JPH05320775A - Production of electric resistance welded steel tube excellent in low temperature toughness - Google Patents
Production of electric resistance welded steel tube excellent in low temperature toughnessInfo
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- JPH05320775A JPH05320775A JP13065892A JP13065892A JPH05320775A JP H05320775 A JPH05320775 A JP H05320775A JP 13065892 A JP13065892 A JP 13065892A JP 13065892 A JP13065892 A JP 13065892A JP H05320775 A JPH05320775 A JP H05320775A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、溶接部の靭性が優れた
電縫鋼管の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an electric resistance welded steel pipe having excellent toughness at a welded portion.
【０００２】[0002]
【従来の技術】電縫鋼管の溶接部の靭性を向上させるた
めに、従来一般的に行われていたノルマライジング処理
に代えて、焼入れ焼戻しをする方法が、例えば特開昭５
９−４３８２７号公報あるいは特開昭５９−１５３８３
９号公報等に開示されている。この熱処理は焼入れによ
る結晶粒の微細化を狙ったものであり、微細なフェライ
ト組織を得ることで靭性の向上を図るものである。しか
し焼入れの際外面側がより高温であること、外面冷却の
ため外面側の冷却速度が大きいことにより、外面がベー
ナイトなどの焼入れ組織となり硬度上昇を招いて靭性が
劣化する恐れがある。さらに焼入れの際の急冷によりシ
ーム加熱時の２相域に島状マルテンサイトが生成し母材
に比べて硬度がかなり上昇するという悪影響がある。2. Description of the Related Art In order to improve the toughness of a welded portion of an electric resistance welded steel pipe, a method of quenching and tempering instead of the normalizing treatment which has been generally used in the past has been disclosed, for example, in Japanese Patent Laid-Open Publication No.
9-43827 or JP-A-59-15383.
It is disclosed in Japanese Patent Publication No. 9 and the like. This heat treatment is aimed at refining the crystal grains by quenching, and aims to improve the toughness by obtaining a fine ferrite structure. However, during quenching, the outer surface side has a higher temperature, and the cooling rate of the outer surface side is high due to the cooling of the outer surface, so that the outer surface becomes a quenched structure such as bainite, which may increase hardness and deteriorate toughness. Furthermore, there is an adverse effect that island-like martensite is generated in the two-phase region during seam heating due to rapid cooling during quenching and the hardness is considerably increased compared to the base metal.
【０００３】これを改善するために特開平４−４１６１
９号公報に、電縫部の再加熱後の水冷速度、冷却停止温
度を適正に制御することにより微細フェライト組織を形
成して靭性を向上させる方法が記載されている。この技
術では、一般的に焼入れ焼戻しに比べてシーム部外面の
硬度は下がり靭性は向上する傾向にあるものの、鋼種に
よっては冷却速度が不適当で依然として溶接部外面側が
焼入れ組織となる危険性があり、またシーム加熱時の２
相域には、やはり島状マルテンサイトが生成するため、
シーム及びその近傍全体に渡って硬度は母材と同等には
ならないという欠点がある。In order to improve this, Japanese Patent Laid-Open No. 4-4161
No. 9 discloses a method of forming a fine ferrite structure to improve the toughness by appropriately controlling the water cooling rate after the reheating of the electric resistance portion and the cooling stop temperature. In this technology, the hardness of the outer surface of the seam part tends to decrease and the toughness tends to improve compared to quenching and tempering, but depending on the steel type, the cooling rate is inappropriate and there is a risk that the outer surface of the welded part will still have a hardened structure. , Again when the seam is heated
Since martensite islands are formed in the region,
There is a drawback that the hardness is not the same as that of the base metal over the entire seam and its vicinity.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、電縫管溶接
部の冷却過程に改善を加え、鋼種毎に冷却速度を調整し
冷却停止を行ってシーム部外面側の組織を確実に微細フ
ェライトにし、さらにその後焼戻しを加えることによっ
て、溶接部の靭性を向上させ、またシーム及びその近傍
全体に渡って母材とほぼ同等の硬度を有する、低温靭性
に優れた均一な材質の電縫鋼管を製造することを目的と
する。DISCLOSURE OF THE INVENTION The present invention improves the cooling process of the electric resistance welded pipe, and adjusts the cooling rate for each steel type to stop the cooling to ensure that the structure on the outer surface side of the seam portion is a fine ferrite. And then tempering it to improve the toughness of the welded part, and to obtain an ERW steel pipe of uniform material with excellent low-temperature toughness that has almost the same hardness as the base metal over the entire seam and its vicinity. Intended to be manufactured.
【０００５】[0005]
【課題を解決するための手段】本発明は上記の目的を達
成するためになされたものであって、Ｃ：０．０１〜
０．１０重量％、Ｓｉ：０．５重量％以下、Ｍｎ：０．
５〜２．０重量％、Ｐ：０．０３０重量％以下、Ｓ：
０．００８重量％以下、Ｎ：０．０１重量％以下、Ａ
ｌ：０．０６重量％以下を含み、かつＮｂ：０．１重量
％以下、Ｖ：０．１重量％以下、Ｔｉ：０．０５重量％
以下のうちの一種以上を含有し、残部Ｆｅ及び不可避的
不純物よりなる帯鋼を連続的に成形した後に電縫溶接
し、これに引き続いて溶接部をＡｃ3 変態点以上、１０
５０℃以下に加熱した後、８００℃以上の温度から（Ａ
ｒ1 変態点＋１００℃）以下（Ａｒ1 変態点−１００
℃）以上の温度範囲の所定温度まで１０℃／ｓｅｃ以上
かつ前記鋼のＣＣＴ曲線から求まるフェライトが析出す
る冷却速度で強制冷却し、引続きその温度から４００℃
以下まで空冷した後に、再び該溶接部を６００℃以上８
００℃以下に加熱して焼戻すことを特徴とする低温靭性
に優れた電縫鋼管の製造方法である。The present invention has been made to achieve the above-mentioned object, and C: 0.01-
0.10 wt%, Si: 0.5 wt% or less, Mn: 0.
5 to 2.0% by weight, P: 0.030% by weight or less, S:
0.008% by weight or less, N: 0.01% by weight or less, A
1: 0.06 wt% or less and Nb: 0.1 wt% or less, V: 0.1 wt% or less, Ti: 0.05 wt%
A steel strip containing one or more of the following, the balance of which is Fe and unavoidable impurities, is continuously formed and then electric resistance welded. Subsequently, the welded portion has an Ac 3 transformation point or more, 10 or more.
After heating to 50 ° C or below, from the temperature of 800 ° C or above (A
r 1 transformation point + 100 ° C.) or lower (Ar 1 transformation point −100)
(° C.) Or higher to a predetermined temperature of 10 ° C./sec or more and forced cooling at a cooling rate at which ferrite precipitated from the CCT curve of the steel precipitates, and then 400 ° C. from that temperature.
After air-cooling to below, the welded part is again heated to 600 ° C or more 8
A method for producing an electric resistance welded steel pipe having excellent low-temperature toughness, which comprises heating to 00 ° C. or lower and tempering.
【０００６】[0006]
【作用】以下この発明について詳細に説明する。まず素
材成分の限定理由について説明する。Ｃは強度を確保す
るための元素であるが、含有量が増えると靭性が劣化す
るため０．０１〜０．１０重量％とした。The present invention will be described in detail below. First, the reasons for limiting the material components will be described. C is an element for ensuring strength, but if the content increases, the toughness deteriorates, so 0.01 to 0.10% by weight was set.
【０００７】Ｓｉも強度確保のための必要元素である
が、０．５重量％を超えると溶接部にペネトレータが発
生しやすくなり靭性が劣化するため０．５重量％以下と
した。Ｍｎも強度を保つための必要元素であるが、０．
５重量％未満では必要強度が得られず、２．０重量％を
超えるとＳｉと同様に溶接部にペネトレータが発生しや
すくなるため０．５〜２．０重量％とした。Si is also a necessary element for securing strength, but if it exceeds 0.5% by weight, penetrators are easily generated in the welded portion and the toughness deteriorates, so it was made 0.5% by weight or less. Mn is also a necessary element for maintaining strength, but
If it is less than 5% by weight, the required strength cannot be obtained, and if it exceeds 2.0% by weight, a penetrator is likely to be generated in the welded portion like Si, so the content is set to 0.5 to 2.0% by weight.
【０００８】Ｐは偏析を生じて靭性を劣化させる元素な
ので低い方が望ましく、０．０３０重量％以下とした。
さらに耐サワー性を考慮する場合には、Ｐは０．０１０
重量％以下が望ましい。ＳはＭｎＳの介在物が靭性に影
響を及ぼすため低いほうが望ましく、０．００８重量％
以下とした。さらにＭｎＳはＨＩＣの起点となるので、
Ｓは耐サワー性確保の点からは極力低く押さえて、０．
００３重量％以下が望ましい。Since P is an element which causes segregation and deteriorates the toughness, it is desirable that the content of P be low, and the content was made 0.030% by weight or less.
When considering sour resistance, P is 0.010.
Weight% or less is desirable. Since MnS inclusions affect the toughness, it is desirable that the content of S be as low as 0.008% by weight.
Below. Furthermore, since MnS becomes the starting point of HIC,
S is kept as low as possible from the viewpoint of ensuring sour resistance, and 0.
It is preferably 003% by weight or less.
【０００９】Ｎはサイジング工程で加工を受けた際、歪
時効による靭性劣化の原因となるための低いほうがよ
く、０．０１重量％以下とした。ＡｌはＡｌＮとしてオ
ーステナイト粒を細粒化する効果が大きいが、０．０６
重量％を超えると介在物が増加し欠陥の原因となるため
０．０６重量％以下とした。N is preferably low so that it causes toughness deterioration due to strain aging when subjected to processing in the sizing step, and is set to 0.01% by weight or less. Al has a large effect of refining austenite grains as AlN, but 0.06
If the content is more than 10% by weight, inclusions increase and cause defects.
【００１０】Ｎｂ，Ｖ，Ｔｉについては、強度確保及び
結晶粒微細化のために必要な元素であり、Ｎｂ，Ｖは
０．１重量％以下、Ｔｉは０．０５重量％以下とした。
次に、熱処理条件について説明する。電縫溶接後の加熱
温度をＡｃ3 変態点以上、１０５０℃以下の範囲に限定
したのは、電縫溶接直後の靭性の劣化した急冷組織を消
去するためＡｃ3 変態点以上に加熱してオーステナイト
組織にする必要があるが、誘導加熱などによる外面側一
方向からの急速加熱の場合、加熱温度がＡｃ3 変態点未
満では内面側まで十分焼きならしができず、一方加熱温
度が１０５０℃を越えると結晶粒が粗大化し靭性が劣化
するためである。Nb, V, and Ti are elements necessary for securing strength and refining crystal grains, and Nb, V are 0.1 wt% or less and Ti are 0.05 wt% or less.
Next, heat treatment conditions will be described. The heating temperature after electric resistance welding is limited to the range of Ac 3 transformation point or more and 1050 ° C. or less in order to eliminate the quenched structure with deteriorated toughness immediately after electric resistance welding and to heat it to the Ac 3 transformation point or more to austenite. Although it is necessary to form a structure, in the case of rapid heating from one direction on the outer surface side by induction heating or the like, if the heating temperature is below the Ac 3 transformation point, normalizing to the inner surface side is not sufficient, while the heating temperature is 1050 ° C. This is because if it exceeds, the crystal grains become coarse and the toughness deteriorates.
【００１１】その後の冷却条件について、冷却開始温度
を８００℃以上としたのは、冷却開始温度が８００℃よ
り低くなると組織の整粒均一化が行われず急冷の効果が
なくなるためである。冷却速度の限定理由は、冷却速度
が１０℃／ｓｅｃより遅いと結晶粒が粗大化してしま
い、靭性が劣化するためであり、一方冷却速度が例えば
図４に示すようなＣＣＴ曲線（連続冷却変態曲線）で決
まるフェライトが析出する範囲の冷却速度を越えると外
面側がベーナイト或いはマルテンサイトの脆化組織とな
り好ましくないためである。Regarding the subsequent cooling conditions, the reason why the cooling start temperature is set to 800 ° C. or higher is that if the cooling start temperature is lower than 800 ° C., grain size uniformization of the structure is not performed and the effect of rapid cooling is lost. The reason for limiting the cooling rate is that if the cooling rate is slower than 10 ° C./sec, the crystal grains become coarse and the toughness deteriorates. On the other hand, the cooling rate is, for example, the CCT curve (continuous cooling transformation shown in FIG. 4). This is because if the cooling rate in the range in which ferrite determined by the curve) is exceeded, the outer surface side becomes an embrittlement structure of bainite or martensite, which is not preferable.
【００１２】冷却停止温度を（Ａｒ1 変態点＋１００
℃）以下（Ａｒ1 変態点−１００℃）以上の温度とし、
その後空冷にて４００℃以下まで冷却する理由について
述べる。冷却停止とそれに引き続いて空冷する目的はＣ
が濃化した微小な未変態γ域が急冷によって低温変態
し、ベーナイト或いはマルテンサイトの脆化組織となる
のを防ぐことにある。冷却停止温度が（Ａｒ1 変態点＋
１００℃）を越えるとフェライトの細粒化の効果がなく
なる。一方冷却停止温度が（Ａｒ1 変態点−１００℃）
より低くなるか、或いは冷却停止後の冷却速度が空冷よ
り速い場合、Ｃが濃化した微小な未変態γ域がベーナイ
ト或いはマルテンサイトとなり外面側が硬化してしま
う。また空冷にて４００℃以下まで冷却するのは、全体
の組織を変態完了させ安定化するためである。従って、
細粒化をしつつ、外面側の硬化が起こらないように組織
を調整するには冷却停止温度を（Ａｒ1 変態点＋１００
℃）以下（Ａｒ1 変態点−１００℃）以上にし、その後
空冷にて４００℃以下まで冷却する必要がある。The cooling stop temperature is (Ar 1 transformation point +100
℃) or less (Ar 1 transformation point -100 ℃) or more,
Then, the reason for cooling to 400 ° C. or lower by air cooling will be described. The purpose of the cooling stop and the subsequent air cooling is C
The purpose of this is to prevent the minute untransformed γ region in which is concentrated from being transformed at low temperature by rapid cooling and becoming a brittle structure of bainite or martensite. The cooling stop temperature is (Ar 1 transformation point +
If the temperature exceeds 100 ° C., the effect of refining the ferrite is lost. On the other hand, the cooling stop temperature is (Ar 1 transformation point −100 ° C.)
If it becomes lower or the cooling rate after cooling is faster than air cooling, the minute untransformed γ region in which C is concentrated becomes bainite or martensite, and the outer surface side is hardened. Further, the reason for cooling to 400 ° C. or lower by air cooling is to complete the transformation and stabilize the entire structure. Therefore,
In order to adjust the structure so that hardening on the outer surface side does not occur while making the grains fine, the cooling stop temperature is set to (Ar 1 transformation point +100
C.) or lower (Ar 1 transformation point −100 ° C.) or higher, and then air cooling to 400 ° C. or lower is required.
【００１３】最終の加熱温度を６００℃〜８００℃の範
囲に限定したのは、６００℃未満ではシーム近傍の２相
加熱域の硬度があまり低下しないため十分な焼戻し効果
が得られず、一方８００℃を越えるとフェライト結晶粒
が粗大化して靭性が劣化するためである。The final heating temperature is limited to the range of 600 ° C. to 800 ° C. When the temperature is less than 600 ° C., the hardness of the two-phase heating region near the seam does not decrease so much that a sufficient tempering effect cannot be obtained. This is because if the temperature exceeds ° C, the ferrite crystal grains become coarse and the toughness deteriorates.
【００１４】[0014]
【実施例】本発明を実施する電縫管製造設備の概略を図
１に示す。連続的に成形された鋼帯１はエッジを溶接電
極３で加熱され、スクイズロール４で加圧、接合され、
電縫溶接部２をもつ電縫管９となる。この電縫溶接部２
は誘導加熱装置５，６によって所定温度まで加熱された
後、水冷装置８により外面側から所定の冷却速度で冷却
を施され、所定温度にて冷却停止した後空冷にて４００
℃以下まで冷却され、さらに誘導加熱装置７で再加熱さ
れ、焼戻し処理が施される。EXAMPLE An outline of an electric resistance welded pipe manufacturing facility for carrying out the present invention is shown in FIG. The edge of the continuously formed steel strip 1 is heated by the welding electrode 3 and is pressed and joined by the squeeze roll 4.
The electric resistance welded pipe 9 has the electric resistance welded portion 2. This electric resistance welded part 2
Is heated to a predetermined temperature by the induction heating devices 5 and 6, and then cooled by the water cooling device 8 from the outer surface side at a predetermined cooling rate.
It is cooled to below ℃, is reheated by the induction heating device 7, and is tempered.
【００１５】次に、本発明の加熱冷却パターンの一例を
図２に示す。電縫溶接部をＡｃ3 変態点（９００℃）以
上１０５０℃以下に加熱し、８００℃以上の温度から鋼
種に応じた所定の冷却速度で冷却し、（Ａｒ1 変態点＋
１００℃）以下（Ａｒ1 変態点−１００℃）以上の範囲
で冷却停止の後空冷に移行するが、冷却停止直後は復熱
により外面の温度が一旦上昇しその後下降する。この空
冷時の冷却速度は１〜６℃／ｓｅｃである。空冷の状態
で４００℃以下まで冷却し組織が変態完了した後に、再
度６００℃〜８００℃に加熱し焼戻し処理により２相加
熱域の硬度を下げる。以上のように制御冷却時の冷却速
度、冷却停止温度を限定しその後空冷、焼戻しを加える
ことによって優れた溶接部低温靭性と均一な材質が得ら
れる。Next, an example of the heating / cooling pattern of the present invention is shown in FIG. The electric resistance welded portion is heated to a temperature of Ac 3 transformation point (900 ° C.) or higher and 1050 ° C. or lower, and cooled at a predetermined cooling rate according to the steel type from a temperature of 800 ° C. or higher, (Ar 1 transformation point +
In the range of 100 ° C. or lower (Ar 1 transformation point−100 ° C.) or higher, cooling is stopped and then air cooling is performed, but immediately after cooling is stopped, the temperature of the outer surface rises once due to heat recovery and then falls. The cooling rate during this air cooling is 1 to 6 ° C./sec. After cooling to 400 ° C. or less in the air-cooled state to complete the transformation of the structure, it is heated again to 600 ° C. to 800 ° C. and tempered to reduce the hardness of the two-phase heating region. As described above, excellent low temperature toughness of the weld zone and uniform material can be obtained by limiting the cooling rate and the cooling stop temperature during controlled cooling and then performing air cooling and tempering.
【００１６】表１に示される化学成分組成の鋼を用い、
図１に概略を示す装置を用いて、電縫溶接と熱処理を実
施し、外径５０８ｍｍφ、肉厚１２．７ｍｍの電縫鋼管
を製造した。このようにして製造された電縫鋼管の溶接
部から、１０ｍｍ×１０ｍｍ、２Ｖノッチのシャルピー
試験片を切り出して試験を実施し、シャルピー遷移曲線
から破面遷移温度を調査した。また合せて溶接部の硬度
分布も測定した。Using steel having the chemical composition shown in Table 1,
Using the apparatus schematically shown in FIG. 1, electric resistance welding and heat treatment were performed to manufacture an electric resistance welded steel pipe having an outer diameter of 508 mmφ and a wall thickness of 12.7 mm. A Charpy test piece of 10 mm × 10 mm, 2V notch was cut out from the welded portion of the electric resistance welded steel pipe manufactured in this manner, a test was performed, and a fracture surface transition temperature was investigated from a Charpy transition curve. In addition, the hardness distribution of the welded portion was also measured.
【００１７】表２に溶接部の熱処理条件と溶接部シャル
ピー衝撃試験による遷移温度を示す。表２には合せてフ
ェライトが析出する臨界冷却速度も示してある。本発明
によれば従来法に比べて靭性が良好であることがわか
る。次にシーム近傍の外面側硬度分布の一例を図３に示
す。全般的にシーム部及び２相加熱域の硬度が高いが、
本発明によれば従来法に比べてこの部分の母材との硬度
差が小さく、シーム近傍全体に亘って均一な材質が得ら
れていることがわかる。Table 2 shows the heat treatment conditions of the weld zone and the transition temperature of the weld zone Charpy impact test. Table 2 also shows the critical cooling rate at which ferrite precipitates. According to the present invention, it is found that the toughness is better than that of the conventional method. Next, an example of the hardness distribution on the outer surface side near the seam is shown in FIG. Generally, the hardness of the seam part and the two-phase heating area is high,
According to the present invention, it is found that the difference in hardness from the base material in this portion is smaller than that in the conventional method, and a uniform material is obtained over the entire vicinity of the seam.
【００１８】[0018]
【表１】 [Table 1]
【００１９】[0019]
【表２】 [Table 2]
【００２０】[0020]
【発明の効果】以上の結果から明らかなように、本発明
法により従来法に比べて溶接部低温靭性に優れ、シーム
及びその近傍全体に亘って母材と同等の硬度を有する均
質な材質の電縫鋼管の製造が可能である。As is clear from the above results, according to the method of the present invention, the low temperature toughness of the welded portion is superior to that of the conventional method, and a homogeneous material having the same hardness as the base metal is provided over the entire seam and its vicinity. ERW steel pipe can be manufactured.
【図１】本発明を実施する電縫鋼管製造設備の概略図で
ある。FIG. 1 is a schematic view of an electric resistance welded steel pipe manufacturing facility for carrying out the present invention.
【図２】本発明法の加熱冷却パターンの一例を示す図で
ある。FIG. 2 is a diagram showing an example of a heating / cooling pattern of the method of the present invention.
【図３】本発明の効果を示すグラフである。FIG. 3 is a graph showing the effect of the present invention.
【図４】ＣＣＴ曲線の例を示す図である。FIG. 4 is a diagram showing an example of a CCT curve.
１ 鋼帯 ２ 電縫溶
接部 ３ 溶接電極 ４ スクイ
ズロール ５，６，７ 誘導加熱装置 ８ 水冷装
置 ９ 電縫管1 Steel strip 2 ERW welded part 3 Welding electrode 4 Squeeze roll 5, 6, 7 Induction heating device 8 Water cooling device 9 ERW pipe
Claims (1)
物よりなる帯鋼を連続的に成形した後に電縫溶接し、こ
れに引き続いて溶接部をＡｃ3 変態点以上、１０５０℃
以下に加熱した後、８００℃以上の温度から（Ａｒ1 変
態点＋１００℃）以下（Ａｒ1 変態点−１００℃）以上
の温度範囲の所定温度まで１０℃／ｓｅｃ以上かつ前記
鋼のＣＣＴ曲線から求まるフェライトが析出する冷却速
度で強制冷却し、引続きその温度から４００℃以下まで
空冷した後に、再び該溶接部を６００℃以上８００℃以
下に加熱して焼戻すことを特徴とする低温靭性に優れた
電縫鋼管の製造方法。1. C: 0.01 to 0.10% by weight, Si: 0.5% by weight or less, Mn: 0.5 to 2.0% by weight, P: 0.030% by weight or less, S: 0. 0.008 wt% or less, N: 0.01 wt% or less, Al: 0.06 wt% or less, and Nb: 0.1 wt% or less, V: 0.1 wt% or less, Ti: 0.05 A steel strip containing at least one of the following components by weight and having the balance Fe and unavoidable impurities is continuously formed and then electric resistance welded. Subsequently, the welded portion is at the Ac 3 transformation point or higher and 1050 ° C.
After heating below, from a temperature of 800 ° C. or higher to a predetermined temperature in a temperature range of (Ar 1 transformation point + 100 ° C.) or lower (Ar 1 transformation point−100 ° C.) or higher, 10 ° C./sec or more and from the CCT curve of the steel. Excellent low-temperature toughness, characterized by performing forced cooling at the cooling rate at which the required ferrite precipitates, subsequently air-cooling from that temperature to 400 ° C or less, and then heating the welded portion to 600 ° C or more and 800 ° C or less again and tempering. ERW steel pipe manufacturing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13065892A JPH05320775A (en) | 1992-05-22 | 1992-05-22 | Production of electric resistance welded steel tube excellent in low temperature toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP13065892A JPH05320775A (en) | 1992-05-22 | 1992-05-22 | Production of electric resistance welded steel tube excellent in low temperature toughness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05320775A true JPH05320775A (en) | 1993-12-03 |
Family
ID=15039517
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13065892A Withdrawn JPH05320775A (en) | 1992-05-22 | 1992-05-22 | Production of electric resistance welded steel tube excellent in low temperature toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05320775A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998048061A1 (en) * | 1997-04-17 | 1998-10-29 | Aspector Oy | Heat treatment of steel |
| JP2006299413A (en) * | 2005-03-24 | 2006-11-02 | Jfe Steel Kk | Method for producing low yield-ratio electric-resistance welded steel tube excellent in low temperature toughness |
-
1992
- 1992-05-22 JP JP13065892A patent/JPH05320775A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1998048061A1 (en) * | 1997-04-17 | 1998-10-29 | Aspector Oy | Heat treatment of steel |
| JP2006299413A (en) * | 2005-03-24 | 2006-11-02 | Jfe Steel Kk | Method for producing low yield-ratio electric-resistance welded steel tube excellent in low temperature toughness |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19990803 |