JPS61266126A - Production of high-strength high-toughness bent steel pipe - Google Patents
Production of high-strength high-toughness bent steel pipeInfo
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- JPS61266126A JPS61266126A JP11004085A JP11004085A JPS61266126A JP S61266126 A JPS61266126 A JP S61266126A JP 11004085 A JP11004085 A JP 11004085A JP 11004085 A JP11004085 A JP 11004085A JP S61266126 A JPS61266126 A JP S61266126A
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- steel pipe
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Abstract
Description
【発明の詳細な説明】
〔産業−にの利用分野〕
この発明は大径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に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a bent steel pipe by hot bending a large diameter welded steel pipe.
近時、ラインパイプの需要増加にともなって、大径溶接
ベンド鋼管の需要が増加し、その性質も高強度と高靭性
とが要求されるようになった。Recently, with the increase in demand for line pipes, the demand for large-diameter welded bent steel pipes has increased, and their properties are also required to have high strength and high toughness.
外径が１６”以」−の大径溶接ベント管を製造する方法
は、大きく分けて、直状溶接鋼管を冷間で曲げ加工する
方法と、熱間で曲げ加工を行う方法の２つがある。There are two main methods for manufacturing large-diameter welded bent pipes with an outer diameter of 16" or more: cold bending of straight welded steel pipes and hot bending. .
前者の冷間で曲げ加工を行う方法は、曲げ加工において
熱を加えないため、加工前と加工後で性能に大差はない
が、加工に大きな力を必要とするため、設備が犬がかり
となり、工数も増加するのみならず、製造できる管寸法
が制限される欠点がある。The former method, which performs cold bending, does not apply heat during bending, so there is not much difference in performance before and after bending, but since it requires a large amount of force for bending, it requires a lot of equipment. This method not only increases the number of man-hours but also has the disadvantage that the pipe dimensions that can be manufactured are limited.
これに対し、後者の熱間で曲げ加工を行う方法は、加工
が容易で、設備面、工数面で有利であるが、加工時の加
熱のために、材料特性が変化し、特に溶接部とその周辺
の靭性の低下が大きな問題となっている。On the other hand, the latter method of hot bending is easy to process and is advantageous in terms of equipment and man-hours, but the heating during processing changes the material properties, especially in the welded part. Deterioration of toughness in the surrounding area has become a major problem.
直状の大径溶接鋼管の製造においては、現在ＡＰＩ規格
により内外面からの溶接が義務づけられており、その溶
接は能率面から大入熱のサブマージアーク溶接で行うの
が通例とされ、更に内外面をそれぞれ１層で溶接するの
が効率的とされている。In the manufacture of straight large-diameter welded steel pipes, API standards currently require welding from the inside and outside surfaces, and from the standpoint of efficiency, submerged arc welding with high heat input is generally used for welding, and It is considered efficient to weld each outer surface in one layer.
しかしながら、前述した曲げ加工時の加熱に伴う靭性の
低下は、この溶接時の大入熱に原因があるとされている
。したがって、溶接ベンド鋼管の製造においては、サブ
マージアーク溶接による内外面者１層溶接は行われてお
らず、もっばら、被覆溶接棒を用いた小人熱の手溶接、
あるいは小電流のＭＩＧ溶接で、しかも多層溶接が行わ
れているが、当然のことながら、これらの溶接ではザブ
マージアーク溶接と比べて、１０〜２０倍の工数がかか
り、製造能率の大巾低下を余儀なくされる。However, the aforementioned decrease in toughness due to heating during bending is said to be caused by the large heat input during welding. Therefore, in the production of welded bent steel pipes, submerged arc welding is not used for single-layer welding of the inner and outer surfaces, but manual welding using dwarf heat using coated welding rods,
Alternatively, multi-layer welding is performed using MIG welding with a small current, but of course these welds require 10 to 20 times more man-hours than submerged arc welding, resulting in a significant drop in manufacturing efficiency. be forced to.
本発明の目的は、熱間で曲げ加工を行う大径溶接ベンド
鋼管の製造において、直状溶接鋼管の製造ノ際にサブマ
ージアーク溶接による内外面者１層溶接を行っても、な
お高靭性、高強度の得られるベンド鋼管製造方法を提供
することにある。An object of the present invention is to provide high toughness even when single-layer welding is performed on the inner and outer surfaces by submerged arc welding during the production of straight welded steel pipes in the production of large-diameter welded bent steel pipes that are subjected to hot bending. It is an object of the present invention to provide a method for producing a bent steel pipe that provides high strength.
なお、本発明の製造方法が目標とするベンド鋼管の強度
はＸ−６５級（ＡＰＩ）以上であり、靭性はシャルピー
衝撃試験値（ｖＥ−３０）で８に９ｆ−ｍ以上である。The strength of the bent steel pipe targeted by the manufacturing method of the present invention is at least X-65 grade (API), and the toughness is at least 8 to 9 f-m in Charpy impact test value (vE-30).
従来、大径溶接鋼管の製造において、ＡＰＩ規格を満足
するために、素材組成面からは、たとえばＮｂ−Ｖ系の
鋼が使用されている。しかし、この鋼を使用しても、曲
げ加工に際して行う高周波加熱により強度、靭性を損う
ことは避けられなかった。また、熱処理面からも種々の
改良が加えられているが、直管でしか十分な成果は挙っ
ていない。Conventionally, in the manufacture of large-diameter welded steel pipes, Nb-V steel, for example, has been used in terms of material composition in order to satisfy API standards. However, even if this steel was used, it was inevitable that the strength and toughness would be impaired due to high frequency heating performed during bending. In addition, various improvements have been made in terms of heat treatment, but sufficient results have only been achieved with straight pipes.
その原因は、組成改良、熱処理条件の改良といった対策
がそれぞれ別個に実施されていた点にあると考えられる
。The reason for this is thought to be that measures such as improving the composition and improving the heat treatment conditions were each taken separately.
本発明は熱間による曲げ加工を前提として、素材組成か
らその熱処理条件はもとより、圧延条件、溶接金属成分
、曲げ加工条件および加工後の熱処理条件までを総括的
に規定して、ベンド鋼管の強度確保と靭性確保を図った
もので、その要旨とするところは、Ｃ： ０．０２−０
．１０ｗｔ％、Ｓｉ ： ０．２０ｗｔ係以下、Ｍｎ
： １．６０ ｗｔｑ６以下、Ｍｏ ： ０．１０ ｗ
ｔ％以下、Ｔｉ ： ０．００８−０．０２０ｗｔ％、
Ｂ ： ０．０００８〜０．００４ｗｔ％、残部Ｆｅお
よび不純物からなり下式で求められる炭素当量Ｃｅｑが
０．２５〜０．３５ ｗｔ％である鋼をＡｃ３点〜１２
８０℃の温度に加熱してから圧延を開始し、６９０〜８
００℃の温度で圧延を終了後放冷するかまたは６９０〜
８００℃の温度で圧延を終了後当該温度から４５０℃以
下の温度まで５〜ｂの速度で強制冷却して得られた鋼板
を素材として、シーム部溶接金属がＭｏ ： ０．０７
ｗｔ％以下、Ｏ：３００ｐｐｍ以下、Ｎ：５０ｐｐｍ
以下を含有し下式で求められる炭素当量Ｃｅｑが０．
２８〜０．３８ｗｔ％ である直状溶接鋼管をつくり、
当該鋼管のベンド予定部を誘導加熱によりＡｃ３点〜（
Ａｃ３点＋８０℃）の温度に５分以内加熱している間に
曲げ加工を終え、直ちに焼入れ後、Ａｃ １点以下の温
度で焼戻すことを特徴とする高強度・高靭性ベンド鋼管
の製造方法にある。The present invention is based on the premise of hot bending, and comprehensively defines not only the material composition and heat treatment conditions, but also the rolling conditions, weld metal components, bending conditions, and post-forming heat treatment conditions. The aim is to ensure that C: 0.02-0.
．． 10wt%, Si: 0.20wt or less, Mn
: 1.60 wtq6 or less, Mo: 0.10 w
t% or less, Ti: 0.008-0.020wt%,
B: 0.0008 to 0.004 wt%, the balance is Fe and impurities, and the steel whose carbon equivalent Ceq calculated by the following formula is 0.25 to 0.35 wt% is Ac3 to 12
Start rolling after heating to a temperature of 80°C,
After finishing rolling at a temperature of 00°C, let it cool or at a temperature of 690°C to
After finishing rolling at a temperature of 800°C, a steel plate obtained by forced cooling from that temperature to a temperature of 450°C or less at a rate of 5 to b is used as a material, and the seam weld metal has Mo: 0.07
wt% or less, O: 300ppm or less, N: 50ppm
Contains the following and has a carbon equivalent Ceq determined by the following formula of 0.
A straight welded steel pipe with a content of 28 to 0.38 wt% was made,
The bend area of the steel pipe is heated by induction heating to Ac 3 points (
A method for producing a high-strength, high-toughness bent steel pipe, characterized in that the bending process is completed while heating to a temperature of Ac3 point + 80°C for less than 5 minutes, immediately quenched, and then tempered at a temperature of Ac1 point or less. It is in.
Ｃｅｑ ＝Ｃ＋” Ｍｎ＋ ’ （Ｃｕ ＋Ｎｉ） ＋
′−（Ｃｒ ＋Ｍｏ’ ＋Ｖ ）以下、本発明を工程順
に詳細に説明する。Ceq =C+"Mn+' (Cu +Ni) +
'-(Cr +Mo' +V) Hereinafter, the present invention will be explained in detail in the order of steps.
単に素材鋼の強度と靭性を高めるだけでは目的を達成し
得ない。溶接ならびに熱間向げまでを考慮して成分組成
を調整する必要がある。Simply increasing the strength and toughness of the steel material will not achieve the objective. It is necessary to adjust the component composition taking into account welding and hot processing.
Ｃ：強度を確保するために必要な元素で、００２ｗｔ％
未満では必要強度を得られず、０．１０ ｗｔ％を超え
ると、サブマージアーク溶接等の大入熱溶接の場合に溶
接部が硬化し靭性を低下させるので、０．０２〜０．１
０ｗｔ％の範囲とする。C: Element necessary to ensure strength, 002wt%
If it is less than 0.10 wt%, the weld will harden and the toughness will decrease in the case of high heat input welding such as submerged arc welding, so if it is 0.02 to 0.1
The range is 0wt%.
Ｓｉ： 製鋼時に脱酸剤として必要な元素であるが、０
．２０ｗｔ％を超えると、溶接熱影響部（ＨＡＺ）の組
織が粗粒化し、靭性を低下させるので、０．２０ｗｔ係
以下とする。Si: An element necessary as a deoxidizing agent during steel manufacturing, but 0
．． If it exceeds 20 wt%, the structure of the weld heat affected zone (HAZ) becomes coarse grained and the toughness decreases, so the content is set to 0.20 wt% or less.
Ｍｎ： 脱酸剤として必要で、強度、靭性を向上させる
が、１．．６０ ｗｔ％を超えると、大入熱溶接の場合
に溶接部か硬化し靭性を低下させるので、１，６０ｗｔ
％以下とする。Mn: Necessary as a deoxidizer and improves strength and toughness, but 1. ．． If it exceeds 60 wt%, the welded part will harden and the toughness will decrease in the case of high heat input welding, so 1.60 wt%
% or less.
Ｍｏ二 強度を向上させるのに有効な元素であるが、
反面、溶接部の靭性低下の原因となるので、０．１０ｗ
ｔ％を上限とする。Mo2 is an effective element for improving strength, but
On the other hand, 0.10w causes a decrease in the toughness of the welded part.
The upper limit is t%.
Ｔｉ：Ｂの有効利用と、オーステナイト粒の微細化効果
による靭性向上とを目的に添加するが、０００８ｗｔ％
未満ではその目的達成に不十分である。Ti: Added for the purpose of effective use of B and improvement of toughness by refining austenite grains, but 0008wt%
Less than that is insufficient to achieve the objective.
反面、微量添加でも有効に作用し、０．０２ｗｔ％を超
える添加は不経済であるので、０．００８〜０．０２ｗ
ｔ％の範囲とする。On the other hand, even a small amount of addition works effectively, and addition of more than 0.02wt% is uneconomical, so 0.008 to 0.02w
The range is t%.
Ｂ：炭素当ｔ（Ｃｅｑ）を上げることなく高張力化を可
能にし、その効果は熱間で曲げ加工を実施した場合にも
不変であるが、０．０００８ ｗＬ係未満では十分な効
果を上げることができず、０．００４ｗｔ％を超える添
加では溶接部のへ性を低下させるので、ｏ、ｏｏｏｓ〜
０．００４ ｗｔ％の範囲とする。B: Enables high tensile strength without increasing carbon equivalent t (Ceq), and the effect remains unchanged even when hot bending is performed, but it is sufficiently effective at less than 0.0008 wL coefficient. Addition of more than 0.004 wt% will reduce the bendability of the weld, so o,ooos~
The range is 0.004 wt%.
Ｃｅｑ ：強度と靭性のバランスを図り、０．２５ｗｔ
％では強度が不足し、０．３５ｗｔ％を超えると靭性が
不足するので、０．２５〜０．３５ｗｔ％の範囲とする
。Ceq: 0.25wt with a balance of strength and toughness
%, the strength will be insufficient, and if it exceeds 0.35 wt%, the toughness will be insufficient, so the range is set to 0.25 to 0.35 wt%.
素材鋼に対し、Ａｃ３点〜１２８０℃の温度で圧延を開
始し、６９０〜８００℃の温度で圧延を終了する。Rolling of the raw steel is started at a temperature of Ac3 point to 1280°C, and rolling is finished at a temperature of 690 to 800°C.
その理由は次のとおりである。The reason is as follows.
オーステナイト組織にフェライト組織が混入するのを防
ぐため、圧延開始温度をＡｃ３点以上にとらなければな
らないが、１２８０℃を超えると、オーステナイト粒が
過大になり、靭性低下を招くので、圧延開始温度をＡＣ
３点〜１２８０℃とした。In order to prevent the ferrite structure from being mixed into the austenite structure, the rolling start temperature must be set to Ac3 point or higher; however, if it exceeds 1280°C, the austenite grains become excessively large, leading to a decrease in toughness, so the rolling start temperature must be A.C.
3 points to 1280°C.
圧延終了温度については、８００℃を超える温度で圧延
を終了した場合、組織の微細化が不十分で、靭性低下を
招き、また、強度のバラツキが大きくなる可能性を生じ
る。逆に、６９０℃未満で圧延を終了した場合は、変態
を終了したフェライト組織に加工を加えることになるの
で、加工歪が残存したままとなり、同様に靭性低下を招
く。したがって、６９０〜ＳＯＯ℃の範囲とした。Regarding the rolling end temperature, if rolling is ended at a temperature exceeding 800° C., the microstructure will not be sufficiently refined, leading to a decrease in toughness and possibly increasing variations in strength. On the other hand, if rolling is completed at a temperature lower than 690° C., processing is applied to the ferrite structure that has completed transformation, so processing strain remains, which similarly causes a decrease in toughness. Therefore, the temperature was set to be in the range of 690 to SOO°C.
圧延を終了した材料は次の３つの方法のいずれかで冷却
を行う。After rolling, the material is cooled using one of the following three methods.
■ そのまま常温まで放冷する。■ Leave to cool to room temperature.
■ ４５０℃以下まで５〜５０°Ｃ／ｓｅｃの速度で強
制冷却した後、常温まで放冷する。(2) Forced cooling to below 450°C at a rate of 5 to 50°C/sec, then allowed to cool to room temperature.
■ 常温まで５〜ｂ
■〜■は要求される強度と靭性のバランスによって適宜
使いわけられる。■ Up to room temperature 5~b ■~■ can be used as appropriate depending on the balance of strength and toughness required.
すなわち、強度より靭性を重視する場合は■の放冷を用
い、強度、靭性ともに必要とする場合は■の強制冷却子
放冷を用いる。そして、強制冷却終了温度を低くとるほ
ど、強度に重点がおかれ、■の常温まで強制冷却を行う
場合に最も大きい強度が得られる。That is, when toughness is more important than strength, use the cooling method (2), and when both strength and toughness are required, use the forced cooler cooling method (2). The lower the forced cooling end temperature is, the more emphasis is placed on strength, and the greatest strength is obtained when forced cooling is performed to room temperature (2).
■■の場合に強制冷却終了温度を４５０℃以下に限定し
たのは、これより高い温度で強制冷却を終了するとその
目的である強度上昇効果が得られないためである。また
、その冷却速度を５〜５０℃の範囲に限定したのは、５
℃／ｓｅｅ未満では強制冷却による強度向上の効果が得
られず、５０℃／ｓｅｃを超える速度では組織が焼入れ
組織に変化してしまうためである。The reason why the forced cooling end temperature was limited to 450° C. or lower in the case of ■■ is that if the forced cooling ends at a temperature higher than this, the intended strength-increasing effect cannot be obtained. In addition, the cooling rate was limited to a range of 5 to 50°C.
This is because if the cooling rate is less than 50°C/sec, the strength improvement effect due to forced cooling cannot be obtained, and if the cooling rate exceeds 50°C/sec, the structure changes to a hardened structure.
素材鋼板の厚みは、大径鋼管用として一般に使用されて
いる鋼板の厚みに準じ、通常６〜５０．８ｍｍである。The thickness of the material steel plate is generally 6 to 50.8 mm, in accordance with the thickness of steel plates commonly used for large diameter steel pipes.
素材鋼板をオープンシーム管に成形し、そのシーム部を
溶接する。The raw steel plate is formed into an open seam tube, and the seam is welded.
溶接部においては母材に溶加材が加わって溶接金属の化
学成分が決定される。したがって、素材鋼の成分組成を
規制するだけでは、溶接部の機械的性質を満足させるこ
とはできない。本発明では溶接金属の化学成分が下記範
囲に修まるよう、ワイヤ等の溶加材を選択使用する。In the weld, filler metal is added to the base metal to determine the chemical composition of the weld metal. Therefore, it is not possible to satisfy the mechanical properties of the weld simply by regulating the chemical composition of the steel material. In the present invention, a filler metal such as wire is selected and used so that the chemical composition of the weld metal falls within the following range.
Ｍｏ ： ５性低下を低下させるので含有しないほう
が望ましいが、０．０７ｗｔ％までは許容できるので、
０．０７ｗｔ係以下とする。Mo: It is preferable not to contain Mo as it reduces the 5% deterioration, but up to 0.07 wt% is permissible.
It should be 0.07wt or less.
０、Ｎ：熱間曲げ加工後に靭性を低下させる原因となる
ので、Ｏについては３００ ｐｐｍ以下、ＮについてＩ
ｔ、 ５０ ｐｐｍ以１曲こそれぞれ制限する。0, N: Because it causes a decrease in toughness after hot bending, O is 300 ppm or less, N is I
Restricted to one song each of 50 ppm or more.
Ｃｅｑ ：溶接金属の強度と靭性のバランスを大きく支
配し、（１，２８ｗｔ％未満で（４強度が不足し、（）
３８ ｗｔ％を超えると靭性が不足するので、０，２８
〜０、３８ ｗｔ％の範囲とする。Ceq: It largely controls the balance between the strength and toughness of the weld metal, and if it is less than 1.28 wt% (4 strength is insufficient,
If it exceeds 38 wt%, the toughness will be insufficient, so 0.28 wt%
~0.38 wt%.
他の成分については、通常の溶加材を使用する限り特に
問題はないので、あえて限定はしないが、参考までに述
べると、次のとおりである。Regarding the other components, there are no particular problems as long as ordinary filler materials are used, so they are not limited, but for reference, they are as follows.
Ｃ：少ない場合は強度か不足し、多い場合は靭性が不足
するので、００４〜（］、１１ｗｔの範囲が望ましい。C: If it is less, the strength will be insufficient, and if it is more, the toughness will be insufficient, so a range of 004 to (], 11wt is desirable.
Ｓｉ 、 Ｍｎ 、 Ｔｉ 、 １３ ：多いと靭性低
下の原因になるので、Ｓｉｉζついては０．３０ｗｔ１
以下、Ｍｎ については］、６６０ｗ１％以下Ｔｊ
については０．０５ｗｔ％以下、Ｂについては０．００
５ｗｔ％以下にそれぞれ制限するのが望ましい。Si, Mn, Ti, 13: If too large, it causes a decrease in toughness, so for Siiζ, 0.30wt1
Below, regarding Mn], 660w1% or less Tj
0.05wt% or less for B, 0.00 for B
It is desirable to limit each to 5 wt% or less.
開先、成形方式、溶接手法については限定の必要がなく
、従来一般に行われているものに準じればよい。There is no need to limit the groove, forming method, and welding method, and it is sufficient to follow those commonly used in the past.
たとえば、成形方式はＵＯ方式、コンティニュアスロー
ルフォーミング方式（ＣＦＥ方式）、ベンディ／グロー
ル方式、スパイラル方式などが一般的であり、溶接はＵ
Ｏ方式、ＣＦＥ方式、ペンテイングロール方式において
は仮伺溶接後、内外面本溶接を行い、スパイラル方式に
おいては内外面本溶接のみを行うのが一般的である。こ
の場合、仮イ」溶接はＣＯ２ガス溶接で行うことが多い
。また、内外面本溶接はＭＩＧ溶接、ＴＩＧ溶接などの
小人熱溶接による多層盛でもよいが、能率面からは大入
熱のザブマージアーク溶接が望ましく、なかでも内外釜
１層溶接を推奨できる。本発明の製造方法は前述のとお
り大入熱のザブマージアーク溶接により内外面釜１層溶
接を行ってもなお、高強度・高靭性の確保できることを
前提に開発されたものである。For example, common forming methods include the UO method, continuous roll forming method (CFE method), bendy/growl method, and spiral method, and the welding method is the UO method.
In the O method, CFE method, and pent-roll method, after preliminary welding, the inner and outer surfaces are actually welded, and in the spiral method, only the inner and outer surfaces are actually welded. In this case, temporary welding is often performed by CO2 gas welding. In addition, for the actual welding of the inner and outer surfaces, multi-layer welding using dwarf heat welding such as MIG welding or TIG welding may be used, but from the standpoint of efficiency, submerged arc welding with a large heat input is preferable, and single-layer welding of the inner and outer hooks is particularly recommended. . As mentioned above, the manufacturing method of the present invention was developed on the premise that high strength and high toughness can be ensured even when single-layer welding of the inner and outer pots is performed by submerged arc welding with large heat input.
溶接後、必要に応じて、形状矯正のため、拡管工程を入
れてもよいことは言うまでもない。It goes without saying that after welding, a tube expansion step may be performed to correct the shape, if necessary.
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、加熱には、短時間
で所定温度まで加熱でき、かつ局部加熱が可能な誘導加
熱を採用する。If the entire large-diameter steel pipe is exposed to high temperatures for a long period of time, the softened steel pipe will deform due to its own weight. Therefore, induction heating is used for heating, which can heat up to a predetermined temperature in a short time and can locally heat the product.
また、加熱保持時間を長くした場合、高周波誘導加熱で
は、通常の加熱炉では見られない異常粒（粗粒）成長が
現われる。この異常粒成長は加熱保持時間が約５分を超
えると始まる。この粒成長を抑制するためと、鋼管の変
形を抑制するために、鋼管の加熱保持時間を５分以内に
抑え、この間に曲げ加工を終了する。Furthermore, when the heating holding time is increased, abnormal grain (coarse grain) growth appears in high-frequency induction heating, which is not seen in a normal heating furnace. This abnormal grain growth begins when the heating holding time exceeds about 5 minutes. In order to suppress this grain growth and to suppress deformation of the steel pipe, the heating and holding time of the steel pipe is limited to 5 minutes or less, and the bending process is completed during this time.
加熱温度は、オーステナイト組織にフェライト組織が混
入するのを防止するため、Ａｃ３点以上とするが、過熱
はオーステナイト組織の粗粒化を招くので、ＡＣ３点」
−８０℃以下に抑える。The heating temperature should be set to AC3 or higher to prevent the ferrite structure from mixing with the austenite structure, but overheating will cause the austenite structure to become coarser, so the AC3 point should be set.
Keep the temperature below -80℃.
曲げ加工方法は局部加熱部に曲げモーメントを作用させ
る方法であれば何れでもよく、たとえば環状誘導加熱コ
イルと該コイル後段に配した環状冷却リングと被処理管
の輸送方向先端部を把持して局部加熱部に曲げモーメン
トを付与する旋回アームとを備える所謂高周波曲げ加工
法が最適である。The bending method may be any method as long as it applies a bending moment to the local heating part. For example, the annular induction heating coil, the annular cooling ring placed after the coil, and the tip of the tube to be processed in the transport direction are held and the local heating part is bent. The so-called high-frequency bending method, which includes a rotating arm that applies a bending moment to the heating section, is optimal.
加工の際の加熱範囲を加工予定部分に極力限定すべきこ
とは言うまでもない。It goes without saying that the heating range during processing should be limited to the area to be processed as much as possible.
曲げ加工後は、加熱部分を直ちに急冷して、加工部分が
変形するのを防止するとともに、この部分の硬度を向上
させる。After the bending process, the heated part is immediately rapidly cooled to prevent the processed part from deforming and to improve the hardness of this part.
〔焼戻し〕
曲げ加工後の急冷にて生じた焼入れ組織を除去し、曲げ
加工部分の靭性を確保するため、焼戻しを行う。[Tempering] Tempering is performed to remove the quenched structure generated during rapid cooling after bending and to ensure the toughness of the bent portion.
この熱処理はＡｃ１点以下の温度で行うので、自重によ
る変形はない。Since this heat treatment is performed at a temperature below the Ac1 point, there is no deformation due to its own weight.
加熱は、上述の如く、自重による変形の危険がないので
、誘導加熱に限定する必要はなく、一般の加熱炉で十分
と言える。As mentioned above, since there is no risk of deformation due to its own weight, there is no need to limit the heating to induction heating, and a general heating furnace is sufficient.
次に実施例を説明する。Next, an example will be described.
８種類の鋼を用いて本発明法と比較法とにより各種の大
径溶接ベンド鋼管を製造した。Various large-diameter welded bent steel pipes were manufactured using eight types of steel by the method of the present invention and the comparative method.
素材鋼（Ａ−Ｈ）の化学成分、その圧延条件（圧延後の
冷却条件を含む）、素材鋼板を成形、溶接し、イ４＋ら
れた直状溶接鋼管を更に熱間で曲げ加工してずケられた
ベント鋼管の焼入れ温度、焼戻し温度、ならびにこの焼
戻しにより得られた製品ベンド鋼管の寸法およ０・ベン
ト部腹側（背側より性能力る）より採取した母材部の性
能を第１表に示す。The chemical composition of the raw material steel (A-H), its rolling conditions (including cooling conditions after rolling), the raw material steel plate formed and welded, and the straight welded steel pipe that has been subjected to I4+ bending without further hot bending. The quenching temperature and tempering temperature of the bent steel pipe, the dimensions of the product bent steel pipe obtained by this tempering, and the performance of the base material sampled from the ventral side of the bent part (from the dorsal side) were measured. It is shown in Table 1.
また、第２表には溶接時の入熱用、（内外面とも）溶接
金属の化学成分、曲げ加工により得られたベント鋼管の
焼入れ温度、焼戻し温度、ならびに製品ベンド鋼管のベ
ンド部から採取した溶接部の性能を示す。Table 2 also shows the heat input during welding, the chemical composition of the weld metal (both inside and outside), the quenching temperature and tempering temperature of the bent steel pipe obtained by bending, and the temperature of the bent steel pipe sampled from the bend part of the product bent steel pipe. Indicates the performance of the weld.
他の条件は次のとおりである。Other conditions are as follows.
素材鋼はＸ開先を伺与後、ＵＯプレス方式により成形し
、ＣＯ２自動溶接による仮付溶接後、内外面上もにザブ
マージアーク溶接による１層溶接を行った。溶加材は市
販の６０〜８０キロ級の高張力鋼用ザブマージアーク溶
接材料を用いた。After creating an X-groove, the material steel was formed using the UO press method, and after tack welding using CO2 automatic welding, single-layer welding was performed on the inner and outer surfaces using submerged arc welding. As the filler metal, a commercially available submerged arc welding material for high tensile strength steel of 60 to 80 kg class was used.
曲げ加工における加熱は誘導加熱により行い、加熱保持
時間は１分間であった。曲げ加工後の焼入れは水冷にて
行い、焼戻しは通常の加熱炉に１時間保持することによ
り行った。Heating during the bending process was performed by induction heating, and the heating time was 1 minute. Hardening after bending was performed by water cooling, and tempering was performed by holding in a normal heating furnace for 1 hour.
母材部性能のうち引張試験はＡＰＩ規格による試験片で
行い、ＹＰは０．５係伸びでの耐力［相］死ねＴＳは引
張強さくＫ９ｆＡｎｌｌ）、Ｅｅは伸び（俸）である。Among the properties of the base material, the tensile test was performed using a test piece according to the API standard, where YP is the proof stress [phase] at 0.5 modulus of elongation, TS is the tensile strength (K9fAnll), and Ee is the elongation (salary).
溶接部の引張強さについてはＡＰＩ規格に規定する継手
引張強さを示し、その値に付与されたＭは母材部破断を
表わしている。Regarding the tensile strength of the welded part, the joint tensile strength specified in the API standard is shown, and the M given to that value represents the base metal fracture.
シャルピー試験は母材部、溶接部ともＪＩ８４号試験片
にて行い、ｖＴｓは破面遷移温度（℃）、ｖＥ−３０は
一３０℃での吸収エネルギー（ＩＷ−ｍ）である。The Charpy test was conducted using JI 84 test pieces for both the base metal part and the welded part, where vTs is the fracture surface transition temperature (°C), and vE-30 is the absorbed energy at -30°C (IW-m).
合否は本発明が目標とするＸ−６５級（ＡＰ Ｉ）以上
でンヤルピー衝撃値ｖＥ ３０Ｂ”Ｗ ｍ以上のもの
を○、いずれか一方でもこれらを下回るものを×として
表示した。Pass/fail was indicated as ○ if it was higher than the X-65 class (API) which is the target of the present invention and had a Nyal Rupee impact value vE 30B''Wm or higher, and × if it was lower than either of these values.
第１表および第２表から明らかなように、鋼ＡはＳｉ、
Ｍｏ、 Ｂが本発明範囲外であるあで、圧延条件、焼
入れ焼戻し温度が本発明範囲内であるにもかかわらず、
母材部の強度（ＹＰ）が目標を下回っている。また、溶
接金属においてもＭｎが本発明範囲を超えており、溶接
部の靭性が目標を下回っている（第２表）。As is clear from Tables 1 and 2, Steel A contains Si,
Although Mo and B are outside the range of the present invention, the rolling conditions, and the quenching and tempering temperature are within the range of the present invention,
The strength (YP) of the base material is below the target. Furthermore, Mn in the weld metal exceeds the range of the present invention, and the toughness of the welded part is below the target (Table 2).
鋼Ｂは成分組成が本発明範囲内であるので、圧延条件お
よび焼入れ焼戻し温度が本発明範囲のものは満足のいく
母材部性能を示しく第１表）、溶接金属の成分組成も本
発明範囲内で、溶接部性能も目標を−に回っている（第
２表）。しかし、焼入れ温度が本発明範囲外のものは母
材部の強度（ＹＰ）、’ＩＷ性ならびに溶接部の靭性が
目標を下回り、圧延条件が本発明範囲外のものも母材部
の靭性（ｖＥ−３０）が目標を下回っている（第１表、
第２表）。Steel B has a composition within the range of the present invention, so if the rolling conditions and quenching and tempering temperatures are within the range of the present invention, it exhibits satisfactory base metal performance (Table 1), and the composition of the weld metal is also within the range of the present invention. Within the range, the weld performance was also below the target (Table 2). However, when the quenching temperature is outside the range of the present invention, the strength (YP) of the base metal, the IW property, and the toughness of the weld zone are lower than the targets, and when the rolling conditions are outside the range of the present invention, the toughness of the base metal (YP) is lower than the target. vE-30) is below the target (Table 1,
Table 2).
鋼ＣはＭｎ、Ｂか本発明範囲外で、母材部の強度（ＹＰ
、ＴＳ）が目標を下回っている。溶接部の強度も目標を
下回っているが、これは母材強度が低いためで、母材強
度が十分であれば溶接部については満足のいく性能を示
すものである。Steel C has Mn and B, which are outside the scope of the present invention, and the strength of the base material (YP
, TS) are below the target. The strength of the welded part is also lower than the target, but this is due to the low strength of the base metal; if the strength of the base metal is sufficient, the welded part will show satisfactory performance.
鋼りは成分組成が本発明範囲内であるので、圧延条件、
焼入れ焼戻し温度か本発明範囲のものは母材部性能が目
標を−４＝回っているが（第１表）、溶加材等との関係
で溶接金属の成分組成が本発明範囲外となっており、そ
の結果、溶接部の靭性が目標を下回っている（第２表）
。また、焼入れ温度の不足するものは母材部の靭性が悪
く、圧延条件の仕上げ温度が高すぎるものは母材部の強
度（ＹＰ、ＴＳ）、靭性ともに目標を下回っている（第
１表）。Since the steel has a composition within the range of the present invention, the rolling conditions,
When the quenching and tempering temperature was within the range of the present invention, the base metal performance was -4 below the target (Table 1), but the composition of the weld metal was outside the range of the present invention due to the relationship with the filler metal, etc. As a result, the toughness of the weld is below the target (Table 2)
. In addition, those with insufficient quenching temperature have poor toughness of the base metal, and those with too high finishing temperature under rolling conditions have both strength (YP, TS) and toughness of the base metal below the target (Table 1). .
鋼Ｅは成分組成か本発明範囲であるので、圧延条件、焼
入れ焼戻し温度が本発明範囲のものは満足のいく母材部
性能を示しく第１表）、溶接金属の成分組成も本発明範
囲内に修まっているので、溶接部も満足のいく性能を示
している（第２表）。Steel E has a composition within the range of the present invention, so those whose rolling conditions and quenching and tempering temperatures are within the range of the present invention exhibit satisfactory base metal performance (Table 1), and the composition of the weld metal is also within the range of the present invention. The welded parts also show satisfactory performance (Table 2).
しかし、焼入れ温度の低いものは母材部の強度（ＹＰ、
ＴＳ）が低く（第１表）、溶接部もその成分組成が本
発明範囲内であるにもかかわらず、靭性が悪い（第２表
）。However, the strength of the base material (YP,
TS) is low (Table 1), and the welded part has poor toughness even though its composition is within the range of the present invention (Table 2).
鋼ＦはＭｏが多過ぎ、溶接金属においてもＭ。Steel F has too much Mo, and the weld metal also contains M.
が過大となっている。その結果、他の条件が全て本発明
範囲内であるにもかかわらず、母材部の強度（ＹＰ、Ｔ
Ｓ）が低く、溶接部も靭性が不足している（第１表、第
２表）。is excessive. As a result, although all other conditions were within the scope of the present invention, the strength of the base material (YP, T
S) is low, and the welded part also lacks toughness (Tables 1 and 2).
鋼Ｇは成分組成が本発明範囲内に修まっているので、他
の条件が本発明範囲内のものは母材部、溶接部ともに満
足のいく性能を有しているが、焼入れ温度の高過ぎるも
のは母材部、溶接部の双方で靭性が不足している（第１
表、第２表）。Steel G has a composition within the range of the present invention, so steels with other conditions within the range of the present invention have satisfactory performance in both the base metal part and the welded part, but the high quenching temperature If the toughness is too high, both the base metal and the welded part lack toughness (first
Table, Table 2).
鋼ＨはＣｅｑが低過ぎているので、他の条件が全て本発
明範囲内にあるにもかかわらず、母材部の靭性が不足し
ている（第１表）。ただし、溶接部については溶加材等
との関係で成分組成が本発明範囲内に修まっているので
、満足のいく性能を示している。Since Steel H has too low Ceq, the base metal lacks toughness even though all other conditions are within the scope of the present invention (Table 1). However, since the composition of the welded part is within the range of the present invention in relation to the filler metal, it shows satisfactory performance.
また、ｆυ拐部性能、溶接部性能ともに目標を上回って
いる鋼Ｂについての製造方法（加熱温度：１１００℃、
イ１トげ温度ニア００℃、水冷停止温度：４５０℃、冷
却速度］５°Ｃ／ｓｅｃ、焼入れ温度：９００℃、５１
、ｑ戻し温度５８０°Ｃ）において、水冷停干、温度の
みを４５０℃超の５５０℃に変更したところ、−１Ｂ
１１の強度かＹ、 Ｐ−＝４５．２ Ｋ９ｆ、４＝］
、 ＴＳ ＝ ５７．３ Ｋ９ｆ、４ｕｌを目標値を
下回った。In addition, the manufacturing method for steel B (heating temperature: 1100°C,
I1 Tow temperature near 00℃, water cooling stop temperature: 450℃, cooling rate] 5℃/sec, quenching temperature: 900℃, 51
, q return temperature 580°C), water cooling stagnation, and changing only the temperature to 550°C, which is higher than 450°C, -1B
11 strength or Y, P-=45.2 K9f, 4=]
, TS = 57.3 K9f, 4ul was below the target value.
同しく、冷却速度のみを５０℃／ｓｅｃ超の６０’Ｃ／
ｓｅｃに変更したところ、母材の靭性かｖＥ ３０
＝ ２．３’ｌｆ ｍと１」標値を下回った。Similarly, only the cooling rate was changed to 60'C/sec over 50'C/sec.
When changed to sec, the toughness of the base material vE 30
= 2.3'lf m and 1'' below the target value.
同じく、焼戻し温度のみをＡＣ１点超Ｏ７２０°Ｃに変
更した古ころ、靭性が母材部でｖＥ −３０＝ ５．６
’４．ｆ−＋ｎ、溶接部てｖＥ−３０＝２．１に９ｆ−
ｒｎとなりいづれも目標価を下回った。Similarly, for old rollers in which only the tempering temperature was changed to 720°C above AC1 point, the toughness of the base material was vE -30 = 5.6
'4. f-+n, welded part vE-30=2.1 to 9f-
rn, both of which were below the target price.
また、曲げ加工における加熱保持時間のみを１分間から
５分間を超える１５分間に変更したところ、旬（」部に
おいて異常粒度成長が認められ、強度、靭性ともに（Ｙ
Ｐ＝４３．２に吟佃、ＴＳ＝５２．７覇’ｚｆ＋Ｊ。In addition, when only the heating holding time during bending was changed from 1 minute to 15 minutes (more than 5 minutes), abnormal grain size growth was observed in the grain size (Y), and both strength and toughness decreased (Y
Gintsukuda at P=43.2, TS=52.7 H'zf+J.
ｖＥ−３０＝］、２に＋Ｍ−ｍ）目標値を下回った。vE-30=], 2+M-m) below the target value.
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、直状溶接鋼管の製造工程において大入熱のザブマ
ージアーク溶接で内外面各１層溶接を行った後、熱間曲
げ加工を行っても、加工部全体に高度の強度と靭性とが
伺力され、これにより製品価値の高い高品質のベント鋼
管が簡単な設備で能率よく低コストで製造される。As is clear from the above explanation, according to the manufacturing method of the present invention, in the manufacturing process of straight welded steel pipes, one layer each of the inner and outer surfaces is welded by submerged arc welding with large heat input, and then hot bending is performed. Even if this process is carried out, a high degree of strength and toughness is achieved throughout the processed part, and as a result, high-quality bent steel pipes with high product value can be manufactured efficiently and at low cost using simple equipment.
Claims (1)
ｗｔ％以下、Ｍｎ：１．６０ｗｔ％以下、Ｍｏ：０．１
０ｗｔ％以下、Ｔｉ：０．００８〜０．０２０ｗｔ％、
Ｂ：０．０００８〜０．００４ｗｔ％、残部Ｆｅおよび
不純物からなり下式で求められる炭素当量Ｃｅｑが０．
２５〜０．３５ｗｔ％である鋼をＡｃ＿３点〜１２８０
℃の温度に加熱してから圧延を開始し、６９０〜８００
℃の温度で圧延を終了後放冷するかまたは６９０〜８０
０℃の温度で圧延を終了後当該温度から４５０℃以下の
温度まで５〜５００℃／ｓｅｃの速度で強制冷却して得
られた鋼板を素材として、シーム部溶接金属がＭｏ：０
．０７ｗｔ％以下、Ｏ：３００ｐｐｍ以下、Ｎ：５０ｐ
ｐｍ以下を含有し下式で求められる炭素当量Ｃｅｑが０
．２８〜０．３８ｗｔ％である直状溶接鋼管をつくり、
当該鋼管のベンド予定部を誘導加熱によりＡｃ＿３点〜
（Ａｃ＿３点＋８０℃）の温度に５分以内加熱している
間に曲げ加工を終え、直ちに焼入れ後、Ａｃ＿１点以下
の温度で焼戻すことを特徴とする高強度・高靭性ベンド
鋼管の製造方法。 Ｃｅｑ＝Ｃ＋１／６Ｍｎ＋１／１５（Ｃｕ＋Ｎｉ）＋１
／５（Ｃｒ＋Ｍｏ＋Ｖ）(1) C: 0.02-0.10wt%, Si: 0.20
wt% or less, Mn: 1.60wt% or less, Mo: 0.1
0 wt% or less, Ti: 0.008 to 0.020 wt%,
B: 0.0008 to 0.004 wt%, the balance consisting of Fe and impurities, and the carbon equivalent Ceq determined by the following formula is 0.
Ac_3 points ~ 1280 for steel that is 25 ~ 0.35 wt%
Start rolling after heating to a temperature of 690-800 °C.
After finishing rolling at a temperature of 690 to 80 °C, leave it to cool.
After finishing rolling at a temperature of 0°C, a steel plate obtained by forced cooling from that temperature to a temperature of 450°C or less at a rate of 5 to 500°C/sec is used as a material, and the seam weld metal is Mo: 0.
．． 07wt% or less, O: 300ppm or less, N: 50p
pm or less and the carbon equivalent Ceq determined by the following formula is 0
．． A straight welded steel pipe with a content of 28 to 0.38 wt% was made,
The bend area of the steel pipe is heated to Ac_3 points by induction heating.
A method for producing a high-strength and high-toughness bent steel pipe, characterized in that the bending process is completed while heating to a temperature of (Ac_3 point + 80°C) for less than 5 minutes, immediately quenched, and then tempered at a temperature of Ac_1 point or less. . Ceq=C+1/6Mn+1/15(Cu+Ni)+1
/5(Cr+Mo+V)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11004085A JPS61266126A (en) | 1985-05-22 | 1985-05-22 | Production of high-strength high-toughness bent steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11004085A JPS61266126A (en) | 1985-05-22 | 1985-05-22 | Production of high-strength high-toughness bent steel pipe |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61266126A true JPS61266126A (en) | 1986-11-25 |
Family
ID=14525585
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11004085A Pending JPS61266126A (en) | 1985-05-22 | 1985-05-22 | Production of high-strength high-toughness bent steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61266126A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS632588A (en) * | 1986-06-23 | 1988-01-07 | Kawasaki Steel Corp | Welded steel pipe waving excellent site weldability |
| JPH0790375A (en) * | 1993-09-28 | 1995-04-04 | Sumitomo Metal Ind Ltd | Production of thick bend steel pipe having high strength and high toughness |
| JPH07503923A (en) * | 1992-12-22 | 1995-04-27 | エイチ・ピー―ケミー・ペルザー・リサーチ・アンド・デイベロツプメント・リミテツド | Automotive base unit |
| JP2002316283A (en) * | 2001-02-16 | 2002-10-29 | Kawasaki Steel Corp | Method of manufacturing extra-low-carbon steel welded joint having excellent welded joint toughness |
| US7780800B2 (en) * | 2007-05-16 | 2010-08-24 | Sumitomo Metal Industries, Ltd. | Method of manufacturing a bent pipe |
| WO2011148859A1 (en) * | 2010-05-25 | 2011-12-01 | 株式会社神戸製鋼所 | High strength welded metal having excellent ctod characteristics |
| CN102294380A (en) * | 2010-06-25 | 2011-12-28 | 上海月月潮钢管制造有限公司 | Method for manufacturing medium-temperature and high-pressure steel pipe |
| CN103084427A (en) * | 2012-07-09 | 2013-05-08 | 上海月月潮钢管制造有限公司 | Manufacturing method of hardenability steel tube |
| CN105081002A (en) * | 2014-05-21 | 2015-11-25 | 河北宇鹏重工管道装备制造有限公司 | Manufacturing process for X80 steel grade D1422*30.8 medium frequency induction heating roasted bent pipes |
| EP3636787A4 (en) * | 2017-05-22 | 2020-09-30 | Nippon Steel Corporation | Bent steel pipe and method for producing same |
-
1985
- 1985-05-22 JP JP11004085A patent/JPS61266126A/en active Pending
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS632588A (en) * | 1986-06-23 | 1988-01-07 | Kawasaki Steel Corp | Welded steel pipe waving excellent site weldability |
| JPH07503923A (en) * | 1992-12-22 | 1995-04-27 | エイチ・ピー―ケミー・ペルザー・リサーチ・アンド・デイベロツプメント・リミテツド | Automotive base unit |
| JPH0790375A (en) * | 1993-09-28 | 1995-04-04 | Sumitomo Metal Ind Ltd | Production of thick bend steel pipe having high strength and high toughness |
| JP2002316283A (en) * | 2001-02-16 | 2002-10-29 | Kawasaki Steel Corp | Method of manufacturing extra-low-carbon steel welded joint having excellent welded joint toughness |
| KR101175420B1 (en) * | 2007-05-16 | 2012-08-20 | 수미도모 메탈 인더스트리즈, 리미티드 | Bend pipe and process for manufacturing the same |
| US7780800B2 (en) * | 2007-05-16 | 2010-08-24 | Sumitomo Metal Industries, Ltd. | Method of manufacturing a bent pipe |
| WO2011148859A1 (en) * | 2010-05-25 | 2011-12-01 | 株式会社神戸製鋼所 | High strength welded metal having excellent ctod characteristics |
| JP2012006073A (en) * | 2010-05-25 | 2012-01-12 | Kobe Steel Ltd | High strength welded metal excellent in ctod characteristic |
| CN102294380A (en) * | 2010-06-25 | 2011-12-28 | 上海月月潮钢管制造有限公司 | Method for manufacturing medium-temperature and high-pressure steel pipe |
| CN103084427A (en) * | 2012-07-09 | 2013-05-08 | 上海月月潮钢管制造有限公司 | Manufacturing method of hardenability steel tube |
| CN103084427B (en) * | 2012-07-09 | 2014-08-13 | 上海月月潮钢管制造有限公司 | Manufacturing method of hardenability steel tube |
| CN105081002A (en) * | 2014-05-21 | 2015-11-25 | 河北宇鹏重工管道装备制造有限公司 | Manufacturing process for X80 steel grade D1422*30.8 medium frequency induction heating roasted bent pipes |
| CN105081002B (en) * | 2014-05-21 | 2017-03-01 | 河北宇鹏重工管道装备制造有限公司 | X80 steel-grade D1422*30.8 Frequency Induction Heating simmers the manufacturing process of bend pipe processed |
| EP3636787A4 (en) * | 2017-05-22 | 2020-09-30 | Nippon Steel Corporation | Bent steel pipe and method for producing same |
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