JPH02282427A - Manufacture of high strength steel pipe having low maximum hardness and yield ratio - Google Patents
Manufacture of high strength steel pipe having low maximum hardness and yield ratioInfo
- Publication number
- JPH02282427A JPH02282427A JP10144989A JP10144989A JPH02282427A JP H02282427 A JPH02282427 A JP H02282427A JP 10144989 A JP10144989 A JP 10144989A JP 10144989 A JP10144989 A JP 10144989A JP H02282427 A JPH02282427 A JP H02282427A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- temp
- yield ratio
- transformation point
- steel pipe
- 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.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 47
- 239000010959 steel Substances 0.000 title claims abstract description 47
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- 230000009466 transformation Effects 0.000 claims abstract description 25
- 238000001816 cooling Methods 0.000 claims abstract description 8
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 8
- 229910001562 pearlite Inorganic materials 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 8
- 229910001566 austenite Inorganic materials 0.000 abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052799 carbon Inorganic materials 0.000 abstract description 6
- 238000010438 heat treatment Methods 0.000 abstract description 5
- 238000005336 cracking Methods 0.000 abstract description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 4
- 238000005496 tempering Methods 0.000 description 4
- 150000003568 thioethers Chemical class 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000003345 natural gas Substances 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 229910000760 Hardened steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000012733 comparative method Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002343 natural gas well Substances 0.000 description 1
- 239000003129 oil well Substances 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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）
本発明は最高硬さと降伏比の低い高強度鋼管の製造法に
関するものである。DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing high-strength steel pipes with maximum hardness and low yield ratio.
（従来の技術とその問題点）
近年エネルギー開発の急速な進展により、石油ないしは
天然ガスのパイプライン輸送が大規模かつ長距離にわた
り行なわれるようになるとともに、破壊に対する安全性
の確保のために高強度の鋼管の製造が要請されている。(Conventional technology and its problems) Due to rapid progress in energy development in recent years, pipeline transportation of oil or natural gas has come to be carried out on a large scale and over long distances. There is a demand for manufacturing strong steel pipes.
またエネルギー資源の枯渇化に伴い新しく掘削される石
油井や天然ガス井は硫化物を含む場合が多く、石油や天
然ガスを輸送するパイプやそれらを貯蔵するタンク類に
、硫化物と鉄との反応によって発生した水素が鋼中に拡
散し、水素誘起割れや硫化物応力腐食割れを起し内容物
がもれる事故を時々起している。Furthermore, as energy resources are depleted, newly drilled oil and natural gas wells often contain sulfides, and the pipes that transport oil and natural gas and the tanks that store them are often made of sulfides and iron. Hydrogen generated by the reaction diffuses into the steel, causing hydrogen-induced cracking and sulfide stress corrosion cracking, sometimes resulting in leakage of contents.
このように石油等に含まれる硫化物が原因の割れについ
ては、一般に硬さが影響するものとして、低硬度の鋼管
の製造が要請されている。このような特性の要請に応じ
た鋼管の製造法として特開昭５４−１１７３１１号公報
、特開昭５５−７３８４９号公報などで紹介されている
焼入れ焼戻し処理法（Ｑ−Ｔ処理）、さらには特開昭５
３−５２２２８号公報、特開昭５４−１１８３２５号公
報などで紹介されているように低温で圧延する制御圧延
法（ＣＲ法）があり、一般に広く使用されている。Since cracks caused by sulfides contained in petroleum and the like are generally affected by hardness, there is a demand for manufacturing steel pipes with low hardness. As a manufacturing method for steel pipes that meet the demands for such characteristics, there is a quenching and tempering treatment method (Q-T treatment) introduced in JP-A-54-117311 and JP-A-55-73849, etc. Japanese Patent Application Publication No. 5
There is a controlled rolling method (CR method) in which rolling is carried out at a low temperature, as introduced in JP-A No. 3-52228, JP-A-54-118325, etc., and it is generally widely used.
また海底ラインパイプの場合のパージ船からの敷設性の
向上や、破壊に対する安全性の向上の要求から降伏比（
降伏強度／抗張力）の低い鋼管が必要とされている。し
かしながら高強度と低降伏比は相反する性質であり、両
者の性質を満足する鋼管は前記のような方法では得られ
なかった。In addition, in the case of submarine line pipes, the yield ratio (
Steel pipes with low yield strength/tensile strength are needed. However, high strength and low yield ratio are contradictory properties, and a steel pipe that satisfies both properties has not been obtained by the above method.
第１図は焼入れ処理（ａｓ Ｑ処理）ままとＱ−Ｔ処理
後の鋼管について鋼管外表面から深さ（板厚）方向の硬
さ変化を示したものであり、鋼管の外表面では硬度が高
くなっている。また第１表に示すように一般に高強度鋼
管は高降伏比である。Figure 1 shows the change in hardness in the depth (thickness) direction from the outer surface of the steel pipe for steel pipes as-quenched (as Q-treated) and after Q-T treatment. It's getting expensive. Furthermore, as shown in Table 1, high strength steel pipes generally have a high yield ratio.
第 １ 表
このように従来の高強度鋼管は割れ性、破壊に対する安
全性、良好な敷設性を同時に具備したものではなかった
。Table 1 As described above, conventional high-strength steel pipes have not been able to simultaneously provide crackability, safety against fracture, and good installation performance.
（発明が解決しようとする課題）
本発明はこのような現状に鑑みて、高強度でかつ最高硬
さおよび降伏比の低い鋼管が得られにくい従来のＱ−Ｔ
処理に代わって、強度、溶接性等、その他の特性を損う
ことなく最高硬さおよび降伏比の低い鋼管の製造法を提
供しようとするものである。(Problems to be Solved by the Invention) In view of the current situation, the present invention aims to improve the quality of the conventional Q-T steel pipe, in which it is difficult to obtain a steel pipe with high strength, maximum hardness, and low yield ratio.
The present invention aims to provide a method for producing steel pipes with maximum hardness and low yield ratio without compromising other properties such as strength and weldability.
（課題を解決するための手段）
本発明は、加熱前組織がフェライトとパーライトの混合
組織である゛ような、微視的に炭素濃度の差がある鋼を
Ａ （１変態点＋ｌＯ℃からＡｃ１変態点＋９０℃の温
度に加熱、保定して炭素濃度の高い部分を炭素濃度の低
い部分に先がけてオーステナイト変態をさせ、オーステ
ナイトとフェライトの混合組織を造り、その後急速冷却
することにより、本発明が目的とする鋼管が製造される
ことを知見したもので、その要旨は、常温でフェライト
とパーライトの混合組織を有する鋼をＡ ｃ１変態点＋
１０℃からＡｃ１変態点＋９０℃の温度に加熱、保定後
急速冷却処理を施こすか、あるいはさらにＡ ＣＩ変態
点以下の温度で焼戻し処理することを特徴とする最高硬
さと降伏比の低い高強度鋼管の製造法である。(Means for Solving the Problems) The present invention provides steel with a microscopic difference in carbon concentration such that the structure before heating is a mixed structure of ferrite and pearlite. The present invention is achieved by heating and holding at a temperature of 90° C. above the transformation point to transform the high carbon concentration portion into austenite before the low carbon concentration portion, creating a mixed structure of austenite and ferrite, and then rapid cooling. It was discovered that the desired steel pipe can be manufactured, and the gist is that steel having a mixed structure of ferrite and pearlite at room temperature can be produced at A c1 transformation point +
High strength with maximum hardness and low yield ratio, characterized by heating from 10℃ to Ac1 transformation point + 90℃, followed by rapid cooling treatment, or further tempering treatment at a temperature below ACI transformation point. This is a method of manufacturing steel pipes.
以下本発明について詳細に説明する。The present invention will be explained in detail below.
通常の熱間圧延あるいは高温度に加熱冷却された鋼は特
殊合金鋼（高合金鋼を含む）や強制冷却処理材を除いて
ほとんどフェライトとパーライトの混合組織で、微視的
に炭素濃度差を有した組織である。このような鋼をＡ
（１変態点以上の温度に加熱すると炭素濃度の高い個所
からα→γ変態が優先して起こる。したがってＡ （１
変態以上の適当な温度にて加熱、保定することによりオ
ーステナイトとフェライトの理想的な混合組織を得るこ
とが出来、その後の強制冷却処理によりオーステナイト
が低温変態生成組織に変態して適度の強度を付与するこ
とを知見した。Most steels that have been normally hot-rolled or heated and cooled to high temperatures have a mixed structure of ferrite and pearlite, with the exception of special alloy steels (including high-alloy steels) and forced cooling treated steels, with microscopic differences in carbon concentration. It is an organization with A steel like this
(When heated to a temperature higher than 1 transformation point, α → γ transformation occurs preferentially starting from areas with high carbon concentration. Therefore, A (1
By heating and holding at an appropriate temperature above the transformation temperature, an ideal mixed structure of austenite and ferrite can be obtained, and by subsequent forced cooling treatment, the austenite transforms into a low-temperature transformation-generated structure, imparting appropriate strength. I found out that.
Ａ ＣＩ変態点＋１０℃未満の温度ではオーステナイト
への変態に時間を要することと併せて変態量が少ないこ
とから、強制冷却後に目的とする高強度が得られない。At temperatures below the ACI transformation point +10°C, the desired high strength cannot be obtained after forced cooling because it takes time to transform into austenite and the amount of transformation is small.
またＡｃｌ変態変態点＋９０超Ｃ超度ではオーステナイ
トへの変態量が不必要に増大し、その後の強制冷却で低
温変態生成組織に変態し最高硬さが高くなる。Further, at a temperature exceeding ACl transformation transformation point +90 and above C, the amount of transformation to austenite increases unnecessarily, and the subsequent forced cooling transforms into a low-temperature transformation-generated structure, increasing the maximum hardness.
上記のような温度条件で加熱、保定後強制冷却された鋼
管は硬質層と軟質層が相俟って、強度と加工性の調和し
た、最高硬さと降伏比の低い高強度鋼管となり、製品に
供することが出来る。さらに本発明に従い、急冷によっ
て発生した内部歪の除去と材質レベルの調整のためにＡ
ｃ１変態点以下の低い温度で焼戻し処理を行なう。この
焼戻し処理により硬さ、降伏比、強度がバランス化され
た鋼管を得ることができる。A steel pipe that is heated under the above temperature conditions, held, and then forcedly cooled has a combination of hard and soft layers, resulting in a high-strength steel pipe with a balance of strength and workability, maximum hardness and low yield ratio, and is used as a product. can be provided. Furthermore, according to the present invention, A
Tempering treatment is performed at a low temperature below the c1 transformation point. Through this tempering treatment, a steel pipe with balanced hardness, yield ratio, and strength can be obtained.
本発明によれば、ラインパイプ用鋼管として適当な強度
を有し、最高硬さと降伏比の低い鋼が得られる。According to the present invention, it is possible to obtain a steel having suitable strength as a steel pipe for line pipes, and having a maximum hardness and a low yield ratio.
（実施例） 次に本発明を実施例に基づいて説明する。(Example) Next, the present invention will be explained based on examples.
第２表に示す成分組成の鋼管を供試材とし、熱間圧延後
常温まで自然冷却された鋼管をＡ Ｃ、変態点＋１０℃
からＡ （１変態点＋９０℃の温度に加熱、保定復水中
へ投入し急速冷却で常温まで冷却した。The test material is a steel pipe with the chemical composition shown in Table 2, and the steel pipe that has been naturally cooled to room temperature after hot rolling is A C, transformation point +10°C
A was heated to a temperature of 1 transformation point + 90°C, poured into retained condensate water, and rapidly cooled to room temperature.
さらに前記鋼管を焼戻し処理した時の特性を第３表に示
した。比較法は本発明法と同じ手法にて急速冷却で常温
まで冷却した。さらにＡｃｔ変態以下の任意の温度で焼
戻しを行なった時の鋼の特性を示した。Furthermore, Table 3 shows the characteristics when the steel pipe was tempered. In the comparative method, the sample was rapidly cooled to room temperature using the same method as the method of the present invention. Furthermore, the properties of the steel when tempered at an arbitrary temperature below the Act transformation were shown.
強度特性については本発明による場合通常のＱＴ材に比
べ平均的にや−低めであるが最高硬さ、降伏比共に低い
レベルにある。Regarding the strength properties, the strength properties of the present invention are slightly lower on average than those of ordinary QT materials, but both the maximum hardness and yield ratio are at a low level.
（発明の効果）
このように本発明に従った鋼管の製造法によれｆ、従来
の考え方では達成できなかった、低い最高硬さと低降伏
比特性を同時に得られるものであ〕、産業上碑益すると
ころが極めて大である。(Effects of the Invention) As described above, the steel pipe manufacturing method according to the present invention can simultaneously obtain low maximum hardness and low yield ratio characteristics, which were unachievable using conventional methods. The benefits are extremely large.
第１図は外面焼き入れ処理鋼管（ａｓＱ）と焼戻−鋼管
（ＱＴ）の肉厚方向（外表面からの距Ｍ）つ硬さ変化を
示す図である。FIG. 1 is a diagram showing changes in hardness in the wall thickness direction (distance M from the outer surface) of an externally hardened steel pipe (asQ) and a tempered steel pipe (QT).
Claims (2)
る鋼をＡ＿ｃ＿１変態点＋１０℃からＡ＿ｃ＿１変態点
＋９０℃の温度に加熱、保定後急速冷却処理を施すこと
を特徴とする最高硬さと降伏比の低い高強度鋼管の製造
法。(1) A steel with a mixed structure of ferrite and pearlite at room temperature is heated from the A_c_1 transformation point +10°C to the A_c_1 transformation point +90°C, and then subjected to a rapid cooling treatment after holding.It has a maximum hardness and a low yield ratio. Manufacturing method for high-strength steel pipes.
る鋼をＡ＿ｃ＿１、変態点＋１０℃からＡ＿ｃ＿１変態
点＋９０℃の温度に加熱、保定後低温度に急速冷却した
後、Ａ＿ｃ＿１変態点以下の温度で焼戻し処理すること
を特徴とする最高硬さと降伏比の低い高強度鋼管の製造
法。(2) Steel having a mixed structure of ferrite and pearlite at room temperature is heated from A_c_1, transformation point +10°C to A_c_1 transformation point +90°C, held, rapidly cooled to a low temperature, and then tempered at a temperature below A_c_1 transformation point. A method for manufacturing high-strength steel pipes with maximum hardness and low yield ratio, characterized by
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10144989A JPH02282427A (en) | 1989-04-20 | 1989-04-20 | Manufacture of high strength steel pipe having low maximum hardness and yield ratio |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10144989A JPH02282427A (en) | 1989-04-20 | 1989-04-20 | Manufacture of high strength steel pipe having low maximum hardness and yield ratio |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02282427A true JPH02282427A (en) | 1990-11-20 |
Family
ID=14301001
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10144989A Pending JPH02282427A (en) | 1989-04-20 | 1989-04-20 | Manufacture of high strength steel pipe having low maximum hardness and yield ratio |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02282427A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015019708A1 (en) | 2013-08-06 | 2015-02-12 | 新日鐵住金株式会社 | Seamless steel pipe for line pipe, and method for producing same |
-
1989
- 1989-04-20 JP JP10144989A patent/JPH02282427A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015019708A1 (en) | 2013-08-06 | 2015-02-12 | 新日鐵住金株式会社 | Seamless steel pipe for line pipe, and method for producing same |
| US9651175B2 (en) | 2013-08-06 | 2017-05-16 | Nippon Steel & Sumitomo Metal Corporation | Seamless steel pipe for line pipe |
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