JP2827839B2 - Method of manufacturing high strength, thick wall, high toughness bend steel pipe - Google Patents
Method of manufacturing high strength, thick wall, high toughness bend steel pipeInfo
- Publication number
- JP2827839B2 JP2827839B2 JP5241447A JP24144793A JP2827839B2 JP 2827839 B2 JP2827839 B2 JP 2827839B2 JP 5241447 A JP5241447 A JP 5241447A JP 24144793 A JP24144793 A JP 24144793A JP 2827839 B2 JP2827839 B2 JP 2827839B2
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- temperature
- steel pipe
- steel
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、溶接鋼管に熱間で曲げ
加工を施してベンド鋼管を製造する方法、特に、大径で
高強度、厚肉、高靱性のベンド鋼管の製造方法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a bent steel pipe by hot bending a welded steel pipe, and more particularly, to a method for manufacturing a large-diameter, high-strength, thick-wall, high-toughness bent steel pipe.
【０００２】[0002]
【従来の技術】最近、石油、天然ガスラインパイプにお
いて、輸送効率を上げるために、ラインパイプの管内の
輸送圧力を増加させる傾向にあり、これにともないライ
ンパイプ素材の高強度、厚肉化さらに使用環境の寒冷地
化にともなう高靱性化が要求されるようになってきてい
る。2. Description of the Related Art In recent years, in order to improve the transportation efficiency of oil and natural gas line pipes, there has been a tendency to increase the transportation pressure in the line pipes. Higher toughness has been required with the use of the environment in colder climates.
【０００３】ところで、ラインパイプには、直状鋼管と
ベンド鋼管の２種が用いられ、河川横断地域で用いられ
るベンド鋼管は直状鋼管を適宜角度に曲げ加工して製造
する。しかし、例えば外径が１６インチ以上という大径
管の場合、このようなベンド鋼管を製造するには、コス
ト面で有利なため、加工には熱間加工がよく用いられる
が、熱間加工時、加熱のため、材料特性が変化し、特に
溶接金属の靱性の低下が問題となる。By the way, two types of straight pipes and bent steel pipes are used for line pipes. Bend steel pipes used in river crossing areas are manufactured by bending straight steel pipes at appropriate angles. However, in the case of a large-diameter pipe having an outer diameter of, for example, 16 inches or more, hot working is often used for manufacturing such a bent steel pipe because it is advantageous in terms of cost. Due to the heating, the material properties change, and in particular, a decrease in the toughness of the weld metal becomes a problem.
【０００４】この問題に対し、当然のことながら、手溶
接や、小電流溶接、MIG 溶接や小入熱サブマージアーク
溶接による多層溶接によって回避することはできるが、
これらの溶接では大入熱サブマージアーク溶接内外面１
パス溶接と比較した場合、大幅に製造能率が低下する。[0004] Naturally, this problem can be avoided by multi-layer welding by manual welding, small current welding, MIG welding or small heat input submerged arc welding.
In these weldings, large heat input submerged arc welding inner and outer surfaces 1
When compared with pass welding, manufacturing efficiency is greatly reduced.
【０００５】特に、今日のように製造コストの低減が強
く求められる状況下では大入熱サブマージアーク溶接内
外面１パス溶接を前提としたベンド鋼管のより経済的な
製造方法を開発しなければならない。[0005] In particular, in a situation where a reduction in manufacturing cost is strongly demanded as in today, a more economical method of manufacturing a bend steel pipe must be developed on the premise of high heat input submerged arc welding inner and outer surface single-pass welding. .
【０００６】従来にあっても、例えば加熱温度 850〜10
50℃で 120秒以内の保持時間で曲げ加工してから300 ℃
まで15〜60℃/secで冷却する例が特開昭60−258411号公
報に開示されているが、90KJ/cm 以上の大入熱ＳＡＷ
(サブマージアーク溶接) を必要とする厚肉品はなく十
分とは云えなかった。[0006] Even in the past, for example, a heating temperature of 850-10
300 ° C after bending at 50 ° C with holding time within 120 seconds
Japanese Patent Application Laid-Open No. 60-258411 discloses an example of cooling at a temperature of 15 to 60 ° C./sec.
There was no thick-walled product that required (submerged arc welding) and it was not sufficient.
【０００７】また、特開昭61−266126号公報に開示され
ているように、熱間圧延条件から溶接管製造後の曲げ加
工、そしてその後の熱処理条件まで規定する考えも提案
されているが、90KJ/cm 以上の大入熱ＳＡＷを必要とす
る厚肉品はなく、十分とは云えなかった。[0007] As disclosed in Japanese Patent Application Laid-Open No. 61-266126, there has been proposed an idea of defining conditions from hot rolling to bending after the production of a welded pipe and subsequent heat treatment. There was no thick product that required a large heat input SAW of 90 KJ / cm or more, and it was not sufficient.
【０００８】[0008]
【発明が解決しようとする課題】ここに、本発明の目的
は、熱間で曲げ加工を行なう大径溶接ベンド鋼管の製造
方法において、直状溶接鋼管の製造の際に、大入熱サブ
マージアーク溶接による内外面１パス溶接を行なって
も、なお、高強度、高靱性の得られる厚肉ベンド鋼管の
製造方法を提供することである。SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a large-diameter welded bent steel pipe which is hot-bending, and which has a large heat input submerged arc when manufacturing a straight welded steel pipe. An object of the present invention is to provide a method for producing a thick-walled bent steel pipe which can obtain high strength and high toughness even when one-pass welding is performed on the inner and outer surfaces by welding.
【０００９】本発明の具体的目的は、90KJ/cm 以上の大
入熱サブマージアーク溶接による内外面１パス溶接によ
り得た直状溶接鋼管を曲げ加工して強度530N/mm2以上、
靱性vE-30 ≧100(J)以上の母材金属と、強度530N/mm2以
上、靱性vE-30 ≧100(J)以上の溶接金属を備えた厚肉ベ
ンド鋼管の製造方法を提供することである。A specific object of the present invention is to straighten a straight welded steel pipe obtained by single-pass welding on the inner and outer surfaces by submerged arc welding with a large heat input of 90 KJ / cm or more to obtain a strength of 530 N / mm 2 or more.
Providing and toughness vE -30 ≧ 100 (J) or more of the base metal, the strength 530n / mm 2 or more, a manufacturing method of the thick bend steel with the toughness vE -30 ≧ 100 (J) or more weld metal It is.
【００１０】[0010]
【課題を解決するための手段】本発明者らは、かかる課
題を解決すべく、大入熱サブマージアーク溶接による内
外面１パス化、および熱間加工によるベンド加工を前提
として種々検討を重ねた結果、素材組成、圧延条件、溶
接金属組成、曲げ加工条件、および加工後の熱処理条件
までを、総括的に規定することによって、従来得られな
かった程度の厚肉ベンド鋼管の強度、靱性の確保を図る
ことができることを見出し、本発明を完成した。Means for Solving the Problems In order to solve such problems, the present inventors have conducted various studies on the premise that the inner and outer surfaces are made one pass by large heat input submerged arc welding and that bend processing is performed by hot working. By comprehensively defining the results, material composition, rolling conditions, weld metal composition, bending processing conditions, and post-processing heat treatment conditions, the strength and toughness of thick bend steel pipes that were not obtained before can be secured. It has been found that the present invention can be achieved, and the present invention has been completed.
【００１１】ここに、本発明は、重量％で、 を含み、下式から求められる炭素当量Ｃｅｑが、０．３
５〜０．４５ｗｔ％である鋼を、１１００℃〜１２００
℃の温度に加熱してから圧延を開始し、６９０℃〜８０
０℃の温度で圧延を完了後、放冷するか、または、圧延
終了後、圧延終了温度から４５０℃以下まで冷却速度５
〜５０℃／ｓｅｃで強制冷却してからそのまゝ室温にま
で強制冷却するかもしくは放冷して室温にまで冷却し、
得られた鋼板を素材として、溶接金属が、重量％で、 残部は溶接上不可避的に入ってくる混入成分およびＦｅ
の組成になる、直状溶接鋼管を製造し、当該鋼管のベン
ド予定部を９８０℃〜１０５０℃の温度に加熱している
うちに曲げ加工を終え、直ちに製品の１／２板厚部にお
ける温度が、８００℃〜５００℃の間を８℃／ｓｅｃ以
上の平均冷却速度で冷却して焼入れした後、５００℃〜
６００℃の温度で焼き戻すことを特徴とする溶接入熱量
９０ＫＪ／ｃｍ以上で板厚４０ｍｍ（１．５８インチ）
の溶接が可能となる高強度、厚肉、高靱性ベンド鋼管の
製造方法である。[0011] Here, the present invention provides, And the carbon equivalent Ceq determined from the following equation is 0.3
5% to 0.45% by weight of steel at 1100 ° C. to 1200
Rolling is started after heating to a temperature of 690 ° C to 80 ° C.
After the completion of the rolling at a temperature of 0 ° C., the steel is allowed to cool, or after the completion of the rolling, the cooling rate is reduced from the rolling end temperature to 450 ° C. or less.
Forcibly cooling at ~ 50 ° C / sec and then forcibly cooling to room temperature or leaving to cool to room temperature,
Using the obtained steel sheet as a material, the weld metal is The balance consists of mixed components and Fe
A straight welded steel pipe having the following composition is manufactured, and the bending process is completed while the bend scheduled portion of the steel pipe is heated to a temperature of 980 ° C to 1050 ° C. However, after cooling between 800 ° C and 500 ° C at an average cooling rate of 8 ° C / sec or more and quenching,
Welding heat input characterized by tempering at a temperature of 600 ° C
Over 90KJ / cm and 40mm (1.58 inch) thickness
This is a method for producing a high-strength, thick-wall, high-toughness bend steel pipe that enables welding of steel.
【００１２】 Ceq＝Ｃ＋１／６(Mn)＋１／15 (Cu＋Ni) ＋１／５ (Cr＋Mo＋Ｖ) ・・(1) Ceq = C + ／ (Mn) +1/15 (Cu + Ni) + ／ (Cr + Mo + V) (1)
【００１３】[0013]
【作用】次に、本発明において鋼組成、溶金組成、圧延
加工条件さらに熱処理条件を上述のように限定した理由
を、その作用とともに説明する。なお、本明細書におい
て特にことわりがない限り、「％」は「重量％」であ
る。Next, the reason why the steel composition, the molten metal composition, the rolling conditions, and the heat treatment conditions in the present invention are limited as described above will be described together with the function thereof. In this specification, “%” is “% by weight” unless otherwise specified.
【００１４】素材組成 Ｃ (炭素):炭素は、強度を確保するために必要な元素で
0.04％未満では、必要な強度が得られず、一方0.10％を
超えると、溶接部が硬化し、靱性が劣化する。 Material composition C (carbon): Carbon is an element necessary for securing strength.
If it is less than 0.04%, the required strength cannot be obtained, while if it exceeds 0.10%, the weld is hardened and the toughness is deteriorated.
【００１５】Si (珪素) ：珪素は、製鋼時、脱酸剤とし
て必要な元素であるが、0.30％を超えると、溶接熱影響
部 (HAZ)の靱性を低下させるので、0.30％以下とする。Si (silicon): Silicon is an element necessary as a deoxidizing agent in steel making, but if it exceeds 0.30%, the toughness of the weld heat affected zone (HAZ) is reduced. .
【００１６】Mn (マンガン）：マンガンは、脱酸剤とし
てまた強度、靱性向上のため、必要であるが、1.70％を
超えると、溶接部が硬化し、靱性が劣化する。Mn (manganese): Manganese is required as a deoxidizing agent and for improving strength and toughness. However, if it exceeds 1.70%, the weld is hardened and the toughness is deteriorated.
【００１７】Ni (ニッケル) ：ニッケルは靱性を向上さ
せるのに有効であるが、0.20％未満ではあまり効果がな
く、一方0.60％超としてもあまり靱性は変わらず、かつ
コスト的に不利なため、本発明では0.20〜0.60％とす
る。Ni (nickel): Nickel is effective in improving toughness, but less than 0.20% has little effect, while exceeding 0.60% does not change much toughness and is disadvantageous in cost. In the present invention, the content is 0.20 to 0.60%.
【００１８】Ti (チタン) ：チタンはＢの有効活用と、
オ−ステナイト粒の微細化効果による靱性向上のために
必要であるが、過剰添加および溶接金属への過剰希釈
は、不経済であり、また、溶接金属の靱性の劣化を招く
おそれが有るため、0.20％以下とする。Ti (titanium): Titanium is an effective use of B,
Although necessary for improving toughness due to the austenite grain refinement effect, excessive addition and excessive dilution to the weld metal are uneconomical and may cause deterioration in the toughness of the weld metal. 0.20% or less.
【００１９】炭素当量(Ceq) 強度と靱性とのバランスを考えて規定するが、Ceq:0.35
％未満では目標強度を達成できなくなり、一方、0.45％
をこえると、靱性が不足するので、0.35〜0.45％とす
る。The carbon equivalent (Ceq) is defined in consideration of the balance between strength and toughness.
%, The target intensity cannot be achieved, while 0.45%
If the ratio exceeds the range, the toughness is insufficient.
【００２０】次に、かかる鋼組成を有する鋼材に、熱間
圧延を行う。熱間圧延条件 熱間圧延に先立って加熱されるが、そのときの加熱温度
は、100 ％オ−ステナイト組織とするためおよび強度確
保のため1100℃以上とするが、1200℃を超えるとオ−ス
テナイト粒が過大になり、靱性低下を招くので1100℃〜
1200℃とした。Next, the steel material having such a steel composition is subjected to hot rolling. Hot rolling conditions Heating is performed prior to hot rolling. The heating temperature at that time is set to 1100 ° C or more in order to obtain a 100% austenite structure and to secure strength. 1100 ° C ~
It was 1200 ° C.
【００２１】圧延終了温度が800 ℃を超えると、組織の
微細化が不十分で靱性劣化を招き、逆に690 ℃未満で
は、フェライトに加工を加えることになり、靱性劣化を
招くので 熱間圧延終了温度は、690 ℃〜 800℃とし
た。If the temperature at the end of rolling exceeds 800 ° C., the microstructure is insufficiently refined to cause toughness degradation. If the temperature is less than 690 ° C., the ferrite must be worked and the toughness is deteriorated. The termination temperature was 690 ° C to 800 ° C.
【００２２】熱間圧延終了後、冷却するが、その態様に
は本発明によれば、次の三つがあり、目的とする靱性、
強度を適宜考慮して決定すればよい。 (1) そのまま室温まで放冷する。 (2) 450 ℃以下まで５〜50℃/secの冷却速度で、強制冷
却した後、常温まで放冷する。 (3) 常温まで、５〜50℃/secの冷却速度で、強制冷却す
る。After the completion of hot rolling, cooling is performed. According to the present invention, there are the following three modes.
What is necessary is just to determine in consideration of intensity | strength suitably. (1) Allow to cool to room temperature. (2) After forcibly cooling to 450 ° C or less at a cooling rate of 5 to 50 ° C / sec, cool to room temperature. (3) Forcibly cool to room temperature at a cooling rate of 5 to 50 ° C / sec.
【００２３】強制冷却する場合、冷却速度が５℃/sec未
満では、強度上昇の効果なく、一方、50℃/secを超える
と、焼入れ組織になり靱性が劣化する。なお、強度改善
と靱性改善とは両立せず、上記(1) は靱性を改善する手
段であるが、強度の低下は免れない。また上記(3) の手
段は高強度とするのに有利であるが、靱性の改善は期待
できない。上記(2) はそれらの中間的手段ということが
できる。In the case of forced cooling, if the cooling rate is less than 5 ° C./sec, there is no effect of increasing the strength, while if it exceeds 50 ° C./sec, a quenched structure is formed and the toughness is deteriorated. In addition, improvement in strength and improvement in toughness are not compatible, and the above (1) is a means for improving toughness, but a decrease in strength is inevitable. The means (3) is advantageous for increasing the strength, but improvement in toughness cannot be expected. The above (2) can be said to be an intermediate means between them.
【００２４】このようにして得られる熱間圧延鋼板は、
それに制限されるものではないが、通常板厚が１〜２イ
ンチのものであり、次いでこの熱間圧延鋼板から曲げ加
工後溶接鋼管を製造するが、本発明においてはそのよう
な曲げ加工および溶接操作自体は特に制限はなく、慣用
のそれを用いればよいが、好ましくは90KJ/cm 以上の大
入熱サブマージアーク溶接による内外面１パス溶接によ
り行う。The hot-rolled steel sheet thus obtained is
Although not limited thereto, usually, the thickness is 1 to 2 inches, and then a welded steel pipe is manufactured from this hot-rolled steel sheet after bending, and in the present invention, such bending and welding are performed. The operation itself is not particularly limited, and a conventional one may be used. Preferably, the operation is performed by one-pass welding of the inner and outer surfaces by submerged arc welding with a large heat input of 90 KJ / cm or more.
【００２５】このように高入熱溶接により得られる溶接
部の金属組成、つまり溶接金属組成は次のように規定す
る。溶接金属組成 Ｃ (炭素):炭素は、強度を確保するために必要な元素で
0.04％未満では、必要な強度が得られず、一方0.08％を
超えると、溶接部が硬化し、靱性が劣化する。 Si (珪素) ：珪素は、0.25％を超えると、溶接部の靱性
を低下させるので、0.25％以下とする。The metal composition of the weld obtained by the high heat input welding, that is, the composition of the weld metal is defined as follows. Weld metal composition C (carbon): Carbon is an element necessary to secure strength.
If it is less than 0.04%, the required strength cannot be obtained, while if it exceeds 0.08%, the weld is hardened and the toughness is deteriorated. Si (silicon): If silicon exceeds 0.25%, the toughness of the welded portion is reduced, so that the content of silicon is set to 0.25% or less.
【００２６】Mn (マンガン）：マンガンは、1.70％を超
えると、溶接部が硬化し、靱性が劣化する。 Mo (モリブデン) ：靱性低下を招くので含有しない方が
望ましいが、0.03％までは許容できるので、0.03％以下
とする。Mn (manganese): If the manganese content exceeds 1.70%, the weld is hardened and the toughness is deteriorated. Mo (Molybdenum): It is desirable not to contain Mo because it causes a decrease in toughness, but up to 0.03% is acceptable, so it is set to 0.03% or less.
【００２７】Ni (ニッケル) ：ニッケルは、0.6 ％超で
は、著しい効果はなくコスト高になり得策ではない。 Ti (チタン) ：チタンはオ−ステナイト粒の微細化効果
による靱性向上の効果があるが、余り多いと溶接金属の
靱性の劣化を招くおそれが有るため、0.008 ％以下とす
る。Ni (nickel): If the content of nickel exceeds 0.6%, there is no remarkable effect and the cost is high, which is not a good idea. Ti (titanium): Titanium has the effect of improving toughness due to the effect of refining austenite grains, but if it is too much, the toughness of the weld metal may be degraded, so it is made 0.008% or less.
【００２８】Ｂ（ボロン）：ボロンは、オ−ステナイト
粒の微細化効果による靱性向上のため0.003 ％以下とす
る。 Ｎ (窒素) ：靱性低下を招くので0.0060％以下とする。 酸素：酸素は靱性低下を招くので0.04％以下とする。B (boron): The content of boron is 0.003% or less for improving toughness due to the effect of refining austenite grains. N (nitrogen): The content is set to 0.0060% or less because toughness is reduced. Oxygen: Oxygen causes a decrease in toughness, so it is made 0.04% or less.
【００２９】このようにして直状の溶接鋼管を得てか
ら、熱間での曲げ加工を加えてベンド鋼管とする。熱間曲げ加工 本発明が対象とするような大径鋼管全体を長時間、高温
にさらすと軟化した鋼管が自重により変形をおこす。そ
のため、本発明にあっては曲げ加工に際しても、短時間
で加熱可能な、かつ局部加熱が可能な誘導加熱を採用す
る。After a straight welded steel pipe is obtained in this way, a bent pipe is formed by hot bending. Hot Bending When the entire large-diameter steel pipe as the object of the present invention is exposed to high temperature for a long time, the softened steel pipe is deformed by its own weight. For this reason, in the present invention, induction heating that can be heated in a short time and can be locally heated is also employed in bending.
【００３０】(i) 加熱温度... 母材強度確保のため、98
0 ℃以上とし、靱性劣化を防ぐ理由から1050℃以下とし
た。 (ii)焼入れ時、冷却速度 曲げ加工後直ちに、加熱部分を冷却するが、靱性確保の
ためには、800 〜500℃の温度領域を冷却するとき８℃/
sec以上の平均冷却速度が必要である。好ましくは、８
〜15℃/secの平均冷却速度で冷却する。なお、温度は製
品の１／２板厚部のそれとする。 (iii) 焼戻し 強度低下防止のために 600℃以下、靱性確保のため500
℃以上の温度で焼戻し処理を行う。次に、実施例によっ
て本発明の作用効果をさらに具体的に説明する。(I) Heating temperature: 98 to ensure base metal strength
The temperature was set to 0 ° C. or higher, and was set to 1050 ° C. or lower for the purpose of preventing toughness deterioration. (ii) Cooling speed during quenching Immediately after bending, the heated part is cooled. However, in order to ensure toughness, 8 ° C /
An average cooling rate of more than sec is required. Preferably, 8
Cool at an average cooling rate of ~ 15 ° C / sec. Note that the temperature is that of a half-plate thickness part of the product. (iii) Tempering: 600 ° C or less to prevent reduction in strength, 500 to ensure toughness
Perform tempering at a temperature of at least ℃. Next, the operation and effect of the present invention will be described more specifically with reference to examples.
【００３１】[0031]
【実施例】表１に示す鋼組成を有する鋼材を熱間圧延
し、冷却後、内、外面の少なくとも一方が90KJ/cm の大
入熱のサブマージアーク溶接で、内外面各１層溶接を行
い、溶接後、熱間で90°の曲げ加工を行ってから、焼入
れ、焼戻しの熱処理を行った。各加工および処理条件は
同じく表１にまとめて示す。表２は溶接金属の鋼組成の
分析値とその機械的特性を示すものである。EXAMPLE A steel material having the steel composition shown in Table 1 was hot-rolled, cooled, and then, at least one of the inner and outer surfaces was subjected to submerged arc welding with a large heat input of 90 KJ / cm to perform one-layer welding on each of the inner and outer surfaces. After the welding, a 90 ° bending process was performed, and then a quenching and tempering heat treatment was performed. Table 1 also shows the respective processing and processing conditions. Table 2 shows the analytical values of the steel composition of the weld metal and its mechanical properties.
【００３２】[0032]
【表１】 [Table 1]
【００３３】[0033]
【表１】 [Table 1]
【００３４】[0034]
【表２】 [Table 2]
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｃ２２Ｃ 38/00 ３０１ Ｃ２２Ｃ 38/00 ３０１Ｚ 38/58 38/58 (58)調査した分野(Int.Cl.6，ＤＢ名) C21D 8/10 C21D 9/08 C21D 9/50 101 B23K 31/00 B23K 35/30 340 C22C 38/00 - 38/60──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. 6 identification code FI C22C 38/00 301 C22C 38/00 301Z 38/58 38/58 (58) Fields investigated (Int.Cl. 6 , DB name) C21D 8/10 C21D 9/08 C21D 9/50 101 B23K 31/00 B23K 35/30 340 C22C 38/00-38/60
Claims (1)
５〜０．４５ｗｔ％である鋼を、１１００℃〜１２００
℃の温度に加熱してから圧延を開始し、６９０℃〜８０
０℃の温度で圧延を完了後、放冷するか、または、圧延
終了後、圧延終了温度から４５０℃以下まで冷却速度５
〜５０℃／ｓｅｃで強制冷却してからそのまゝ室温にま
で強制冷却するかもしくは放冷して室温にまで冷却し、
得られた鋼板を素材として、溶接金属が、重量％で、 残部は溶接上不可避的に入ってくる混入成分およびＦｅ
の組成になる、直状溶接鋼管を製造し、当該鋼管のベン
ド予定部を９８０℃〜１０５０℃の温度に加熱している
うちに曲げ加工を終え、直ちに製品の１／２板厚部にお
ける温度が、８００℃〜５００℃の間を８℃／ｓｅｃ以
上の平均冷却速度で冷却して焼入れした後、５００℃〜
６００℃の温度で焼き戻すことを特徴とする溶接入熱量
９０ＫＪ／ｃｍ以上で板厚４０ｍｍ（１．５８インチ）
の溶接が可能となる高強度、厚肉、高靱性ベンド鋼管の
製造方法。 1. In% by weight, And the carbon equivalent Ceq determined from the following equation is 0.3
5% to 0.45% by weight of steel at 1100 ° C. to 1200
Rolling is started after heating to a temperature of 690 ° C to 80 ° C.
After the completion of the rolling at a temperature of 0 ° C., the steel is allowed to cool, or after the completion of the rolling, the cooling rate is reduced from the rolling end temperature to 450 ° C. or less.
Forcibly cooling at ~ 50 ° C / sec and then forcibly cooling to room temperature or leaving to cool to room temperature,
Using the obtained steel sheet as a material, the weld metal is The balance consists of mixed components and Fe
A straight welded steel pipe having the composition of However, after cooling between 800 ° C and 500 ° C at an average cooling rate of 8 ° C / sec or more and quenching,
Tempering at a temperature of 600 ° C., characterized by a welding heat input of 90 KJ / cm or more and a plate thickness of 40 mm (1.58 inch)
Of high-strength, thick-wall, high-toughness bend steel pipe that enables welding of steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5241447A JP2827839B2 (en) | 1993-09-28 | 1993-09-28 | Method of manufacturing high strength, thick wall, high toughness bend steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5241447A JP2827839B2 (en) | 1993-09-28 | 1993-09-28 | Method of manufacturing high strength, thick wall, high toughness bend steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0790375A JPH0790375A (en) | 1995-04-04 |
| JP2827839B2 true JP2827839B2 (en) | 1998-11-25 |
Family
ID=17074447
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5241447A Expired - Lifetime JP2827839B2 (en) | 1993-09-28 | 1993-09-28 | Method of manufacturing high strength, thick wall, high toughness bend steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2827839B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008007737A1 (en) | 2006-07-13 | 2008-01-17 | Sumitomo Metal Industries, Ltd. | Bend pipe and process for producing the same |
| WO2008139639A1 (en) * | 2007-05-16 | 2008-11-20 | Sumitomo Metal Industries, Ltd. | Bend pipe and process for manufacturing the same |
| IT1404267B1 (en) | 2011-02-18 | 2013-11-15 | Sistemi Sospensioni Spa | PROCEDURE FOR THE MANUFACTURE OF COMPONENTS IN SHEET STEEL SHEET BASED ON USE IN FATIGUE, IN PARTICULAR COMPONENTS FOR SUSPENSION OF VEHICLE |
| WO2018216638A1 (en) * | 2017-05-22 | 2018-11-29 | 新日鐵住金株式会社 | Bent steel pipe and method for producing same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61127849A (en) * | 1984-11-26 | 1986-06-16 | Kawasaki Steel Corp | Steel for pipe for working to bent pipe |
| JPS61266126A (en) * | 1985-05-22 | 1986-11-25 | Sumitomo Metal Ind Ltd | Production of high-strength high-toughness bent steel pipe |
| JPS6210212A (en) * | 1985-07-08 | 1987-01-19 | Nippon Kokan Kk <Nkk> | Production of bend pipe |
| JPS62151545A (en) * | 1985-12-25 | 1987-07-06 | Kawasaki Steel Corp | Thick-walled, high-strength, low-pcm bended steel pipe and its production |
-
1993
- 1993-09-28 JP JP5241447A patent/JP2827839B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0790375A (en) | 1995-04-04 |
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