JPS63143222A - Manufacture of steel material having low maximum hardness and low yield ratio - Google Patents
Manufacture of steel material having low maximum hardness and low yield ratioInfo
- Publication number
- JPS63143222A JPS63143222A JP28943986A JP28943986A JPS63143222A JP S63143222 A JPS63143222 A JP S63143222A JP 28943986 A JP28943986 A JP 28943986A JP 28943986 A JP28943986 A JP 28943986A JP S63143222 A JPS63143222 A JP S63143222A
- Authority
- JP
- Japan
- Prior art keywords
- steel material
- steel
- low
- yield ratio
- maximum hardness
- 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 43
- 239000010959 steel Substances 0.000 title claims abstract description 43
- 239000000463 material Substances 0.000 title claims abstract description 26
- 238000004519 manufacturing process Methods 0.000 title claims description 7
- 238000001816 cooling Methods 0.000 claims description 9
- 238000003303 reheating Methods 0.000 claims description 3
- 238000005098 hot rolling Methods 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 abstract description 27
- 238000010791 quenching Methods 0.000 abstract description 6
- 230000000171 quenching effect Effects 0.000 abstract description 6
- 229910001566 austenite Inorganic materials 0.000 abstract description 5
- 230000006866 deterioration Effects 0.000 abstract description 4
- 239000002344 surface layer Substances 0.000 abstract description 3
- 239000010410 layer Substances 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 14
- 238000005496 tempering Methods 0.000 description 11
- 238000011282 treatment Methods 0.000 description 7
- 230000009466 transformation Effects 0.000 description 5
- 229910001111 Fine metal Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000012733 comparative method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000002500 effect on skin Effects 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000000126 substance Substances 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）
本発明は最高硬さおよび降伏比の低い高強度高靭性鋼材
の製造方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, high-toughness steel materials with maximum hardness and low yield ratio.
（従来の技術及び問題点）
近年エネ／ｌ／イー資源の枯渇が問題視されるようにな
り、石油や天然ガスのエネルギー資源の開発に拍車がか
がシ、従来は顧みられなかった悪条件の油井やガス井の
開発が積極的に進められている。これに伴ないこれらの
構造物に使用される鋼管形鋼、厚板などの鋼材にも苛酷
な環境に耐えることが要求されている。すなわち、高強
度高靭性であるばかりでなく、施工性および安全上の見
地から降伏比（引張強度に対する降伏強度の比〕を低く
することが要求されている。また最近開発される油井、
ガス井では硫化水素を含有する場合が多く、したがって
環境脆化防止の見地から材料の最高硬さを低くする規制
が行なわれている。(Conventional technology and problems) In recent years, the depletion of energy/l/e resources has become a problem, and the development of energy resources such as oil and natural gas is gaining momentum, and adverse conditions that were previously ignored The development of oil and gas wells is actively underway. Along with this, steel materials such as steel pipe sections and thick plates used in these structures are also required to withstand harsh environments. In other words, it is required not only to have high strength and high toughness, but also to have a low yield ratio (ratio of yield strength to tensile strength) from the viewpoint of workability and safety.
Gas wells often contain hydrogen sulfide, and therefore, regulations are in place to reduce the maximum hardness of materials from the standpoint of preventing environmental embrittlement.
一般に鋼材の強度と靭性を同時に向上させる方法として
焼入焼戻処理がよく知られている。Generally, quenching and tempering treatment is well known as a method for simultaneously improving the strength and toughness of steel materials.
しかし、ラインパイプ用鋼のような低合金成分の鋼に通
常の焼入焼戻処理を行なった場合、焼入時の冷却速度が
速い表面部の硬度が高く内部の硬度が低くなり、表面と
内面の硬度偏差が大きくなる。すなわち、鋼材の強度と
よく対応する平均硬さに対して最高硬さレベルが高くな
る。However, when regular quenching and tempering is applied to steel with a low alloy content, such as linepipe steel, the hardness is high at the surface where the cooling rate is fast during quenching, and the hardness inside is low. The hardness deviation of the inner surface increases. That is, the maximum hardness level is higher than the average hardness, which corresponds well to the strength of the steel material.
硬さの低い鋼材を製造するためには、表面硬化部を軟化
させる必要があり、高温長時間焼戻処埋が必須である。In order to manufacture steel materials with low hardness, it is necessary to soften the surface hardened portion, and high-temperature and long-term tempering treatment is essential.
一方、降伏比と焼戻温度の調査結果から、５５０℃以上
、Ａｃ１変態点以下の高温度の焼戻処理では強度と降伏
比の間にほぼ一定の関係がちシ、高強度材では降伏比が
高くなることが知られている。したがって高強度材で低
い降伏比を得るためには、低い温度で焼戻を行なう必要
がある。最高硬さと降伏比の低い鋼材を製造するには、
この矛盾を解決しなければならない。この解決策に、特
願昭６０−１２９７０３号のような高周波電流による局
部加熱法がある。On the other hand, the results of the investigation of yield ratio and tempering temperature show that there is a nearly constant relationship between strength and yield ratio in tempering treatments at high temperatures of 550°C or higher and below the Ac1 transformation point, and that in high-strength materials, the yield ratio It is known to increase. Therefore, in order to obtain a low yield ratio with high-strength materials, it is necessary to perform tempering at a low temperature. To produce steel with maximum hardness and low yield ratio,
This contradiction must be resolved. As a solution to this problem, there is a local heating method using high frequency current as disclosed in Japanese Patent Application No. 129703/1983.
これは、高周波電流の表皮効果を活用して、表面硬化部
のみを高温加熱し、内部の温度上昇を抑制する加熱法で
ある。このような加熱法においては鋼材の内部と外部の
温度差を大きくすることが重要であり、熱伝導による均
熱を防止するため、表面部のみを短時間加熱する。しか
しながらＡｃ１変態点温度以下の短時間加熱法では充分
な軟化効果が得られず特に高強度鋼管のように合金元素
を多量に含む場合は焼戻軟化抵抗が大きい、ｔた、焼戻
処理においてＡＣ１変態点を越える高い温度に加熱する
ことは、部分的にオーステナイト組織を生成し、強度お
よび靭性の劣化が著しく大きいことも知られている。This is a heating method that utilizes the skin effect of high-frequency current to heat only the hardened surface area to a high temperature to suppress internal temperature rise. In such a heating method, it is important to increase the temperature difference between the inside and outside of the steel material, and in order to prevent uniform heating due to heat conduction, only the surface portion is heated for a short time. However, short-time heating below the AC1 transformation point temperature does not provide sufficient softening effect, and especially when high-strength steel pipes contain a large amount of alloying elements, the tempering softening resistance is high. It is also known that heating to a high temperature exceeding the transformation point partially produces an austenitic structure, resulting in significant deterioration of strength and toughness.
（問題点を解決するための手段）
このような現状に鑑み、本発明は強度靭性が通常焼入焼
戻鋼なみに維持し、かつ最高硬さと降伏比の低い鋼管の
熱処理方法を探索することを目的に、焼入後の鋼管に対
して広範な熱履歴と金属組織および材質に関する研究を
実施した結果、７５０℃以上の高温に急速加熱を行ない
、ただちに冷却することにより、通常の焼入焼戻処理と
同等の微細な金属組織が維持でき、通常の焼入焼戻処理
よシ低硬度が得られることを知見した。(Means for Solving the Problems) In view of the current situation, the present invention seeks to find a method for heat treatment of steel pipes that maintains the strength and toughness of normal quenched and tempered steel, and has maximum hardness and low yield ratio. With the aim of It was discovered that the same fine metal structure as back treatment can be maintained, and a lower hardness than ordinary quenching and tempering treatment can be obtained.
本発明はこの知見に基づき構成したものであシ、その要
旨は、熱間圧延後あるいは再加熱によシ鋼管を高温から
急冷し、引き続き鋼管の表面硬化層のみを７５０〜８５
０℃の範囲の温度に５℃／秒以上の昇温速度で局部加熱
し、直ちに冷却する最高硬さと降伏比の低い鋼材の製造
方法である。The present invention was constructed based on this knowledge, and its gist is that after hot rolling or reheating, a steel pipe is rapidly cooled from a high temperature, and then only the surface hardened layer of the steel pipe is
This method involves locally heating a steel material to a temperature in the range of 0°C at a heating rate of 5°C/sec or more and cooling immediately, which produces a steel material with maximum hardness and a low yield ratio.
以下本発明について詳細に説明する。第１図は、代表的
なラインノーイブ用銅ｆ（Ｃ：０．０８％。The present invention will be explained in detail below. Figure 1 shows a typical line-neutral copper f (C: 0.08%).
Ｓｔ ：０．１９％、Ｍｎ：１．３０％、Ｐ：０．０２
１％、 Ｓ ： ０．００５％、Ｖ： ０．０４６％、
ＡＡ ： ０．０３０％）を再加熱により９５０℃に
加熱後急冷し、その後引き続いて種々の温度に高周波加
熱法で急速加熱を行ない直ちに冷却した時の最高硬さの
変化を示す。加熱温度７５０℃以下の低い温度では、最
高硬さが通常のＡＣ１変態温度以下の焼戻処理における
硬度レベルとほぼ同等であるが、７５０℃以上に加熱す
ると顕著な最高硬さの低下を示す。しかし、加熱温度が
８５０℃を越え高い温度では硬度が不安定となり、逆に
硬化する。したがって加熱温度は７５０〜８５０℃とす
る。さらに本発明においてはこのような高い温度に速い
昇温速度で加熱し、直ちに冷却することは、重要な要因
である。鋼管を７５０〜８５０℃の温度範囲に通常の除
熱速度で加熱を行なうとオーステナイト変態の進行に伴
い粗大化し九オーステナイトの金属組織に変化し鋼材の
強度および靭性が劣化する。すなわち本発明は５℃／秒
以上の急速加熱し直ちに冷却を開始することによシ、変
態したオーステナイト粒の粗大化を抑制し、通常の焼入
焼戻鋼なみの微細な金属組織を確保して、靭性の劣化と
硬化を防止する。St: 0.19%, Mn: 1.30%, P: 0.02
1%, S: 0.005%, V: 0.046%,
AA: 0.030%) is reheated to 950°C and then rapidly cooled, then rapidly heated to various temperatures by high frequency heating method, and immediately cooled. Changes in maximum hardness are shown. At a low heating temperature of 750° C. or lower, the maximum hardness is almost the same as the hardness level in normal tempering treatment below the AC1 transformation temperature, but when heated to 750° C. or higher, the maximum hardness decreases significantly. However, if the heating temperature exceeds 850° C., the hardness becomes unstable and hardens. Therefore, the heating temperature is 750 to 850°C. Furthermore, in the present invention, it is an important factor to heat to such a high temperature at a fast temperature increase rate and immediately cool it. When a steel pipe is heated to a temperature range of 750 to 850° C. at a normal heat removal rate, the steel pipe becomes coarse as austenite transformation progresses, changes to a nine-austenite metal structure, and the strength and toughness of the steel deteriorate. In other words, the present invention suppresses the coarsening of transformed austenite grains by rapidly heating at 5°C/second or more and immediately starting cooling, thereby ensuring a fine metal structure comparable to that of ordinary quenched and tempered steel. This prevents deterioration of toughness and hardening.
上記のような本発明において高温度から急冷された鋼材
の表面硬化層のみを急速加熱する方法は、高周波電流に
よる誘導加熱、通電加熱、火炎加熱、レーデ光線や電子
ビーム等による加熱法のいかなる加熱手段を用いてもよ
く、その後の冷却も放冷、水冷さらには強冷する任意な
方法で行ってもよい。鋼管分野において本発明にかかわ
る最高硬さと降伏比の低い鋼材の要求が強いので、鋼管
の製造方法として説明してきたが、鋼管に限らず、厚鋼
板、形鋼、条鋼、棒鋼等に対しても有効に適用できるも
のである。In the present invention, the method of rapidly heating only the hardened surface layer of the steel material that has been rapidly cooled from a high temperature can be achieved by any heating method such as induction heating using high-frequency current, current heating, flame heating, Rede beam, electron beam, etc. The subsequent cooling may be carried out by any method such as standing cooling, water cooling, or strong cooling. In the field of steel pipes, there is a strong demand for steel materials with maximum hardness and low yield ratio, which is related to the present invention, so this has been explained as a manufacturing method for steel pipes, but it is also applicable not only to steel pipes but also to thick steel plates, shaped steel, long steel bars, etc. It can be applied effectively.
（実施例） つぎに、本発明の実施例について説明する。(Example) Next, examples of the present invention will be described.
第１表に使用した供試鋼の化学成分を示す。シームレス
圧延で製管し、再加熱法によシ温度９１０℃に加熱し急
冷する焼入処理を行なった鋼管に対し、誘導加熱法で各
種の焼戻を実施して材質試験を行なった。焼戻条件と材
質特性の比較を第２表に示す。Table 1 shows the chemical composition of the test steel used. Steel pipes were made by seamless rolling, then quenched by heating to a temperature of 910°C by a reheating method and then rapidly cooled, and various types of tempering were performed by an induction heating method to conduct material tests. Table 2 shows a comparison of tempering conditions and material properties.
本発明法では強度が平均的に高めであるＫもかかわらず
、降伏比のレベルは低い。低い降伏比と併せて、最高硬
さも低いレベルに制御されている。また、靭性レベルも
強度・靭性ノ々ランスでみるかぎシ、比較法に比べ遜色
がない。昇温速度が遅い場合、あるいは７５０〜８５０
℃の温度で保定した場合は、靭性の劣化と著しい強度低
下が認められる。また、加熱温度が高過ぎる場合は、加
熱後の急冷により最高硬さが高くなっている。In the method of the present invention, although the strength is on average higher than K, the level of yield ratio is low. In addition to the low yield ratio, the maximum hardness is also controlled to a low level. In addition, the toughness level is comparable to the comparative method in terms of strength and toughness. If the heating rate is slow, or 750-850
When kept at a temperature of ℃, deterioration of toughness and significant decrease in strength are observed. Moreover, when the heating temperature is too high, the maximum hardness becomes high due to rapid cooling after heating.
（発明の効果）
以上説明した如く本発明の製造法は、高強度鋼材の最高
硬さ制御と低降伏比化を可能とする製造法であり、産業
上袢益するところ極めて大である。(Effects of the Invention) As explained above, the manufacturing method of the present invention is a manufacturing method that makes it possible to control the maximum hardness and lower the yield ratio of high-strength steel materials, and has extremely large industrial benefits.
第１図は、焼入処理に引き続き急速加熱を行ない直ちに
冷却した時の、加熱温、度と鋼材の最高硬さの関係を示
す図である。
第１図
力口＃［！ＪＬ＆FIG. 1 is a diagram showing the relationship between heating temperature, degree, and maximum hardness of a steel material when rapid heating is performed subsequent to quenching treatment and immediately cooled. Figure 1 Power mouth #[! JL&
Claims (1)
し、引き続き鋼材の表面硬化層のみを７５０〜８５０℃
の範囲の温度に５℃／秒以上の昇温速度で局部加熱し、
直ちに冷却することを特徴とする最高硬さと降伏比の低
い鋼材の製造方法。After hot rolling or reheating, the steel pipe is rapidly cooled from a high temperature, and then only the surface hardened layer of the steel material is heated to 750 to 850°C.
Locally heated to a temperature in the range of 5℃/second or more,
A method for producing steel materials with maximum hardness and low yield ratio, characterized by immediate cooling.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28943986A JPS63143222A (en) | 1986-12-04 | 1986-12-04 | Manufacture of steel material having low maximum hardness and low yield ratio |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28943986A JPS63143222A (en) | 1986-12-04 | 1986-12-04 | Manufacture of steel material having low maximum hardness and low yield ratio |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63143222A true JPS63143222A (en) | 1988-06-15 |
Family
ID=17743270
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28943986A Pending JPS63143222A (en) | 1986-12-04 | 1986-12-04 | Manufacture of steel material having low maximum hardness and low yield ratio |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63143222A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004346355A (en) * | 2003-05-21 | 2004-12-09 | Jfe Steel Kk | Method for producing electroseamed steel pipe for high-strength line pipe excellent in hydrogen-crack resistance |
| 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 |
| JP2022070602A (en) * | 2020-10-27 | 2022-05-13 | トヨタ自動車株式会社 | Method and apparatus for manufacturing steel product |
-
1986
- 1986-12-04 JP JP28943986A patent/JPS63143222A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2004346355A (en) * | 2003-05-21 | 2004-12-09 | Jfe Steel Kk | Method for producing electroseamed steel pipe for high-strength line pipe excellent in hydrogen-crack resistance |
| 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 |
| JP2022070602A (en) * | 2020-10-27 | 2022-05-13 | トヨタ自動車株式会社 | Method and apparatus for manufacturing steel product |
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