JPH0158253B2 - - Google Patents
Info
- Publication number
- JPH0158253B2 JPH0158253B2 JP14659782A JP14659782A JPH0158253B2 JP H0158253 B2 JPH0158253 B2 JP H0158253B2 JP 14659782 A JP14659782 A JP 14659782A JP 14659782 A JP14659782 A JP 14659782A JP H0158253 B2 JPH0158253 B2 JP H0158253B2
- Authority
- JP
- Japan
- Prior art keywords
- electric resistance
- sec
- cooling
- temperature
- heating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000001816 cooling Methods 0.000 claims description 27
- 238000010438 heat treatment Methods 0.000 claims description 12
- 229910000859 α-Fe Inorganic materials 0.000 claims description 11
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 238000000034 method Methods 0.000 claims description 3
- 239000012535 impurity Substances 0.000 claims description 2
- 238000003466 welding Methods 0.000 description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 239000010953 base metal Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 230000007704 transition Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 229910011208 Ti—N Inorganic materials 0.000 description 2
- 125000002252 acyl group Chemical group 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000000879 optical micrograph Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/50—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for welded joints
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Description
【発明の詳細な説明】
本発明は電縫溶接部が母材部と同程度に低温靭
性のすぐれた高張力電縫鋼管の製造方法に関する
ものである。
従来の製造方法では母材部はコントロールドロ
ーリング、制御冷却により微細なフエライトがで
き、低温靭性のすぐれたものが得られるが、電縫
溶接部は圧延組織が消失し、粗大な鋳造組織が形
成され、また溶接から急冷されることによりクリ
ーンフエライトが出来ないため低温靭性が悪くな
るという欠点を有していた。
本発明は上記の欠点を有利に解消するものであ
り、その要旨とするところはＣ：0.01〜0.08％、
Mn≦1.5％、Si≦0.5％、Ｐ≦0.03％、Ｓ≦0.008
％、Ti≦0.04％、Nb：0.001〜0.050％、Ｖ：
0.001〜0.050％、Ｎ≦0.010％、残部Fe及び不可避
的不純物よりなる素材鋼板を用い電縫溶接し、そ
の後電縫溶接部を790℃〜1050℃で５秒以上加熱
し、770℃〜890℃の温度から30℃／sec〜150℃／
secで急冷し、電縫溶接部を微細アシキユラーフ
エライト組織にすることを特徴とする低温靭性の
すぐれた高張力電縫鋼管の製造方法である。
即ち本発明は素材の成分、電縫溶接した後の電
縫溶接部の加熱条件とその後の冷却条件を制限す
ることにより電縫溶接部が母材部と同程度に低温
靭性のすぐれた電縫鋼管を製造することを可能と
したもので極めて有利なものである。
次に本発明について詳細に説明する。
先ず素材の成分について述べるとＣについては
結晶粒微細化による靭性向上のため、0.01〜0.08
％とし、強度の点については他の元素にて補な
う。
Mnは1.5％より多量の場合、溶接性の点から悪
影響を及ぼすため1.5％以下が望ましくなる。
Siは強度を保たせる上で必要であるが0.5％よ
り多量の場合、電縫溶接部でのペネトレーターの
発生が容易となるため、0.5以下とする。
Ｐは偏析により亜影響を及ぼすのでＰは0.03％
以下とする。
ＳについてもMnSの長く伸ばされた介在物に
より靭性劣化するため低い方が望ましく0.008％
以下とする。
TiとＮは微細なTi−Ｎとして析出し、この微
細なTi−Ｎが溶接部の組織を微細化させ、靭性
を向上させる点からTiは0.04％以下、Ｎは0.010
％以下含有する。
Nb、Ｖにおいては強度確保上必要でNbは
0.001〜0.050％の範囲とし、Ｖは0.001〜0.050％
の範囲とする。
なお素材はAlで脱酸し、その際残存する通常
の量のAlを含有する。
次に電縫溶接部の加熱、冷却条件について述べ
る。本発明は電縫溶接後790℃〜1050℃の範囲で
５秒以上加熱するものであり、790℃未満では脆
化した溶接部の組織を改善するまでには至らず
1050℃超では粒の粗大化が起こり好ましくない。
又加熱時間が５秒未満では溶接部を完全に組織
改善することができず好ましくない。
冷却条件についても冷却開始温度を770℃〜870
℃とするもので、その冷却速度も30℃／sec〜150
℃／secとするものであり、その限定理由はアシ
キユラーフエライト析出はAr3点の変態点を通過
する時の速度が30℃／sec以上必要であり、その
上限も150℃／secが好ましい。
又温度についてもAr3点近傍の770℃以下にな
ると粒が微細にならないため好ましくなく、890
℃超から水冷を開始すると極めて微細な組織の改
善効果が認められなく好ましくないものである。
このような加熱、冷却条件について、本発明者
等は種々の実験を行ない第１図は電縫溶接後、
700℃〜1100℃の範囲において、５秒以上加熱し
た後、冷却速度を５℃／secと50℃／secと変えて
低温靭性について調べてみた。
その結果冷却速度が50℃／secのものは５℃／
secに比べ遷移温度（vTrS）は低くなり低温靭性
は向上することが明らかとなつた。
第２図は冷却開始温度770℃〜890℃の範囲にお
いて冷却速度の変化による遷移温度（vTrS）の
値をＣの含有量を変えて示したもので、Ｃ：0.08
％の含有量においては30℃／sec〜150℃／secの
範囲において、低温靭性が良くなつており、Ｃ：
0.15％の含有量においてはあまり良好な結果は得
られない。
第３図はＣ：0.08％の成分系における電縫溶接
後の光学顕微鏡写真（400倍）であり、電縫溶接
後、970℃で５秒加熱後、５℃／sec空冷した時の
(a)溶接部、(b)母材部と50℃／sec水冷した時の(c)
溶接部の組織を示す。
なお(a)はvTrS＝−20℃、フエライト粒度NO
＝10.9、(b)はvTrS＝−80℃、フエライト粒度NO
＝12.8、(c)はvTrS＝−40℃、フエライト粒度NO
＝12.6である。
即ち第３図から明らかなように電縫溶接後の加
熱、冷却条件を制御する本発明によればポストノ
ルマ（５℃／sec空冷）の粗大なフエライト粒に
比べ超微細なフエライト組織になり、母材部並の
フエライト粒度となり、低温靭性が良好となる。
以上のように本発明は電縫溶接後の加熱冷却条
件を790℃〜1050℃で５秒以上加熱し、冷却開始
温度を770℃〜890℃から30℃／sec〜150℃／sec
の冷却速度で水冷を行なうことにより溶接部でも
低温靭性の良好な電縫鋼管が得られるものでその
効果は極めて大である。
次に本発明の電縫鋼管の製造工程を第４図に示
すもので図中１は電縫溶接部、２は溶接ロール、
３はNO1ポストノルマライザー、４はNO2ポス
トノルマライザー、５はNO3ポストノルマライ
ザーで、その後６の水冷ゾーンを設置し、任意に
冷却開始温度、水冷冷却速度を設定するものであ
る。図中矢印は進行方向を示す。
次に本発明の実施例を表１に示す。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-strength electric resistance welded steel pipe in which the electric resistance welded portion has excellent low-temperature toughness comparable to that of the base metal portion. In conventional manufacturing methods, fine ferrite is formed in the base metal through controlled drawing and controlled cooling, resulting in a product with excellent low-temperature toughness, but in the electric resistance welded part, the rolled structure disappears and a coarse cast structure is formed. Moreover, since clean ferrite cannot be formed due to rapid cooling after welding, low-temperature toughness deteriorates. The present invention advantageously solves the above-mentioned drawbacks, and its gist is that C: 0.01-0.08%;
Mn≦1.5%, Si≦0.5%, P≦0.03%, S≦0.008
%, Ti≦0.04%, Nb: 0.001-0.050%, V:
0.001~0.050%, N≦0.010%, balance Fe and unavoidable impurities, weld by electric resistance welding using a steel plate, then heat the electric resistance welded part at 790°C to 1050°C for 5 seconds or more, and then heat it to 770°C to 890°C. From the temperature of 30℃/sec to 150℃/
This is a method for producing a high-tensile resistance welded steel pipe with excellent low-temperature toughness, which is characterized by rapid cooling at sec to form a fine axial ferrite structure in the resistance welded part. That is, the present invention provides an electric resistance welded part that has excellent low-temperature toughness comparable to that of the base material by limiting the composition of the material, the heating conditions for the electric resistance welded part after electric resistance welding, and the subsequent cooling conditions. It is extremely advantageous because it makes it possible to manufacture steel pipes. Next, the present invention will be explained in detail. First, regarding the ingredients of the material, C is 0.01 to 0.08 to improve toughness through grain refinement.
%, and the strength is supplemented with other elements. If the amount of Mn is more than 1.5%, it will have a negative effect on weldability, so it is preferable that the amount is 1.5% or less. Si is necessary to maintain strength, but if the amount is more than 0.5%, penetrators will easily occur in the electric resistance welding area, so it should be 0.5 or less. P has a sub-effect due to segregation, so P is 0.03%
The following shall apply. As for S, the longer MnS inclusions cause toughness deterioration, so a lower value is preferable, 0.008%.
The following shall apply. Ti and N precipitate as fine Ti-N, and this fine Ti-N refines the structure of the weld and improves toughness, so Ti is less than 0.04% and N is 0.010%.
Contains less than %. Nb and V are necessary to ensure strength, and Nb is
The range is 0.001 to 0.050%, and V is 0.001 to 0.050%.
The range shall be . The material is deoxidized with Al and contains the usual amount of Al that remains. Next, the heating and cooling conditions of the electric resistance welding section will be described. The present invention involves heating in the range of 790°C to 1050°C for 5 seconds or more after electric resistance welding, and heating below 790°C does not improve the brittle structure of the welded part.
If it exceeds 1050°C, the grains will become coarser, which is not preferable. Moreover, if the heating time is less than 5 seconds, the structure of the welded part cannot be completely improved, which is not preferable. Regarding cooling conditions, the cooling start temperature is 770℃~870℃.
℃, and the cooling rate is 30℃/sec to 150℃.
℃/sec, and the reason for this limitation is that acyl ferrite precipitation requires a speed of 30℃/sec or more when passing through the three transformation points of Ar, and the upper limit is also preferably 150℃/sec. . Regarding the temperature, if it is below 770℃, which is near the Ar 3 point, the grains will not become fine, which is undesirable.
If water cooling is started at a temperature exceeding .degree. C., the effect of improving extremely fine structures will not be observed, which is undesirable. The inventors conducted various experiments regarding such heating and cooling conditions, and Figure 1 shows the results after electric resistance welding.
After heating for 5 seconds or more in the range of 700°C to 1100°C, low-temperature toughness was investigated by changing the cooling rate to 5°C/sec and 50°C/sec. As a result, the cooling rate of 50℃/sec is 5℃/sec.
It has become clear that the transition temperature (vTrS) is lower than sec, and the low-temperature toughness is improved. Figure 2 shows the values of transition temperature (vTrS) due to changes in cooling rate in the cooling start temperature range of 770°C to 890°C with varying C content, C: 0.08
% content, the low-temperature toughness is improved in the range of 30°C/sec to 150°C/sec, and C:
Not very good results are obtained at a content of 0.15%. Figure 3 is an optical micrograph (400x) after electric resistance welding in a C: 0.08% component system.
(a) Welded part, (b) base metal part and (c) when water cooled at 50℃/sec
The structure of the weld is shown. Note that (a) is vTrS = -20℃, ferrite particle size NO
= 10.9, (b) is vTrS = -80℃, ferrite particle size NO
= 12.8, (c) is vTrS = -40℃, ferrite particle size NO
= 12.6. That is, as is clear from FIG. 3, according to the present invention, which controls the heating and cooling conditions after electric resistance welding, the ferrite structure becomes ultra-fine compared to the coarse ferrite grains of post-normal (5°C/sec air cooling). It has a ferrite grain size comparable to that of the base metal, and has good low-temperature toughness. As described above, the present invention has heating and cooling conditions after electric resistance welding, such as heating at 790°C to 1050°C for 5 seconds or more, and adjusting the cooling start temperature from 770°C to 890°C to 30°C/sec to 150°C/sec.
By performing water cooling at a cooling rate of , it is possible to obtain an ERW steel pipe with good low-temperature toughness even at the welded part, and the effect is extremely large. Next, the manufacturing process of the electric resistance welded steel pipe of the present invention is shown in Fig. 4, in which 1 is the electric resistance welded part, 2 is the welding roll,
3 is a NO1 post-normalizer, 4 is a NO2 post-normalizer, 5 is a NO3 post-normalizer, and after that, a water cooling zone 6 is installed, and the cooling start temperature and water cooling cooling rate can be set arbitrarily. Arrows in the figure indicate the direction of travel. Next, Table 1 shows examples of the present invention. 【table】
第１図は電縫溶接後の加熱温度と遷移温度との
関係を示す図、第２図は冷却速度と遷移温度との
関係を示す図、第３図ａ，ｂ，ｃはＣ：0.08％の
成分系における電縫溶接後の顕微鏡写真（400
倍）、第４図は本発明の電縫鋼管の製造工程を示
す説明図である。
１……電縫溶接部、２……溶接ロール、３……
NO1ポストノルマライザー、４……NO2ポスト
ノルマライザー、５……NO3ポストノルマライ
ザー、６……水冷ゾーン。
Figure 1 is a diagram showing the relationship between heating temperature and transition temperature after electric resistance welding, Figure 2 is a diagram showing the relationship between cooling rate and transition temperature, Figure 3 a, b, and c are C: 0.08% Micrograph after electric resistance welding in the component system (400
FIG. 4 is an explanatory diagram showing the manufacturing process of the electric resistance welded steel pipe of the present invention. 1...Erw welding part, 2...Welding roll, 3...
NO1 post-normalizer, 4...NO2 post-normalizer, 5...NO3 post-normalizer, 6...water cooling zone.
Claims (1)
Ｐ≦0.03％、Ｓ≦0.008％、Ti≦0.04％、Nb：
0.001〜0.050％、Ｖ：0.001〜0.050％、Ｎ≦0.010
％、残部Fe及び不可避的不純物よりなる素材鋼
板を用い電縫溶接し、その後電縫溶接部を790℃
〜1050℃で５秒以上加熱し、770℃〜890℃の温度
から30℃／sec〜150℃／secで急冷し、電縫溶接
部を微細アシキユラーフエライト組織にすること
を特徴とする低温靭性のすぐれた高張力電縫鋼管
の製造方法。1 C: 0.01-0.08%, Mn≦1.5%, Si≦0.5%,
P≦0.03%, S≦0.008%, Ti≦0.04%, Nb:
0.001-0.050%, V: 0.001-0.050%, N≦0.010
%, the remainder Fe and unavoidable impurities.
A low temperature process characterized by heating at ~1050°C for 5 seconds or more and rapidly cooling from a temperature of 770°C to 890°C at a rate of 30°C/sec to 150°C/sec to form a fine axial ferrite structure in the electric resistance weld. A method for manufacturing high-tensile electric resistance welded steel pipes with excellent toughness.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14659782A JPS5935629A (en) | 1982-08-24 | 1982-08-24 | Manufacture of high-tension electric-welded steel pipe having superior toughness at low temperature |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP14659782A JPS5935629A (en) | 1982-08-24 | 1982-08-24 | Manufacture of high-tension electric-welded steel pipe having superior toughness at low temperature |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5935629A JPS5935629A (en) | 1984-02-27 |
| JPH0158253B2 true JPH0158253B2 (en) | 1989-12-11 |
Family
ID=15411316
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP14659782A Granted JPS5935629A (en) | 1982-08-24 | 1982-08-24 | Manufacture of high-tension electric-welded steel pipe having superior toughness at low temperature |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5935629A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013153819A1 (en) | 2012-04-13 | 2013-10-17 | Ｊｆｅスチール株式会社 | High-strength thick-walled electric-resistance-welded steel pipe having excellent low-temperature toughness, and method for manufacturing same |
| KR102049834B1 (en) * | 2019-03-21 | 2019-11-28 | 에스큐아이소프트(주) | Digital signage making contents of sale marketing |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61117223A (en) * | 1984-11-14 | 1986-06-04 | Nippon Kokan Kk <Nkk> | Manufacture of bent pipe made of high toughness welding metal |
| JPS61238940A (en) * | 1985-04-12 | 1986-10-24 | Nippon Steel Corp | Low-temperature tough hardening steel excelling in toughness in weld zone |
| JPS61270337A (en) * | 1985-05-23 | 1986-11-29 | Nippon Steel Corp | Production of seam welded steel pipe having excellent stress corrosion cracking resistance in seam welded part |
| JPS61270338A (en) * | 1985-05-24 | 1986-11-29 | Nippon Steel Corp | Production of seam welded steel pipe having excellent stress corrosion cracking resistance in seam welded part |
| JPS621842A (en) * | 1985-06-26 | 1987-01-07 | Nippon Steel Corp | Tough, high tension steel having superior toughness in weld zone |
| JPS62180034A (en) * | 1986-02-04 | 1987-08-07 | Kawasaki Steel Corp | Ti-type uoe steel tube excellent in heat treatment characteristics in weld zone |
| JPS62202049A (en) * | 1986-02-28 | 1987-09-05 | Nippon Steel Corp | Electric welded tube having high resistance to selective corrosion in electric weld zone and its production |
-
1982
- 1982-08-24 JP JP14659782A patent/JPS5935629A/en active Granted
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013153819A1 (en) | 2012-04-13 | 2013-10-17 | Ｊｆｅスチール株式会社 | High-strength thick-walled electric-resistance-welded steel pipe having excellent low-temperature toughness, and method for manufacturing same |
| US9841124B2 (en) | 2012-04-13 | 2017-12-12 | Jfe Steel Corporation | High-strength thick-walled electric resistance welded steel pipe having excellent low-temperature toughness and method of manufacturing the same |
| KR102049834B1 (en) * | 2019-03-21 | 2019-11-28 | 에스큐아이소프트(주) | Digital signage making contents of sale marketing |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5935629A (en) | 1984-02-27 |
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