JPH027368B2 - - Google Patents
Info
- Publication number
- JPH027368B2 JPH027368B2 JP5962184A JP5962184A JPH027368B2 JP H027368 B2 JPH027368 B2 JP H027368B2 JP 5962184 A JP5962184 A JP 5962184A JP 5962184 A JP5962184 A JP 5962184A JP H027368 B2 JPH027368 B2 JP H027368B2
- Authority
- JP
- Japan
- Prior art keywords
- rolling
- present
- sec
- cooled
- less
- 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
- 229910000831 Steel Inorganic materials 0.000 claims description 28
- 239000010959 steel Substances 0.000 claims description 28
- 238000001816 cooling Methods 0.000 claims description 26
- 238000005096 rolling process Methods 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 230000009466 transformation Effects 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims 4
- 239000012535 impurity Substances 0.000 claims 2
- 229910052742 iron Inorganic materials 0.000 claims 2
- 229910052748 manganese Inorganic materials 0.000 claims 2
- 229910052758 niobium Inorganic materials 0.000 claims 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 229910001566 austenite Inorganic materials 0.000 description 8
- 229910001563 bainite Inorganic materials 0.000 description 8
- 230000000694 effects Effects 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 238000005496 tempering Methods 0.000 description 7
- 238000011084 recovery Methods 0.000 description 4
- 238000001953 recrystallisation Methods 0.000 description 4
- 238000007796 conventional method Methods 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 229910000746 Structural steel Inorganic materials 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 238000012733 comparative method Methods 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000003129 oil well Substances 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910000859 α-Fe Inorganic materials 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
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (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 Steel (AREA)
Description
（産業上の利用分野）
本発明は油井用鋼管あるいは構造用鋼管等に使
用される強靭鋼管の製造方法に関するものであ
る。
（従来技術）
高強度で靭性の高いことが必要な油井用鋼管あ
るいは構造用鋼管は従来最終的に焼準、焼準−焼
戻し、あるいは焼入れ−焼戻しの熱処理が施され
るのが普通である。
上記のような熱処理を施さない強靭鋼管の製造
方法として特公昭57−9408号公報記載の方法が公
知であり、この方法はA1変態点以上でA3変態点
以下の温度に再加熱しストレツチレヂユーサーミ
ルで圧下率40％以上の加工を加え、その後A1変
態点以下の温度で焼戻し処理をすることからな
る。
しかしながらこの方法は加熱温度が低いため必
然的に変形抵抗が高く、又圧延が二相域にかかる
ことから変形抵抗が著しく変化しそのため圧延に
おいて所望の寸法精度を得ることが困難であるば
かりでなく、加工されたフエライトの回復、再結
晶をさせるための焼戻し処理が必須であるという
難点がある。
（発明の目的）
本発明は熱間圧延は完全オーステナイト域で行
い、熱間圧延のままで従来の製造法による鋼管に
優る靭性を有する鋼管を製造する方法を提供する
目的でなされたものである。
（発明の構成）
以下本発明を詳細に説明する。
熱間圧延ままで高強度を得るにはベイナイト組
織となすことが有効であり、これは適切な化学成
分の添加と圧延後の冷却速度を制御することによ
り達成される。本発明により製造される鋼管の鋼
成分は熱間加工後空冷もしくは水冷で均一なベイ
ナイト組織となる範囲としている。又本発明にお
いては圧延が完全オーステナイト域で終るように
適正な加熱温度範囲を定めた。
圧延ままで高靭性を得るにはある量以上の加工
をオーステナイトに与える必要があることは公知
である。本発明者はストレツチレヂユーサーミル
圧延におけるオーステナイトの回復、再結晶挙動
を研究した結果、ストレツチレヂユーサーミル圧
延において圧延温度が1150℃以下の場合パス間時
間が0.5秒以下であればオーステナイトの回復、
再結晶が生じないことを明らかにした。それ故
1150℃以下の圧延温度でパス間時間が0.5秒以下
の圧延速度のストレツチレヂユーサーミルによる
圧延を行えばストレツチレヂユーサーミルの合計
圧延量が有効な加工量として作用することを見出
した。この条件における高靭化に必要な加工量の
最低限度は20％である。
すなわち本発明は完全オーステナイト域で高靭
化に有効な加工量を与える圧延条件とそれが圧延
後均一なベイナイト組織となる条件を組み合せた
ことを骨子とする強靭鋼管の製造方法である。
次に本発明により製造される鋼管の鋼成分の限
定理由について述べる。以下％はいずれもwt％
である。
Ｃは0.30％超では靭性が劣化するため、0.30％
以下とした。
Siは脱酸あるいは強度調整用として添加するも
ので、0.10％以下では脱酸不足であり、１％以上
では脆化が生ずるので、0.1〜1.0％とした。
Mnはベイナイト組織となすため1.0％以上必要
であり、3.0％超ではマルテンサイト組織となり
脆化するので1.0〜3.0％とした。
Alは脱酸のため必要な量だけ添加するもので、
その添加量は0.005〜0.10％である。
Nbは細粒化およびベイナイト組織となすため
添加するもので0.01％以上必であり、又0.15％を
超える添加は効果の向上がないため0.01％〜0.15
％とした。
Ｂ、Cr、Mo、Ni、Cuはベイナイト生成作用
に有効な範囲で添加するものであり、又、Ti、
Ｖは細粒化に有効な範囲で添加するもので、
夫々、Ｂ：0.0007〜0.002％、Cr：0.10〜1.00％、
Mo：0.10〜0.50％、Ni：0.10〜2.0％、Cu：0.10
〜1.0％、Ti：0.01〜0.10％、Ｖ：0.01〜0.10％の
１種又は２種以上を添加する。
加熱温度の限定理由は次の通りである。即ち、
完全オーステナイト域の圧延を確保するためAc3
＋50℃以上とし、又オーステナイトの粗大化防止
と圧延中の回復、再結晶を生じさせないため、
1150℃以下とした。
又、パス間におけるオーステナイトの回復、再
結晶を防止するためおよび圧延を完全オーステナ
イト域で終らさせるため、パス間時間を0.5秒以
下とした。
圧延後の冷却の空冷あるいは水冷の選択は空冷
によつてベイナイト組織とならない合金量の少い
鋼については水冷を行うことが必須であり、空冷
によつてベイナイト組織となる鋼については必須
ではないがさらに強度を上げる必要のあるときに
は水冷を行う。
水冷する場合、冷却速度が５℃／sec未満では
空冷との差がなく無意味であり、60℃／secを超
えると焼きが入りマルテンサイト組織となり脆化
するので冷却速度を５〜60℃／secと定めた。
冷却温度が500℃以上で水冷を止めるのは均一
ベイナイトにする効果がないので、少くとも500
℃まで冷却するものである。（勿論500℃以下であ
れば上記効果を達成することができる。）
なお、本発明の工程のあと、更にA1変態点以
下の温度で焼戻し処理を施してもよい。即ち、焼
戻し処理は製品の引張強さを下げ、耐力を向上す
る効果があるので、目的に応じて適宜採用してよ
い。
（実施例）
次に本発明の実施例について説明する。
第１表は本発明による鋼管と比較法および従来
法による鋼管とを比較したものである。
本発明鋼管はＡ、Ｆ、Ｋ、Ｎ、Ｏ、Ｐであり、
比較法による鋼管は＊印のＢ、Ｃ、Ｄ、Ｅ、Ｈ、
Ｉ、Ｊ、Ｌ、Ｍであり、従来法はQ**である。
B*は本発明の加熱温度の範囲外であるAc3＋50
℃以下の温度に加熱したものであり、C*はパス
間時間が本発明より長く、D*は加熱温度が本発
明より高く、またE*は本発明の圧下量より少な
いものであり、いずれも本発明の鋼管より劣悪な
靭性値を示している。H*は水冷による冷却速度
が本発明より遅いものであり、本発明鋼Ａと比較
するとほぼ同程度の性質を示して居り、水冷した
価値がないことを示す。I*は水冷を本発明の冷却
停止温度以上で止めたもので本発明のＡと比較す
れば同じ程度の材質であり水冷の効果がないこと
を示す。J*は本発明の水冷冷却速度を超えるもの
で強度は出るが靭性は劣悪である。L*はＣが本
発明の範囲外強度は出るが靭性劣悪である。M*
はMnが本発明の範囲外水冷を行つても強度が出
ない。
Ｎ、Ｏ、Ｐは附加的にＢ、Ni、Cu、Cr、Mo、
Ｖ、Tiを添加した例であるが本発明の特徴を損
わず強度上昇、靭性向上、Mn量減少に有効であ
ることを示している。Ｋは本発明鋼に焼戻しを施
した例で引張り強さの低下、耐力の上昇に焼戻し
が有効であることを示す。
Q**は従来法である焼入、焼戻しした鋼管であ
るが、本発明鋼管は優るとも劣らない材質を示し
ている。
（発明の効果）
以上、詳述したように、本発明によつて製造さ
れる鋼管は熱間圧延ままで従来の熱処理したもの
と同等又は同等以上の優れた靭性をもつものであ
るから、省工程による工業的効果は極めて顕著で
ある。
(Industrial Application Field) The present invention relates to a method for manufacturing strong steel pipes used as oil well steel pipes, structural steel pipes, and the like. (Prior Art) Steel pipes for oil wells or structural steel pipes that require high strength and high toughness are usually finally subjected to heat treatment of normalizing, normalizing-tempering, or quenching-tempering. The method described in Japanese Patent Publication No. 57-9408 is known as a method for producing strong steel pipes without heat treatment as described above, and this method involves reheating to a temperature above A1 transformation point and below A3 transformation point and stress It consists of processing with a Tsuchirejiyu Thermill at a reduction rate of 40% or more, and then tempering at a temperature below the A1 transformation point. However, since this method uses a low heating temperature, the deformation resistance is inevitably high, and since the rolling is carried out in a two-phase region, the deformation resistance changes significantly, making it difficult to obtain the desired dimensional accuracy in rolling. However, there is a drawback in that a tempering treatment is essential to recover and recrystallize the processed ferrite. (Purpose of the Invention) The present invention has been made for the purpose of providing a method for manufacturing a steel pipe that is hot rolled in a completely austenitic region and has toughness superior to steel pipes manufactured by conventional manufacturing methods without changing the hot rolling process. . (Structure of the Invention) The present invention will be described in detail below. In order to obtain high strength as hot-rolled, it is effective to form a bainite structure, and this is achieved by adding appropriate chemical components and controlling the cooling rate after rolling. The steel composition of the steel pipe manufactured according to the present invention is set in a range where a uniform bainite structure can be obtained by air cooling or water cooling after hot working. Further, in the present invention, an appropriate heating temperature range is determined so that rolling ends in a completely austenitic region. It is known that in order to obtain high toughness in as-rolled austenite, it is necessary to subject austenite to a certain amount of processing. As a result of research on the recovery and recrystallization behavior of austenite in stretch-reduced thermal mill rolling, the present inventor found that in stretch-reduced thermal mill rolling, when the rolling temperature is 1150°C or lower and the interpass time is 0.5 seconds or less, austenite recovery,
It was revealed that no recrystallization occurred. Therefore
It has been found that if rolling is performed with a stretch-reducer thermill at a rolling temperature of 1150°C or lower and a rolling speed with an interpass time of 0.5 seconds or less, the total rolling amount of the stretch-reducer thermill acts as an effective working amount. The minimum amount of processing required to increase toughness under these conditions is 20%. That is, the present invention is a method for manufacturing a strong steel pipe, which is based on a combination of rolling conditions that provide a working amount effective for increasing toughness in the fully austenite region, and conditions that result in a uniform bainite structure after rolling. Next, the reason for limiting the steel composition of the steel pipe manufactured by the present invention will be described. All percentages below are wt%
It is. If C exceeds 0.30%, the toughness deteriorates, so 0.30%
The following was made. Si is added for deoxidation or strength adjustment, and if it is less than 0.10%, deoxidation is insufficient, and if it is more than 1%, embrittlement occurs, so it is set at 0.1 to 1.0%. Mn is required to be 1.0% or more to form a bainite structure, and if it exceeds 3.0%, it becomes a martensitic structure and becomes brittle, so it is set at 1.0 to 3.0%. Al is added only in the necessary amount for deoxidation.
The amount added is 0.005-0.10%. Nb is added to refine grains and form a bainite structure, and must be at least 0.01%.Additionally, addition of more than 0.15% will not improve the effect, so 0.01% to 0.15% is required.
%. B, Cr, Mo, Ni, and Cu are added within an effective range for bainite generation, and Ti,
V is added within an effective range for grain refinement.
B: 0.0007-0.002%, Cr: 0.10-1.00%, respectively.
Mo: 0.10~0.50%, Ni: 0.10~2.0%, Cu: 0.10
-1.0%, Ti: 0.01-0.10%, V: 0.01-0.10%, or one or more of them are added. The reason for limiting the heating temperature is as follows. That is,
Ac 3 to ensure rolling in the fully austenitic region
+50℃ or higher, and to prevent austenite from coarsening and to prevent recovery and recrystallization during rolling.
The temperature was set to 1150℃ or less. Furthermore, in order to prevent recovery and recrystallization of austenite between passes and to finish rolling in a completely austenite region, the interpass time was set to 0.5 seconds or less. Regarding the selection of air cooling or water cooling for cooling after rolling, water cooling is essential for steels with a small amount of alloy that do not form a bainitic structure by air cooling, but is not essential for steels that form a bainite structure by air cooling. When it is necessary to further increase strength, water cooling is used. When using water cooling, if the cooling rate is less than 5°C/sec, it is meaningless as there is no difference from air cooling, and if it exceeds 60°C/sec, it will harden and become martensitic structure and become brittle, so the cooling rate should be set to 5 to 60°C/sec. sec. Stopping water cooling when the cooling temperature is over 500℃ has no effect on uniform bainite, so at least 500℃
It is used to cool down to ℃. (Of course, the above effect can be achieved as long as the temperature is 500°C or lower.) After the process of the present invention, a tempering treatment may be further performed at a temperature lower than the A1 transformation point. That is, since the tempering treatment has the effect of lowering the tensile strength of the product and improving the yield strength, it may be employed as appropriate depending on the purpose. (Example) Next, an example of the present invention will be described. Table 1 compares the steel pipe according to the present invention with steel pipes according to the comparative method and the conventional method. The steel pipes of the present invention are A, F, K, N, O, P,
Steel pipes made by the comparative method are B, C, D, E, H, marked with *.
I, J, L, M, and the conventional method is Q ** . B * is outside the heating temperature range of the present invention Ac 3 +50
℃ or less, C * has a longer interpass time than the present invention, D * has a heating temperature higher than the present invention, and E * has a lower rolling reduction than the present invention. The steel pipe also shows a toughness value inferior to that of the steel pipe of the present invention. The cooling rate of H * by water cooling is slower than that of the present invention, and when compared with Invention Steel A, it exhibits almost the same properties, indicating that water cooling is not worth it. I * indicates that water cooling is stopped at a temperature higher than the cooling stop temperature of the present invention, and when compared with A of the present invention, the material is of the same level, indicating that water cooling has no effect. J * exceeds the water-cooling rate of the present invention, resulting in strength but poor toughness. For L * , C has strength outside the range of the present invention, but has poor toughness. M *
In this case, strength is not obtained even if water cooling is performed when Mn is outside the range of the present invention. N, O, P are additionally B, Ni, Cu, Cr, Mo,
Although this is an example in which V and Ti are added, it is shown that they are effective in increasing strength, improving toughness, and reducing the amount of Mn without impairing the characteristics of the present invention. K is an example in which the steel of the present invention was tempered, and indicates that tempering is effective in reducing tensile strength and increasing yield strength. Q ** is a steel pipe that has been quenched and tempered using the conventional method, but the steel pipe of the present invention exhibits superior material quality. (Effects of the Invention) As detailed above, the steel pipe manufactured by the present invention has excellent toughness equivalent to or higher than that of the conventional heat-treated steel pipe as hot-rolled. The industrial effects of the process are extremely significant.
【表】【table】
Claims (1)
％、Al：0.005〜0.10％、Nb：0.01〜0.15％を含
有し残部が鉄および不可避不純物よりなる鋼の母
管をAc3変態点＋50℃以上1150℃以下に加熱し、
パス間時間が0.5秒以下の圧延速度のストレツチ
レヂユーサーミルにより圧下率20％以上で圧延
し、圧延後空冷もしくは５℃／sec〜60℃／secの
冷却速度で少なくとも500℃まで水冷することを
特徴とする強靭鋼管の製造方法。 ２ Ｃ≦0.30％、Si：0.1〜1.0％、Mn：1.0〜3.0
％、Al：0.005〜0.10％、Nb：0.01〜0.15％を含
有し、さらにＢ：0.0007〜0.002％、Cr：0.10〜
1.00％、Mo：0.10〜0.50％、Ni：0.10〜2.0％、
Cu：0.10〜1.0％、Ti：0.01〜0.10％、Ｖ：0.01〜
0.10％、の１種又は２種以上を含有し残部が鉄お
よび不可避不純物よりなる鋼の母管をAc3変態点
＋50℃以上1150℃以下に加熱し、パス間時間が
0.5秒以下の圧延速度のストレツチレヂユーサー
ミルにより圧下率20％以上で圧延し、圧延後空冷
もしくは５℃／sec〜60℃／secの冷却速度で少な
くとも500℃まで水冷することを特徴とする強靭
鋼管の製造方法。[Claims] 1 C≦0.30%, Si: 0.1 to 1.0%, Mn: 1.0 to 3.0
%, Al: 0.005 to 0.10%, Nb: 0.01 to 0.15%, with the balance consisting of iron and unavoidable impurities, heated to Ac 3 transformation point + 50 ° C or more and 1150 ° C or less,
Rolled at a reduction rate of 20% or more using a stretch reduction thermomill with a rolling speed of 0.5 seconds or less between passes, and air-cooled after rolling or water-cooled to at least 500°C at a cooling rate of 5°C/sec to 60°C/sec. A method for producing strong steel pipes characterized by: 2 C≦0.30%, Si: 0.1-1.0%, Mn: 1.0-3.0
%, Al: 0.005~0.10%, Nb: 0.01~0.15%, further B: 0.0007~0.002%, Cr: 0.10~
1.00%, Mo: 0.10~0.50%, Ni: 0.10~2.0%,
Cu: 0.10~1.0%, Ti: 0.01~0.10%, V: 0.01~
A steel mother pipe containing one or more of 0.10% and the remainder consisting of iron and unavoidable impurities is heated to a temperature above Ac 3 transformation point + 50°C and below 1150°C, and the interpass time is
It is characterized by being rolled at a reduction rate of 20% or more using a stretch reduction thermomill with a rolling speed of 0.5 seconds or less, and then air-cooled after rolling or water-cooled to at least 500°C at a cooling rate of 5°C/sec to 60°C/sec. A method for manufacturing strong steel pipes.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5962184A JPS60204829A (en) | 1984-03-29 | 1984-03-29 | Manufacture of tough and hard steel pipe |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5962184A JPS60204829A (en) | 1984-03-29 | 1984-03-29 | Manufacture of tough and hard steel pipe |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60204829A JPS60204829A (en) | 1985-10-16 |
| JPH027368B2 true JPH027368B2 (en) | 1990-02-16 |
Family
ID=13118493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP5962184A Granted JPS60204829A (en) | 1984-03-29 | 1984-03-29 | Manufacture of tough and hard steel pipe |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60204829A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63250418A (en) * | 1987-04-07 | 1988-10-18 | Nippon Steel Corp | Manufacture of line pipe combining high strength with low yield ratio |
| JP2578599B2 (en) * | 1987-04-08 | 1997-02-05 | 新日本製鐵株式会社 | Manufacturing method of low yield ratio steel with excellent sulfide stress corrosion cracking resistance |
-
1984
- 1984-03-29 JP JP5962184A patent/JPS60204829A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60204829A (en) | 1985-10-16 |
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