JPH0441619A - Production of resistance welded tube excellent in toughness at low temperature - Google Patents
Production of resistance welded tube excellent in toughness at low temperatureInfo
- Publication number
- JPH0441619A JPH0441619A JP14926290A JP14926290A JPH0441619A JP H0441619 A JPH0441619 A JP H0441619A JP 14926290 A JP14926290 A JP 14926290A JP 14926290 A JP14926290 A JP 14926290A JP H0441619 A JPH0441619 A JP H0441619A
- Authority
- JP
- Japan
- Prior art keywords
- cooling
- toughness
- resistance welded
- temperature
- temp
- 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.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 238000001816 cooling Methods 0.000 claims abstract description 87
- 230000009466 transformation Effects 0.000 claims abstract description 19
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 6
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 4
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 4
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 18
- 239000010959 steel Substances 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 14
- 238000000034 method Methods 0.000 abstract description 12
- 238000003303 reheating Methods 0.000 abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 5
- 229910052748 manganese Inorganic materials 0.000 abstract description 3
- 239000000203 mixture Substances 0.000 abstract description 3
- 229910052742 iron Inorganic materials 0.000 abstract description 2
- 230000001276 controlling effect Effects 0.000 abstract 1
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 238000003466 welding Methods 0.000 description 16
- 239000000463 material Substances 0.000 description 15
- 229910000859 α-Fe Inorganic materials 0.000 description 13
- 230000000694 effects Effects 0.000 description 10
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 4
- 229910001562 pearlite Inorganic materials 0.000 description 4
- 239000010953 base metal Substances 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 230000000171 quenching effect Effects 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
本発明は、電縫鋼管の溶接部・靭性を改善した、低温靭
性に優れた電縫鋼管の製造方法に関するものである。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for manufacturing an ERW steel pipe having improved welded portions and toughness and excellent low-temperature toughness.
本発明は電縫鋼管製造後、管全体を熱処理することなく
、電縫溶接直後のシーム加熱後の冷却条件を適正化する
ことにより、母材部と同程度の溶接部靭性を有する、低
温靭性に優れた電縫鋼管の製造方法を提供するものであ
る。The present invention achieves low-temperature toughness that has the same degree of weld toughness as the base material by optimizing the cooling conditions after seam heating immediately after ERW welding without heat-treating the entire pipe after manufacturing ERW steel pipes. The present invention provides an excellent method for manufacturing ERW steel pipes.
〈従来の技術〉
近年、北海、アラスカ、シヘリアでの原油採掘が活発化
しており、これに伴い低温靭性に優れた鋼管への要求が
高まっている。さらに、客先では綱材購入コスト削減の
ため、安価な鋼管を欲し７ている。即ち、安価で且つ低
温靭性に優れた鋼管に対する要求が非常に高まっている
のが現状である。<Conventional Technology> In recent years, oil extraction in the North Sea, Alaska, and Sicheria has become more active, and as a result, demand for steel pipes with excellent low-temperature toughness has increased. Furthermore, customers want inexpensive steel pipes to reduce the cost of purchasing rope materials. That is, the current situation is that there is an extremely increasing demand for steel pipes that are inexpensive and have excellent low-temperature toughness.
従来から母材部については、制御圧延、制御冷却等の技
術により、優れた低温靭性が得られるようになってきた
。しかし、電縫溶接部については、圧延組織が溶接時に
消失してしまい粗大な鋳造組織が形成されるため、低温
靭性が母材部に対して大幅に劣化することが大きな問題
となっている。Conventionally, it has become possible to obtain excellent low-temperature toughness for the base material using techniques such as controlled rolling and controlled cooling. However, with regard to electric resistance welded parts, the rolling structure disappears during welding and a coarse cast structure is formed, so that low-temperature toughness is significantly deteriorated compared to the base metal part, which is a major problem.
これらを解消し、母材部と同等レベルの靭性を確保する
ため、電縫溶接後、電縫部近傍をオーステナイト域まで
再加熱（空冷）する、シームノルマ法が一般的に適用さ
れている。これにより、電縫部の靭性は改善されるもの
の、依然、母材部より劣る。この理由は、再加熱後空冷
されるため、母材部に比べて粗大なフェライトａ織が生
成するためである。最近の客先からの靭性要求レベルに
対しては、このようなシームノルマ法では対処出来ず、
再加熱後水冷、あるいは水冷後再再加熱する等により、
電縫部組織の微細化を図り、靭性の改善を狙っている。In order to eliminate these problems and ensure the same level of toughness as the base material, the seam norm method is generally applied, which involves reheating (air cooling) the vicinity of the electrical resistance welding part to the austenite region after electrical resistance welding. Although this improves the toughness of the electrical resistance welded portion, it is still inferior to the base material portion. The reason for this is that since the material is air cooled after reheating, a ferrite a weave that is coarser than that of the base material is generated. The seam norm method cannot meet the toughness requirements of recent customers.
By water cooling after reheating, or reheating after water cooling, etc.
The aim is to improve toughness by making the electric resistance weld structure finer.
しかしこれらの冷却条件は電縫部組織やその硬度に対し
て大きな影響を与え、場合によってはかえって靭性を劣
化させてしまうおそれがある。However, these cooling conditions have a large effect on the electrical resistance welding structure and its hardness, and in some cases may even deteriorate the toughness.
先行技術としては、特公平２−４０８号公報（を縫綱管
シーム溶接部の冷却方法）がある。同技術では、電縫部
の再加熱後の冷却ゾーンでの冷却条件と造管速度を検出
−演算するシステムにより、水冷部の冷却速度を算出し
、これをフ。・−ドパツクすることで冷却条件をコント
ロールするものである。同技術では、冷却設備について
のハード、ソフト面について記述されているものの、冶
金学的見地での冷却制御については一切触れていない。As a prior art, there is Japanese Patent Publication No. 2-408 (method for cooling seam welds of draped tubes). This technology uses a system that detects and calculates the cooling conditions and pipe forming speed in the cooling zone after reheating the electric resistance welding section to calculate the cooling speed of the water cooling section, and then calculates this. - Cooling conditions are controlled by pumping. Although this technology describes the hardware and software aspects of cooling equipment, it does not mention cooling control from a metallurgical perspective at all.
また、特開昭５９−３５６２９号公報（低温靭性に優れ
た高張力電縫鋼管の製造方法）記載のものは、電縫溶接
後７５０〜１０５０℃に加熱し、さらに、７５０〜９５
０℃の温度から３０〜１５０℃／秒で急冷し、微細なア
シキュラーフェライト組織を形成させ、電縫部の靭性を
改善させる技術であり、冷却パターン、冷却停止温度等
についての記載がなくただ一様に冷却することになって
いる。In addition, the method described in JP-A-59-35629 (method for manufacturing high-tensile resistance welded steel pipes with excellent low-temperature toughness) is heated to 750 to 1050°C after resistance welding, and further heated to 750 to 950°C.
This is a technology that rapidly cools at 30 to 150°C/second from a temperature of 0°C to form a fine acicular ferrite structure and improve the toughness of the electric resistance welded part. It is supposed to be cooled down accordingly.
〈発明が解決しようとする課題〉
本発明は電縫部の低温靭性を母材部と同等以上に改善し
た、低温靭性に優れた電縫鋼管を安価に提供することを
目的する。<Problems to be Solved by the Invention> An object of the present invention is to provide, at a low cost, an electric resistance welded steel pipe with excellent low temperature toughness, in which the low temperature toughness of the electric resistance welded portion is improved to be equal to or higher than that of the base material portion.
〈課題を解決するための手段〉
本発明の前記の課題は、電縫部の再加熱後の水冷速度、
冷却停止温度を適正に制御することにより、微細なフェ
ライト組織を形成させ、さらに、硬度についても母材部
と同レベルとすることで、解決され得る。<Means for Solving the Problems> The above-mentioned problems of the present invention are to improve the water cooling rate after reheating the electric resistance welding part,
This problem can be solved by appropriately controlling the cooling stop temperature to form a fine ferrite structure, and by making the hardness the same as that of the base material.
本発明の要旨とするところは、Ｃ： ０．０５〜０．２
０％、Ｓｉ ： ０．３％以下：Ｍｎ： ０．５０〜２
．００％を基本成分とし、Ｎｂ：０．０１〜０，１０％
、Ｖ二０．０１〜０．１０％、Ｔｉ：０．０１〜０．０
５％の１種または２種以上を含み、残部Ｆｅ及び不可避
的不純元素よりなる電縫鋼管の電縫溶接部を８５０〜１
０００℃に加熱した後、＾ｒ３変態点以上から冷却速度
３０〜１００℃／秒で急速冷却し、停止温度をその鋼の
（Ａｒｔ ｓｏｏＣ）から（＾ｒ、−１００℃）とし
た後、弱冷却することを特徴とする低温靭性に優れた電
縫鋼管の製造方法にある。The gist of the present invention is that C: 0.05 to 0.2
0%, Si: 0.3% or less: Mn: 0.50-2
．． 00% is the basic component, Nb: 0.01-0.10%
, V2 0.01-0.10%, Ti: 0.01-0.0
The electric resistance welded part of an electric resistance welded steel pipe containing 5% of one or more types and the balance consisting of Fe and unavoidable impurity elements is 850 to 1
After heating to 000℃, rapid cooling is performed from above the ^r3 transformation point at a cooling rate of 30 to 100℃/sec to bring the stopping temperature from the (Art sooC) of the steel to (^r, -100℃), and then The present invention provides a method for manufacturing an ERW steel pipe having excellent low-temperature toughness, which is characterized by cooling.
本発明に従い、前記の如く電縫部加熱後の強制冷却時の
冷却速度、冷却停止温度を限定し、さらに弱冷却を組み
合わせることにより、溶接部低温靭性に優れた電縫鋼管
を製造することができる。According to the present invention, as described above, by limiting the cooling rate and cooling stop temperature during forced cooling after heating the ERW part, and further combining weak cooling, it is possible to manufacture an ERW steel pipe with excellent low-temperature toughness of the weld part. .
以下、本発明の詳細な説明する。The present invention will be explained in detail below.
まず素材の成分系について説明する。First, the composition of the material will be explained.
Ｃは必要な強度を確保するために必要な元素であり、０
．０５％以上とした。しかし、Ｃ量があまり高すぎる場
合、母材部、電縫部共に低温靭性を劣化させるため、上
限を０．２０％とした。C is an element necessary to ensure the necessary strength, and 0
．． 05% or more. However, if the C content is too high, the low-temperature toughness of both the base material portion and the electric resistance welding portion deteriorates, so the upper limit was set to 0.20%.
Ｓｉについては、電縫溶接の安定性の観点から０、３％
以下とする。Regarding Si, 0.3% from the viewpoint of stability of electric resistance welding.
The following shall apply.
ＭｎについてはＣと同様に強度確保には欠かせない元素
であり、０．５０％以上とした。また、２．００％を越
えた場合中心偏析部が硬化し、靭性の劣化をもたらすた
め、上限を２．００％とした。Like C, Mn is an essential element for ensuring strength, and was set at 0.50% or more. Moreover, if it exceeds 2.00%, the central segregation part will harden and the toughness will deteriorate, so the upper limit was set at 2.00%.
以上の元素を基本成分とするが、母材部の低温靭性向上
のためＮｂ、 Ｖ、 Ｔｉの１種または２種以上を添加
することが有効である。Although the above elements are the basic components, it is effective to add one or more of Nb, V, and Ti to improve the low-temperature toughness of the base material.
Ｎｂは熱間圧延時でのオーステナイト粒の微細化に効果
的であり、その後の変態により生成するフェライト粒が
細粒となるため低温靭性向上には非常に有効である。こ
のようなＮｂ添加の効果を得るには、０．０１％以上の
添加が必要である。また、０．１０％を超えて添加して
も効果は変わらないため、上限は０．１０％とした。Nb is effective in refining austenite grains during hot rolling, and since the ferrite grains produced through subsequent transformation become finer grains, Nb is very effective in improving low-temperature toughness. In order to obtain such an effect of Nb addition, it is necessary to add 0.01% or more. Furthermore, since the effect remains unchanged even if added in an amount exceeding 0.10%, the upper limit was set at 0.10%.
■についてはフェライト変態後に炭窒化物として析出し
、フェライト粒の粗大化を抑制するため母材部の靭性改
善には効果的である。このような析出の効果を得るには
、０．０１％以上の添加が必要であり、また、０．１０
％を超えて添加してもその効果は向上しないため、上限
は０．１０％とした。As for (2), it precipitates as carbonitride after ferrite transformation and suppresses coarsening of ferrite grains, so it is effective in improving the toughness of the base material. To obtain such a precipitation effect, it is necessary to add 0.01% or more, and 0.10% or more is required.
Since the effect does not improve even if added in excess of 0.1%, the upper limit was set at 0.10%.
Ｔｉについても同様に炭窒化物を形成し粒成長を抑制す
る効果が０１０１％以上の添加で奏される。Similarly, Ti has the effect of forming carbonitrides and suppressing grain growth when added in an amount of 0.101% or more.
しかし、０．０５％を超えて添加してもその効果は変わ
らないので上限を０．０５％とした。However, the effect does not change even if it is added in an amount exceeding 0.05%, so the upper limit was set at 0.05%.
その他、Ｐ、Ｓは中心偏析、介在物の観点からできるだ
け少ない方が望ましい。In addition, it is desirable that P and S be as small as possible from the viewpoint of center segregation and inclusions.
以上の成分有する鋼を溶製したあと連続鋳造で鋳造し、
その後熱間圧延ミルにおいて、電縫鋼管用鋼帯とする。After melting steel with the above components, it is cast by continuous casting,
Thereafter, it is processed into a steel strip for electric resistance welded steel pipes in a hot rolling mill.
次に、電縫溶接部の加熱、冷却条件について述べる。Next, the heating and cooling conditions of the electric resistance welding section will be described.
本発明では電縫溶接後、電縫溶接部を８５０〜１０００
℃に加熱することで電縫溶接により生成した粗大な鋳造
組織を破壊するものである。即ち、加熱により電縫部を
オーステナイト組織に変態させるためには８５０℃以上
の温度が必要となる。また、あまり高温となるとオース
テナイト粒が粗大化し、靭性が劣化するため上限を１０
００℃とする。In the present invention, after the electric resistance welding, the electric resistance welded part is
By heating to ℃, the coarse cast structure generated by electric resistance welding is destroyed. That is, in order to transform the electric resistance welded portion into an austenite structure by heating, a temperature of 850° C. or higher is required. In addition, if the temperature is too high, the austenite grains will become coarser and the toughness will deteriorate, so the upper limit should be set to 10
00℃.
以上のように加熱された電縫部を強制冷却するが、その
冷却パターン、速度、停止温度が重要となる。本発明は
これらを適正に制御することにより微細なフェライト組
織を生成させ、また、冷却後の再加熱（焼戻し）を施す
ことなく母材と同等レベルの硬度を確保し、これにより
電縫部の靭性が母材部と同等の優れたレベルとすること
が可能となる。As described above, the heated electrical resistance welding section is forcibly cooled, and the cooling pattern, speed, and stopping temperature are important. The present invention generates a fine ferrite structure by controlling these appropriately, and also secures the same level of hardness as the base material without reheating (tempering) after cooling, thereby improving the toughness of the electric resistance welded part. It is possible to achieve the same excellent level as that of the base material.
冷却はシーム加熱直後に行うことが電縫部靭性の向上に
は効果的である。第１図にシーム加熱器１〜冷却ゾーン
２（＃１冷却ゾーン２ａ、＃２冷却ゾーン２ｂ）及び温
度測定器３の配置を示す。Cooling immediately after seam heating is effective in improving the toughness of the electrical resistance seam. FIG. 1 shows the arrangement of the seam heater 1 to the cooling zone 2 (#1 cooling zone 2a, #2 cooling zone 2b) and the temperature measuring device 3.
本発明ではシーム加熱器ｌ直後の＃１冷却ゾーン２ａで
Ａｒ３変態点以上から冷却し、その鋼の（Ａｒ、変態点
−５０℃）から（Ａｒ、変態点−１００℃）で冷却を終
了する。その後、＃２冷却ゾーン２ｂでは復熱を防止す
る程度の弱冷却を行う。急冷停止温度を（Ａｒ、変態点
−５０℃）から（Ａｒ変態点−１−１００℃）とした理
由は、測定している温度はあくまでパイプ外面温度であ
り、パイプ内面側とは温度差が存在するためである。即
ち、パイプ内面側まで確実にＡｒ、変態点以下とするた
めには、実測されるパイプ外面温度を（Ａｒ、変態点５
０℃）以下とすることが必要である。また、下限温度に
ついては、逆にパイプ外面側が急速冷却により硬化する
ことを防止するため、（Ａｒ、変態点−１−１００℃）
とした。このように前段域（＃１冷却ゾーン２ａ）で象
、速冷却することにより、Ａｒ３変態点後のフェライト
粒成長を抑制し細粒化できる効果がある。また、Ａｒ、
変態点より５０℃以下まで急冷することにより、靭性を
劣化させるパーライト組織を抑制する効果がある。この
ようにシーム加熱の冷却を前段急冷とすることで最も効
果的にフェライト粒の細粒化ができ、Ａｒ、変態点より
低温まで冷却することで第２相の生成が防止できる。In the present invention, cooling is performed from the Ar3 transformation point or higher in the #1 cooling zone 2a immediately after the seam heater 1, and cooling is completed from (Ar, transformation point -50°C) to (Ar, transformation point -100°C) of the steel. . Thereafter, in the #2 cooling zone 2b, weak cooling is performed to prevent heat recovery. The reason why the rapid cooling stop temperature was changed from (Ar, transformation point -50℃) to (Ar transformation point -1-100℃) is that the temperature being measured is only the outside surface temperature of the pipe, and there is a temperature difference from the inside surface of the pipe. Because it exists. In other words, in order to ensure that the inner surface of the pipe is below Ar, the transformation point, the actually measured pipe outer surface temperature must be (Ar, transformation point 5
It is necessary to keep the temperature below 0°C. In addition, regarding the lower limit temperature, in order to prevent the outer surface of the pipe from hardening due to rapid cooling, (Ar, transformation point -1-100℃)
And so. By performing rapid cooling in the pre-stage region (#1 cooling zone 2a) in this way, there is an effect of suppressing the growth of ferrite grains after the Ar3 transformation point and making the grains finer. Also, Ar,
Rapid cooling from the transformation point to 50° C. or lower has the effect of suppressing the pearlite structure that deteriorates toughness. In this way, the ferrite grains can be most effectively refined by performing rapid cooling in the first stage of seam heating, and the generation of the second phase can be prevented by cooling to a temperature lower than the Ar transformation point.
冷却速度の限定理由について述べる。＃１冷却ゾーンの
冷却速度は細粒フェライト組織を得るため３０℃／秒以
上必要である。但し、冷速が１００“０７秒を越えた場
合、パイプ外面部が硬化（焼入れ）組織となることがあ
るため上限は１００℃／秒とした。The reason for limiting the cooling rate will be explained. The cooling rate of #1 cooling zone is required to be 30° C./second or more in order to obtain a fine-grained ferrite structure. However, if the cooling rate exceeds 100°C/sec, the outer surface of the pipe may become hardened (quenched), so the upper limit was set at 100°C/sec.
＃１冷却ゾーンでの急冷を停止したあと、＃２冷却ゾー
ンでの弱冷却が是非必要である。＃１冷却ゾーンでＡｒ
＋ 変態点より低温まで冷却されても、その後空冷され
た場合は復熱することが考られるため、これを防止する
ためには＃２冷却ゾーンでの弱冷却が必要である。弱冷
却は復熱しない程度の冷却速度で且つ復熱しない温度域
まで連続して行う必要がある６実機ライン試験の結果、
１０〜２０℃／秒程度の冷却速度で３００ ’Ｃ以下ま
で冷却することが好ましい。After stopping rapid cooling in #1 cooling zone, weak cooling in #2 cooling zone is absolutely necessary. #1 Ar in cooling zone
+ Even if it is cooled to a temperature lower than the transformation point, if it is air cooled afterwards, it is likely that heat will recuperate, so to prevent this, weak cooling in the #2 cooling zone is necessary. As a result of 6 actual machine line tests, weak cooling must be performed at a cooling rate that does not regenerate and continuously up to a temperature range that does not regenerate.
It is preferable to cool down to 300'C or less at a cooling rate of about 10 to 20C/sec.
以上述べたように本発明では電縫部を加熱後、強制冷却
し、そのときの冷却速度、冷却停止温度の限定、並びに
復熱を防止するための弱冷却を組み合わせることにより
、電縫部の再加熱あるいは管全体の熱処理（焼戻し）を
することなく、母材部と同等レベルの優れた溶接部靭性
が得られる。As described above, in the present invention, after heating the ERW part, the ERW part is forcibly cooled, and the ERW part is reheated by limiting the cooling rate and cooling stop temperature at that time, and by combining weak cooling to prevent heat regeneration. Alternatively, excellent weld zone toughness equivalent to that of the base metal can be obtained without heat treating (tempering) the entire tube.
本発明での冷却速度、冷却停止温度の限定についてさら
に詳細に説明する。本発明は第２回（ア）に示すように
Ａｒｓ点以上からＡｒ１点より低い温度まで急冷し、そ
の後復熱を防止するため弱冷却することが特徴である。The limitations on the cooling rate and cooling stop temperature in the present invention will be explained in more detail. The present invention is characterized by rapid cooling from the Ars point or higher to a temperature lower than the Ar1 point, as shown in Part 2 (A), and then weak cooling to prevent reheating.
これに対して、（イ）に示すようにシーム加熱後空冷す
る従来からのシームノルマ法ではＡｒ＝ 、Ａｒ、点の
通過速度が遅く、従ってフェライト粒が粗大化すると共
に、パーライト組織が生成するため靭性が劣化する。ま
た（つ）に示す如（Ａｒ３点以上から急冷した場合でも
、その停止温度がＡｒｒ点超ではパーライト組織が生成
するため靭性が劣化する。さらに（１）のように急冷停
止温度がＡｒ＋点直下（Ａｒ、点からマイナス２０℃程
度）の場合は復熱により再び変態点を通過することによ
り靭性が劣化する。（オ）のように復熱しない温度域ま
で、例えば３００℃以下まで階、冷した場合にはパイプ
の外表面が硬化（特にシーム加熱時の熱影響部〕してし
まい、これを調整するためにはシーム部の再加熱、ある
いは管全体の熱処理が必要となる。以上より、本発明の
如く、電縫部加熱後の強制冷却時の冷却速度、冷却停止
温度を限定すること、及び弱冷却を組み合わせることが
溶接部靭性向上には効果的な手段である。On the other hand, as shown in (a), in the conventional seam norm method in which the seam is heated and then air cooled, the passing speed of the Ar=, Ar, point is slow, and therefore the ferrite grains become coarser and a pearlite structure is generated. Toughness deteriorates. In addition, as shown in (1) (even when quenching is performed from the Ar3 point or higher, if the stopping temperature exceeds the Arr point, a pearlite structure is generated and the toughness deteriorates.Furthermore, as shown in (1), the quenching stopping temperature is just below the Ar+ point. (Ar, about -20℃ from the point), the toughness deteriorates by passing through the transformation point again due to recuperation. If this happens, the outer surface of the pipe will harden (especially the heat-affected zone during seam heating), and to correct this, it will be necessary to reheat the seam or heat treat the entire pipe. As in the present invention, limiting the cooling rate and cooling stop temperature during forced cooling after heating the electric resistance welding part, and combining weak cooling are effective means for improving the toughness of the welded part.
本発明の実施例を表１に示し簡単に説明する。Examples of the present invention are shown in Table 1 and briefly described.
また従来方法についても比較検討した。表１の１〜７に
ついては本発明を実施した例である。表１に示す成分、
冷却条件により電縫溶接部の低温靭性（シャルピー試験
で評価）は母材部と同等レベルで良好である。一方、表
１の８〜１１は従来方法による結果を示している。表１
の８についてはシーム加熱後空冷する従来からのシーム
ノルマ法であり、この場合冷却速度が遅いため粗大フェ
ライトとパーライト組織となり、良好な靭性が得られな
い。同９．１０の例については冷却停止温度がＡｒ＋変
態点近傍のため冷却停止後の復熱によりフェライト粒が
粗大化するため良好な靭性が得られない。同１１につい
ては冷却速度が速すぎるため硬化し靭性が劣化する。以
上のように、本発明の如く綱の成分系と電縫部の冷却速
度、冷却停止温度を限定し、さらに復熱を防ぐための弱
冷却を組み合わせることにより、優れた電縫部低温靭性
が得られる。A comparative study was also made of conventional methods. Examples 1 to 7 in Table 1 are examples in which the present invention was implemented. Ingredients shown in Table 1,
Depending on the cooling conditions, the low-temperature toughness of the electric resistance welded part (evaluated by Charpy test) is good and at the same level as the base metal. On the other hand, Tables 8 to 11 in Table 1 show the results obtained by the conventional method. Table 1
8 is the conventional seam norm method in which the seam is heated and then air cooled; in this case, the cooling rate is slow, resulting in a coarse ferrite and pearlite structure, and good toughness cannot be obtained. In the case of Example 9.10, the cooling stop temperature is near the Ar+ transformation point, and good toughness cannot be obtained because the ferrite grains become coarse due to recuperation after the cooling stops. Regarding No. 11, the cooling rate is too fast, resulting in hardening and deterioration of toughness. As described above, excellent low-temperature toughness of the electric resistance welded part can be obtained by limiting the component system of the rope, the cooling rate and cooling stop temperature of the electric resistance welded part, and further combining weak cooling to prevent heat recuperation as in the present invention. .
〈発明の効果〉
本発明に従い、電縫部加熱後の強制冷却時の冷却速度、
冷却停止温度を限定すること、及び弱冷却を組み合わせ
ることにより、溶接部低温靭性に優れた電縫銅管を製造
することができる。<Effects of the Invention> According to the present invention, the cooling rate during forced cooling after heating the electric resistance welding part,
By limiting the cooling stop temperature and combining weak cooling, it is possible to manufacture an electric resistance welded copper tube with excellent low-temperature toughness at the welded part.
第１図は本発明を実施する設備の概略図を示す。
第２図はシーム加熱後の冷却パターンについて本発明と
従来技術とを比較したものである。FIG. 1 shows a schematic diagram of the equipment implementing the invention. FIG. 2 compares the cooling pattern after seam heating between the present invention and the prior art.
Claims (1)
純物よりなる電縫鋼管の電縫溶接部を８５０〜１０００
℃に加熱した後、Ａｒ＿３変態点以上から冷却速度３０
〜１００℃／秒で急速冷却し、停止温度をその鋼の（Ａ
ｒ＿１−５０℃）から（Ａｒ＿１−１００℃）とした後
、弱冷却することを特徴とする低温靭性に優れた電縫鋼
管の製造方法。[Claims] The basic components are C: 0.05-0.20% Si: 0.3% or less Mn: 0.50-2.00%, Nb: 0.01-0.10% V: 0.01 to 0.10% Ti: 0.01 to 0.05% The ERW welded part of an ERW steel pipe containing one or more of 0.01 to 0.05% and the balance being Fe and unavoidable impurities is 850 to 1000% Ti.
After heating to ℃, cooling rate 30 from Ar_3 transformation point or above
Rapid cooling is performed at ~100°C/sec, and the stopping temperature is set to the (A
A method for producing an electric resistance welded steel pipe with excellent low-temperature toughness, characterized in that the temperature is lowered from (r_1-50°C) to (Ar_1-100°C) and then cooled slightly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2149262A JPH0742509B2 (en) | 1990-06-07 | 1990-06-07 | Method for producing ERW steel pipe with excellent low temperature toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2149262A JPH0742509B2 (en) | 1990-06-07 | 1990-06-07 | Method for producing ERW steel pipe with excellent low temperature toughness |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0441619A true JPH0441619A (en) | 1992-02-12 |
| JPH0742509B2 JPH0742509B2 (en) | 1995-05-10 |
Family
ID=15471401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2149262A Expired - Fee Related JPH0742509B2 (en) | 1990-06-07 | 1990-06-07 | Method for producing ERW steel pipe with excellent low temperature toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0742509B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2991213A1 (en) * | 2012-06-05 | 2013-12-06 | Alstom Hydro France | PROCESS FOR WELDING TWO EDGES OF ONE OR MORE STEEL PARTS TO ONE ANOTHER AND FORCED DRIVEN OBTAINED BY SUCH A METHOD |
| EP3020840A4 (en) * | 2013-07-09 | 2016-08-03 | Jfe Steel Corp | Thick-walled electric resistance welded steel pipe for line pipe, and method for manufacturing said steel pipe |
| CN110055396A (en) * | 2019-04-26 | 2019-07-26 | 首钢集团有限公司 | Cooling means after a kind of HFI welding steel pipe welding |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2613824C2 (en) | 2012-04-13 | 2017-03-21 | ДжФЕ СТИЛ КОРПОРЕЙШН | High-strength thin-walled steel pipes welded by electric resistance welding with high impact strength and method of their production |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS578848A (en) * | 1980-06-19 | 1982-01-18 | Seiko Epson Corp | Microprogram control circuit |
| JPS6458253A (en) * | 1987-08-31 | 1989-03-06 | Canon Kk | Intraocular lens |
-
1990
- 1990-06-07 JP JP2149262A patent/JPH0742509B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS578848A (en) * | 1980-06-19 | 1982-01-18 | Seiko Epson Corp | Microprogram control circuit |
| JPS6458253A (en) * | 1987-08-31 | 1989-03-06 | Canon Kk | Intraocular lens |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2991213A1 (en) * | 2012-06-05 | 2013-12-06 | Alstom Hydro France | PROCESS FOR WELDING TWO EDGES OF ONE OR MORE STEEL PARTS TO ONE ANOTHER AND FORCED DRIVEN OBTAINED BY SUCH A METHOD |
| WO2013182582A1 (en) * | 2012-06-05 | 2013-12-12 | Alstom Renewable Technologies | Method for welding two edges of one or more steel parts to each other including a heat treatment step after the welding step: penstock obtained with such a method |
| CN104520060A (en) * | 2012-06-05 | 2015-04-15 | 阿尔斯通再生能源技术公司 | Method for welding two edges of one or more steel parts to each other including heat treatment step after the welding step: penstock obtained with such method |
| EP3020840A4 (en) * | 2013-07-09 | 2016-08-03 | Jfe Steel Corp | Thick-walled electric resistance welded steel pipe for line pipe, and method for manufacturing said steel pipe |
| US10385417B2 (en) | 2013-07-09 | 2019-08-20 | Jfe Steel Corporation | Heavy wall electric resistance welded steel pipe for line pipe and method for manufacturing the same |
| CN110055396A (en) * | 2019-04-26 | 2019-07-26 | 首钢集团有限公司 | Cooling means after a kind of HFI welding steel pipe welding |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0742509B2 (en) | 1995-05-10 |
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