JP2953919B2 - Slab for high toughness and high strength steel and method for producing rolled section steel using the slab - Google Patents
Slab for high toughness and high strength steel and method for producing rolled section steel using the slabInfo
- Publication number
- JP2953919B2 JP2953919B2 JP22615293A JP22615293A JP2953919B2 JP 2953919 B2 JP2953919 B2 JP 2953919B2 JP 22615293 A JP22615293 A JP 22615293A JP 22615293 A JP22615293 A JP 22615293A JP 2953919 B2 JP2953919 B2 JP 2953919B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- slab
- composite oxide
- rem
- rolling
- 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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- Heat Treatment Of Steel (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、建造物の構造部材とし
て用いられる形鋼の降伏点範囲を保証し、耐震性能に優
れた高靱性高強度鋼用鋳片及びその鋳片を素材とする圧
延形鋼の製造法に係わるものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slab for high-toughness and high-strength steel which guarantees a yield point range of a shaped steel used as a structural member of a building and has excellent seismic performance, and a slab for the slab. It relates to a method for producing a rolled section steel.
【０００２】[0002]
【従来の技術】建築物の超高層化、安全規準の厳格化な
どから、柱および梁に用いられる鋼材、例えば特に板厚
の大きなサイズのＨ形鋼（以下、極厚Ｈ形鋼と称す）に
は、一層の高強度化、高靱性化、低降伏比化が求められ
ている。このような要求特性を満たすために、従来は圧
延終了後に焼準処理などの熱処理を施すことが行われ
た。熱処理の付加は熱処理コストと生産効率の低下など
大幅なコスト上昇を招き、経済性に問題があった。この
課題を解決するためには圧延ままで高性能の材質特性を
得られるように、新しい合金設計、製造法の開発が必要
となった。2. Description of the Related Art Steel materials used for columns and beams, for example, H-beams having a particularly large thickness (hereinafter, referred to as extremely thick H-beams) have been used to increase the height of buildings and stricter safety standards. Are required to have higher strength, higher toughness and lower yield ratio. In order to satisfy such required characteristics, conventionally, a heat treatment such as a normalizing process has been performed after the completion of rolling. The addition of heat treatment causes a significant increase in cost, such as a decrease in heat treatment cost and production efficiency, and has a problem in economy. To solve this problem, it was necessary to develop a new alloy design and manufacturing method so that high-performance material properties could be obtained as-rolled.
【０００３】一般に、フランジを有する形鋼、例えばＨ
形鋼をユニバーサル圧延により製造すると、圧延造形上
の制約およびその形状の特異性からウエブ、フランジお
よびフランジとウエブの結合部（フィレット部）の各部
位で圧延仕上げ温度、圧下率、冷却速度に差を生じる。
その結果、部位間に強度、延性、靱性のバラつきが発生
し、例えば溶接構造用圧延鋼材（ＪＩＳ Ｇ３１０６）
等の規準に満たない部位が生じる。Generally, a section steel having a flange, for example, H
When a section steel is manufactured by universal rolling, differences in the rolling finish temperature, rolling reduction, and cooling rate at each part of the web, the flange, and the joint (fillet) between the flange and the web due to the limitations of rolling molding and the peculiarity of the shape. Is generated.
As a result, variations in strength, ductility, and toughness occur between the portions, for example, a rolled steel material for a welded structure (JIS G3106).
Some parts do not meet the criteria.
【０００４】特に極厚Ｈ形鋼の素材に連続鋳造スラブを
用いる場合には、連続鋳造設備で製造可能なスラブ最大
厚みに限界があるため、低圧下比となる。さらに、圧延
造形上の寸法精度の制約から板厚の厚いフランジ部は高
温圧延となり、圧延終了後の鋼材冷却は徐冷となって、
ミクロ組織は粗粒化する。ＴＭＣＰによる細粒化法があ
るが、造形上の制約から形鋼圧延では鋼板の製造法のよ
うな大圧下はできない。また、厚鋼板分野ではＶＮの析
出効果を利用し高強度・高靱性鋼を製造する、例えば特
公昭６２−５０５４８号公報、特公昭６２−５４８６２
号公報の技術が提案されているが、溶鋼を従来法による
Ａｌ脱酸処理をしているため鋼中の固溶不純物元素の例
えばＮ，Ｐ，Ｓを化合物とし完全には固定できない。そ
のため、高強度化すると中心偏析帯に不純物元素と合金
元素が濃縮し、ＵＳＴ欠陥が発現すると同時に著しい靱
性低下を招くこととなる。即ち、従来のＡｌ脱酸におけ
るＡｌ単独とその量では溶鋼中に生成するアルミナは安
定なコランダム結晶構造を有するＡｌ2 Ｏ3 であり窒化
物、燐化物、硫化物の優先析出サイトとしての機能を有
しない。[0004] In particular, when a continuous cast slab is used as a material of an extremely thick H-section steel, the maximum thickness of the slab that can be manufactured by the continuous casting facility is limited, so that the reduction ratio is low. In addition, the thick flange part is hot rolled due to the restriction of the dimensional accuracy in the roll molding, and the steel material cooling after the rolling is gradually cooled,
The microstructure coarsens. Although there is a grain refining method by TMCP, due to restrictions on molding, it is not possible to perform a large reduction in the shape steel rolling as in the method of manufacturing a steel sheet. In the field of thick steel plates, high strength and high toughness steels are produced by utilizing the precipitation effect of VN. For example, Japanese Patent Publication No. Sho 62-50548 and Japanese Patent Publication No. Sho 62-54862.
However, since molten steel is subjected to Al deoxidation treatment by a conventional method, it cannot be completely fixed as a compound of, for example, N, P, and S, which are solid solution impurity elements in the steel. Therefore, when the strength is increased, the impurity element and the alloy element are concentrated in the central segregation zone, which causes UST defects to occur and at the same time causes a significant decrease in toughness. In other words, in the conventional Al deoxidation alone and with the amount of Al, the alumina generated in the molten steel is Al 2 O 3 having a stable corundum crystal structure, and functions as a preferential precipitation site for nitride, phosphide, and sulfide. Do not have.
【０００５】[0005]
【発明が解決しようとする課題】前記の課題を解決する
ためには、製鋼過程の成分調整と添加手順の工夫により
スピネル結晶構造の複合酸化物を必要な数だけ晶出させ
た鋳片を製造する必要がある。その他に、Ｈ形鋼のフィ
レット部はＣＣスラブの中心偏析部と一致し、この部位
に存在するＭｎＳは低温圧延条件下では著しく延伸し、
板厚方向の絞り値を低下させ、溶接時にラメラティアを
生じる場合がある。このように従来の技術では目的の信
頼性の高い高強度高靱性の圧延形鋼をオンラインで製造
し安価に提供することは困難である。In order to solve the above-mentioned problems, a cast slab in which a required number of complex oxides having a spinel crystal structure are crystallized by adjusting the components in the steelmaking process and devising the addition procedure. There is a need to. In addition, the fillet part of the H-section steel coincides with the center segregation part of the CC slab, and MnS present in this part is significantly elongated under low-temperature rolling conditions,
In some cases, the drawing value in the thickness direction is reduced, and lamella tearing occurs during welding. As described above, it is difficult for the conventional technology to manufacture the desired highly reliable high-strength, high-toughness rolled section steel online and provide it at low cost.
【０００６】[0006]
【課題を解決するための手段】本発明鋳片は、製鋼工程
での多量ＡｌとＣａ，Ｍｇ，ＲＥＭの添加により窒化
物、燐化物、硫化物の優先析出サイトとして作用するよ
うに、陽イオン空孔の格子欠陥を持つスピネル結晶構造
の複合酸化物に変化させることにより、この酸化物上に
不純物固溶元素を化合物とし析出させ固定することを可
能にしたものである。また、本発明鋳片を素材とするこ
とにより、ＴＭＣＰの大圧下圧延に代わり軽圧下の熱間
圧延においても十分に組織の細粒化が可能なように圧延
パス間での水冷により高靱性高強度鋼用を得ることを特
徴とするものである。SUMMARY OF THE INVENTION The slab of the present invention is prepared by adding a large amount of Al, Ca, Mg, and REM in a steelmaking process so that the slab acts as a preferential precipitation site for nitrides, phosphides, and sulfides. By changing to a composite oxide having a spinel crystal structure having lattice defects of vacancies, it becomes possible to precipitate and fix an impurity solute element as a compound on this oxide. Further, by using the slab of the present invention as a raw material, high toughness can be obtained by water cooling between rolling passes so that the structure can be sufficiently refined even in hot rolling under light rolling instead of large rolling under TMCP. It is characterized in that it is used for high strength steel.
【０００７】その要旨とするところは下記のとうりであ
る。 重量％で、Ｃ：０．０４〜０．２０％、Ｓｉ：０．
０１〜０．５０％、Ｍｎ：０．４〜２．０％、Ｐ：０．
０２％以下、Ｓ：０．０１５％以下、Ｎ：０．００５％
以下、Ａｌ：０．１１〜０．３０％の組成の溶鋼に、
０．００１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含
有するようにＣａ：０．０１％以下、Ｍｇ：０．０１％
以下、ＲＥＭ：０．０１％以下のいずれかの１種または
２種以上を添加し、残部がＦｅおよび不可避不純物から
なる溶鋼に溶製し、溶鋼の凝固温度から９００℃間を
０．６〜２０℃／Ｓの冷却速度で冷却、鋳造し、鋳片中
にＡｌ−Ｃａ系複合酸化物、Ａｌ−Ｍｇ系複合酸化物、
Ａｌ−ＲＥＭ系複合酸化物、Ａｌ−Ｃａ−Ｍｇ系複合酸
化物、Ａｌ−Ｃａ−ＲＥＭ系複合酸化物、Ａｌ−Ｍｇ−
ＲＥＭ系複合酸化物およびＡｌ−Ｃａ−Ｍｇ−ＲＥＭ系
複合酸化物の総数が２０個／mm2 以上晶出分散させた高
靱性高強度鋼用鋳片。 重量％で、Ｃ：０．０４〜０．２０％、Ｓｉ：０．
０１〜０．５０％、Ｍｎ：０．４〜２．０％、Ｐ：０．
０２％以下、Ｓ：０．０１５％以下、Ｎ：０．００５％
以下、Ａｌ：０．１１〜０．３０％の組成の溶鋼に、
０．００１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含
有するようにＣａ：０．０１％以下、Ｍｇ：０．０１％
以下、ＲＥＭ：０．０１％以下のいずれかの１種または
２種以上を添加し、加えてＮｂ：０．０５％以下、Ｖ：
０．１％以下、Ｔｉ：０．０３％以下、Ｂ：０．００３
以下のいずれかの１種または２種以上を含有し、残部が
Ｆｅおよび不可避不純物からなる溶鋼に溶製し、溶鋼の
凝固温度から９００℃間を０．６〜２０℃／Ｓの冷却速
度で冷却、鋳造し、鋳片中にＡｌ−Ｃａ系複合酸化物、
Ａｌ−Ｍｇ系複合酸化物、Ａｌ−ＲＥＭ系複合酸化物、
Ａｌ−Ｃａ−Ｍｇ系複合酸化物、Ａｌ−Ｃａ−ＲＥＭ系
複合酸化物、Ａｌ−Ｍｇ−ＲＥＭ系複合酸化物およびＡ
ｌ−Ｃａ−Ｍｇ−ＲＥＭ系複合酸化物の総数が２０個／
mm2 以上晶出分散させた高靱性高強度鋼用鋳片。 重量％で、Ｃ：０．０４〜０．２０％、Ｓｉ：０．
０１〜０．５０％、Ｍｎ：０．４〜２．０％、Ｐ：０．
０２％以下、Ｓ：０．０１５％以下、Ｎ：０．００５％
以下、Ａｌ：０．１１〜０．３０％の組成の溶鋼に、
０．００１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含
有するようにＣａ：０．０１％以下、Ｍｇ：０．０１％
以下、ＲＥＭ：０．０１％以下のいずれかの１種または
２種以上を添加し、加えてＣｒ：１．０％以下、Ｍｏ：
１．０％以下、Ｎｉ：３．０％以下、Ｃｕ：１．０％以
下のいずれかの１種または２種以上を含有し、残部がＦ
ｅおよび不可避不純物からなる溶鋼に溶製し、溶鋼の凝
固温度から９００℃間を０．６〜２０℃／Ｓの冷却速度
で冷却、鋳造し、鋳片中にＡｌ−Ｃａ系複合酸化物、Ａ
ｌ−Ｍｇ系複合酸化物、Ａｌ−ＲＥＭ系複合酸化物、Ａ
ｌ−Ｃａ−Ｍｇ系複合酸化物、Ａｌ−Ｃａ−ＲＥＭ系複
合酸化物、Ａｌ−Ｍｇ−ＲＥＭ系複合酸化物およびＡｌ
−Ｃａ−Ｍｇ−ＲＥＭ系複合酸化物の総数が２０個／mm
2 以上晶出分散させた高靱性高強度鋼用鋳片。 重量％で、Ｃ：０．０４〜０．２０％、Ｓｉ：０．
０１〜０．５０％、Ｍｎ：０．４〜２．０％、Ｐ：０．
０２％以下、Ｓ：０．０１５％以下、Ｎ：０．００５％
以下、Ａｌ：０．１１〜０．３０％の組成の溶鋼に、
０．００１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含
有するようにＣａ：０．０１％以下、Ｍｇ：０．０１％
以下、ＲＥＭ：０．０１％以下のいずれかの１種または
２種以上を添加し、加えてＮｂ：０．０５％以下、Ｖ：
０．１％以下、Ｔｉ：０．０３％以下、Ｂ：０．００３
以下のいずれかの１種または２種以上を含有し、さらに
Ｃｒ：１．０％以下、Ｍｏ：１．０％以下、Ｎｉ：３．
０％以下、Ｃｕ：１．０％以下のいずれかの１種または
２種以上を含有し、残部がＦｅおよび不可避不純物から
なる溶鋼に溶製し、溶鋼の凝固温度から９００℃間を
０．６〜２０℃／Ｓの冷却速度で冷却、鋳造し、鋳片中
にＡｌ−Ｃａ系複合酸化物、Ａｌ−Ｍｇ系複合酸化物、
Ａｌ−ＲＥＭ系複合酸化物、Ａｌ−Ｃａ−Ｍｇ系複合酸
化物、Ａｌ−Ｃａ−ＲＥＭ系複合酸化物、Ａｌ−Ｍｇ−
ＲＥＭ系複合酸化物およびＡｌ−Ｃａ−Ｍｇ−ＲＥＭ系
複合酸化物の総数が２０個／mm2 以上晶出分散させた高
靱性高強度鋼用鋳片。 前記項記載の鋳片を１１００〜１３００℃の温度
域に再加熱後に圧延を開始し、圧延工程で鋼片表層部の
温度を７００℃以下に水冷し、パス間の復熱過程で圧延
する工程を一回以上繰り返し圧延し、圧延終了後に１〜
３０℃／ｓの冷却速度で６５０〜４００℃まで冷却し放
冷する高靱性高強度圧延形鋼の製造方法。 前記項記載の鋳片を１１００〜１３００℃の温度
域に再加熱後に圧延を開始し、圧延工程で鋼片表層部の
温度を７００℃以下に水冷し、パス間の復熱過程で圧延
する工程を一回以上繰り返し圧延し、圧延終了後に１〜
３０℃／ｓの冷却速度で６５０〜４００℃まで冷却し放
冷する高靱性高強度圧延形鋼の製造方法。 前記項記載の鋳片を１１００〜１３００℃の温度
域に再加熱後に圧延を開始し、圧延工程で鋼片表層部の
温度を７００℃以下に水冷し、パス間の復熱過程で圧延
する工程を一回以上繰り返し圧延し、圧延終了後に１〜
３０℃／ｓの冷却速度で６５０〜４００℃まで冷却し放
冷する高靱性高強度圧延形鋼の製造方法。 前記項記載の鋳片を１１００〜１３００℃の温度
域に再加熱後に圧延を開始し、圧延工程で鋼片表層部の
温度を７００℃以下に水冷し、パス間の復熱過程で圧延
する工程を一回以上繰り返し圧延し、圧延終了後に１〜
３０℃／ｓの冷却速度で６５０〜４００℃まで冷却し放
冷する高靱性高強度圧延形鋼の製造方法。The summary is as follows. By weight%, C: 0.04 to 0.20%, Si: 0.
01-0.50%, Mn: 0.4-2.0%, P: 0.
02% or less, S: 0.015% or less, N: 0.005%
Hereinafter, in molten steel having a composition of Al: 0.11 to 0.30%,
Ca: 0.01% or less, Mg: 0.01% so as to contain 0.001% ≦ Ca + Mg + REM ≦ 0.030%
Hereinafter, one or more kinds of REM: 0.01% or less are added, and the remainder is melted into molten steel composed of Fe and unavoidable impurities. Cooling and casting at a cooling rate of 20 ° C./S, Al-Ca-based composite oxide, Al-Mg-based composite oxide,
Al-REM complex oxide, Al-Ca-Mg complex oxide, Al-Ca-REM complex oxide, Al-Mg-
REM-based complex oxide and Al-Ca-Mg-REM-based high-toughness and high strength steel for slabs total number of composite oxide was 20 / mm 2 or more for crystallization dispersed. By weight%, C: 0.04 to 0.20%, Si: 0.
01-0.50%, Mn: 0.4-2.0%, P: 0.
02% or less, S: 0.015% or less, N: 0.005%
Hereinafter, in molten steel having a composition of Al: 0.11 to 0.30%,
Ca: 0.01% or less, Mg: 0.01% so as to contain 0.001% ≦ Ca + Mg + REM ≦ 0.030%
Hereinafter, one or more of REM: 0.01% or less is added, and Nb: 0.05% or less, V:
0.1% or less, Ti: 0.03% or less, B: 0.003
One or more of the following are contained, and the balance is melted into molten steel composed of Fe and unavoidable impurities, and from the solidification temperature of the molten steel to 900 ° C at a cooling rate of 0.6 to 20 ° C / S. Cooling, casting, Al-Ca based composite oxide in the slab,
Al-Mg based composite oxide, Al-REM based composite oxide,
Al-Ca-Mg-based composite oxide, Al-Ca-REM-based composite oxide, Al-Mg-REM-based composite oxide and A
The total number of l-Ca-Mg-REM composite oxides is 20 /
A slab for high-toughness and high-strength steel with crystallization dispersion of 2 mm or more. By weight%, C: 0.04 to 0.20%, Si: 0.
01-0.50%, Mn: 0.4-2.0%, P: 0.
02% or less, S: 0.015% or less, N: 0.005%
Hereinafter, in molten steel having a composition of Al: 0.11 to 0.30%,
Ca: 0.01% or less, Mg: 0.01% so as to contain 0.001% ≦ Ca + Mg + REM ≦ 0.030%
Hereinafter, one or more of REM: 0.01% or less are added, and Cr: 1.0% or less, Mo:
1.0% or less, Ni: 3.0% or less, Cu: 1.0% or less.
e and unavoidable impurities are melted, and then cooled and cast at a cooling rate of 0.6 to 20 ° C./S from 900 ° C. to a solidification temperature of the molten steel, and Al-Ca-based composite oxide is contained in a slab. A
l-Mg composite oxide, Al-REM composite oxide, A
l-Ca-Mg-based composite oxide, Al-Ca-REM-based composite oxide, Al-Mg-REM-based composite oxide and Al
-The total number of Ca-Mg-REM-based composite oxides is 20 / mm
A slab for high-toughness and high-strength steel in which two or more crystallizations are dispersed. By weight%, C: 0.04 to 0.20%, Si: 0.
01-0.50%, Mn: 0.4-2.0%, P: 0.
02% or less, S: 0.015% or less, N: 0.005%
Hereinafter, in molten steel having a composition of Al: 0.11 to 0.30%,
Ca: 0.01% or less, Mg: 0.01% so as to contain 0.001% ≦ Ca + Mg + REM ≦ 0.030%
Hereinafter, one or more of REM: 0.01% or less is added, and Nb: 0.05% or less, V:
0.1% or less, Ti: 0.03% or less, B: 0.003
One or two or more of the following, Cr: 1.0% or less, Mo: 1.0% or less, Ni: 3.
0% or less, Cu: 1.0% or less, containing one or more kinds, and the balance is melted into molten steel composed of Fe and unavoidable impurities. Cooling and casting at a cooling rate of 6 to 20 ° C./S, Al-Ca-based composite oxide, Al-Mg-based composite oxide,
Al-REM complex oxide, Al-Ca-Mg complex oxide, Al-Ca-REM complex oxide, Al-Mg-
REM-based complex oxide and Al-Ca-Mg-REM-based high-toughness and high strength steel for slabs total number of composite oxide was 20 / mm 2 or more for crystallization dispersed. A step of starting rolling after reheating the slab of the above paragraph to a temperature range of 1100 to 1300 ° C, water-cooling the surface of the slab to 700 ° C or less in a rolling step, and rolling in a reheating process between passes. Is rolled repeatedly one or more times.
A method for producing a high-toughness high-strength rolled steel that is cooled to 650 to 400 ° C. at a cooling rate of 30 ° C./s and left to cool. A step of starting rolling after reheating the slab of the above paragraph to a temperature range of 1100 to 1300 ° C, water-cooling the surface of the slab to 700 ° C or less in a rolling step, and rolling in a reheating process between passes. Is rolled repeatedly one or more times.
A method for producing a high-toughness high-strength rolled steel that is cooled to 650 to 400 ° C. at a cooling rate of 30 ° C./s and left to cool. A step of starting rolling after reheating the slab of the above paragraph to a temperature range of 1100 to 1300 ° C, water-cooling the surface temperature of the slab to 700 ° C or less in a rolling process, and rolling in a reheating process between passes. Is rolled repeatedly one or more times.
A method for producing a high-toughness high-strength rolled steel that is cooled to 650 to 400 ° C. at a cooling rate of 30 ° C./s and left to cool. A step of starting rolling after reheating the slab of the above paragraph to a temperature range of 1100 to 1300 ° C, water-cooling the surface temperature of the slab to 700 ° C or less in a rolling process, and rolling in a reheating process between passes. Is rolled repeatedly one or more times.
A method for producing a high-toughness high-strength rolled steel that is cooled to 650 to 400 ° C. at a cooling rate of 30 ° C./s and left to cool.
【０００８】[0008]
【作用】以下、本発明について詳細に説明する。先ず、
本発明鋼の成分範囲の限定理由について述べる。Ｃは鋼
の強度を向上させる有効な成分として添加するもので、
０．０４％未満では構造用鋼として必要な強度が得られ
ず、また、０．２０％を超える過剰の含有は、母材靱
性、溶接割れ性、ＨＡＺ靱性などを著しく低下させるの
で、上限を０．２０％とした。Hereinafter, the present invention will be described in detail. First,
The reasons for limiting the composition range of the steel of the present invention will be described. C is added as an effective component to improve the strength of steel,
If the content is less than 0.04%, the strength required for structural steel cannot be obtained, and if the content exceeds 0.20%, the base material toughness, weld cracking property, HAZ toughness, etc. are significantly reduced. 0.20%.
【０００９】Ｓｉは母材の強度確保、脱酸などに必要で
あるが、０．５０％を超えると溶接熱影響部に硬化組織
の高炭素マルテンサイトを生成し、靱性を低下させる。
また、０．０１％未満では脱酸不足となるためにＳｉ含
有量を０．０１〜０．３０％に制限した。Ｍｎは母材の
強度、靱性を確保するために０．４％以上の含有を必要
とするが、溶接部の靱性、割れ性などの特性を満たす必
要から上限を２．０％とした。[0009] Si is necessary for securing the strength of the base material and deoxidizing, but when it exceeds 0.50%, high carbon martensite having a hardened structure is generated in the heat affected zone of the weld, and the toughness is reduced.
If the content is less than 0.01%, deoxidation becomes insufficient, so the Si content is limited to 0.01 to 0.30%. Mn needs to be contained at least 0.4% in order to secure the strength and toughness of the base material, but the upper limit is set to 2.0% because it is necessary to satisfy properties such as toughness and cracking of the welded portion.
【００１０】Ｐは固溶体強化し降伏点を上昇させ靱性を
低下させ、また連続鋳造鋳片の中心偏析を生じＵＳＴ欠
陥を発生するので、できるだけ低減する必要があるが
０．０２％以下にすればその影響は少ないので上限を
０．０２％とした。ＳはＭｎＳを生成し、このＭｎＳは
熱間圧延により延伸し、ＵＳＴ欠陥、ラメラティアを生
じる。ＭｎＳの生成はＳ量が０．０１５％以下ではＣ
ａ，Ｍｇ，ＲＥＭを添加し延伸しない硫化化合物組成に
改質することができるが、Ｓが０．０１５％を超える
と、この硫化物の増加によりＵＳＴ欠陥、ラメラティア
を発生させ改善できないので０．０１５％以下とした。Since P strengthens solid solution, raises the yield point and lowers the toughness, and causes segregation in the center of the continuous cast slab to generate UST defects, it is necessary to reduce P as much as possible. Since the influence is small, the upper limit is set to 0.02%. S generates MnS, and the MnS is stretched by hot rolling to cause UST defects and lamella tear. MnS is produced when the amount of S is 0.015% or less.
a, Mg, and REM can be added to modify the sulfide compound composition without stretching. However, if S exceeds 0.015%, UST defects and lamellar tears are generated due to the increase in sulfide, and the content cannot be improved. 015% or less.
【００１１】Ｎは製鋼過程で、できるだけ固溶Ｎを低減
させることが基本であるが製鋼における経済性と、Ａｌ
Ｎ，ＴｉＮとして固定可能な限界量とから、その上限を
０．００５％とした。次に、ＡｌはＡｌ系複合酸化物を
生成させるために添加するものである。析出物の優先析
出サイトして効果を発揮させるのには、全Ａｌで０．１
１％未満ではＣａ，Ｍｇ，ＲＥＭの安定な添加ができ
ず、また析出物の優先析出サイトとして効果を発揮する
組成の複合酸化物が生成できないため０．１１％以上と
した。０．３０％を超えると、これらの効果が飽和する
ことと、粗大なＡｌ2 Ｏ3 を多数生成し、靱性の低下を
生じるために上限を０．３０％とした。[0011] In the steel making process, it is fundamental to reduce N as much as possible in the steel making process.
The upper limit is set to 0.005% based on the limit amounts that can be fixed as N and TiN. Next, Al is added to generate an Al-based composite oxide. In order to exhibit the effect as a preferential precipitation site of precipitates, it is necessary to use 0.1% in total Al.
If it is less than 1%, stable addition of Ca, Mg, and REM cannot be performed, and a composite oxide having a composition exhibiting an effect as a preferential precipitation site of a precipitate cannot be formed. If it exceeds 0.30%, these effects are saturated, and a large number of coarse Al 2 O 3 are generated, and the toughness is reduced, so the upper limit is set to 0.30%.
【００１２】つぎにＡｌ酸化物とＣａ，Ｍｇ，ＲＥＭと
の活性な複合酸化物を生成させるためにはＣａ，Ｍｇ，
ＲＥＭの１種または２種以上を添加する必要がある。こ
れらの元素の効果は各元素の重量％で０．０１％を超え
る添加ではＡｌ酸化物より脱酸力の強い安定なＣａ，Ｍ
ｇ，ＲＥＭの酸化物を生成し、Ａｌ酸化物とこれらの元
素との活性な複合酸化物の生成し得なくなるために、こ
れらの元素の各添加量を０．０１％以下に制限した。ま
たＣａ＋Ｍｇ＋ＲＥＭの総量を０．００１〜０．０３０
％に限定したのは、総量で０．０３０％以上添加する
と、大きさ３μｍ以上の粗大な酸化物を生成し靱性と延
性を著しく劣化させるためであり、０．００１未満では
活性な複合酸化物が生成できないためである。Next, in order to produce an active composite oxide of Al oxide and Ca, Mg, REM, Ca, Mg,
One or more REMs need to be added. The effect of these elements is that when added in an amount exceeding 0.01% by weight of each element, stable Ca, M having stronger deoxidizing power than Al oxide is obtained.
g, REM oxides were formed, and an active composite oxide of Al oxide and these elements could not be formed. Therefore, the amount of each of these elements was limited to 0.01% or less. Further, the total amount of Ca + Mg + REM is 0.001 to 0.030.
The reason for limiting the amount to 0.03% is that, when added in a total amount of 0.030% or more, a coarse oxide having a size of 3 μm or more is generated and the toughness and ductility are remarkably deteriorated. Cannot be generated.
【００１３】加えて、上記の組成に、制御圧延による圧
延組織制御をおこない母材の強度、靱性を得る目的か
ら、マイクロアロイ元素のＮｂ，Ｖ，Ｔｉ，Ｂの１種ま
たは２種以上を添加することができる。Ｎｂ，Ｖ，Ｔ
ｉ，Ｂは微量添加により圧延組織を微細化できることか
ら低合金化でき溶接特性を向上できる。しかしながら、
これらの元素の過剰な添加は溶接部の硬化や、母材の高
降伏点化をもたらすので、各々の含有量の上限をＮｂ：
０．０５％、Ｖ：０．１％、Ｔｉ：０．０３％、Ｂ：
０．００３％とした。In addition, one or more of the microalloy elements Nb, V, Ti, and B are added to the above composition for the purpose of controlling the rolling structure by controlled rolling and obtaining the strength and toughness of the base material. can do. Nb, V, T
Since i and B can refine the rolling structure by adding a small amount, it is possible to reduce the alloy and improve the welding characteristics. However,
Excessive addition of these elements leads to hardening of the weld and an increase in the yield point of the base metal.
0.05%, V: 0.1%, Ti: 0.03%, B:
0.003%.
【００１４】さらに、本発明鋼の組成に、母材強度、靱
性を得る目的で、Ｃｒ，Ｍｏ，Ｎｉ，Ｃｕの１種または
２種以上を添加することができる。Ｃｒ，Ｍｏは主に母
材の高強度化のために添加するものであるが、各々が
１．０％を超えると溶接熱影響部を硬化し溶接割れ性を
高めるために上限を１．０％とした。Further, one or more of Cr, Mo, Ni, and Cu can be added to the composition of the steel of the present invention for the purpose of obtaining base metal strength and toughness. Cr and Mo are mainly added for increasing the strength of the base material, but if each exceeds 1.0%, the upper limit is set to 1.0 in order to harden the heat-affected zone and increase the weld cracking resistance. %.
【００１５】Ｎｉ，Ｃｕは強度を高めると同時に靱性を
高め有効であるが、Ｎｉが３％を超えるとベイナイトを
生成し明瞭な降伏点が得られなくなるために上限を３％
とした。Ｃｕは１％を超えると熱間圧延時に表面傷を生
じ易くなるために上限を１％とした。次に、これらの組
成の溶鋼の凝固温度から９００℃間を０．６〜２０℃／
Ｓの冷却速度で冷却、鋳造するとしたのは鋳片中にＡｌ
系複合酸化物を２０個／mm2以上晶出させるために行う
ものであり、冷却速度０．６℃／Ｓ未満の緩冷却ではＡ
ｌ系複合酸化物は凝集粗大化し、２０個／mm2 未満とな
り靱性、延性を低下させるため冷却速度を０．６℃／Ｓ
以上とした。また上限を２０℃／Ｓとしたのは鋳片のこ
れ以上の急冷は現状の鋳造による鋳片では限界である。Ni and Cu are effective in increasing strength and toughness at the same time as increasing strength. However, if Ni exceeds 3%, bainite is formed and a clear yield point cannot be obtained, so the upper limit is 3%.
And If Cu exceeds 1%, surface flaws are likely to occur during hot rolling, so the upper limit was made 1%. Next, from the solidification temperature of the molten steel having these compositions, between 900 ° C and 0.6-20 ° C /
The reason for cooling and casting at the cooling rate of S is that Al
This is carried out in order to crystallize at least 20 composite oxides / mm 2 , and A at a slow cooling rate of less than 0.6 ° C./S.
The l-type composite oxide is agglomerated and coarsened to become less than 20 particles / mm 2, and the cooling rate is set to 0.6 ° C./S to reduce toughness and ductility.
It was above. The reason why the upper limit is set to 20 ° C./S is that quenching of the slab further than this is the limit in the slab by current casting.
【００１６】また、鋳片にＡｌ系複合酸化物が２０個／
mm2 以上含む必要の理由について述べる。製品の材質特
性は製鋼、鋳造工程に支配される先天的因子の鋳片の凝
固組織、成分偏析、本発明の微細複合酸化物、析出物等
と、圧延、ＴＭＣＰ、熱処理工程等により支配される後
天的因子のミクロ組織により決定される。当然、この先
天的因子である鋳片の性質は後の工程に継承される。本
発明の特徴はこの鋳片の先天的因子を制御することにあ
り、鋳片中に異相析出の優先析出サイトとして機能する
組成のＡｌ系複合酸化物を生成させ含ませることであ
る。この分散個数が２０個／mm2 未満では酸化物上に析
出する窒化物、燐化物、硫化物の析出サイト数として不
十分で、母相の固溶Ｎ，Ｐ，Ｓの固定ができないためで
ある。The cast slab contains 20 Al-based composite oxides /
The reason for including mm 2 or more is described. The material properties of the product are governed by the ingot solidification structure, component segregation, the fine composite oxides and precipitates of the present invention, and the rolling, TMCP, heat treatment processes, etc., which are innate factors governed by the steelmaking and casting processes. Determined by the microstructure of acquired factors. Naturally, the property of the slab, which is this innate factor, is inherited by the subsequent steps. The feature of the present invention is to control the innate factor of the slab, and to generate and include in the slab an Al-based composite oxide having a composition functioning as a preferential precipitation site for heterophase precipitation. If the dispersion number is less than 20 / mm 2, the number of nitride, phosphide, and sulfide precipitation sites deposited on the oxide is insufficient, and the solid solution N, P, and S in the mother phase cannot be fixed. is there.
【００１７】なお、酸化物個数はＸ線マイクロアナライ
ザー（ＥＰＭＡ）で測定し決定したものである。さて、
上記の本発明による複合酸化物を含む鋳片を形鋼の素材
として用いると、極めて高品質の高靱性・高強度の形鋼
が得られる。以下、その形鋼の製造手段を説明する。The number of oxides is determined by measuring with an X-ray microanalyzer (EPMA). Now,
When the slab containing the composite oxide according to the present invention described above is used as a material for a shaped steel, an extremely high-quality shaped steel with high toughness and high strength can be obtained. Hereinafter, means for producing the shaped steel will be described.
【００１８】上記の処理を経た鋳片は１１００〜１３０
０℃の温度域に再加熱する。この温度域に再加熱温度を
限定したのは、熱間加工による形鋼の製造には塑性変形
を容易にするため１１００℃以上の加熱が必要であり、
その上限は加熱炉の性能、経済性から１３００℃とし
た。加熱した鋳片は粗圧延、中間圧延、仕上げ圧延の各
工程により圧延造形されるが、本発明法の圧延工程にお
ける特徴は、中間圧延機において、圧延パス間で、鋳片
表層部の温度を７００℃以下に冷却し、鋼材表面が復熱
する過程で熱間圧延を行うことを少なくとも中間圧延工
程で１回以上行うことである。これは圧延パス間の水冷
により、鋼片の表層部から内部にかけ温度勾配を付与
し、低圧下条件においても内部への加工を浸透させるた
めと、低温圧延により生じるパス間待ち時間を短縮し、
効率的に行うためである。水冷と復熱圧延の繰り返し数
は被圧延材の厚みの大きさ、例えばＨ形鋼の場合ではフ
ランジの厚みに応じ、厚みが大きい場合には複数回行
う。ここで鋼片表層部の温度を７００℃以下に限定し冷
却する理由は、圧延に引き続き加速冷却するため、通常
のγ温度域からの冷却では表層部に、焼きが入り、硬化
相を生成し、加工性を損ねるためである。即ち７００℃
以下に冷却すれば、一旦γ／α変態温度を切り、次の圧
延するまでに表層部は復熱昇温し、低温γかγ／α二相
共存温度域での加工となり、焼き入性を著しく低減で
き、加速冷却による表面層の焼き入れ硬化を防止でき
る。The slab that has undergone the above treatment is 1100 to 130
Reheat to a temperature range of 0 ° C. The reason for limiting the reheating temperature to this temperature range is that the production of a shaped steel by hot working requires heating at 1100 ° C. or more to facilitate plastic deformation.
The upper limit was set to 1300 ° C. in view of the performance and economy of the heating furnace. The heated slab is roll-formed by the steps of rough rolling, intermediate rolling, and finish rolling.A feature of the rolling process of the present invention is that, in the intermediate rolling mill, between the rolling passes, the temperature of the surface layer of the slab is controlled. Cooling to 700 ° C. or lower and performing hot rolling in the process of recovering the surface of the steel material are performed at least once in the intermediate rolling step. This is to provide a temperature gradient from the surface layer of the slab to the inside by water cooling between rolling passes, and to penetrate the processing inside even under low pressure reduction conditions, and to reduce the waiting time between passes caused by low temperature rolling,
This is for efficient operation. The number of repetitions of the water cooling and recuperation rolling depends on the thickness of the material to be rolled, for example, in the case of an H-section steel, depending on the thickness of the flange. Here, the reason for limiting the temperature of the surface portion of the slab to 700 ° C. or less and cooling it is that, because of accelerated cooling following rolling, the surface layer is quenched by cooling from a normal γ temperature range to generate a hardened phase. This is because the workability is impaired. That is, 700 ° C
If cooled below, the γ / α transformation temperature is once cut off, and the surface layer is reheated and heated before the next rolling, and processing is performed in the low-temperature γ or γ / α two-phase coexisting temperature range. The quenching and hardening of the surface layer due to accelerated cooling can be significantly reduced.
【００１９】また、圧延終了後、引続き、１〜３０℃／
ｓの冷却速度で６５０〜４００℃まで冷却し終了するの
は、加速冷却によりフェライトの粒成長の抑制とパーラ
イト及びベイナイト組織比率を増加させ、低合金で目標
の強度を得るためであり、６５０〜４００℃で加速冷却
を停止するのは、６５０℃超での加速冷却の停止では、
Ａｒ1 点以上となり、一部γ相が残存し、フェライトの
粒成長の抑制とパーライト及びベイナイト組織比率を増
加させることができないため、６５０℃以下とした。ま
た、４００℃未満の冷却では、その後の放冷によりフェ
ライト相に過飽和に固溶しているＣを炭化物として析出
させることができず、フェライト相の延性が低下するた
め、この温度範囲に限定した。以下に本発明について実
施例に基づいて説明する。After the end of the rolling, the temperature is maintained at 1 to 30 ° C. /
The reason for cooling to 650 to 400 ° C. at the cooling rate of s and terminating the purpose is to suppress the grain growth of ferrite and increase the pearlite and bainite structure ratio by accelerated cooling to obtain the target strength with a low alloy, Stopping accelerated cooling at 400 ° C. is because stopping accelerated cooling above 650 ° C.
The Ar temperature was 1 point or more, a part of the γ phase remained, and it was impossible to suppress the ferrite grain growth and increase the pearlite and bainite structure ratios. Further, when the cooling is performed at a temperature lower than 400 ° C., it is impossible to precipitate supersaturated solid solution in the ferrite phase as carbide by cooling after that, and the ductility of the ferrite phase is reduced. . Hereinafter, the present invention will be described based on examples.
【００２０】[0020]
【実施例】試作形鋼は転炉溶製し、合金を添加後、Ｃ
ａ，Ｍｇのそれぞれの合金とＲＥＭを添加し、連続鋳造
により２００〜３００mm厚鋳片に鋳造した後、粗圧延工
程の図示は省略しているが、図１に示すユニバーサル圧
延装置列でＨ形鋼に圧延した。なお、鋳造後の冷却速度
はスラブの冷却帯の水量と鋳片の引き抜き速度の選択に
より制御した。[Example] A prototype steel was melted in a converter and added with an alloy.
After the respective alloys of a and Mg and REM were added and cast into a slab having a thickness of 200 to 300 mm by continuous casting, the rough rolling process is not shown, but the H-shape is used in the universal rolling mill row shown in FIG. Rolled into steel. The cooling rate after casting was controlled by selecting the amount of water in the cooling zone of the slab and the speed of drawing the slab.
【００２１】フランジ外面水冷は中間圧延機４の前後に
水冷装置５ａを設け、圧延パス間でのスプレー冷却とリ
バース圧延の繰り返と仕上げユニバーサル圧延機６で圧
延を終了した後、仕上げユニバーサル圧延機の後面に設
けた冷却装置５ｂでスプレー冷却した。機械特性は図２
に示すフランジ２の板厚ｔ2 の中心部（１／２ｔ2 ）で
フランジ幅全長（Ｂ）の１／４，１／２幅（１／４Ｂ，
１／２Ｂ）から、ウェブ３の板厚中心部でウェブ高さの
１／２Ｈから試験片を採集し求めた。なお、これらの箇
所の特性を求めたのはフランジ１／４Ｆ部とウェブ１／
２Ｗ部はフランジ部とウェブ部の各々の平均的な機械特
性を示し、フランジ１／２Ｆ部はその特性が最も低下す
るので、これら三箇所によりＨ形鋼の機械試験特性を代
表できるとしたためである。なお、フランジ１／２Ｆ部
の板厚方向の引張り試験における絞り値が最も低下し、
耐ラメラティア特性の指標となるのでこの部位の絞り値
を示した。For water cooling on the outer surface of the flange, water cooling devices 5a are provided before and after the intermediate rolling mill 4, and after repeating the spray cooling and the reverse rolling between the rolling passes and finishing the rolling by the finishing universal rolling mill 6, the finishing universal rolling mill Was spray-cooled by a cooling device 5b provided on the rear surface of the device. Figure 2 shows mechanical properties
At the center (1 / 2t 2 ) of the thickness t 2 of the flange 2 shown in FIG.
ＢB), a test piece was collected from ＨH of the web height at the center of the thickness of the web 3 to obtain a test piece. The characteristics of these locations were determined by the flange 1 / 4F section and the web 1 /
The 2W portion shows the average mechanical properties of the flange portion and the web portion, and the flange 1 / 2F portion has the most deteriorated properties. Therefore, it is assumed that these three locations can represent the mechanical test characteristics of the H-section steel. is there. In addition, the aperture value in the tensile test in the thickness direction of the flange 1 / 2F portion is the lowest,
The aperture value of this portion is shown because it is an index of the lamella tear resistance.
【００２２】表１，２、表３，４には、試作鋼の化学成
分値、凝固時の冷却速度と鋳片中のＡｌ系酸化物個数を
示す。Tables 1, 2 and 3 and 4 show the chemical composition of the trial steel, the cooling rate during solidification, and the number of Al-based oxides in the slab.
【００２３】[0023]
【表１】 [Table 1]
【００２４】[0024]
【表２】 [Table 2]
【００２５】[0025]
【表３】 [Table 3]
【００２６】[0026]
【表４】 [Table 4]
【００２７】表５，６、表７，８には、圧延条件とフラ
ンジ水冷の有無などの製造条件に対する、Ｈ形鋼の各部
の機械試験特性を示す。なお、圧延加熱温度を１２８０
℃に揃えたのは、一般的に加熱温度の低下は機械特性を
向上させることは周知であり、高温加熱条件は機械特性
の最低値を示すと推定され、この値がそれ以下の加熱温
度での特性を代表できると判断したためである。Tables 5, 6, 7 and 8 show the mechanical test characteristics of each part of the H-section steel with respect to rolling conditions and production conditions such as the presence or absence of flange water cooling. In addition, the rolling heating temperature was set to 1280.
It is well known that lowering the heating temperature generally improves the mechanical properties, and it is estimated that the high-temperature heating condition indicates the lowest value of the mechanical properties, and this value is set at a lower heating temperature. This is because it has been determined that the characteristic can be represented.
【００２８】[0028]
【表５】 [Table 5]
【００２９】[0029]
【表６】 [Table 6]
【００３０】[0030]
【表７】 [Table 7]
【００３１】[0031]
【表８】 [Table 8]
【００３２】表５，６、表７，８に示すように、本発明
による鋼１〜７、鋼Ａｌ〜Ａ５は、目標の降伏点範囲が
ＪＩＳ規格の下限値＋８０Ｎ／mm2 内のＳＭ４９０では
ＹＰ＝３２５〜４０５Ｎ／mm2 、ＳＭ５２０ではＹＰ＝
３３５〜４１５Ｎ／mm2 、ＳＭ５７０ではＹＰ＝４３０
〜５１０Ｎ／mm2 に制御され、しかも、降伏比（ＹＰ／
ＴＳ）も０．８以下の低ＹＲ値を満たし、抗張力（前記
ＪＩＳＧ３１０６）と−１０℃でのシャルピー衝撃値４
７（Ｊ）以上を十分に満たしている。一方、比較鋼の鋼
８と鋼Ｂ２はＡｌとＣａが添加されており組成は本発明
を満たすので１／２Ｆ部の絞り値の目標値２５％以上を
超えるが、凝固後の冷却速度が０．３℃／ｓで、冷却速
度範囲以下となり、Ａｌ系複合酸化物個数が不足し、母
相の固溶Ｎ，Ｐ等の低減と粒内フェライト生成が不十分
で細粒化できないため、１／２Ｆ部の靱性が目標値のｖ
Ｅ−１０≧４７Ｊをクリアーできない。比較鋼の鋼９〜
鋼１１と鋼Ｂ１は通常のＡｌ脱酸でＣａ，Ｍｇ，ＲＥＭ
が添加されておらず、Ａｌ系の複合酸化物個数が不足
し、１／２Ｆ部の絞り値と衝撃値が目標を達成できな
い。鋼１２、鋼Ｂ３、鋼Ｂ４は低Ｓであるので、１／２
Ｆ部の絞り値は目標を満たすが、１／２Ｆ部の衝撃値が
目標を達成できない。鋼１１はＡｌ添加量は満たしてい
るが、Ｃａ，Ｍｇ，ＲＥＭが添加されておらず、安定な
アルミナのみとなり、活性なＡｌ系複合酸化物が生成で
きないために１／２Ｆ部の絞り値と衝撃値が目標を達成
できない。加えて、鋼１１と鋼Ｂ２は圧延中水冷工程が
付加されていず、圧延後の加速冷却の冷却速度も小さく
降伏点がＳＭ４９０のＹＰ＝３２５〜４０５Ｎ／mm2 の
下限以下となる。As shown in Tables 5, 6, 7, and 8, steels 1 to 7 and steels A to A5 according to the present invention have a target yield point range of SM490 within the lower limit of JIS standard +80 N / mm 2 . YP = 325-405 N / mm 2 , YP = SM-520
335-415 N / mm 2 , YP = 430 for SM570
５１０510 N / mm 2 and the yield ratio (YP /
TS) also satisfies the low YR value of 0.8 or less, and has a tensile strength (the above-mentioned JISG3106) and a Charpy impact value at −10 ° C. of 4
7 (J) or more is sufficiently satisfied. On the other hand, steels 8 and B2, which are comparative steels, contain Al and Ca and have a composition that satisfies the present invention. At 3 ° C./s, the cooling rate becomes lower than the cooling rate range, the number of Al-based composite oxides becomes insufficient, the reduction of solid solution N, P, etc. in the parent phase and the formation of intragranular ferrite are insufficient, so that fine grains cannot be formed. / 2F part toughness is the target value v
E-10 ≧ 47J cannot be cleared. Comparative steel 9 ~
Steel 11 and steel B1 were Ca, Mg, REM by normal Al deoxidation.
Is not added, the number of Al-based composite oxides is insufficient, and the aperture value and the impact value at the 1/2 F part cannot achieve the targets. Steel 12, steel B3 and steel B4 have low S, so
Although the aperture value of the F section satisfies the target, the impact value of the 1/2 F section cannot achieve the target. Steel 11 satisfies the amount of Al added, but Ca, Mg, and REM were not added, and only stable alumina was formed, and an active Al-based composite oxide could not be generated. Impact value cannot achieve target. In addition, the steel 11 and the steel B2 are not provided with a water cooling process during rolling, and the cooling rate of accelerated cooling after rolling is also small, and the yield point of SM490 is below the lower limit of YP = 325 to 405 N / mm 2 .
【００３３】即ち、本発明の要件が総て満たされた時
に、表５，６、表７，８に示される鋼１〜７、鋼Ａ１〜
Ａ５のように、圧延形鋼の狭幅降伏点、低降伏比と耐ラ
メラティア特性と高靱性を有する信頼性の高い高強度高
靱性形鋼が圧延ままで製造可能となる。なお、本発明が
対象とする圧延形鋼は上記実施例のＨ形鋼に限らずＩ形
鋼、山形鋼、溝形鋼、不等辺不等厚山形鋼等のフランジ
を有する形鋼にも適用できることは勿論である。That is, when all the requirements of the present invention are satisfied, steels 1 to 7 and steels A1 to
As in A5, a highly reliable high-strength high-toughness section steel having a narrow yield point, a low yield ratio, lamella tear resistance and high toughness of a rolled section steel can be manufactured as it is rolled. The rolled section steel to which the present invention is applied is not limited to the H section steel of the above embodiment, but is also applicable to section steels having flanges such as I section steel, angle steel, channel steel, and unequal thickness angle steel. Of course, you can.
【００３４】[0034]
【発明の効果】本発明による鋳片と制御圧延法を適用し
た圧延形鋼は、建築用形鋼に要求される狭幅降伏点、低
降伏比と耐ラメラティア特性を達成でき、信頼性の高い
高強度高靱性形鋼がインラインで安価に製造と可能とな
り、大型鋼構造物用の鋼材の信頼性向上への寄与は極め
て大きい。As described above, the rolled section steel to which the slab according to the present invention and the controlled rolling method are applied can achieve the narrow width yield point, the low yield ratio and the lamella tear resistance required for the section steel for construction, and have high reliability. High-strength, high-toughness shaped steel can be manufactured in-line at low cost, and the contribution to the improvement of the reliability of steel materials for large-scale steel structures is extremely large.
【図面の簡単な説明】[Brief description of the drawings]
【図１】本発明法を実施する装置配置例の略図である。FIG. 1 is a schematic view of an example of an apparatus arrangement for performing the method of the present invention.
【図２】Ｈ形鋼の断面形状および機械試験片の採取位置
を示す図である。FIG. 2 is a diagram illustrating a cross-sectional shape of an H-section steel and a sampling position of a mechanical test piece.
１…Ｈ形鋼 ２…フランジ ３…ウェブ ４…中間圧延機 ５ａ…中間圧延機前後面の水冷装置 ５ｂ…仕上げ圧延機後面冷却装置 ６…仕上げ圧延機 DESCRIPTION OF SYMBOLS 1 ... H-shaped steel 2 ... Flange 3 ... Web 4 ... Intermediate rolling mill 5a ... Water cooling device of the front and back surface of an intermediate rolling mill 5b ... Finishing rolling machine rear cooling device 6 ... Finishing rolling mill
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.6，ＤＢ名) C22C 33/04 C21D 8/00 C22C 38/00 - 38/60 ──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. 6 , DB name) C22C 33/04 C21D 8/00 C22C 38/00-38/60
Claims (8)
１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含有するよ
うにＣａ：０．０１％以下、Ｍｇ：０．０１％以下、Ｒ
ＥＭ：０．０１％以下のいずれかの１種または２種以上
を添加し、残部がＦｅおよび不可避不純物からなる溶鋼
に溶製し、溶鋼の凝固温度から９００℃間を０．６〜２
０℃／Ｓの冷却速度で冷却、鋳造し、鋳片中にＡｌ−Ｃ
ａ系複合酸化物、Ａｌ−Ｍｇ系複合酸化物、Ａｌ−ＲＥ
Ｍ系複合酸化物、Ａｌ−Ｃａ−Ｍｇ系複合酸化物、Ａｌ
−Ｃａ−ＲＥＭ系複合酸化物、Ａｌ−Ｍｇ−ＲＥＭ系複
合酸化物およびＡｌ−Ｃａ−Ｍｇ−ＲＥＭ系複合酸化物
の総数が２０個／mm2 以上晶出分散させたことを特徴と
する高靱性高強度鋼用鋳片。C: 0.04 to 0.20%, Si: 0.01 to 0.50%, Mn: 0.4 to 2.0%, P: 0.02% or less by weight%, S : 0.015% or less, N: 0.005% or less Al: 0.001% to 0.30%
Ca: 0.01% or less, Mg: 0.01% or less, so that 1% ≦ Ca + Mg + REM ≦ 0.030%
EM: One or two or more of 0.01% or less are added, and the balance is melted into molten steel composed of Fe and unavoidable impurities.
Cooling and casting at a cooling rate of 0 ° C / S, and Al-C
a-based composite oxide, Al-Mg-based composite oxide, Al-RE
M-based composite oxide, Al-Ca-Mg-based composite oxide, Al
The total number of Ca-REM-based composite oxides, Al-Mg-REM-based composite oxides and Al-Ca-Mg-REM-based composite oxides is not less than 20 / mm < 2 >; A slab for tough high-strength steel.
１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含有するよ
うにＣａ：０．０１％以下、Ｍｇ：０．０１％以下、Ｒ
ＥＭ：０．０１％以下のいずれかの１種または２種以上
を添加し、加えてＮｂ：０．０５％以下、Ｖ：０．１％
以下、Ｔｉ：０．０３％以下、Ｂ：０．００３以下のい
ずれかの１種または２種以上を含有し、残部がＦｅおよ
び不可避不純物からなる溶鋼に溶製し、溶鋼の凝固温度
から９００℃間を０．６〜２０℃／Ｓの冷却速度で冷
却、鋳造し、鋳片中にＡｌ−Ｃａ系複合酸化物、Ａｌ−
Ｍｇ系複合酸化物、Ａｌ−ＲＥＭ系複合酸化物、Ａｌ−
Ｃａ−Ｍｇ系複合酸化物、Ａｌ−Ｃａ−ＲＥＭ系複合酸
化物、Ａｌ−Ｍｇ−ＲＥＭ系複合酸化物およびＡｌ−Ｃ
ａ−Ｍｇ−ＲＥＭ系複合酸化物の総数が２０個／mm2 以
上晶出分散させたことを特徴とする高靱性高強度鋼用鋳
片。2. In% by weight, C: 0.04 to 0.20%, Si: 0.01 to 0.50%, Mn: 0.4 to 2.0%, P: 0.02% or less, S : 0.015% or less, N: 0.005% or less Al: 0.001% to 0.30%
Ca: 0.01% or less, Mg: 0.01% or less, so that 1% ≦ Ca + Mg + REM ≦ 0.030%
One or more of EM: 0.01% or less is added, and Nb: 0.05% or less, V: 0.1%
Hereinafter, one or two or more of Ti: 0.03% or less and B: 0.003 or less are contained, and the balance is melted into molten steel composed of Fe and unavoidable impurities. At a cooling rate of 0.6 to 20 ° C./S, casting, and Al-Ca-based composite oxide, Al-
Mg-based composite oxide, Al-REM-based composite oxide, Al-
Ca-Mg composite oxide, Al-Ca-REM composite oxide, Al-Mg-REM composite oxide, and Al-C
A slab for high-toughness and high-strength steel, wherein the total number of a-Mg-REM-based composite oxides is crystallized and dispersed at least 20 / mm 2 .
１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含有するよ
うにＣａ：０．０１％以下、Ｍｇ：０．０１％以下、Ｒ
ＥＭ：０．０１％以下のいずれかの１種または２種以上
を添加し、加えてＣｒ：１．０％以下、Ｍｏ：１．０％
以下、Ｎｉ：３．０％以下、Ｃｕ：１．０％以下のいず
れかの１種または２種以上を含有し、残部がＦｅおよび
不可避不純物からなる溶鋼に溶製し、溶鋼の凝固温度か
ら９００℃間を０．６〜２０℃／Ｓの冷却速度で冷却、
鋳造し、鋳片中にＡｌ−Ｃａ系複合酸化物、Ａｌ−Ｍｇ
系複合酸化物、Ａｌ−ＲＥＭ系複合酸化物、Ａｌ−Ｃａ
−Ｍｇ系複合酸化物、Ａｌ−Ｃａ−ＲＥＭ系複合酸化
物、Ａｌ−Ｍｇ−ＲＥＭ系複合酸化物およびＡｌ−Ｃａ
−Ｍｇ−ＲＥＭ系複合酸化物の総数が２０個／mm2 以上
晶出分散させたことを特徴とする高靱性高強度鋼用鋳
片。3. In% by weight, C: 0.04 to 0.20%, Si: 0.01 to 0.50%, Mn: 0.4 to 2.0%, P: 0.02% or less, S : 0.015% or less, N: 0.005% or less Al: 0.001% to 0.30%
Ca: 0.01% or less, Mg: 0.01% or less, so that 1% ≦ Ca + Mg + REM ≦ 0.030%
One or more of EM: 0.01% or less is added, and Cr: 1.0% or less, Mo: 1.0%
Hereinafter, one or more of Ni: 3.0% or less and Cu: 1.0% or less are contained, and the balance is melted into molten steel composed of Fe and unavoidable impurities. Cooling between 900 ° C at a cooling rate of 0.6 to 20 ° C / S,
Al-Ca based composite oxide, Al-Mg
Composite oxide, Al-REM composite oxide, Al-Ca
-Mg-based composite oxide, Al-Ca-REM-based composite oxide, Al-Mg-REM-based composite oxide and Al-Ca
High toughness and high strength billet steel for the total number of -mg-REM-based composite oxide is characterized in that was 20 / mm 2 or more for crystallization dispersed.
１％≦Ｃａ＋Ｍｇ＋ＲＥＭ≦０．０３０％を含有するよ
うにＣａ：０．０１％以下、Ｍｇ：０．０１％以下、Ｒ
ＥＭ：０．０１％以下のいずれかの１種または２種以上
を添加し、加えてＮｂ：０．０５％以下、Ｖ：０．１％
以下、Ｔｉ：０．０３％以下、Ｂ：０．００３以下のい
ずれかの１種または２種以上を含有し、さらにＣｒ：
１．０％以下、Ｍｏ：１．０％以下、Ｎｉ：３．０％以
下、Ｃｕ：１．０％以下のいずれかの１種または２種以
上を含有し、残部がＦｅおよび不可避不純物からなる溶
鋼に溶製し、溶鋼の凝固温度から９００℃間を０．６〜
２０℃／Ｓの冷却速度で冷却、鋳造し、鋳片中にＡｌ−
Ｃａ系複合酸化物、Ａｌ−Ｍｇ系複合酸化物、Ａｌ−Ｒ
ＥＭ系複合酸化物、Ａｌ−Ｃａ−Ｍｇ系複合酸化物、Ａ
ｌ−Ｃａ−ＲＥＭ系複合酸化物、Ａｌ−Ｍｇ−ＲＥＭ系
複合酸化物およびＡｌ−Ｃａ−Ｍｇ−ＲＥＭ系複合酸化
物の総数が２０個／mm2 以上晶出分散させたことを特徴
とする高靱性高強度鋼用鋳片。4. In% by weight, C: 0.04 to 0.20%, Si: 0.01 to 0.50%, Mn: 0.4 to 2.0%, P: 0.02% or less, S : 0.015% or less, N: 0.005% or less Al: 0.001% to 0.30%
Ca: 0.01% or less, Mg: 0.01% or less, so that 1% ≦ Ca + Mg + REM ≦ 0.030%
One or more of EM: 0.01% or less is added, and Nb: 0.05% or less, V: 0.1%
Hereinafter, one or more of Ti: 0.03% or less, B: 0.003 or less, and Cr:
1.0% or less, Mo: 1.0% or less, Ni: 3.0% or less, Cu: 1.0% or less, containing one or more of them, with the balance being Fe and inevitable impurities. From 900 to 900 ° C from the solidification temperature of molten steel.
Cooling and casting at a cooling rate of 20 ° C./S.
Ca-based composite oxide, Al-Mg-based composite oxide, Al-R
EM composite oxide, Al-Ca-Mg composite oxide, A
l-Ca-REM-based composite oxide, the total number of Al-Mg-REM-based complex oxide and Al-Ca-Mg-REM-based composite oxide is characterized in that it was 20 / mm 2 or more for crystallization dispersed A slab for high toughness and high strength steel.
０℃の温度域に再加熱後に圧延を開始し、圧延工程で鋼
片表層部の温度を７００℃以下に水冷し、パス間の復熱
過程で圧延する工程を一回以上繰り返し圧延し、圧延終
了後に１〜３０℃／ｓの冷却速度で６５０〜４００℃ま
で冷却し放冷することを特徴とする高靱性高強度圧延形
鋼の製造方法。5. The slab according to claim 1, wherein the slab is 1100 to 130.
Rolling is started after reheating to a temperature range of 0 ° C, and the temperature of the surface layer of the slab is water-cooled to 700 ° C or less in the rolling process, and the process of rolling in the recuperation process between passes is repeated one or more times. A method for producing a high-toughness and high-strength rolled steel, comprising cooling to 650 to 400 ° C. at a cooling rate of 1 to 30 ° C./s after completion, and allowing to cool.
０℃の温度域に再加熱後に圧延を開始し、圧延工程で鋼
片表層部の温度を７００℃以下に水冷し、パス間の復熱
過程で圧延する工程を一回以上繰り返し圧延し、圧延終
了後に１〜３０℃／ｓの冷却速度で６５０〜４００℃ま
で冷却し放冷することを特徴とする高靱性高強度圧延形
鋼の製造方法。6. The slab according to claim 2, wherein the slab is 1100 to 130.
Rolling is started after reheating to a temperature range of 0 ° C, and the temperature of the surface layer of the slab is water-cooled to 700 ° C or less in the rolling process, and the process of rolling in the recuperation process between passes is repeated one or more times. A method for producing a high-toughness and high-strength rolled steel, comprising cooling to 650 to 400 ° C. at a cooling rate of 1 to 30 ° C./s after completion, and allowing to cool.
０℃の温度域に再加熱後に圧延を開始し、圧延工程で鋼
片表層部の温度を７００℃以下に水冷し、パス間の復熱
過程で圧延する工程を一回以上繰り返し圧延し、圧延終
了後に１〜３０℃／ｓの冷却速度で６５０〜４００℃ま
で冷却し放冷することを特徴とする高靱性高強度圧延形
鋼の製造方法。7. The slab according to claim 3, wherein the slab is 1100 to 130.
Rolling is started after reheating to a temperature range of 0 ° C, and the temperature of the surface layer of the slab is water-cooled to 700 ° C or less in the rolling process, and the process of rolling in the recuperation process between passes is repeated one or more times. A method for producing a high-toughness and high-strength rolled steel, comprising cooling to 650 to 400 ° C. at a cooling rate of 1 to 30 ° C./s after completion, and allowing to cool.
０℃の温度域に再加熱後に圧延を開始し、圧延工程で鋼
片表層部の温度を７００℃以下に水冷し、パス間の復熱
過程で圧延する工程を一回以上繰り返し圧延し、圧延終
了後に１〜３０℃／ｓの冷却速度で６５０〜４００℃ま
で冷却し放冷することを特徴とする高靱性高強度圧延形
鋼の製造方法。8. The slab according to claim 4, wherein the slab is 1100 to 130.
Rolling is started after reheating to a temperature range of 0 ° C, and the temperature of the surface layer of the slab is water-cooled to 700 ° C or less in the rolling process, and the process of rolling in the recuperation process between passes is repeated one or more times. A method for producing a high-toughness and high-strength rolled steel, comprising cooling to 650 to 400 ° C. at a cooling rate of 1 to 30 ° C./s after completion, and allowing to cool.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22615293A JP2953919B2 (en) | 1993-09-10 | 1993-09-10 | Slab for high toughness and high strength steel and method for producing rolled section steel using the slab |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22615293A JP2953919B2 (en) | 1993-09-10 | 1993-09-10 | Slab for high toughness and high strength steel and method for producing rolled section steel using the slab |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0776751A JPH0776751A (en) | 1995-03-20 |
| JP2953919B2 true JP2953919B2 (en) | 1999-09-27 |
Family
ID=16840679
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22615293A Expired - Fee Related JP2953919B2 (en) | 1993-09-10 | 1993-09-10 | Slab for high toughness and high strength steel and method for producing rolled section steel using the slab |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2953919B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100635074B1 (en) * | 1999-12-28 | 2006-10-16 | 주식회사 포스코 | A method for production of the high strength and toughness steel by coarse precipitate |
| KR100482208B1 (en) | 2000-11-17 | 2005-04-21 | 주식회사 포스코 | Method for manufacturing steel plate having superior toughness in weld heat-affected zone by nitriding treatment |
| WO2002044436A1 (en) * | 2000-12-01 | 2002-06-06 | Posco | Steel plate to be precipitating tin+mns for welded structures, method for manufacturing the same and welding fabric using the same |
| WO2002048417A1 (en) * | 2000-12-14 | 2002-06-20 | Posco | STEEL PLATE TO BE PRECIPITATING TiN + ZrN FOR WELDED STRUCTURES, METHOD FOR MANUFACTURING THE SAME AND WELDING FABRIC USING THE SAME |
| JP3821036B2 (en) * | 2002-04-01 | 2006-09-13 | 住友金属工業株式会社 | Hot rolled steel sheet, hot rolled steel sheet and cold rolled steel sheet |
-
1993
- 1993-09-10 JP JP22615293A patent/JP2953919B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0776751A (en) | 1995-03-20 |
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