is manufactured using steel consisting of unavoidable impurities, and subsequently, the electric resistance welded part of the steel pipe is heated to 1050 ° C or lower and Ac 3 point + 50 ° C or lower, and then cooled from Ac 3 or higher point. A method for producing an electric resistance welded steel pipe subjected to hot dip galvanizing, which comprises cooling a temperature range of 800 ° C to 500 ° C at a rate of 5 to 15 ° C / sec.
【０００９】本発明の好適態様によれば前記鋼組成は、
さらに、Nb: 0.01〜0.05％、Ｖ: 0.02〜0.09％、および
Ti: 0.005 〜0.050 ％、のうちの１種以上の元素を含有
していてもよい。上記処理により、電縫部の鋼管外面側
は微細アシキュラーフェライト組織で、鋼管内面側が細
粒フェライト組織である二相組織となる。According to a preferred embodiment of the present invention, the steel composition is
Furthermore, Nb: 0.01-0.05%, V: 0.02-0.09%, and
Ti: 0.005 to 0.050%, and may contain at least one element. By the above treatment, a two-phase structure is formed in which the outer surface side of the steel pipe of the electric resistance portion has a fine acicular ferrite structure and the inner surface side of the steel pipe has a fine grain ferrite structure.
【００１０】[0010]
【作用】本発明に用いる高張力鋼の鋼組成を上述のよう
に限定した理由を説明する。なお、本明細書において
「％」は特にことわりがない限り「重量％」である。The reason why the steel composition of the high-strength steel used in the present invention is limited as described above will be explained. In this specification, "%" is "% by weight" unless otherwise specified.
【００１１】Ｃ:Ｃは強度を高めるために必須の元素
で、必要とされる引張強度を確保するためには0.04％以
上必要である。しかし、余り多すぎるとHAZ のめっき割
れを起こしやすいので、上限値を0.20％とした。従っ
て、Ｃ量は0.04〜0.20％とした。C: C is an essential element for increasing the strength, and 0.04% or more is necessary to secure the required tensile strength. However, if the amount is too large, HAZ plating cracks are likely to occur, so the upper limit was made 0.20%. Therefore, the amount of C is set to 0.04 to 0.20%.
【００１２】Si:Siは脱酸元素として、さらには強度確
保のため必須であり、最低0.05％は必要であるが、HAZ
めっき割れ性の点からは低い程よく、上限を0.50％とし
た。従ってSi量は0.05〜0.50％とした。Si: Si is essential as a deoxidizing element and for securing strength, and at least 0.05% is necessary.
The lower the better from the viewpoint of plating cracking resistance, the upper limit was made 0.50%. Therefore, the Si content is set to 0.05 to 0.50%.
【００１３】Mn:MnはＣと同様、鋼材の強度確保上有効
な元素であり、0.60％以上必要である。また1.80％を超
えるとHAZ のめっき割れが発生しやすくなる。従ってMn
量は0.60％〜1.80％とした。Like C, Mn: Mn is an element effective in securing the strength of the steel material and is required to be 0.60% or more. If it exceeds 1.80%, HAZ plating cracks are likely to occur. Therefore Mn
The amount was 0.60% to 1.80%.
【００１４】Ｐ:Ｐは、鋼材の靱性を悪化させ脆化させ
る元素であり、低い方が望ましく0.025％以下とした。P: P is an element that deteriorates the toughness of the steel material and causes embrittlement, and it is desirable that the P content be as low as 0.025% or less.
【００１５】Ｓ:ＳはMnS の介在物を生成し靱性劣化を
引起こす元素であり、低い方が望ましく0.025 ％以下と
した。S: S is an element that causes inclusion of MnS and causes deterioration of toughness, and its lower content is desirable and 0.025% or less.
【００１６】Al:Alは脱酸元素として使用するが、0.050
％を超えて含有させても脱酸の効果はほとんど不変
で、HAZ のめっき割れが発生しやすくなるので、上限を
0.050 ％とした。Al: Al is used as a deoxidizing element, but 0.050
%, The effect of deoxidation remains almost unchanged and HAZ plating cracks are likely to occur.
It was set to 0.050%.
【００１７】Nb:Nbは0.01％以上含有させると強度を高
める効果がある。しかし、0.05％超えて含有するとHAZ
のめっき割れが起こる。従ってNb量は0.01％〜0.05％と
した。Nb: Nb has the effect of increasing the strength if contained in an amount of 0.01% or more. However, if the content exceeds 0.05%, HAZ
Plating cracks occur. Therefore, the amount of Nb is set to 0.01% to 0.05%.
【００１８】Ｖ:Ｖは0.02％以上含有するとTiと同時添
加したときにHAZ の耐めっき割れ性が向上する。しかし
0.09％を超えてＶを含有させると、耐めっき割れ性は著
しく劣化してくる。従ってＶ量は0.02％〜0.09％とし
た。V: When V is contained in an amount of 0.02% or more, the plating crack resistance of HAZ is improved when it is added together with Ti. However
If V is contained in excess of 0.09%, the plating crack resistance is significantly deteriorated. Therefore, the V amount is set to 0.02% to 0.09%.
【００１９】Ti:TiはＶとの複合添加により、HAZ の耐
めっき割れ性を向上させる。しかし、Ti量が0.050 ％を
超えると、もはや複合効果はなくなり、耐めっきわれ性
は著しく劣化する。従ってTi量は0.005 ％〜0.050 ％と
した。Ti: Ti improves the plating crack resistance of HAZ when added together with V. However, when the Ti content exceeds 0.050%, the composite effect is no longer present and the plating resistance is significantly deteriorated. Therefore, the Ti content is set to 0.005% to 0.050%.
【００２０】次に、鋼管の熱処理の限定理由を列挙す
る。鋼管の電縫部を1050℃以下 Ac3点＋50℃以上に加熱
することは、電縫溶接により急速加熱・冷却された組織
を再度オーステナイト化するためである。Ac3 点以上か
らの冷却に際して800 ℃から500 ℃の間の温度領域まで
を５〜15℃/secの速度で冷却することは、この温度域を
この冷却速度で冷却することにより鋼管外面側は微細ア
シキュラーフェライト組織となり、管内面側は微粒フェ
ライト組織となるためである。Next, the reasons for limiting the heat treatment of the steel pipe will be listed. Heating the electric resistance welded portion of the steel pipe to 1050 ° C or lower and Ac 3 point + 50 ° C or higher is to re-austenize the structure rapidly heated and cooled by electric resistance welding. When cooling from the Ac 3 point or higher, it is necessary to cool the temperature range between 800 ℃ and 500 ℃ at a rate of 5 to 15 ℃ / sec. By cooling this temperature range at this cooling rate, This is because it has a fine acicular ferrite structure and the inner surface of the tube has a fine grain ferrite structure.
【００２１】また、鋼管の全体でなく、電縫部を加熱す
るのは、電縫溶接により組織悪化した部分 (すなわち電
縫部) の組織改善を目的としているためである。かくし
て、本発明によれば電縫部における鋼管外面側は微細ア
シキュラーフェライト組織となり、管内面側は細粒フェ
ライト組織となり、管外面における電縫部の硬さ分布を
母材の硬さの±10Hv以内とすることができ、管周方向の
応力による管軸方向の耐めっき割れ性は著しく改善され
る。The reason why the electric resistance welded portion is heated instead of the entire steel pipe is to improve the microstructure of the portion where the microstructure deteriorates due to electric resistance welding (that is, the electric resistance welded portion). Thus, according to the present invention, the outer surface side of the steel pipe in the electric resistance portion has a fine acicular ferrite structure, the inner surface side of the pipe has a fine grain ferrite structure, and the hardness distribution of the electric resistance portion in the outer surface of the pipe is within ± 10 Hv of the hardness of the base material. Therefore, the resistance to plating cracks in the pipe axial direction due to the stress in the pipe circumferential direction is significantly improved.
【００２２】ここで本発明により耐めっき割れ性が改善
される機構についてはまだ十分解明されていないが、一
応次のように考えることができる。電縫部近傍の硬さが
周辺に比べ低下していると、溶融亜鉛めっき時の熱応力
のうち管周方向応力によって硬さ変化部にひずみの集中
が起こり、溶融亜鉛中での伸び性能の劣る場合には割れ
に結びつく。従って、少なくとも溶融亜鉛が施される管
外面部の硬さを、電縫部と母材部とで同等にしておけ
ば、ひずみ集中は生じず、めっき割れ性が改善される。Although the mechanism by which the present invention improves the plating crack resistance is not yet fully understood, it can be considered as follows. If the hardness in the vicinity of the electric resistance part is lower than that in the vicinity, strain concentrates in the hardness change part due to the stress in the pipe circumferential direction of the thermal stress during hot dip galvanizing, and the elongation performance in hot dip zinc is poor. In some cases it leads to cracking. Therefore, if the hardness of the outer surface of the pipe to which at least molten zinc is applied is made equal in the electric resistance portion and the base material portion, strain concentration does not occur and the plating cracking property is improved.
【００２３】[0023]
（試験方法）下記の電縫部の溶融亜鉛中での伸び (塑性
変形量) 評価法を用い、各種要因の解析を行った。図１
に引張試験片を示した。図１(a) はその平面図、図１
(b) は断面図である。これは、中央に電縫部がくるよう
に鋼管から切り出した試験片であり、管周方向に引張っ
て伸び (塑性変形量) 性能を評価した。(Test method) Various factors were analyzed using the following method for evaluating the elongation (plastic deformation amount) of molten seam in molten zinc. Figure 1
The tensile test piece is shown in FIG. 1 (a) is a plan view of FIG.
(b) is a sectional view. This is a test piece cut out from a steel pipe so that the electric resistance welded portion is located in the center, and the elongation (plastic deformation amount) performance was evaluated by pulling in the circumferential direction of the pipe.
【００２４】溶融亜鉛中での引張試験は次の要領で行っ
た。 (1) 引張試験装置に試験片をセットした。 (2) 試験片を 450〜460 ℃の溶融亜鉛中に２分間浸漬
し、そのまま引張試験を開始した。その引張速度は１〜
２mm／分として、破断まで行った。なお、本試験は管外
面からの割れ発生を問題としているため、管内面側に相
当する試験片表面は不めっき処理を行った。The tensile test in molten zinc was carried out as follows. (1) The test piece was set in the tensile tester. (2) The test piece was immersed in molten zinc at 450 to 460 ° C for 2 minutes, and the tensile test was started as it was. The pulling speed is 1
It was set to 2 mm / min and was broken. Since the problem of this test is the occurrence of cracks from the outer surface of the pipe, the surface of the test piece corresponding to the inner surface of the pipe was unplated.
【００２５】(3) 上記試験において図２に示すような荷
重−伸び線図を描き、最高荷重時までの伸び (塑性変形
量あるいは一様伸び) Ｌを求め、試験片平行部距離で除
して(ELZ＝L)／50×100(%)とした。ELZ は亜鉛(Zn)浴中
での伸びを示し、記号Ｚは亜鉛を意味する。ここで、EL
Z ≧2.5 ％のとき亜鉛浴中での引張試験において電縫部
での破断がなくなる。(3) In the above test, draw a load-elongation diagram as shown in FIG. 2, find the elongation (plastic deformation amount or uniform elongation) L up to the maximum load, and divide by the parallel part distance of the test piece. (ELZ = L) / 50 × 100 (%). ELZ represents elongation in a zinc (Zn) bath, and the symbol Z means zinc. Where EL
When Z ≥ 2.5%, rupture at the electric resistance welds disappears in the tensile test in the zinc bath.
【００２６】図２にＬの求め方を示した。破断点から弾
性伸び部分と平行線をひき、横軸との交点をＬとした。FIG. 2 shows how to obtain L. A parallel line was drawn from the breaking point to the elastic extension, and the intersection with the horizontal axis was designated as L.
【００２７】（実施例）熱間圧延法によって表１に示す
化学成分の帯鋼を製造した。(Example) A steel strip having the chemical composition shown in Table 1 was manufactured by the hot rolling method.
【００２８】[0028]
【表１】 [Table 1]
【００２９】次いでこれらの鋼帯を造管ラインで連続的
に成形し、引き続き慣用条件下で電気抵抗溶接を施した
後切断して、外径508 mm、肉厚12mmの電縫鋼管を製造し
た。Next, these steel strips were continuously formed in a pipe making line, and subsequently subjected to electric resistance welding under common conditions and then cut to produce an electric resistance welded steel pipe having an outer diameter of 508 mm and a wall thickness of 12 mm. .
【００３０】図３は、本発明の造管ラインの溶接部と熱
処理部を示す概略構成図で、図中、連続成形された帯鋼
１の縁部が電極２によって通電加熱されるとともに、ス
クイズロール３によって押圧されて接合され、電縫鋼管
４が形成される。これに引続いて、電縫鋼管４の溶接部
は誘導加熱装置５によって加熱昇温された後、水冷装置
６からのシャワー７によってミスト水冷される。FIG. 3 is a schematic diagram showing the welded portion and heat treated portion of the pipe making line of the present invention. In the figure, the edge portion of the continuously formed strip steel 1 is electrically heated by the electrode 2 and the squeeze is performed. The roller 3 is pressed and joined to form the electric resistance welded steel pipe 4. Following this, the welded portion of the electric resistance welded steel pipe 4 is heated and heated by the induction heating device 5 and then mist water cooled by the shower 7 from the water cooling device 6.
【００３１】図４にこのときの水冷条件と、電縫部の溶
融亜鉛中伸び、ELZ の関係を示した。ここで言う冷却速
度とは電縫部の管外面から１mmの位置のものである。図
４から分かるように本発明の鋼種Ａは、冷却速度５〜15
℃/secで目標伸び（ELZ)の2.5 ％以上となっているが、
比較の鋼種Ｂは、最高でもELZ が2.0 ％以下と目標を達
していなかった。FIG. 4 shows the relationship between the water-cooling condition at this time, the elongation in molten zinc of the electric resistance portion, and ELZ. The cooling rate referred to here is a position 1 mm from the outer surface of the electric-welded portion. As can be seen from FIG. 4, the steel type A of the present invention has a cooling rate of 5 to 15
It is 2.5% or more of the target elongation (ELZ) at ℃ / sec,
The comparative steel type B had a maximum ELZ of 2.0% or less, which was not the target.
【００３２】次に本発明の鋼種Ａを用いて、ミスト水冷
をした場合（本発明例、冷却速度10℃/sec）とミスト水
冷をしない時（比較例、冷却速度１〜２℃/sec）の電縫
部近傍の硬さ分布の測定を行った。Next, using the steel type A of the present invention, with mist water cooling (invention example, cooling rate 10 ° C./sec) and without mist water cooling (comparative example, cooling rate 1-2 ° C./sec) The hardness distribution in the vicinity of the electric resistance welded portion was measured.
【００３３】図５(a) は、硬さ測定位置を示す断面図で
あって、図５(b) は、ミスト水冷した場合の電縫部近傍
の硬さ分布、図５(c) は、ミスト水冷しなかった場合
の、電縫部近傍の硬さ分布を示すグラフである。図中、
「○」は管外面側から１mmの位置の硬さ分布を、「●」
は管内面側から１mmの位置の硬さ分布を表わす。FIG. 5 (a) is a cross-sectional view showing the hardness measurement position. FIG. 5 (b) is the hardness distribution near the electric seam portion when the mist is water-cooled, and FIG. 5 (c) is the mist. It is a graph which shows the hardness distribution in the vicinity of the electric resistance welded portion without water cooling. In the figure,
"○" indicates the hardness distribution at the position of 1 mm from the outer surface of the pipe, "●"
Represents the hardness distribution at a position 1 mm from the inner surface of the pipe.
【００３４】図５(a) 〜(c) に示したように、本発明の
電縫鋼管製造法によって電縫部の管外面側のみの組織を
微細アシキュラーフェライト組織とし、電縫部の硬さ分
布を母材部硬さ±10Hvに均一化させることができた。さ
らに、電縫部の溶融亜鉛中伸びELZ を図４に示した如く
向上させることができた。比較例の場合、母材との硬さ
の差は管内外面ともにほぼHv 40 以上とみられる。As shown in FIGS. 5 (a) to 5 (c), according to the method for producing an electric resistance welded steel pipe of the present invention, the microstructure of only the outer surface of the electric resistance welded portion is a fine acicular ferrite structure, and the hardness distribution of the electric resistance welded portion is obtained. Was made uniform to a base material hardness of ± 10 Hv. Furthermore, the ELZ in the molten zinc in the electric resistance welded portion could be improved as shown in FIG. In the case of the comparative example, the difference in hardness from the base material is considered to be approximately Hv 40 or more on both the inner and outer surfaces of the pipe.
【００３５】[0035]
【発明の効果】本発明の方法によって、電縫部の鋼管外
面側は微細アシキュラーフェライト組織で、鋼管内面側
は細粒フェライト組織なる二相組織となったため、電縫
部の管外面側のみの硬さが母材部硬さ±10Hvに均一化し
たうえで、電縫部の溶融亜鉛中での伸び (塑性変形量)
が向上し、ELZ が2.5 ％以上となった。According to the method of the present invention, the outer surface side of the electric-welded portion has a fine acicular ferrite structure and the inner surface side of the steel pipe has a fine-grained ferrite structure. Of the base metal to a hardness of ± 10 Hv, and the elongation of the electric resistance welded portion in molten zinc (amount of plastic deformation)
Was improved and ELZ was over 2.5%.
【図１】図1(a)は溶融亜鉛中での引張試験に用いる試験
片の平面図、図1(b)は溶融亜鉛中での引張試験に用いる
試験片の断面図である。FIG. 1 (a) is a plan view of a test piece used for a tensile test in molten zinc, and FIG. 1 (b) is a cross-sectional view of a test piece used for a tensile test in molten zinc.
【図２】荷重−伸び線図とELZ を求めるためのＬの求め
方を示すグラフである。FIG. 2 is a load-elongation diagram and a graph showing how to obtain L for obtaining ELZ.
【図３】本発明の鋼管製造ラインの溶接部と熱処理部を
示す概略構成図である。FIG. 3 is a schematic configuration diagram showing a welded portion and a heat treated portion of the steel pipe production line of the present invention.
【図４】冷却条件と電縫部の溶融亜鉛中の伸び（ELZ ）
の関係を示すグラフである。[Fig. 4] Cooling condition and elongation of molten seam in ERW (ELZ)
It is a graph which shows the relationship of.
【図５】図５(a) は、硬さ測定位置を示す断面図、図５
(b) は、ミスト水冷した場合の、電縫部近傍の硬さ分布
を示すグラフ、そして図５(c) は、ミスト水冷しなかっ
た場合の、電縫部近傍の硬さ分布を示すグラフである。5 (a) is a cross-sectional view showing a hardness measurement position, FIG.
(b) is a graph showing the hardness distribution in the vicinity of the electric resistance part when water is cooled with the mist, and FIG. 5 (c) is a graph showing the hardness distribution in the vicinity of the electric resistance part when the mist is not water cooled. .
１：成形帯鋼 ２：チップ電極 ３：スクイーズロール ４：電縫鋼管 ５：誘導加熱装置 ６：水冷装置 ７：水シャワー 1: Formed steel strip 2: Chip electrode 3: Squeeze roll 4: ERW steel pipe 5: Induction heating device 6: Water cooling device 7: Water shower
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２３Ｃ 2/28 2/38 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location C23C 2/28 2/38
Claims (2)
％、 Ｐ: 0.025 ％以下、Ｓ: 0.025 ％以下、Al: 0.05％以下
を含み、 残部Feおよび不可避的不純物より成る鋼組成を有する鋼
を用いて電縫鋼管を製造し、これに引続いて該電縫鋼管
の電縫部を1050℃以下 Ac3点＋50℃以上に加熱し、次い
でAc3 点以上からの冷却に際して、800 〜500 ℃の温度
領域を５〜15℃/secの速度で冷却することを特徴とする
溶融亜鉛中での伸び特性に優れた電縫部を有する溶融亜
鉛めっきを施される電縫鋼管の製造方法。1. In weight%, C: 0.04 to 0.20%, Si: 0.05 to 0.50%, Mn: 0.60 to 1.80
%, P: 0.025% or less, S: 0.025% or less, Al: 0.05% or less, and an electric resistance welded steel pipe is manufactured using a steel having a steel composition of balance Fe and unavoidable impurities. The electric resistance welded portion of the electric resistance welded steel pipe is heated to 1050 ° C or lower to Ac 3 point + 50 ° C or higher, and then when cooled from Ac 3 point or higher, the temperature range of 800 to 500 ° C is cooled at a rate of 5 to 15 ° C / sec. A method for producing an electric resistance welded steel pipe that is subjected to hot dip galvanizing and has an electric resistance welded portion having excellent elongation characteristics in molten zinc.
％、Ｖ: 0.02〜0.09％、およびTi: 0.005 〜0.050 ％の
うちの１種以上の元素を含有する請求項１記載の電縫鋼
管の製造方法。2. The steel composition further comprises Nb: 0.01-0.05.
%, V: 0.02 to 0.09%, and Ti: 0.005 to 0.050%, at least one element being contained. The method for producing an electric resistance welded steel pipe according to claim 1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5258207A JP2827842B2 (en) | 1993-10-15 | 1993-10-15 | Manufacturing method of galvanized ERW steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5258207A JP2827842B2 (en) | 1993-10-15 | 1993-10-15 | Manufacturing method of galvanized ERW steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH07113122A true JPH07113122A (en) | 1995-05-02 |
| JP2827842B2 JP2827842B2 (en) | 1998-11-25 |
Family
ID=17317006
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5258207A Expired - Fee Related JP2827842B2 (en) | 1993-10-15 | 1993-10-15 | Manufacturing method of galvanized ERW steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2827842B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002363720A (en) * | 2001-06-08 | 2002-12-18 | Nippon Steel Corp | HOT DIP Zn-Al-Mg-Si ALLOY PLATED STEEL TUBE HAVING EXCELLENT CORROSION RESISTANCE |
| CN103302134A (en) * | 2013-05-31 | 2013-09-18 | 湖南省金为型材有限公司 | Process for manufacturing zinc steel pipe section |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5367638A (en) * | 1976-11-30 | 1978-06-16 | Nippon Kokan Kk | Method of preventing zinc plating seizure of electroounite portion of electroounite tube |
| JPS578848A (en) * | 1980-06-19 | 1982-01-18 | Seiko Epson Corp | Microprogram control circuit |
| JPS57104656A (en) * | 1980-12-22 | 1982-06-29 | Nippon Kokan Kk <Nkk> | Manufacture of high-tensile steel with low galvanizing crack sensitivity |
| JPH025814A (en) * | 1988-06-27 | 1990-01-10 | Kanto Mahiki Unyu Kk | Apparatus for inducing animal to carrier |
| JPH0361352A (en) * | 1989-07-28 | 1991-03-18 | Nippon Steel Corp | Manufacture of hot dip-galvanized hot rolled steel sheet |
-
1993
- 1993-10-15 JP JP5258207A patent/JP2827842B2/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5367638A (en) * | 1976-11-30 | 1978-06-16 | Nippon Kokan Kk | Method of preventing zinc plating seizure of electroounite portion of electroounite tube |
| JPS578848A (en) * | 1980-06-19 | 1982-01-18 | Seiko Epson Corp | Microprogram control circuit |
| JPS57104656A (en) * | 1980-12-22 | 1982-06-29 | Nippon Kokan Kk <Nkk> | Manufacture of high-tensile steel with low galvanizing crack sensitivity |
| JPH025814A (en) * | 1988-06-27 | 1990-01-10 | Kanto Mahiki Unyu Kk | Apparatus for inducing animal to carrier |
| JPH0361352A (en) * | 1989-07-28 | 1991-03-18 | Nippon Steel Corp | Manufacture of hot dip-galvanized hot rolled steel sheet |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002363720A (en) * | 2001-06-08 | 2002-12-18 | Nippon Steel Corp | HOT DIP Zn-Al-Mg-Si ALLOY PLATED STEEL TUBE HAVING EXCELLENT CORROSION RESISTANCE |
| JP4634652B2 (en) * | 2001-06-08 | 2011-02-16 | 新日本製鐵株式会社 | Hot-dip Zn-Al-Mg-Si alloy-plated steel pipe with excellent corrosion resistance |
| CN103302134A (en) * | 2013-05-31 | 2013-09-18 | 湖南省金为型材有限公司 | Process for manufacturing zinc steel pipe section |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2827842B2 (en) | 1998-11-25 |
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