JPH04168217A - Manufacture of high toughness and high tensile strength hot rolled steel sheet excellent in uniformity - Google Patents
Manufacture of high toughness and high tensile strength hot rolled steel sheet excellent in uniformityInfo
- Publication number
- JPH04168217A JPH04168217A JP29216790A JP29216790A JPH04168217A JP H04168217 A JPH04168217 A JP H04168217A JP 29216790 A JP29216790 A JP 29216790A JP 29216790 A JP29216790 A JP 29216790A JP H04168217 A JPH04168217 A JP H04168217A
- Authority
- JP
- Japan
- Prior art keywords
- less
- rolling
- toughness
- temperature
- hot
- 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
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 25
- 239000010959 steel Substances 0.000 title claims abstract description 25
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000005096 rolling process Methods 0.000 claims abstract description 102
- 238000005098 hot rolling Methods 0.000 claims abstract description 16
- 238000001816 cooling Methods 0.000 claims abstract description 15
- 238000004804 winding Methods 0.000 claims description 23
- 239000000463 material Substances 0.000 claims description 22
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 229920006395 saturated elastomer Polymers 0.000 description 5
- 239000010949 copper Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 238000011835 investigation Methods 0.000 description 3
- 229910052698 phosphorus Inorganic materials 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000002436 steel type Substances 0.000 description 3
- 229910052717 sulfur Inorganic materials 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- 230000032683 aging Effects 0.000 description 2
- 229910052796 boron Inorganic materials 0.000 description 2
- 229910052804 chromium Inorganic materials 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 239000006104 solid solution Substances 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000003679 aging effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
(産業上の利用分野)
この発明は、靭性、引張特性など均一性に優れる高靭性
・高張力熱延鋼板の製造方法に関するもので、特にライ
ンパイプ、構造物等に使用する低温用鋼板の製造方法と
して有用である。[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for manufacturing a high-toughness, high-tensile strength hot-rolled steel sheet that has excellent uniformity in terms of toughness and tensile properties, and is particularly applicable to line pipes, structures, etc. This method is useful as a method for producing low-temperature steel plates.
(従来の技術)
従来、ラインパイプ、構造物等の用途に使用する高靭性
・高張力熱延鋼板の製造方法としては、例えば、特公昭
58−19724号公報に開示されているように、Nb
を添加した鋼を制御圧延して高靭性を得ると同時に、低
P化による耐セパレーシヨン性能の向上を得ようとする
方法や、特開昭61−34116号公報に開示されてい
るように、上記に加え、Ti添加と低い巻取り温度によ
り、歪時効による劣化をも防止し、高靭性を得ようとす
る方法がある。(Prior Art) Conventionally, as a method for manufacturing high toughness/high tensile strength hot rolled steel sheets used for line pipes, structures, etc., for example, as disclosed in Japanese Patent Publication No. 58-19724, Nb
As disclosed in Japanese Patent Application Laid-open No. 61-34116, a method is disclosed in which high toughness is obtained by controlled rolling of steel added with P, and at the same time, separation resistance is improved by lowering P. In addition to the above, there is a method of preventing deterioration due to strain aging and obtaining high toughness by adding Ti and low winding temperature.
これらは、Nb含有鋼の制御圧延を基本としているため
、オーステナイト低温域での圧下率のコントロールと低
い圧延終了温度を必要としている。Since these are based on controlled rolling of Nb-containing steel, they require control of the rolling reduction in the austenite low temperature range and a low rolling end temperature.
これは制御の難しい圧延であり、適性な成分で、適性な
圧延を実施しても、同一コイル内において、圧延先端側
から後端側にかけての温度低下や、圧延先後端での局部
的温度低下などがあり、コイル長手方向に圧延温度が異
なるため、材質特性の均一性に劣り、単一コイル内で所
定の特性が得られない部分が生じ、製品の歩留りを悪く
する場合が多い。This is a rolling process that is difficult to control, and even if proper rolling is performed with appropriate ingredients, there may be a temperature drop from the rolling tip to the rolling end or a local temperature drop at the rolling tip or rear end within the same coil. Because the rolling temperature differs in the longitudinal direction of the coil, the uniformity of material properties is poor, and there are parts in a single coil where predetermined properties cannot be obtained, which often results in poor product yield.
また、上記温度差を減少する方法としての、圧延速度を
上げる所謂ズーミングアップは、圧延時のロールと鋼板
表面との間の摩擦抵抗の変動が大きくなり、板の長手方
向及び板厚方向の圧延歪が一定でなくなり、均一な特性
が得られなくなるなどの問題がある。In addition, so-called zooming up, which increases the rolling speed as a method of reducing the temperature difference, increases the variation in frictional resistance between the rolls and the surface of the steel sheet during rolling, and reduces rolling in the longitudinal direction and thickness direction of the sheet. There are problems such as distortion becoming inconsistent and uniform characteristics not being obtained.
(発明が解決しようとする課B)
この発明は、熱間圧延の仕上げ圧延で制御圧延を行うに
際し、被圧延材の温度の均一化を計ることにより、均一
性に優れる高靭性・高張力熱延鋼板を製造することにあ
る。(Problem B to be Solved by the Invention) This invention provides high-toughness and high-tensile heat with excellent uniformity by uniformizing the temperature of the rolled material when performing controlled rolling in finish rolling of hot rolling. The purpose is to manufacture rolled steel plates.
(課題を解決するための手段)
この発明は、高靭性・高張力の得られる成分組成の鋼片
素材の熱間圧延を、被圧延材の粗圧延における圧延先後
端を仕上げ圧延において逆転させ、かつ、被圧延を順次
接続し、制御圧延を行なうことにより、被圧延材全長に
わたる圧延温度の均一化をはかり、均一性に優れる熱延
板を製造しようとするもので、
その要旨は、次の通りである。(Means for Solving the Problems) This invention involves hot rolling of a steel billet material having a chemical composition that provides high toughness and high tensile strength, by reversing the rolling tip and trailing end in rough rolling of the material to be rolled in finish rolling. In addition, by sequentially connecting the rolled parts and performing controlled rolling, the rolling temperature is made uniform over the entire length of the rolled material, and hot-rolled sheets with excellent uniformity are manufactured. That's right.
1、 C: 0.01wt%以上、0.3讐t%以下
Si : 0.5wt%以下
Mn : 0.5wt%以上、2.0wt%以下5ol
A1 : 0.01wt%以上、0.10wt%以下P
: 0.025wt%以下
S : 0.010wt%以下、及び、N : 0.0
050wt%以下、
を含み、かつ
Ti=0.005wt%以上、0.100wt%以下、
及びNb・・・0.005%1t%以上、0.100w
t%以下、のうちから選んだ1種又は2種を含有し、残
部は鉄及び不可避不純物の組成になる連続鋳造鋼片素材
を熱間圧延する際、
粗圧延段階を経たシートバーを一旦コイル状に巻き取り
、その後、巻き終り端から仕上げ圧延を、950℃以下
での圧下率が50%以上で、圧延終了温度が700℃以
上、800℃以下の範囲にて開始し、その後端に、後続
するシートバーコイルの巻き終り端を接続して、仕上げ
圧延を連続的に行ない、この仕上げ圧延に続いて、5℃
/S以上の冷却速度で2、冷し、450℃以上、600
℃以下の温度範囲で巻取ることを特徴とする均一性に優
れる高靭性・高張力熱延鋼板の製造方法。1. C: 0.01 wt% or more, 0.3 wt% or less Si: 0.5 wt% or less Mn: 0.5 wt% or more, 2.0 wt% or less
A1: 0.01wt% or more, 0.10wt% or less P
: 0.025wt% or less S: 0.010wt% or less and N: 0.0
050 wt% or less, and Ti = 0.005 wt% or more and 0.100 wt% or less,
and Nb...0.005%1t% or more, 0.100w
When hot rolling a continuous cast billet material containing one or two selected from t% or less, with the remainder consisting of iron and unavoidable impurities, the sheet bar that has gone through the rough rolling stage is once rolled into a coil. After that, finish rolling is started from the end of the winding at a rolling reduction rate of 50% or more at 950°C or less and a rolling end temperature of 700°C or more and 800°C or less, and at the rear end, The winding end of the succeeding sheet bar coil is connected and finish rolling is performed continuously.Following this finish rolling,
2, cooling at a cooling rate of /S or more, 450°C or more, 600
A method for producing a high-toughness, high-tensile strength hot-rolled steel sheet with excellent uniformity, which is characterized by winding at a temperature range below ℃.
2、 C: 0.01wt%以上、0.3wt%以下
St : 0.5wt%以下
Mn : 0.5wt%以上、2.0wt%以下5ol
A1 : 0.01wt%以上、0.10御t%以下P
: 0.025wt%以下
S : 0.010wt%以下、及び、N : 0.0
050wt%以下、
と、
Ti・・・0.005wt%以上、0.100wt%以
下、及びNb・・・0.005御t%以上、0.100
wt%以下、のうちから選んだ1種又は2種を含み、か
つCr : 0.5wt%以下、
Ni : 0.5wt%以下、
Mo : 0.3wt%以下、
V : 0.15wt%以下、
B : 0.0050wt%以下、
Cu : 0.50wt%以下、
Ca : 0.010wt%以下、及ヒREM : 0
.010wt%以下、
のうちから選んだ1種又は2種以上を含有し、残部は鉄
及び不可避不純物の組成になる連続鋳造鋼片素材を熱間
圧延する際、
粗圧延段階を経たシートバーを一旦コイル状に巻き取り
、その後、巻き終り端から仕上げ圧延を、950℃以下
での圧下率が50%以上で、圧延終了温度が700℃以
上、800℃以下の範囲にて開始し、その後端に、後続
するシートバーコイルの巻き終り端を接続して、仕上げ
圧延を連続的に行ない、この仕上げ圧延に続いて、5°
c/3以上の冷却速度で急冷し、450℃以上、600
℃以下の温度範囲で巻取ることを特徴とする均一性に優
れる高靭性・高張力熱延鋼板の製造方法。2. C: 0.01 wt% or more, 0.3 wt% or less St: 0.5 wt% or less Mn: 0.5 wt% or more, 2.0 wt% or less 5ol
A1: 0.01 wt% or more, 0.10 wt% or less P
: 0.025wt% or less S: 0.010wt% or less and N: 0.0
050 wt% or less, Ti...0.005 wt% or more, 0.100 wt% or less, and Nb...0.005 wt% or more, 0.100
wt% or less, and Cr: 0.5wt% or less, Ni: 0.5wt% or less, Mo: 0.3wt% or less, V: 0.15wt% or less, B: 0.0050wt% or less, Cu: 0.50wt% or less, Ca: 0.010wt% or less, and REM: 0
.. When hot rolling a continuous cast billet material containing one or more selected from the following at 0.10 wt% or less, with the remainder being iron and unavoidable impurities, the sheet bar that has undergone the rough rolling stage is It is wound into a coil shape, and then finish rolling is started from the end of the winding at a rolling reduction rate of 50% or more at 950°C or less and a rolling end temperature of 700°C or more and 800°C or less. , the winding ends of the following sheet bar coils are connected, finish rolling is performed continuously, and following this finish rolling, 5°
Rapid cooling at a cooling rate of c/3 or higher, 450℃ or higher, 600℃
A method for producing a high-toughness, high-tensile strength hot-rolled steel sheet with excellent uniformity, which is characterized by winding at a temperature range below ℃.
ここに、シートバーの接続方法は、アップセット溶接、
高周波加熱溶接などを用いてよく、特に限定するもので
はない。Here, the seat bar connection method is upset welding,
High frequency heating welding or the like may be used, and there is no particular limitation.
(作 用)
まず、この発明における成分組成の限定理由について述
べる。(Function) First, the reason for limiting the component composition in this invention will be described.
C:強度を向上するための成分で、強度向上のためには
0.01wt%以上含有することが必要である。C: A component for improving strength, and must be contained in an amount of 0.01 wt% or more in order to improve strength.
しかし、0 、30w t%を超えると溶接性や低温靭
性が劣化する。したがって、その含有量は0.01wt
%以上、0.30wt%以下とする。However, if it exceeds 0.30 wt%, weldability and low-temperature toughness deteriorate. Therefore, its content is 0.01wt
% or more and 0.30wt% or less.
Si:脱酸剤として有効であるが、0.5 wt%を超
えると靭性をそこなう。したがって、その含有量は0,
5wt%以下とする。Si: Effective as a deoxidizing agent, but if it exceeds 0.5 wt%, toughness will be impaired. Therefore, its content is 0,
The content shall be 5 wt% or less.
Mn二強度、靭性を向上させるために有効な成分で、0
.5wt%以上を必要とする。しかし、2.0%1t%
を超えると溶接性が劣化する。したがって、その含有量
はQ、5wt%以上、2.0wt%とする。Mn2 is an effective component for improving strength and toughness, with 0
.. 5 wt% or more is required. However, 2.0%1t%
If it exceeds this, weldability will deteriorate. Therefore, the content of Q is 5 wt% or more and 2.0 wt%.
Ti:微量添加で大幅に強度を上昇させ、かつ、固溶N
による歪時効による靭性の劣化を防止する好ましい成分
である。その効果は、0.005 wt%以上で期待で
きるが、0.100wt%を超えると飽和する。したが
って、その含有量は0 、005w t%以上、0.1
00御t%以下とする。Ti: Significantly increases strength by adding a small amount, and also has solid solution N
This is a preferable component that prevents deterioration of toughness due to strain aging. The effect can be expected at 0.005 wt% or more, but it becomes saturated when it exceeds 0.100 wt%. Therefore, its content is 0.05 wt% or more, 0.1
00t% or less.
Nb : Tiと同様、微量添加で大幅に強度を上昇さ
せ、制御圧延との相乗効果により靭性を向上させる好ま
しい成分である。その効果は0.005 wt%以上で
期待できるが、0.10mt%を超えると飽和する。Nb: Like Ti, it is a preferred component that significantly increases strength when added in a small amount and improves toughness through a synergistic effect with controlled rolling. The effect can be expected at 0.005 wt% or more, but it becomes saturated when it exceeds 0.10 mt%.
したがって、その含有量は0 、005en t%以上
、0..010wt%以下とする。Therefore, its content is 0.005 ent% or more, 0.005 ent% or more. .. 010wt% or less.
SolAl : 鋼の脱酸に用いられる。その効果は0
.010wt%以上で生じ、0.100wt%を超える
と飽和する。したがって、その含有量は0.010wt
%以上、0.100wt%以下とする。SolAl: Used for deoxidizing steel. Its effect is 0
.. It occurs at 0.010 wt% or more, and becomes saturated when it exceeds 0.100 wt%. Therefore, its content is 0.010wt
% or more and 0.100wt% or less.
P:低温靭性を劣化させ、溶接時に高温割れを発生させ
ることがあることから、その含有量は0.025 im
t%以下とする。P: Because it can deteriorate low-temperature toughness and cause hot cracking during welding, its content is 0.025 im.
t% or less.
S:Mnと結合してA系介在物を生じて、靭性、延性を
劣化させることからその含有量は0.010wt%以下
とする。S: Since it combines with Mn to form A-based inclusions and deteriorates toughness and ductility, its content is set to 0.010 wt% or less.
N:靭性を劣化させるため可能な限り少ない方がよいが
、経済性を考慮し、その含有量は0.010wt%以下
とする。N: Since it deteriorates toughness, it is better to have as little as possible, but considering economic efficiency, the content is set to 0.010 wt% or less.
さらに、この発明においては、上記の成分組成例に加え
て、例えば、Cr、 Ni、 Mo、 V、 B、
Cu。Furthermore, in this invention, in addition to the above-mentioned component composition examples, for example, Cr, Ni, Mo, V, B,
Cu.
Ca、 REMのうちから選んだ1種又は2種以上を含
有させる。One or more selected from Ca and REM are contained.
これらの成分を含有させる主たる目的は、強度及び靭性
を向上させることにあり、それぞれの添加量は溶接性や
靭性を阻害しない範囲とする。The main purpose of containing these components is to improve strength and toughness, and the amount of each added is within a range that does not impede weldability or toughness.
すなわち、これらについては、以下の通りである。That is, these are as follows.
Cr、 Ni :これらの成分は、強度、靭性の向上に
有効な成分であるが、共に0.5wt%を超えて含有す
ると溶接性が劣化する。したがって、上限を共に0.5
wt%とする。Cr, Ni: These components are effective for improving strength and toughness, but if both are contained in excess of 0.5 wt%, weldability deteriorates. Therefore, both upper limits are 0.5
Let it be wt%.
Mo二強度、靭性の向上に有効な成分であるが、0.3
wt%を超えて含有すると溶接性が劣化する。Mo2 is an effective component for improving strength and toughness, but 0.3
If the content exceeds wt%, weldability will deteriorate.
したがって、上限を0.3wt%とする。Therefore, the upper limit is set to 0.3 wt%.
■:微量添加で大幅な強度の向上が期待できる成分であ
るが、0.15wt%を超えて含有するとその効果は飽
和し、溶接性が劣化する。したがって、上限を0.15
wt%とする。(2): This is a component that can be expected to significantly improve strength when added in a small amount, but if it is contained in an amount exceeding 0.15 wt%, the effect is saturated and weldability deteriorates. Therefore, we set the upper limit to 0.15
Let it be wt%.
B:焼入れ性を向上し、強度、靭性の向上をもたらす成
分であるが、0.0050wt%を超えて含有するとそ
の効果は飽和し、溶接性が劣化する。したがって、上限
を0.005wt%とする。B: A component that improves hardenability and improves strength and toughness, but if it is contained in an amount exceeding 0.0050 wt%, the effect is saturated and weldability deteriorates. Therefore, the upper limit is set to 0.005 wt%.
Cu:強度、靭性の向上に有効な成分であるが、0.5
0wt%を超えて含有すると溶接性が劣化する。Cu: An effective component for improving strength and toughness, but 0.5
If the content exceeds 0 wt%, weldability will deteriorate.
したがって、上限を0.5wt%とする。Therefore, the upper limit is set to 0.5 wt%.
Ca、REM:介在物の形態制御により、低温靭性、延
性に好ましいばかりでなく、セパレーション対策として
も好ましい成分である。しかし、共に、0.010 w
t%を超えて含有すると、溶接性、及び靭性の劣化をま
ねく。したがって、上限を共に0.010−t%とする
。Ca, REM: This component is not only preferable for low-temperature toughness and ductility by controlling the morphology of inclusions, but is also preferable as a countermeasure against separation. However, both 0.010 w
If the content exceeds t%, weldability and toughness will deteriorate. Therefore, both upper limits are set at 0.010-t%.
つぎに、この発明の熱間圧延条件、及びその後の冷却、
巻取り条件などについて以下に述べる。Next, the hot rolling conditions of this invention and subsequent cooling,
The winding conditions etc. will be described below.
熱間圧延:この発明は、粗圧延後のシートバーをコイル
状に巻き取ることが要点である。Hot rolling: The key point of this invention is to wind up the sheet bar after rough rolling into a coil shape.
すなわち、粗圧延を終えたシートバーをコイル状に巻き
取り、その後巻き戻しながら仕上げ圧延を行うことによ
り、粗圧延における被圧延材の先後端が、仕上げ圧延で
は逆転されて圧延されることになる。In other words, by winding the rough-rolled sheet bar into a coil shape and then performing finish rolling while unwinding, the leading and trailing ends of the material to be rolled during rough rolling are reversed during finish rolling. .
このため、粗圧延先後端での局部的な温度低下部は兎も
角とて、圧延先行端側から後尾端側にかけて不可避に生
じる温度勾配の下で、被圧延材が仕上げ圧延では温度の
低い粗圧延での後尾端側から圧延されることになり、仕
上げ圧延では被圧延材全長の温度が均一化される。For this reason, the local temperature drop at the trailing edge of the rough rolling tip is inevitable, and under the temperature gradient that inevitably occurs from the rolling leading edge to the trailing edge, the material to be rolled has a low temperature during finish rolling. The material is rolled from the trailing end side during rough rolling, and the temperature of the entire length of the material to be rolled is made uniform during finish rolling.
しかも粗圧延後コイル状に巻取ることによる、温度の均
一化効果があり、特に粗圧延での圧延先端の局部的温度
低下部分は、粗圧延後コイル内に巻き込まれることによ
り復熱し、均一化した温度となり、仕上げ圧延されるこ
とになる。Moreover, by winding it into a coil after rough rolling, there is an effect of uniformizing the temperature. In particular, the localized temperature drop at the rolling tip during rough rolling is reheated by being rolled into the coil after rough rolling, and the temperature is made uniform. At this temperature, finish rolling is performed.
さらに、粗圧延後のシートバーをコイル状に巻取ること
により、先行するシートバーとの接続を容易にし、この
接続により最初及び最終の圧延材を除いて仕上げ圧延で
は圧延端のない圧延ができ、したがって、仕上げ圧延で
の圧延端の局部的温度低下がなくなる。Furthermore, by winding the sheet bar after rough rolling into a coil, it is easy to connect it to the preceding sheet bar, and this connection allows rolling without rolling edges in finish rolling, except for the first and last rolled material. , Therefore, there is no local temperature drop at the rolling end during finish rolling.
かくすることにより、従来散見された被圧延材の先後端
側の圧延温度外れや、圧延温度合わせを行うための圧延
速度の増速に伴う圧延歪の不均一化を排除し、製品コイ
ル全長にわたり均等な材質が得られる。By doing this, it is possible to eliminate the deviation of the rolling temperature at the leading and trailing ends of the rolled material and the unevenness of rolling strain caused by increasing the rolling speed to adjust the rolling temperature, which has been observed in the past. A uniform material can be obtained.
つぎに圧延条件において、950℃以下の圧下率を′!
50%以上とする理由は、この温度より高い場合、及び
この加工率より低い場合、共にオーステナイト中への変
形帯の導入が不十分となり、最終的に得られる組織が微
細化せず、十分な強度靭性が得られなくなるためであり
、
さらに、圧延終了温度範囲を700℃以上800℃以下
とするのは、この温度範囲より高いとオーステナイト中
に導入された変形帯から生成する単位面積当りのフェラ
イト粒の数が減少するので最終的に得られる組織が微細
化せず、また、この温度範囲より低いと、多量のフェラ
イトが生成した以後も圧延加工することになるので、フ
ェライトの温間加工に基づく異方性が大きくなること、
及び靭性が劣化することによるものである。Next, under the rolling conditions, set the rolling reduction rate to 950°C or less!
The reason why it is set to 50% or more is that if the temperature is higher than this and if the processing rate is lower than this, the introduction of deformation bands into the austenite will be insufficient, the final structure will not be refined, and it will not be sufficiently refined. This is because strength and toughness cannot be obtained.Furthermore, the reason why the rolling end temperature range is set to 700°C or more and 800°C or less is that if the temperature is higher than this range, ferrite per unit area will be generated from the deformed band introduced into the austenite. Since the number of grains decreases, the final structure will not become finer, and if the temperature is lower than this range, a large amount of ferrite will be generated and rolling will continue, so it is difficult to warmly process ferrite. The anisotropy based on
This is due to deterioration of toughness.
冷却速度:冷却速度が遅いとPの粒界偏析に基づ(脆性
が生じやすくなると同時に、フェライト粒の粒成長が起
り、強度、靭性が確保できなくなる。このため、冷却速
度は5℃/S以上を必要とする。Cooling rate: If the cooling rate is slow, due to grain boundary segregation of P (brittleness is likely to occur), grain growth of ferrite grains occurs, making it impossible to ensure strength and toughness.For this reason, the cooling rate is 5℃/S. or more is required.
巻取り温度:高い巻取り温度では、Nb、 Ti等の析
出物による強化を有効に生かせず、Pの粒界偏析に基づ
く脆化が生じ易くなるので600℃以下とする必要があ
り、逆に巻取り温度が低いとコイル形状の不良を招き易
く、歩出りを悪くすると共に、鋼中に固溶C,Nが残存
しやすくなり、歪み時効性によくないので450℃以上
を必要とする。Winding temperature: If the winding temperature is high, the strengthening by precipitates such as Nb and Ti cannot be effectively utilized, and embrittlement due to grain boundary segregation of P tends to occur, so it must be kept at 600°C or less. If the winding temperature is low, it tends to lead to defects in the coil shape, resulting in poor yield, and solid solution C and N tend to remain in the steel, which is not good for strain aging properties, so a temperature of 450°C or higher is required. .
つぎに、圧延条件の内、靭性に大きく影響する圧延終了
温度についての実験結果を以下に記す。Next, among the rolling conditions, experimental results regarding the rolling end temperature, which greatly affects toughness, will be described below.
スニ」暖
C: 0.07wt %、 Si : 0.14w
t %、 Mn 二 1.42wt %、Nb :
0.04wt%、SolAl : 0.02wt%、P
: 0.008wt%、S : 0.002wt%、
N : 0.003 wt%の成分組成を有する鋼片素
材を、圧延終了温度を変化させる下記の熱延条件で、板
厚5閣に圧延し、得られた熱延板の靭性を調査した。Warm C: 0.07wt%, Si: 0.14w
t%, Mn2 1.42wt%, Nb:
0.04wt%, SolAl: 0.02wt%, P
: 0.008wt%, S: 0.002wt%,
A steel billet material having a component composition of N: 0.003 wt% was rolled to a thickness of 5 mm under the following hot rolling conditions in which the rolling end temperature was varied, and the toughness of the obtained hot rolled sheet was investigated.
圧延開始温度: 1150℃
粗圧延後シートバーの巻取り温度: 1000℃950
℃以下での圧下率エフ0%
圧延終了温度−670℃〜830℃
冷却速度:30℃/S
製品巻取り温度二500℃
これらの調査結果をまとめて第2図に示す。Rolling start temperature: 1150℃ Winding temperature of sheet bar after rough rolling: 1000℃950
Rolling reduction ratio F0% at temperatures below 0.degree. C. Rolling end temperature -670.degree. C. to 830.degree. C. Cooling rate: 30.degree. C./S Product winding temperature 2500.degree. C. The results of these investigations are summarized in FIG. 2.
第2図から明らかなように、圧延終了温度がこの発明の
限定範囲700℃から800”Cの間では、vTsが一
100″C以下と優れた靭性を示しているが、この発明
の限定範囲を外れる温度ではvTsが一100℃以上と
靭性に劣っている。したがって高靭性を得るためには、
圧延終了温度は700℃から800℃の温度範囲にする
必要がある。As is clear from FIG. 2, when the rolling end temperature is within the limited range of 700°C to 800"C of the present invention, excellent toughness is exhibited with vTs of 1100"C or less; At temperatures outside of this range, vTs is 1100°C or higher, resulting in poor toughness. Therefore, in order to obtain high toughness,
The rolling end temperature must be in the range of 700°C to 800°C.
(実施例)
l五■上
転炉で溶製した、
C: 0.08wt%、Si : 0.14wt%、M
n : 1.4wt%、Ti : 0.03wt%、N
b : 0.04wt%、SolAl : 0.02w
t%、Pro。008wt%、S : 0.002wt
%、N : 0.004wt%、の成分組成を有するこ
の発明の適合鋼を用い、熱間圧延を行って、熱延板コイ
ルとした。(Example) Smelted in a 15-cm upper converter furnace, C: 0.08wt%, Si: 0.14wt%, M
n: 1.4wt%, Ti: 0.03wt%, N
b: 0.04wt%, SolAl: 0.02w
t%, Pro. 008wt%, S: 0.002wt
%, N: 0.004 wt%, and hot rolling was performed using the compatible steel of the present invention to obtain a hot-rolled sheet coil.
熱間圧延条件は、
圧延開始温度: 1150℃、
粗圧延後シートバーの巻取り温度: 1000℃195
0℃以下の圧下率ニア0%、
圧延終了温度ニア50”C1
冷却速度;30℃/S、
製品巻取り温度;500℃1
仕上げ板厚=5閣、
で行ない、かつ、仕上げ圧延では、粗圧延後巻き取った
シートバーのコイル先後端を先行材及び後続材にそれぞ
れ接続して、圧延を連続的に行う方法で熱延板コイルを
製造し、この発明の適合例とした。Hot rolling conditions are as follows: Rolling start temperature: 1150°C, Coiling temperature of sheet bar after rough rolling: 1000°C 195
Rolling ratio near 0% below 0°C, rolling end temperature near 50”C1, cooling rate: 30°C/S, product winding temperature: 500°C1, finishing plate thickness = 5 mm, and in the finish rolling, rough A hot-rolled sheet coil was manufactured by a method in which the leading and trailing ends of the coil of a sheet bar wound up after rolling were connected to the preceding material and the succeeding material, respectively, and rolling was performed continuously, and this was used as an example adapted to the present invention.
一方、通常圧延材として、上記熱間圧延条件において、
粗圧延後のシートバーのコイル巻取りを行わず、また地
圧延材との接続も行わず、単独で圧延した熱延板コイル
を比較例とした。On the other hand, as a normally rolled material, under the above hot rolling conditions,
A comparative example was a hot-rolled sheet coil that was rolled independently without winding the sheet bar after rough rolling or connecting it to the ground-rolled material.
これら、熱延板コイルの長手方向の、靭性、引張特性を
調査した。この調査結果、すなわち、コ′イル長手方向
の靭性、引張特性の変化を第1図に示す。The toughness and tensile properties of these hot-rolled sheet coils in the longitudinal direction were investigated. The results of this investigation, ie, changes in toughness and tensile properties in the longitudinal direction of the coil, are shown in Figure 1.
第1図から明らかなように、比較例は、コイル両端にお
いて、靭性引張特性の劣化が大きく、かつ、圧延先端側
から後端側にかけてYSが漸増する傾向を示しており、
コイル全長にわたる均一性に劣っている。As is clear from FIG. 1, in the comparative example, the toughness and tensile properties deteriorated significantly at both ends of the coil, and YS showed a tendency to gradually increase from the rolling tip side to the rolling end side.
Poor uniformity over the entire length of the coil.
これに対し、適合例はコイル端部に多少の変化はあるも
のの全長にわたり均一な特性が得られており、均一性に
優れていることを示している。On the other hand, in the adapted example, although there were some changes at the ends of the coil, uniform characteristics were obtained over the entire length, indicating excellent uniformity.
z旌1
通常の方法で溶製した、表1に示す成分組成を有するこ
の発明の適合鋼21鋼種、比較鋼3鋼種、計24鋼種を
、表2に示す熱間圧延条件で圧延を行ない、板厚5mの
熱延板とした。z旌1 21 compatible steel types of the present invention and 3 comparative steel types, a total of 24 steel types, having the chemical composition shown in Table 1 and melted by a conventional method, were rolled under the hot rolling conditions shown in Table 2, A hot-rolled plate with a thickness of 5 m was used.
なお、表1にはP、S、Nが、この発明の限定範囲を外
れる鋼記号り、E、Fを比較鋼として示し、また、表2
には、これらの鋼を用いて製造した熱延板(試料Nα1
0〜12)を、熱間圧延条件がこの発明の限定範囲を外
れる熱延板(試料No、 4〜9)と共に比較例として
示した。In addition, in Table 1, P, S, and N are steel symbols that are outside the limited range of this invention, and E and F are shown as comparative steels, and Table 2
Hot-rolled sheets manufactured using these steels (sample Nα1
0 to 12) were shown as comparative examples together with hot rolled sheets (sample Nos. 4 to 9) whose hot rolling conditions were outside the limited range of the present invention.
これらの熱延板について、引張特性、靭性を調査した。The tensile properties and toughness of these hot rolled sheets were investigated.
上記調査結果は、熱間圧延条件とともに表2に示してい
るが、表2から明らかなように、比較例、すなわち、
圧延条件がこの発明の限定範囲を外れた、試料隘4 (
950℃以下の圧下率が少ない)試料No、5 (圧延
終了温度が低い)
試料階6(圧延終了温度が高い)
試料阻7(巻取り温度が高い)
試料Nα8(巻取り温度が低い)
試料Fk1.9 (圧延終了後の冷却速度が遅い)の各
試料では高靭性が得られず、
また、鋼の化学成分組成において、P、S、Nが、それ
ぞれこの発明の好適範囲の上限を外れた、試料10.1
1.12の各試料でも高靭性が得られない。The above investigation results are shown in Table 2 together with the hot rolling conditions.
(low rolling reduction of 950°C or less) Sample No. 5 (low rolling end temperature) Sample No. 6 (high rolling end temperature) Sample No. 7 (high winding temperature) Sample No. 8 (low winding temperature) Sample High toughness could not be obtained in the samples with Fk1.9 (slow cooling rate after rolling), and in the chemical composition of the steel, P, S, and N were each outside the upper limit of the preferred range of this invention. Sample 10.1
High toughness cannot be obtained in each sample of No. 1.12.
上記比較例に対し、この発明の適合例は、全て高靭性、
高強度が得られている。In contrast to the above comparative examples, all the applicable examples of the present invention have high toughness,
High strength is obtained.
(発明の効果)
この発明は、高靭性・高張力熱延鋼板向けの成分組成に
なる鋼片素材を、熱間圧延する際、粗圧延後の被圧延材
をコイル状に巻き取り、粗圧延での先後端と仕上げ圧延
での先後端を遊点させ、かつ、複数コイルを接続し、連
続して仕上げ圧延を行うことにより、コイル全長にわた
る均−性優れる高靭性・高張力熱延鋼板を製造するもの
で、この発明により、高靭性・高張力熱延銅板が安定し
て得られるばかりでなく、歩走りの向上が計れる。(Effects of the Invention) This invention provides the following advantages: When hot rolling a steel billet material having a chemical composition for high toughness/high tensile strength hot rolled steel sheet, the material to be rolled after rough rolling is wound into a coil shape, By making the leading and trailing ends of the coils loose and the leading and trailing ends of the finish rolling, and by connecting multiple coils and performing continuous finish rolling, we can produce high-toughness, high-strength hot-rolled steel sheets with excellent uniformity over the entire length of the coils. According to the present invention, not only a high-toughness, high-tensile-strength hot-rolled copper plate can be stably obtained, but also the walking performance can be improved.
第1図は、この発明の適合例と比較例について、コイル
長手方向の靭性、引張特性の変化を示すグラフ、及び、
第2図は、圧延終了温度と靭性との関係を示すグラフで
ある。FIG. 1 is a graph showing changes in toughness and tensile properties in the longitudinal direction of the coil for examples adapted to the present invention and comparative examples, and FIG. 2 is a graph showing the relationship between rolling end temperature and toughness.
Claims (1)
0.5wt%以下 Mn:0.5wt%以上、2.0wt%以下SolAl
:0.01wt%以上、0.10wt%以下P:0.0
25wt%以下 S:0.010wt%以下、及び、 N:0.0050wt%以下、 を含み、かつ Ti・・・0.005wt%以上、0.100wt%以
下、及びNb・・・0.005wt%以上、0.100
wt%以下、のうちから選んだ1種又は2種を含有し、
残部は鉄及び不可避不純物の組成になる連続鋳造鋼片素
材を熱間圧延する際、 粗圧延段階を経たシートバーを一旦コイル 状に巻き取り、その後、巻き終り端から仕上げ圧延を、
950℃以下での圧下率が50%以上で、圧延終了温度
が700℃以上、800℃以下の範囲にて開始し、その
後端に、後続するシートバーコイルの巻き終り端を接続
して、仕上げ圧延を連続的に行ない、この仕上げ圧延に
続いて、5℃/S以上の冷却速度で急冷し、450℃以
上、600℃以下の温度範囲で巻取ることを特徴とする
均一性に優れる高靭性・高張力熱延鋼板の製造方法。 2、C:0.01wt%以上、0.3wt%以下Si:
0.5wt%以下 Mn:0.5wt%以上、2.0wt%以下SolAl
:0.01wt%以上、0.10wt%以下P:0.0
25wt%以下 S:0.010wt%以下、及び、 N:0.0050wt%以下、 と、 Ti・・・0.005wt%以上、0.100wt%以
下、及びNb・・・0.005wt%以上、0.100
wt%以下、のうちから選んだ1種又は2種を含み、か
つCr:0.5wt%以下、 Ni:0.5wt%以下、 Mo:0.3wt%以下、 V:0.15wt%以下、 B:0.0050wt%以下、 Cu:0.50wt%以下、 Ca:0.010wt%以下、及び REM:0.010wt%以下、 のうちから選んだ1種又は2種以上を含有し、残部は鉄
及び不可避不純物の組成になる連続鋳造鋼片素材を熱間
圧延する際、 粗圧延段階を経たシートバーを一旦コイル 状に巻き取り、その後、巻き終り端から仕上げ圧延を、
950℃以下での圧下率が50%以上で、圧延終了温度
が700℃以上、800℃以下の範囲にて開始し、その
後端に、後続するシートバーコイルの巻き終り端を接続
して、仕上げ圧延を連続的に行ない、この仕上げ圧延に
続いて、5℃/S以上の冷却速度で急冷し、450℃以
上、600℃以下の温度範囲で巻取ることを特徴とする
均一性に優れる高靭性・高張力熱延鋼板の製造方法。[Claims] 1. C: 0.01 wt% or more, 0.3 wt% or less Si:
0.5 wt% or less Mn: 0.5 wt% or more, 2.0 wt% or less SolAl
: 0.01wt% or more, 0.10wt% or less P: 0.0
25 wt% or less S: 0.010 wt% or less, and N: 0.0050 wt% or less, and Ti...0.005 wt% or more and 0.100 wt% or less, and Nb...0.005 wt% Above, 0.100
Contains one or two selected from wt% or less,
When hot rolling continuously cast billet material, the remainder of which consists of iron and unavoidable impurities, the sheet bar that has gone through the rough rolling stage is wound into a coil, and then finish rolling is performed from the end of the winding.
Start when the rolling reduction rate is 50% or more at 950°C or less and the rolling end temperature is in the range of 700°C or more and 800°C or less, and finish by connecting the winding end of the subsequent sheet bar coil to the rear end. High toughness with excellent uniformity characterized by continuous rolling, followed by finish rolling, rapid cooling at a cooling rate of 5°C/S or more, and coiling at a temperature range of 450°C or higher and 600°C or lower.・Manufacturing method for high-tensile hot-rolled steel sheets. 2.C: 0.01wt% or more, 0.3wt% or lessSi:
0.5 wt% or less Mn: 0.5 wt% or more, 2.0 wt% or less SolAl
: 0.01wt% or more, 0.10wt% or less P: 0.0
25 wt% or less S: 0.010 wt% or less, and N: 0.0050 wt% or less, Ti...0.005 wt% or more, 0.100 wt% or less, and Nb...0.005 wt% or more, 0.100
wt% or less, and Cr: 0.5wt% or less, Ni: 0.5wt% or less, Mo: 0.3wt% or less, V: 0.15wt% or less, Contains one or more selected from B: 0.0050 wt% or less, Cu: 0.50 wt% or less, Ca: 0.010 wt% or less, and REM: 0.010 wt% or less, and the remainder is When hot rolling continuously cast billet material with a composition of iron and unavoidable impurities, the sheet bar that has gone through the rough rolling stage is wound into a coil shape, and then finish rolling is performed from the end of the winding.
Start when the rolling reduction rate is 50% or more at 950°C or less and the rolling end temperature is in the range of 700°C or more and 800°C or less, and finish by connecting the winding end of the subsequent sheet bar coil to the rear end. High toughness with excellent uniformity characterized by continuous rolling, followed by finish rolling, rapid cooling at a cooling rate of 5°C/S or more, and coiling at a temperature range of 450°C or higher and 600°C or lower.・Manufacturing method for high-tensile hot-rolled steel sheets.
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JP2292167A JP2975087B2 (en) | 1990-10-31 | 1990-10-31 | Manufacturing method of high toughness and high tensile strength hot rolled steel sheet with excellent uniformity |
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Cited By (4)
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WO2003006699A1 (en) * | 2001-07-13 | 2003-01-23 | Nkk Corporation | High strength steel pipe having strength higher than that of api x65 grade |
JP2013035014A (en) * | 2011-08-08 | 2013-02-21 | Nippon Steel & Sumitomo Metal Corp | Method of producing thick steel sheet |
CN105420606A (en) * | 2015-12-14 | 2016-03-23 | 武汉钢铁(集团)公司 | High-strength and high-toughness hot rolled magnetic yoke steel with yield strength to be 550MPa grade and production method |
CN116334486A (en) * | 2023-03-22 | 2023-06-27 | 包头钢铁(集团)有限责任公司 | High-strength hot-rolled steel strip with excellent low-temperature impact toughness for automobile and manufacturing method thereof |
-
1990
- 1990-10-31 JP JP2292167A patent/JP2975087B2/en not_active Expired - Fee Related
Cited By (5)
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WO2003006699A1 (en) * | 2001-07-13 | 2003-01-23 | Nkk Corporation | High strength steel pipe having strength higher than that of api x65 grade |
US7959745B2 (en) * | 2001-07-13 | 2011-06-14 | Jfe Steel Corporation | High-strength steel pipe of API X65 grade or higher |
JP2013035014A (en) * | 2011-08-08 | 2013-02-21 | Nippon Steel & Sumitomo Metal Corp | Method of producing thick steel sheet |
CN105420606A (en) * | 2015-12-14 | 2016-03-23 | 武汉钢铁(集团)公司 | High-strength and high-toughness hot rolled magnetic yoke steel with yield strength to be 550MPa grade and production method |
CN116334486A (en) * | 2023-03-22 | 2023-06-27 | 包头钢铁(集团)有限责任公司 | High-strength hot-rolled steel strip with excellent low-temperature impact toughness for automobile and manufacturing method thereof |
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