JPH1096024A - Manufacture of steel product for earthquake-proof building, excellent in fire resistance - Google Patents
Manufacture of steel product for earthquake-proof building, excellent in fire resistanceInfo
- Publication number
- JPH1096024A JPH1096024A JP25022296A JP25022296A JPH1096024A JP H1096024 A JPH1096024 A JP H1096024A JP 25022296 A JP25022296 A JP 25022296A JP 25022296 A JP25022296 A JP 25022296A JP H1096024 A JPH1096024 A JP H1096024A
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- steel
- strain rate
- ferrite
- bainite
- earthquake
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、耐震性を重視して
設計される建築分野、主として活断層近傍の重要構造物
に用いられる耐火性に優れた耐震用建築鋼材の製造方法
に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction field designed with an emphasis on seismic resistance, and more particularly to a method of manufacturing a fire-resistant building steel material excellent in fire resistance used for important structures near an active fault.
【０００２】[0002]
【従来の技術】昭和５６年に改正施行された建築物の耐
震設計法は、鋼材が降伏後、最大強さに達するまでの塑
性域での変形能力を活用して、地震入力エネルギーを吸
収させ、建築物の耐震安全性を確保しようとするもので
それまでの構造体各部に生ずる応力度を鋼材の降伏点以
内に留めるという弾性設計を大幅に変更している。この
ことから、新耐震設計法が適用される建築物の鋼材は、
降伏後の変形性能を表すパラメーターである降伏比（Ｙ
Ｒ）が低いこと、すなわち低降伏比が求められるように
なった。2. Description of the Related Art The seismic design method for buildings, which was revised and enforced in 1981, uses the deformation capability in the plastic region until the steel reaches its maximum strength after yielding to absorb the earthquake input energy. In order to ensure the seismic safety of the building, the elastic design has been drastically changed to keep the stress generated in each part of the structure within the yield point of the steel material up to that point. From this, the steel materials of buildings to which the new seismic design method is applied,
The yield ratio (Y, a parameter representing the deformation performance after yielding
R) is low, that is, a low yield ratio is required.
【０００３】ＴＳ４９０ＭＰａ級の鋼材は、熱間圧延を
再結晶域で仕上げ、組織の粗粒化を図り低降伏比を確保
している。また、ＴＳ５７０ＭＰａ級あるいはそれ以上
の高強度鋼では、フェライト−オーステナイトの２相域
から焼入することで、フェライトとベイナイトあるいは
マルテンサイトの２相組織にすることで低降伏比を確保
している。[0003] The TS490 MPa class steel material is subjected to hot rolling in a recrystallization region, coarsening the structure, and securing a low yield ratio. Further, in a high-strength steel of TS570 MPa class or higher, a low yield ratio is secured by quenching from a two-phase region of ferrite-austenite to form a two-phase structure of ferrite and bainite or martensite.
【０００４】１９９５年１月の阪神大地震では、上記の
耐震設計法で想定していたような震源が遠方にある海洋
型タイプの地震と異なり、震源が非常に近い活断層タイ
プの地震であった。活断層タイプの地震の場合に揺れの
速度が非常に速く、建物に歪速度にして１０-1〜１０／
秒の高速変形が加えられるという特徴がある。現在の建
築鋼材は上述したように低ＹＲであるが、それは通常の
歪速度１０-2／秒前後で引張った時の値であり、上記の
ような高歪速度での変形の場合、低ＹＲを示すか疑問で
あった。本発明者らが従来の圧延まま（フェライト＋パ
ーライト組織）のＳＮ４９０級の鋼について歪速度を変
化させ引張試験を行ったところ、歪速度１０-2／秒前後
の場合にはＹＲ＜８０％であったものが、歪速度１０／
秒前後の場合にはＹＲは大きく上昇し８０％以上の値に
なってしまうことが判明した。[0004] In the Hanshin Earthquake of January 1995, unlike the marine-type earthquake in which the hypocenter was distant as assumed in the above seismic design method, it was an active fault-type earthquake whose epicenter was very close. Was. In the case of an active fault type earthquake, the speed of shaking is very high, and the strain rate of the building is 10 -1 to 10 /
The feature is that high-speed deformation of seconds is added. As described above, the current building steel material has a low YR, which is a value when pulled at a normal strain rate of about 10 -2 / sec. In the case of deformation at a high strain rate as described above, the low YR is used. Was doubtful. The present inventors conducted a tensile test while changing the strain rate of a conventional as-rolled (ferrite + pearlite) SN490 grade steel. When the strain rate was about 10 −2 / sec, YR <80% There was a strain rate of 10 /
It has been found that in the case of about seconds, the YR greatly increases and reaches a value of 80% or more.
【０００５】また、阪神大地震では、構造部材が高速の
繰り返し塑性変形を受け脆化し、次の引張変形を受けた
時に脆性破壊する事例があった。脆性破壊が起こると建
物の大崩壊にもつながりかねないため、耐震用鋼材とし
ては避けなければならない破壊様式である。従来のＳＮ
４９０級の鋼も予歪を受けていない場合には、脆性−延
性破面遷移温度は室温以下と十分な靭性を有している
が、高速の繰り返し予歪が加わった場合には、どの程度
の劣化を示すか不明であった。本発明者らは、従来のＳ
Ｎ４９０級の数種類の鋼に対し、歪速度１０／秒で正負
鋼板の歪漸増型（１％圧縮塑性歪付与→１％引張塑性歪
付与→２％圧縮塑性歪付与→２％引張塑性歪付与→４％
圧縮塑性歪付与→４％引張塑性歪付与、以後この予歪付
加を±１＋２＋４％と記す）の予歪を与えた後、シャル
ピー衝撃試験を実施したところ、脆性−延性破面遷移温
度が室温以上になるものも現れた。In the case of the Great Hanshin Earthquake, there have been cases where structural members are embrittled by repeated high-speed plastic deformation, and brittlely fracture when subjected to the next tensile deformation. If brittle fracture occurs, it may lead to a large collapse of the building, so this is a failure mode that must be avoided as steel for earthquake resistance. Conventional SN
When the 490 grade steel is not subjected to prestrain, the brittle-ductile fracture surface transition temperature has a sufficient toughness of not more than room temperature. It was not clear whether or not it exhibited deterioration. The present inventors have proposed a conventional S
For several types of N490 grade steel, a strain increasing rate of positive and negative steel plates at a strain rate of 10 / sec (1% compressive plastic strain → 1% tensile plastic strain → 2% compressive plastic strain → 2% tensile plastic strain → 4%
After applying a pre-strain of compressive plastic strain → 4% tensile plastic strain, and then applying this pre-strain as ± 1 + 2 + 4%), a Charpy impact test was performed. The brittle-ductile fracture surface transition temperature was higher than room temperature. Also appeared.
【０００６】建築鋼材の従来技術の中には、特開平２−
１９７５２２号公報や特開平５−２１４４０号公報のよ
うに低温靭性に優れた低降伏比鋼に関するものがある。
しかしながら、どちらも通常の歪速度での引張試験しか
実施しておらず、高歪速度でのＹＲ値が示されていな
い。また、靭性も予歪が無い場合でのシャルピー衝撃試
験値であり、予歪が加わった後の靭性値は不明である。
そこで、本発明者らは、上記両提案に沿って鋼を試作
し、これら試作鋼の高歪速度（＝１０／秒）での引張特
性ならびに高歪速度（＝１０／秒）で±１＋２＋４％の
繰り返し予歪を与えた後の靭性について調べた。その結
果、高歪速度（＝１０／秒）での引張試験のＹＲは８０
％を越える値となった。また、高速繰り返し予歪後の靭
性はばらつき、なかには vＥ-5＜２０Ｊを示す著しく脆
化しているものが散見された。すなわち、活断層タイプ
の地震の場合には、十分な耐震性を有していないことが
わかった。[0006] In the prior art of building steel materials, Japanese Patent Laid-Open No.
Japanese Patent Application Laid-Open No. 197522 and Japanese Patent Application Laid-Open No. 5-214040 relate to a low yield ratio steel having excellent low-temperature toughness.
However, in both cases, only a tensile test at a normal strain rate was performed, and the YR value at a high strain rate was not shown. Also, the toughness is a Charpy impact test value when there is no pre-strain, and the toughness after pre-strain is applied is unknown.
Therefore, the present inventors prototyped steels in accordance with the above proposals, and obtained tensile properties of these prototype steels at a high strain rate (= 10 / sec) and ± 1 + 2 + 4% at a high strain rate (= 10 / sec). The toughness after repeated prestraining was examined. As a result, the YR of the tensile test at a high strain rate (= 10 / sec) was 80.
%. In addition, the toughness after high-speed cyclic prestrain varied, and some of them were extremely brittle, showing vE-5 <20 J. In other words, it was found that in the case of an active fault type earthquake, it did not have sufficient earthquake resistance.
【０００７】さらに、建築物の火災に関して、耐火設計
の見直しが行われたことにより、高温強度に優れた耐火
鋼を用いて耐火被覆を減らすことが可能となった。耐火
鋼材の使用は、工期の短縮、工事費の削減、建築物内の
有効面積の拡張を図ることにつながるため、こういった
新しい設計法が盛んになってきている。低降伏比と耐火
性を兼ね備えた建築用鋼材については、特開平４−８３
８２１号公報、特開平４−５６７２３号公報、特開平４
−５６３６２号公報等が提案されている。そこで本発明
者らは、上記両提案に沿って鋼を試作し、これら試作鋼
についても、前述した発明鋼（特開平２−１９７５２２
号公報や特開平５−２１４４０号公報）と同様に、高歪
速度での引張特性を調べた。その結果、高歪速度（＝１
０／秒）での降伏比が８０％以上となってしまうことが
判明した。[0007] Further, with respect to fires in buildings, a review of fire-resistant design has made it possible to reduce fire-resistant coatings by using fire-resistant steel excellent in high-temperature strength. The use of refractory steels has led to shorter construction periods, lower construction costs, and an increase in the effective area of buildings. For construction steel materials having both low yield ratio and fire resistance, see JP-A-4-83.
821, JP-A-4-56723, JP-A-4-56723
Japanese Patent Application No. 56362/1996 has been proposed. Therefore, the present inventors made a trial production of steel in accordance with the above proposals, and these trial production steels are also described in the above-mentioned invention steel (JP-A-2-197522).
In the same manner as in Japanese Unexamined Patent Publication (Kokai) No. Hei. 5-214440, tensile properties at a high strain rate were examined. As a result, a high strain rate (= 1)
(0 / sec) was found to be 80% or more.
【０００８】[0008]
【発明が解決しようとする課題】以上のことから、本発
明が解決しようとする課題は、高歪速度で変形を受ける
場合にも低ＹＲ（≦８０％）を示し、かつ高歪速度で繰
り返し予歪を受けた後も安定して優れた靭性を示し、さ
らに耐火性に優れた、耐火設計と活断層近傍の構造物の
塑性耐震設計を組み合わせた設計法を可能にする耐火性
に優れた耐震鋼材の製造方法を提供するものである。From the above, the problem to be solved by the present invention is to exhibit a low YR (≦ 80%) even when subjected to deformation at a high strain rate, and to repeat at a high strain rate. Stable and excellent toughness even after being subjected to pre-strain, and also excellent in fire resistance.Excellent fire resistance that enables a design method combining fire resistance design and plastic seismic design of structures near active faults. It is intended to provide a method for manufacturing an earthquake-resistant steel material.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、この課題
を解決すべく、ミクロ組織と高歪速度におけるＹＲの関
係を鋭意検討した結果、以下に示す重要な知見を見いだ
した。まず、図１は表２のＡ１〜Ａ３鋼板を供試材に用
いて、引張歪速度と降伏比（＝降伏強度／引張強度）の
関係を示したものであり、図中の“α”はフェライトの
略称“Ｂ”はベイナイトの略称、“Ｐ”はパーライトの
略称で、図中の“粗粒α＋Ｂ”がＡｌ鋼板、“α＋Ｐ”
がＡ２鋼板、“細粒α＋Ｂ”がＡ３鋼板である。図から
わかるように、ＹＲ値は引張試験における歪速度が大き
くなるほど上昇する。しかし、フェライト＋パーライト
組織よりもフェライト＋ベイナイト組織の方が上昇程度
が低い。フェライト＋ベイナイト組織の中ではフェライ
トが粗粒なほど、高歪速度（＞０．１／秒）で低ＹＲ値
が得られることがわかった。粗粒フェライトとベイナイ
トの混合組織にすることで歪速度１０／秒でもＹＲ＜８
０％以下が達成されている。本発明で、粗粒フェライト
とはＡＳＴＭ粒度Ｎｏ．１１以下のものを言う。Means for Solving the Problems In order to solve this problem, the present inventors have intensively studied the relationship between the microstructure and YR at a high strain rate, and have found the following important findings. First, FIG. 1 shows the relationship between the tensile strain rate and the yield ratio (= yield strength / tensile strength) using the A1 to A3 steel sheets in Table 2 as test materials. The abbreviation “B” for ferrite is an abbreviation for bainite, “P” is an abbreviation for pearlite, and “coarse grain α + B” in the figure is an Al steel sheet, “α + P”
Is an A2 steel sheet, and “fine grain α + B” is an A3 steel sheet. As can be seen from the figure, the YR value increases as the strain rate in the tensile test increases. However, the degree of rise is lower in the ferrite + bainite structure than in the ferrite + pearlite structure. It was found that in the ferrite + bainite structure, the coarser the ferrite, the lower the YR value at a higher strain rate (> 0.1 / sec). By forming a mixed structure of coarse ferrite and bainite, YR <8 even at a strain rate of 10 / sec.
0% or less has been achieved. In the present invention, the coarse ferrite is an ASTM particle size No. 11 or less.
【００１０】図２はＡ鋼と同鋼種において酸素のみ１９
〜４４ｐｐｍの範囲で変化させた鋼を供試鋼に用いて、
粗粒フェライト（ＡＳＴＭ粒度Ｎｏ．＝９〜１１）とベ
イナイト混合組織の高歪速度（＝１０／秒）の繰り返し
予歪を与えた後の vＥ-5に及ぼす酸素含有量の影響を調
べたものである。高歪速度（＝１０／秒）の繰り返し予
歪を与えた後の靭性は、図２に示すようにかなりのバラ
ツキを有しているが、その下限値は酸素含有量により支
配され、酸素含有量を３０ｐｐｍ以下にすることで vＥ
-5（ｍｉｎｉｍｕｍ）＞１００Ｊを満たす安定した靭性
が得られることがわかった。これは、酸素含有量を３０
ｐｐｍ以下にすることで、高速繰り返し予定歪の時にマ
イクロ歪集中源となる鋼中酸化物が減少、微細化したた
めである。FIG. 2 shows that only oxygen 19
Using steel changed in the range of ~ 44 ppm for the test steel,
Examination of the effect of oxygen content on vE-5 after repeated pre-straining of high-strain rate (= 10 / sec) of a mixture of coarse ferrite (ASTM grain size No. = 9-11) and bainite It is. As shown in FIG. 2, the toughness after repeated pre-straining at a high strain rate (= 10 / sec) has considerable variation, but the lower limit is governed by the oxygen content, and VE by reducing the amount to 30 ppm or less
It was found that stable toughness satisfying -5 (minimum)> 100 J was obtained. This reduces the oxygen content to 30
This is because, by setting the content to less than ppm, oxides in the steel, which are sources of micro-strain at the time of high-speed repeated scheduled strain, were reduced and refined.
【００１１】さらに、本発明者らは、（Ｍｏ＋３．５Ｖ
＋２０Ｎｂ）量を変化させた５０キロ級鋼種を用いて、
粗粒フェライトとベイナイトの混合組織の鋼に対し、常
温で高歪速度（＝１０／秒））での引張試験を行うとと
もに、６００℃でＪＩＳ Ｇ０５６７に定められた歪速
度（＝０．３％／分）でも引張試験を行った。その結果
を図３に示す。（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量が０．
１２％未満の場合、高温強度（０．２％耐力）が常温で
のＹＳの２／３（目標値）を満足しない。また、０．８
％を超えて（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量を増加する
と、高歪速度でのＹＲ値が８０％を超えてしまう。した
がって、（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量を０．１２％
以上０．８％以下に限定した。Further, the present inventors have found that (Mo + 3.5 V
+ 20Nb) Using a 50 kg grade steel with varying amounts,
A tensile test was performed on steel having a mixed structure of coarse-grained ferrite and bainite at a high strain rate (= 10 / sec) at room temperature, and at 600 ° C., a strain rate (= 0.3%) specified in JIS G0567. / Min) also performed a tensile test. The result is shown in FIG. (Mo + 3.5V + 20Nb) amount is 0.
If it is less than 12%, the high-temperature strength (0.2% proof stress) does not satisfy （(target value) of YS at normal temperature. Also, 0.8
When the amount exceeds (Mo + 3.5V + 20Nb), the YR value at a high strain rate exceeds 80%. Therefore, the (Mo + 3.5V + 20Nb) amount is reduced to 0.12%
It was limited to 0.8% or less.
【００１２】以上のことから、高歪速度で変形を受ける
場合にも低ＹＲ（≦８０％）であり、高歪速度で繰り返
し予歪を受けた後も安定して優れた靭性を示し、かつ耐
火性に優れた、活断層近傍の構造物の塑性耐震設計と耐
火設計を組み合わせた設計を可能にする耐震鋼材の必要
条件は、０．１２％≦（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）％
≦０．８％を満足し、酸素含有量が３０ｐｐｍ以下で粗
粒フェライトとベイナイトの混合組織の特徴を有するも
のであることがわかった。From the above, the low YR (≦ 80%) even when deformed at a high strain rate, stable and excellent toughness after repeated pre-strain at a high strain rate, and The necessary condition of the seismic steel material that enables the design combining the plastic seismic design and the fire resistant design of the structure near the active fault with excellent fire resistance is 0.12% ≦ (Mo + 3.5V + 20Nb)%
It was found that the composition satisfies ≦ 0.8% and has an oxygen content of 30 ppm or less and has characteristics of a mixed structure of coarse-grained ferrite and bainite.
【００１３】本発明はこれらの知見に基づいてなされた
もので、 （１）重量比で、Ｃ：０．０４〜０．１８％，Ｓｉ：
０．０５〜０．４％，Ｍｎ：０．６〜１．７％，Ｍｏ：
０．１〜０．６％，Ｖ：０．００５〜０．１％，Ａｌ：
０．００１〜０．０６％，Ｎ≦３０ｐｐｍ，Ｏ≦３０ｐ
ｐｍで、かつ０．１２％≦（Ｍｏ＋３．５Ｖ）％≦０．
８％を満足し、残部がＦｅおよび不可避的不純物からな
る鋼をオーステナイト域で熱間圧延後、Ａｒ3 点経過後
から水冷し、６５０℃以下４００℃以上で水冷を停止し
て、主たる組織を粗粒フェライトとベイナイトの２相組
織にすることを特徴とする耐火性に優れた耐震性建築鋼
材の製造方法。The present invention has been made based on these findings. (1) By weight ratio, C: 0.04 to 0.18%, Si:
0.05-0.4%, Mn: 0.6-1.7%, Mo:
0.1-0.6%, V: 0.005-0.1%, Al:
0.001-0.06%, N ≦ 30ppm, O ≦ 30p
pm and 0.12% ≦ (Mo + 3.5V)% ≦ 0.
After hot rolling a steel which satisfies 8% and the balance is Fe and unavoidable impurities in the austenite region, water cooling is performed after the lapse of three points of Ar, and water cooling is stopped at 650 ° C or lower and 400 ° C or higher, and the main structure is changed. A method for producing an earthquake-resistant building steel excellent in fire resistance, characterized by having a two-phase structure of coarse ferrite and bainite.
【００１４】（２）重量比で、Ｃ：０．０４〜０．１８
％，Ｓｉ：０．０５〜０．４％，Ｍｎ：０．６〜１．７
％，Ｍｏ：０．１〜０．６％，Ｖ：０．００５〜０．１
％，Ａｌ：０．００１〜０．０６％，Ｎ≦３０ｐｐｍ，
Ｏ≦３０ｐｐｍで、かつ０．１２％≦（Ｍｏ＋３．５
Ｖ）％≦０．８％を満足することに加えて、Ｃｕ：０．
０５〜０．６％，Ｎｉ：０．０５〜０．６％，Ｃｒ：
０．０５〜１．０％，Ｔｉ：０．００５〜０．０１５％
のうち１種または２種以上を含み、残部がＦｅおよび不
可避的不純物からなる鋼をオーステナイト域で熱間圧延
後、Ａｒ3 点経過後から水冷し、６５０℃以下４００℃
以上で水冷を停止して、主たる組織を粗粒フェライトと
ベイナイトの２相組織にすることを特徴とする耐火性に
優れた耐震性建築鋼材の製造方法。(2) C: 0.04 to 0.18 by weight
%, Si: 0.05 to 0.4%, Mn: 0.6 to 1.7
%, Mo: 0.1 to 0.6%, V: 0.005 to 0.1
%, Al: 0.001 to 0.06%, N ≦ 30 ppm,
O ≦ 30 ppm and 0.12% ≦ (Mo + 3.5
V) In addition to satisfying% ≦ 0.8%, Cu: 0.
05-0.6%, Ni: 0.05-0.6%, Cr:
0.05 to 1.0%, Ti: 0.005 to 0.015%
After hot rolling in the austenitic region a steel containing at least one of Fe and unavoidable impurities, water-cooled after the lapse of three points of Ar, 650 ° C or lower and 400 ° C
A method for producing an earthquake-resistant building steel excellent in fire resistance, characterized by stopping water cooling as described above and changing the main structure to a two-phase structure of coarse-grain ferrite and bainite.
【００１５】（３）鋼は、上記（１）または（２）の成
分に加えて、さらにＮｂ：０．００５〜０．０４％を含
有し、かつ０．１２％≦（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）
％≦０．８％を満足することを特徴とする耐火性に優れ
た耐震性建築鋼材の製造方法である。(3) The steel further contains Nb: 0.005 to 0.04% in addition to the component (1) or (2), and 0.12% ≦ (Mo + 3.5V + 20Nb)
% ≦ 0.8%, which is a method for producing an earthquake-resistant building steel excellent in fire resistance.
【００１６】[0016]
【発明の実施の形態】次に、本発明にかかる鋼材の各成
分の添加理由および添加量を限定した理由を説明する。
Ｃ，Ｓｉ，Ｍｎ，Ａｌは、通常の溶接構造用鋼において
所要の材質を得るために、従来から確認されている作用
・効果の関係をもとに、以下のごとく限定した。Next, the reason for adding each component of the steel material according to the present invention and the reason for limiting the amount of addition will be described.
C, Si, Mn, and Al were limited as follows based on the relationship between the functions and effects that have been conventionally confirmed in order to obtain required materials in ordinary welded structural steel.
【００１７】Ｃは、最も安価な元素で高強度化に有効な
元素であるが、０．１８％を超えて添加すると溶接性が
著しく低下する。０．０４％未満では、厚物で強度が不
足し、多量の合金元素の添加が必要となり、コスト高を
招く。したがって、Ｃは０．０４％以上０．１８％以下
に限定した。C is the most inexpensive element and is effective for increasing the strength. However, if it is added in excess of 0.18%, the weldability is significantly reduced. If it is less than 0.04%, the strength of a thick material is insufficient, and a large amount of alloying elements must be added, resulting in an increase in cost. Therefore, C is limited to 0.04% or more and 0.18% or less.
【００１８】Ｓｉは、鋼材の強度、溶鋼の予備脱酸に必
要な元素である。予備脱酸のためには、０．０５％以上
の添加が必要である。０．４％を超える過剰の添加は、
鋼材の靭性、溶接ＨＡＺ靭性を劣化させる。したがっ
て、Ｓｉ量は０．０５％以上０．４％以下に限定した。Si is an element necessary for the strength of steel and the preliminary deoxidation of molten steel. For pre-deoxidation, addition of 0.05% or more is necessary. An excess addition of more than 0.4%
It degrades the toughness of the steel material and the weld HAZ toughness. Therefore, the amount of Si is limited to 0.05% or more and 0.4% or less.
【００１９】Ｍｎは、母材の強度を確保するため、必要
な元素である。０．６％未満では、厚物で強度が不足
し、多量の合金元素の添加が必要となり、コスト高を招
く。また、Ｍｎは中央偏析しやすい元素である。１．７
％を超えて添加すると、板厚中央が著しく脆化する。し
たがって、Ｍｎの範囲を０．６％以上１．７％以下に限
定した。Mn is an element necessary for securing the strength of the base material. If it is less than 0.6%, the strength is insufficient for a thick material, and a large amount of alloying elements must be added, resulting in an increase in cost. Further, Mn is an element that is easily segregated at the center. 1.7
%, The center of the sheet thickness becomes significantly embrittled. Therefore, the range of Mn is limited to 0.6% or more and 1.7% or less.
【００２０】Ｍｏは、鋼の中、高温強度向上に有効な元
素である。このような効果を発揮するためには、０．１
％以上の添加が必要である。０．６％を超えるＭｏの添
加は、降伏比を著しく上昇させる。したがって、Ｍｏを
０．１％以上０．６％以下に限定した。Mo is an element effective in improving the high-temperature strength in steel. In order to exhibit such an effect, 0.1
% Or more is required. The addition of Mo in excess of 0.6% significantly increases the yield ratio. Therefore, Mo is limited to 0.1% or more and 0.6% or less.
【００２１】Ｎｂ，Ｖは、微量添加により常温、高温強
度の上昇に有効な元素である。Ｎｂ＜０．００５％、Ｖ
＜０．００５％では、明瞭な強度上昇効果が認められな
い。０．０４％を超えるＮｂの添加、０．１％を超える
Ｖの添加は、降伏比を著しく上昇させる。したがって、
Ｎｂを０．００５％以上０．０４％以下、Ｖを０．００
５％以上０．１％以下に限定した。Nb and V are effective elements for increasing the strength at room temperature and high temperature when added in a small amount. Nb <0.005%, V
At <0.005%, no clear increase in strength is observed. The addition of Nb exceeding 0.04% and the addition of V exceeding 0.1% significantly increase the yield ratio. Therefore,
Nb is 0.005% or more and 0.04% or less, and V is 0.00
It is limited to 5% or more and 0.1% or less.
【００２２】Ａｌは、脱酸に必要な元素である。Ａｌ量
として０．００１％未満では、十分な脱酸効果が期待で
きない。また、０．０６％を超えて過剰に添加すると、
連続鋳造スラブの表面にキズが発生しやすい。したがっ
て、Ａｌ量は０．００１％以上０．０６％以下に限定し
た。Al is an element necessary for deoxidation. If the Al content is less than 0.001%, a sufficient deoxidizing effect cannot be expected. When added in excess of 0.06%,
The surface of the continuous casting slab is easily scratched. Therefore, the amount of Al is limited to 0.001% or more and 0.06% or less.
【００２３】Ｎは、固体鋼中に固溶Ｎや窒化物系介在物
として存在する。固溶Ｎや粗大窒化物系介在物は、鋼の
靭性を劣化させる。３０ｐｐｍを超えてＮを含有する
と、固溶Ｎが存在する。また、最終凝固部には粗大な窒
化物（例えばＴｉＮやＮｂＮ）が生成しやすくなり、優
れた靭性が得られない。したがって、Ｎ含有量を３０ｐ
ｐｍ以下に規制した。N exists as solid solution N or nitride-based inclusions in solid steel. Solid solution N and coarse nitride-based inclusions deteriorate the toughness of steel. When N is contained in excess of 30 ppm, solid solution N exists. In addition, coarse nitrides (for example, TiN and NbN) are easily generated in the final solidified portion, and excellent toughness cannot be obtained. Therefore, the N content is 30p
pm or less.
【００２４】Ｏは、既に述べたように、酸素含有量を３
０ｐｐｍ以下にすることで、高速繰り返し予歪を与えた
時にマイクロ歪集中源となる鋼中酸化物を減少、微細化
するためであり、３０ｐｐｍを越えると、 vＥ-5（mini
mum ）＞１００Ｊを満たす安定した靭性を得ることがで
きない。O has an oxygen content of 3 as described above.
By setting the content to 0 ppm or less, oxides in the steel, which are sources of micro-strain concentration when high-speed repetitive pre-strain is given, are reduced and refined.
mum) Stable toughness satisfying> 100 J cannot be obtained.
【００２５】（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量は、既に
述べたように、０．１２％未満の場合、高温強度（０．
２％耐力）が常温でのＹＳの２／３（目標値）を満足し
ない。また、（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量が０．８
％を越えると、高歪速度でのＹＲ値が８０％を越えてし
まう。従って、（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量を０．
１２％以上０．８以下に限定した。なお、Ｎｂを添加し
ない場合、（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量は（Ｍｏ＋
３．５Ｖ）量となる。As described above, when the (Mo + 3.5V + 20Nb) amount is less than 0.12%, the high-temperature strength (0.
2% yield strength) does not satisfy （(target value) of YS at room temperature. In addition, (Mo + 3.5V + 20Nb) amount is 0.8
%, The YR value at a high strain rate exceeds 80%. Therefore, the amount of (Mo + 3.5V + 20Nb) is set to 0.
It is limited to 12% or more and 0.8 or less. When Nb was not added, the amount of (Mo + 3.5V + 20Nb) was (Mo + 3.5V + 20Nb).
3.5V).
【００２６】Ｃｕ，Ｎｉ，Ｃｒは、固溶強化や焼入性向
上効果を通して、高強度化に寄与する。Ｃｕ＜０．０５
％，Ｎｉ＜０．０５％，Ｃｒ＜０．０５％では、明瞭な
強度上昇効果が見られない。０．６％を超えるＣｕの添
加は、著しくＣｕ割れ発生の危険性を増大させる。Ｎｉ
は高価な元素でありコストの観点から、上限を０．６％
とした。１％を超えるＣｒの添加は溶接性を著しく劣化
させる。したがって、Ｃｕを０．０５％以上０．６％以
下、Ｎｉを０．０５％以上０．６％以下、Ｃｒを０．０
５％以上１％以下に限定した。Cu, Ni and Cr contribute to high strength through solid solution strengthening and hardenability improving effects. Cu <0.05
%, Ni <0.05% and Cr <0.05%, no clear effect of increasing the strength is observed. Addition of Cu exceeding 0.6% significantly increases the risk of Cu cracking. Ni
Is an expensive element, and the upper limit is 0.6% from the viewpoint of cost.
And Addition of more than 1% of Cr significantly deteriorates weldability. Therefore, Cu is 0.05% or more and 0.6% or less, Ni is 0.05% or more and 0.6% or less, and Cr is 0.0% or more.
It is limited to 5% or more and 1% or less.
【００２７】Ｔｉは、ＴｉＮの溶接ＨＡＺ部の組織粗大
化を抑制してＨＡＺ靭性の向上に寄与する元素である。
０．００５％未満のＴｉ添加では、ＨＡＺ靭性向上効果
が発揮されない。０．０１５％を超えて添加すると溶接
の冷却過程でＴｉＣが析出し、ＨＡＺ靭性の劣化を招
く。したがって、Ｔｉを０．００５％以上、０．０１５
％以下に限定した。Ti is an element that suppresses the coarsening of the structure of the welded HAZ of TiN and contributes to the improvement of the HAZ toughness.
If less than 0.005% of Ti is added, the effect of improving the HAZ toughness is not exhibited. If it is added in an amount exceeding 0.015%, TiC precipitates during the cooling process of welding, leading to deterioration of HAZ toughness. Therefore, the content of Ti is set to 0.005% or more,
% Or less.
【００２８】Ｐ，Ｓは、本特許の目的とする耐震性と直
接的な関係は無いが、溶接性や板厚方向の延性の観点か
ら低い方が望ましい。また、介在物形態制御の観点か
ら、適量のＣａの添加やＲＥＭの添加は望ましい。Although P and S do not have a direct relationship with the seismic resistance, which is the object of the present invention, it is desirable that P and S are low from the viewpoint of weldability and ductility in the thickness direction. From the viewpoint of inclusion morphology control, it is desirable to add an appropriate amount of Ca or REM.
【００２９】そして、本発明にかかる鋼材の主たるミク
ロ組織は、粗粒フェライトとベイナイトの混合組織であ
る。この混合組織とする理由は、高歪速度（＞０．１／
秒）で低ＹＲ値が得られるためである。The main microstructure of the steel according to the present invention is a mixed structure of coarse ferrite and bainite. The reason for this mixed structure is that a high strain rate (> 0.1 /
This is because a low YR value can be obtained in seconds.
【００３０】本発明方法ではこのミクロ組織を得るため
に、以下の製造条件で鋼材を製造する。まず、上記成分
範囲を満足する鋼をオーステナイト域で熱間圧延する。
オーステナイト域で熱間圧延する理由は、フェライト域
で圧延すると加工硬化し、通常の歪速度（１０-2／秒前
後）において低ＹＲが得られないからである。ついで、
Ａｒ3 点経過後から水冷する。Ａｒ3 点経過後から水冷
する理由は、オーステナイト域から加速冷却する場合に
は、その鋼の焼入性に応じて冷却速度を制御しなければ
フェライトは得られ難いが、Ａｒ3 点経過後まで放冷
し、一部フェライトが析出してから加速冷却した場合、
非常に広い冷却速度範囲で低ＹＲが得られるためであ
る。図４は供試鋼にＡ鋼を用いて、オーステナイト域か
ら加速冷却した場合と、圧延後Ａｒ3 点経過後まで放冷
し、一部フェライトが析出した２相域から加速冷却した
場合のＹＲと冷却速度の関係を示している。後者の場合
には非常に広い冷却速度範囲で低ＴＲが得られている。
そしてミクロ組織観察から、後者の場合には広い冷却速
度範囲でフェライトとベイナイトの混合組織が得られた
ためであることが判明した。ついで６５０℃以下４００
℃以上で水冷を停止して、組織をフェライトとベイナイ
トの２相組織にする。この温度範囲に限定した理由は、
停止温度が６５０℃を越える高温の場合には、組織がフ
ェライト＋パーライト組織になってしまい、また、停止
温度が４００℃を下回る低温の場合には、マルテンサイ
トが混入し著しく靭性が劣化してしまうためである。こ
のような処理を行うことにより、鋼材の主たる組織を粗
粒フェライトとベイナイトの混合組織とすることができ
る。In the method of the present invention, in order to obtain this microstructure, a steel material is manufactured under the following manufacturing conditions. First, a steel satisfying the above component range is hot-rolled in an austenite region.
The reason for hot rolling in the austenitic region is that when rolling is performed in the ferrite region, work hardening occurs and a low YR cannot be obtained at a normal strain rate (around 10 -2 / sec). Then
Ar cooling is performed after 3 points. The reason for water cooling after the elapse of Ar 3 points is that when accelerated cooling from the austenite region, ferrite is difficult to obtain unless the cooling rate is controlled according to the hardenability of the steel, but until after the elapse of Ar 3 points If allowed to cool and accelerated cooling after some ferrite precipitates,
This is because a low YR can be obtained in a very wide cooling rate range. Fig. 4 shows the YRs when the steel A was used as the test steel and the steel was accelerated and cooled from the austenite region, and when the steel was allowed to cool down after the elapse of three points of Ar after rolling and was accelerated and cooled from the two-phase region where some ferrite was precipitated. And the relationship between the cooling rate. In the latter case, a low TR is obtained in a very wide cooling rate range.
From the microstructure observation, it was found that in the latter case, a mixed structure of ferrite and bainite was obtained in a wide cooling rate range. Then 650 ° C or lower 400
The water cooling is stopped at a temperature of not less than ° C. to change the structure to a two-phase structure of ferrite and bainite. The reason for limiting to this temperature range is that
If the stop temperature is higher than 650 ° C., the structure becomes ferrite + pearlite structure, and if the stop temperature is lower than 400 ° C., martensite is mixed and the toughness is significantly deteriorated. This is because By performing such a treatment, the main structure of the steel material can be a mixed structure of coarse-grained ferrite and bainite.
【００３１】[0031]
【実施例】次に本発明の実施例を説明する。表１、表２
に、供試鋼の化学成分を示す。鋼Ａ〜Ｎは本発明範囲内
の鋼組成を有し、鋼Ｏ〜Ｙは本発明範囲外の鋼組成を有
する。ここで、鋼Ｊ，Ｋ，Ｌ，Ｓ，Ｖ，ＸはＴＳ５７０
ＭＰａ級、鋼Ｍ，Ｎ，ＹはＴＳ４００ＭＰａ級の鋼であ
り、その他はＴＳ４９０ＭＰａ級の鋼である。すべて、
軽圧下プロセスを含む連続鋳造にてスラブにされた。上
記の鋼を表３に示す製造条件にて鋼板とした。表４、表
５には得られた鋼板のミクロ組織ならびに通常の歪速度
（＝０．０１／秒）、高歪速度（＝１０／秒）での常温
引張特性、および高温強度、さらに予歪なしの場合、な
らびに高歪速度（＝１０／秒）で±１＋２＋４％の繰り
返し予歪を与えた後のシャルピー衝撃試験結果を併記し
てある。Next, embodiments of the present invention will be described. Table 1, Table 2
The chemical composition of the test steel is shown below. Steels A to N have a steel composition within the scope of the invention, and steels O to Y have a steel composition outside the scope of the invention. Here, steels J, K, L, S, V, and X are TS570
The MPa class and the steels M, N, and Y are TS400 MPa class steels, and the others are TS490 MPa class steels. all,
The slab was made by continuous casting including a light reduction process. The above steel was used as a steel plate under the manufacturing conditions shown in Table 3. Tables 4 and 5 show the microstructure of the obtained steel sheet and the normal-temperature tensile properties at normal strain rate (= 0.01 / sec), high strain rate (= 10 / sec), high-temperature strength, and pre-strain. The chart also shows the results of the Charpy impact test in the case of none and after the repeated prestrain of ± 1 + 2 + 4% at a high strain rate (= 10 / sec).
【００３２】常温引張試験片は１／４ｔよりＣ方向に採
取された１２ｍｍ角×平行部長さ１００ｍｍ角の棒試験
片である。この試験片に対し、サーボ式の試験機でスト
ローク速度１ｍ／秒、すなわち歪速度１０／秒で引張試
験を行った。また、同上試験片をストローク速度１ｍ／
秒、すなわち歪速度１０／秒で、１％の圧縮塑性変形→
１％の引張塑性変形→２％の圧縮塑性変形→２％の引張
塑性変形→４％の圧縮塑性変形→４％の引張塑性変形と
いう繰り返し予歪を与えた後、シャルピー衝撃試験片を
採取し、 vＴs 並びに vＥ-5を測定した。−５℃では９
本のシャルピー衝撃試験を実施し、その平均値と最小値
を求めた。さらに、高温引張試験片は１／４ｔよりＣ方
向に採取された１０φ×５０ＧＬの丸棒試験片である。The room temperature tensile test specimen is a rod specimen of 12 mm square × 100 mm square parallel part length sampled in the C direction from 1/4 t. This specimen was subjected to a tensile test at a stroke speed of 1 m / sec, that is, a strain speed of 10 / sec, using a servo-type testing machine. In addition, the same test specimen was used at a stroke speed of 1 m /
Seconds, ie 1% compression plastic deformation at a strain rate of 10 / sec →
1% tensile plastic deformation → 2% compressive plastic deformation → 2% tensile plastic deformation → 4% compressive plastic deformation → 4% tensile plastic deformation , VTs and vE-5 were measured. 9 at -5 ° C
The Charpy impact test of the book was performed, and the average value and the minimum value were obtained. Further, the high-temperature tensile test piece is a 10φ × 50GL round bar test piece taken in the C direction from 1 / 4t.
【００３３】表４をみると、酸素含有量３０ｐｐｍ以下
で０．１２％≦（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）≦０．８
％を満足し粗粒フェライト（ＡＳＴＭ Ｎｏ．９〜１
１）とベイナイトの混合組織（ベイナイト率４０〜７０
％）を有した本発明鋼板（Ａ１，Ｂ１，Ｃ１，Ｄ１，Ｅ
１，Ｆ１，Ｇ１，Ｈ１，Ｉ１，Ｊ１，Ｋ１，Ｌ１，Ｍ
１，Ｎ１）は、高歪速度でのＹＲが８０％以下で、高温
強度が目標値を満足し、繰り返し歪後も vＥ-5の最小値
が１５０Ｊ以上の靭性を有している。フェライト＋パー
ライト組織であるＡ３，Ｃ２，Ｍ２は、高歪速度の場
合、通常の引張試験に比べＹＲの上昇が著しく、８０％
を越える値になっている。また、それらの鋼は高歪速度
の繰り返し予歪後著しく靭性が劣化し、室温近傍の vＴ
s を示している。細粒フェライト（ＡＳＴＭ Ｎｏ．１
１超え）とベイナイトの混合組織であるＡ２，Ｅ２，Ｊ
２鋼板は、高歪速度の引張試験のＹＲが８０％を超えて
いる。さらに、粗粒フェライトとベイナイトとマルテン
サイトの混合組織であるＢ２，Ｆ２鋼板は、通常の歪速
度での引張試験及び高歪速度での引張試験でのＹＲが８
０％を超えるとともに、靭性も低い。また、組織は粗粒
フェライトとベイナイトの混合組織であっても（Ｍｏ＋
３．５Ｖ＋２０Ｎｂ）＜０．１２％であるＯ１，Ｐ１，
Ｑ１，Ｒ１は高温強度が目標値を満足していない。組織
が粗粒フェライトとベイナイトの混合組織で、（Ｍｏ＋
３．５Ｖ＋２０Ｎｂ）＞０．８％であるＳ１，Ｔ１，Ｕ
１は、高歪速度でのＹＲが８０％を超えている。組織が
粗粒フェライトとベイナイトの混合組織で、酸素含有量
が３０ｐｐｍを超えているＶ１，Ｗ１，Ｘ１，Ｙ１は高
歪速度の繰り返し予歪後の vＥ-5の最小値が４７Ｊを下
回っている。Referring to Table 4, when the oxygen content is 30 ppm or less, 0.12% ≦ (Mo + 3.5V + 20Nb) ≦ 0.8.
% And satisfying the requirements of coarse ferrite (ASTM Nos. 9 to 1).
1) and a mixed structure of bainite (bainite ratio 40 to 70)
% Of the present invention (A1, B1, C1, D1, E)
1, F1, G1, H1, I1, J1, K1, L1, M
1, N1) has a high temperature strength of not more than 80% at a high strain rate, a high temperature strength satisfying a target value, and a minimum value of vE-5 of 150 J or more even after repeated strain. A3, C2, and M2, which are ferrite + pearlite structures, show a marked increase in YR at a high strain rate as compared with a normal tensile test, and have a 80%
It exceeds the value. In addition, the toughness of these steels deteriorates significantly after cyclic prestraining at high strain rates, and vT near room temperature
s. Fine grain ferrite (ASTM No. 1)
A2, E2, J, which is a mixed structure of bainite
The two steel plates have a high strain rate YR of more than 80% in a tensile test. Further, the B2, F2 steel sheet having a mixed structure of coarse ferrite, bainite and martensite has a YR of 8 in a tensile test at a normal strain rate and a tensile test at a high strain rate.
It exceeds 0% and has low toughness. Further, even when the structure is a mixed structure of coarse ferrite and bainite (Mo +
O1, P1, with 3.5V + 20Nb) <0.12%
As for Q1 and R1, the high temperature strength does not satisfy the target value. The structure is a mixed structure of coarse ferrite and bainite, and (Mo +
S1, T1, U with 3.5V + 20Nb)> 0.8%
In No. 1, the YR at a high strain rate exceeds 80%. For V1, W1, X1, and Y1 having a mixed structure of coarse-grained ferrite and bainite and having an oxygen content exceeding 30 ppm, the minimum value of vE-5 after repeated prestraining at a high strain rate is less than 47 J. .
【００３４】[0034]
【表１】 [Table 1]
【００３５】[0035]
【表２】 [Table 2]
【００３６】[0036]
【表３】 [Table 3]
【００３７】[0037]
【表４】 [Table 4]
【００３８】[0038]
【表５】 [Table 5]
【００３９】[0039]
【発明の効果】以上の実施例から明らかなように、本発
明方法により製造された鋼材は、高歪速度で変形を受け
る場合にも低ＹＲ（≦８０％）を示し、高歪速度で繰り
返し予歪を受けた後も安定して優れた靭性を示し、かつ
優れた耐火性を示すので、活断層近傍の構造物の塑性耐
震設計と耐火設計を組み合わせた設計を可能にする。ま
た、鋼材の大量生産も可能である。As is apparent from the above examples, the steel material produced by the method of the present invention exhibits a low YR (≦ 80%) even when it is deformed at a high strain rate, and is repeatedly repeated at a high strain rate. Since it exhibits excellent toughness and excellent fire resistance even after being subjected to prestrain, it enables the design near the active fault to be combined with plastic seismic design and fire resistant design. Mass production of steel is also possible.
【図面の簡単な説明】[Brief description of the drawings]
【図１】引張歪速度と降伏比（＝降伏強度／引張強度）
の関係を示した図。Fig. 1 Tensile strain rate and yield ratio (= yield strength / tensile strength)
FIG.
【図２】酸素含有量と高歪速度で繰り返し塑性歪（±１
＋２＋４％）を与えた後、−５℃で試験したシャルピー
衝撃吸収エネルギー(vＥ-5）の関係を示した図。FIG. 2 shows cyclic plastic strain (± 1) at high oxygen content and high strain rate.
(+ 2 + 4%), and shows the relationship between Charpy impact absorption energy (vE-5) tested at -5 ° C.
【図３】（Ｍｏ＋３．５Ｖ＋２０Ｎｂ）量と高歪速度
（＝１０／秒）での降伏比および高温強度（６００℃で
の０．２％耐力）との関係を示した図。FIG. 3 is a graph showing the relationship between the amount of (Mo + 3.5V + 20Nb), the yield ratio at a high strain rate (= 10 / sec), and the high-temperature strength (0.2% proof stress at 600 ° C.).
【図４】常温でのＹＲと冷却速度の関係を示した図。FIG. 4 is a diagram showing the relationship between YR and cooling rate at room temperature.
Claims (3)
Ｓｉ：０．０５〜０．４％，Ｍｎ：０．６〜１．７％，
Ｍｏ：０．１〜０．６％，Ｖ：０．００５〜０．１％，
Ａｌ：０．００１〜０．０６％，Ｎ≦３０ｐｐｍ，Ｏ≦
３０ｐｐｍで、かつ０．１２％≦（Ｍｏ＋３．５Ｖ）％
≦０．８％を満足し、残部がＦｅおよび不可避的不純物
からなる鋼をオーステナイト域で熱間圧延後、Ａｒ3 点
経過後から水冷し、６５０℃以下４００℃以上で水冷を
停止して、主たる組織を粗粒フェライトとベイナイトの
２相組織にすることを特徴とする耐火性に優れた耐震性
建築鋼材の製造方法。1. A weight ratio of C: 0.04 to 0.18%,
Si: 0.05 to 0.4%, Mn: 0.6 to 1.7%,
Mo: 0.1 to 0.6%, V: 0.005 to 0.1%,
Al: 0.001 to 0.06%, N ≦ 30 ppm, O ≦
30 ppm and 0.12% ≦ (Mo + 3.5V)%
≦ 0.8%, the balance of steel consisting of Fe and unavoidable impurities is hot-rolled in the austenite region, and water-cooled after the lapse of three points of Ar, and water-cooling is stopped at 650 ° C or lower and 400 ° C or higher, A method for producing an earthquake-resistant building steel excellent in fire resistance, characterized in that a main structure is a two-phase structure of coarse-grain ferrite and bainite.
Ｓｉ：０．０５〜０．４％，Ｍｎ：０．６〜１．７％，
Ｍｏ：０．１〜０．６％，Ｖ：０．００５〜０．１％，
Ａｌ：０．００１〜０．０６％，Ｎ≦３０ｐｐｍ，Ｏ≦
３０ｐｐｍで、かつ０．１２％≦（Ｍｏ＋３．５Ｖ）％
≦０．８％を満足することに加えて、Ｃｕ：０．０５〜
０．６％，Ｎｉ：０．０５〜０．６％，Ｃｒ：０．０５
〜１．０％，Ｔｉ：０．００５〜０．０１５％のうち１
種または２種以上を含み、残部がＦｅおよび不可避的不
純物からなる鋼をオーステナイト域で熱間圧延後、Ａｒ
3 点経過後から水冷し、６５０℃以下４００℃以上で水
冷を停止して、主たる組織を粗粒フェライトとベイナイ
トの２相組織にすることを特徴とする耐火性に優れた耐
震性建築鋼材の製造方法。2. C: 0.04 to 0.18% by weight,
Si: 0.05 to 0.4%, Mn: 0.6 to 1.7%,
Mo: 0.1 to 0.6%, V: 0.005 to 0.1%,
Al: 0.001 to 0.06%, N ≦ 30 ppm, O ≦
30 ppm and 0.12% ≦ (Mo + 3.5V)%
≦ 0.8%, Cu: 0.05-
0.6%, Ni: 0.05 to 0.6%, Cr: 0.05
1.0%, Ti: 0.005 to 0.015%
After hot rolling in the austenitic region a steel containing one or more kinds, the balance being Fe and unavoidable impurities,
After three points, water cooling is performed, and water cooling is stopped at 650 ° C or lower and 400 ° C or higher, and the main structure is a two-phase structure of coarse-grained ferrite and bainite. Production method.
成分に加えて、さらにＮｂ：０．００５〜０．０４％を
含有し、かつ０．１２％≦（Ｍｏ＋３．５Ｖ＋２０Ｎ
ｂ）％≦０．８％を満足することを特徴とする耐火性に
優れた耐震性建築鋼材の製造方法。3. The steel further contains 0.005 to 0.04% of Nb in addition to the components described in claim 1 or 2, and 0.12% ≦ (Mo + 3.5V + 20N).
b) A method for producing an earthquake-resistant building steel excellent in fire resistance, characterized by satisfying% ≦ 0.8%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25022296A JP3371712B2 (en) | 1996-09-20 | 1996-09-20 | Manufacturing method of earthquake resistant building steel with excellent fire resistance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25022296A JP3371712B2 (en) | 1996-09-20 | 1996-09-20 | Manufacturing method of earthquake resistant building steel with excellent fire resistance |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH1096024A true JPH1096024A (en) | 1998-04-14 |
| JP3371712B2 JP3371712B2 (en) | 2003-01-27 |
Family
ID=17204659
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25022296A Expired - Fee Related JP3371712B2 (en) | 1996-09-20 | 1996-09-20 | Manufacturing method of earthquake resistant building steel with excellent fire resistance |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3371712B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008059669A1 (en) | 2006-11-14 | 2008-05-22 | Nippon Steel Corporation | Refractory steel material with excellent welded-joint toughness and process for producing the same |
| US8715432B2 (en) | 2008-03-31 | 2014-05-06 | Nippon Steel & Sumitomo Metal Corporation | Fire-resistant steel superior in weld joint reheat embrittlement resistance and toughness and method of production of same |
| WO2021046882A1 (en) * | 2019-09-09 | 2021-03-18 | 王平 | Earthquake-resistant, fire-resistant, high-strength and high-toughness stainless structural steel and preparation method therefor |
-
1996
- 1996-09-20 JP JP25022296A patent/JP3371712B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008059669A1 (en) | 2006-11-14 | 2008-05-22 | Nippon Steel Corporation | Refractory steel material with excellent welded-joint toughness and process for producing the same |
| US8323561B2 (en) | 2006-11-14 | 2012-12-04 | Nippon Steel Corporation | Fire-resistant steel material superior in HAZ toughness of welded joint and method of production of same |
| US8715432B2 (en) | 2008-03-31 | 2014-05-06 | Nippon Steel & Sumitomo Metal Corporation | Fire-resistant steel superior in weld joint reheat embrittlement resistance and toughness and method of production of same |
| WO2021046882A1 (en) * | 2019-09-09 | 2021-03-18 | 王平 | Earthquake-resistant, fire-resistant, high-strength and high-toughness stainless structural steel and preparation method therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3371712B2 (en) | 2003-01-27 |
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