JPH05331538A - Manufacture of thick high toughness and high tensile strength steel plate excellent in toughness on central part of plate thickness - Google Patents
Manufacture of thick high toughness and high tensile strength steel plate excellent in toughness on central part of plate thicknessInfo
- Publication number
- JPH05331538A JPH05331538A JP16535292A JP16535292A JPH05331538A JP H05331538 A JPH05331538 A JP H05331538A JP 16535292 A JP16535292 A JP 16535292A JP 16535292 A JP16535292 A JP 16535292A JP H05331538 A JPH05331538 A JP H05331538A
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- Prior art keywords
- toughness
- rolling
- less
- temperature
- plate thickness
- 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.)
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は板厚中央部の靭性の優れ
た厚肉高靭性高張力鋼板の製造方法に関し、さらに詳し
くは、板厚中央部の靭性が優れている板厚が８０ｍｍ以
上の厚肉高靭性高張力鋼板の製造方法に関するものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a thick, high-toughness, high-strength steel sheet having excellent toughness in the central portion of plate thickness, and more specifically, a plate having excellent toughness in the central portion of plate thickness of 80 mm or more. The present invention relates to a method for producing a thick, high toughness, high strength steel sheet.
【０００２】[0002]
【従来技術】一般に、氷海域海洋構造物に使用される鋼
板には、溶接時に予熱が不要で、かつ、低温靭性の優れ
た高強度の板厚８０ｍｍ以上の厚肉鋼板を要求されてい
る。2. Description of the Related Art Generally, a steel plate used for an ice structure in an offshore sea is required to be a thick steel plate having a thickness of 80 mm or more that does not require preheating during welding and has excellent low temperature toughness.
【０００３】このような鋼板の製造には、板厚中央部の
靭性向上のための低温圧延および炭素当量の低減が可能
な加速冷却法を適用することが有効であることは、既に
よく知られているところである。It is already well known that it is effective to apply low temperature rolling for improving the toughness of the central portion of the sheet thickness and accelerated cooling method capable of reducing the carbon equivalent to the production of such a steel sheet. It's about to come.
【０００４】しかし、板厚中央部の靭性向上のために従
来行われている低温圧延に関しては、板厚中央部におい
てオーステナイト未再結晶温度域における相当量の圧下
を行う必要があるが、圧延中に計測或いは制御される温
度が鋼板表面温度であり、板厚中央部の温度ではないこ
と、さらに、圧延パス間時間については全く考慮されて
いないことにより、必ずしも安定して板厚中央部の靭性
の優れた厚肉鋼板を製造することはできなかった。However, in the low temperature rolling conventionally performed to improve the toughness of the central portion of the sheet thickness, it is necessary to carry out a considerable amount of reduction in the austenite unrecrystallized temperature region in the central portion of the sheet thickness. Since the temperature measured or controlled in the above is the steel plate surface temperature, not the temperature at the center of the plate thickness, and the time between rolling passes is not considered at all, the toughness at the center of the plate thickness is not always stable. It was not possible to manufacture an excellent thick steel plate of
【０００５】[0005]
【発明が解決しようとする課題】本発明は上記に説明し
た板厚中央部の靭性の良好な厚肉鋼板の製造方法の従来
技術の問題点に鑑み、本発明者が鋭意研究を行い検討を
重ねた結果、圧延パラメータと厚肉鋼板の板厚中央部の
靭性とに良好な相関関係のあることを知見し、圧延パラ
メータを利用して板厚中央部の靭性の優れた板厚が８０
ｍｍ以上の厚肉高靭性高張力鋼板の製造方法を開発した
のである。DISCLOSURE OF THE INVENTION In view of the problems of the prior art of the method for manufacturing a thick steel plate having good toughness in the central portion of the plate thickness described above, the present inventor has conducted earnest research and studied. As a result of stacking, it was found that there is a good correlation between the rolling parameter and the toughness of the thick central portion of the thick steel plate, and the rolling parameter is used to obtain a plate thickness with excellent toughness of the central portion of 80
We have developed a method for manufacturing thick, high-toughness, high-strength steel plates with a thickness of mm or more.
【０００６】[0006]
【課題を解決するための手段】本発明に係る板厚中央部
の靭性の優れた厚肉高靭性高張力高張力の製造方法は、
Ｃ ０.０１〜０.１０ｗｔ％、Ｓｉ ０.１０〜０.５
０ｗｔ％、Ｍｎ ０.５〜２.０ｗｔ％、Ｐ ０．０１０
ｗｔ％以下、Ｓ ０.００３ｗｔ％以下、Ａｌ ０.０１
０〜０.１００ｗｔ％ Ｎｂ ０.００３〜０.０３０ｗｔ％、Ｔｉ ０.００５
〜０.０２０ｗｔ％、Ｎ ０.００２０〜０.００６０ｗ
ｔ％を含有し、残部Ｆｅおよび不可避不純物からなる鋼
を、Ａｃ3以上、１０００℃以下の温度に加熱後、差分
法を用いて計算される板厚中央部の温度｛Ｔ(ｔ／２)｝
が８５０〜９００℃、圧下量２０％以上の粗圧延を行
い、その後、板厚中央部の温度｛Ｔ(ｔ／２)｝がＡｒ3
以上、８００℃以下の温度で、圧下量３０％以上の仕上
げ圧延を行い、直ちに、鋼板表面温度が５００℃以下の
温度域まで１〜１０℃／ｓｅｃの冷却速度により冷却を
行い、圧延パラメーターＤが１０以下になるように圧延
条件を制御することを特徴とする板厚中央部の靭性の優
れた厚肉高靭性高張力鋼板の製造方法を第１の発明と
し、Ｃ ０.０１〜０.１０ｗｔ％、Ｓｉ ０.１０〜０.
５０ｗｔ％、Ｍｎ ０.５〜２.０ｗｔ％、Ｐ ０．０１
０ｗｔ％以下、Ｓ ０.００３ｗｔ％以下、Ａｌ ０.０
１０〜０.１００ｗｔ％ Ｎｂ ０.００３〜０.０３０ｗｔ％、Ｔｉ ０.００５
〜０.０２０ｗｔ％、Ｎ ０.００２０〜０.００６０ｗ
ｔ％を含有し、さらに、Ｃｕ １.５ｗｔ％以下、Ｎｉ
３.０ｗｔ％以下、Ｃａ ０.００５０ｗｔ％以下の中
から選んだ１種または２種以上を含有し、残部Ｆｅおよ
び不可避不純物からなる鋼を、Ａｃ3以上、１０００℃
以下の温度に加熱後、差分法を用いて計算される板厚中
央部の温度｛Ｔ(ｔ／２)｝が８５０〜９００℃、圧下量
２０％以上の粗圧延を行い、その後、板厚中央部の温度
｛Ｔ(ｔ／２)｝がＡｒ3以上、８００℃以下の温度で、
圧下量３０％以上の仕上げ圧延を行い、直ちに、鋼板表
面温度が５００℃以下の温度域まで１〜１０℃／ｓｅｃ
の冷却速度により冷却を行い、圧延パラメーターＤが１
０以下になるように圧延条件を制御することを特徴とす
る板厚中央部の靭性の優れた厚肉高靭性高張力鋼板の製
造方法を第２の発明とする２つの発明よりなるものであ
る。The method for producing thick-walled high toughness high tensile strength high tensile strength of the central portion of the plate thickness according to the present invention is as follows.
C 0.01 to 0.10 wt%, Si 0.10 to 0.5
0 wt%, Mn 0.5 to 2.0 wt%, P 0.010
wt% or less, S 0.003 wt% or less, Al 0.01
0 to 0.100 wt% Nb 0.003 to 0.030 wt%, Ti 0.005
~ 0.020wt%, N 0.0020 ~ 0.0060w
After heating the steel containing t% and the balance Fe and unavoidable impurities to a temperature of Ac 3 or more and 1000 ° C. or less, the temperature of the central portion of the plate thickness calculated using the difference method {T (t / 2) }
Of 850 to 900 ° C. and a rolling reduction of 20% or more, and then the temperature at the center of the plate thickness {T (t / 2)} is Ar 3
As described above, finish rolling with a rolling reduction of 30% or more is performed at a temperature of 800 ° C. or less, and immediately, the steel sheet surface temperature is cooled to a temperature range of 500 ° C. or less at a cooling rate of 1 to 10 ° C./sec. Is controlled to be 10 or less, the first invention is a method for producing a thick, high-toughness, high-strength steel sheet having excellent toughness in the central portion of the sheet thickness, and C 0.01 to 0. 10 wt%, Si 0.10 to 0.1.
50 wt%, Mn 0.5-2.0 wt%, P 0.01
0 wt% or less, S 0.003 wt% or less, Al 0.0
10 to 0.100 wt% Nb 0.003 to 0.030 wt%, Ti 0.005
~ 0.020wt%, N 0.0020 ~ 0.0060w
t%, Cu 1.5 wt% or less, Ni
Steel containing 1 or 2 or more kinds selected from 3.0 wt% or less and Ca 0.0050 wt% or less, and the balance Fe and unavoidable impurities is Ac 3 or more and 1000 ° C.
After heating to the following temperature, the temperature {T (t / 2)} of the central part of the plate thickness calculated using the difference method is 850 to 900 ° C., and rough rolling is performed with a reduction of 20% or more, and then the plate thickness When the temperature of the central part {T (t / 2)} is above Ar 3 and below 800 ° C.,
Finishing rolling with a reduction amount of 30% or more is immediately performed until the steel plate surface temperature reaches a temperature range of 500 ° C or less at 1 to 10 ° C / sec.
The rolling parameter D is 1
A second aspect of the present invention is a method for producing a thick and high-toughness high-strength steel sheet having excellent toughness in the central portion of the sheet thickness, which is characterized by controlling rolling conditions so as to be 0 or less. ..
【０００７】本発明に係る板厚中央部の靭性の優れた厚
肉高靭性高張力鋼板の製造方法について、以下具体的に
説明する。先ず、本発明に係る板厚中央部の靭性の優れ
た厚肉高靭性高張力鋼板の製造方法において、使用する
鋼の含有成分および成分割合について説明する。The method for producing a thick, high-toughness, high-strength steel sheet having excellent toughness in the central portion of the sheet thickness according to the present invention will be specifically described below. First, in the method for producing a thick, high-toughness, high-strength steel sheet having excellent toughness in the central portion of the plate thickness according to the present invention, the contained components and component ratios of the steel used will be described.
【０００８】Ｃは強度上昇に有効な元素であり、含有量
が０.０１ｗｔ％未満ではこの効果は期待てきず、ま
た、０.１０ｗｔ％を越えて含有させると優れた靭性を
得ることができず、さらに、耐溶接割れ性が低下するよ
うになる。よって、Ｃ含有量は０.０１〜０.１０ｗｔ％
とする。C is an element effective for increasing the strength, and if the content is less than 0.01 wt%, this effect cannot be expected, and if it exceeds 0.10 wt%, excellent toughness can be obtained. In addition, the weld crack resistance is further reduced. Therefore, the C content is 0.01 to 0.10 wt%
And
【０００９】Ｓｉは脱酸元素であり、含有量が０.１０
ｗｔ％未満ではこの効果は少なく、また、０.５０ｗｔ
％を越えて過剰に含有させると靭性を劣化させる。よつ
て、Ｓｉ含有量は０.１０〜０.５０ｗｔ％とする。Si is a deoxidizing element, and its content is 0.10.
If it is less than wt%, this effect is small, and 0.50 wt%
If it is contained excessively in excess of%, the toughness deteriorates. Therefore, the Si content is set to 0.10 to 0.50 wt%.
【００１０】Ｍｎは強度上昇に有効な元素であり、含有
量が０.５ｗｔ％未満ではこの効果は期待できず、ま
た、２.０ｗｔ％を越えて含有させると靭性を劣化させ
る。よって、Ｍｎ含有量は０.５〜２.０ｗｔ％ｗｔ％と
する。Mn is an element effective for increasing the strength, and if the content is less than 0.5 wt%, this effect cannot be expected, and if it exceeds 2.0 wt%, the toughness deteriorates. Therefore, the Mn content is set to 0.5 to 2.0 wt% wt%.
【００１１】Ｐは偏析傾向が強く、母材および溶接部の
靭性を劣化させる元素であり、含有量は極力低く抑制す
る必要がある。従って、Ｐ含有量は０.０１０ｗｔ％以
下に規制する。P is an element that has a strong tendency to segregate and deteriorates the toughness of the base material and the welded portion, and its content must be suppressed as low as possible. Therefore, the P content is limited to 0.010 wt% or less.
【００１２】ＳはＡ系介在物を形成し、板厚方向の絞り
特性、耐ラメラーティアー特性、さらに、靭性を劣化さ
せる元素であり、そのため、Ｓ含有量は極力低く抑制す
る必要がある。よって、Ｓ含有量は０.００３ｗｔ％以
下に規制する。S is an element that forms an A type inclusion and deteriorates the drawing property in the plate thickness direction, the anti-lamellar tear property, and the toughness. Therefore, the S content must be suppressed as low as possible. Therefore, the S content is restricted to 0.003 wt% or less.
【００１３】Ａｌは脱酸元素であり、含有量が０.０１
０ｗｔ％未満では脱酸効果は期待できず、また、０.１
００ｗｔ％を越えて含有させると介在物を形成し、靭性
を劣化させる。よって、Ａｌ含有量は０.０１０〜０.１
００ｗｔ％とする。Al is a deoxidizing element and its content is 0.01.
If it is less than 0 wt%, the deoxidizing effect cannot be expected, and 0.1
If it exceeds 0.00 wt%, inclusions are formed and the toughness deteriorates. Therefore, the Al content is 0.010 to 0.1
It is set to 00 wt%.
【００１４】Ｎｂは固溶状態においてオーステナイの再
結晶を抑制し、制御圧延の効果を高くし、さらに、圧延
後の加速冷却による変態強化を促進して強度および靭性
の向上に寄与する元素であり、含有量が０.００３ｗｔ
％未満ではこのような効果は期待できず、また、０.０
３０ｗｔ％を越えて過剰に含有させると溶接部の靭性を
劣化させる。よって、Ｎｂ含有量は０.００３〜０.０３
０ｗｔ％とする。Nb is an element that suppresses recrystallization of austenite in a solid solution state, enhances the effect of controlled rolling, and further promotes transformation strengthening by accelerated cooling after rolling to contribute to improvement of strength and toughness. , Content 0.003wt
If it is less than%, such an effect cannot be expected, and it is 0.0
If the content exceeds 30 wt% and is excessive, the toughness of the welded portion deteriorates. Therefore, the Nb content is 0.003 to 0.03.
It is set to 0 wt%.
【００１５】Ｔｉは難溶性の炭窒化物を形成し、スラブ
加熱時または溶接時のオーステナイ粒の成長を抑制する
ので、母材および溶接部の靭性を向上させる元素であ
り、含有量が０.００５ｗｔ％未満ではこのような効果
を期待することができず、また、０.０２０ｗｔ％を越
えて含有させると粗大な介在物を形成し、靭性を劣化さ
せる。よって、Ｔｉ含有量は０.００５〜０.０２０ｗｔ
％とする。Ti forms an insoluble carbonitride and suppresses the growth of austenite grains during slab heating or welding. Therefore, Ti is an element that improves the toughness of the base material and the welded portion, and its content is 0. If it is less than 005 wt%, such an effect cannot be expected, and if it exceeds 0.020 wt%, coarse inclusions are formed and the toughness is deteriorated. Therefore, the Ti content is 0.005 to 0.020 wt.
%.
【００１６】ＮはＴｉと難溶性の炭窒化物を形成し、母
材および溶接部の靭性を向上させる元素であり、含有量
が０.００２０ｗｔ％未満ではこの効果を期待すること
ができず、また、０.００６０ｗｔ％を越えて過剰に含
有させると母材および溶接部の靭性を著しく劣化させ
る。よって、Ｎ含有量は０.００２０〜０.００６０ｗｔ
％とする。N is an element that forms a carbonitride that is hardly soluble with Ti and improves the toughness of the base material and the welded portion. If the content is less than 0.0020 wt%, this effect cannot be expected. Further, if the content exceeds 0.0060 wt% and is excessively contained, the toughness of the base material and the welded portion is significantly deteriorated. Therefore, the N content is 0.0020 to 0.0060 wt.
%.
【００１７】上記の各元素を必須成分とするのである
が、Ｃｕ、Ｎｉ、Ｃａの１種または２種以上を含有させ
ることも可能である。Each of the above elements is an essential component, but it is also possible to contain one or more of Cu, Ni and Ca.
【００１８】Ｃｕは固溶強化、析出強化或いは焼入れ性
向上により変態強化に有効な元素であり、過剰に含有さ
せると靭性を劣化させる。よって、Ｃｕ含有量は１.５
ｗｔ％以下とする。Cu is an element effective for strengthening transformation by solid solution strengthening, precipitation strengthening or improving hardenability, and if contained in excess, it deteriorates toughness. Therefore, the Cu content is 1.5
Wt% or less.
【００１９】Ｎｉは低温靭性を改善する元素であり、過
剰に含有させてもそれ程効果の向上を期待できないと同
時に高価である。よって、Ｎｉ含有量は３.０ｗｔ％以
下とする。Ni is an element that improves the low temperature toughness, and even if it is contained excessively, the effect cannot be expected to be improved so much and at the same time it is expensive. Therefore, the Ni content is set to 3.0 wt% or less.
【００２０】Ｃａは靭性を改善する元素であり、過剰の
含有は逆に靭性を損なう。よって、Ｃａ含有量は０.０
０５０ｗｔ％以下とする。Ca is an element that improves toughness, and excessive inclusion adversely affects toughness. Therefore, the Ca content is 0.0
It is 050 wt% or less.
【００２１】次に、本発明に係る板厚中央部の靭性の優
れた厚肉高靭性高張力鋼板の製造方法について説明す
る。Next, a method for manufacturing a thick, high-toughness, high-strength steel sheet having excellent toughness in the central portion of the sheet thickness according to the present invention will be described.
【００２２】圧延の前工程において加熱を行うのである
が、この加熱は鋳片を完全にオーステナイ化する必要が
あり、加熱温度がＡｃ3未満の温度では完全なオーステ
ナイ化が達成できず、また、１０００℃を越える高い加
熱温度ではオーステナイ粒が粗大化して、靭性の劣化を
招来するようになる。よつて、加熱温度はＡｃ3以上、
１０００℃以下とする。Heating is carried out in the pre-rolling step, but this heating needs to completely austenize the slab, and if the heating temperature is less than Ac 3 , complete austenization cannot be achieved, and At a high heating temperature exceeding 1000 ° C., the austenite grains are coarsened and the toughness is deteriorated. Therefore, the heating temperature is Ac 3 or higher,
It shall be 1000 ° C or lower.
【００２３】上記の加熱温度に加熱された鋳片を熱間圧
延するに際して、特定の圧延温度域における圧下量を制
御する必要があり、厚肉鋼板の板厚中央部の靭性の向上
には、板厚中央部におけるオーステナイ再結晶温度域に
おける圧下およびオーステナイ未再結晶温度域における
圧下を行うことが重要である。When hot rolling the slab heated to the above heating temperature, it is necessary to control the amount of reduction in a specific rolling temperature range, and in order to improve the toughness of the central portion of the thick steel plate, It is important to carry out reduction in the austenite recrystallization temperature region in the central part of the plate thickness and reduction in the austenite non-recrystallization temperature region.
【００２４】そして、板厚中央部の温度が８５０〜９０
０℃は、オーステナイ再結晶温度域、および、Ａｒ3以
上、８００℃以下の温度は未再結晶温度域に相当してお
り、そして、−６０℃以下のシャルピー破面遷移温度を
保持するためには、板厚中央部の温度が８５０〜９００
℃の温度域においては、圧下量を２０％以上の粗圧延を
行う必要があり、また、Ａｒ3以上、８００℃以下の温
度域においては３０％以上の圧下量としなければならな
い。The temperature at the center of the plate thickness is 850-90.
0 ° C. corresponds to the austenite recrystallization temperature range, and the temperature of Ar 3 to 800 ° C. corresponds to the non-recrystallization temperature range, and in order to maintain the Charpy fracture surface transition temperature of −60 ° C. or lower. Has a temperature of 850 to 900 in the central part of the plate thickness.
In the temperature range of ° C, it is necessary to carry out rough rolling with a reduction amount of 20% or more, and with a reduction amount of 30% or more in the temperature region of Ar 3 or more and 800 ° C or less.
【００２５】しかして、上記の場合において、それぞれ
の温度は差分法を用いて計算された板厚中央部の温度で
なければならず、これは、通常の制御圧延において管理
される鋼板表面温度は、厚肉鋼板の場合には、板厚中央
部の温度と相関がなく、オーステナイ再結晶、未再結晶
における圧下量を精度よく制御する指標にならないから
である。In the above case, however, each temperature must be the temperature at the center of the plate thickness calculated using the difference method, which means that the steel plate surface temperature managed in normal controlled rolling is This is because, in the case of a thick steel plate, there is no correlation with the temperature of the central part of the plate thickness, and it does not serve as an index for accurately controlling the reduction amount in austenite recrystallization and non-recrystallization.
【００２６】さらに、板厚中央部の靭性を安定して得よ
うとするためには、圧延中の板厚中央部のオーステナイ
粒径の変化を推定し、鋼板毎の圧延終了後のオーステナ
イ平均粒径を適切な大きさに揃えることが有効であるこ
とに着目した。Further, in order to stably obtain the toughness in the central portion of the sheet thickness, the change in the austenite grain size in the central portion of the sheet thickness during rolling is estimated, and the average grain size of the austenite after the rolling is finished for each steel sheet. We paid attention to the fact that it is effective to arrange the diameters to an appropriate size.
【００２７】従って、圧延パラメータＤ（図１に示すフ
ローチャートにより計算される。また、圧延パラメータ
Ｄはオーステナイ平均粒径に対応する。）を厚肉材の板
厚中央部の靭性の関係を調査した結果、図２に示すよう
に、圧延パラメータＤと板厚中央部の靭性との間に相関
関係が成立しており、圧延パラメータＤを１０以下とす
ることによって、シャルピー破面遷移温度で−６０℃以
下の板厚中央部の靭性を安定して得られることがわかつ
た。Therefore, the rolling parameter D (calculated according to the flow chart shown in FIG. 1 and the rolling parameter D corresponds to the austenite average grain size) was investigated for the relationship of the toughness at the central portion of the thickness of the thick material. As a result, as shown in FIG. 2, a correlation is established between the rolling parameter D and the toughness of the central portion of the plate thickness, and by setting the rolling parameter D to 10 or less, the Charpy fracture surface transition temperature is −60. It was found that the toughness at the center of the plate thickness of ℃ or less can be stably obtained.
【００２８】即ち、厚肉鋼板の板厚中央部において、シ
ャルピー破面遷移温度が−６０℃以下の靭性を得るため
には、各パス毎の板厚中央部の温度（この温度は差分法
により計算される。）、圧下量、さらに、パス間時間を
も制御して、圧延パラメータが１０以下となるような圧
延条件とする必要がある。That is, in order to obtain toughness at a Charpy fracture surface transition temperature of -60 ° C. or lower in the central portion of the thick steel plate, the temperature of the central portion of the thickness of each pass (this temperature is determined by the difference method). It is necessary to control the amount of reduction and the time between passes so that the rolling parameters are 10 or less.
【００２９】また、仕上げ圧延後、５００℃以下の温度
域まで１〜２０℃／ｓｅｃの冷却速度で冷却するのは、
高強度を得るためであり、冷却停止温度が５００℃を越
える高い温度では、強度上昇の効果を得ることができ
ず、そして、冷却速度が１℃／ｓｅｃ未満では強度上昇
効果が少なく、１０℃／ｓｅｃを越える速い冷却速度で
は強度上昇が過大になり、靭性の劣化を招来する。よっ
て、冷却停止温度５００℃以下、冷却速度１〜１０℃／
ｓｅｃとする。After finishing rolling, cooling to a temperature range of 500 ° C. or lower at a cooling rate of 1 to 20 ° C./sec is
In order to obtain high strength, the effect of increasing the strength cannot be obtained at a high temperature where the cooling stop temperature exceeds 500 ° C., and the effect of increasing the strength is small when the cooling rate is less than 1 ° C./sec. If the cooling rate is faster than 1 / sec, the strength will increase excessively, resulting in deterioration of toughness. Therefore, the cooling stop temperature is 500 ° C or less, the cooling rate is 1 to 10 ° C /
Let be sec.
【００３０】[0030]
【実 施 例】本発明に係る板厚中央部の靭性の優れた
厚肉高靭性高張力鋼板の製造方法の実施例を説明する。[Examples] An example of a method for producing a thick, high-toughness, high-strength steel sheet having excellent toughness in the central portion of the sheet thickness according to the present invention will be described.
【００３１】[0031]
【実 施 例】表１に示す含有成分および成分割合の鋼を
通常の方法により、溶解、鋳造後に、表２に示す条件に
より所定の板厚の鋼板を製造した。そして、表３にこの
鋼板について、引張強さ、降伏強さ、板厚中央部のシャ
ルピー破面遷移おんどを調査した結果を示す。[Examples] Steel having the contained components and component ratios shown in Table 1 was melted and cast by a usual method, and then a steel plate having a predetermined plate thickness was manufactured under the conditions shown in Table 2. Then, Table 3 shows the results of examining the tensile strength, the yield strength, and the Charpy fracture surface transition pond at the center of the plate thickness of this steel plate.
【００３２】表２、表３からＮｏ.６は、加熱温度がＡ
ｃ3未満であり、８５０〜９００℃の温度における圧下
率で圧延を行うことができなかったので、圧延パラメー
タＤが１０を越え、板厚中央部のシャルピー破面遷移温
度（ｖＴｒｓ）が、−６０℃より高くなっている。Tables 2 and 3 to No. 6 show that the heating temperature is A
Since it was less than c 3 and could not be rolled at a reduction rate at a temperature of 850 to 900 ° C., the rolling parameter D exceeded 10, and the Charpy fracture surface transition temperature (vTrs) at the center of the plate thickness was − It is higher than 60 ° C.
【００３３】Ｎｏ.８は、８５０〜９００℃、Ａｒ3以
上、８００℃以下の温度における圧下率はそれぞれ確保
されているが、パス間時間が長くなつているため、圧延
パラメータＤが１０を越えており、Ｎｏ.５、Ｎｏ.９
は、８５０〜９００℃、Ａｒ3以上、８００℃以下の温
度における圧下率の何れかが確保できなかったので、圧
延パラメータが１０を越えており、両方共に板厚中央部
においてシャルピー破面遷移温度（ｖＴｒｓ）−６０℃
以下であり、低温用鋼板として適した性能を有していな
い。In No. 8, the rolling reductions at temperatures of 850 to 900 ° C., Ar 3 or higher and 800 ° C. or lower are secured, respectively, but since the time between passes is long, the rolling parameter D exceeds 10. No. 5, No. 9
Was not able to secure any of the rolling reductions at temperatures of 850 to 900 ° C., Ar 3 or higher and 800 ° C. or lower, the rolling parameters exceeded 10. Both of them had a Charpy fracture surface transition temperature at the center of the plate thickness. (VTrs) -60 ° C
It is below, and does not have the performance suitable as a low temperature steel plate.
【００３４】Ｎｏ.１０〜Ｎｏ.１２は、鋼の含有成分お
よび成分割合が本発明にかかる板厚中央部の靭性の優れ
た厚肉高靭性高張力鋼板の製造方法に使用されている鋼
の含有成分、成分割合から外れているので、加熱、圧延
条件が本発明に係る板厚中央部の靭性の優れた厚肉高靭
性高張力鋼板の製造方法の規定内であるが、何れも板厚
中央部の靭性が劣っている。No. 10 to No. 12 are steels used in the method for producing a thick and high toughness high strength steel sheet having excellent toughness in the central portion of the plate thickness according to the present invention, in terms of the contained components and component ratios of the steel. Since the contained components and component ratios deviate from each other, the heating and rolling conditions are within the provisions of the method for manufacturing a thick-walled high-toughness high-strength steel sheet having excellent toughness at the center portion of the plate thickness according to the present invention, but the plate thickness is The toughness of the central part is inferior.
【００３５】しかして、本発明に係る板厚中央部の靭性
の優れた厚肉高靭性高張力鋼板の製造方法では、Ｎｏ.
１〜Ｎｏ.４およびＮｏ.７は、その何れもが板厚中央部
において、シャルピー破面遷移温度（ｖＴｒｓ）は−６
０℃以下と優れた低温靭性を有している。Therefore, in the method for producing a thick-walled high-toughness high-strength steel sheet having excellent toughness in the center portion of the sheet thickness according to the present invention, No.
In all of No. 1 to No. 4 and No. 7, the Charpy fracture surface transition temperature (vTrs) is −6 at the central portion of the plate thickness.
It has excellent low temperature toughness of 0 ° C or less.
【００３６】[0036]
【表１】 [Table 1]
【００３７】[0037]
【表２】 [Table 2]
【００３８】[0038]
【表３】 [Table 3]
【００３９】[0039]
【発明の効果】以上説明したように、本発明に係る板厚
中央部の靭性の優れた厚肉高靭性高張力鋼板の製造方法
は上記の構成であるから、板厚中央部において優れた低
温靭性を有する板厚が８０ｍｍ以上の厚肉で高靭性高張
力鋼板を効率よく製造することができるという効果があ
る。As described above, the method for producing a thick and high-toughness high-strength steel sheet having excellent toughness in the central portion of the plate thickness according to the present invention has the above-mentioned configuration, and therefore, excellent low temperature in the central portion of the plate thickness. There is an effect that it is possible to efficiently manufacture a high-toughness high-strength steel sheet having a toughness and a thickness of 80 mm or more.
【図１】圧延パラメータＤを計算するためのフローチャ
ートを示す図である。FIG. 1 is a diagram showing a flowchart for calculating a rolling parameter D.
【図２】圧延パラメータＤと板厚中央部のシャルピー破
面遷移温度（ｖＴｒｓ）との関係を示す図である。FIG. 2 is a diagram showing a relationship between a rolling parameter D and a Charpy fracture surface transition temperature (vTrs) at the center of the plate thickness.
Claims (2)
１０〜０.５０ｗｔ％、 Ｍｎ ０.５〜２.０ｗｔ％、Ｐ ０．０１０ｗｔ％以
下、 Ｓ ０.００３ｗｔ％以下、Ａｌ ０.０１０〜０.１０
０ｗｔ％ Ｎｂ ０.００３〜０.０３０ｗｔ％、Ｔｉ ０.００５
〜０.０２０ｗｔ％、 Ｎ ０.００２０〜０.００６０ｗｔ％を含有し、残部Ｆ
ｅおよび不可避不純物からなる鋼を、Ａｃ3以上、１０
００℃以下の温度に加熱後、差分法を用いて計算される
板厚中央部の温度｛Ｔ(ｔ／２)｝が８５０〜９００℃、
圧下量２０％以上の粗圧延を行い、その後、板厚中央部
の温度｛Ｔ(ｔ／２)｝がＡｒ3以上、８００℃以下の温
度で、圧下量３０％以上の仕上げ圧延を行い、直ちに、
鋼板表面温度が５００℃以下の温度域まで１〜１０℃／
ｓｅｃの冷却速度により冷却を行い、圧延パラメーター
Ｄが１０以下になるように圧延条件を制御することを特
徴とする板厚中央部の靭性の優れた厚肉高靭性高張力鋼
板の製造方法。1. C 0.01-0.10 wt%, Si 0.
10-0.50 wt%, Mn 0.5-2.0 wt%, P 0.010 wt% or less, S 0.003 wt% or less, Al 0.010-0.10
0 wt% Nb 0.003 to 0.030 wt%, Ti 0.005
~ 0.020wt%, N 0.0020 ~ 0.0060wt%, balance F
steel containing e and unavoidable impurities, Ac 3 or more, 10
After heating to a temperature of 00 ° C. or lower, the temperature {T (t / 2)} at the center of the plate thickness calculated using the difference method is 850 to 900 ° C.,
Rough rolling with a reduction amount of 20% or more is performed, and then finish rolling with a reduction amount of 30% or more is performed at a temperature {T (t / 2)} of the plate thickness center portion of Ar 3 or more and 800 ° C. or less, right away,
Steel plate surface temperature is 1 to 10 ° C / up to a temperature range of 500 ° C or less
A method for producing a thick-walled high-toughness high-strength steel sheet having excellent toughness in the central portion of the plate thickness, characterized by cooling at a cooling rate of sec and controlling the rolling conditions such that the rolling parameter D is 10 or less.
１０〜０.５０ｗｔ％、 Ｍｎ ０.５〜２.０ｗｔ％、Ｐ ０．０１０ｗｔ％以
下、 Ｓ ０.００３ｗｔ％以下、Ａｌ ０.０１０〜０.１０
０ｗｔ％ Ｎｂ ０.００３〜０.０３０ｗｔ％、Ｔｉ ０.００５
〜０.０２０ｗｔ％、 Ｎ ０.００２０〜０.００６０ｗｔ％ を含有し、さらに、 Ｃｕ １.５ｗｔ％以下、Ｎｉ ３.０ｗｔ％以下、 Ｃａ ０.００５０ｗｔ％以下の中から選んだ１種また
は２種以上を含有し、残部Ｆｅおよび不可避不純物から
なる鋼を、Ａｃ3以上、１０００℃以下の温度に加熱
後、差分法を用いて計算される板厚中央部の温度｛Ｔ
(ｔ／２)｝が８５０〜９００℃、圧下量２０％以上の粗
圧延を行い、その後、板厚中央部の温度｛Ｔ(ｔ／２)｝
がＡｒ3以上、８００℃以下の温度で、圧下量３０％以
上の仕上げ圧延を行い、直ちに、鋼板表面温度が５００
℃以下の温度域まで１〜１０℃／ｓｅｃの冷却速度によ
り冷却を行い、圧延パラメーターＤが１０以下になるよ
うに圧延条件を制御することを特徴とする板厚中央部の
靭性の優れた厚肉高靭性高張力鋼板の製造方法。2. C 0.01 to 0.10 wt%, Si 0.
10-0.50 wt%, Mn 0.5-2.0 wt%, P 0.010 wt% or less, S 0.003 wt% or less, Al 0.010-0.10
0 wt% Nb 0.003 to 0.030 wt%, Ti 0.005
-0.020 wt%, N 0.0020-0.0060 wt%, and further, one or two selected from Cu 1.5 wt% or less, Ni 3.0 wt% or less, Ca 0.0005 wt% or less. After heating a steel containing at least seeds and consisting of balance Fe and unavoidable impurities to a temperature of Ac 3 or more and 1000 ° C. or less, the temperature of the central portion of the plate thickness calculated using the difference method {T
(t / 2)} is 850 to 900 ° C., a rolling amount of 20% or more is subjected to rough rolling, and then the temperature at the center of the thickness {T (t / 2)}
Is Ar 3 or more and 800 ° C. or less, and finish rolling is performed with a rolling reduction of 30% or more.
Cooling at a cooling rate of 1 to 10 ° C / sec to a temperature range of ℃ or less, and controlling the rolling conditions so that the rolling parameter D is 10 or less, a thickness with excellent toughness in the central portion of the plate thickness. Method for manufacturing high-strength, high-strength steel sheet.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16535292A JPH05331538A (en) | 1992-06-01 | 1992-06-01 | Manufacture of thick high toughness and high tensile strength steel plate excellent in toughness on central part of plate thickness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16535292A JPH05331538A (en) | 1992-06-01 | 1992-06-01 | Manufacture of thick high toughness and high tensile strength steel plate excellent in toughness on central part of plate thickness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05331538A true JPH05331538A (en) | 1993-12-14 |
Family
ID=15810733
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP16535292A Pending JPH05331538A (en) | 1992-06-01 | 1992-06-01 | Manufacture of thick high toughness and high tensile strength steel plate excellent in toughness on central part of plate thickness |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05331538A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5900076A (en) * | 1994-09-20 | 1999-05-04 | Kawasaki Steel Corporation | Bainitic steel materials having a less scattering of properties and method of producing the same |
| JP2003129134A (en) * | 2001-10-18 | 2003-05-08 | Nippon Steel Corp | Method for manufacturing high-strength steel sheet superior in low-temperature toughness |
| US6753039B2 (en) | 2001-08-03 | 2004-06-22 | Elisha Holding Llc | Electrolytic and electroless process for treating metallic surfaces and products formed thereby |
-
1992
- 1992-06-01 JP JP16535292A patent/JPH05331538A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5900076A (en) * | 1994-09-20 | 1999-05-04 | Kawasaki Steel Corporation | Bainitic steel materials having a less scattering of properties and method of producing the same |
| US6753039B2 (en) | 2001-08-03 | 2004-06-22 | Elisha Holding Llc | Electrolytic and electroless process for treating metallic surfaces and products formed thereby |
| JP2003129134A (en) * | 2001-10-18 | 2003-05-08 | Nippon Steel Corp | Method for manufacturing high-strength steel sheet superior in low-temperature toughness |
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