JP3243659B2 - Manufacturing method of coiled steel pipe with excellent cold workability - Google Patents
Manufacturing method of coiled steel pipe with excellent cold workabilityInfo
- Publication number
- JP3243659B2 JP3243659B2 JP02713593A JP2713593A JP3243659B2 JP 3243659 B2 JP3243659 B2 JP 3243659B2 JP 02713593 A JP02713593 A JP 02713593A JP 2713593 A JP2713593 A JP 2713593A JP 3243659 B2 JP3243659 B2 JP 3243659B2
- Authority
- JP
- Japan
- Prior art keywords
- rolling
- steel pipe
- hot
- coiled steel
- cold workability
- 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.)
- Expired - Fee Related
Links
Landscapes
- Heat Treatment Of Steel (AREA)
- Winding, Rewinding, Material Storage Devices (AREA)
Description
【0001】[0001]
【産業上の利用分野】本発明は、自動車または産業機械
部品用、地熱用、化学プラント用、石油または天然ガス
用油井管、一般配管用などに使用するコイル状鋼管の製
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 a coiled steel pipe used for automobile or industrial machine parts, geothermal, chemical plants, oil well pipes for petroleum or natural gas, and general pipes. .
【0002】[0002]
【従来の技術】コイル状鋼管は、鍛接鋼管、電縫溶接鋼
管、シームレス鋼管等を素管として熱間ストレッチレデ
ューサーにより絞り圧延した後、コイル状に巻き取り製
造されている。その後、該コイル状鋼管は、引き抜き加
工、転造加工、ネジ切削加工等の二次加工処理し、各種
配管及び機械部品等に使用されている。2. Description of the Related Art A coiled steel pipe is produced by rolling a forged steel pipe, an electric resistance welded steel pipe, a seamless steel pipe, or the like as a raw pipe by a hot stretch reducer, and then winding it into a coil. Thereafter, the coiled steel pipe is subjected to secondary processing such as drawing, rolling, and screw cutting, and is used for various pipes and machine parts.
【0003】該コイル状鋼管の金属組織は、特開昭50
−16657号、特開昭60−125326号、及び特
開昭60−137510号公報に記載されている如くフ
ェライト+パーライトを有する焼鈍組織である。該フェ
ライト+パーライト組織を有する材料は耐冷間加工性が
悪い。そのため高度の冷間加工性が要求される自動車、
産業機械部品用等の材料は、通常球状化焼鈍処理材料が
使用されている。[0003] The metallographic structure of the coiled steel pipe is disclosed in
This is an annealed structure having ferrite and pearlite as described in JP-A-16657, JP-A-60-125326, and JP-A-60-137510. The material having the ferrite + pearlite structure has poor cold work resistance. Therefore, automobiles that require a high degree of cold workability,
As materials for industrial machine parts and the like, spheroidizing annealing materials are usually used.
【0004】該球状化処理法としてAc1点以上に加熱し
たのち徐冷する方法や、Ac1点上下の温度に加熱冷却を
繰り返す方法が実施されている。しかし、前記の球状化
焼鈍処理は数10時間の長い処理時間を要し、熱処理コ
ストの増大や脱炭、酸化の品質課題があり、従来から焼
鈍前に冷間引抜加工を施して焼鈍時間の短縮を図ってい
るが、満足な効果が得られていない。[0004] As the spheroidizing method, a method of heating to more than one point of Ac and then gradually cooling, and a method of repeating heating and cooling to a temperature above and below one point of Ac are implemented. However, the above-described spheroidizing annealing requires a long processing time of several tens of hours, and has a problem of quality increase in heat treatment cost and decarburization and oxidation. Conventionally, cold drawing is performed before annealing to reduce the annealing time. Despite shortening, satisfactory results have not been obtained.
【0005】[0005]
【発明が解決しようとする課題】本発明は、前記の問題
点を解決するために、コイル状鋼管の金属組織を球状化
して冷間加工性を向上させ、かつ、前記処理を効率よく
低コストで得ることを目的としている。SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is to improve the cold workability by spheroidizing the metal structure of a coiled steel pipe, and to reduce the cost of the treatment efficiently. The goal is to get in.
【0006】[0006]
【課題を解決するための手段・作用】本発明は、熱間絞
り圧延して得られたコイル状鋼管の金属組織が球状化組
織を呈し、且つ該球状化処理コストが安価であることを
特徴とする冷間加工性の優れたコイル状鋼管の製造方法
を提供することを目的とするものである。The present invention is characterized in that the metal structure of the coiled steel pipe obtained by hot drawing and rolling exhibits a spheroidized structure, and the cost of the spheroidizing treatment is low. It is an object of the present invention to provide a method for producing a coiled steel pipe having excellent cold workability.
【0007】本発明のコイル状鋼管は、圧延終了温度、
圧延終了後の冷却温度を特定の範囲に制御することによ
り微細パーライト、微細ベイナイト若しくはこれらの混
合組織とし、微細組織は再加熱炉4で熱処理する際、該
微細処理組織中の炭化物が球状化組織の核となり短時間
で容易に球状化組織となる。そのため球状化熱処理コス
トが低減し、更に冷間加工性等の材質特性が著しく優れ
ている。[0007] The coiled steel pipe of the present invention has a rolling end temperature,
By controlling the cooling temperature after rolling to a specific range, fine pearlite , fine bainite, or a mixed structure thereof is formed. When the fine structure is heat-treated in the reheating furnace 4, the carbide in the finely processed structure becomes spheroidized And easily become a spheroidized tissue in a short time. Therefore, the cost of spheroidizing heat treatment is reduced, and the material properties such as cold workability are remarkably excellent.
【0008】本発明の要旨とするところは、熱間絞り圧
延してコイル状鋼管を製造する際に、熱間絞り圧延用素
管を900〜1100℃に加熱し、続いて該素管のAr3
点以下(以下単にAr3点以下と称する)、(Ar3−10
0℃)以上の温度域で熱間絞り圧延を行い、続いて熱間
絞り圧延終了温度からAr1−200℃の温度範囲を10
〜40℃/sec の冷却速度で冷却し、続いてAc1以下、
(Ac1−50℃)以上の温度域に再加熱してコイル状に
巻き取ることを特徴とする冷間加工性の優れたコイル状
鋼管の製造方法である。The gist of the present invention is that when a coiled steel pipe is manufactured by hot drawing and rolling, the raw tube for hot drawing and rolling is heated to 900 to 1100 ° C. Three
Point below (hereinafter simply referred to as the following 3 points Ar), (Ar 3 -10
Performed hot reducing rolling at 0 ° C.) or higher temperature range, followed by a temperature range of Ar 1 -200 ° C. from the hot reducing rolling end temperature of 10
Cooling at a cooling rate of to 40 ° C. / sec, followed by Ac 1 or less,
A method for producing a coiled steel pipe having excellent cold workability, characterized by reheating to a temperature range of (Ac 1 -50 ° C.) or higher and winding the coil into a coil.
【0009】以下に本発明の製造方法及び設備構成につ
いて述べる。本発明のコイル状鋼管の製造方法は、図1
に一例を示すように圧延用素管11を900〜1100
℃に加熱炉1で加熱し、該圧延用素管11の熱間絞り圧
延をAr3点以下、(Ar3−100℃)以上の温度域で終
了させる。Hereinafter, the production method and the equipment configuration of the present invention will be described. The method for manufacturing a coiled steel pipe of the present invention is shown in FIG.
As shown in FIG.
° C. to heating in a heating furnace 1, a hot reducing rolling of the rolling pipe for 11 Ar 3 point or less, it is terminated in a temperature range of not lower than (Ar 3 -100 ℃).
【0010】その際、Ar3点で初析フェライト粒が析出
する。該初析フェライト粒は、(Ar3−100℃)間で
熱間絞り圧延で内部に歪が蓄積された延伸フェライト粒
になる。延伸フェライト粒は、未変態オーステナイト相
がAr1変態する際、変態生成核となり、微細な析出物状
及び微細なパーライト組織が得られる。続いて該圧延管
12を冷却装置3で熱間絞り圧延終了温度からAr1−2
00℃の温度範囲を10〜40℃/sec の冷却速度で冷
却し、該強制冷却した圧延管12を再加熱炉4でAc1点
以下、(Ac1−50℃)以上の温度域に再加熱してコイ
ル状に巻き取ることによりコイル状鋼管を製造する。At this time, proeutectoid ferrite grains are precipitated at three Ar points. The pro-eutectoid ferrite grains become elongated ferrite grains in which strain is accumulated inside by hot-draw rolling between (Ar 3 -100 ° C.). The stretched ferrite grains serve as transformation nuclei when the untransformed austenite phase is transformed into Ar 1 , and a fine precipitate and a fine pearlite structure are obtained. Subsequently, the rolling tube 12 is cooled by the cooling device 3 from the hot-rolling end temperature to Ar 1-2.
The temperature range of 00 ° C. is cooled at a cooling rate of 10 to 40 ° C./sec, and the forcibly cooled rolling tube 12 is re-heated to a temperature range of one point Ac or less and (Ac 1 -50 ° C.) or more in the reheating furnace 4. The coiled steel pipe is manufactured by heating and winding it into a coil.
【0011】該Ar3、およびAr1点に関して、本発明者
らは数多くの実験を重ねた結果、式(1)及び式(2)
に示すように鋼中の化学成分組成とAr3、Ar1点の関係
を求めた。 Ar3=827−64C−33Si−19Mn+17Cr−48Mo・・・・(1)式 Ar1=686−2C−0.4Si−30Mn+40Cr−85Mo・・・・(2)式 Ac1=723 ・・・・(3)式As for the Ar 3 and Ar 1 points, the present inventors have conducted a number of experiments and found that the equations (1) and (2)
As shown in Table 2 , the relationship between the chemical composition of the steel and Ar 3 and Ar 1 point was determined. Ar 3 = 827−64C−33Si−19Mn + 17Cr−48Mo (1) Formula Ar 1 = 686−2C−0.4Si−30Mn + 40Cr−85Mo (2) Formula Ac 1 = 723 (・ ・ ・) 3) Formula
【0012】圧延素管11は炭素鋼からなる鋼管であ
り、マンネスマン各種方式によって製造されたシームレ
ス鋼管、熱間押出鋼管、電縫溶接鋼管、鍛接鋼管等を用
いることができる。圧延素管11を加熱する加熱炉1と
しては、バレル炉、ウォーキングビーム炉及び誘導加熱
炉等を用いることができる。熱間絞り加工された管を加
熱して鋼中炭化物を凝集させる再加熱炉4としては、誘
導加熱炉等を用いることができる。The rolled raw pipe 11 is a steel pipe made of carbon steel, and may be a seamless steel pipe, a hot extruded steel pipe, an electric resistance welded steel pipe, a forged steel pipe, or the like manufactured by various Mannesmann methods. As the heating furnace 1 for heating the rolling element tube 11, a barrel furnace, a walking beam furnace, an induction heating furnace, or the like can be used. An induction heating furnace or the like can be used as the reheating furnace 4 that heats the hot drawn pipe to aggregate carbides in steel.
【0013】ストレッチレデューサー2は、2ロール又
は3ロールのロールハウジングを連続的に10〜30ス
タンド配列した圧延機であり、素管11は外径が順次圧
延されながら相隣するスタンド間の周速の差によって軸
方向に延伸されて、所望の外径、肉厚となった圧延管1
2は、冷却装置3で強制冷却され、続いて強制冷却され
た圧延管12は再加熱炉4で再加熱され、ピンチローラ
ー5で誘導され、巻取機6で巻き取られてコイル状鋼管
13となる。The stretch reducer 2 is a rolling mill in which roll housings of 2 rolls or 3 rolls are continuously arranged in 10 to 30 stands, and the raw tube 11 has a peripheral speed between adjacent stands while the outer diameter is sequentially rolled. Rolled tube 1 which has been stretched in the axial direction by the difference in
The rolled tube 2 is forcibly cooled by the cooling device 3, and subsequently the rolled tube 12 that has been forcibly cooled is reheated by the reheating furnace 4, guided by the pinch roller 5, wound up by the winder 6, and wound into the coiled steel tube 13. Becomes
【0014】本発明の構成の限定理由は以下の通りであ
る。熱間圧延用鋼管を熱間圧延絞り圧延してコイル状鋼
管を製造する際に、圧延用素管を900〜1100℃に
加熱し、続いて熱間絞り圧延する際、該熱間絞り圧延終
了温度をAr 3 点以下に限定したのは、図2に熱間絞り
圧延パターンを示す如く、熱間絞り圧延終了がAr3点
以上では再結晶した整粒のオーステナイト相となり、そ
の後Ar3、Ar1変態で粗粒のフェライト組織とパー
ライト組織に変態し、以後の鋼中炭化物を凝集させる再
加熱炉4で熱処理しても目的とする球状化組織が得られ
ない。The reasons for limiting the configuration of the present invention are as follows. When the hot rolled steel pipe is hot-rolled and drawn to produce a coiled steel pipe, the raw rolled tube is heated to 900 to 1100 ° C., and when the hot-rolled steel is subsequently hot-rolled, the hot-rolled rolling is completed. The reason why the temperature was limited to Ar 3 points or less is that, as shown in the hot-rolling rolling pattern in FIG. 2, when the hot-rolling rolling was completed at Ar 3 points or more, the recrystallized and sized austenite phase, and then Ar 3 and Ar In one transformation, it is transformed into a coarse ferrite structure and a pearlite structure, and even if it is heat-treated in a reheating furnace 4 for agglomerating carbide in steel thereafter, the desired spheroidized structure cannot be obtained.
【0015】また(Ar3−100℃)以上に限定したの
は、熱間絞り圧延終了温度が(Ar3−100℃)以下に
なると熱間絞り圧延中または熱間絞り圧延後冷却中にオ
ーステナイト相がマルテンサイト組織叉はベイナイト組
織に変態し、変態抵抗が大きくなり熱間絞り圧延に支障
を来す。前記理由により熱間絞り圧延終了温度を(Ar3
−100℃)以上に限定した。The reason why the temperature is limited to (Ar 3 -100 ° C.) or higher is that when the hot-rolling end temperature is equal to or lower than (Ar 3 -100 ° C.), austenite is reduced during hot-rolling rolling or during cooling after hot-rolling rolling. The phase transforms into a martensite structure or a bainite structure, and the transformation resistance increases, which hinders hot-drawing rolling. For the above reason, the hot-rolling rolling end temperature is set to (Ar 3
(−100 ° C.) or higher.
【0016】次に熱間圧延管を冷却する過冷オーステナ
イト温度に関し、発明者等は数多くの実験を行った結
果、次工程での球状化処理が容易な微細パーライト組
織、微細ベイナイト組織の混合組織(ツビィッセン組
織)を得るには、熱間絞り圧延終了温度から(Ar1−2
00℃)の温度範囲を10℃/sec 〜40℃/sec 以下
の冷却速度で冷却することであることを見いだした。Next, as for the supercooled austenite temperature for cooling the hot-rolled tube, the inventors conducted a number of experiments and found that a mixed structure of a fine pearlite structure and a fine bainite structure that can be easily spheroidized in the next step. In order to obtain a (Zweisssen structure), (Ar 1-2 ) is determined from the hot-rolling end temperature.
(00 ° C.) at a cooling rate of 10 ° C./sec to 40 ° C./sec or less.
【0017】即ち、該冷却終了温度が(Ar1−200
℃)を超える温度から40℃/sec を超える冷却速度で
冷却すると未変態オーステナイト相がマルテンサイト相
組織に変態し、一方、10℃/sec 未満の冷却速度では
粗粒パーライトに変態するため微細パーライト、微細ベ
イナイトあるいはこれらの混合組織が得られない。この
理由により熱間圧延管を強制冷却する際、冷却速度は1
0℃/sec から40℃/sec 以下、冷却終了温度は(A
r1−200℃)以下の範囲に限定した。That is, the cooling end temperature is (Ar 1 -200
When the cooling rate is higher than 40 ° C./sec, the untransformed austenite phase is transformed into a martensitic phase structure when the cooling rate is lower than 10 ° C./sec. , Fine bainite or a mixed structure thereof cannot be obtained. For this reason, when forcibly cooling the hot rolled tube, the cooling rate is 1
0 ° C / sec to 40 ° C / sec or less, the cooling end temperature is (A
r 1 -200 ° C.)
【0018】次に熱間絞り圧延後、強制冷却した圧延鋼
管を再加熱する温度領域をAc1点以下、(Ac1−50
℃)以上までに限定したのは、Ac1点以上に加熱すると
鋼中の炭化物は分解固溶して球状化の効果をもたらさな
い。また(Ac1−50℃)以下の温度では鋼中の炭素の
拡散が充分におこらないため炭化物の凝集が行われない
ため加熱温度をAc1点以下、(Ac1−50℃)以上に限
定した。Next, after the hot drawing rolling, the temperature range in which the forcibly cooled rolled steel pipe is reheated is set to 1 point or less of Ac, (Ac 1 -50
C)) or more, the carbide in steel is decomposed and solid-dissolved when heated to more than 1 point of Ac, and does not bring about the effect of spheroidization. At a temperature below (Ac 1 -50 ° C.), diffusion of carbon in the steel does not occur sufficiently, so that carbides are not agglomerated. Therefore, the heating temperature is limited to below the Ac 1 point and above (Ac 1 -50 ° C.). .
【0019】[0019]
【実施例】以下に、本発明の実施例についてその効果を
述べる。表1に示す各種組成の炭素鋼を用いて、熱間圧
延温度、圧延終了温度、圧延終了後の冷却温度及び再加
熱温度をかえて製造したコイル状鋼管の品質特性、即ち
金属組織、圧縮加工特性を評価した結果を示す。The effects of the embodiments of the present invention will be described below. Quality characteristics of coiled steel pipes manufactured using carbon steels of various compositions shown in Table 1 by changing the hot rolling temperature, the rolling end temperature, the cooling temperature after the rolling end, and the reheating temperature, ie, metal structure, compression working The results of evaluating the characteristics are shown.
【表1】 本発明による製造方法によれば、球状化組織は
従来法の如き長時間処理を必要とせず短時間処理ですみ
且つ得られたコイル状鋼管の限界圧縮率は高く、従来の
該コイル状鋼管に比して大幅に冷間加工性が向上する。 [Table 1] According to the production method of the present invention, the spheroidized structure can be processed in a short time without requiring a long time treatment as in the conventional method, and the obtained coiled steel pipe has a high critical compression ratio. Cold workability is greatly improved compared to coiled steel pipes.
【0020】[0020]
【発明の効果】本発明により製造されたコイル状鋼管
は、短時間で球状化処理が可能であり、該球状化処理コ
ストが低廉する。且つ優れた冷間加工性を有し、更に該
コイル状鋼管の長手方向および円周方向の材質特性は均
質であり、従来の該コイル状鋼管に比し、品質特性を飛
躍的に向上させるものであり、工業的価値は絶大であ
る。According to the present invention, the coiled steel pipe manufactured according to the present invention can be subjected to spheroidizing treatment in a short time, and the spheroidizing treatment cost is reduced. It also has excellent cold workability, and the material properties of the coiled steel pipe in the longitudinal and circumferential directions are uniform, and the quality characteristics are dramatically improved as compared with the conventional coiled steel pipe. And the industrial value is enormous.
【図1】本発明のコイル状鋼管の製造設備の一例を示す
図である。FIG. 1 is a diagram showing an example of a facility for manufacturing a coiled steel pipe of the present invention.
【図2】本発明と従来例の熱間絞圧延パターンを示す図
である。FIG. 2 is a diagram showing hot reduction rolling patterns of the present invention and a conventional example.
1 加熱炉 2 ストレッチレデューサー 3 冷却装置 4 再加熱炉 5 ピンチロール 6 巻取機 11 圧延用素管 12 圧延管 13 コイル状鋼管 DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Stretch reducer 3 Cooling device 4 Reheating furnace 5 Pinch roll 6 Winder 11 Rolling tube 12 Rolling tube 13 Coiled steel tube
【表1】 [Table 1]
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭60−125326(JP,A) 特開 平1−283321(JP,A) 特開 平5−247532(JP,A) (58)調査した分野(Int.Cl.7,DB名) C21D 8/10 B21B 17/14 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-125326 (JP, A) JP-A-1-283321 (JP, A) JP-A-5-247532 (JP, A) (58) Field (Int.Cl. 7 , DB name) C21D 8/10 B21B 17/14
Claims (1)
際に、熱間絞り圧延用素管を900〜1100℃に加熱
し、続いて該素管のAr3点以下、(Ar3−100
℃)以上の温度で熱間絞り圧延を終了し、続いて熱間絞
り圧延終了温度からAr1−200℃の温度範囲を10
〜40℃/sec の冷却速度で冷却し、続いてAc1
点以下、(Ac1−50℃)以上の温度域に再加熱し、
続いてコイル状に巻き取ることを特徴とする冷間加工性
の優れたコイル状鋼管の製造方法。When a coiled steel pipe is manufactured by hot-rolling, a raw pipe for hot-rolling is heated to 900 to 1100 ° C., and then the Ar of the raw pipe is reduced to 3 points or less (Ar 3 -100
° C.) to exit the hot reducing rolling at temperatures above and subsequently the temperature range of Ar 1 -200 ° C. from the hot grain <br/> Ri rolling end temperature 10
Cooling at a cooling rate of 4040 ° C./sec followed by Ac 1
Re-heated to a temperature range of (Ac 1 -50 ° C.) or higher,
Subsequently, a method for producing a coiled steel pipe having excellent cold workability, which is wound in a coil shape.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP02713593A JP3243659B2 (en) | 1993-01-25 | 1993-01-25 | Manufacturing method of coiled steel pipe with excellent cold workability |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP02713593A JP3243659B2 (en) | 1993-01-25 | 1993-01-25 | Manufacturing method of coiled steel pipe with excellent cold workability |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH06220535A JPH06220535A (en) | 1994-08-09 |
JP3243659B2 true JP3243659B2 (en) | 2002-01-07 |
Family
ID=12212615
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP02713593A Expired - Fee Related JP3243659B2 (en) | 1993-01-25 | 1993-01-25 | Manufacturing method of coiled steel pipe with excellent cold workability |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP3243659B2 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4331300B2 (en) * | 1999-02-15 | 2009-09-16 | 日本発條株式会社 | Method for manufacturing hollow stabilizer |
JP4567907B2 (en) * | 2001-04-02 | 2010-10-27 | 新日本製鐵株式会社 | Steel pipe excellent in hydroformability and manufacturing method thereof |
JP4586313B2 (en) * | 2001-07-31 | 2010-11-24 | Jfeスチール株式会社 | Manufacturing method of high carbon seamless steel pipe with excellent secondary workability |
-
1993
- 1993-01-25 JP JP02713593A patent/JP3243659B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JPH06220535A (en) | 1994-08-09 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN101410536B (en) | Method of manufacturing seamless pipe and tube | |
US4604145A (en) | Process for production of steel bar or steel wire having an improved spheroidal structure of cementite | |
US3711338A (en) | Method for cooling and spheroidizing steel rod | |
JP2000256740A (en) | Manufacture of hot rolled wire | |
JP3243659B2 (en) | Manufacturing method of coiled steel pipe with excellent cold workability | |
JPH03240919A (en) | Production of steel wire for wiredrawing | |
JP3965708B2 (en) | Manufacturing method of high strength seamless steel pipe with excellent toughness | |
JPS63238217A (en) | Production of seamless steel pipe of martensitic stainless steel having excellent low-temperature toughness and stress corrosion cracking resistance | |
JP3355999B2 (en) | Direct softening method for hot rolled wire | |
JP3223264B2 (en) | Manufacturing method of coiled steel pipe with excellent cold workability | |
JPH06346146A (en) | Production of wire rod for cold forming coil spring and device therefor | |
JP3683378B2 (en) | Manufacturing method of high toughness and high ductility steel pipe | |
JPS644568B2 (en) | ||
JPH11172336A (en) | Production of seamless steel tube | |
JPS5913024A (en) | Manufacture of directly spheroidized steel material | |
JPH0576525B2 (en) | ||
JPS5931573B2 (en) | Direct heat treatment method for hot rolled wire rod | |
JP2792896B2 (en) | Method for producing carbon steel or alloy steel sheet having fine spheroidized carbide | |
JP2904505B2 (en) | Method of manufacturing steel wire for cold / warm forging and steel wire for cold / warm forging | |
JP3214350B2 (en) | Method for producing Cr-Mo based seamless steel pipe excellent in high temperature strength | |
JPH05117749A (en) | Production of martensitic stainless steel seamless pipe having excellent low-temperature toughness and stress corrosion cracking resistance | |
JPH10298641A (en) | Production of steel excellent in spheroidize-annealing treatability | |
JPS60149724A (en) | Manufacture of steel bar or wire rod having spheroidized structure | |
JP3613015B2 (en) | Method for producing high carbon steel sheet having high ductility and hardenability | |
JP4132695B2 (en) | Reduced diameter rolled steel pipe and manufacturing method thereof |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20010828 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20071026 Year of fee payment: 6 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20081026 Year of fee payment: 7 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20091026 Year of fee payment: 8 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101026 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20101026 Year of fee payment: 9 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111026 Year of fee payment: 10 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20111026 Year of fee payment: 10 |
|
FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20121026 Year of fee payment: 11 |
|
LAPS | Cancellation because of no payment of annual fees |