JPH08283902A - Rolled shape steel for refractory use and its production - Google Patents
Rolled shape steel for refractory use and its productionInfo
- Publication number
- JPH08283902A JPH08283902A JP8961795A JP8961795A JPH08283902A JP H08283902 A JPH08283902 A JP H08283902A JP 8961795 A JP8961795 A JP 8961795A JP 8961795 A JP8961795 A JP 8961795A JP H08283902 A JPH08283902 A JP H08283902A
- Authority
- JP
- Japan
- Prior art keywords
- less
- rolling
- steel
- weight
- molten steel
- 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.)
- Granted
Links
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
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
て用いられる耐火性、靭性の優れたＨ形鋼等フランジを
有する圧延形鋼と制御圧延による圧延形鋼の製造方法に
係わるものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolled section steel having a flange such as an H-section steel having excellent fire resistance and toughness, which is used as a structural member of a building, and a method for producing rolled section steel by controlled rolling. is there.
【０００２】[0002]
【従来の技術】建築物の超高層化、建築設計技術の高度
化などから耐火設計の見直しが建設省総合プロジェクト
により行われ、昭和６２年３月に「新耐火設計法」が制
定された。この規定により、旧法令による火災時に鋼材
の温度を３５０℃以下にするように耐火被覆するとした
制限が解除され、鋼材の高温強度と建築物の実荷重との
かねあいにより、それに適合する耐火被覆方法を決定で
きるようになった。即ち６００℃での設計高温強度を確
保できる場合はそれに見合い耐火被覆を削減できるよう
になった。2. Description of the Related Art The fire resistant design was reviewed by a Ministry of Construction comprehensive project due to the super-rise of buildings and the sophistication of building design technology, and the "New Fire Resistant Design Law" was enacted in March 1987. Under this regulation, the restriction of fireproof coating to keep the temperature of steel materials to 350 ° C or less at the time of fire under the old law was lifted, and due to the balance between high-temperature strength of steel materials and actual load of buildings, a fireproof coating method suitable for it You can now decide. That is, when the designed high temperature strength at 600 ° C. can be secured, the fireproof coating can be reduced accordingly.
【０００３】このような動向に対応し、先に特開平２−
７７５２３号公報の耐火性の優れた建築用低降伏比鋼お
よび鋼材並びにその製造方法が提案されている。この先
願発明の要旨は６００℃での降伏点が常温時の７０％以
上となるようにＭｏ、Ｎｂを添加し高温強度を向上させ
たものである。鋼材の設計高温強度を６００℃に設定し
たのは、合金元素による鋼材費の上昇とそれによる耐火
被覆施工費との兼ね合いから最も経済的であるという知
見に基づいたものである。In response to such a trend, Japanese Patent Laid-Open No. 2-
Japanese Patent No. 77523 discloses a low yield ratio steel for construction having excellent fire resistance, a steel material, and a manufacturing method thereof. The gist of the invention of this prior application is to improve the high temperature strength by adding Mo and Nb so that the yield point at 600 ° C. becomes 70% or more of that at room temperature. The reason why the design high temperature strength of the steel material is set to 600 ° C. is based on the finding that it is the most economical in view of the balance between the increase of the steel material cost due to the alloying element and the fire protection coating construction cost due to it.
【０００４】また、従来は鋼のＡｌ脱酸は溶製過程の初
期段階でＡｌ添加され、溶鋼の脱酸と生成したＡｌ2 Ｏ
3 を浮上分離し高清浄化することを目的にしていた。即
ち、如何に溶鋼の酸素濃度を下げ、鋼中の粗大な一次脱
酸酸化物個数を減らすかに主題がおかれていた。Further, in the past, Al deoxidation of steel was performed by adding Al in the initial stage of the melting process to deoxidize molten steel and form Al 2 O.
The purpose was to float and separate 3 to make it highly clean. That is, the theme was how to reduce the oxygen concentration of the molten steel and reduce the number of coarse primary deoxidized oxides in the steel.
【０００５】[0005]
【発明が解決しようとする課題】本発明者等は前述の先
願技術によって製造された鋼材を各種の形鋼、特に複雑
な形状から厳しい圧延造形上の制約を有するＨ形鋼の素
材に適用することを試みた結果、ウエブ、フランジ、フ
ィレットの各部位での圧延仕上げ温度、圧下率、冷却速
度に差が生じることから、部位により組織、特にベイナ
イト割合が著しく異なり、常温・高温強度、延性、靭性
がバラツキ、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た。また、粒内フェライトの生成
による組織微細化では、フェライトの組織割合が比較的
高い成分では効果的であるが、ベイナイトの割合が高く
なると組織の微細化が困難となる欠点があった。The inventors of the present invention applied the steel materials manufactured by the above-mentioned prior art to various shaped steels, particularly H-shaped steels having complicated restrictions due to severe rolling shaping. As a result, there was a difference in the rolling finish temperature, rolling reduction and cooling rate at each part of the web, flange and fillet. , The toughness varied, and there were some parts that did not meet the criteria such as rolled steel for welded structures (JIS G3106). Further, in the refinement of the structure due to the formation of intragranular ferrite, it is effective in the component having a relatively high proportion of the structure of ferrite, but there is a defect that the refinement of the structure becomes difficult when the proportion of bainite is high.
【０００６】上記の課題を解決するためには、圧延時の
加熱温度１２００〜１３００℃でもγ粒径をＡＳＴＭ
Ｎｏ. で６番以上に細粒化ができればベイナイト割合の
高い組織でも組織微細化が可能となるので、このγ細粒
化法の開発が課題となる。この目的を達成するには高温
で分解せず安定に存在する微細な析出物を分散分布さ
せ、これにより成長するγ粒界をピンニングし、γ粒成
長を抑制し細粒化する方法が考えられれる。本発明はこ
の析出物として微細なＭｇ系酸化物が効果的であること
を見出しこれらを微細晶出させた鋼を開発することを指
向した。In order to solve the above-mentioned problems, the γ grain size is set to ASTM even at a heating temperature of 1200 to 1300 ° C. during rolling.
If the grain size of No. 6 or more can be refined, the microstructure can be refined even in the structure having a high bainite ratio, so the development of this γ refinement method is an issue. In order to achieve this purpose, a method is considered in which fine precipitates that do not decompose at high temperature and exist stably are dispersed and distributed, thereby pinning the γ grain boundaries that grow, and suppressing γ grain growth and making the grains finer. Be done. The present invention has found that fine Mg-based oxides are effective as these precipitates, and aimed to develop a steel in which these finely crystallized crystals are finely crystallized.
【０００７】本発明は従来の発想とは異なり、製鋼過程
における脱酸剤の選択、その添加順序及び凝固過程の冷
却制御により酸化物の組成とサイズ、分散密度を制御
し、生成させた酸化物を異相析出の優先析出サイトとし
活用する点にある。本願出願人は先に特願平６−１１７
０５号で、前記酸化物を粒内フェライト変態核として機
能させ、粒内フェライトの生成により組織を微細し、Ｈ
形鋼の部位間の材質特性の均質化と高靭性化を達成する
手段を提案した。本発明はこれとは異なり、高温安定性
の高い微細なＭｇ系酸化物（主としてＭｇＯ）を高密度
分散させ、これらの析出物を圧延加熱時の１２００〜１
３００℃でのγ粒の粒成長を抑制するためのピンニング
サイトととして機能させ、γ粒の細粒化により組織を微
細化することによりＨ形鋼の部位間の材質特性の均質化
と高靭性・高温高強度化を達成することを特徴としてい
る。Unlike the conventional idea, the present invention controls the composition, size and dispersion density of the oxide by selecting the deoxidizing agent in the steel making process, controlling the addition order of the deoxidizing agent and cooling the solidification process. Is used as a preferential precipitation site for heterophasic precipitation. The applicant of the present application previously filed Japanese Patent Application No. 6-117.
In No. 05, the oxide is made to function as an intragranular ferrite transformation nucleus, and the structure is refined by the formation of intragranular ferrite.
A means to achieve homogenization of material properties and toughness between sections of shaped steel was proposed. Unlike the above, the present invention disperses a fine Mg-based oxide having high high-temperature stability (mainly MgO) at a high density, and deposits these precipitates in the rolling condition 1200 to 1
It functions as a pinning site to suppress the grain growth of γ grains at 300 ° C, and the fineness of the γ grains makes the structure finer, thereby homogenizing the material properties between parts of the H-section steel and achieving high toughness. -Characterized by achieving high temperature and high strength.
【０００８】また、製造法におけるＴＭＣＰの特徴は厚
鋼板で多く行われている低温・大圧下圧延とは異なり、
形鋼における軽圧下の熱間圧延においても効率的に組織
の細粒化が可能となるように圧延パス間で水冷し、水
冷、圧延、水冷とを繰り返す工程をとる方法にある。The characteristic of TMCP in the manufacturing method is different from the low temperature / large reduction rolling which is often performed on thick steel plates.
There is a method in which a step of performing water cooling between rolling passes and repeating water cooling, rolling, and water cooling is performed so that fine graining of the structure can be efficiently performed even in hot rolling under light pressure in shaped steel.
【０００９】[0009]
【課題を解決するための手段】本発明は、組織を微細化
することを目的とし、製鋼過程において適正な脱酸処
理を行い、溶鋼の高清浄化、溶存酸素濃度の規制、およ
びSi-Mg 合金及びNi-Mg 合金の添加を行い、微細なMg系
酸化物を含有させた鋳片を圧延しＨ形鋼としたものと、
該鋳片を素材として熱間圧延パス間で水冷することに
より、Ｈ形鋼のフランジの表面と内部に温度差を与え、
軽圧下条件下においても、より高温の内部への圧下浸透
を高め、α生成核となる加工転位を導入し、板厚中心部
での組織の微細化が達成できる圧延中水冷方法を開発し
た。加えて、圧延後のγ／α変態温度域を冷却制御する
ことにより、その核生成させたフェライトの粒成長を抑
制する方法によればミクロ組織の細粒化ができ、高能率
で製造コストの安価な耐火用圧延形鋼の生産が可能であ
ると言う知見に基づき前記課題を解決したもので、その
要旨とするところは、以下のとおりである。DISCLOSURE OF THE INVENTION The present invention aims at refining the microstructure, and performs appropriate deoxidation treatment in the steelmaking process to achieve high cleaning of molten steel, regulation of dissolved oxygen concentration, and Si-Mg alloy. And a Ni-Mg alloy were added, and a slab containing a fine Mg-based oxide was rolled into an H-section steel,
By water-cooling the slab as a raw material between hot rolling passes, a temperature difference is given to the surface and the inside of the flange of the H-section steel,
We have developed a water-cooling method during rolling that can enhance the infiltration into the interior at a higher temperature, introduce work dislocations that become α-forming nuclei, and achieve the refinement of the microstructure at the center of the plate thickness, even under light rolling conditions. In addition, by controlling the cooling of the γ / α transformation temperature range after rolling, the method of suppressing the grain growth of the nucleated ferrite can make the microstructure finer, resulting in high efficiency and high manufacturing cost. The above problems have been solved on the basis of the knowledge that inexpensive fire-resistant rolled steel can be produced, and the gist thereof is as follows.
【００１０】(1) 重量% で、C:0.04〜0.20% 、Si:0.05
〜0.50% 、Mn:0.4〜1.8%、Mo:0.4〜1.0%、N:0.004%以
下、Al:0.004% 以下、を含み、残部がFeおよび不可避不
純物からなる溶鋼を、予備脱酸処理によって、溶存酸素
を重量％で0.003 〜0.015%に調整後、Mg合金を添加し重
量％でMg:0.001〜0.005%に成分調整した溶鋼を鋳込んだ
鋳片内に大きさ３μｍ以下のMg系酸化物を50個/mm2以上
含有する鋳片を熱間圧延して製造した耐火用圧延形鋼。(1)% by weight, C: 0.04 to 0.20%, Si: 0.05
~ 0.50%, Mn: 0.4 ~ 1.8%, Mo: 0.4 ~ 1.0%, N: 0.004% or less, Al: 0.004% or less, the balance, the molten steel consisting of Fe and unavoidable impurities, by pre-deoxidation treatment, After adjusting dissolved oxygen to 0.003 to 0.015% by weight, Mg alloy was added to adjust the content of Mg to 0.001 to 0.005% by weight. Molten steel was cast into the slab and a Mg-based oxide of 3 μm or less in size was cast. fifty / mm 2 or more content to fire for rolled shape steel produced by hot rolling a slab.
【００１１】(2) 重量% で、C:0.04〜0.20% 、Si:0.05
〜0.50% 、Mn:0.4〜1.8%、Mo:0.4〜1.0%、N:0.004%以
下、Al:0.004% 以下、を含み、加えてCr:1.0% 以下、C
u：1.0%以下、Ni:2.0% 以下、Nb：0.04% 以下、V:0.1%
以下、Ti:0.025% 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を、
予備脱酸処理によって、溶存酸素を重量％で0.003 〜0.
015%に調整後、Mg合金を添加し重量％でMg:0.001〜0.00
5%に成分調整した該溶鋼を鋳込んだ鋳片内に大きさ３μ
ｍ以下のMg系酸化物を50個/mm2以上含有する鋳片を熱間
圧延して製造した耐火用圧延形鋼。(2) C: 0.04 to 0.20%, Si: 0.05% by weight
~ 0.50%, Mn: 0.4 to 1.8%, Mo: 0.4 to 1.0%, N: 0.004% or less, Al: 0.004% or less, in addition Cr: 1.0% or less, C
u: 1.0% or less, Ni: 2.0% or less, Nb: 0.04% or less, V: 0.1%
Hereinafter, molten steel containing one or more of Ti: 0.025% or less and the balance Fe and unavoidable impurities,
By pre-deoxidation treatment, the dissolved oxygen content is 0.003 to 0.
After adjusting to 015%, Mg alloy is added and Mg in weight% is 0.001-0.00
3μ in size in a slab containing the molten steel adjusted to 5% composition
A fire-resistant rolled shaped steel produced by hot rolling a slab containing 50 m / m 2 or more of Mg-based oxides / mm 2 or more.
【００１２】(3) 重量% で、C:0.04〜0.20% 、Si:0.05
〜0.50% 、Mn:0.4〜1.8%、Mo:0.4〜1.0%、N:0.004%以
下、Al:0.004% 以下、を含み、残部がFeおよび不可避不
純物からなる溶鋼を、予備脱酸処理によって、溶存酸素
を重量％で0.003 〜0.015%に調整後、Mg合金を添加し重
量％でMg:0.001〜0.005%に成分調整した溶鋼を鋳込んだ
鋳片を1200〜1300℃の温度域に再加熱後に圧延を開始
し、圧延工程で形鋼のフランジ表面温度を700 ℃以下に
水冷し、以降の圧延パス間の復熱過程で圧延する水冷・
圧延工程を一回以上繰り返し圧延し、圧延終了後に0.5
〜10℃/sの冷却速度で700 〜400 ℃まで冷却し放冷する
耐火用圧延形鋼の製造方法。(3)%: C: 0.04 to 0.20%, Si: 0.05
~ 0.50%, Mn: 0.4 ~ 1.8%, Mo: 0.4 ~ 1.0%, N: 0.004% or less, Al: 0.004% or less, the balance, the molten steel consisting of Fe and unavoidable impurities, by pre-deoxidation treatment, After adjusting the dissolved oxygen to 0.003 to 0.015% by weight, the Mg alloy is added, and the slab containing molten steel with the composition adjusted to Mg: 0.001 to 0.005% by weight is reheated to the temperature range of 1200 to 1300 ° C. After that, the rolling is started, the flange surface temperature of the shaped steel is water-cooled to 700 ° C or less in the rolling process, and is rolled in the recuperation process between subsequent rolling passes.
Repeat the rolling process one or more times, and finish rolling 0.5
A method for producing a fire-resistant rolled shaped steel, which comprises cooling to 700 to 400 ° C at a cooling rate of ~ 10 ° C / s and allowing it to cool.
【００１３】(4) 重量% で、C:0.04〜0.20% 、Si:0.05
〜0.50% 、Mn:0.4〜1.8%、Mo:0.4〜1.0%、N:0.004%以
下、Al:0.004% 以下、を含み、加えてCr:1.0% 以下、C
u：1.0%以下、Ni:2.0% 以下、Nb：0.04% 以下、V:0.1%
以下、Ti:0.025% 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を、
予備脱酸処理によって、溶存酸素を重量％で0.003 〜0.
015%に調整後、Mg合金を添加し重量％でMg:0.001〜0.00
5%に成分調整した該溶鋼を鋳込んだ鋳片を1200〜1300℃
の温度域に再加熱後に圧延を開始し、圧延工程で形鋼の
フランジ表面温度を700 ℃以下に水冷し、以降の圧延パ
ス間の復熱過程で圧延する水冷・圧延工程を一回以上繰
り返し圧延し、圧延終了後に0.5 〜10℃/sの冷却速度で
700 〜400 ℃まで冷却し放冷する耐火用圧延形鋼の製造
方法。(4)%: C: 0.04 to 0.20%, Si: 0.05
~ 0.50%, Mn: 0.4 to 1.8%, Mo: 0.4 to 1.0%, N: 0.004% or less, Al: 0.004% or less, in addition Cr: 1.0% or less, C
u: 1.0% or less, Ni: 2.0% or less, Nb: 0.04% or less, V: 0.1%
Hereinafter, molten steel containing one or more of Ti: 0.025% or less and the balance Fe and unavoidable impurities,
By pre-deoxidation treatment, the dissolved oxygen content is 0.003 to 0.
After adjusting to 015%, Mg alloy is added and Mg in weight% is 0.001-0.00
A slab containing the molten steel adjusted to a composition of 5% is 1200 to 1300 ° C.
Rolling is started after reheating to the above temperature range, the flange surface temperature of the shaped steel is water-cooled to 700 ° C or less in the rolling process, and the water-cooling / rolling process is repeated once or more in the reheating process between rolling passes. After rolling, after finishing rolling, at a cooling rate of 0.5-10 ℃ / s
A method for producing rolled rolled steel for refractory which is cooled to 700 to 400 ° C and allowed to cool.
【００１４】[0014]
【作用】以下、本発明について詳細に説明する。鋼材の
高温強度は鉄の融点のほぼ1/2 の温度の700 ℃以下では
常温での強化機構とほぼ同様であり、フェライト結晶
粒径の微細化、合金元素による固溶体強化、硬化相
による分散強化 微細析出物による析出強化等によっ
て支配される。一般に高温強度の上昇にはＭｏ、Ｃｒの
添加による析出強化と転位の消失抑制による高温での軟
化抵抗を高めることにより達成されている。しかしＭ
ｏ、Ｃｒの添加は著しく焼き入れ性を上げ、母材のフェ
ライト+ パーライト組織をベイナイト組織に変化させ
る。ベイナイト組織を生成し易い成分系鋼を圧延Ｈ形鋼
に適応した場合は、その特異な形状からウェブ、フラン
ジ、フィレットの各部位で、圧延仕上げ温度、圧下率、
冷却速度に差を生じるため、各部位によりベイナイト組
織割合が大きく変化する。その結果として常温・高温強
度、延性、靭性がバラツキ、規準に満たない部位が生じ
る。加えて、これらの元素の添加により溶接部を著しく
硬化させ、靭性を低下させる。The present invention will be described in detail below. The high-temperature strength of steel materials is almost the same as the strengthening mechanism at room temperature below 700 ° C, which is almost half the melting point of iron, and the ferrite grain size is refined, solid solution strengthened by alloying elements, and dispersion strengthened by the hardened phase. It is dominated by precipitation strengthening by fine precipitates. Generally, the increase in high temperature strength is achieved by increasing precipitation resistance by adding Mo and Cr and increasing softening resistance at high temperature by suppressing disappearance of dislocations. But M
Addition of o and Cr significantly enhances the hardenability and changes the ferrite + pearlite structure of the base material into a bainite structure. When a component steel that easily forms a bainite structure is applied to a rolled H-section steel, the rolling finish temperature, the reduction ratio,
Because of the difference in cooling rate, the bainite structure ratio changes greatly depending on each part. As a result, the room temperature / high temperature strength, ductility, and toughness vary, and some parts do not meet the standard. In addition, the addition of these elements significantly hardens the weld and reduces toughness.
【００１５】本発明の特徴は、製鋼工程において、脱酸
の制御、鋳込み後の冷却速度を規制し、鋳片内に多数の
微細なＭｇ系酸化物を晶出・分散させた鋳片により、圧
延加熱時のγ粒径を細粒化した状態から圧延し耐火性・
靭性に優れたＨ形鋼を得ることである。加えて本発明で
は、熱間圧延工程において、熱間圧延パス間でフランジ
表面を水冷し、その復熱時に圧延することを繰り返すこ
とによりフランジの板厚中心部に圧下浸透効果を付与
し、この部位においてもＴＭＣＰによる組織微細化効果
を高め、この組織微細化によりＨ形鋼の各部位における
母材の機械特性を向上するとともに均一化を達成するも
のである。A feature of the present invention is that, in the steelmaking process, the deoxidation is controlled, the cooling rate after pouring is regulated, and a slab in which many fine Mg-based oxides are crystallized and dispersed in the slab, When the rolling is heated, the γ grain size is rolled from a finer state and then fire resistance
It is to obtain an H-section steel excellent in toughness. In addition, in the present invention, in the hot rolling step, the flange surface is water-cooled between the hot rolling passes, and a rolling infiltration effect is imparted to the central portion of the flange thickness by repeating rolling at the time of recuperation, The microstructure refinement effect of TMCP is also enhanced in the parts, and by this microstructure refinement, the mechanical properties of the base material in each part of the H-section steel are improved and the homogenization is achieved.
【００１６】以下に本発明形鋼の成分範囲と制御条件の
限定理由について述べる。まず、Ｃは鋼を強化するため
に添加するもので、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% を超える過剰の添加
は、母材靭性、耐溶接割れ性、溶接熱影響部（以下ＨＡ
Ｚと略記）靭性などを著しく低下させるので、下限を0.
04% 、上限を0.20% とした。The reasons for limiting the composition range and control conditions of the shaped steel of the present invention will be described below. First, C is added to strengthen the steel. If it is less than 0.04%, the strength required for structural steel cannot be obtained. In addition, if added in excess of 0.20%, the base metal toughness, weld crack resistance, and weld heat affected zone (hereinafter HA
(It is abbreviated as Z) It significantly reduces the toughness, etc., so the lower limit is 0.
04% and the upper limit was 0.20%.
【００１７】次に、Ｓｉは母材の強度確保、溶鋼の予備
脱酸などに必要であるが、0.50% を超えるとＨＡＺ組織
内に硬化組織の高炭素島状マルテンサイトを生成し、溶
接継手部靭性を著しく低下させる。また、0.05% 未満で
は必要な溶鋼の予備脱酸ができないためＳｉ含有量を0.
05〜0.50% の範囲に限定した。Ｍｎは母材の強度、靭性
の確保には0.4%以上の添加が必要であるが、溶接部の靭
性、割れ性などの許容できる範囲で上限を1.8%とした。Next, Si is necessary for securing the strength of the base metal and preliminary deoxidation of molten steel. If it exceeds 0.50%, high carbon island martensite with a hardened structure is formed in the HAZ structure, and a welded joint is formed. Remarkably reduces the toughness of the part. If the content is less than 0.05%, the required pre-deoxidation of molten steel cannot be performed, so the Si content is set to 0.
It was limited to the range of 05 to 0.50%. Although Mn needs to be added in an amount of 0.4% or more to secure the strength and toughness of the base metal, the upper limit was set to 1.8% within the allowable range of the toughness and crackability of the welded portion.
【００１８】Ｍｏは母材強度および高温強度の確保に有
効な元素である。0.4%未満ではＭｏ炭化物（Ｍｏ2 Ｃ）
の析出が不十分で強化作用を持たないため十分な高温強
度が確保できず、1.0%超では焼き入れ性が上昇しすぎ母
材及びＨＡＺの靭性が劣化するため0.4 〜1.0%に制限し
た。Ｎは窒化物を生成し、析出強化および粒径の制御作
用を有するが、固溶Ｎはフェライトを強化し、またベイ
ナイト相のラス境界に高炭素島状マルテンサイトを形成
させ靭性を劣化させるためＮ含有量0.004%以下に制限し
た。Mo is an element effective for securing the strength of the base material and the high temperature strength. If less than 0.4%, Mo carbide (Mo 2 C)
Since the precipitation of Al is insufficient and does not have a strengthening effect, sufficient high temperature strength cannot be ensured. If it exceeds 1.0%, the hardenability is excessively increased and the toughness of the base metal and HAZ deteriorates, so the content was limited to 0.4 to 1.0%. N produces nitrides and has precipitation strengthening and grain size control functions, but solute N strengthens ferrite and forms high carbon island martensite at the lath boundary of the bainite phase to deteriorate toughness. The N content was limited to 0.004% or less.
【００１９】Ａｌを0.004%以下としたのは、Ａｌは強力
な脱酸元素であり、0.004%超の含有ではＡｌ含有量の多
い粒子径の大きなＡｌー Ｍｇ系複合酸化物を生成し、微
細な３μｍ以下のＭｇ系酸化物が形成されず、高温再加
熱時においてのγ細粒化ができないためＡｌを0.004%以
下とした。成分を調整した溶鋼を予備脱酸処理を行い溶
存酸素を重量％で0.003 〜0.015%に調整するのは、溶鋼
の高清浄化と同時に鋳片内に微細なＭｇ系酸化物を晶出
させるために行うものである。予備脱酸後の[O] 濃度が
0.003%未満では微細な酸化物が減少し、細粒化できず靭
性を向上できない。一方、0.015%を超える場合は、他の
条件を満たしていても、酸化物が３μｍ以上の大きさに
粗大化し脆性破壊の起点となり、靭性を低下させるため
に予備脱酸後の[O] 濃度を重量％で0.003 〜0.015%に限
定した。Al is set to 0.004% or less because Al is a strong deoxidizing element, and if the content exceeds 0.004%, an Al-Mg-based complex oxide having a large Al content and a large particle size is produced, and it is Since a Mg-based oxide of 3 μm or less is not formed and γ-fine grains cannot be obtained at the time of reheating at high temperature, Al is set to 0.004% or less. Pre-deoxidation treatment of molten steel with adjusted components to adjust the dissolved oxygen to 0.003 to 0.015% by weight is to clean the molten steel highly and at the same time to crystallize fine Mg-based oxide in the slab. It is something to do. [O] concentration after preliminary deoxidation
If it is less than 0.003%, the amount of fine oxides decreases, and it is not possible to make fine particles and improve the toughness. On the other hand, if it exceeds 0.015%, even if the other conditions are satisfied, the oxide coarsens to a size of 3 μm or more and becomes the starting point of brittle fracture, and to reduce toughness, [O] concentration after preliminary deoxidation is increased. Was limited to 0.003 to 0.015% by weight.
【００２０】予備脱酸処理は真空脱ガス、Ａｌ、Ｓｉ、
Ｍｇ脱酸により行った。その理由は真空脱ガス処理は直
接溶鋼中の酸素をガスおよびＣＯガスとして除去し、Ａ
ｌ、Ｓｉ、Ｍｇなどの強脱酸により生成する酸化物系介
在物は浮上、除去しやすく溶鋼の清浄化に有効なためで
ある。次に上述の溶鋼にMg合金を添加し重量％でMg:0.0
01〜0.005%に成分調整した溶鋼を後述する一定の鋳造冷
却速度で鋳込む。The preliminary deoxidizing treatment is performed by vacuum degassing, Al, Si,
It was performed by Mg deoxidation. The reason is that the vacuum degassing process directly removes oxygen in molten steel as gas and CO gas,
This is because oxide-based inclusions such as l, Si, and Mg produced by strong deoxidization are easy to float and remove, and are effective for cleaning molten steel. Next, Mg alloy was added to the above-mentioned molten steel and Mg: 0.0
Molten steel whose composition has been adjusted to 01 to 0.005% is cast at a constant casting cooling rate described later.
【００２１】Ｍｇ添加に使用したMg合金はSi-Mg 及びNi
-Mg である。Ｍｇ合金を用いた理由は合金化によりＭｇ
の濃度を低くし、Ｍｇ酸化物生成時の反応を抑え、添加
時の安全性確保とＭｇの歩留を上げるためである。Ｍｇ
を0.001 〜0.005%に限定するのは、Ｍｇも強力な脱酸元
素であり、晶出したＭｇ酸化物は溶鋼中で容易に浮上分
離されるため0.005%を超えての添加では歩留が低いため
その上限を0.005%とした。また、0.001%未満では目的の
Ｍｇ系酸化物の分散密度が不足するため下限を0.001%と
した。なお、ここでのＭｇ系酸化物は、主にＭｇＯを表
しているが、この酸化物は微量のＡｌおよび不純物とし
て含まれているＣａなどの酸化物と複合化している場合
が多いのでこのような表現を用いた。The Mg alloy used for adding Mg is Si-Mg and Ni.
-Mg. The reason for using Mg alloy is that Mg
This is because the concentration of is reduced, the reaction at the time of forming Mg oxide is suppressed, the safety at the time of addition is secured, and the yield of Mg is increased. Mg
Is limited to 0.001 to 0.005%, Mg is also a strong deoxidizing element, and the crystallized Mg oxide is easily floated and separated in molten steel, so the yield is low if added over 0.005%. Therefore, the upper limit was set to 0.005%. If it is less than 0.001%, the dispersion density of the target Mg-based oxide is insufficient, so the lower limit was made 0.001%. Note that the Mg-based oxide here mainly represents MgO, but since this oxide is often complexed with a trace amount of Al and an oxide such as Ca contained as an impurity, I used the expression.
【００２２】不可避不純物として含有するＰ、Ｓはその
量について特に限定しないが凝固偏析による溶接割れ、
靭性の低下を生じるので、極力低減すべきであり、望ま
しくはＰ、Ｓ量はそれぞれ0.02% 未満である。以上の成
分に加えて、母材強度の上昇、および母材の靭性向上の
目的で、Ｃｒ、Ｃｕ、Ｎｉ、Ｎｂ、Ｖ、Ｔｉの１種また
は２種以上を含有することができる。The amounts of P and S contained as unavoidable impurities are not particularly limited, but welding cracks due to solidification segregation,
Since the toughness is reduced, it should be reduced as much as possible, and the P and S contents are preferably less than 0.02%, respectively. In addition to the above components, one or more of Cr, Cu, Ni, Nb, V, and Ti may be contained for the purpose of increasing the strength of the base material and improving the toughness of the base material.
【００２３】Ｃｒは焼き入れ性の向上により、母材の強
化に有効である。しかし1.0%を超える過剰の添加は、靭
性および硬化性の観点から有害となるため、上限を1.0%
とした。Ｃｕは母材の強化、耐候性に有効な元素である
が、応力除去焼鈍による焼き戻し脆性、溶接割れ性、熱
間加工割れを促進するため、上限を1.0%とした。[0023] Cr is effective in strengthening the base material by improving the hardenability. However, excessive addition exceeding 1.0% is harmful from the viewpoint of toughness and curability, so the upper limit is 1.0%.
And Cu is an element effective for strengthening and weather resistance of the base material, but in order to promote temper embrittlement due to stress relief annealing, weld crackability, and hot work cracking, the upper limit was made 1.0%.
【００２４】Ｎｉは、母材の強靭性を高める極めて有効
な元素であるが2.0%を超える添加は合金コストを増加さ
せ経済的でないので上限を2.0%とした。Ｎｂ、Ｖ、Ｔｉ
は微量添加により圧延組織を微細化でき、それらの炭窒
化物の析出により強化す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:0.04% 、V:0.1%、Ti:0.0
25% とした。Ni is an extremely effective element for enhancing the toughness of the base material, but the addition of more than 2.0% increases the alloy cost and is not economical, so the upper limit was made 2.0%. Nb, V, Ti
Can refine the rolling structure by adding a trace amount, and strengthens by precipitating carbonitrides thereof, so that a low alloy can be obtained and welding characteristics can be improved. However, excessive addition of these elements leads to hardening of the weld and higher yield point of the base metal, so the upper limits of the respective contents are Nb: 0.04%, V: 0.1%, Ti: 0.0
It was set to 25%.
【００２５】成分調整を終了した溶鋼を鋳込む際の冷却
速度は、Ｍｇ系酸化物粒子の個数の増加とその大きさを
制御するため、鋳込み開始から900 ℃までの冷却速度を
0.5〜20℃/sで冷却するのが望ましい。すなわち、過冷
却により晶出する複合酸化物の核生成数を増加させると
同時に冷却中の粒子成長を抑制し、大きさ３μｍ以下に
した酸化物を鋳片に５０個／ｍｍ2 以上含有させるため
に行うものである。この温度間の冷却速度が０．５℃／
ｓ未満の緩冷却では複合酸化物は凝集粗大化し、５０個
／ｍｍ2 未満となり靭性、延性を低下させ、一方、冷却
速度の上限は現状の鋳造技術での冷却速度の限界である
２０℃／ｓとする。The cooling rate at the time of pouring the molten steel whose composition has been adjusted is controlled by the cooling rate from the start of casting to 900 ° C. in order to control the increase in the number of Mg-based oxide particles and their size.
It is desirable to cool at 0.5 to 20 ° C / s. That is, to suppress the grain growth during the same time increasing the number of nuclei generating the composite oxide crystallized cooled by supercooling, for inclusion 50 / mm 2 or more oxides below size 3μm cast slab Is what you do. The cooling rate between these temperatures is 0.5 ° C /
With slow cooling of less than s, the complex oxide aggregates and coarsens to less than 50 pieces / mm 2 and reduces toughness and ductility. On the other hand, the upper limit of the cooling rate is 20 ° C / Let s.
【００２６】次に、鋳片に複合酸化物が５０個／ｍｍ2
以上含む必要がある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の１つを制御するこ
とにあり、鋳片中に高温でのγ粒成長の抑制機能を発揮
する微細なＭｇ系酸化物を分散晶出させることにある。
この粒子の分散個数が５０個／ｍｍ2 未満では、１２０
０〜１３００℃加熱におけるγ粒径がＡＳＴＭ Ｎｏ.
６番以上の細粒をえることはできないため下限を５０個
／ｍｍ2とした。Next, 50 pieces / mm 2 of complex oxides are added to the cast piece.
The reason why the above needs to be included is described. The material properties of the product are controlled by steelmaking, solidification structure of cast slab which is an innate factor governed by the casting process, component segregation, fine composite oxide of the present invention, precipitation and rolling, TMCP, heat treatment process, etc. It is determined by the microstructure of specific factors. Naturally, the property of the slab, which is an innate factor, is inherited in the subsequent process. The feature of the present invention is to control one of the innate factors of the cast slab, and disperse and crystallize a fine Mg-based oxide exhibiting a function of suppressing γ grain growth at high temperature in the cast slab. Especially.
When the number of dispersed particles is less than 50 particles / mm 2, it is 120
Γ particle size at 0 to 1300 ° C heating is ASTM No.
Since it is not possible to obtain fine particles of No. 6 and above, the lower limit was set to 50 / mm 2 .
【００２７】なお、Ｍｇ系酸化物個数は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。
上記の処理を経た鋳片は次に１２００〜１３００℃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１２００℃以上の加熱が必要であり、且つＶ、
Ｎｂなどの元素を十分に固溶させる必要があるため再加
熱温度の下限を１２００℃とした。その上限は加熱炉の
性能、経済性から１３００℃とした。The number of Mg-based oxides is determined by measuring with an X-ray microanalyzer (EPMA).
The slab that has undergone the above treatment is then reheated to a temperature range of 1200 to 1300 ° C. The reason for limiting the reheating temperature to this temperature range is that in the production of shaped steel by hot working, heating at 1200 ° C. or higher is required to facilitate plastic deformation, and V,
The lower limit of the reheating temperature was set to 1200 ° C. because it is necessary to sufficiently dissolve Nb and other elements in solid solution. The upper limit was set to 1300 ° C. in view of the performance and economical efficiency of the heating furnace.
【００２８】熱間圧延のパス間で水冷し、圧延中に一回
以上、フランジ表面温度を７００℃以下に冷却し、以降
の圧延パス間の復熱過程で圧延する水冷・圧延工程を１
回以上繰り返し行うとしたのは、圧延パス間の水冷によ
り、フランジの表層部と内部とに温度差を付け、軽圧下
条件においても内部への加工を浸透させるためと、低温
圧延を短時間で効率的に行うためである．フランジ表面
温度を７００℃以下に冷却した後、復熱過程で圧延する
のは、仕上げ圧延後の加速冷却による表面の焼入れ硬化
を抑制し軟化させるために行うものである。その理由は
フランジ表面温度を７００℃以下に冷却すれば一旦γ／
α変態温度を切り、次の圧延までに表層部は復熱昇温
し、圧延はγ／αの二相共存温度域での加工となり、γ
細粒化と加工された微細αとの混合組織を形成する。こ
れにより表層部の焼き入性を著しく低減でき、加速冷却
により生じる表面層の硬化を防止できるからである。A water-cooling / rolling process in which water is cooled between hot rolling passes, the surface temperature of the flange is cooled to 700 ° C. or lower during rolling once or more, and rolling is performed in the subsequent reheating process between rolling passes is performed.
The reason why it is repeated more than once is that water cooling between rolling passes creates a temperature difference between the surface layer and the inside of the flange, allowing the internal processing to permeate even under light reduction conditions, and low temperature rolling in a short time. This is to do it efficiently. After the flange surface temperature is cooled to 700 ° C. or lower, rolling in the recuperating process is performed in order to suppress quench-hardening and soften the surface due to accelerated cooling after finish rolling. The reason is that once the flange surface temperature is cooled to 700 ° C or lower, γ /
The α-transformation temperature is cut off, the surface layer temperature is reheated by the next rolling, and rolling is performed in the two-phase coexisting temperature range of γ / α.
A mixed structure of fine grain and processed fine α is formed. This is because the hardenability of the surface layer portion can be remarkably reduced and the hardening of the surface layer caused by accelerated cooling can be prevented.
【００２９】また、圧延終了後、引続き、０．５〜１０
℃／Ｓの冷却速度で７００〜４００℃まで冷却し放冷す
るとしたのは、加速冷却によりフェライトの粒成長抑制
とベイナイト組織を微細化し高強度・高靭性を得るため
である。引き続く加速冷却を７００〜４００℃で停止す
るのは、７００℃を超える温度で加速冷却を停止する
と、一部がAr1 点以上となりγ相を残存し、このγ相
が、共存するフェライトを核にフェライト変態し、さら
にフェライトが成長し粗粒化するために加速冷却の停止
温度を７００℃以下とした。また、４００℃未満の冷却
では、その後の放冷中にベイナイト相のラス間に生成す
る高炭素マルテンサイトが、冷却中にセメンタイトを析
出することにより分解できず、硬化相として存在するこ
とになる。これが脆性破壊の起点として作用し、靭性の
低下を招くために、この温度範囲に限定した。After rolling is completed, 0.5-10
The reason for cooling to 700 to 400 ° C at a cooling rate of ° C / S and allowing to cool is to suppress grain growth of ferrite and refine the bainite structure by accelerated cooling to obtain high strength and high toughness. The reason for stopping the subsequent accelerated cooling at 700 to 400 ° C. is that if the accelerated cooling is stopped at a temperature higher than 700 ° C., a part becomes Ar 1 point or more and the γ phase remains, and this γ phase forms a core of coexisting ferrite. The temperature at which accelerated cooling was stopped was set to 700 ° C. or less in order to transform into ferrite and to further grow ferrite to coarsen grains. Further, in the case of cooling below 400 ° C., the high carbon martensite formed between the laths of the bainite phase during the subsequent cooling cannot be decomposed by precipitating cementite during the cooling and exists as a hardening phase. . This acts as a starting point for brittle fracture and causes a decrease in toughness, so the temperature range is limited to this range.
【００３０】[0030]
【実施例】試作形鋼は転炉溶製し、合金を添加後、予備
脱酸処理を行い、溶鋼の酸素濃度を調整後、Mg合金を添
加し、連続鋳造により250 〜300mm 厚鋳片に鋳造した。
鋳片の冷却はモールド下方の二次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。該鋳片を加熱し、
粗圧延工程の図示は省略するが、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。圧延パス間水冷は
中間ユニバーサル圧延機４の前後に水冷装置５ａを設
け、フランジ外側面のスプレー冷却とリバース圧延の繰
り返しにより行い、圧延後の加速冷却は仕上げユニバー
サル圧延機６で圧延終了後にその後面に設置した冷却装
置５ｂでフランジ外側面をスプレー冷却した。Example: Prototype shaped steel was melted in a converter, added with alloy and then subjected to preliminary deoxidation treatment, and after adjusting the oxygen concentration of the molten steel, Mg alloy was added and continuously cast into 250 to 300 mm thick slabs. Cast.
The cooling of the slab was controlled by selecting the amount of water in the secondary cooling zone below the mold and the drawing speed of the slab. Heating the slab,
Although illustration of the rough rolling step is omitted, H-section steel was rolled by the universal rolling apparatus train shown in FIG. Water cooling between rolling passes is performed by providing water cooling devices 5a before and after the intermediate universal rolling mill 4 and repeating spray cooling and reverse rolling on the outer surface of the flange. The outer side surface of the flange was spray-cooled by the cooling device 5b installed in.
【００３１】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、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部はＨ形
鋼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、これらの２箇所によりＨ形鋼の
機械試験特性を代表できると判断したためである。The mechanical characteristics are shown in FIG. 2, which is 1/4, 1 / of the total flange width (B) at the center (1 / 2t 2 ) of the plate thickness t 2 of the flange 2.
Test pieces were collected from 2 widths (1 / 4B, 1 / 2B) and determined. In addition,
The characteristics at these points were obtained because the flange 1 / 4F shows the average mechanical characteristics of the H-section steel and the flange 1 / 2F section shows the lowest deterioration of the characteristics. This is because it was determined that the above-mentioned mechanical test characteristics can be represented.
【００３２】表１、表３には、本発明鋼及び比較鋼の化
学成分値を、表２、表４には、それらの鋼の鋳込み後の
冷却速度及び鋳片中のＭｇ系酸化物の分散密度を示す。
表５、表６および表７には、圧延加熱時のγ粒度、圧延
・加速冷却条件及び製品の機械試験特性値を示す。な
お、圧延加熱温度を１３００℃に揃えたのは、一般的に
加熱温度の低下はγ粒を細粒化し機械特性を向上させる
ことは周知であり、高温加熱条件で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機
械試験特性を代表できると判断したためである。Tables 1 and 3 show the chemical composition values of the steels of the present invention and comparative steels, and Tables 2 and 4 show the cooling rates after casting of these steels and the Mg-based oxides in the cast pieces. The dispersion density is shown.
Tables 5, 6, and 7 show the γ grain size during rolling heating, rolling / accelerated cooling conditions, and mechanical test characteristic values of products. It is well known that the rolling heating temperature is set to 1300 ° C. Generally, it is well known that the lowering of the heating temperature makes the γ grains finer to improve the mechanical properties, and shows the minimum value of the mechanical properties under the high temperature heating conditions. This is because it was determined that this value can represent the mechanical test characteristics at heating temperatures lower than that.
【００３３】[0033]
【表１】 [Table 1]
【００３４】[0034]
【表２】 [Table 2]
【００３５】[0035]
【表３】 [Table 3]
【００３６】[0036]
【表４】 [Table 4]
【００３７】[0037]
【表５】 [Table 5]
【００３８】[0038]
【表６】 [Table 6]
【００３９】[0039]
【表７】 [Table 7]
【００４０】表５、６および７に示すように、本発明に
よるＨ形鋼１〜５、Ａ１〜Ａ３は目標の常温の降伏点範
囲がＪＩＳ規格の下限値＋120N/mm2以内のSM490 ではYP
=325〜445N/mm2、SM520 ではYP=355〜475N/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）及び６００℃
での降伏強度と常温の降伏強度の比が２／３以上であ
り、−１０℃でのシャルピー衝撃値４７(J) 以上を十分
に満たしている。一方、比較鋼のＨ形鋼６では、成分の
ＮとＡｌが本発明の上限値を超えたため、過剰のＮはフ
ェライトの靭性を低下し、過剰のＡｌはＭｇ系酸化物の
生成を阻害し、この分散個数で５０個／ｍｍ2 未満とな
り、γ粒度がＡＳＴＭ Ｎｏ．６番以下と粗粒化し微細
組織が得られない。これのためシャルピー衝撃値が開発
目標の−１０℃で４７Ｊ以上を達成できない。比較鋼の
Ｈ形鋼７では、Ｍｇ添加前の溶鋼の酸素濃度が本発明の
下限値以下となっているためにＭｇ系酸化物の個数が不
足し、それに反し、比較鋼のＨ形鋼８では、この酸素濃
度の上限値を超えているために３μｍ以上の大きさの粗
大な酸化物が形成されるために、何れもシャルピー衝撃
値が開発目標の−１０℃で４７Ｊ以上を達成できない。
比較鋼のＨ形鋼９では、Ｍｇが添加されていない。次い
で、比較鋼のＨ形鋼１０では、成分・製鋼条件は満たし
ているものの圧延中でのフランジ外側面を７００℃以下
に水冷する処理が施されていないので、水冷停止温度が
７１０℃と水冷停止温度の制限の上限を超え、圧延後の
冷却速度が１／２Ｆ部では冷却速度の制限以下となるた
め常温強度及び６００℃での強度不足をきたす。As shown in Tables 5, 6 and 7, the H-section steels 1 to 5 and A1 to A3 according to the present invention are YP for SM490 whose target yield point range at room temperature is within the JIS standard lower limit value + 120 N / mm 2.
= 325 to 445 N / mm 2 , and SM520 YP = 355 to 475 N / mm 2 , and the yield ratio (YP / TS) satisfies the low YR value of 0.8 or less, tensile strength (JISG3106) and 600 ° C.
The ratio of the yield strength at room temperature to the yield strength at room temperature is 2/3 or more, and the Charpy impact value at -10 ° C of 47 (J) or more is sufficiently satisfied. On the other hand, in the H-section steel 6 of the comparative steel, the components N and Al exceeded the upper limits of the present invention, so excess N reduces the toughness of the ferrite, and excess Al hinders the formation of Mg-based oxides. , The number of dispersed particles is less than 50 / mm 2 , and the γ particle size is ASTM No. No. 6 or less is coarse grained and a fine structure cannot be obtained. For this reason, the Charpy impact value cannot reach 47 J or more at the development target of -10 ° C. In the H-section steel 7 of the comparative steel, the oxygen concentration of the molten steel before the addition of Mg was below the lower limit value of the present invention, and therefore the number of Mg-based oxides was insufficient. Then, since the coarse oxide having a size of 3 μm or more is formed because the upper limit of the oxygen concentration is exceeded, the Charpy impact value cannot reach 47 J or more at the development target of −10 ° C. in any case.
In the H-section steel 9 of the comparative steel, Mg is not added. Next, in the H-section steel 10 of the comparative steel, although the composition and the steelmaking conditions are satisfied, the outer surface of the flange during rolling is not water-cooled to 700 ° C or less, so that the water-cooling stop temperature is 710 ° C. If the cooling rate after rolling exceeds the upper limit of the limit of the stop temperature and the cooling rate after rolling is equal to or less than the limit of the cooling rate in the 1/2 F part, the room temperature strength and the strength at 600 ° C. are insufficient.
【００４１】規格強度、５２０ＭＰａ級鋼に区分される
比較鋼のＨ形鋼Ａ４では、Ｍｏ含有量が本発明の下限値
を以下であるため６００℃での強度不足となり、加えて
Ｍｇが添加されていないので組織の微細化ができずシャ
ルピー衝撃値が開発目標の−１０℃で４７Ｊ以上を達成
できない。また、比較鋼のＨ形鋼Ａ５では、鋳込み後の
冷却速度が下限値以下であるのでＭｇ系酸化物の個数が
不足し、シャルピー衝撃値がクリアーできない。In the H-section steel A4, which is a comparative steel classified into the standard strength and the 520 MPa class steel, the Mo content is below the lower limit value of the present invention, so the strength at 600 ° C. becomes insufficient, and in addition Mg is added. Since the structure is not refined, the Charpy impact value cannot reach 47 J or more at the development target of -10 ° C. Further, in the H-section steel A5 of the comparative steel, the cooling rate after casting is not more than the lower limit value, and therefore the number of Mg-based oxides is insufficient, and the Charpy impact value cannot be cleared.
【００４２】即ち、本発明の製造法の要件が総て満たさ
れた時に、表５、６および７に示されるＨ形鋼１〜５、
Ａ１〜Ａ３のように、圧延形鋼の機械試験特性の最も保
証しにくいフランジ板厚1/2,幅1/2 部においても十分な
常温・高温強度、低温靭性を有する、耐火性及び靭性の
優れた圧延形鋼の生産が可能になる。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
を有する他の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 manufacturing method of the present invention are satisfied, H-section steels 1 to 5 shown in Tables 5, 6 and 7,
Like A1 to A3, it is hard to guarantee the mechanical test characteristics of rolled steel, and it has sufficient room temperature / high temperature strength and low temperature toughness even in the flange plate thickness 1/2 and width 1/2 part. It enables the production of excellent rolled steel. The rolled shaped steel targeted by the present invention is not limited to the H-shaped steel of the above-mentioned embodiment, but may be other shaped steels having a flange such as I-shaped steel, chevron steel, channel steel, and unequal-thickness chevron steel. Of course, it is also applicable.
【００４３】[0043]
【発明の効果】本発明による圧延形鋼は機械試験特性の
最も保証しにくいフランジ板厚1/2,幅1/2 部においても
十分な強度、靭性を有し、高温特性に優れ、耐火材の被
覆厚さが従来の２０〜５０％で耐火目的を達成できる、
優れた耐火性及び靭性を持つ形鋼が圧延ままで製造可能
になり、施工コスト低減、工期の短縮による大幅なコス
ト削減が図られ、大型建造物の信頼性向上、安全性の確
保、経済性等の産業上の効果は極めて顕著なものがあ
る。EFFECTS OF THE INVENTION The rolled steel according to the present invention has sufficient strength and toughness even in the flange plate thickness 1/2 and width 1/2 part where the mechanical test characteristics are the most difficult to guarantee, and has excellent high temperature characteristics and is a refractory material. The coating thickness of 20 to 50% of the conventional one can achieve the fireproof purpose,
Shaped steel with excellent fire resistance and toughness can be manufactured as it is rolled, and construction cost can be reduced, construction cost can be reduced significantly, and reliability of large buildings can be improved. Industrial effects such as are extremely remarkable.
【図面の簡単な説明】[Brief description of 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 diagram of an example of device arrangement for carrying out 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 view showing a cross-sectional shape of 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 for front and rear surfaces of intermediate rolling mill 5b ... Finishing mill Rear surface cooling device 6 ... Finishing rolling mill
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｃ２２Ｃ 38/58 Ｃ２２Ｃ 38/58 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI Technical indication C22C 38/58 C22C 38/58
Claims (4)
予備脱酸処理によって、溶存酸素を重量％で0.003 〜0.
015%に調整後、Mg合金を添加し重量％でMg:0.001〜0.00
5%に成分調整した溶鋼を鋳込んだ鋳片内に大きさ３μｍ
以下のMg系酸化物を50個/mm2以上含有する鋳片を熱間圧
延して製造したことを特徴とする耐火用圧延形鋼。1. By weight%, C: 0.04 to 0.20%, Si: 0.05 to 0.50%, Mn: 0.4 to 1.8%, Mo: 0.4 to 1.0%, N: 0.004% or less, Al: 0.004% or less, , Molten steel whose balance consists of Fe and unavoidable impurities,
By pre-deoxidation treatment, the dissolved oxygen content is 0.003 to 0.
After adjusting to 015%, Mg alloy is added and Mg in weight% is 0.001-0.00
3 μm in size in a slab containing molten steel adjusted to 5% composition
A fire-resistant rolled shaped steel produced by hot rolling a slab containing the following 50 or more Mg-based oxides / mm 2 .
以下、Nb：0.04% 以下、V:0.1%以下、Ti:0.025% 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を、予備脱酸処理によって、
溶存酸素を重量％で0.003 〜0.015%に調整後、Mg合金を
添加し重量％でMg:0.001〜0.005%に成分調整した該溶鋼
を鋳込んだ鋳片内に大きさ３μｍ以下のMg系酸化物を50
個/mm2以上含有する鋳片を熱間圧延して製造したことを
特徴とする耐火用圧延形鋼。2. By weight%, C: 0.04 to 0.20%, Si: 0.05 to 0.50%, Mn: 0.4 to 1.8%, Mo: 0.4 to 1.0%, N: 0.004% or less, Al: 0.004% or less, In addition, Cr: 1.0% or less, Cu: 1.0% or less, Ni: 2.0%
A molten steel containing one or more of Nb: 0.04% or less, V: 0.1% or less, and Ti: 0.025% or less, and the balance consisting of Fe and unavoidable impurities, is preliminarily deoxidized.
After adjusting the dissolved oxygen to 0.003 to 0.015% by weight, the Mg alloy was added and the composition was adjusted to Mg: 0.001 to 0.005% by weight%. 50 things
A fire-resistant rolled shaped steel produced by hot rolling a slab containing at least 1 piece / mm 2 .
予備脱酸処理によって、溶存酸素を重量％で0.003 〜0.
015%に調整後、Mg合金を添加し重量％でMg:0.001〜0.00
5%に成分調整した溶鋼を鋳込んだ鋳片を1200〜1300℃の
温度域に再加熱後に圧延を開始し、圧延工程で形鋼のフ
ランジ表面温度を700 ℃以下に水冷し、以降の圧延パス
間の復熱過程で圧延する水冷・圧延工程を一回以上繰り
返し圧延し、圧延終了後に0.5 〜10℃/sの冷却速度で70
0 〜400 ℃まで冷却し放冷することを特徴とする耐火用
圧延形鋼の製造方法。3. By weight%, C: 0.04 to 0.20%, Si: 0.05 to 0.50%, Mn: 0.4 to 1.8%, Mo: 0.4 to 1.0%, N: 0.004% or less, Al: 0.004% or less, , Molten steel whose balance consists of Fe and unavoidable impurities,
By pre-deoxidation treatment, the dissolved oxygen content is 0.003 to 0.
After adjusting to 015%, Mg alloy is added and Mg in weight% is 0.001-0.00
A slab containing molten steel adjusted to a composition of 5% is reheated to a temperature range of 1200 to 1300 ° C, and then rolling is started.The flange surface temperature of the shaped steel is water-cooled to 700 ° C or less in the rolling process, and subsequent rolling is performed. The water-cooling / rolling process, which involves rolling in the heat recovery process between passes, is repeated one or more times, and after completion of rolling, the cooling rate is 0.5-10 ° C / s.
A method for producing a rolled shaped steel for refractory, which comprises cooling to 0 to 400 ° C and allowing to cool.
以下、Nb：0.04% 以下、V:0.1%以下、Ti:0.025% 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を、予備脱酸処理によって、
溶存酸素を重量％で0.003 〜0.015%に調整後、Mg合金を
添加し重量％でMg:0.001〜0.005%に成分調整した該溶鋼
を鋳込んだ鋳片を1200〜1300℃の温度域に再加熱後に圧
延を開始し、圧延工程で形鋼のフランジ表面温度を700
℃以下に水冷し、以降の圧延パス間の復熱過程で圧延す
る水冷・圧延工程を一回以上繰り返し圧延し、圧延終了
後に0.5 〜10℃/sの冷却速度で700 〜400 ℃まで冷却し
放冷することを特徴とする耐火用圧延形鋼の製造方法。4. By weight%, C: 0.04 to 0.20%, Si: 0.05 to 0.50%, Mn: 0.4 to 1.8%, Mo: 0.4 to 1.0%, N: 0.004% or less, Al: 0.004% or less, In addition, Cr: 1.0% or less, Cu: 1.0% or less, Ni: 2.0%
A molten steel containing one or more of Nb: 0.04% or less, V: 0.1% or less, and Ti: 0.025% or less, and the balance consisting of Fe and unavoidable impurities, is preliminarily deoxidized.
After adjusting the dissolved oxygen to 0.003 to 0.015% by weight, Mg alloy was added to adjust the composition of Mg: 0.001 to 0.005% by weight, and the cast slab containing the molten steel was re-heated to the temperature range of 1200 to 1300 ° C. Rolling is started after heating, and the flange surface temperature of the section steel is increased to 700 during the rolling process.
Water-cooling to below ℃ and rolling in the subsequent reheating process between rolling passes is repeated at least once, and after completion of rolling, it is cooled to 700 to 400 ℃ at a cooling rate of 0.5 to 10 ℃ / s. A method for producing a fire-resistant rolled shaped steel, characterized by allowing to cool.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08961795A JP3285732B2 (en) | 1995-04-14 | 1995-04-14 | Rolled section steel for refractory and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP08961795A JP3285732B2 (en) | 1995-04-14 | 1995-04-14 | Rolled section steel for refractory and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08283902A true JPH08283902A (en) | 1996-10-29 |
| JP3285732B2 JP3285732B2 (en) | 2002-05-27 |
Family
ID=13975720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP08961795A Expired - Lifetime JP3285732B2 (en) | 1995-04-14 | 1995-04-14 | Rolled section steel for refractory and method for producing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3285732B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015159793A1 (en) * | 2014-04-15 | 2015-10-22 | 新日鐵住金株式会社 | Steel h-beam and method for manufacturing same |
| CN112501499A (en) * | 2020-10-21 | 2021-03-16 | 南京钢铁股份有限公司 | 100 mm-thick anti-seismic fire-resistant steel plate with yield strength of 460MPa and manufacturing method thereof |
| CN112501500A (en) * | 2020-10-28 | 2021-03-16 | 南京钢铁股份有限公司 | 100mm extra-thick shock-resistant refractory steel with yield strength of 345MPa and preparation method thereof |
| CN115948696A (en) * | 2022-12-20 | 2023-04-11 | 中车齐齐哈尔车辆有限公司 | Cast steel material, coupler knuckle, preparation method of coupler knuckle and railway vehicle |
-
1995
- 1995-04-14 JP JP08961795A patent/JP3285732B2/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2015159793A1 (en) * | 2014-04-15 | 2015-10-22 | 新日鐵住金株式会社 | Steel h-beam and method for manufacturing same |
| JPWO2015159793A1 (en) * | 2014-04-15 | 2017-04-13 | 新日鐵住金株式会社 | H-section steel and its manufacturing method |
| US10280476B2 (en) | 2014-04-15 | 2019-05-07 | Nippon Steel & Sumitomo Metal Corporation | H-section steel and method of producing the same |
| CN112501499A (en) * | 2020-10-21 | 2021-03-16 | 南京钢铁股份有限公司 | 100 mm-thick anti-seismic fire-resistant steel plate with yield strength of 460MPa and manufacturing method thereof |
| CN112501500A (en) * | 2020-10-28 | 2021-03-16 | 南京钢铁股份有限公司 | 100mm extra-thick shock-resistant refractory steel with yield strength of 345MPa and preparation method thereof |
| CN112501500B (en) * | 2020-10-28 | 2022-03-01 | 南京钢铁股份有限公司 | 100mm extra-thick shock-resistant refractory steel with yield strength of 345MPa and preparation method thereof |
| CN115948696A (en) * | 2022-12-20 | 2023-04-11 | 中车齐齐哈尔车辆有限公司 | Cast steel material, coupler knuckle, preparation method of coupler knuckle and railway vehicle |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3285732B2 (en) | 2002-05-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP2760713B2 (en) | Method for producing controlled rolled steel with excellent fire resistance and toughness | |
| JP2661845B2 (en) | Manufacturing method of oxide-containing refractory section steel by controlled rolling | |
| JP2006336105A (en) | Heat-resistant steel product and method for production thereof | |
| JP2007284712A (en) | Method for producing thick high-strength steel plate excellent in toughness and thick high-strength steel plate excellent in toughness | |
| JP3397271B2 (en) | Rolled section steel for refractory and method for producing the same | |
| JPH10147834A (en) | 590mpa class rolled shape steel and its production | |
| JPH04279247A (en) | Manufacture of transgranular ferrite system rolled shapes with excellent fire resistance and toughness | |
| JPH05263182A (en) | Manufacture of low alloy rolled shape steel excellent in toughness | |
| JP3285732B2 (en) | Rolled section steel for refractory and method for producing the same | |
| JP3507259B2 (en) | 590 MPa class rolled section steel and method for producing the same | |
| JP3472017B2 (en) | Refractory rolled steel and method for producing the same | |
| JP3241199B2 (en) | Oxide particle-dispersed slab and method for producing rolled section steel with excellent toughness using the slab | |
| JPH10204572A (en) | 700×c fire resistant rolled shape steel and its production | |
| JP3181448B2 (en) | Oxide-containing dispersed slab and method for producing rolled section steel with excellent toughness using the slab | |
| JP3426425B2 (en) | Slab for refractory rolled section steel and method for producing refractory rolled section steel from the same | |
| JPH04279248A (en) | Manufacture of rolled shapes piersed fine oxide with excellent toughness | |
| JP3285731B2 (en) | Rolled section steel for refractory and method for producing the same | |
| JPH05132716A (en) | Manufacture of rolled shape steel excellent in toughness | |
| JP3107698B2 (en) | Method for producing shaped steel having flange excellent in strength, toughness and fire resistance | |
| JP3241198B2 (en) | Oxide particle-dispersed slab for refractory and method for producing rolled section steel for refractory using this slab | |
| JP3403300B2 (en) | 590 MPa class rolled section steel and method for producing the same | |
| JPH0790473A (en) | Production of oxide-containing slab for fireproofing and rolled shape steel for fireproofing by the same slab | |
| JPH0776725A (en) | Production of shape steel excellent in toughness | |
| JP2543282B2 (en) | Method for producing controlled rolled steel with excellent toughness | |
| JPH0776724A (en) | Production of shape steel excellent in toughness |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20020129 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080308 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090308 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090308 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100308 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110308 Year of fee payment: 9 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120308 Year of fee payment: 10 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130308 Year of fee payment: 11 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130308 Year of fee payment: 11 |
|
| S531 | Written request for registration of change of domicile |
Free format text: JAPANESE INTERMEDIATE CODE: R313531 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130308 Year of fee payment: 11 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130308 Year of fee payment: 11 |
|
| S533 | Written request for registration of change of name |
Free format text: JAPANESE INTERMEDIATE CODE: R313533 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130308 Year of fee payment: 11 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140308 Year of fee payment: 12 |
|
| EXPY | Cancellation because of completion of term |