JPH11335735A - Manufacture of extra thick shape steel excellent in weldability, strength and toughness - Google Patents
Manufacture of extra thick shape steel excellent in weldability, strength and toughnessInfo
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- JPH11335735A JPH11335735A JP5109399A JP5109399A JPH11335735A JP H11335735 A JPH11335735 A JP H11335735A JP 5109399 A JP5109399 A JP 5109399A JP 5109399 A JP5109399 A JP 5109399A JP H11335735 A JPH11335735 A JP H11335735A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、安価でありながら
溶接性、強度および靱性に優れた極厚形鋼の製造法に関
する。[0001] The present invention relates to a method for producing an extremely thick section steel which is inexpensive but excellent in weldability, strength and toughness.
【０００２】[0002]
【従来の技術】例えばフランジ厚さ、ウェブ厚さがとも
に50mmである極厚の圧延形鋼といった極厚の圧延鋼材で
は、一般的に圧延時の圧下率が小さくなりがちである。
そのため、圧延素材に充分な圧下を行い難くなることに
起因して、成品である圧延鋼材(以降の説明は極厚の圧
延形鋼を例にとる。) には強度低下が発生し易くなる。2. Description of the Related Art For example, an extremely thick rolled steel material such as an extremely thick rolled section steel having both a flange thickness and a web thickness of 50 mm tends to reduce the rolling reduction during rolling.
For this reason, it is difficult to sufficiently reduce the rolling material, so that a rolled steel material as a product (the following description takes an example of an extremely thick rolled steel) as an example is likely to cause a decrease in strength.
【０００３】このような強度低下を防止するには圧延形
鋼へ強度増加合金元素を添加すればよいが、強度増加合
金元素の添加量の増加に伴って、炭素当量Ceq.が増加
し、0.45％ (本明細書では、特にことわりがない限り
「％」は「重量％」を意味するものとする。) 以上にも
及ぶことが多い。このため、極厚の圧延形鋼では、フラ
ンジ厚さおよびウェブ厚さの増加に伴う溶接入熱量の増
大とあいまって、溶接性が著しく劣化してしまう。In order to prevent such a decrease in strength, it is sufficient to add a strength-increasing alloy element to the rolled section steel. However, as the addition amount of the strength-increasing alloy element increases, the carbon equivalent Ceq. % (In this specification, "%" means "% by weight" unless otherwise specified.) For this reason, in the case of an extremely thick rolled section steel, the weldability is remarkably deteriorated in combination with an increase in welding heat input accompanying an increase in flange thickness and web thickness.
【０００４】ところで、極厚の鋼板の高強度化を行う方
法として、従来より、焼入れ・焼戻しを行う方法、
圧延後に制御冷却を行う方法、低温圧延を行う方法が
知られている。しかし、これらの極厚の鋼板に対する高
強度化方法を、極厚の圧延形鋼に流用することはできな
い。[0004] By the way, as a method of increasing the strength of an extremely thick steel sheet, a method of performing quenching and tempering has conventionally been used.
A method of performing controlled cooling after rolling and a method of performing low-temperature rolling are known. However, these methods for increasing the strength of an extremely thick steel sheet cannot be applied to an extremely thick rolled section steel.
【０００５】すなわち、圧延形鋼は断面形状が複雑であ
るために、の焼入れ・焼戻しを行われたフランジとウ
ェブとには、焼入れ時の冷却、焼戻し時の加熱、さらに
はその後の冷却における加熱速度および冷却速度の差が
発生し、最終的に100 ℃以上にも及ぶ大きな温度差が発
生してしまう。そのため、ウェブ曲り等の変形が発生し
易くなり、生産性およびコストが著しく悪化してしま
う。That is, since the cross-sectional shape of a rolled section steel is complicated, the flange and the web which have been quenched and tempered have cooling during quenching, heating during tempering, and heating during subsequent cooling. Differences in speed and cooling rate occur, resulting in a large temperature difference of over 100 ° C. Therefore, deformation such as bending of the web is likely to occur, and productivity and cost are significantly deteriorated.
【０００６】また、の制御冷却を行うと、と同様
に、フランジおよびウェブそれぞれの冷却速度の差に起
因して100 ℃以上にも及ぶ大きな温度差が発生してしま
う。さらに、の低温・大圧下の圧延法は、一般的に鋼
板の圧延機に比較すると形鋼の圧延機のミル剛性が低い
ために、形鋼の圧延に用いることはできない。Further, when the controlled cooling is performed, a large temperature difference of 100 ° C. or more occurs due to the difference in the cooling rate between the flange and the web similarly to the above. In addition, the low-temperature and large-pressure rolling method cannot be used for rolling a section steel because the rolling rigidity of a section steel mill is generally lower than that of a steel sheet rolling mill.
【０００７】そのため、例えば特開平８−197104号公報
や同８−197105号公報には、圧延ラインにオンライン冷
却設備を設置し、950 ℃以上に高温仕上げした鋼材に強
制冷却を行うことにより、極厚Ｈ形鋼の強度を、溶接性
を損なうことなく、確保する発明が提案されている。[0007] For example, Japanese Unexamined Patent Publication Nos. Hei 8-197104 and Hei 8-197105 disclose an on-line cooling facility in a rolling line and forcibly cool steel material finished at a high temperature of 950 ° C or more. An invention has been proposed to ensure the strength of a thick H-section steel without impairing the weldability.
【０００８】また、特開平９−125138号公報には、1170
℃以下の粗形鋼片に複数パスの中間圧延と複数パスの仕
上圧延とを行うとともに、中間圧延と仕上圧延とのそれ
ぞれにおいては、短時間のフランジ水冷を行うことによ
り、溶接性に優れた高靱性および高張力の極厚Ｈ形鋼を
製造する発明が提案されている。Japanese Patent Application Laid-Open No. 9-125138 discloses 1170
Performs multiple passes of intermediate rolling and multiple passes of finish rolling on coarse shaped steel slabs at or below ℃, and in each of intermediate rolling and finish rolling, by performing short-time flange water cooling, excellent weldability An invention for producing a high-toughness and high-strength ultra-thick H-section steel has been proposed.
【０００９】[0009]
【発明が解決しようとする課題】しかし、特開平８−19
7104号公報または同８−197105号公報により提案された
発明では、圧延ラインに冷却設備を設置する必要があ
り、相当の設備費が必要になってしまう。また、圧延後
のＨ形鋼の全長は通常100 ｍ以上にも及ぶため、長手方
向の温度ばらつきを制御する必要もあるが、このような
温度制御は極めて難しいとともに、このためにさらに生
産性およびコストが増加してしまう。さらに、設置スペ
ースの問題で圧延ラインに冷却設備を設置できない場合
には実施できない。SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No.
In the invention proposed in Japanese Patent Application Laid-Open No. 7104 or 8-197105, it is necessary to install a cooling facility in the rolling line, which requires considerable facility costs. In addition, since the overall length of the H-section steel after rolling is generally 100 m or more, it is necessary to control the temperature variation in the longitudinal direction. However, such temperature control is extremely difficult, and therefore, productivity and productivity are further increased. The cost will increase. Furthermore, it cannot be implemented when cooling facilities cannot be installed on the rolling line due to installation space problems.
【００１０】また、特開平９−125138号公報により提案
された発明は、低温で中間圧延および仕上圧延を行うこ
とになり、一般的な形鋼の圧延機では実施できない。さ
らに、現在、板厚40mm以上の極厚鋼板に要求される機械
的性能は、JIS G 3136に示されるように、降伏点：295
〜415 N/mm2 、引張強さ：490 〜610 N/mm2、伸び：23
％以上、０℃Ｖノッチシャルピー吸収エネルギー：27Ｊ
以上とされている。しかし、阪神大震災の教訓から、柱
材用の形鋼に対しては、JIS G 3136に示される０℃Ｖノ
ッチシャルピー吸収エネルギー：27Ｊ以上では靱性が足
りず、少なくとも100 Ｊは必要であるとの報告がなされ
ている。また、板厚40mm以上の極厚鋼板の降伏点の規定
値は、薄鋼板よりも、下限値で20N/mm2 低く設定されて
いる。しかし、ユーザー側では極厚鋼板に関しても325
〜445 N/mm2 の降伏点を有することが要求されている。The invention proposed in Japanese Patent Application Laid-Open No. 9-125138 involves intermediate rolling and finish rolling at a low temperature, and cannot be carried out by a general section steel rolling mill. Further, at present, the mechanical performance required for an extremely thick steel plate having a thickness of 40 mm or more, as shown in JIS G 3136, yield point: 295
415415 N / mm 2 , tensile strength: 490 610 N / mm 2 , elongation: 23
%, 0 ° C V Notch Charpy absorbed energy: 27J
That is all. However, from the lessons learned from the Great Hanshin Earthquake, toughness for column steel is not sufficient at 0 ° C V notch Charpy absorbed energy: 27 J or more specified in JIS G 3136, and at least 100 J is required. Reports have been made. Further, the specified value of the yield point of an extremely thick steel plate having a thickness of 40 mm or more is set to be 20 N / mm 2 lower than the thin steel plate at the lower limit. However, on the user's side, 325
It is required to have a yield point of 445445 N / mm 2 .
【００１１】したがって、柱材用の形鋼に関しては、前
述した従来の提案によっては得られないような、高靱性
化および高強度化を図る必要がある。ここに、本発明の
目的は、設備増設を行うことなく、溶接性、強度および
靱性に優れた極厚形鋼を、熱処理を行うことなく、製造
する方法を提供することである。Therefore, it is necessary to increase the toughness and the strength of the section steel for the column material, which cannot be obtained by the above-mentioned conventional proposal. Here, an object of the present invention is to provide a method for producing an extremely thick section steel having excellent weldability, strength, and toughness without performing additional heat treatment, without performing heat treatment.
【００１２】具体的には、降伏点：325 〜445 N/mm2 、
引張強さ：490 〜610 N/mm2 、伸び：23％以上、０℃Ｖ
ノッチシャルピー吸収エネルギー：100 Ｊ以上である、
板厚が40mm以上の50キロ級極厚形鋼を、熱処理を行うこ
となく、製造する方法を提供することである。Specifically, the yield point: 325 to 445 N / mm 2 ,
Tensile strength: 490-610 N / mm 2 , elongation: 23% or more, 0 ° C V
Notch Charpy absorbed energy: 100 J or more,
It is an object of the present invention to provide a method for manufacturing a 50 kg-class ultra-thick steel plate having a thickness of 40 mm or more without performing heat treatment.
【００１３】[0013]
【課題を解決するための手段】本発明は、上記課題に鑑
みてなされたものであり、目的に応じたマイクロアロイ
の複合添加を行ったスラブを用い、このスラブを圧延素
材として適正温度域で適正圧下率の圧延を行うことによ
り、圧延後の熱処理や強制冷却を必要とせず、低炭素当
量であって溶接性、強度および靱性に優れた50キロ級極
厚形鋼を製造するものである。DISCLOSURE OF THE INVENTION The present invention has been made in view of the above problems, and uses a slab to which a microalloy is added in combination according to the purpose, and uses this slab as a rolled material in an appropriate temperature range. By performing rolling at an appropriate rolling reduction, it does not require heat treatment or forced cooling after rolling, and produces a 50 kg ultra-thick section steel with low carbon equivalent and excellent weldability, strength and toughness. .
【００１４】ここに、本発明の要旨とするところは、
Ｃ：0.05〜0.12％、Si：0.05〜0.55％、Mn：1.00〜1.90
％、Ｐ：0.020 ％以下、Ｓ：0.008 ％以下、Cu：1.00％
以下、Nb：0.020 〜0.050 ％、Ｖ：0.050 〜0.100 ％、
Ti：0.010 〜0.030 ％、sol.Al：0.005 〜0.030 ％、
Ｎ：0.003 〜0.005 ％、残部Feおよび不可避不純物から
なる鋼組成を有し、下記式により規定される炭素当量
Ceq.が0.34〜0.40％であるスラブを、Ar3 変態点以下の
温度域から1250〜1350℃へ加熱して熱間粗圧延を行い、
950 〜900 ℃の温度域で熱間中間圧延を開始し、Ar3 変
態点以上のオーステナイト未再結晶温度域までに総圧下
率が35％以上となるように熱間中間圧延を行い、さらに
熱間仕上げ圧延を行い、その後室温まで放冷することを
特徴とする溶接性、強度および靱性に優れた極厚形鋼の
製造法である。Here, the gist of the present invention is as follows.
C: 0.05 to 0.12%, Si: 0.05 to 0.55%, Mn: 1.00 to 1.90
%, P: 0.020% or less, S: 0.008% or less, Cu: 1.00%
Hereinafter, Nb: 0.020 to 0.050%, V: 0.050 to 0.100%,
Ti: 0.010-0.030%, sol.Al: 0.005-0.030%,
N: a steel composition consisting of 0.003 to 0.005%, the balance being Fe and unavoidable impurities, and a carbon equivalent defined by the following formula
A slab having a Ceq. Of 0.34 to 0.40% is heated from a temperature range below the Ar 3 transformation point to 1250 to 1350 ° C. to perform hot rough rolling,
Hot intermediate rolling is started in the temperature range of 950 to 900 ° C, and hot intermediate rolling is performed so that the total draft becomes 35% or more by the austenite non-recrystallization temperature range above the Ar 3 transformation point. This is a method for producing an ultra-thick section steel excellent in weldability, strength and toughness, which is characterized by performing finish rolling and then allowing to cool to room temperature.
【００１５】 Ceq(%)＝C(%)+Si/24(%)+Mn/6(%)+Ni/40(%)+Cr/5(%)+Mo/4(%)+V/14(%) ・・・・・ 別の観点からは、本発明は、Ｃ：0.05〜0.12％、Si：0.
05〜0.55％、Mn：1.00〜1.90％、Ｐ：0.020 ％以下、
Ｓ：0.008 ％以下、Cu：1.00％以下、Nb：0.020〜0.050
％、Ｖ：0.050 〜0.100 ％、Ti：0.005 〜0.030 ％、s
ol.Al：0.005 〜0.050 ％、Ｎ：0.001 〜0.005 ％、残
部Feおよび不可避不純物からなる鋼組成を有し、上記
式により規定される炭素当量Ceq.が0.32〜0.40％である
スラブを、Ar3 変態点以下の温度域から1250〜1350℃へ
加熱して熱間粗圧延を行い、950 〜900 ℃の温度域で熱
間中間圧延を開始し、Ar3 変態点以上のオーステナイト
未再結晶温度域までに総圧下率が35％以上となるように
熱間中間圧延を行い、さらに熱間仕上げ圧延を行い、そ
の後室温まで放冷することを特徴とする溶接性、強度お
よび靱性に優れた極厚形鋼の製造法である。Ceq (%) = C (%) + Si / 24 (%) + Mn / 6 (%) + Ni / 40 (%) + Cr / 5 (%) + Mo / 4 (%) + V / 14 (%) ·········· From another point of view, the present invention provides C: 0.05 to 0.12% and Si:
05 ~ 0.55%, Mn: 1.00 ~ 1.90%, P: 0.020% or less,
S: 0.008% or less, Cu: 1.00% or less, Nb: 0.020 to 0.050
%, V: 0.050 to 0.100%, Ti: 0.005 to 0.030%, s
ol. Al: 0.005 to 0.050%, N: 0.001 to 0.005%, a slab having a steel composition including the balance of Fe and unavoidable impurities, and having a carbon equivalent Ceq. 3 is heated from a temperature range below the transformation point to 1250 to 1350 ° C. performs rough hot rolling, 950 hot intermediate rolling is started at a temperature range of to 900 ° C., Ar 3 transformation point or more of the austenite non-recrystallization temperature Hot-rolling, so that the total rolling reduction is at least 35%, and then hot-finish rolling, followed by cooling to room temperature. This is a method for manufacturing thick section steel.
【００１６】上記の本発明にかかる溶接性、強度および
靱性に優れた極厚形鋼の製造法では、(1) スラブが連続
鋳造スラブである場合には、連続鋳造後にAr3 変態点以
下の温度域への冷却を行うこと、(2) (1) 項における冷
却は、徐冷、水冷または空冷であること、(3) 熱間粗圧
延を終了した後に、引き続き、または一旦冷却を行って
から、熱間中間圧延を行うこと、(4)Ar3変態点は、得ら
れる成品のフランジ厚さをｔ(mm)とした場合の下記式
により算出されるか、または実測により求められるこ
と、(5) オーステナイト未再結晶温度域は、850 〜750
℃であること、(6) スラブは、さらに、Ni：1.00％以
下、Cr：0.50％以下、Mo：0.50％以下、およびＢ：0.00
03〜0.0050％からなる群から選ばれた一種以上を含有す
ることが、いずれも望ましい。According to the method for producing an extremely thick section steel having excellent weldability, strength, and toughness according to the present invention, (1) when the slab is a continuous cast slab, after the continuous cast, the slab has an Ar 3 transformation point or less. (2) Cooling in paragraph (1) shall be slow cooling, water cooling or air cooling. (3) After completion of hot rough rolling, continue or once cool from performing the hot intermediate rolling, (4) Ar 3 transformation point, it sought or is calculated by the following formula in the case of the finished products of the flange thickness obtained was t (mm), or by actual measurement, (5) The austenite non-recrystallization temperature range is 850 to 750.
(6) The slab further contains Ni: 1.00% or less, Cr: 0.50% or less, Mo: 0.50% or less, and B: 0.00
It is desirable that the composition contains at least one selected from the group consisting of 03 to 0.0050%.
【００１７】 Ar3(℃) ＝910-310xC-80xMn-20xCu-15xCr-55xNi-80xMo+0.35x(t-8) ・・・・・ 上記の本発明にかかる溶接性、強度および靱性に優れた
極厚形鋼の製造法において、「形鋼」には、建築構造物
の柱材として用いられる形鋼が包含される。例えば、Ｈ
形鋼、Ｉ形鋼、溝形鋼、等辺山形鋼、不等辺山形鋼さら
にはＴ形鋼等を例示することができる。Ar 3 (° C.) = 910-310xC-80xMn-20xCu-15xCr-55xNi-80xMo + 0.35x (t-8) Excellent in weldability, strength and toughness according to the present invention described above. In the method for producing an extremely thick section steel, the section steel includes a section steel used as a pillar of a building structure. For example, H
Shaped steel, I-shaped steel, channel steel, equilateral angle steel, unequal angle angle steel, and T-shaped steel can be exemplified.
【００１８】[0018]
【発明の実施の形態】以下、本発明にかかる溶接性、強
度および靱性に優れた極厚形鋼の製造法を、詳細に説明
する。なお、本実施形態では、スラブが連続鋳造スラブ
であるとともに形鋼がＨ形鋼である場合を例にとって、
説明を行う。まず、用いるスラブの組成を限定する理由
を説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing an extremely thick section steel having excellent weldability, strength and toughness according to the present invention will be described in detail. In addition, in this embodiment, taking the case where the slab is a continuous cast slab and the section steel is an H-section steel as an example,
Give an explanation. First, the reason for limiting the composition of the slab to be used will be described.
【００１９】(Ｃ：0.05〜0.12％)Ｃは、0.05％以上含有
することにより鋼の強度および硬度を増加させるが、0.
12％を超えて過剰に含有すると、鋼の靱性を損なうとと
もに炭素当量Ceq.を大幅に増加して溶接性を著しく損な
う。そこで、本発明では、Ｃ含有量は0.05％以上0.12％
以下と限定する。Ｃ含有量の上限は0.10％、下限は0.08
％であることが望ましい。(C: 0.05 to 0.12%) C increases the strength and hardness of steel by containing 0.05% or more.
If it is contained in excess of 12%, the toughness of the steel is impaired, and the carbon equivalent Ceq. Is significantly increased, thereby significantly impairing the weldability. Therefore, in the present invention, the C content is 0.05% or more and 0.12%
Limited to the following. The upper limit of C content is 0.10% and the lower limit is 0.08
% Is desirable.
【００２０】(Si：0.05〜0.55％)Siは、強力な脱酸剤と
して有効であるとともに、鋼の強度を増加させる。Si含
有量が0.05％未満では充分な脱酸効果が期待できず、一
方0.55％を超えると鋼の靱性を損なう。そこで、本発明
では、Si含有量は0.05％以上0.55％以下と限定する。(Si: 0.05-0.55%) Si is effective as a strong deoxidizing agent and increases the strength of steel. If the Si content is less than 0.05%, a sufficient deoxidizing effect cannot be expected, while if it exceeds 0.55%, the toughness of the steel is impaired. Therefore, in the present invention, the Si content is limited to 0.05% or more and 0.55% or less.
【００２１】(Mn：1.00〜1.90％)Mnは、強度および靱性
を向上させる。Mn含有量が1.00％未満では強度および靱
性の向上効果が期待できず、一方1.90％を超えると強度
増加作用が飽和するとともに靱性が低下する。そこで、
本発明では、Mn含有量は1.00％以上1.90％以下と限定す
る。(Mn: 1.00 to 1.90%) Mn improves strength and toughness. If the Mn content is less than 1.00%, the effect of improving strength and toughness cannot be expected, while if it exceeds 1.90%, the effect of increasing strength is saturated and the toughness is reduced. Therefore,
In the present invention, the Mn content is limited to 1.00% to 1.90%.
【００２２】(Ｐ：0.020 ％以下)Ｐは、鋼中に不可避不
純物として含有され、鋼の靱性を低下させるため、少な
いほうが望ましい。特に、Ｐ含有量が0.020 ％を超える
と、連続鋳造スラブを用いた場合には、スラブ割れ等の
悪影響がある。そこで、本発明では、Ｐ含有量は0.020
％以下と限定する。(P: 0.020% or less) Since P is contained as an unavoidable impurity in the steel and lowers the toughness of the steel, it is desirable that P is small. In particular, when the P content exceeds 0.020%, when a continuously cast slab is used, there are adverse effects such as slab cracking. Therefore, in the present invention, the P content is 0.020
% Or less.
【００２３】(Ｓ：0.008 ％以下)Ｓは、鋼中に不可避不
純物として含有され、鋼の靱性を低下させるため、少な
いほうが望ましい。特に、Ｐ含有量が0.008 ％を超える
と、連続鋳造スラブを用いた場合には、スラブ割れ等の
悪影響がある。そこで、本発明では、Ｐ含有量は0.008
％以下と限定する。(S: 0.008% or less) Since S is contained as an unavoidable impurity in the steel and lowers the toughness of the steel, it is desirable that S is small. In particular, when the P content exceeds 0.008%, when a continuously cast slab is used, there is an adverse effect such as slab cracking. Therefore, in the present invention, the P content is 0.008.
% Or less.
【００２４】(Cu：1.00％以下)Cuは、鋼の強度および靱
性を向上させるが、含有量が1.00％を超えると、コスト
上昇が著しくなる。そこで、本発明では、Cu含有量は1.
00％以下と限定する。(Cu: 1.00% or less) Cu improves the strength and toughness of the steel. However, if the content exceeds 1.00%, the cost increases significantly. Therefore, in the present invention, the Cu content is 1.
Limited to 00% or less.
【００２５】(Nb：0.020 〜0.050 ％)Nbは、鋼中におい
て炭窒化物を形成して強度の増加をもたらすとともに、
オーステナイト結晶粒を微細化して鋼の靱性を向上させ
る。Nbによる靱性向上効果は、1200℃以下ではTiよりも
大きい。Nb含有量が0.020 ％未満では強度増加が期待で
きず、一方0.050 ％を超えると強度増加が飽和しコスト
が上昇するだけである。そこで、本発明では、Nb含有量
は0.020 ％以上0.050 ％以下と限定する。Nb含有量の上
限は0.040 ％、下限は0.030 ％であることが望ましい。(Nb: 0.020 to 0.050%) Nb forms carbonitrides in the steel to increase the strength,
Austenite grains are refined to improve the toughness of steel. The effect of improving toughness by Nb is greater than that of Ti at 1200 ° C or lower. If the Nb content is less than 0.020%, no increase in strength can be expected, while if it exceeds 0.050%, the increase in strength is saturated and only the cost increases. Therefore, in the present invention, the Nb content is limited to not less than 0.020% and not more than 0.050%. It is desirable that the upper limit of the Nb content is 0.040% and the lower limit is 0.030%.
【００２６】(Ｖ：0.050 〜0.100 ％)Ｖは、鋼中におい
て炭窒化物を形成して強度増加をもたらす。Ｖ含有量が
0.050 ％未満ではかかる効果が期待できず、一方0.100
％を超えるとスラブ品質に問題が発生する。そこで、本
発明では、Ｖ含有量は0.050 ％以上0.100 ％以下と限定
する。Ｖ含有量の上限は0.080 ％、下限は0.060 ％であ
ることが望ましい。(V: 0.050 to 0.100%) V forms carbonitrides in the steel to increase the strength. V content
If it is less than 0.050%, such effects cannot be expected, while 0.100%
%, Problems occur in slab quality. Therefore, in the present invention, the V content is limited to 0.050% or more and 0.100% or less. It is desirable that the upper limit of the V content be 0.080% and the lower limit be 0.060%.
【００２７】(Ti：0.005 〜0.030 ％)Tiは、鋼中におい
て炭窒化物を形成しオーステナイト結晶粒を微細化さ
せ、鋼の靱性を向上させる。靱性向上効果は、1200℃以
上の高温側ではNbよりも大きい。つまり、スラブ加熱に
よりオーステナイト結晶粒が加熱温度に応じて粗大化す
るが、Tiは炭窒化物を形成し1250〜1350℃の加熱温度に
おいても固溶せずオーステナイト結晶粒の粗大化を抑制
する。よって、圧延開始時の初期オーステナイト粒径を
最小限に確保することにより後のフェライト粒径を微細
化することができる。また、その微細化作用により溶接
部靱性も向上する。Ti含有量が0.005 ％未満では靱性向
上効果が期待できず、一方0.030 ％を超えると、靱性向
上効果は飽和しコストが上昇するだけとなる。そこで、
本発明では、Ti含有量は0.005 ％以上0.030 ％以下と限
定する。同様の観点から、Ti含有量の上限は0.025 ％で
あることが望ましい。一方、Ti含有量の下限は0.010 ％
であることが望ましく、0.015 ％であることがさらに望
ましい。(Ti: 0.005 to 0.030%) Ti forms carbonitrides in the steel, refines austenite crystal grains, and improves the toughness of the steel. The effect of improving toughness is larger than that of Nb on the high temperature side of 1200 ° C. or higher. In other words, austenite crystal grains are coarsened by slab heating in accordance with the heating temperature, but Ti forms carbonitrides and does not form a solid solution even at a heating temperature of 1250 to 1350 ° C., and suppresses coarsening of austenite crystal grains. Therefore, by keeping the initial austenite grain size at the start of rolling to a minimum, the subsequent ferrite grain size can be reduced. In addition, the toughness of the weld is also improved by the refining action. If the Ti content is less than 0.005%, the effect of improving toughness cannot be expected, while if it exceeds 0.030%, the effect of improving toughness saturates and the cost only increases. Therefore,
In the present invention, the Ti content is limited to 0.005% or more and 0.030% or less. From the same viewpoint, the upper limit of the Ti content is preferably 0.025%. On the other hand, the lower limit of the Ti content is 0.010%
And more preferably 0.015%.
【００２８】(sol.Al：0.005 〜0.050 ％)Alは、鋼の強
力な脱酸剤として使用され、sol.Alの含有量が0.005 ％
未満では脱酸作用が不足し、一方0.050 ％を超えるとコ
ストが上昇するだけとなる。そこで、本発明では、sol.
Al含有量は0.005 以上0.050 ％以下と限定する。同様の
観点から、sol.Al含有量の上限は0.030 ％であることが
望ましい。(Sol.Al: 0.005 to 0.050%) Al is used as a strong deoxidizing agent for steel, and the content of sol.Al is 0.005%.
If it is less than 0.05%, the deoxidizing effect will be insufficient, while if it exceeds 0.050%, the cost will only increase. Therefore, in the present invention, sol.
The Al content is limited to 0.005 to 0.050%. From the same viewpoint, the upper limit of the sol.Al content is desirably 0.030%.
【００２９】(Ｎ：0.001 〜0.005 ％)Ｎは、Nb、Ｖ、Ti
と窒化物を生成し、強度および靱性を向上させる。特
に、スラブ加熱時において分散しているTiＮがオーステ
ナイト結晶粒の粗大化を防止するため、Ｈ形鋼特有の高
温加熱に有効である。Ｎ含有量が0.001 ％未満ではかか
る効果が期待できず、一方0.005 ％を超えると鋼の溶接
性が損なわれる。そこで、本発明では、Ｎ含有量は0.00
1 ％以上0.005 ％以下と限定する。同様の観点から、Ｎ
含有量の下限は0.003 ％であることが望ましい。(N: 0.001 to 0.005%) N is Nb, V, Ti
And nitrides to improve strength and toughness. In particular, since TiN dispersed during slab heating prevents austenite crystal grains from becoming coarse, it is effective for high-temperature heating unique to H-section steel. If the N content is less than 0.001%, such effects cannot be expected, while if it exceeds 0.005%, the weldability of steel is impaired. Therefore, in the present invention, the N content is 0.00
Limited to 1% or more and 0.005% or less. From a similar perspective, N
It is desirable that the lower limit of the content is 0.003%.
【００３０】本発明で用いるスラブは、上記以外に、N
i、Cr、MoおよびＢからなる群から選ばれた１種以上
を、任意添加元素として含有してもよい。以下、これら
の任意添加元素についても説明する。The slab used in the present invention may be N
One or more selected from the group consisting of i, Cr, Mo and B may be contained as an optional additive element. Hereinafter, these optional elements will be described.
【００３１】(Ni：1.00％以下)Niは、鋼の強度と靱性と
をともに向上させるが、その含有量をいたずらに増加さ
せることはその効果以上にコスト上昇をもたらす。そこ
で、Niを添加する場合には、その含有量は1.00％以下と
限定することが望ましい。(Ni: 1.00% or less) Ni improves both the strength and toughness of the steel, but unnecessarily increasing its content results in a cost increase beyond its effect. Therefore, when adding Ni, its content is preferably limited to 1.00% or less.
【００３２】(Cr：0.50％以下)Crは、鋼の強度と靱性と
をともに向上させるが、その含有量をいたずらに増加さ
せることはその効果以上にコスト上昇をもたらす。そこ
で、Crを添加する場合には、その含有量は0.50％以下と
限定することが望ましい。(Cr: 0.50% or less) Cr improves both the strength and the toughness of the steel, but unnecessarily increasing its content causes a cost increase more than its effect. Therefore, when Cr is added, its content is desirably limited to 0.50% or less.
【００３３】(Mo：0.50％以下)Moは、鋼の強度と靱性と
をともに向上させるが、その含有量をいたずらに増加さ
せることはその効果以上にコスト上昇をもたらす。そこ
で、Moを添加する場合には、その含有量は0.50％以下と
限定することが望ましい。(Mo: 0.50% or less) Mo improves both the strength and toughness of the steel, but unnecessarily increasing its content results in a cost increase more than the effect. Therefore, when Mo is added, its content is preferably limited to 0.50% or less.
【００３４】(Ｂ：0.0003〜0.0050％)Ｂは、0.0003％以
上含有することにより鋼の強度を増加させるが、0.0050
％超含有するとその効果以上にコスト上昇をもたらす。
そこで、Ｂを添加する場合には、その含有量は0.0003％
以上0.0050％以下と限定することが望ましい。上記以外
の組成は、Feおよび不可避的不純物である。(B: 0.0003% to 0.0050%) B contains 0.0003% or more to increase the strength of steel.
%, The cost increases more than the effect.
Therefore, when B is added, its content is 0.0003%
It is desirable to limit it to at least 0.0050%. Compositions other than the above are Fe and unavoidable impurities.
【００３５】(炭素当量Ceq.：0.32〜0.40％)本発明で用
いるスラブは、式により規定される炭素当量Ceq.が0.
32〜0.40％である。炭素当量Ceq.は溶接性を判断する指
標の一種であり、炭素当量Ceq.が上昇するにつれて溶接
性が悪化する。炭素当量Ceq.が0.40％を越えると溶接割
れ等の弊害が発生し、一方0.32％を下回ると鋼の強度を
所望の程度に保つことができない。そこで、本発明で
は、炭素当量Ceq.を0.32％以上0.40％％以下と限定す
る。同様の観点から、炭素当量Ceq.の下限は0.34％であ
ることが望ましい。(Carbon equivalent Ceq .: 0.32-0.40%) The slab used in the present invention has a carbon equivalent Ceq.
It is 32 to 0.40%. The carbon equivalent Ceq. Is a kind of index for determining weldability, and the weldability deteriorates as the carbon equivalent Ceq. Increases. If the carbon equivalent Ceq. Exceeds 0.40%, harmful effects such as welding cracks will occur, while if it is less than 0.32%, the strength of the steel cannot be maintained at a desired level. Therefore, in the present invention, the carbon equivalent Ceq. Is limited to 0.32% to 0.40 %%. From the same viewpoint, the lower limit of the carbon equivalent Ceq. Is desirably 0.34%.
【００３６】(Ar3 変態点以下の温度域へのスラブ冷却)
本実施形態と同様に、Ｈ形鋼用スラブは連続鋳造により
製造される。連続鋳造直後のスラブは、結晶粒が最も粗
大化している。この状態から圧延を開始すると、最終的
にフェライト結晶粒も大きくなって、その分だけ強度お
よび靱性の低下を招く。したがって、連続鋳造後に一旦
Ar3 変態点以下の温度域へのスラブ冷却を行い、その後
に再加熱することにより、フェライトをオーステナイト
に変態させ圧延初期オーステナイト結晶粒の微細化を行
うことが効果的である。そのため、連続鋳造スラブを、
オーステナイトがフェライトへ変態するAr3 変態点以下
まで空冷、炉冷または水冷等によって冷却する。(Slab Cooling to Temperature Range Below Ar 3 Transformation Point)
As in the present embodiment, the slab for H-section steel is manufactured by continuous casting. A slab immediately after continuous casting has the largest crystal grains. When rolling is started from this state, the ferrite crystal grains eventually become large, and the strength and toughness are reduced accordingly. Therefore, after continuous casting
It is effective to perform slab cooling to a temperature range equal to or lower than the Ar 3 transformation point and then reheat the ferrite to austenite to refine the austenite crystal grains at the beginning of rolling. Therefore, continuous casting slab
It is cooled by air cooling, furnace cooling, water cooling or the like until the austenite transforms to ferrite below the Ar 3 transformation point.
【００３７】Ar3 変態点は、本実施形態では式により
算出した。しかし、適宜手段により実測して求めてもよ
いことはいうまでもない。なお、本実施形態とは異な
り、造塊スラブを用いる場合には、このようなスラブ冷
却工程は不要であることはいうまでもない。In this embodiment, the Ar 3 transformation point is calculated by an equation. However, needless to say, it may be obtained by actual measurement by appropriate means. It is needless to say that, unlike the present embodiment, when using an ingot slab, such a slab cooling step is unnecessary.
【００３８】(Ar3 変態点以下の温度域から1250〜1350
℃への加熱)Ｈ形鋼用圧延機のミル剛性は、厚板用圧延
機のミル剛性に比較すると、非常に小さい。そのため、
スラブ加熱温度が1250℃未満であるとトルクオーバー等
の圧延トラブルを発生し易く、圧下不能の事態を招くお
それがある。また、スラブ加熱温度が1350℃を超える
と、加熱炉の燃料原単位が上昇するのみであって不経済
かつ無意味である。そこで、本発明では、スラブ加熱温
度は1250℃以上1350℃以下と限定する。(1250 to 1350 from the temperature range below the Ar 3 transformation point)
The mill stiffness of the H-section rolling mill is very small as compared with the mill stiffness of the thick plate rolling mill. for that reason,
If the slab heating temperature is lower than 1250 ° C., rolling troubles such as torque over are likely to occur, and there is a possibility that a situation in which reduction is impossible is caused. On the other hand, if the slab heating temperature exceeds 1350 ° C., only the fuel consumption of the heating furnace increases, which is uneconomical and meaningless. Therefore, in the present invention, the slab heating temperature is limited to 1250 ° C. or more and 1350 ° C. or less.
【００３９】なお、本実施形態では、スラブに適量のTi
が含有されているため、この加熱時に、Tiは炭窒化物を
形成し1250〜1350℃の加熱温度においても固溶せずオー
ステナイト結晶粒の粗大化を抑制する。In this embodiment, an appropriate amount of Ti is added to the slab.
During the heating, Ti forms carbonitrides and does not form a solid solution even at a heating temperature of 1250 to 1350 ° C., and suppresses coarsening of austenite crystal grains.
【００４０】(熱間粗圧延)熱間粗圧延は、鋼材の機械的
性能を向上する工程ではなく、鋼材の機械的性能を制御
する次の熱間中間圧延の前段階圧延工程である。通常、
粗ユニバーサル圧延機を用いて複数パスのリバース圧延
が行われて、中間圧延素材である粗形鋼片が得られる。
本発明では、熱間粗圧延は、通常の圧延条件で行えばよ
い。(Rough Hot Rolling) The hot rough rolling is not a step of improving the mechanical performance of the steel material, but a pre-rolling step of the next hot intermediate rolling for controlling the mechanical performance of the steel material. Normal,
Reverse rolling is performed in a plurality of passes using a coarse universal rolling mill, and a coarse shaped billet as an intermediate rolled material is obtained.
In the present invention, hot rough rolling may be performed under normal rolling conditions.
【００４１】(熱間中間圧延)熱間粗圧延を終了した後
に、引き続き、または一旦冷却を行ってから、熱間中間
圧延が行われる。連続して熱間中間圧延を行うほうがエ
ネルギの点で有利であるが、連続して熱間中間圧延を行
うことができない場合には、一旦冷却して再度加熱して
から行ってもよい。(Hot Intermediate Rolling) After the completion of the hot rough rolling, the hot intermediate rolling is carried out continuously or once after cooling. It is advantageous in terms of energy to perform continuous hot intermediate rolling, but if hot intermediate rolling cannot be performed continuously, cooling and heating may be performed once.
【００４２】熱間中間圧延は、粗形鋼片の造形を行って
中間圧延材とするとともに、スラブ加熱時に粗大化した
結晶粒を微細化して適度な強度および靱性を中間圧延材
に与える圧延工程であり、本発明の中心的圧延工程であ
る。The hot intermediate rolling is a rolling step of shaping a coarse billet into an intermediate rolled material, and also providing a moderate strength and toughness to the intermediate rolled material by refining the coarse crystal grains during slab heating. This is the central rolling step of the present invention.
【００４３】この熱間中間圧延工程は、エッジャー圧延
機および粗ユニバーサル圧延機を用いて、複数パスのリ
バース圧延により行われる。この圧延工程においては、
中間圧延材の温度は約100 〜150 ℃低下する。圧延機の
性能およびオーステナイト未再結晶域であることを考慮
した望ましい仕上げ温度は、後述するように、850 〜75
0 ℃である。This hot intermediate rolling step is performed by reverse rolling in a plurality of passes using an edger rolling mill and a rough universal rolling mill. In this rolling process,
The temperature of the intermediate rolled material drops by about 100 to 150 ° C. A desirable finishing temperature in consideration of the rolling mill performance and the austenite unrecrystallized region is 850 to 75, as described later.
0 ° C.
【００４４】よって、熱間中間圧延の圧延開始温度は、
950 ℃以下とする。圧延開始温度が950 ℃超であると、
圧延終了時にオーステナイトの再結晶・粗大化のため、
微細化させたオーステナイト結晶粒が粗大化し、さらに
圧延中に導入した変形帯も減少することからフェライト
結晶核が減少し微細フェライトを得ることができなくな
る。一方、圧延開始温度が900 ℃未満であると、極厚Ｈ
形鋼の場合には圧延終了時に圧延不可能な750 ℃未満の
温度域まで低下する。そこで、本発明では、熱間中間圧
延の圧延開始温度は、950 ℃以下900 ℃以上と限定す
る。Therefore, the rolling start temperature of the hot intermediate rolling is:
950 ° C or less. If the rolling start temperature is over 950 ° C,
At the end of rolling, due to recrystallization and coarsening of austenite,
Since the refined austenite crystal grains are coarsened and the deformation bands introduced during rolling are also reduced, ferrite crystal nuclei are reduced, and it is not possible to obtain fine ferrite. On the other hand, if the rolling start temperature is less than 900 ° C.,
In the case of shaped steel, the temperature drops to a temperature range below 750 ° C where rolling cannot be performed at the end of rolling. Therefore, in the present invention, the rolling start temperature of the hot intermediate rolling is limited to 950 ° C or lower and 900 ° C or higher.
【００４５】また、Ar3 変態点以上のオーステナイト未
再結晶温度域、すなわち850 ℃以下750 ℃以上の温度域
における総圧下率が35％未満であると、所望の強度およ
び靱性がいずれも得られない。そこで、本発明では、Ar
3 変態点以上のオーステナイト未再結晶温度域における
総圧下率を35％以上と限定する。これら以外の熱間中間
圧延条件に関する限定は、不要である。If the total rolling reduction is less than 35% in the austenite non-recrystallization temperature range of not less than the Ar 3 transformation point, that is, 850 ° C. or less and 750 ° C. or more, both desired strength and toughness can be obtained. Absent. Therefore, in the present invention, Ar
The total rolling reduction in the austenite non-recrystallization temperature range of 3 transformation points or more is limited to 35% or more. There is no need to limit other hot intermediate rolling conditions.
【００４６】(熱間仕上げ圧延)熱間仕上げ圧延は、仕上
ユニバーサル圧延機により通常１パスの圧延により行わ
れ、熱間粗圧延後のＨ形鋼の形状を整える最終圧延工程
である。この熱間仕上げ圧延では、フランジの寸法修正
等が行われる程度であって圧下は殆ど行われない。仕上
ユニバーサル圧延機の性能を勘案し、仕上げ温度は熱間
中間圧延と同様に850 ℃以下750 ℃以下が望ましい。(Hot Finish Rolling) The hot finish rolling is usually performed by one-pass rolling by a finishing universal rolling mill, and is a final rolling step for adjusting the shape of the H-section steel after the hot rough rolling. In this hot finishing rolling, the dimension of the flange is corrected, and the rolling is hardly performed. In consideration of the performance of the finishing universal rolling mill, the finishing temperature is desirably 850 ° C or lower and 750 ° C or lower as in the case of hot intermediate rolling.
【００４７】(室温までの放冷)熱間仕上圧延後の冷却過
程で変態したフェライトは、時間の経過とともにその結
晶粒が成長して粗大化するが、圧延工程での圧下により
ミクロ組織は充分に微細化されているため、最終的に得
られるフェライト結晶粒も微細なものとなり、放冷によ
り充分な靱性が確保される。むしろ、加速冷却等を施す
と冷却むらが発生し機械的性質にばらつきを生じてしま
う。そこで、熱間仕上圧延後の冷却は、放冷により、行
う。(Cooling to room temperature) The ferrite transformed in the cooling process after hot finish rolling grows its crystal grains with the passage of time and becomes coarse, but the microstructure is sufficiently reduced by the rolling in the rolling process. The ferrite crystal grains finally obtained are also fine, and sufficient toughness is ensured by cooling. Rather, when accelerated cooling or the like is performed, uneven cooling occurs, causing variations in mechanical properties. Therefore, cooling after hot finish rolling is performed by cooling.
【００４８】このように、本発明にかかる極厚形鋼の製
造法によれば、組成の最適化により溶接性が確保され、
Ti添加によって1250〜1350℃の高温加熱時のオーステナ
イト結晶粒の粗大化が防止され、NbおよびＶの複合添加
によりAr3 変態点以上の温度域で圧延される際のオース
テナイト結晶粒微細化と、Nb炭窒化物およびＶ炭窒化物
の析出による析出強化とが図られる。As described above, according to the method of manufacturing an extremely thick section steel according to the present invention, the weldability is ensured by optimizing the composition,
The addition of Ti prevents coarsening of austenite crystal grains during high-temperature heating at 1250 to 1350 ° C, and refinement of austenite crystal grains when rolled in a temperature range above the Ar 3 transformation point by the combined addition of Nb and V; Precipitation strengthening by precipitation of Nb carbonitride and V carbonitride is achieved.
【００４９】このようにして、本発明によれば、設備増
設を行うことなく、溶接性、強度および靱性に優れた極
厚Ｈ形鋼を、熱処理を行うことなく、製造することがで
きる。具体的には、降伏点：325 〜445 N/mm2 、引張強
さ：490 〜610 N/mm2 、伸び：23％以上、０℃Ｖノッチ
シャルピー吸収エネルギー：100 Ｊ以上である、板厚が
40mm以上の50キロ級極厚Ｈ形鋼を、熱処理を行うことな
く、製造することができる。As described above, according to the present invention, an extremely thick H-section steel excellent in weldability, strength and toughness can be manufactured without heat treatment without additional facilities. Specifically, the yield point: 325 ~445 N / mm 2, tensile strength: 490 ~610 N / mm 2, elongation: 23% or more, 0 ° C. V notch Charpy absorbed energy: at 100 J or more, the thickness But
It is possible to manufacture a 50 kg class thick H-section steel of 40 mm or more without heat treatment.
【００５０】[0050]
【実施例】さらに、本発明を実施例を参照しながら、よ
り具体的に説明する。表１に示す鋼組成を有する連続鋳
造スラブを、連続鋳造終了後に室温まで空冷し、1250〜
1350℃の温度域に再加熱を行って、熱間粗圧延を行って
粗形鋼片とした。なお、1400℃まで加熱すると、融点近
傍であるために熱間粗圧延時に素材がロールに焼付いて
しまい、圧延は困難であった。EXAMPLES The present invention will be described more specifically with reference to examples. The continuous cast slab having the steel composition shown in Table 1 was air-cooled to room temperature after the end of the continuous cast, and
Reheating was performed to a temperature range of 1350 ° C., and hot rough rolling was performed to obtain a coarse shaped slab. In addition, when heated to 1400 ° C., the material was seized on the roll during hot rough rolling because the temperature was near the melting point, and rolling was difficult.
【００５１】[0051]
【表１】 [Table 1]
【００５２】熱間粗圧延温度は1300℃であった。そし
て、この粗形鋼片に熱間中間圧延を行った。熱間中間圧
延における圧延開始温度、圧延終了温度およびAr3 変態
点以上のオーステナイト未再結晶温度域における総圧下
率は、表２に示す。The hot rough rolling temperature was 1300 ° C. Then, hot intermediate rolling was performed on the crude steel slab. Table 2 shows the rolling start temperature, the rolling end temperature, and the total rolling reduction in the austenite non-recrystallization temperature range equal to or higher than the Ar 3 transformation point in hot intermediate rolling.
【００５３】[0053]
【表２】 [Table 2]
【００５４】そして、熱間仕上げ圧延を行い、その後室
温まで放冷することにより、試料No.1〜試料No.24 の極
厚溝形鋼を得た。この極厚溝形鋼の寸法は、フランジ幅
303mm、ウェブ幅606 mm、フランジ厚さ50mm、ウェブ厚
さ50mmであった。Then, hot finish rolling was performed, and then the steel was allowed to cool to room temperature, thereby obtaining extremely thick channel steels of Sample Nos. 1 to 24. The dimensions of this thick channel are the flange width
The thickness was 303 mm, the web width was 606 mm, the flange thickness was 50 mm, and the web thickness was 50 mm.
【００５５】これらの溝形鋼のフランジ部の板厚中央部
から、JIS Z 2201 1A の引張試験片とJIS Z 2202 4号の
シャルピー衝撃試験片とを切り出し、YP、TS、ELおよび
vE0を測定した。結果を表２にあわせて示す。A tensile test piece of JIS Z 2201 1A and a Charpy impact test piece of JIS Z 220224 were cut out from the center of the thickness of the flange portion of these channel steels, and were subjected to YP, TS, EL and
vE 0 was measured. The results are shown in Table 2.
【００５６】表２に示すように、本発明の範囲を全て満
足する条件で製造された試料No.1〜試料No. 18は、50キ
ロ級の強度を確保し、靱性もvEO で100 Ｊ以上を確保す
ることができた。また、これらは、炭素当量Ceq.が0.32
〜0.40％の間にあり、溶接性も優れることが確認され
た。As shown in Table 2, the samples No. 1 to No. 18 manufactured under the conditions satisfying the entire range of the present invention ensure a strength of 50 kg class and have a toughness of 100 J or more in vEO. Was able to secure. These have a carbon equivalent Ceq. Of 0.32.
0.40.40%, confirming that the weldability is also excellent.
【００５７】これに対し、試料No.19 はＣ含有量が本発
明の範囲の下限を下回り、試料No.20 はSi含有量が本発
明の範囲を下回り、試料No.21 はMn含有量が本発明の範
囲を下回り、試料No.22 は、NbおよびＶがともに本発明
の範囲を下回っている。そのため、試料No.19 〜試料N
o.22 はいずれも強度が不足し、試料No.19 、21、22は
溶接性も劣化した。In contrast, Sample No. 19 had a C content below the lower limit of the range of the present invention, Sample No. 20 had a Si content below the range of the present invention, and Sample No. 21 had a Mn content of below. Sample No. 22 has Nb and V which are below the range of the present invention. Therefore, sample No. 19 to sample N
Sample Nos. 19, 21, and 22 also had poor weldability with o.22 lacking strength.
【００５８】また、試料No.23 および試料No. 24は、と
もにＣ含有量が本発明の範囲を上回っているため、強度
を確保できたが靱性が著しく劣化した。また、確認のた
め、試料No.5について、熱間中間圧延における圧延開始
温度、終了温度および総圧下率が、表３に示すように本
発明の範囲を満足しない条件に置換して、試料を製造
し、得られた試料のYP、TS、ELおよびvE0 を測定した。
結果を表３にあわせて示す。Further, in Sample No. 23 and Sample No. 24, since the C content exceeded the range of the present invention, the strength was secured, but the toughness was significantly deteriorated. Further, for confirmation, for sample No. 5, the rolling start temperature, end temperature and total draft in hot intermediate rolling were changed to conditions not satisfying the range of the present invention as shown in Table 3, and the sample was replaced with YP, TS, EL and vE 0 of the manufactured and obtained sample were measured.
The results are shown in Table 3.
【００５９】[0059]
【表３】 [Table 3]
【００６０】表３から、本発明により特定された圧延条
件、特に熱間中間圧延条件の有効性が明らかである。Table 3 clearly shows the effectiveness of the rolling conditions specified by the present invention, particularly the hot intermediate rolling conditions.
【００６１】[0061]
【発明の効果】以上、詳細に説明したように、本発明に
より、設備増設することなく、溶接性、強度および靱性
に優れた極厚形鋼を、熱処理を行うことなく、製造する
こと、具体的には、降伏点：325 〜445 N/mm2 、引張強
さ：490 〜610 N/mm2 、伸び：23％以上、０℃Ｖノッチ
シャルピー吸収エネルギー：100 Ｊ以上である、板厚が
40mm以上の柱材用50キロ級極厚形鋼を、熱処理を行うこ
となく、製造することが可能となった。かかる効果を有
する本発明の意義は、極めて著しい。As described in detail above, according to the present invention, it is possible to manufacture an ultra-thick steel having excellent weldability, strength and toughness without heat treatment without additional facilities. specifically, the yield point: 325 ~445 N / mm 2, tensile strength: 490 ~610 N / mm 2, elongation: 23% or more, 0 ° C. V notch Charpy absorbed energy: at 100 J or more, the thickness
It is now possible to produce 50kg-class ultra-thick section steel for column materials of 40mm or more without heat treatment. The significance of the present invention having such an effect is extremely remarkable.
Claims (2)
〜0.55％、Mn：1.00〜1.90％、Ｐ：0.020 ％以下、Ｓ：
0.008 ％以下、Cu：1.00％以下、Nb：0.020〜0.050
％、Ｖ：0.050 〜0.100 ％、Ti：0.010 〜0.030 ％、so
l.Al：0.005 〜0.030 ％、Ｎ：0.003 〜0.005 ％、残部
Feおよび不可避不純物からなる鋼組成を有し、下記式に
より規定される炭素当量Ceq.が0.34〜0.40％であるスラ
ブを、Ar3 変態点以下の温度域から1250〜1350℃へ加熱
して熱間粗圧延を行い、950 〜900 ℃の温度域で熱間中
間圧延を開始し、Ar3 変態点以上のオーステナイト未再
結晶温度域までに総圧下率が35％以上となるように熱間
中間圧延を行い、さらに熱間仕上げ圧延を行い、その後
室温まで放冷することを特徴とする溶接性、強度および
靱性に優れた極厚形鋼の製造法。 Ceq(%)＝C(%)+Si/24(%)+Mn/6(%)+Ni/40(%)+Cr/5(%)+Mo/
4(%)+V/14(%)C .: 0.05 to 0.12% by weight, Si: 0.05% by weight
~ 0.55%, Mn: 1.00 ~ 1.90%, P: 0.020% or less, S:
0.008% or less, Cu: 1.00% or less, Nb: 0.020 to 0.050
%, V: 0.050 to 0.100%, Ti: 0.010 to 0.030%, so
l.Al: 0.005 to 0.030%, N: 0.003 to 0.005%, balance
A slab having a steel composition comprising Fe and unavoidable impurities and having a carbon equivalent Ceq. Defined by the following formula of 0.34 to 0.40% is heated from a temperature range of not more than the Ar 3 transformation point to 1250 to 1350 ° C. Intermediate rough rolling is performed, and hot intermediate rolling is started in a temperature range of 950 to 900 ° C., and a hot rolling is performed so that a total reduction ratio becomes 35% or more by an austenite non-recrystallization temperature range not lower than an Ar 3 transformation point. A method for producing an ultra-thick section steel having excellent weldability, strength and toughness, characterized by rolling, hot finishing rolling, and then cooling to room temperature. Ceq (%) = C (%) + Si / 24 (%) + Mn / 6 (%) + Ni / 40 (%) + Cr / 5 (%) + Mo /
4 (%) + V / 14 (%)
〜0.55％、Mn：1.00〜1.90％、Ｐ：0.020 ％以下、Ｓ：
0.008 ％以下、Cu：1.00％以下、Nb：0.020〜0.050
％、Ｖ：0.050 〜0.100 ％、Ti：0.005 〜0.030 ％、so
l.Al：0.005 〜0.050 ％、Ｎ：0.001 〜0.005 ％、残部
Feおよび不可避不純物からなる鋼組成を有し、下記式に
より規定される炭素当量Ceq.が0.32〜0.40％であるスラ
ブを、Ar3 変態点以下の温度域から1250〜1350℃へ加熱
して熱間粗圧延を行い、950 〜900 ℃の温度域で熱間中
間圧延を開始し、Ar3 変態点以上のオーステナイト未再
結晶温度域までに総圧下率が35％以上となるように熱間
中間圧延を行い、さらに熱間仕上げ圧延を行い、その後
室温まで放冷することを特徴とする溶接性、強度および
靱性に優れた極厚形鋼の製造法。 Ceq(%)＝C(%)+Si/24(%)+Mn/6(%)+Ni/40(%)+Cr/5(%)+Mo/
4(%)+V/14(%)2. C: 0.05 to 0.12% by weight, Si: 0.05% by weight
~ 0.55%, Mn: 1.00 ~ 1.90%, P: 0.020% or less, S:
0.008% or less, Cu: 1.00% or less, Nb: 0.020 to 0.050
%, V: 0.050 to 0.100%, Ti: 0.005 to 0.030%, so
l.Al: 0.005 to 0.050%, N: 0.001 to 0.005%, balance
A slab having a steel composition composed of Fe and unavoidable impurities and having a carbon equivalent Ceq. Defined by the following formula of 0.32 to 0.40% is heated from a temperature range not higher than the Ar 3 transformation point to 1250 to 1350 ° C. Intermediate rough rolling is performed, and hot intermediate rolling is started in a temperature range of 950 to 900 ° C., and a hot rolling is performed so that a total reduction ratio becomes 35% or more by an austenite non-recrystallization temperature range not lower than an Ar 3 transformation point. A method for producing an ultra-thick section steel having excellent weldability, strength and toughness, characterized by rolling, hot finishing rolling, and then cooling to room temperature. Ceq (%) = C (%) + Si / 24 (%) + Mn / 6 (%) + Ni / 40 (%) + Cr / 5 (%) + Mo /
4 (%) + V / 14 (%)
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|---|---|---|---|
| JP05109399A JP3589071B2 (en) | 1998-03-24 | 1999-02-26 | Manufacturing method of ultra-thick section steel with excellent weldability, strength and toughness |
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|---|---|---|---|
| JP7604798 | 1998-03-24 | ||
| JP10-76047 | 1998-03-24 | ||
| JP05109399A JP3589071B2 (en) | 1998-03-24 | 1999-02-26 | Manufacturing method of ultra-thick section steel with excellent weldability, strength and toughness |
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| Publication Number | Publication Date |
|---|---|
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|---|---|---|---|
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| Country | Link |
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