JPH0790375A - Production of thick bend steel pipe having high strength and high toughness - Google Patents
Production of thick bend steel pipe having high strength and high toughnessInfo
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- JPH0790375A JPH0790375A JP24144793A JP24144793A JPH0790375A JP H0790375 A JPH0790375 A JP H0790375A JP 24144793 A JP24144793 A JP 24144793A JP 24144793 A JP24144793 A JP 24144793A JP H0790375 A JPH0790375 A JP H0790375A
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Abstract
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 producing a bent steel pipe by hot bending a welded steel pipe, and more particularly to a method for producing a bent steel pipe having a large diameter, high strength, thick wall and high toughness.
【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 Recently, in oil and natural gas line pipes, there is a tendency to increase the transportation pressure in the line pipes in order to improve the transportation efficiency. Higher toughness has come to be required as the operating environment becomes colder.
【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 steel pipes and bent steel pipes are used as line pipes, and bend steel pipes used in river crossing regions are manufactured by bending a straight steel pipe into an appropriate angle. However, for example, in the case of a large-diameter pipe having an outer diameter of 16 inches or more, hot working is often used for working because it is cost-effective to manufacture such a bent steel pipe. Due to the heating, the material properties change, and in particular the deterioration of the toughness of the weld metal poses 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。Naturally, this problem can be avoided by manual welding, small current welding, MIG welding, and multi-layer welding by small heat input submerged arc welding.
For these weldings, large heat input submerged arc welding inner and outer surfaces 1
When compared with pass welding, the manufacturing efficiency is significantly 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。In particular, under the circumstances where the reduction of the manufacturing cost is strongly demanded today, it is necessary to develop a more economical manufacturing method of the bent steel pipe on the premise of the large heat input submerged arc welding inner and outer surface one-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。Even in the conventional case, for example, a heating temperature of 850 to 10
300 ℃ after bending at a holding time of less than 120 seconds at 50 ℃
Japanese Patent Application Laid-Open No. 60-258411 discloses an example of cooling up to 15 to 60 ° C./sec, but a large heat input SAW of 90 KJ / cm or more.
There was no thick-walled product that required (submerged arc welding), so 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。Further, as disclosed in Japanese Patent Application Laid-Open No. 61-266126, there has been proposed an idea of defining from hot rolling conditions to bending after manufacturing a welded pipe and subsequent heat treatment conditions. There was no thick-walled product that required a high heat input SAW of 90 KJ / cm or more, so 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 large heat input submerged arc when producing a straight welded steel pipe in a method for producing a large diameter welded bend steel pipe in which hot bending is performed. It is an object of the present invention to provide a method for manufacturing a thick-walled bent steel pipe which can obtain high strength and high toughness even if the one-pass inner and outer surface welding is performed.
【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 bend a straight welded steel pipe obtained by one-pass inner / outer surface welding by high heat input submerged arc welding 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 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。In order to solve such a problem, the inventors of the present invention have made various studies on the premise that the inner and outer surfaces are made into one pass by the large heat input submerged arc welding and the bending is performed by the hot working. As a result, by comprehensively defining the material composition, rolling conditions, weld metal composition, bending conditions, and post-processing heat treatment conditions, the strength and toughness of thick-wall bend steel pipes that were previously unattainable can be secured. The present invention has been completed by finding that the above can be achieved.
【００１１】ここに、本発明は、重量％で、 Ｃ：0.04〜0.10％、 Si：0.30％以下、 Mn：1.70
％以下、 Ni：0.20〜0.60％、 Ti：0.20％以下、 残部Feおよび不可避的不純物からなり、下式から求めら
れる炭素当量Ceq が、0.35〜0.45wt％である鋼を、1100
℃〜1200℃の温度に加熱してから圧延を開始し、690 ℃
〜800 ℃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、 Ｃ：0.04〜0.08％、 Si：0.25％以下、 Mn：1.70
％以下、 Mo：0.03％以下、 Ti：0.008 ％以下、 Ni：0.6
％以下、 Ｂ：0.003 ％以下、 Ｎ：0.0060％以下、 酸素：0.
04％以下 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高強度、厚肉、高靱性ベンド鋼管
の製造方法である。In the present invention, the weight% is C: 0.04 to 0.10%, Si: 0.30% or less, Mn: 1.70.
% Or less, Ni: 0.20 to 0.60%, Ti: 0.20% or less, the balance Fe and unavoidable impurities, and the carbon equivalent Ceq obtained from the following formula is 0.35 to 0.45wt%.
℃ ~ 1200 ℃, then start rolling, then 690 ℃
After rolling at a temperature of ~ 800 ℃, allow to cool or
After completion of rolling, the product was obtained by forcibly cooling from the rolling end temperature to 450 ° C or less at a cooling rate of 5 to 50 ° C / sec and then forcibly cooling to room temperature or allowing it to cool to room temperature. Weld metal, made of steel plate, in weight%, C: 0.04 to 0.08%, Si: 0.25% or less, Mn: 1.70
% Or less, Mo: 0.03% or less, Ti: 0.008% or less, Ni: 0.6
% Or less, B: 0.003% or less, N: 0.0060% or less, oxygen: 0.
04% or less The remainder is produced by manufacturing a straight welded steel pipe in which the mixed components and Fe composition that inevitably enter during welding are produced, and the planned bend portion of the steel pipe is heated to a temperature of 980 ° C to 1050 ° C. Immediately after finishing the bending process, the temperature in the 1/2 plate thickness part of the product is cooled between 800 ℃ ~ 500 ℃ at an average cooling rate of 8 ℃ / sec or more and quenched, then 500 ℃ ~ 600 ℃. It is a method for producing a high-strength, thick-walled, high-toughness bend steel pipe characterized by tempering at a temperature.
【００１２】 Ceq＝Ｃ＋１／６(Mn)＋１／15 (Cu＋Ni) ＋１／５ (Cr＋Mo＋Ｖ) ・・(1) Ceq = C + 1/6 (Mn) +1/15 (Cu + Ni) +1/5 (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 are limited as described above in the present invention will be explained 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 ensuring strength.
If it is less than 0.04%, the required strength cannot be obtained, while if it exceeds 0.10%, the welded portion is hardened and the toughness deteriorates.
【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 required as a deoxidizing agent during steel making, but if it exceeds 0.30%, the toughness of the weld heat affected zone (HAZ) will be reduced, so it should be 0.30% or less. .
【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 necessary as a deoxidizing agent and for improving strength and toughness, but if it exceeds 1.70%, the welded portion is hardened and the toughness deteriorates.
【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 for improving the toughness, but if it is less than 0.20%, it is not very effective, while if it exceeds 0.60%, the toughness does not change so much and it is disadvantageous in cost. In the present invention, it 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 the toughness due to the effect of refining the austenite grains, excessive addition and excessive dilution into the weld metal are uneconomical and may cause deterioration of 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。Carbon equivalent (Ceq) is defined by considering the balance between strength and toughness, but Ceq: 0.35
If less than%, the target strength cannot be achieved, while 0.45%
%, The toughness will be insufficient, so 0.35 to 0.45% is set.
【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 hot-rolled. Hot rolling conditions Heated prior to hot rolling, the heating temperature at that time is set to 1100 ° C or higher in order to obtain a 100% austenite structure and to secure strength, but when it exceeds 1200 ° C 1100 ° C-
It was set to 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 rolling end temperature exceeds 800 ° C., the micronization of the structure is insufficient and the toughness deteriorates. On the contrary, if the temperature is less than 690 ° C., ferrite is processed, and the toughness deteriorates. The end 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 hot rolling is finished, it is cooled. According to the present invention, there are the following three modes, and the desired toughness,
The strength may be determined as appropriate. (1) Allow to cool to room temperature. (2) Forcedly cool to 450 ° C or less at a cooling rate of 5 to 50 ° C / sec, and then allow to cool to room temperature. (3) Forced cooling 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 results and the toughness deteriorates. It should be noted that the improvement in strength and the improvement in toughness are not compatible with each other, and although the above (1) is a means for improving toughness, the decrease in strength is inevitable. Further, although the means of the above (3) is advantageous in achieving high strength, 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, the plate thickness is usually 1 to 2 inches, and a welded steel pipe after bending is produced from this hot rolled steel plate. In the present invention, such bending and welding is performed. The operation itself is not particularly limited, and a conventional one may be used, but it is preferably performed by one-pass inner and outer surface welding by high heat input submerged arc welding 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 welded portion thus obtained by high heat input welding, that is, the weld metal composition 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 welded portion is hardened and the toughness deteriorates. Si (silicon): Silicon, if over 0.25%, lowers the toughness of the welded portion, so it should be 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): When manganese exceeds 1.70%, the weld zone is hardened and the toughness deteriorates. Mo (molybdenum): It is desirable not to contain Mo as it causes deterioration of toughness, but 0.03% is acceptable, so 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%, the effect is not significant and the cost is high, which is not a good idea. Ti (titanium): Titanium has the effect of improving the toughness by the effect of refining the austenite grains, but if it is too much, it may lead to deterioration of the toughness of the weld metal, 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): Boron is 0.003% or less in order to improve toughness due to the effect of refining austenite grains. N (nitrogen): Decrease in toughness, so 0.0060% or less. Oxygen: Oxygen causes deterioration of toughness, so 0.04% or less is used.
【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 obtaining a straight welded steel pipe in this manner, hot bending is applied to obtain a bend steel pipe. Hot Bending When the entire large diameter steel pipe targeted by the present invention is exposed to high temperature for a long time, the softened steel pipe deforms due to its own weight. Therefore, in the present invention, even when bending, induction heating that can perform heating in a short time and can perform local heating is adopted.
【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 secure the strength of the base metal.
The temperature was set to 0 ° C or higher, and was set to 1050 ° C or lower to prevent deterioration of toughness. (ii) Cooling rate during quenching The heated portion is cooled immediately after bending, but in order to secure toughness, when cooling in the temperature range of 800 to 500 ° C, 8 ° C /
Average cooling rate of sec or more is required. Preferably 8
Cool at an average cooling rate of ~ 15 ° C / sec. The temperature shall be that of the half plate thickness of the product. (iii) Tempering 600 ° C or less to prevent strength reduction, 500 to secure toughness
Tempering is performed at a temperature of ℃ or more. Next, the working effects of the present invention will be described more specifically by way of 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。[Examples] Steel materials having the steel compositions shown in Table 1 were hot-rolled, and after cooling, one layer each of the inner and outer surfaces was welded by submerged arc welding with a large heat input of 90 KJ / cm on at least one of the inner and outer surfaces. After welding, hot bending was performed at 90 °, and then heat treatment such as quenching and tempering was performed. The respective processing and processing conditions are also summarized in Table 1. 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２】 [Table 2]
【００３４】[0034]
【発明の効果】以上の説明から明らかなように、本発明
の製造方法によれば、直状鋼管の製造工程において、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
なった後、熱間加工を行なっても、加工部全体に高強
度、高靱性が付与され、これにより製造コストを低減し
た、かつ製品価値の高い厚肉のベンド鋼管が製造でき
る。As is apparent from the above description, according to the manufacturing method of the present invention, in the manufacturing process of the straight steel pipe, after the single layer welding for each of the inner and outer surfaces is performed by the submerged arc welding with a large heat input. Even if hot working is performed, high strength and high toughness are imparted to the entire worked part, which makes it possible to manufacture a thick-walled bent steel pipe with reduced manufacturing cost and high product value.
───────────────────────────────────────────────────── 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 Ｃ２２Ｃ 38/00 ３０１ Ｚ 38/14 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location C22C 38/00 301 Z 38/14
Claims (1)
％以下、 Ni：0.20〜0.60％、 Ti：0.20％以下、 残部Feおよび不可避的不純物からなり、下式から求めら
れる炭素当量Ceq が、0.35〜0.45wt％である鋼を、1100
℃〜1200℃の温度に加熱してから圧延を開始し、690 ℃
〜800 ℃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、 Ｃ：0.04〜0.08％、 Si：0.25％以下、 Mn：1.70
％以下、 Mo：0.03％以下、 Ti：0.008 ％以下、 Ni：0.6
％以下、 Ｂ：0.003 ％以下、 Ｎ：0.0060％以下、 酸素：0.
04％以下 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高強度、厚肉、高靱性ベンド鋼管
の製造方法。 Ceq＝Ｃ＋１／６(Mn)＋１/15 ( Cu＋Ni) ＋１／５ (Cr
＋Mo＋Ｖ)1. By weight%, C: 0.04 to 0.10%, Si: 0.30% or less, Mn: 1.70
% Or less, Ni: 0.20 to 0.60%, Ti: 0.20% or less, the balance Fe and unavoidable impurities, and the carbon equivalent Ceq obtained from the following formula is 0.35 to 0.45wt%.
℃ ~ 1200 ℃, then start rolling, then 690 ℃
After rolling at a temperature of ~ 800 ℃, allow to cool or
After completion of rolling, the product was obtained by forcibly cooling from the rolling end temperature to 450 ° C or less at a cooling rate of 5 to 50 ° C / sec and then forcibly cooling to room temperature or allowing it to cool to room temperature. Weld metal, made of steel plate, in weight%, C: 0.04 to 0.08%, Si: 0.25% or less, Mn: 1.70
% Or less, Mo: 0.03% or less, Ti: 0.008% or less, Ni: 0.6
% Or less, B: 0.003% or less, N: 0.0060% or less, oxygen: 0.
04% or less The remainder is produced by manufacturing a straight welded steel pipe in which the mixed components and Fe composition that inevitably enter during welding are produced, and the planned bend portion of the steel pipe is heated to a temperature of 980 ° C to 1050 ° C. Immediately after finishing the bending process, the temperature in the 1/2 plate thickness part of the product is cooled between 800 ℃ ~ 500 ℃ at an average cooling rate of 8 ℃ / sec or more and quenched, then 500 ℃ ~ 600 ℃ A method for producing a high-strength, thick-walled, high-toughness bend steel pipe characterized by tempering at a temperature. Ceq = C + 1/6 (Mn) +1/15 (Cu + Ni) +1/5 (Cr
+ Mo + V)
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 true JPH0790375A (en) | 1995-04-04 |
| JP2827839B2 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) |
Cited By (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 |
| ITTO20110139A1 (en) * | 2011-02-18 | 2012-08-19 | 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 |
| EP3636787A4 (en) * | 2017-05-22 | 2020-09-30 | Nippon Steel Corporation | Bent steel pipe and method for producing same |
Citations (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
Patent Citations (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 |
Cited By (9)
| 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 |
| EP2045348A1 (en) * | 2006-07-13 | 2009-04-08 | Sumitomo Metal Industries Limited | Bend pipe and process for producing the same |
| EP2045348A4 (en) * | 2006-07-13 | 2011-05-11 | Sumitomo Metal Ind | Bend pipe and process for producing the same |
| NO341657B1 (en) * | 2006-07-13 | 2017-12-18 | Sumitomo Metal Ind | Method of making hot bending tubes |
| WO2008139639A1 (en) * | 2007-05-16 | 2008-11-20 | Sumitomo Metal Industries, Ltd. | Bend pipe and process for manufacturing the same |
| JPWO2008139639A1 (en) * | 2007-05-16 | 2010-07-29 | 住友金属工業株式会社 | Bend pipe and manufacturing method thereof |
| ITTO20110139A1 (en) * | 2011-02-18 | 2012-08-19 | 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 |
| WO2012110627A1 (en) | 2011-02-18 | 2012-08-23 | Sistemi Sospensioni S.P.A. | Method for manufacturing high-strength steel sheet parts subject in use to fatigue stresses |
| EP3636787A4 (en) * | 2017-05-22 | 2020-09-30 | Nippon Steel Corporation | Bent steel pipe and method for producing same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2827839B2 (en) | 1998-11-25 |
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