JPH04235218A - Production of steel plate having high strength and high toughness - Google Patents
Production of steel plate having high strength and high toughnessInfo
- Publication number
- JPH04235218A JPH04235218A JP215891A JP215891A JPH04235218A JP H04235218 A JPH04235218 A JP H04235218A JP 215891 A JP215891 A JP 215891A JP 215891 A JP215891 A JP 215891A JP H04235218 A JPH04235218 A JP H04235218A
- Authority
- JP
- Japan
- Prior art keywords
- cooling
- strength
- rolling
- temperature
- transformation point
- 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.)
- Withdrawn
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 38
- 239000010959 steel Substances 0.000 title claims abstract description 38
- 238000004519 manufacturing process Methods 0.000 title claims description 21
- 238000001816 cooling Methods 0.000 claims abstract description 39
- 238000005096 rolling process Methods 0.000 claims abstract description 30
- 230000009466 transformation Effects 0.000 claims abstract description 28
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 238000003303 reheating Methods 0.000 claims abstract description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 14
- 229910052757 nitrogen Inorganic materials 0.000 claims description 12
- 229910052720 vanadium Inorganic materials 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052742 iron Inorganic materials 0.000 claims description 6
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 239000000126 substance Substances 0.000 abstract description 8
- 230000000694 effects Effects 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 9
- 239000002244 precipitate Substances 0.000 description 8
- 238000005728 strengthening Methods 0.000 description 7
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- 238000001556 precipitation Methods 0.000 description 5
- 239000006104 solid solution Substances 0.000 description 5
- 230000001965 increasing effect Effects 0.000 description 4
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052750 molybdenum Inorganic materials 0.000 description 3
- 238000010791 quenching Methods 0.000 description 3
- 230000000171 quenching effect Effects 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000009863 impact test Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、高強度高靱性鋼板の製
造方法に関し、さらに詳しくは、溶接性を向上するため
に Ｃ量を低減し、高価な元素であるＣｕとＮｉを多量
に添加することなく、安価に降伏強度４２ｋｇｆ／ｍｍ
２ 以上、引張強さ５４ｋｇｆ／ｍｍ２ 以上、ｖＴｒ
ｓ −８０℃以下の高強度高靱性鋼板の製造方法に関す
るものである。[Industrial Application Field] The present invention relates to a method for manufacturing high-strength, high-toughness steel sheets, and more specifically, in order to improve weldability, the amount of C is reduced and large amounts of Cu and Ni, which are expensive elements, are added. Yield strength of 42 kgf/mm at low cost without
2 or more, tensile strength 54kgf/mm2 or more, vTr
The present invention relates to a method for manufacturing a high-strength, high-toughness steel plate at -80°C or lower.
【０００２】0002
【従来の技術】従来から高強度で高靱性が得られる鋼板
の製造方法は数多く提案されており、これらの製造方法
の一つとして、Ｖ の添加とＮ 含有量を高くしものが
知られており、ＡＳＴＭ規格Ａ６３３ グレードＥお
よびＡ６７８ グレードＤにその例をみることができ
る。[Prior Art] A number of methods have been proposed for manufacturing steel sheets that can obtain high strength and high toughness, and one of these manufacturing methods is known to add V and increase the N content. Examples of this can be found in ASTM standards A633 Grade E and A678 Grade D.
【０００３】0003
【発明が解決しようとする課題】しかし、ＡＳＴＭ規格
Ａ６３３ グレードＥは焼きならし鋼板で、ＡＳＴＭ
規格Ａ６７８ グレードＤは焼入れ焼きもどし鋼板で
、いずれもオフラインの熱処理を対象にしたものであり
、エネルギコストが嵩むとともに、高強度、高靱性化に
限界がある。[Problem to be solved by the invention] However, ASTM standard A633 grade E is a normalized steel plate,
Standard A678 grade D is a quenched and tempered steel plate, and both are intended for off-line heat treatment, which increases energy costs and limits the ability to achieve high strength and high toughness.
【０００４】本発明は、制御圧延、制御冷却を駆使し、
単純にＶ の添加とＮ の含有量を高めるだけでなく、
他の化学成分の含有量も最適化することによって、低コ
ストの高強度高靱性鋼板の製造方法を提供することを目
的とする。[0004] The present invention makes full use of controlled rolling and controlled cooling,
In addition to simply adding V and increasing the N content,
It is an object of the present invention to provide a method for producing a low-cost, high-strength, high-toughness steel plate by optimizing the content of other chemical components.
【０００５】[0005]
【課題を解決するための手段】本発明者らは、Ｖ−高Ｎ
の成分系を基本に、高強度高靱性鋼板を低コストで製
造する方法について、種々研究を重ねた結果、Ｖ−高Ｎ
の成分系に他の化学成分を調整し、加熱温度、圧延条
件、冷却条件等を適切に制御することによって、低コス
トで高強度高靱性鋼板の製造が可能であるという知見を
得て本発明に至ったものである。[Means for Solving the Problems] The present inventors have discovered that V-high N
As a result of various research into methods for producing high-strength, high-toughness steel sheets at low cost based on the composition system of
The present invention was based on the knowledge that it is possible to manufacture high-strength, high-toughness steel sheets at low cost by adjusting other chemical components to the chemical composition and appropriately controlling heating temperature, rolling conditions, cooling conditions, etc. This is what led to this.
【０００６】第１発明は、Ｃ：０．０１〜０．１０％、
Ｓｉ：０．０５〜０．５０％、 Ｍｎ：０．８０〜２
．５ ％、Ｓ：０．００５ ％以下、Ａｌ：０．００５
〜０．０４０ ％、Ｎｂ：０．００５〜０．１０％、
Ｖ：０．０３０〜０．１５０ ％、Ｔｉ：０．００５％
以下、Ｎ：０．００８０〜０．０２００％を含有し、残
部Ｆｅおよび不可避不純物からなる鋼片を ９５０〜１
１５０℃の温度範囲に加熱後、 ９００℃〜Ａｒ３ 変
態点の温度範囲で全圧下率４０％以上の圧延を行い、Ａ
ｒ３ 変態点以上の温度で圧延を終了したのち、 ２℃
／ｓｅｃ以上の冷却速度で ６００〜４００ ℃の温度
まで冷却し、それ以後空冷する高強度高靱性鋼板の製造
方法である。[0006] The first invention includes C: 0.01 to 0.10%,
Si: 0.05-0.50%, Mn: 0.80-2
．． 5%, S: 0.005% or less, Al: 0.005
~0.040%, Nb:0.005~0.10%,
V: 0.030-0.150%, Ti: 0.005%
Hereinafter, a steel piece containing N: 0.0080 to 0.0200% and the balance consisting of Fe and unavoidable impurities is 950 to 1
After heating to a temperature range of 150°C, rolling is performed at a total reduction rate of 40% or more in a temperature range of 900°C to Ar3 transformation point, and A
r3 After finishing rolling at a temperature above the transformation point, 2℃
This is a method for producing a high-strength, high-toughness steel plate, in which the steel plate is cooled to a temperature of 600 to 400° C. at a cooling rate of /sec or more, and then air-cooled.
【０００７】第２発明は、Ｃ：０．０１〜０．１０％、
Ｓｉ：０．０５〜０．５０％、 Ｍｎ：０．８０〜２
．５ ％、Ｓ：０．００５ ％以下、Ａｌ：０．００５
〜０．０４０ ％、Ｎｂ：０．００５〜０．１０％、
Ｖ：０．０３０〜０．１５０ ％、Ｔｉ：０．００５％
以下、Ｎ：０．００８０〜０．０２００％を含有し、残
部Ｆｅおよび不可避不純物からなる鋼片を ９５０〜１
１５０℃の温度範囲に加熱後、 ９００℃〜Ａｒ３ 変
態点の温度範囲で全圧下率４０％以上の圧延を行い、Ａ
ｒ３ 変態点以上の温度で圧延を終了したのち、 ２℃
／ｓｅｃ以上の冷却速度で ６００〜４００ ℃の温度
まで冷却したのち、 ５５０℃〜Ａｃ１ 変態点温度に
再加熱する高強度高靱性鋼板の製造方法である。[0007] The second invention is C: 0.01 to 0.10%,
Si: 0.05-0.50%, Mn: 0.80-2
．． 5%, S: 0.005% or less, Al: 0.005
~0.040%, Nb:0.005~0.10%,
V: 0.030-0.150%, Ti: 0.005%
Hereinafter, a steel piece containing N: 0.0080 to 0.0200% and the balance consisting of Fe and unavoidable impurities is 950 to 1
After heating to a temperature range of 150°C, rolling is performed at a total reduction rate of 40% or more in a temperature range of 900°C to Ar3 transformation point, and A
r3 After finishing rolling at a temperature above the transformation point, 2℃
This is a method for producing a high-strength, high-toughness steel plate, in which the steel plate is cooled to a temperature of 600 to 400°C at a cooling rate of /sec or more, and then reheated to a transformation point temperature of 550°C to Ac1.
【０００８】第３発明は、Ｃ：０．０１〜０．１０％、
Ｓｉ：０．０５〜０．５０％、 Ｍｎ：０．８０〜２
．５ ％、Ｓ：０．００５ ％以下、Ａｌ：０．００５
〜０．０４０ ％、Ｎｂ：０．００５〜０．１０％、
Ｖ：０．０３０〜０．１５０ ％、Ｔｉ：０．００５％
以下、Ｎ：０．００８０〜０．０２００％を含有し、残
部Ｆｅおよび不可避不純物からなる鋼片を ９５０〜１
１５０℃の温度範囲に加熱後、 ９００℃〜Ａｒ３ 変
態点の温度範囲で全圧下率４０％以上の圧延を行い、Ａ
ｒ３ 変態点以上の温度で圧延を終了したのち、 ２℃
／ｓｅｃ以上の冷却速度で ４００℃以下の温度まで冷
却したのち、 ５５０℃〜Ａｃ１変態点温度に再加熱す
る高強度高靱性鋼板の製造方法である。[0008] The third invention is C: 0.01 to 0.10%,
Si: 0.05-0.50%, Mn: 0.80-2
．． 5%, S: 0.005% or less, Al: 0.005
~0.040%, Nb:0.005~0.10%,
V: 0.030-0.150%, Ti: 0.005%
Hereinafter, a steel piece containing N: 0.0080 to 0.0200% and the balance consisting of Fe and unavoidable impurities is 950 to 1
After heating to a temperature range of 150°C, rolling is performed at a total reduction rate of 40% or more in a temperature range of 900°C to Ar3 transformation point, and A
r3 After finishing rolling at a temperature above the transformation point, 2℃
This is a method for producing a high-strength, high-toughness steel plate, in which the steel plate is cooled to a temperature of 400°C or less at a cooling rate of 1/sec or more, and then reheated to 550°C to an Ac1 transformation point temperature.
【０００９】第４発明は、Ｃｕ：０．１〜１．０ ％、
Ｎｉ：０．１〜１．０ ％、 Ｃｒ：０．０１〜０．５
０％、 Ｍｏ：０．０１〜０．５０％、 Ｃａ：０．０
００５〜０．００５０％、ＲＥＭ：０．００５〜０．０
５０ ％の内から選んだ一種または二種以上を含有する
請求項１、２または３記載の高強度高靱性鋼板の製造方
法である。[0009] The fourth invention is Cu: 0.1 to 1.0%,
Ni: 0.1-1.0%, Cr: 0.01-0.5
0%, Mo: 0.01-0.50%, Ca: 0.0
005-0.0050%, REM: 0.005-0.0
4. The method for producing a high-strength, high-toughness steel plate according to claim 1, 2 or 3, wherein the steel plate contains one or more selected from 50%.
【００１０】0010
【作用】以下に、本発明における化学成分の限定理由に
ついて説明する。Ｃ は、溶接性を害するため低い方が
望ましく、また、圧延前の鋼片加熱時に低温の加熱温度
においてもＮｂの固溶量を多くするためにも低い方が望
ましく、このため、上限を０．１０％とした。しかし、
強度確保のためには、０．０１％以上の添加が必要であ
る。したがって、 Ｃ添加量は０．０１〜０．１０％の
範囲とする。[Operation] The reasons for limiting the chemical components in the present invention will be explained below. It is desirable that C be low because it impairs weldability, and it is also desirable that it be low in order to increase the amount of solid solution of Nb even at low heating temperatures during heating of the steel billet before rolling. Therefore, the upper limit is set to 0. .10%. but,
In order to ensure strength, it is necessary to add 0.01% or more. Therefore, the amount of C added is in the range of 0.01 to 0.10%.
【００１１】Ｓｉは、製鋼時の鋼の脱酸と鋼の強化に必
要な元素であり、そのためには、０．０５％以上の添加
が必要である。しかし、０．５０％を超えて過多に添加
すると溶接性および靱性を劣化させる。したがって、Ｓ
ｉ添加量は０．０５〜０．５０％の範囲とする。[0011]Si is an element necessary for deoxidizing and strengthening steel during steel manufacturing, and for this purpose, it is necessary to add 0.05% or more. However, if added in excess of more than 0.50%, weldability and toughness will deteriorate. Therefore, S
The amount of i added is in the range of 0.05 to 0.50%.
【００１２】Ｍｎは、強度確保のために少なくとも０．
８０％の添加が必要であるが、 ２．５％を超えて過多
に添加すると溶接性が劣化する。したがって、Ｍｎ添加
量は０．８０〜２．５ ％の範囲とする。[0012] Mn is at least 0.0% to ensure strength.
It is necessary to add 80%, but if it is added in excess of 2.5%, weldability will deteriorate. Therefore, the amount of Mn added is in the range of 0.80 to 2.5%.
【００１３】Ｓ は、ＭｎＳ 介在物の生成により、シ
ャルピ吸収エネルギを低下させる元素であるため、でき
るだけ低い方が望ましい。したがって、Ｓ 量は ０．
００５％以下とする。[0013] Since S is an element that lowers the Charpy absorption energy by forming MnS inclusions, it is desirable that it be as low as possible. Therefore, the amount of S is 0.
0.005% or less.
【００１４】Ａｌは、脱酸元素であり、 ０．００５％
以上の添加が望ましいが、一方、Ｎ とＡｌは親和力が
強いため、Ａｌの添加量が多いと、ＡｌとＮ が優先的
に結合して、本発明の特徴であるＶ またはＮｂとＮ
との結合による析出強化作用が低減するため、Ａｌ添加
量はできるだけ少ない方がよい。したがって、Ａｌ添加
量は ０．００５〜０．０４０ ％の範囲とする。[0014] Al is a deoxidizing element and contains 0.005%
On the other hand, since N and Al have a strong affinity, if the amount of Al added is large, Al and N will preferentially combine, resulting in V or Nb and N, which is a feature of the present invention.
The amount of Al added should be as small as possible because the precipitation strengthening effect due to the combination with the aluminum is reduced. Therefore, the amount of Al added is in the range of 0.005 to 0.040%.
【００１５】Ｎｂは、本発明の特徴とする元素の一つで
あり、圧延時の結晶粒細粒化による靱性向上効果および
圧延冷却後の析出強化効果を示す元素である。特に、Ｎ
ｂを添加せず Ｖの添加のみでは圧延時の未再結晶域の
拡大作用が小さいため、未再結晶域での圧下が十分とれ
ず結果として、フェライト粒が細粒化せず高靱性を確保
することができない。つまり、高靱性を得るためには、
Ｎｂの添加が必須である。しかし、０．１０％を超える
添加は靱性を損なう。したがって、Ｎｂ添加量は ０．
００５〜０．１００ ％の範囲とする。[0015] Nb is one of the elements characteristic of the present invention, and is an element that exhibits the effect of improving toughness through grain refinement during rolling and the effect of precipitation strengthening after rolling cooling. In particular, N
If only V is added without adding b, the effect of expanding the unrecrystallized area during rolling is small, so the reduction in the unrecrystallized area is not sufficient, and as a result, the ferrite grains do not become fine and high toughness is ensured. Can not do it. In other words, in order to obtain high toughness,
Addition of Nb is essential. However, addition of more than 0.10% impairs toughness. Therefore, the amount of Nb added is 0.
The range is 0.005% to 0.100%.
【００１６】Ｖは、本発明の特徴とする元素であり、特
に Ｎと結合させＶＮの微細析出物を多量にフェライト
中に分散させることにより、大幅な強度上昇が可能とな
る。
この効果を得るためには、 ０．０３０％以上添加する
必要がある。しかし、０．１５０ ％を超えて過多に添
加すると靱性を劣化させる。したがって、Ｖ 添加量は
０．０３０〜０．１５０ ％の範囲とする。V is an element that characterizes the present invention, and in particular, by combining it with N and dispersing a large amount of VN fine precipitates in ferrite, it is possible to significantly increase the strength. In order to obtain this effect, it is necessary to add 0.030% or more. However, if it is added in excess of 0.150%, the toughness will deteriorate. Therefore, the amount of V added is in the range of 0.030 to 0.150%.
【００１７】Ｎは、本発明の最も特徴とする元素であり
、 ＶまたはＮｂと結合して微細析出物となり大幅な強
度上昇効果を示す。特に、Ｖ と結合したときには、極
めて大きな強度上昇となる。この強度上昇効果を得るた
めには、０．００８０％以上の添加が必要であるが、０
．０２００％を超えて添加すると靱性を劣化させる。し
たがって、Ｎ 添加量は ０．００８〜０．０２００％
の範囲とする。[0017]N is the most characteristic element of the present invention, and combines with V or Nb to form fine precipitates and exhibits a significant strength-increasing effect. In particular, when combined with V 2 , there is an extremely large increase in strength. In order to obtain this strength increasing effect, it is necessary to add 0.0080% or more, but 0.0080% or more is required.
．． Addition of more than 0.0200% deteriorates toughness. Therefore, the amount of N added is 0.008 to 0.0200%
The range shall be .
【００１８】Ｔｉは、溶接熱影響部の靱性向上作用のた
めにしばしば用いられる元素であるが、Ｎ との親和力
が強く、Ｎ と優先的に結合するため、本発明の主眼と
するＶＮまたはＮｂ（ＣＮ）等の析出強化作用を効果的
に活用するには、逆に害となる。したがって、Ｔｉ添加
量は ０．００５％以下とする。Ti is an element often used to improve the toughness of the weld heat-affected zone, but since it has a strong affinity with N and preferentially bonds with N, Ti On the contrary, it is detrimental to effectively utilizing the precipitation strengthening effect of (CN) and the like. Therefore, the amount of Ti added should be 0.005% or less.
【００１９】Ｃｕ、Ｎｉは、靱性向上に有効な元素であ
り、この効果を得るためには ０．１％以上の添加が必
要である。しかし、これらの元素は高価であるため、で
きるだけ少量の添加が望ましく、上限を １．０％とす
る。したがって、ＣｕおよびＮｉ添加量はそれぞれ ０
．１〜１．０ ％の範囲とする。[0019] Cu and Ni are effective elements for improving toughness, and in order to obtain this effect, it is necessary to add 0.1% or more. However, since these elements are expensive, it is desirable to add as little as possible, and the upper limit is set at 1.0%. Therefore, the amounts of Cu and Ni added are each 0
．． The range is 1% to 1.0%.
【００２０】Ｃｒ、Ｍｏは、強度上昇に有効な元素であ
り、この効果を得るためには０．０１％以上の添加が必
要であるが、０．５０％を超えて多量に添加すると溶接
性をそこなう。したがって、ＣｒおよびＭｏ添加量はそ
れぞれ０．０１〜０．５０％の範囲とする。Cr and Mo are effective elements for increasing strength, and in order to obtain this effect, it is necessary to add 0.01% or more, but if they are added in large amounts exceeding 0.50%, weldability will deteriorate. damage Therefore, the amounts of Cr and Mo added are each in the range of 0.01 to 0.50%.
【００２１】Ｃａ、ＲＥＭ は、介在物の形態制御によ
る異方性の改善に有効な元素であり、その効果を発揮さ
せるためには、０．０００５％以上の添加が必要である
が、０．００５０％を超えて過多に添加すると靱性を劣
化させる。したがって、ＣａおよびＲＥＭ 添加量はそ
れぞれ０．０００５〜０．００５０％の範囲とする。[0021] Ca and REM are elements effective in improving anisotropy by controlling the morphology of inclusions, and in order to exhibit this effect, it is necessary to add 0.0005% or more, but 0.0005% or more is required. If added in excess of more than 0.050%, toughness will deteriorate. Therefore, the amounts of Ca and REM added are each in the range of 0.0005 to 0.0050%.
【００２２】つぎに、本発明の製造条件の限定理由につ
いて説明する。Next, the reasons for limiting the manufacturing conditions of the present invention will be explained.
【００２３】鋼片の加熱温度は、オーステナイト結晶粒
の粗大化を防止するため、低温の方が望ましい。しかし
、Ｎｂ、Ｖ の析出強化効果作用を得るためにはこれら
の一部または全てを固溶させる必要があるため、ある程
度の加熱温度を確保しなければならない。したがって、
本発明では、鋼片の加熱温度は、 ９５０〜１１５０℃
の範囲に限定する。[0023] The heating temperature of the steel piece is desirably low in order to prevent coarsening of austenite crystal grains. However, in order to obtain the precipitation-strengthening effect of Nb and V, it is necessary to dissolve some or all of them in solid solution, so a certain heating temperature must be ensured. therefore,
In the present invention, the heating temperature of the steel piece is 950 to 1150°C
limited to the range of
【００２４】フェライト結晶粒の微細化を図るためには
、変態前のオーステナイト結晶粒の微細化とフェライト
変態の核となる歪みの導入が必要であり、このためには
、 ９００℃以下 Ａｒ３変態点以上の温度域で全圧下
率４０％以上の圧延を行う必要がある。また、 Ａｒ３
変態点未満の温度域で圧延を行うと、変態したフェライ
トが加工され靱性が大きく劣化する。したがって、圧延
終了温度は Ａｒ３変態点以上に限定する。ここで、
Ａｒ３変態点は次式で定められる。Ａｒ３（℃）＝９１
０−３１０Ｃ−８０Ｍｎ−２０Ｃｕ−１５Ｃｒ−５５Ｎ
ｉ−８０Ｍｏ＋０．３５（ｔ−８）ただし、各元素は含
有量（％）で表す。ｔ は板厚で（ｍｍ）で表す。[0024] In order to refine the ferrite grains, it is necessary to refine the austenite grains before transformation and introduce strain that becomes the core of ferrite transformation. It is necessary to perform rolling at a total reduction rate of 40% or more in the above temperature range. Also, Ar3
If rolling is performed in a temperature range below the transformation point, the transformed ferrite will be processed and the toughness will be significantly degraded. Therefore, the rolling end temperature is limited to the Ar3 transformation point or higher. here,
The Ar3 transformation point is determined by the following equation. Ar3(℃)=91
0-310C-80Mn-20Cu-15Cr-55N
i-80Mo+0.35 (t-8) However, each element is expressed in content (%). t is the plate thickness expressed in (mm).
【００２５】本発明の製造方法のもう一つの特徴は、
Ａｒ３変態点以上の温度で圧延終了後、２℃／ｓｅｃ以
上の冷却速度で冷却（加速冷却または直接焼入れ）する
ことである。空冷する場合に比較して、 ２℃／ｓｅｃ
以上の冷却速度で水冷した場合の効果は、まず、組織的
にはフェライト結晶粒が微細化することであり、これに
より靱性が向上する。また、析出強化作用を有効に活用
できることから、大幅な強度上昇が可能となる。すなわ
ち、特に、Ｎｂ、Ｖ は、Ｎｂ（Ｃ，Ｎ）、 Ｖ（Ｃ，
Ｎ）（炭窒化物）あるいはこれらの複合析出物を生成し
、冷却速度の増大により、これら析出物の粒子サイズが
微細化するとともに粒子間隔が近くなり、強度が上昇す
る。したがって、圧延後の冷却速度は ２℃／ｓｅｃ以
上に限定する。Another feature of the manufacturing method of the present invention is that
After rolling is completed at a temperature equal to or higher than the Ar3 transformation point, cooling is performed at a cooling rate of 2° C./sec or higher (accelerated cooling or direct quenching). 2℃/sec compared to air cooling
The effect of water cooling at the above cooling rate is that the ferrite crystal grains become microstructurally finer, thereby improving toughness. Furthermore, since the precipitation strengthening effect can be effectively utilized, it is possible to significantly increase the strength. That is, in particular, Nb,V is Nb(C,N), V(C,
N) (carbonitride) or composite precipitates of these are formed, and as the cooling rate increases, the particle size of these precipitates becomes finer and the distance between the particles becomes closer, increasing the strength. Therefore, the cooling rate after rolling is limited to 2° C./sec or more.
【００２６】加速冷却の場合、冷却停止直後に微細なＮ
ｂ（Ｃ，Ｎ）や Ｖ（Ｃ，Ｎ）等が析出して強度を上昇
させる。この効果を有効に得るためには、Ｎｂ（Ｃ，Ｎ
）や Ｖ（Ｃ，Ｎ）等が析出しやすい ６００〜４００
℃の温度域まで冷却し、それ以後空冷する必要がある
。In the case of accelerated cooling, fine N
b(C,N), V(C,N), etc. precipitate and increase the strength. In order to effectively obtain this effect, Nb(C,N
) and V(C,N) are likely to precipitate 600-400
It is necessary to cool it down to a temperature range of ℃ and then air cooling.
【００２７】また、加速冷却後空冷した場合でも、上記
のように析出物による強度上昇はあるものの、全てが析
出しきれているわけではなく、まだ固溶したＮｂやＶ
が存在する。したがって、加速冷却後空冷したのち、さ
らに、再加熱することによって、未析出のＮｂやＶ を
炭窒化物として析出させ強度を上昇させることができる
。このためには、 ５５０℃〜Ａｃ１ 変態点温度に再
加熱する必要がある。ここで、 Ａｃ１変態点は次式で
定められる。
Ａｃ１（℃）＝７２３−１４Ｍｎ＋２２Ｓｉ−１４．４
Ｎｉ＋２３．３Ｃｒただし、各元素は含有量（％）で表
す。Furthermore, even when air cooling is performed after accelerated cooling, although there is an increase in strength due to the precipitates as described above, not all of the precipitates have completely precipitated, and Nb and V that are still in solid solution remain.
exists. Therefore, by performing accelerated cooling, air cooling, and then reheating, unprecipitated Nb and V 2 can be precipitated as carbonitrides to increase the strength. For this purpose, it is necessary to reheat to a transformation point temperature of 550° C. to Ac1. Here, the Ac1 transformation point is determined by the following equation. Ac1(℃)=723-14Mn+22Si-14.4
Ni+23.3Cr However, each element is expressed in content (%).
【００２８】また、 ４００℃以下の温度まで ２℃／
ｓｅｃ以上の冷却速度で冷却するいわゆる直接焼入れを
行うと、冷却後硬化組織が導入されるとともに、大部分
のＮｂ、Ｖ は炭窒化物として析出せず固溶したままと
なる。この固溶したままのＮｂ、Ｖ を再加熱して、炭
窒化物として析出させ強度の上昇を図る。このために、
４００℃以下の温度まで加速冷却したのち、 ５５０
℃〜Ａｃ１ 変態点温度に再加熱する必要がある。[0028] Furthermore, up to a temperature of 400°C or less, 2°C/
When so-called direct quenching is performed in which cooling is performed at a cooling rate of sec or more, a hardened structure is introduced after cooling, and most of Nb and V 2 do not precipitate as carbonitrides but remain in solid solution. The solid solution Nb and V are reheated to precipitate as carbonitrides to increase the strength. For this,
After accelerated cooling to a temperature of 400℃ or less, 550℃
°C to Ac1 It is necessary to reheat to the transformation point temperature.
【００２９】[0029]
【実施例】以下に実施例を挙げて本発明を説明するが、
本発明はこれら実施例により何ら限定されるものではな
い。[Examples] The present invention will be explained below with reference to Examples.
The present invention is not limited in any way by these Examples.
【００３０】供試鋼板は表１および表２に示す化学成分
を含有する鋼を常法により溶製、鋳造して得られた鋼片
を、表３に示す製造条件にしたがって、板厚２５〜５０
ｍｍに仕上げたものである。これらの鋼板から試験片を
採取し引張試験と衝撃試験を行った。その結果を表４に
示す。[0030] The test steel plates were obtained by melting and casting steel containing the chemical components shown in Tables 1 and 2 by a conventional method, and were made into plate thicknesses of 25 to 25 mm according to the manufacturing conditions shown in Table 3. 50
It is finished in mm. Test pieces were taken from these steel plates and subjected to tensile tests and impact tests. The results are shown in Table 4.
【００３１】[0031]
【表１】[Table 1]
【００３２】[0032]
【表２】[Table 2]
【００３３】[0033]
【表３】[Table 3]
【００３４】[0034]
【表４】[Table 4]
【００３５】表１および表２に化学成分を、表３に製造
条件を、表４に試験結果を示すが、本発明法による鋼板
Ｎｏ．１、５ 、６ 、７ 、１０、１１、１２、１３
はいずれもＹＳ（降伏強さ）４２ｋｇｆ／ｍｍ２ 以上
、ＴＳ（引張強さ）５４ｋｇｆ／ｍｍ２ 以上の高強度
を示すとともに、 −８０℃での衝撃吸収エネルギ （
ｖＥ−８０）が２０ｋｇｆ−ｍ 以上、ｖＴｒｓ（遷移
温度）が−８０ ℃以下と極めて良好な靱性を有してい
る。Tables 1 and 2 show the chemical composition, Table 3 shows the manufacturing conditions, and Table 4 shows the test results. 1, 5, 6, 7, 10, 11, 12, 13
Both exhibit high strength with YS (yield strength) of 42 kgf/mm2 or higher and TS (tensile strength) of 54 kgf/mm2 or higher, as well as shock absorption energy at -80℃ (
It has extremely good toughness, with vE-80) of 20 kgf-m or more and vTrs (transition temperature) of -80°C or less.
【００３６】これに対して、比較例Ｎｏ．２は、加熱温
度が高いため靱性が低下している。比較例Ｎｏ．３と８
は、圧延終了温度が低いため靱性が悪い。比較例Ｎｏ
．９は、 ９００℃以下の圧下率が小さいため靱性が悪
い。比較例Ｎｏ．４は、圧延終了後空冷しているため強
度が低く、靱性も低下している。比較例Ｎｏ．１４ は
、Ａｌ含有量が多いため強度が低い。比較例Ｎｏ．１５
は、Ｔｉ含有量が多いため強度が低く、靱性も悪い。
比較例Ｎｏ．１６ は、Ｎ 含有量が少ないため靱性が
悪い。比較例Ｎｏ．１７ は、Ｎｂ含有量が少ないため
靱性が悪い。比較例Ｎｏ．１８ は、Ｖ 含有量が少な
いため強度が低い。以上の実施例の結果からも明らかな
ように、本発明に係わる鋼板の製造方法は、高強度で低
温靱性の優れた鋼板の製造に適したものである。On the other hand, Comparative Example No. No. 2 has low toughness due to high heating temperature. Comparative example no. 3 and 8
has poor toughness because the rolling end temperature is low. Comparative example No.
．． No. 9 has poor toughness because the rolling reduction below 900°C is small. Comparative example no. No. 4 had low strength and low toughness because it was air cooled after rolling. Comparative example no. No. 14 has low strength due to high Al content. Comparative example no. 15
has low strength and poor toughness due to its high Ti content. Comparative example no. No. 16 has poor toughness due to low N content. Comparative example no. No. 17 has poor toughness due to low Nb content. Comparative example no. 18 has low strength due to low V content. As is clear from the results of the above examples, the method for producing a steel plate according to the present invention is suitable for producing a steel plate with high strength and excellent low-temperature toughness.
【００３７】[0037]
【発明の効果】以上説明したように、本発明は化学成分
の限定と加熱、圧延、冷却条件の限定による複合効果に
よるＮｂ、Ｖ の炭窒化物の析出強化とフェライト結晶
粒の微細化によって高強度、高靱性を有する鋼板を製造
するもので、本発明によればＹＳ４２ｋｇｆ／ｍｍ２
以上、ＴＳ５４ｋｇｆ／ｍｍ２ 以上の高強度と、ｖＴ
ｒｓ −８０℃以下の高靱性を有する高強度高靱性鋼板
を、焼入れ焼きもどしまたは焼きならし処理を施すこと
なく低コストで製造が可能である。Effects of the Invention As explained above, the present invention achieves high performance by precipitation strengthening of Nb and V carbonitrides and refinement of ferrite crystal grains due to the combined effect of limiting chemical components and limiting heating, rolling, and cooling conditions. It manufactures steel plates with high strength and high toughness, and according to the present invention, YS42kgf/mm2
Above, high strength of TS54kgf/mm2 or more and vT
A high-strength, high-toughness steel plate having high toughness of rs −80° C. or lower can be manufactured at low cost without performing quenching, tempering, or normalizing treatment.
Claims (4)
０．０５〜０．５０％、 Ｍｎ：０．８０〜２．５ ％
、Ｓ：０．００５ ％以下、Ａｌ：０．００５〜０．０
４０ ％、Ｎｂ：０．００５〜０．１０％、 Ｖ：０．
０３０〜０．１５０ ％、Ｔｉ：０．００５％以下、Ｎ
：０．００８０〜０．０２００％を含有し、残部Ｆｅお
よび不可避不純物からなる鋼片を ９５０〜１１５０℃
の温度範囲に加熱後、 ９００℃〜Ａｒ３ 変態点の温
度範囲で全圧下率４０％以上の圧延を行い、Ａｒ３ 変
態点以上の温度で圧延を終了したのち、２℃／ｓｅｃ以
上の冷却速度で ６００〜４００ ℃の温度まで冷却し
、それ以後空冷することを特徴とする高強度高靱性鋼板
の製造方法。[Claim 1] C: 0.01 to 0.10%, Si:
0.05-0.50%, Mn: 0.80-2.5%
, S: 0.005% or less, Al: 0.005-0.0
40%, Nb: 0.005-0.10%, V: 0.
030-0.150%, Ti: 0.005% or less, N
: 0.0080~0.0200%, with the balance consisting of Fe and unavoidable impurities at 950~1150℃
After heating to a temperature range of 900°C to Ar3 transformation point, rolling is performed at a total reduction rate of 40% or more, and after finishing the rolling at a temperature of Ar3 transformation point or higher, cooling is performed at a cooling rate of 2°C/sec or higher. A method for producing a high-strength, high-toughness steel plate, which comprises cooling to a temperature of 600 to 400°C, and then air cooling.
０．０５〜０．５０％、 Ｍｎ：０．８０〜２．５ ％
、Ｓ：０．００５ ％以下、Ａｌ：０．００５〜０．０
４０ ％、Ｎｂ：０．００５〜０．１０％、 Ｖ：０．
０３０〜０．１５０ ％、Ｔｉ：０．００５％以下、Ｎ
：０．００８０〜０．０２００％を含有し、残部Ｆｅお
よび不可避不純物からなる鋼片を ９５０〜１１５０℃
の温度範囲に加熱後、 ９００℃〜Ａｒ３ 変態点の温
度範囲で全圧下率４０％以上の圧延を行い、Ａｒ３ 変
態点以上の温度で圧延を終了したのち、２℃／ｓｅｃ以
上の冷却速度で ６００〜４００ ℃の温度まで冷却し
たのち、 ５５０℃〜Ａｃ１ 変態点温度に再加熱する
ことを特徴とす高強度高靱性鋼板の製造方法。[Claim 2] C: 0.01 to 0.10%, Si:
0.05-0.50%, Mn: 0.80-2.5%
, S: 0.005% or less, Al: 0.005-0.0
40%, Nb: 0.005-0.10%, V: 0.
030-0.150%, Ti: 0.005% or less, N
: 0.0080~0.0200%, with the balance consisting of Fe and unavoidable impurities at 950~1150℃
After heating to a temperature range of 900°C to Ar3 transformation point, rolling is performed at a total reduction rate of 40% or more, and after finishing the rolling at a temperature of Ar3 transformation point or higher, cooling is performed at a cooling rate of 2°C/sec or higher. A method for producing a high-strength, high-toughness steel plate, which comprises cooling to a temperature of 600 to 400°C and then reheating to a transformation point temperature of 550°C to Ac1.
０．０５〜０．５０％、 Ｍｎ：０．８０〜２．５ ％
、Ｓ：０．００５ ％以下、Ａｌ：０．００５〜０．０
４０ ％、Ｎｂ：０．００５〜０．１０％、 Ｖ：０．
０３０〜０．１５０ ％、Ｔｉ：０．００５％以下、Ｎ
：０．００８０〜０．０２００％を含有し、残部Ｆｅお
よび不可避不純物からなる鋼片を ９５０〜１１５０℃
の温度範囲に加熱後、 ９００℃〜Ａｒ３ 変態点の温
度範囲で全圧下率４０％以上の圧延を行い、Ａｒ３ 変
態点以上の温度で圧延を終了したのち、２℃／ｓｅｃ以
上の冷却速度で ４００℃以下の温度まで冷却したのち
、 ５５０℃〜Ａｃ１ 変態点温度に再加熱することを
特徴とす高強度高靱性鋼板の製造方法。[Claim 3] C: 0.01 to 0.10%, Si:
0.05-0.50%, Mn: 0.80-2.5%
, S: 0.005% or less, Al: 0.005-0.0
40%, Nb: 0.005-0.10%, V: 0.
030-0.150%, Ti: 0.005% or less, N
: 0.0080~0.0200%, with the balance consisting of Fe and unavoidable impurities at 950~1150℃
After heating to a temperature range of 900°C to Ar3 transformation point, rolling is performed at a total reduction rate of 40% or more, and after finishing the rolling at a temperature of Ar3 transformation point or higher, cooling is performed at a cooling rate of 2°C/sec or higher. A method for producing a high-strength, high-toughness steel plate, which comprises cooling to a temperature of 400°C or lower and then reheating to a transformation point temperature of 550°C to Ac1.
．１〜１．０ ％、 Ｃｒ：０．０１〜０．５０％、
Ｍｏ：０．０１〜０．５０％、 Ｃａ：０．０００５〜
０．００５０％、 ＲＥＭ：０．００５〜０．０５０
％の内から選んだ一種または二種以上を含有することを
特徴とする請求項１、２または３記載の高強度高靱性鋼
板の製造方法。[Claim 4] Cu: 0.1 to 1.0%, Ni: 0
．． 1 to 1.0%, Cr: 0.01 to 0.50%,
Mo: 0.01~0.50%, Ca: 0.0005~
0.0050%, REM: 0.005-0.050
The method for manufacturing a high-strength, high-toughness steel plate according to claim 1, 2 or 3, characterized in that the method contains one or more selected from the following.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP215891A JPH04235218A (en) | 1991-01-11 | 1991-01-11 | Production of steel plate having high strength and high toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP215891A JPH04235218A (en) | 1991-01-11 | 1991-01-11 | Production of steel plate having high strength and high toughness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04235218A true JPH04235218A (en) | 1992-08-24 |
Family
ID=11521551
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP215891A Withdrawn JPH04235218A (en) | 1991-01-11 | 1991-01-11 | Production of steel plate having high strength and high toughness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04235218A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007119884A (en) * | 2005-10-31 | 2007-05-17 | Jfe Steel Kk | Method for producing high strength and high toughness steel material excellent in strength at intermediate temperature zone |
| JP2007169747A (en) * | 2005-12-26 | 2007-07-05 | Jfe Steel Kk | Method for producing high-strength and high-toughness steel plate excellent in strength and deformability in middle temperature zone |
| CN103361551A (en) * | 2012-03-30 | 2013-10-23 | 鞍钢股份有限公司 | V-N microalloying-based high-strength and high-toughness ship plate and manufacturing method thereof |
-
1991
- 1991-01-11 JP JP215891A patent/JPH04235218A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007119884A (en) * | 2005-10-31 | 2007-05-17 | Jfe Steel Kk | Method for producing high strength and high toughness steel material excellent in strength at intermediate temperature zone |
| JP2007169747A (en) * | 2005-12-26 | 2007-07-05 | Jfe Steel Kk | Method for producing high-strength and high-toughness steel plate excellent in strength and deformability in middle temperature zone |
| CN103361551A (en) * | 2012-03-30 | 2013-10-23 | 鞍钢股份有限公司 | V-N microalloying-based high-strength and high-toughness ship plate and manufacturing method thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Application deemed to be withdrawn because no request for examination was validly filed |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19980514 |