JPH1121625A - Production of thick steel plate excellent in strength and toughness - Google Patents
Production of thick steel plate excellent in strength and toughnessInfo
- Publication number
- JPH1121625A JPH1121625A JP17682197A JP17682197A JPH1121625A JP H1121625 A JPH1121625 A JP H1121625A JP 17682197 A JP17682197 A JP 17682197A JP 17682197 A JP17682197 A JP 17682197A JP H1121625 A JPH1121625 A JP H1121625A
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- Prior art keywords
- rolling
- transformation point
- cooling
- toughness
- steel
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Abstract
Description
【0001】[0001]
【発明の属する技術分野】この発明は、厚鋼板の製造に
関するものであるが、建築、海洋構造物、パイプ、造
船、貯槽、土木、建設機械などの分野で利用される鋼
帯、形鋼又は棒鋼などの非調質鋼材の製造方法にも適用
できる。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the manufacture of steel plates, and more particularly, to steel strips, shaped steels, and the like used in the fields of construction, marine structures, pipes, shipbuilding, storage tanks, civil engineering, construction machinery, and the like. The present invention is also applicable to a method for manufacturing a non-heat treated steel material such as a bar.
【0002】[0002]
【従来の技術】厚鋼板において強度、靱性、溶接性を確
保する方法として、TMCP(ThermoMechanical Contro
l Process) による製造方法が知られている。例えば、
特開平3-223419号公報には、熱間圧延で(Ar3点+150
℃) 以上の再結晶域で30%以上の圧下を施した後、(Ar3
+150 ℃) 〜Ar3 点で50%以上の圧下を加えて変形帯を
導入することにより組織の微細化を図る方法が開示され
ている。また、特開昭64-73019号公報には、(Ae3−200
℃) 〜(Ae3−250 ℃) 以下の温度域で2相域圧延を施す
ことにより、加工中にフェライトを生じさせ、微細なフ
ェライト組織とする手法が開示されている。2. Description of the Related Art As a method for securing strength, toughness, and weldability of a thick steel plate, a thermal mechanical control (TMCP) method is used.
l Process) is known. For example,
JP-A-3-223419 discloses that hot rolling (Ar 3 points + 150
After applying the pressure of 30% or more at ° C.) or more recrystallization region, (Ar 3
A method of miniaturizing the structure by introducing a deformation zone by applying a reduction of 50% or more at three points of + 150 ° C. to Ar is disclosed. Further, in JP-A-64-73019, (Ae 3 -200
By subjecting the 2-phase region rolling at ℃) ~ (Ae 3 -250 ℃ ) below a temperature range, cause ferrite, method of a fine ferrite structure is disclosed during processing.
【0003】しかしながら、これらの従来技術において
は、極厚鋼板において、軽圧下となった際に変形帯が十
分に導入されずフェライトの核が減少したり、薄肉鋼板
においては集合組織の影響による音響異方性や、残留応
力、歪みの影響も大きいなどの問題があった。さらに、
未再結晶域において圧下を加えるために圧延中に長時間
の温度調節をするため、圧延能率性が大きく低下すると
ともに、残留応力や歪の発生により鋼板の変形挙動を十
分に制御できない問題もある。However, in these prior arts, in a very thick steel plate, when light pressure is applied, the deformation zone is not sufficiently introduced, so that the ferrite nucleus is reduced. There were problems such as the effects of anisotropy, residual stress, and strain being large. further,
Long-term temperature control during rolling to apply rolling in the non-recrystallized region significantly reduces rolling efficiency, and there is also a problem that the deformation behavior of the steel sheet cannot be sufficiently controlled due to the occurrence of residual stress and strain. .
【0004】また、鉄と鋼第77年 (1991年) 第1号 P.1
71には、V,Nを添加した高強度のアズロールド鋼材の
特性が示されているが、極厚鋼板のような軽圧下率圧延
で仕上げ温度が 950℃以上の圧延条件では良好な強度、
靱性が得られなかった。[0004] Also, Iron and Steel No. 77 (1991) No. 1 P.1
The properties of high-strength as-rolled steel material to which V and N are added are shown in No. 71.
No toughness was obtained.
【0005】[0005]
【発明が解決しようとする課題】この発明では、残留応
力・歪みを発生させることなく高強度・高靱性を確保で
き、強度・靱性に優れる厚鋼板の製造方法を提案するこ
とを目的とする。SUMMARY OF THE INVENTION It is an object of the present invention to propose a method for manufacturing a thick steel plate which can ensure high strength and high toughness without generating residual stress and strain, and is excellent in strength and toughness.
【0006】[0006]
【課題を解決するための手段】発明者らは、上記目的を
達成するため、種々の実験・研究を行った結果、適正な
Ti, V,N量を含有する鋼において、TiN, VN あるいは
TiN とVNの複合析出物を核としたフェライト変態が強磁
場中で変態促進されることを見出し、微細なフェライト
−パーライト組織の形成により強度・靱性を向上させ得
ることが明らかになった。また、REM 、Ca、Oを含有す
る鋼において、REM 及びCaのオキサイド系介在物を核と
したフェライト変態の促進が強磁場中で生じることを見
出し、Ti, V,N量を含有する鋼と同じく微細なフェラ
イト−パーライト組織の形成により強度・靱性を向上さ
せ得ることが明らかになった。更に、B、Nを含有する
鋼においてはBNを核としたフェライト変態の促進が強磁
場中で生じることを見出した。Means for Solving the Problems The inventors have conducted various experiments and studies in order to achieve the above object, and have found that
For steels containing Ti, V, N contents, TiN, VN or
It was found that the transformation of ferrite using TiN and VN composite precipitates as nuclei was promoted in a strong magnetic field, and it was clarified that the formation of a fine ferrite-pearlite structure could improve the strength and toughness. Further, in steels containing REM, Ca, and O, it was found that the promotion of ferrite transformation centered on oxide-based inclusions of REM and Ca occurred in a strong magnetic field. Similarly, it was revealed that the formation of a fine ferrite-pearlite structure can improve strength and toughness. Furthermore, it has been found that in a steel containing B and N, promotion of ferrite transformation with BN as a nucleus occurs in a strong magnetic field.
【0007】この発明はこれらの知見に基づきなされた
ものであり、その要旨構成は次のとおりである。 〔第1発明〕 C:0.05〜0.18wt%、Si:0.05〜0.6 wt%、Mn:0.60〜
2.00wt%、Al:0.005 〜0.050 wt%、P:0.020 wt%以
下、S:0.015 wt%以下及びN:0.0050〜0.0150wt%を
含み、かつV:0.04〜0.15wt%及びTi:0.01〜0.15wt%
の1種又は2種を含有し、残部はFe及び不可避的不純物
からなる鋼をAr3 変態点以上に加熱・均熱した後、熱間
圧延を施し、その際に式(1) にて各成分の含有量より定
義されるAr3 変態点以上の温度で圧延を終了し、圧延終
了からAr3 変態点−100 ℃の温度までを2 T 以上の磁場
中で冷却し、その後室温まで空冷あるいは加速冷却する
ことを特徴とする強度・靱性に優れた厚鋼板の製造方
法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1) 〔第2発明〕 C:0.05〜0.18wt%、Si:0.05〜0.6 wt%、Mn:0.60〜
2.00wt%、Al:0.005 〜0.050 wt%、P:0.020 wt%以
下、S:0.015 wt%以下及びN:0.0050〜0.0150wt%を
含み、かつ、V:0.04〜0.15wt%及びTi:0.01〜0.15wt
%の1種又は2種を含有し、更に、選択成分としてCu:
0.05〜2.0 wt%、Ni:0.05〜0.60wt%、Nb:0.003 〜0.
020 wt%、Cr:0.05〜0.50wt%、Mo:0.02〜0.10wt%、
の1種又は2種以上からなる群、B:0.0002〜0.0020wt
%よりなる群、REM :0.0010〜0.0200wt%、Ca:0.0010
〜0.0100wt%の1種又は2種とO:0.0040〜0.0150wt%
とからなる群の少なくとも1群を含有し、残部はFe及び
不可避的不純物からなる鋼をAr3 変態点以上に加熱・均
熱した後、熱間圧延を施し、その際に式(1) にて各成分
の含有量より定義されるAr3 変態点以上の温度で圧延を
終了し、圧延終了からAr3 変態点−100 ℃の温度までを
2 T 以上の磁場中で冷却し、その後室温まで空冷あるい
は加速冷却することを特徴とする強度・靱性に優れた厚
鋼板の製造方法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1) 〔第3発明〕 C:0.05〜0.18wt%、Si:0.05〜0.6 wt%、Mn:0.60〜
2.00wt%、Al:0.005 〜0.050 wt%、P:0.020 wt%以
下、S:0.015 wt%以下及びO:0.0040〜0.0150wt%を
含み、かつ、Ti:0.01〜0.15wt%REM :0.0010〜0.0200
wt%、Ca:0.0010〜0.0100wt%の1種又は2種以上を含
有し、残部はFe及び不可避的不純物からなる鋼をAr3 変
態点以上に加熱・均熱した後、熱間圧延を施し、その際
に式(1) にて各成分の含有量より定義されるAr3 変態点
以上の温度で圧延を終了し、圧延終了からAr3 変態点−
100 ℃の温度までを2 T 以上の磁場中で冷却し、その後
室温まで空冷あるいは加速冷却することを特徴とする強
度・靱性に優れた厚鋼板の製造方法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1) 〔第4発明〕 C:0.05〜0.18wt%、Si:0.05〜0.6 wt%、Mn:0.60〜
2.00wt%、Al:0.005 〜0.050 wt%、P:0.020 wt%以
下、S:0.015 wt%以下及びO:0.0040〜0.0150wt%を
含み、かつ、Ti:0.01〜0.15wt%REM :0.0010〜0.0200
wt%、Ca:0.0010〜0.0100wt%の1種又は2種以上を含
有し、更に、選択成分としてCu:0.05〜2.0 wt%、Ni:
0.05〜0.60wt%、Nb:0.003 〜0.020 wt%、Cr:0.05〜
0.50wt%、Mo:0.02〜0.10wt%、の1種又は2種以上か
らなる群、B:0.0002〜0.0020wt%、V:0.04〜0.15wt
%の1種又は2種とN:0.0050〜0.0150wt%とからなる
群、の少なくとも1群を含有し、残部はFe及び不可避的
不純物からなる鋼をAr3 変態点以上に加熱・均熱した
後、熱間圧延を施し、その際に式(1) にて各成分の含有
量より定義されるAr3 変態点以上の温度で圧延を終了
し、圧延終了からAr3 変態点−100 ℃の温度までを2 T
以上の磁場中で冷却し、その後室温まで空冷あるいは加
速冷却することを特徴とする強度・靱性に優れた厚鋼板
の製造方法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1)[0007] The present invention has been made based on these findings, and the gist configuration thereof is as follows. [First invention] C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 to
2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less, N: 0.0050 to 0.0150 wt%, V: 0.04 to 0.15 wt% and Ti: 0.01 to 0.15 wt% wt%
After heating and equalizing the steel consisting of Fe and unavoidable impurities to the Ar 3 transformation point or higher, the remainder is subjected to hot rolling. Rolling is completed at a temperature equal to or higher than the Ar 3 transformation point defined by the content of the component, and from the end of the rolling, the temperature up to the Ar 3 transformation point −100 ° C. is cooled in a magnetic field of 2 T or more, and then air-cooled to room temperature or A method for manufacturing a thick steel plate having excellent strength and toughness, characterized by accelerated cooling. Ar 3 (° C.) = 910−230C + 25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb (1) [Second invention] C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 ~
2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less, and N: 0.0050 to 0.0150 wt%, and V: 0.04 to 0.15 wt% and Ti: 0.01 to 0.01 wt%. 0.15wt
% Of one or two kinds, and further contains Cu:
0.05-2.0 wt%, Ni: 0.05-0.60 wt%, Nb: 0.003--0.
020 wt%, Cr: 0.05-0.50 wt%, Mo: 0.02-0.10 wt%,
A group consisting of one or more of the following, B: 0.0002 to 0.0020 wt
%, REM: 0.0010 to 0.0200 wt%, Ca: 0.0010
One or two kinds of O-0.0100wt% and O: 0.0040-0.0150wt%
And at least one of the group consisting of Fe and a steel consisting of unavoidable impurities is heated and soaked at a temperature equal to or higher than the Ar 3 transformation point, and then hot-rolled. The rolling is completed at a temperature equal to or higher than the Ar 3 transformation point defined by the content of each component, and from the end of the rolling to the temperature of the Ar 3 transformation point −100 ° C.
A method of manufacturing a steel plate having excellent strength and toughness, characterized by cooling in a magnetic field of 2 T or more, and then cooling by air or accelerated cooling to room temperature. Ar 3 (° C.) = 910−230C + 25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb (1) [Third invention] C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 ~
2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less, O: 0.0040 to 0.0150 wt%, and Ti: 0.01 to 0.15 wt% REM: 0.0010 to 0.0200
wt%, Ca: 0.0010-0.0100wt%, containing one or more kinds, and the balance consisting of Fe and unavoidable impurities is heated and soaked to the Ar 3 transformation point or higher, and then hot-rolled. At that time, rolling is completed at a temperature not lower than the Ar 3 transformation point defined by the content of each component in Equation (1), and from the end of rolling, the Ar 3 transformation point −
A method for manufacturing thick steel sheets with excellent strength and toughness, characterized by cooling to a temperature of 100 ° C in a magnetic field of 2 T or more, and then cooling to room temperature by air or accelerated cooling. Ar 3 (° C.) = 910−230C + 25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb (1) [4th invention] C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 ~
2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less, O: 0.0040 to 0.0150 wt%, and Ti: 0.01 to 0.15 wt% REM: 0.0010 to 0.0200
wt%, Ca: one or more of 0.0010 to 0.0100 wt%, and Cu: 0.05 to 2.0 wt%, Ni:
0.05 to 0.60 wt%, Nb: 0.003 to 0.020 wt%, Cr: 0.05 to
A group consisting of one or more of 0.50 wt%, Mo: 0.02 to 0.10 wt%, B: 0.0002 to 0.0020 wt%, V: 0.04 to 0.15 wt
% Or more, and at least one group of N: 0.0050 to 0.0150 wt%, and the balance was heated and soaked at a temperature above the Ar 3 transformation point of steel consisting of Fe and unavoidable impurities. Thereafter, hot rolling is performed, and at that time, the rolling is completed at a temperature equal to or higher than the Ar 3 transformation point defined by the content of each component in the formula (1), and the Ar 3 transformation point −100 ° C. 2 T up to temperature
A method for producing a thick steel sheet having excellent strength and toughness, wherein the steel sheet is cooled in the above-described magnetic field, and then cooled to room temperature by air or accelerated cooling. Ar 3 (° C) = 910-230C + 25Si-74Mn-56Ni-16Cr-9Mo-5Cu-1620Nb ... (1)
【0008】[0008]
【発明の実施の形態】以下にこの発明の限定理由を、ま
ず化学組成について説明する。Cは強度を確保するため
に0.05wt%以上を必要とするが、0.18wt%を超えると母
材靱性及び溶接性が低下するので、0.05〜0.18wt%に限
定した。BEST MODE FOR CARRYING OUT THE INVENTION The reasons for the limitation of the present invention will first be described in terms of chemical composition. C requires 0.05% by weight or more to secure strength, but if it exceeds 0.18% by weight, the base material toughness and weldability are reduced. Therefore, C is limited to 0.05 to 0.18% by weight.
【0009】Siは鋼の脱酸と強度上昇に有効であるが、
0.05wt%に満たないとその効果がなく、0.60wt%を超え
ての添加は HAZ靱性を著しく劣化させるので、0.05〜0.
60wt%に限定した。Although Si is effective in deoxidizing steel and increasing strength,
If the content is less than 0.05 wt%, the effect is not obtained, and if added over 0.60 wt%, the HAZ toughness is significantly deteriorated.
Limited to 60 wt%.
【0010】Mnは高強度化に有効な成分であり、強度確
保の観点から下限を0.60wt%とした。しかし、Mn量が2.
00wt%を超えると、圧延空冷組織がフェライト+パーラ
イトからフェライト+ベイナイトになり、母材靱性が低
下するためにその上限を2.00wt%にした。Mn is a component effective for increasing the strength, and the lower limit is set to 0.60 wt% from the viewpoint of securing the strength. However, the amount of Mn is 2.
When the content exceeds 00 wt%, the rolled air-cooled structure changes from ferrite + pearlite to ferrite + bainite, and the base material toughness is reduced. Therefore, the upper limit is set to 2.00 wt%.
【0011】Alは脱酸のために 0.005wt%以上必要であ
るが、0.050 wt%を超えて添加しても脱酸効果は飽和す
るので、上限を 0.050wt%とした。Pは靱性を劣化させ
るので、0.020 wt%以下に制限した。Sは鋼中で主に M
nSとして存在し、圧延により MnSが伸長し、延性及び靱
性の異方性を生じるため 0.015wt%以下に限定した。た
だし、MnS にもフェライト変態核としての効果が期待で
きるため、0.004 〜0.010 wt%とするのが望ましい。[0011] Al is required to be at least 0.005 wt% for deoxidation. However, the addition of more than 0.050 wt% saturates the deoxidizing effect, so the upper limit was made 0.050 wt%. Since P deteriorates toughness, it is limited to 0.020 wt% or less. S is mainly M in steel
MnS exists as nS, and MnS elongates by rolling, causing anisotropy in ductility and toughness. Therefore, the content was limited to 0.015 wt% or less. However, since MnS can also be expected to have an effect as a ferrite transformation nucleus, the content is preferably 0.004 to 0.010 wt%.
【0012】Vは圧延冷却中にVNとしてオーステナイト
中に析出し、それを核としてフェライトが析出すること
から結晶粒を微細化させ、靱性向上に大きく寄与する。
また、フェライト変態後にフェライト中へVNが析出し、
冷却時に強水冷を行わずに母材強度も高めることができ
るため、板厚内での特性の均一性、残留応力・歪み軽減
にも有効である。これらの効果を有効に発揮させるに
は、0.04wt%以上の添加が必要であるが、0.15wt%を超
えての添加は母材靱性や溶接性を大きく損なうので、0.
04〜0.15wt%に限定した。V precipitates as a VN in austenite during rolling and cooling, and ferrite precipitates using it as a nucleus, thereby making crystal grains finer and greatly contributing to improvement in toughness.
Also, after ferrite transformation, VN precipitates in the ferrite,
Since the base metal strength can be increased without performing strong water cooling at the time of cooling, it is also effective for uniformity of properties within the sheet thickness and for reduction of residual stress and distortion. To exert these effects effectively, it is necessary to add 0.04% by weight or more.However, if it exceeds 0.15% by weight, the toughness and weldability of the base material are greatly impaired.
Limited to 04-0.15 wt%.
【0013】Tiは主に TiNとして存在し、素材加熱時に
γの粒成長を抑制する作用並びにγ中への残留及び析出
によりフェライト生成核あるいはVNのγ中への析出を促
進させる作用を持つことから、結晶粒の微細化に有効な
成分である。また、Tiは酸化物として存在することによ
りフェライト生成能を有する。これらの効果を発揮させ
るには0.01wt%以上の添加が必要であり、0.15wt%を超
えての添加は鋼の清浄性や靱性を低下させるので0.01〜
0.15wt%に限定した。Ti is present mainly as TiN, and has an action of suppressing the grain growth of γ during heating of the material and an action of accelerating the precipitation of ferrite-forming nuclei or VN into γ by remaining and precipitating in γ. Therefore, it is an effective component for refining crystal grains. Further, Ti has a ferrite forming ability by being present as an oxide. In order to exert these effects, it is necessary to add 0.01 wt% or more, and if it exceeds 0.15 wt%, the cleanliness and toughness of the steel will be reduced.
Limited to 0.15 wt%.
【0014】NはTiN やVNあるいはBNを形成し、素材加
熱時のγの粒成長の抑制とそれらを核としてフェライト
が析出することから結晶粒を微細化させ、靱性向上に大
きく寄与する。また、フェライト変態後にフェライト中
へVNが析出し、冷却時に強水冷を行わずに母材強度も高
めることができるため、板厚内での特性の均一生、残留
応力・歪み低減にも有効である。これらの効果を有効に
発揮させるためには0.005 wt%以上の添加が必要である
が、0.015 wt%を超えての添加は母材靱性や溶接性を大
きく損なうので0.005 〜0.015 wt%に限定した。N forms TiN, VN or BN, suppresses the grain growth of γ during the heating of the material and precipitates ferrite using these as nuclei, thereby making the crystal grains finer and greatly contributing to the improvement of toughness. In addition, VN precipitates in the ferrite after ferrite transformation, and the strength of the base material can be increased without performing strong water cooling during cooling, so it is effective for uniform production of properties within the sheet thickness and reduction of residual stress and strain. is there. In order to exert these effects effectively, it is necessary to add 0.005 wt% or more. However, if it exceeds 0.015 wt%, it greatly impairs the base metal toughness and weldability, so it was limited to 0.005 to 0.015 wt%. .
【0015】第2発明、第4発明においては、Cu, Ni,
Nb, Cr, Moの1種又は2種以上を添加することができ
る。これらの成分はいずれも焼入れ性向上に有効な成分
であり、TiN, VN との細粒化効果が最適になるとともに
VNの析出強化も有効に作用する。すなわち、Ar3 変態点
を下げることにより、フェライト粒がより微細に生成す
ると共にVNの析出強化が大きくなるが、Ar3 変態点を下
げすぎるとベイナイト変態が主体となり、フェライト生
成の細粒化が不十分になるため、強度は組織強化により
上昇するが母材靱性が大きく低下する。Ar3 変態点の低
下を介して強度・靱性を向上するためにはCu, Ni, Nb,
Cr, Moはそれぞれ0.05wt%, 0.05wt%, 0.003 wt%, 0.
05wt%, 0.02wt%以上が必要である。Cuによる熱間加工
性の低下を補償するためにNiはCuとほぼ等量の添加を必
要とするが、0.6 wt%を超えての添加は製造コストが高
くなりすぎるため、好ましくはCu, Niの上限は0.60wt%
とした。もっとも、Cuは析出強化成分であり、強度調整
のために2.0 wt%までは添加しても良いが、2.0 wt%を
超えると溶接熱影響部や圧延時の耐割れ性が低下するた
め上限は2.0 wt%とした。また、Nb, Cr, Moはそれぞれ
0.020wt%, 0.50wt%, 0.10wt%を超えると溶接性や靱
性を損なうので、これを上限とした。In the second invention and the fourth invention, Cu, Ni,
One or more of Nb, Cr and Mo can be added. Each of these components is an effective component for improving hardenability, and the effect of grain refinement with TiN and VN is optimized and
VN precipitation strengthening also works effectively. That is, by lowering the Ar 3 transformation point, ferrite grains are more finely formed and precipitation strengthening of VN is increased.However, if the Ar 3 transformation point is lowered too much, bainite transformation is mainly performed, and finer ferrite formation is reduced. Since the strength becomes insufficient, the strength increases due to the strengthening of the structure, but the toughness of the base material greatly decreases. In order to improve strength and toughness through lowering of the Ar 3 transformation point, Cu, Ni, Nb,
Cr and Mo are 0.05wt%, 0.05wt%, 0.003wt%, 0.
More than 05wt%, 0.02wt% is required. In order to compensate for the decrease in hot workability due to Cu, Ni needs to be added in an approximately equivalent amount to Cu. However, if Ni exceeds 0.6 wt%, the production cost becomes too high. The upper limit is 0.60wt%
And However, Cu is a precipitation strengthening component, and may be added up to 2.0 wt% for strength adjustment. However, if it exceeds 2.0 wt%, the weld heat affected zone and the cracking resistance during rolling decrease, so the upper limit is set. 2.0 wt%. Nb, Cr and Mo are each
If it exceeds 0.020 wt%, 0.50 wt%, or 0.10 wt%, the weldability and toughness are impaired.
【0016】第2発明、第4発明においては、Bを添加
することができる。BはTi及びVと同様、BNとしてフェ
ライト生成核となるが、粒界に偏析して粗大な粒界フェ
ライトの生成を抑制し、圧延後のフェライト粒を細かく
する作用をもつ。Bの0.0002wt%以上の添加によりその
効果が現れるが、0.0020wt%を超えての添加は靱性を低
下させるので、0.0002〜0.0020wt%に限定した。In the second and fourth inventions, B can be added. B, like Ti and V, becomes a nucleus for ferrite as BN, but segregates at the grain boundary to suppress the formation of coarse grain boundary ferrite, and has the effect of making the ferrite grains after rolling fine. The effect is exhibited by the addition of B in an amount of 0.0002 wt% or more, but the addition of more than 0.0020 wt% lowers the toughness, so the content was limited to 0.0002 to 0.0020 wt%.
【0017】第2発明、第3発明又は第4発明において
は、 REM, Caの1種又は2種を添加することができる。
REM, Ca は高温においても安定な酸化物として微細分散
し、素材加熱時のγ粒の粒成長を抑制するとともに、圧
延後のフェライト粒径を細かくする効果がある。また、
HAZ 靱性の向上にも有効であり、これら効果を期待する
際には、それぞれ0.0010wt%以上が必要であるが、それ
ぞれ0.0200wt%を超えての添加は鋼の清浄性及び母材靱
性を低下させるので、REM, Ca は0.0010〜0.0200wt%の
範囲とした。In the second, third or fourth invention, one or two of REM and Ca can be added.
REM and Ca are finely dispersed as oxides that are stable even at high temperatures, and have the effect of suppressing the growth of γ grains during material heating and of reducing the ferrite grain size after rolling. Also,
It is also effective in improving HAZ toughness, and when these effects are expected, 0.0010 wt% or more of each is required. However, addition of more than 0.0200 wt% decreases the cleanliness and base metal toughness of steel. Therefore, REM, Ca was set in the range of 0.0010 to 0.0200 wt%.
【0018】第2発明においては所定量のOを含有させ
ることができ、第3発明、第4発明においては、Oを必
須とする。Oは、上記REM 、Ca及びTiの酸化物の生成量
を確保するのに必要不可欠であり、O:0.0040〜0.0150
%の範囲に限定したのは、0.0040wt%未満では酸化物の
生成量が十分でなく、0.0150wt%を超えると鋼の清浄性
及び母材靱性を定価させることになるためである。In the second invention, a predetermined amount of O can be contained, and in the third invention and the fourth invention, O is essential. O is indispensable for securing the production amount of the oxides of REM, Ca and Ti, and O: 0.0040 to 0.0150
The reason for limiting to the range of% is that if the amount is less than 0.0040 wt%, the amount of oxides generated is not sufficient, and if the amount exceeds 0.0150 wt%, the cleanliness and base metal toughness of the steel are determined.
【0019】以上の理由により、この発明の化学組成の
限定範囲のなかで重要なのはフェライト生成の核となる
析出物及び介在物を確保することであり、Ti、V及びB
のような窒化物系介在物及び析出物を利用する場合には
Nは必須成分であり、REM 、Ca及びTiのような酸化物系
介在物及び析出物を利用する場合にはOが必須成分とな
る。また、これらの効果を同時に利用することも可能で
ある。For the above reasons, it is important in the limited range of the chemical composition of the present invention to secure the precipitates and inclusions serving as nuclei for ferrite formation.
N is an essential component when nitride-based inclusions and precipitates such as are used, and O is an essential component when oxide-based inclusions and precipitates such as REM, Ca and Ti are used. Becomes It is also possible to use these effects at the same time.
【0020】次に製造方法の限定理由について述べる。
素材加熱温度は素材の組織を均一なオーステナイト組織
にするため、Ar3 変態点以上必要であり、Ar3 変態点未
満ではフェライト変態後に均一な組織が得られないため
に、Ar3 変態点以上と限定した。圧延条件についてはこ
の発明の場合、高温にて圧延仕上げを行うと後述の磁場
中にて析出物を核とした粒内フェライト変態が促進さ
れ、低温にて圧延仕上げを行うと析出物からの変態に加
えて加工による変態帯からのフェライト変態が促進され
る。すなわち、いずれにせよ磁場中にて変態を起こさせ
ることが重要なポイントである。よって、Ar3 点以上で
の圧延終了温度から変態がほぼ完了する Ar3−100 ℃に
おいて磁場を付加することがこの発明の特徴である。こ
のとき付加する磁場は2T以上が変態促進には必要であ
り、それ未満では効果がない。Next, the reasons for limiting the manufacturing method will be described.
Since the material heating temperature to a uniform austenite structure materials of tissue requires more Ar 3 transformation point, Ar 3 to uniform structure after ferrite transformation is less than the transformation point is not obtained, Ar 3 transformation point or more and Limited. Regarding the rolling conditions, in the case of the present invention, when rolling is performed at a high temperature, intragranular ferrite transformation with precipitates as nuclei is promoted in a magnetic field described below, and when performing rolling at a low temperature, transformation from the precipitate is performed. In addition, ferrite transformation from the transformation zone due to processing is promoted. That is, in any case, it is an important point to cause transformation in a magnetic field. Therefore, it is a feature of the present invention that a magnetic field is applied at Ar 3 −100 ° C. where the transformation is almost completed from the rolling end temperature at the Ar 3 point or higher. At this time, a magnetic field of 2 T or more is necessary for promoting the transformation, and a magnetic field of less than 2 T has no effect.
【0021】[0021]
【実施例】表1に示した組成の溶製材を板厚50mmから15
mmに圧延し、得られた各鋼板の板厚中央部のミクロ組織
観察から、フェライト粒径を円相当径にて評価し、磁場
付加の効果を調べた。これらの結果を表2に示す。この
結果から、この発明による製造方法ではフェライト粒径
が小さくなり、変態時に高磁場を付加することで、強度
・靱性に優れた鋼板の製造が可能となった。EXAMPLE An ingot having the composition shown in Table 1 was used to reduce the thickness from 50 mm to 15 mm.
From the microstructure observation at the center of the thickness of each of the obtained steel sheets, the ferrite grain size was evaluated in terms of a circle-equivalent diameter, and the effect of applying a magnetic field was examined. Table 2 shows the results. From these results, the ferrite grain size was reduced in the manufacturing method according to the present invention, and by applying a high magnetic field during transformation, it was possible to manufacture a steel sheet having excellent strength and toughness.
【0022】[0022]
【表1】 [Table 1]
【0023】[0023]
【表2】 [Table 2]
【0024】[0024]
【発明の効果】この発明によれば、建築構造用柱材・梁
材としてこれまで製造が困難であった強度・靱性に優れ
た高強度厚鋼板の製造が可能となり、産業上の有益な効
果を奏する。According to the present invention, it is possible to manufacture a high-strength steel plate having excellent strength and toughness which has been difficult to manufacture as a pillar or beam for a building structure. To play.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 FI C22C 38/58 C22C 38/58 (72)発明者 川端 文丸 岡山県倉敷市水島川崎通1丁目(番地な し) 川崎製鉄株式会社水島製鉄所 (72)発明者 天野 虔一 岡山県倉敷市水島川崎通1丁目(番地な し) 川崎製鉄株式会社水島製鉄所 (72)発明者 下斗米 道夫 千葉県千葉市中央区川崎町1番地 川崎製 鉄株式会社技術研究所内──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 6 Identification code FI C22C 38/58 C22C 38/58 (72) Inventor Fumimaru Kawabata 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Pref. Mizushima Works, Ltd. (72) Inventor Kenichi Amano 1-chome, Mizushima Kawasaki-dori, Kurashiki-shi, Okayama Pref. Kawasaki Steel Works, Ltd. Mizushima Steel Works, Ltd. Address Kawasaki Steel Corp.
Claims (4)
からなる鋼をAr3 変態点以上に加熱・均熱した後、熱間
圧延を施し、その際に式(1) にて各成分の含有量より定
義されるAr3 変態点以上の温度で圧延を終了し、圧延終
了からAr3 変態点−100 ℃の温度までを2 T 以上の磁場
中で冷却し、その後室温まで空冷あるいは加速冷却する
ことを特徴とする強度・靱性に優れた厚鋼板の製造方
法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1)1. C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 to 2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less and N: comprises 0.0050~0.0150Wt%, and V: 0.04~0.15wt% and Ti: containing 0.01~0.15Wt% of one or, the balance being Fe and unavoidable impurities steel Ar 3 After heating and soaking above the transformation point, hot rolling is performed.At that time, rolling is completed at a temperature not less than the Ar 3 transformation point defined by the content of each component in equation (1), and rolling is completed A method for producing a thick steel plate having excellent strength and toughness, comprising cooling from a temperature of up to an Ar 3 transformation point of −100 ° C. in a magnetic field of 2 T or more, followed by air cooling or accelerated cooling to room temperature. Ar 3 (° C) = 910-230C + 25Si-74Mn-56Ni-16Cr-9Mo-5Cu-1620Nb ... (1)
不可避的不純物からなる鋼をAr3 変態点以上に加熱・均
熱した後、熱間圧延を施し、その際に式(1) にて各成分
の含有量より定義されるAr3 変態点以上の温度で圧延を
終了し、圧延終了からAr3 変態点−100 ℃の温度までを
2 T 以上の磁場中で冷却し、その後室温まで空冷あるい
は加速冷却することを特徴とする強度・靱性に優れた厚
鋼板の製造方法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1)2. C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 to 2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less And N: 0.0050 to 0.0150% by weight, and V: 0.04 to 0.15% by weight and Ti: 0.01 to 0.15% by weight, and Cu: 0.05 to 2.0% by weight as a selective component. , Ni: 0.05 to 0.60 wt%, Nb: 0.003 to 0.020 wt%, Cr: 0.05 to 0.50 wt%, Mo: 0.02 to 0.10 wt%, a group consisting of one or more of: B: 0.0002 to 0.0020 wt %, REM: 0.0010 to 0.0200 wt%, Ca: 0.0010 to 0.0100 wt%, and at least one of the group consisting of O: 0.0040 to 0.0150 wt%, with the balance being Fe and After heating and soaking the steel consisting of unavoidable impurities to the Ar 3 transformation point or higher, hot rolling is performed, and at that time, the Ar 3 transformation point or more defined by the content of each component in Equation (1) is used. Finish rolling at the temperature and from the end of rolling Ar 3 transformation point up to 100 ° C
A method of manufacturing a steel plate having excellent strength and toughness, characterized by cooling in a magnetic field of 2 T or more, and then cooling by air or accelerated cooling to room temperature. Ar 3 (° C) = 910-230C + 25Si-74Mn-56Ni-16Cr-9Mo-5Cu-1620Nb ... (1)
純物からなる鋼をAr3 変態点以上に加熱・均熱した後、
熱間圧延を施し、その際に式(1) にて各成分の含有量よ
り定義されるAr3 変態点以上の温度で圧延を終了し、圧
延終了からAr3 変態点−100 ℃の温度までを2 T 以上の
磁場中で冷却し、その後室温まで空冷あるいは加速冷却
することを特徴とする強度・靱性に優れた厚鋼板の製造
方法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1)3. C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 to 2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less And O: 0.0040 to 0.0150 wt%, Ti: 0.01 to 0.15 wt% REM: 0.0010 to 0.0200 wt%, Ca: 0.0010 to 0.0100 wt%, and the balance is Fe and After heating and soaking the steel consisting of unavoidable impurities above the Ar 3 transformation point,
Hot rolling is performed, and at that time, the rolling is completed at a temperature equal to or higher than the Ar 3 transformation point defined by the content of each component in Equation (1), and from the end of the rolling to the temperature of the Ar 3 transformation point −100 ° C. Is cooled in a magnetic field of 2 T or more, and then cooled to room temperature by air or accelerated cooling. Ar 3 (° C) = 910-230C + 25Si-74Mn-56Ni-16Cr-9Mo-5Cu-1620Nb ... (1)
び不可避的不純物からなる鋼をAr3 変態点以上に加熱・
均熱した後、熱間圧延を施し、その際に式(1) にて各成
分の含有量より定義されるAr3 変態点以上の温度で圧延
を終了し、圧延終了からAr3 変態点−100 ℃の温度まで
を2 T 以上の磁場中で冷却し、その後室温まで空冷ある
いは加速冷却することを特徴とする強度・靱性に優れた
厚鋼板の製造方法。 Ar3(℃) = 910− 230C+25Si−74Mn−56Ni−16Cr−9Mo−5Cu−1620Nb …… (1)4. C: 0.05 to 0.18 wt%, Si: 0.05 to 0.6 wt%, Mn: 0.60 to 2.00 wt%, Al: 0.005 to 0.050 wt%, P: 0.020 wt% or less, S: 0.015 wt% or less And O: 0.0040 to 0.0150 wt%, Ti: 0.01 to 0.15 wt% REM: 0.0010 to 0.0200 wt%, Ca: 0.0010 to 0.0100 wt%, and one or more of the following: Cu: 0.05 to 2.0 wt%, Ni: 0.05 to 0.60 wt%, Nb: 0.003 to 0.020 wt%, Cr: 0.05 to 0.50 wt%, Mo: 0.02 to 0.10 wt% B: 0.0002 to 0.0020 wt%, V: 0.04 to 0.15 wt%, and at least one of the group consisting of N: 0.0050 to 0.0150 wt%, the balance being Fe and inevitable Heat the steel consisting of impurities above the Ar 3 transformation point
After soaking, hot rolling is performed.At that time, rolling is completed at a temperature equal to or higher than the Ar 3 transformation point defined by the content of each component in Equation (1), and from the end of rolling, the Ar 3 transformation point − A method for manufacturing thick steel sheets with excellent strength and toughness, characterized by cooling to a temperature of 100 ° C in a magnetic field of 2 T or more, and then cooling to room temperature by air or accelerated cooling. Ar 3 (° C) = 910-230C + 25Si-74Mn-56Ni-16Cr-9Mo-5Cu-1620Nb ... (1)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17682197A JPH1121625A (en) | 1997-07-02 | 1997-07-02 | Production of thick steel plate excellent in strength and toughness |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP17682197A JPH1121625A (en) | 1997-07-02 | 1997-07-02 | Production of thick steel plate excellent in strength and toughness |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH1121625A true JPH1121625A (en) | 1999-01-26 |
Family
ID=16020441
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP17682197A Withdrawn JPH1121625A (en) | 1997-07-02 | 1997-07-02 | Production of thick steel plate excellent in strength and toughness |
Country Status (1)
Country | Link |
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JP (1) | JPH1121625A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001234240A (en) * | 1999-12-17 | 2001-08-28 | Kawasaki Steel Corp | Method for controlling structure of dual-phase steel |
JP2007327099A (en) * | 2006-06-07 | 2007-12-20 | Nippon Steel Corp | Thick steel plate having excellent toughness in high-heat input weld heat affected zone |
JP2009120957A (en) * | 2002-06-19 | 2009-06-04 | Nippon Steel Corp | Steel for crude oil tank, production method thereof, crude oil tank and method for preventing corrosion thereof |
CN103352166A (en) * | 2013-06-07 | 2013-10-16 | 马钢(集团)控股有限公司 | High-strength magnetic-conductive steel plate and producing method thereof |
-
1997
- 1997-07-02 JP JP17682197A patent/JPH1121625A/en not_active Withdrawn
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001234240A (en) * | 1999-12-17 | 2001-08-28 | Kawasaki Steel Corp | Method for controlling structure of dual-phase steel |
JP2009120957A (en) * | 2002-06-19 | 2009-06-04 | Nippon Steel Corp | Steel for crude oil tank, production method thereof, crude oil tank and method for preventing corrosion thereof |
JP2007327099A (en) * | 2006-06-07 | 2007-12-20 | Nippon Steel Corp | Thick steel plate having excellent toughness in high-heat input weld heat affected zone |
JP4505434B2 (en) * | 2006-06-07 | 2010-07-21 | 新日本製鐵株式会社 | Thick steel plate with excellent toughness of heat affected zone |
CN103352166A (en) * | 2013-06-07 | 2013-10-16 | 马钢(集团)控股有限公司 | High-strength magnetic-conductive steel plate and producing method thereof |
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