JPH0450362B2 - - Google Patents
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- Publication number
- JPH0450362B2 JPH0450362B2 JP13932889A JP13932889A JPH0450362B2 JP H0450362 B2 JPH0450362 B2 JP H0450362B2 JP 13932889 A JP13932889 A JP 13932889A JP 13932889 A JP13932889 A JP 13932889A JP H0450362 B2 JPH0450362 B2 JP H0450362B2
- Authority
- JP
- Japan
- Prior art keywords
- steel
- steel material
- construction
- temperature
- fire resistance
- 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.)
- Expired
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- 229910000831 Steel Inorganic materials 0.000 claims description 163
- 239000010959 steel Substances 0.000 claims description 163
- 239000000463 material Substances 0.000 claims description 97
- 238000010276 construction Methods 0.000 claims description 34
- 238000000034 method Methods 0.000 claims description 26
- 238000000576 coating method Methods 0.000 claims description 19
- 239000011248 coating agent Substances 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 14
- 229910052758 niobium Inorganic materials 0.000 claims description 14
- 229910052750 molybdenum Inorganic materials 0.000 claims description 12
- 230000009970 fire resistant effect Effects 0.000 claims description 10
- 238000005098 hot rolling Methods 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 238000003892 spreading Methods 0.000 claims description 5
- 230000007480 spreading Effects 0.000 claims description 5
- 239000004567 concrete Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 229910052804 chromium Inorganic materials 0.000 claims description 3
- 239000003973 paint Substances 0.000 claims description 3
- 229910052720 vanadium Inorganic materials 0.000 claims description 3
- 229910052726 zirconium Inorganic materials 0.000 claims description 3
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims 2
- 230000000694 effects Effects 0.000 description 23
- 238000005096 rolling process Methods 0.000 description 13
- 239000011490 mineral wool Substances 0.000 description 8
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- 230000007423 decrease Effects 0.000 description 6
- 230000008859 change Effects 0.000 description 5
- 229910052698 phosphorus Inorganic materials 0.000 description 5
- 229910052717 sulfur Inorganic materials 0.000 description 5
- 229910052719 titanium Inorganic materials 0.000 description 5
- 239000010953 base metal Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 239000004035 construction material Substances 0.000 description 3
- 238000009749 continuous casting Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000011160 research Methods 0.000 description 3
- 229910000532 Deoxidized steel Inorganic materials 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 230000003749 cleanliness Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000011819 refractory material Substances 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 230000002301 combined effect Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000006356 dehydrogenation reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000004079 fireproofing Methods 0.000 description 1
- 239000011491 glass wool Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000005482 strain hardening Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 230000003685 thermal hair damage Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
- Rod-Shaped Construction Members (AREA)
- Laminated Bodies (AREA)
Description
〔産業上の利用分野〕
本発明は建築、土木および海洋構造物等の分野
において、各種建造物に用いる耐火性の優れた低
降伏比鋼材の製造方法およびその鋼材によつて構
成した建築用鋼材料に関する。
〔従来の技術〕
周知の通り建築、土木および海洋構造物などの
分野における各種建造物用構築材として、一般構
造用圧延鋼材（JIS Ｇ 3101）、溶接構造用圧延
鋼材（JIS Ｇ 3106）、溶接構造用耐候性熱間圧
延鋼材（JIS Ｇ 3114）、高耐候性圧延鋼材（JIS
Ｇ 3125）および一般構造用炭素鋼鋼管（JIS Ｇ
3444）、一般構造用角形鋼管（JIS Ｇ 3466）
などが広く利用されている。
これらの鋼材は、通常高炉によつて得られた溶
銑を、脱Ｓ、脱Ｐしたのち転炉精錬を行い、連続
鋳造もしくは分塊工程において鋼片とし、ついで
熱間圧延することにより、所望の特性を備えたも
のとして製品化される。
ところで、各種建造物のうち、特に生活に密着
したビルや事務所および住居などの建造物に前記
鋼材を用いる場合は、火災における安全性を確保
するため、充分な耐火被覆を施すことが義務づけ
られており、建築関係諸法令では、火災時に鋼材
温度が350℃以上にならぬよう規定している。
つまり、前記鋼材は、建造物に使用する場合
350℃程度で耐力が常温時の60〜70％になり、建
造物の倒壊を引き起こす恐れがあるため、火災時
における熱的損傷により該鋼材が載荷力を失うこ
とのないようにして利用しなければならない。た
とえば、一般構造用圧延鋼材（JIS Ｇ 3101）に
規定される形鋼を柱材とする建造物の例では、そ
の表面にスラグウール、ロツクウール、ガラスウ
ール、アスベストなどを基材とする吹き付け材や
フエルトを展着するほか、防火モルタルで包被す
る方法および前記断熱材層の上に、さらに金属薄
板即ちアルミニウムやステンレススチール薄板等
で保護する方法など耐火被覆を入念に施す必要が
ある。
そのため、鋼材費用に比し耐火被覆施工費が高
額になり、建設コストが大幅に上昇することを避
けることが出来ない。
そこで、構築材料として丸あるいは角鋼管を用
い、冷却水が循環するように構成し、火災時にお
ける温度上昇を防止し載荷力を低下させない技術
が提案され、ビルの建設コストの引き下げと利用
空間の拡大が図られている。たとえば、実公昭52
−16021号公報には、建築物の上部に水タンクを
置き、中空鋼管からなる柱材に冷却水を供給する
耐火構造建造物が開示されている。
〔発明が解決しようとする課題〕
前述のように建造物に従来の鋼材を利用する場
合、価格は安いが、高温特性が低いため無被覆や
軽被覆で利用することが出来ず、割高な耐火被覆
を施さねばならない。このため建設コストが高く
なると共に建造物の利用空間が狭くなり、経済効
率を低下させると云う課題がある。一方耐火性能
の向上をねらいとして、中空鋼材を用いて強制冷
却する方法は、構造が複雑になるため設計、施工
費に加えて設備費が嵩むことと、保守整備費も高
額になると云う課題がある。
また、ステンレススチールに代表されるような
耐熱鋼材は価格が非常に高いため、高温特性は良
好であるが、生産技術や施工技術面に加えて経済
的な面で構築材料としての利用は非常に困難であ
る。
而して、近年建築物の高層化が進展し、設計技
術の向上とその信頼性の高さから、耐火設計につ
いて見直しが行われ、昭和62年建築物の新耐火設
計法が法定されるに至つた。その結果、前述の
350℃の温度制限によることなく、鋼材の高温強
度と建物に実際に加わつている荷重により、耐火
被覆の能力を決定出来るようになり、場合によつ
ては無被覆で鋼材を使用することも可能になつ
た。
しかしながら、耐火性の優れた建築用鋼材とし
て、経済的価格で市場に供給できるような鋼材は
現在存在しない。
本発明の目的は、高温特性が優れ、かつ経済的
価格で市場に供給しうる耐火性の優れた鋼材の製
造方法ならびに耐火性能を付与した建築用鋼材料
を提供することにある。
〔課題を解決するための手段〕
本発明は前述の課題を克服し、目的を達成する
もので、その具体的手段を下記ア〜ケ項に示す。
ア 重量比で、Ｃ 0.04〜0.15％、Si 0.6％以下、
Mn 0.5〜1.6％、Nb 0.005〜0.04％、Mo 0.4〜
0.7％、Al 0.1％以下、Ｎ 0.001〜0.006％を含
有し、残部がFeおよび不可避不純物からなる
鋼片を1100〜1300℃の温度域で再加熱後、熱間
圧延を800〜1000℃の温度範囲で終了する耐火
性の優れた建築用低降伏比鋼材の製造方法。
イ 重量比で、Ｃ 0.04〜0.15％、Si 0.6％以下、
Mn 0.5〜1.6％、Nb 0.005〜0.04％、Mo 0.4〜
0.7％、Al 0.1％以下、Ｎ 0.001〜0.006％に加
えてTi 0.005〜0.10％、Zr 0.005〜0.03％、Ｖ
0.005〜0.10％、Ni 0.05〜0.5％、Cu 0.05〜
1.0％、Cr 0.05〜1.0％、Ｂ 0.0003〜0.002％、
Ca 0.0005〜0.005％、REM 0.001〜0.02％のう
ち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鋼片を1100〜1300℃
の温度域で加熱後、熱間圧延を800〜1000℃の
温度範囲で終了する耐火性の優れた建築用低降
伏比鋼材の製造方法。
ウ 前記ア項または前記イ項記載の方法により得
られた鋼材をさらに熱間工程において塑性加工
する耐火性の優れた建築用低降伏比鋼材の製造
方法。
エ 前記ア項ないし前記ウ項記載の方法により得
られた鋼材を冷間工程において塑性加工する耐
火性の優れた建築用低降伏比鋼材の製造方法。
オ 前記ア項ないし前記エ項記載の方法により得
られた鋼材受熱表面に、無機系繊維質耐火薄層
材を展着せしめてなる耐火性の優れた建築用低
降伏比鋼材料。
カ 前記ア項ないし前記エ項記載の方法により得
られた鋼材受熱表面に、高耐熱性塗料を被着せ
しめてなる耐火性の優れた建築用低降伏比鋼材
料。
キ 前記ア項ないし前記エ項記載の方法により得
られた鋼材受熱表面に、防熱盾板を装着せしめ
てなる耐火性の優れた建築用低降伏比鋼材料。
ク 前記ア項ないし前記エ項記載の方法により得
られた中空鋼材にコンクリートを充填してなる
耐火性の優れた建築用低降伏比鋼材料。
ケ 前記ア項ないし前記エ項記載の方法により得
られた鋼材受熱表面に、極薄金属を展着してな
る耐火性の優れた建築用低降伏比鋼材料。
〔作用〕
さて、本発明者らは、火災時における鋼材強度
について研究の結果、無被覆使用を目標とした場
合、火災時の最高到達温度が1000℃であることか
ら、鋼材が該温度で常温耐力の70％以上の耐力を
備えるためには、やはり高価な合金元素を多量に
添加せねばならず、経済性を失することを知つ
た。
つまり、従来の鋼材費とそれに加え耐火被覆を
施工する費用以上に鋼材単価が高くなり、そのよ
うな鋼材は実際的に利用することが出来ない。
そこで、さらに研究を進めた結果、600℃での
高温耐力が常温時の70％（略々２／３）以上とな
る鋼材が最も経済的であることをつきとめ、高価
な添加元素の量を少なくし、かつ耐火被覆を薄く
することが可能で、火災荷重が小さい場合は、無
被覆で使用することが出来る鋼材の製造方法に加
えて耐火性能を付与した鋼材料を開発した。
さて、本発明の特徴は、低Ｃ−低Mn鋼に微量
Nbと適当量のMoを複合添加した成分組成の鋼片
を、高温で再加熱したのち、比較的高温で圧延を
終了することにあり、本発明によつて得られた鋼
材は、適当な常温耐力を有するとともに、高温耐
力が高いと云う特性を備えている。
つまり、常温耐力に対し600℃の温度域におけ
る耐力の割合が大きい。この理由はミクロ組織が
比較的大きなフエライト主体組織となつているた
めで、これに対し、細粒フエライトや焼入、焼戻
主体組織などでは、600℃の温度領域における耐
力に比して常温耐力が高くなり、常温での規格値
を満足させることは難かしい。
本発明にかかる鋼材は降伏比が低く、耐震性に
優れているが、これもミクロ組織が比較的大きな
フエライトからなるためである。
つぎに、本発明にかかる特徴的な成分元素とそ
の添加量について説明する。
Nb，Moは微細な炭窒化物を形成し、さらに、
Moは固溶体強化によつて高温強度を増加させる
が、Moの単独添加では600℃という高温領域に
おいて充分な耐力を得ることは難しい。
本発明者等は研究の結果、該高温領域における
耐力を増加させるには、NbとMoを複合添加させ
ることが極めて有効なことを見出した。
しかしながらNb，Mo量が高すぎると、溶接性
が悪くなり、さらに溶接熱影響部（HAZ）の靭
性が劣化するので、Nb，Mo含有量の上限はそれ
ぞれ0.04％、0.7％とする必要があり、また下限
は複合効果が得られる最小量としてそれぞれ
0.005％、0.4％を含有せしめる。
なお、高温強度を上昇せしめるため、Moを利
用することは、従来の耐熱鋼では知られている
が、建築用に用いる耐火鋼材として前述のように
微量のMoに加えて微量のNbを複合添加した鋼材
は知られていない。
もつとも、NbとMoを複合添加した鋼材とし
て、ラインパイプ用のアシキユラーフエライト鋼
が知られているが、該アシキユラーフエライト鋼
は製造にあたり、その目的を達成するため、強度
の制御圧延を行い、常温耐力を高めているため常
温の降伏比が高くなり、建築用鋼材として必要な
低降伏比を満足出来ない。
さらにつけ加えると、前記アシキユラーフエラ
イト鋼は本発明鋼に比してMn含有量が多い。こ
れは本発明鋼とは異なり低温靭性を高めることが
重要なためで、両者は目的および作用効果の点で
顕著な差異がある。
つぎに、本発明における前記Nb，Mo以外の成
分限定理由について詳細に説明する。
Ｃは母材および溶接部の強度確保ならびにNb，
Moの添加効果を発揮させるために必要であり、
0.04％以下では効果が薄れるので下限は0.04％と
する。さらにＣ量が多すぎるとHAZの低温靭性
を悪影響をおよぼすだけでなく、母材靭性、溶接
性をも劣化させるので、0.15％が上限となる。
Siは脱酸上鋼に含まれる元素で、Siが多くなる
と溶接性、HAZ靭性が劣化するため、その上限
を0.6％とした。本発明鋼ではAl脱酸で充分であ
り、さらにTi脱酸でも良い。SiはHAZ靭性の点
からは含有量を0.15％程度とすることが望まし
い。
次に、Mnは強度、靭性を確保する上で下可欠
な元素であり、その下限は0.5％である。しかし
Mn量が多すぎると焼入性が増加して溶接性、
HAZ靭性が劣化するだけでなく、目標とする規
格に適合する母材強度を得ることが出来ない。こ
のためMn量の上限を1.6％とした。
Alは一般に脱酸上鋼に含まれる元素であるが、
SiおよびTiによつても脱酸は行なわれるので、
本発明ではAlについて下限は限定しない。しか
しAl量が多くなると鋼の清浄度が悪くなり、溶
接部の靭性が劣化するので上限を0.1％とした。
Ｎは一般に不可避的不純物として鋼中に含まれ
るものであるが、Nbと結合し炭窒化物Nb（CN）
を形成して高温耐力の向上に効果を発揮する。こ
のため最小量として0.001％必要であるが、Ｎ量
が多くなるとHAZ靭性の劣化や連続鋳造スラブ
の表面疵の発生などを助長するので、その上限を
0.006％とした。
なお、本発明鋼材は、不可避不純物としてＰお
よびＳを含有する。Ｐ，Ｓは高温強度に与える影
響は小さいので、その量について特に限定はしな
いが、一般に靭性、板厚方向強度などに関する鋼
材の特性は、Ｐ，Ｓ量が少ないほど向上する。望
ましいＰ，Ｓ量はそれぞれ0.02％、0.005％以下
である。
本発明鋼材の基本成分は以上のとおりであり、
充分に目的を達成できるが、さらに以下に述べる
元素即ちTi，Zr，Ｖ，Ni，Cu，Cr，Ｂ，Ca，
REMを選択的に添加すると強度、靭性の向上に
ついて、さらに好ましい結果が得られる。
つぎに、前記添加元素とその添加量について説
明する。
Tiは前述のNbとほぼ同じ効果を持つ元素であ
り、0.005〜0.02％においてAl量が少ない場合Ti
の酸化物、炭窒化物を形成し、HAZ靭性を向上
させるが、0.005％以下では効果がなく、0.1％を
超えると溶接性などに悪影響がでて好ましくな
い。
ＶもNb，Tiとほぼ同じ効果をもつ元素であ
り、高温耐力に対する効果はNb，Tiに比較して
小さいが0.005〜0.10％の範囲においてHAZ靭性
を向上させる。しかし、0.005％以下では効果が
無く0.10％を超えるとHAZ靭性に好ましくない
影響がある。
つぎに、Niは溶接性、HAZ靭性に悪影響をお
よぼすことなく、母材の強度、靭性を向上させる
が、0.05％以下では効果が薄く、0.5％以上の添
加は建築用鋼材として、極めて高価になるため経
済性を失うので、上限は0.5％とした。
CuはNiとほぼ同様な効果を持つほか、Cu析出
物による高温強度の増加や耐食性、耐候性の向上
にも効果を有する。しかし、Cu量が1.0％を超え
ると熱間圧延時にCu割れが発生し製造が困難に
なり、また0.05％以下では効果が無いのでCu量は
0.05〜1.0％に限定する。
Crは母材および溶接部の強度を高める元素で
あり、耐候性の向上にも効果はあるが、1.0％を
超えると溶接性やHAZ靭性を劣化させ、また
0.05％以下では効果が薄い。従つてCr量は0.05〜
1.0％とする。
本発明者等の知見ではCrはMoと同様に高温耐
力を増加させる元素であるが、Moと異なり常温
耐力の増加の割に比し、600℃での高温耐力の増
加効果は比較的少ない。
Ｂは鋼の焼入性を増大させ強度を大きくする元
素であり、Ｎと結合したBNはフエライト発生核
として作用し、HAZ組織を微細化する。このよ
うなＢの効果を得るためには、最小限0.0003％の
Ｂ量が必要で、それ以下では効果が無く、またＢ
量が多過ぎると粗大なＢ−constituentが、HAZ
の旧オーステナイト粒界に析出して低温靭性を劣
化させる。このためＢ量の上限は0.002％に制限
する。
Ca，REMは硫化物（MnS）の形態を制御し、
シヤルピー吸収エネルギーを増加させ低温靭性を
向上させるほか、耐水素誘起割れ性の改善にも効
果を発揮する。しかしCa量は0.0005％以下では実
用上効果が無く、また、0.005％を超えるとCaO，
CaSが多量に生成して大形介在物となり、鋼の靭
性のみならず清浄度も害し、さらに溶接性にも悪
影響を与えるので、Ca添加量の範囲を0.0005〜
0.005％とする。
また、REMについてもCaと同様な効果があ
り、また添加量を多くするとCaと同様な問題が
生じ、また経済性も悪くなるので、REM量の下
限を0.001％とし上限を0.02％とする。
次に、本発明に係る鋼材の製造方法について説
明する。
常温において、溶接構造用圧延鋼材（JIS Ｇ
3106）に規定する性能を満足し、かつ600℃の高
温において高い耐力を維持せしめるためには、鋼
材成分と共に鋼材の加熱および圧延にかかる条件
が重要である。本発明の鋼材成分の特徴をなす
Nb，Moの複合添加による高温耐力の増大を図る
には、加熱時に、これらの元素を充分に溶体化さ
せる必要があり、このため本発明の成分よりなる
鋼片の加熱温度の下限を1100℃とする。また、加
熱温度が高すぎると結晶粒が大きくなつて低温靭
性が劣化するので、その上限は1300℃にせねばな
らない。
次に、加熱した鋼片を熱間圧延するが、その圧
延終了温度を800℃以上の高温とする。その理由
は、圧延中にNb，Moの炭窒化物を析出させない
ためであり、γ域で、これらの元素が析出する
と、析出物サイズが大きくなり、高温耐力が著し
く低下する。
従来低温圧延（制御圧延）はラインパイプなど
低温靭性が必要な鋼材では必須要件であるが、本
発明鋼のように低温靭性について、高い要求が無
く、むしろ常温耐力と600℃での高温耐力のバラ
ンスが重要な場合には、圧延を高温で終了せねば
ならない。これは降伏比の低減条件としても重要
である。また、本発明において、圧延終了温度の
上限を1000℃とするが、その理由は、建築用鋼と
しての靭性を確保するためである。熱間圧延終了
後は室温迄放冷する。
なお、本発明鋼材を製造後、脱水素などの目的
でAc1変態点以下の温度に再加熱しても、本発明
鋼材の特徴は何等損なわれることは無い。
また、本発明では、前述のように鋼片を加熱
し、ついで熱間圧延することにより製品とする
が、その後さらに所望の鋼材を製造するため、前
記製品を熱間又は冷間でさらに塑性加工してもよ
い。
たとえば、鋼片をブルーム、ビレツトとしたの
ち熱間で形鋼とするほか、前記製品を素材とし、
冷間加工して所望の鋼材たとえば形鋼や鋼管を製
造しても良い。その際、必要に応じて、熱処理を
適宜に実施する。
さて、次に本発明鋼材の機械的性質を周知鋼材
と比較して詳細に説明する。
第１表は本発明鋼材とJIS Ｇ 3106溶接構造用
圧延鋼材（SM50A）との成分比較を示る。
なお、本発明の鋼材は上記表に示す成分の鋼片
を1200℃に加熱し、圧延終了温度950℃熱間圧延
し、圧延終了後室温迄放冷して製造された。
[Industrial Field of Application] The present invention is applicable to the fields of architecture, civil engineering, marine structures, etc., and to a method for manufacturing a low yield ratio steel material with excellent fire resistance for use in various buildings, and to a construction steel constructed from the steel material. Regarding materials. [Prior art] As is well known, rolled steel for general structures (JIS G 3101), rolled steel for welded structures (JIS G 3106), and welded steel are used as construction materials for various buildings in the fields of architecture, civil engineering, and marine structures. Structural weather resistant hot rolled steel materials (JIS G 3114), high weather resistant rolled steel materials (JIS G 3114)
G 3125) and general structural carbon steel pipes (JIS G
3444), square steel pipes for general structures (JIS G 3466)
etc. are widely used. These steel materials are usually produced by removing S and P from hot metal obtained in a blast furnace, then refining it in a converter furnace, turning it into steel billets in a continuous casting or blooming process, and then hot rolling them into the desired shape. It is commercialized as something with special characteristics. By the way, when the above-mentioned steel materials are used for various buildings, especially those that are closely connected to daily life, such as buildings, offices, and residences, it is mandatory to apply sufficient fireproof coating to ensure safety in the event of a fire. Building laws and regulations stipulate that the temperature of steel materials should not exceed 350℃ in the event of a fire. In other words, when the steel material is used in buildings,
At around 350℃, the yield strength decreases to 60 to 70% of that at room temperature, which could cause the structure to collapse, so the steel must be used in a way that prevents it from losing its load-bearing capacity due to thermal damage in the event of a fire. Must be. For example, in the case of a building whose columns are made of section steel stipulated by general structural rolled steel materials (JIS G 3101), the surface may be coated with sprayed materials based on slag wool, rock wool, glass wool, asbestos, etc. In addition to spreading felt, it is necessary to carefully apply a fireproof coating, such as enveloping it with fireproof mortar or protecting it with a thin metal plate, such as an aluminum or stainless steel plate, on top of the heat insulating layer. Therefore, the construction cost of fireproof coating becomes high compared to the cost of steel materials, and it is impossible to avoid a significant increase in construction cost. Therefore, a technology has been proposed in which round or square steel pipes are used as construction materials to allow cooling water to circulate, preventing temperature rise in the event of a fire and reducing loading capacity. Expansion is being planned. For example, Jikko 52
Publication No. -16021 discloses a fireproof structure building in which a water tank is placed on the top of the building and cooling water is supplied to pillars made of hollow steel pipes. [Problems to be solved by the invention] As mentioned above, when conventional steel materials are used in buildings, the price is low, but due to their low high-temperature properties, they cannot be used uncoated or lightly coated, and they require relatively expensive fire resistance. Must be covered. Therefore, there are problems in that the construction cost increases and the usable space of the building becomes narrower, reducing economic efficiency. On the other hand, the method of forced cooling using hollow steel materials with the aim of improving fire resistance has the problem of a complicated structure, which increases equipment costs in addition to design and construction costs, and high maintenance costs. be. In addition, heat-resistant steel materials such as stainless steel are very expensive, and although they have good high-temperature properties, their use as construction materials is extremely difficult due to production and construction technology as well as economic aspects. Have difficulty. In recent years, as buildings have become taller, fire-resistant design has been reviewed due to improvements in design technology and its reliability, and in 1988, a new fire-resistant design law for buildings was enacted. I've reached it. As a result, the aforementioned
The ability of fireproof coating can now be determined based on the high-temperature strength of the steel material and the load actually applied to the building, without being subject to the 350℃ temperature limit, and in some cases it is also possible to use steel without coating. It became. However, there is currently no steel material that can be supplied to the market at an economical price as a structural steel material with excellent fire resistance. An object of the present invention is to provide a method for producing a steel material with excellent high-temperature properties and excellent fire resistance that can be supplied to the market at an economical price, as well as a steel material for construction with fire resistance. [Means for Solving the Problems] The present invention overcomes the above-mentioned problems and achieves the objects, and specific means thereof are shown in the following sections. A. In terms of weight ratio, C 0.04 to 0.15%, Si 0.6% or less,
Mn 0.5~1.6%, Nb 0.005~0.04%, Mo 0.4~
After reheating a steel billet containing 0.7% Al, 0.1% or less Al, and 0.001-0.006% N, with the balance consisting of Fe and unavoidable impurities in a temperature range of 1100-1300°C, hot rolling was performed at a temperature of 800-1000°C. A method for producing low yield ratio steel for construction with excellent fire resistance ending in the range. (a) In terms of weight ratio, C 0.04 to 0.15%, Si 0.6% or less,
Mn 0.5~1.6%, Nb 0.005~0.04%, Mo 0.4~
0.7%, Al 0.1% or less, N 0.001-0.006% plus Ti 0.005-0.10%, Zr 0.005-0.03%, V
0.005~0.10%, Ni 0.05~0.5%, Cu 0.05~
1.0%, Cr 0.05~1.0%, B 0.0003~0.002%,
A steel billet containing one or more of Ca 0.0005~0.005% and REM 0.001~0.02%, with the balance consisting of Fe and unavoidable impurities, was heated to 1100~1300℃.
A method for producing low yield ratio steel materials for construction with excellent fire resistance, which involves heating in a temperature range of 800 to 1000 degrees Celsius and then finishing hot rolling in a temperature range of 800 to 1000 degrees Celsius. C. A method for producing a low yield ratio steel material for construction with excellent fire resistance, which further comprises plastic working the steel material obtained by the method described in the above item A or the above item A in a hot process. D. A method for producing a low yield ratio steel material for construction with excellent fire resistance, which comprises plastically working the steel material obtained by the method described in the above items A to C in a cold process. E. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by spreading an inorganic fibrous fire-resistant thin layer material on the heat-receiving surface of the steel material obtained by the method described in the above-mentioned items A to D. F. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by coating the heat-receiving surface of the steel material obtained by the method described in the above-mentioned items A to D above with a highly heat-resistant paint. G. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by attaching a heat shield plate to the heat-receiving surface of the steel material obtained by the method described in items A to D above. (h) A low yield ratio steel material for construction with excellent fire resistance, which is obtained by filling concrete into a hollow steel material obtained by the method described in items A to D above. (k) A low yield ratio steel material for construction with excellent fire resistance, which is obtained by spreading an ultra-thin metal onto the heat-receiving surface of the steel material obtained by the method described in items A to D above. [Function] As a result of research on the strength of steel materials in the event of a fire, the inventors of the present invention found that when uncoated use is targeted, the maximum temperature reached in the event of a fire is 1000°C. We learned that in order to provide a yield strength of 70% or more, a large amount of expensive alloying elements must be added, which would be uneconomical. In other words, the unit price of the steel material becomes higher than the cost of the conventional steel material and the cost of installing a fireproof coating in addition to the cost of the conventional steel material, and such steel material cannot be practically used. Therefore, as a result of further research, we found that the most economical steel material had a high-temperature yield strength of 70% (approximately 2/3) of that at room temperature at 600°C, and reduced the amount of expensive additive elements. In addition to a manufacturing method that allows the fire-resistant coating to be made thinner and can be used without coating when the fire load is small, we have also developed a steel material that has fire-resistant properties. Now, the feature of the present invention is that a trace amount is added to low C-low Mn steel.
After reheating a steel billet with a composition in which Nb and an appropriate amount of Mo are added together at a high temperature, rolling is completed at a relatively high temperature. It has properties such as high yield strength and high high temperature yield strength. In other words, the ratio of proof stress in the temperature range of 600°C to normal temperature proof stress is large. The reason for this is that the microstructure is a relatively large ferrite-based structure, whereas fine-grained ferrite, quenched, and tempered structures have a room-temperature yield strength that is higher than that in the 600°C temperature range. becomes high, making it difficult to satisfy standard values at room temperature. The steel material according to the present invention has a low yield ratio and excellent seismic resistance, and this is also because the microstructure is composed of relatively large ferrite. Next, characteristic component elements according to the present invention and their addition amounts will be explained. Nb and Mo form fine carbonitrides, and
Mo increases high-temperature strength through solid solution strengthening, but it is difficult to obtain sufficient yield strength in the high-temperature range of 600°C by adding Mo alone. As a result of research, the present inventors have found that adding Nb and Mo in combination is extremely effective in increasing the yield strength in the high temperature range. However, if the Nb and Mo contents are too high, weldability will deteriorate and the toughness of the weld heat affected zone (HAZ) will deteriorate, so the upper limits of the Nb and Mo contents need to be 0.04% and 0.7%, respectively. , and the lower limit is the minimum amount to obtain the combined effect, respectively.
Contains 0.005% and 0.4%. The use of Mo in order to increase high-temperature strength is known in conventional heat-resistant steels, but as mentioned above, in addition to a small amount of Mo, a small amount of Nb is added in combination for fire-resistant steel materials used for construction. There are no known steel materials. Of course, axial ferrite steel for line pipes is known as a steel material with a composite addition of Nb and Mo, but in order to achieve its purpose, axial ferrite steel is produced by controlled rolling for strength. As the yield strength at room temperature is increased, the yield ratio at room temperature becomes high, and the low yield ratio required for construction steel cannot be met. In addition, the above-mentioned axial ferrite steel has a higher Mn content than the steel of the present invention. This is because, unlike the steel of the present invention, it is important to improve low-temperature toughness, and there are significant differences between the two in terms of purpose and function and effect. Next, the reason for limiting components other than Nb and Mo in the present invention will be explained in detail. C is for ensuring the strength of the base metal and welded part, and Nb,
It is necessary to exhibit the effect of Mo addition,
If it is less than 0.04%, the effect will be weakened, so the lower limit is set at 0.04%. Furthermore, if the amount of C is too large, it not only adversely affects the low-temperature toughness of the HAZ, but also deteriorates the toughness and weldability of the base metal, so 0.15% is the upper limit. Si is an element contained in deoxidized steel, and as Si increases, weldability and HAZ toughness deteriorate, so the upper limit was set at 0.6%. In the steel of the present invention, Al deoxidation is sufficient, and Ti deoxidation may also be used. From the viewpoint of HAZ toughness, it is desirable that the content of Si be approximately 0.15%. Next, Mn is an essential element for ensuring strength and toughness, and its lower limit is 0.5%. but
If the amount of Mn is too large, the hardenability will increase and the weldability will deteriorate.
Not only does HAZ toughness deteriorate, but the base material strength that meets the target standards cannot be obtained. For this reason, the upper limit of the Mn content was set at 1.6%. Al is an element generally included in deoxidized steel,
Deoxidation is also carried out by Si and Ti, so
In the present invention, there is no lower limit for Al. However, if the amount of Al increases, the cleanliness of the steel will deteriorate and the toughness of the weld will deteriorate, so the upper limit was set at 0.1%. N is generally contained in steel as an unavoidable impurity, but it combines with Nb to form carbonitride Nb (CN).
, which is effective in improving high-temperature yield strength. For this reason, a minimum amount of 0.001% is required, but if the amount of N increases, it promotes deterioration of HAZ toughness and surface flaws in continuous casting slabs, so the upper limit should be set.
It was set at 0.006%. Note that the steel material of the present invention contains P and S as inevitable impurities. Since P and S have a small effect on high-temperature strength, their amounts are not particularly limited, but generally the properties of steel materials, such as toughness and strength in the thickness direction, improve as the amounts of P and S decrease. Desirable amounts of P and S are 0.02% and 0.005% or less, respectively. The basic components of the steel material of the present invention are as described above,
Although the purpose can be fully achieved, the following elements such as Ti, Zr, V, Ni, Cu, Cr, B, Ca,
When REM is selectively added, more favorable results can be obtained in terms of improving strength and toughness. Next, the additive elements and their amounts will be explained. Ti is an element that has almost the same effect as Nb mentioned above, and when the amount of Al is small at 0.005 to 0.02%, Ti
It forms oxides and carbonitrides and improves HAZ toughness, but if it is less than 0.005%, it has no effect, and if it exceeds 0.1%, it has an adverse effect on weldability, etc., which is not desirable. V is also an element that has almost the same effect as Nb and Ti, and although its effect on high-temperature yield strength is smaller than that of Nb and Ti, it improves HAZ toughness in the range of 0.005 to 0.10%. However, if it is less than 0.005%, it has no effect, and if it exceeds 0.10%, it has an unfavorable effect on HAZ toughness. Next, Ni improves the strength and toughness of the base metal without adversely affecting weldability and HAZ toughness, but if it is less than 0.05%, the effect is weak, and if it is added more than 0.5%, it becomes extremely expensive for construction steel. The upper limit was set at 0.5%, as this would lead to a loss of economic efficiency. In addition to having almost the same effects as Ni, Cu also has the effect of increasing high-temperature strength and improving corrosion resistance and weather resistance due to Cu precipitates. However, if the Cu amount exceeds 1.0%, Cu cracking occurs during hot rolling, making manufacturing difficult, and if it is less than 0.05%, there is no effect, so the Cu amount is
Limited to 0.05-1.0%. Cr is an element that increases the strength of the base metal and welded parts, and is effective in improving weather resistance, but if it exceeds 1.0%, it deteriorates weldability and HAZ toughness, and
The effect is weak below 0.05%. Therefore, the amount of Cr is 0.05~
It shall be 1.0%. According to the findings of the present inventors, Cr is an element that increases high-temperature yield strength like Mo, but unlike Mo, the effect of increasing high-temperature yield strength at 600°C is relatively small compared to the increase in room-temperature yield strength. B is an element that increases the hardenability and strength of steel, and BN combined with N acts as a ferrite generation nucleus and refines the HAZ structure. In order to obtain this effect of B, a minimum amount of B of 0.0003% is required; anything less than that has no effect, and B
If the amount is too large, the coarse B-constituent will become HAZ
precipitates at prior austenite grain boundaries and deteriorates low-temperature toughness. Therefore, the upper limit of the amount of B is limited to 0.002%. Ca, REM controls the morphology of sulfide (MnS),
In addition to increasing the Charpy absorbed energy and improving low-temperature toughness, it is also effective in improving hydrogen-induced cracking resistance. However, if the amount of Ca is less than 0.0005%, it has no practical effect, and if it exceeds 0.005%, CaO,
A large amount of CaS is generated and becomes large inclusions, which impairs not only the toughness but also the cleanliness of the steel, and also has a negative effect on weldability.
It shall be 0.005%. Further, REM has the same effect as Ca, and if the amount added is increased, the same problems as Ca occur, and the economy is also poor, so the lower limit of the amount of REM is set to 0.001% and the upper limit is set to 0.02%. Next, a method for manufacturing steel materials according to the present invention will be explained. At room temperature, rolled steel for welded structures (JIS G
In order to satisfy the performance specified in 3106) and maintain high yield strength at a high temperature of 600°C, the conditions for heating and rolling the steel are important as well as the steel composition. Characteristics of the steel composition of the present invention
In order to increase the high-temperature yield strength through the combined addition of Nb and Mo, it is necessary to sufficiently dissolve these elements during heating. For this reason, the lower limit of the heating temperature for steel slabs made of the ingredients of the present invention is set at 1100°C. shall be. Furthermore, if the heating temperature is too high, the crystal grains will become large and the low temperature toughness will deteriorate, so the upper limit must be set at 1300°C. Next, the heated steel billet is hot rolled, and the rolling end temperature is set to a high temperature of 800°C or higher. The reason for this is to prevent carbonitrides of Nb and Mo from precipitating during rolling. If these elements precipitate in the γ region, the precipitate size increases and the high temperature yield strength significantly decreases. Conventional low-temperature rolling (controlled rolling) is an essential requirement for steel materials that require low-temperature toughness such as line pipes, but there is no high requirement for low-temperature toughness like the steel of the present invention, and rather it is necessary to improve the yield strength at room temperature and high temperature yield strength at 600℃. If balance is important, rolling must be finished hot. This is also important as a condition for reducing the yield ratio. Further, in the present invention, the upper limit of the rolling end temperature is set to 1000° C., and the reason for this is to ensure toughness as a construction steel. After hot rolling, it is allowed to cool to room temperature. Note that even if the steel of the present invention is reheated to a temperature below the Ac 1 transformation point for the purpose of dehydrogenation or the like after production, the characteristics of the steel of the present invention will not be impaired in any way. Furthermore, in the present invention, the steel billet is heated and then hot-rolled to produce a product as described above, and after that, in order to further manufacture a desired steel material, the product is further subjected to hot or cold plastic processing. You may. For example, in addition to turning a steel billet into a bloom or billet and then hot forming it into a section steel,
A desired steel material, such as a section steel or a steel pipe, may be produced by cold working. At that time, heat treatment is appropriately performed as necessary. Next, the mechanical properties of the steel material of the present invention will be explained in detail in comparison with known steel materials. Table 1 shows a compositional comparison between the steel material of the present invention and JIS G 3106 rolled steel material for welded structures (SM50A). The steel material of the present invention was produced by heating a steel slab having the components shown in the above table to 1200°C, hot rolling it at a rolling finish temperature of 950°C, and allowing it to cool to room temperature after rolling.
【表】
第１図は、縦軸に応力度（Kgｆ／mm2）、横軸に
温度（℃）をとつたもので、実線で示す折線１が
本発明鋼材、破線で示す折線２が比較鋼材
（SM50A）の変化を示す。なお、TSは引張強さ、
YPは降伏点を示す。
第１図から明らかなように、800℃を超える温
度では、差がなくなるが、本発明鋼材は600℃〜
700℃においてSM50Aの２倍の耐力を保持してお
り、建築用鋼材として優れた特性を備えているこ
とが判る。
第２図は、縦軸に弾性係数（Kgｆ／mm2）、横軸
に温度（℃）をとつたもので、実線で示す折線１
が本発明鋼材、破線で示す折線２がSM50Aの変
化を示す。また、第３図は、縦軸にクリープ歪
（％）、横軸に時間（分）をとり、試験片に加わる
600℃における応力度（Kgｆ／mm2）をパラメータ
ーとしており本発明鋼材の変化を折線で示し、第
４図は、同様にSM50Aの変化を折線で示してい
る。
第２図から明らかなように、本発明鋼材は、
700℃を超える温度で弾性係数が急激に低下する
のに対して、SM50Aは、600℃近辺で弾性係数が
急激に低下している。また、第３図および第４図
から明らかなように、本発明鋼材は、600℃の温
度で通常建物の柱・はりなど構造部材に作用する
応力度15Kgｆ／mm2に対し、通常の火災の最大継続
時間である３時間においてもクリープ歪の進行は
著しく少ないが、SM50Aは、600℃の温度で応力
度10Kgｆ／mm2が加わるとクリープ歪の進行が著し
く大きい。弾性係数が高温まで低下しないこと、
クリープ歪の進行が少ないことは、火災時に建物
の変形を少なくするため、本発明鋼材は、
SM50Aと比較して、建築用鋼材として優れた特
性を備えていることが判る。
本発明者らは、比較鋼材SS41との比較におい
ても同様な結果を得た。
このことから、本発明鋼材は、SM50AやSS41
に比し火災荷重が等しい場合、耐火被覆がより薄
いものでよいことが明らかであり、火災荷重が大
きくないときには、無被覆で済むことも、また明
らかである。
つぎに、本発明鋼材に無機系繊維質耐火薄層材
を展着した例について説明する。
第２表は耐火被覆厚さに関する実施例で、JIS
Ｇ 1304で規定される実験において、鋼材温度が
350℃を超えないようにするため、必要な耐火材
別の被覆厚さを示す。
ところで、本発明鋼材の場合は、600℃を超え
るまで鋼材温度が上昇しても良いので、前述のと
おりその耐火被覆の厚さは第３表のように薄くて
済む。
第２表、第３表の比較から明らかなように本発
明鋼材を利用する場合、耐火被覆の材料費、施工
費が大幅に軽減できる。[Table] In Figure 1, the vertical axis shows the stress (Kgf/mm 2 ) and the horizontal axis shows the temperature (°C). The solid line 1 shows the steel of the present invention, and the broken line 2 shows the comparison. Shows changes in steel material (SM50A). In addition, TS is tensile strength,
YP indicates yield point. As is clear from Fig. 1, the difference disappears at temperatures exceeding 800°C, but the steel of the present invention
It maintains twice the yield strength of SM50A at 700℃, indicating that it has excellent properties as a building steel material. Figure 2 shows the elastic modulus (Kgf/mm 2 ) on the vertical axis and the temperature (℃) on the horizontal axis.
is the steel material of the present invention, and the broken line 2 shows the change in SM50A. In addition, Figure 3 shows the creep strain (%) on the vertical axis and the time (minutes) on the horizontal axis, and shows the creep strain (%) applied to the test piece.
The stress degree (Kgf/mm 2 ) at 600° C. is used as a parameter, and the change in the steel material of the present invention is shown by a broken line, and FIG. 4 similarly shows the change in SM50A by a broken line. As is clear from FIG. 2, the steel material of the present invention is
The elastic modulus of SM50A rapidly decreases at temperatures above 700°C, whereas the elastic modulus of SM50A rapidly decreases at temperatures around 600°C. Furthermore, as is clear from Figures 3 and 4, the steel of the present invention has a stress level of 15 kgf/mm 2 that acts on structural members such as pillars and beams of ordinary buildings at a temperature of 600°C, compared to that of a normal fire. Even at the maximum duration of 3 hours, the progress of creep strain is extremely small, but when a stress level of 10 Kgf/mm 2 is applied to SM50A at a temperature of 600°C, the progress of creep strain is extremely large. The elastic modulus does not decrease at high temperatures,
The less progression of creep strain reduces the deformation of the building in the event of a fire, so the steel of the present invention
Compared to SM50A, it can be seen that it has superior properties as a construction steel material. The present inventors obtained similar results in comparison with comparative steel material SS41. From this, the steel materials of the present invention are suitable for SM50A and SS41.
When the fire load is the same, it is clear that the fireproof coating can be thinner, and it is also clear that when the fire load is not large, no coating can be used. Next, an example in which an inorganic fibrous refractory thin layer material is spread on the steel material of the present invention will be described. Table 2 is an example regarding the thickness of fireproof coating, JIS
In the experiments specified in G 1304, the steel temperature was
Indicates the required coating thickness for each type of refractory material in order to prevent temperatures from exceeding 350℃. By the way, in the case of the steel material of the present invention, the temperature of the steel material may rise to over 600°C, so as mentioned above, the thickness of the fireproof coating can be as thin as shown in Table 3. As is clear from the comparison of Tables 2 and 3, when the steel of the present invention is used, the material cost and construction cost of fireproof coating can be significantly reduced.
【表】【table】
【表】【table】
【表】
つぎに、第５図は本発明にかかるＨ形鋼１
（300×300×10×15）に第３表における吹き付け
ロツクウール（湿式）２を展着した柱の概略立面
図およびＡ−Ａ断面図である。
第６図は、前記Ｈ形鋼柱に、JIS Ａ 1304で規
定される加熱を行い、通常建物の柱が支持する荷
重を加えて、破壊する時間を求めた試験結果であ
り、縦軸に温度（℃）、横軸に時間（分）をとつ
たもので、実線で示す折線１は柱の鋼材温度、破
線で示す折線２は加熱温度の変化を示す。また、
第７図は、縦軸に変形（cm）、横軸に温度（℃）
及び時間（分）をとつたもので、実線で示す折線
は柱の変形を示す。第６図および第７図から明ら
かなように、10mmの厚さの吹き付けロツクウール
（湿式）を施すことで、本発明鋼材で製造した柱
は600℃を超えるまで破壊を起こさず、１時間耐
火以上の性能を発揮していることが判る。
同様に、第８図は、本発明にかかるＨ形鋼はり
３（400×200×８×13）に、第３表における吹き
付けロツクウール（湿式）４を展着したはりの概
略立面図およびＡ−Ａ断面図である。
第９図は、前記Ｈ形鋼はりに、（JIS Ａ 1304
で規定される加熱を行い、通常建物のはりが支持
する荷重を加えて、破壊する時間を求めた試験結
果であり、縦軸に温度（℃）、横軸に時間（分）
をとつたもので、実線で示す折線１ははり上側フ
ランジ５、折線２ははり下側フランジ６、折線３
はウエブ７の各温度を、破線で示す折線４は加熱
温度の変化を示す。また、第１０図は、縦軸に変
形（鉛直たわみ）（cm）、横軸に温度（℃）及び時
間（分）をとつたもので、実線で示す折線は、は
り各点の変形を示す。第８図および第９図から明
らかなように、10mmの厚さの吹き付けロツクウー
ル（湿式）施すことで、本発明鋼材で製造したは
りは、600℃を超えるまで破壊を起こさず、１時
間耐火以上の性能を発揮していることが判る。
又、600℃における変形量も変形許容値以下であ
ることが判る。
本発明者らは、他の耐火材についても試験を行
つたが同様な結果を得た。
つぎに、本発明鋼材について高耐熱性塗料を被
着し、試験した結果を第４表に示す。[Table] Next, FIG. 5 shows the H-section steel 1 according to the present invention.
They are a schematic elevational view and an AA sectional view of a column (300 x 300 x 10 x 15) on which sprayed rock wool (wet type) 2 in Table 3 is spread. Figure 6 shows the test results of heating the H-shaped steel column specified in JIS A 1304, applying a load normally supported by building columns, and determining the time to failure.The vertical axis shows the temperature. (°C), and time (minutes) is plotted on the horizontal axis, where the solid line 1 shows the steel temperature of the column, and the broken line 2 shows the change in heating temperature. Also,
Figure 7 shows deformation (cm) on the vertical axis and temperature (℃) on the horizontal axis.
and time (minutes), and the solid broken line indicates the deformation of the column. As is clear from Figures 6 and 7, by applying 10 mm thick sprayed rock wool (wet process), the columns made of the steel of the present invention do not break even at temperatures exceeding 600°C, and are fire resistant for more than 1 hour. It can be seen that the performance is demonstrated. Similarly, FIG. 8 is a schematic elevational view of an H-shaped steel beam 3 (400 x 200 x 8 x 13) according to the present invention and a beam in which sprayed rock wool (wet type) 4 in Table 3 is spread. -A sectional view. Figure 9 shows the H-shaped steel beam (JIS A 1304
The results are the test results obtained by heating according to the standards specified in the above table, applying the load normally supported by building beams, and determining the time to failure.The vertical axis shows temperature (℃) and the horizontal axis shows time (minutes).
The solid line 1 is the upper flange of the beam 5, the 2nd line is the lower flange 6 of the beam, and the 3rd line is the lower flange of the beam.
indicates each temperature of the web 7, and a broken line 4 indicates a change in heating temperature. In addition, in Figure 10, the vertical axis shows deformation (vertical deflection) (cm), and the horizontal axis shows temperature (°C) and time (minutes), and the solid broken line shows the deformation at each point of the beam. . As is clear from Figures 8 and 9, by applying sprayed rock wool (wet process) to a thickness of 10 mm, the beam made of the steel of the present invention does not break even at temperatures exceeding 600°C, and is fire resistant for more than 1 hour. It can be seen that the performance is demonstrated.
It is also seen that the amount of deformation at 600°C is less than the allowable deformation value. The present inventors also conducted tests on other refractory materials and obtained similar results. Next, the steel materials of the present invention were coated with a highly heat-resistant paint and tested, and the results are shown in Table 4.
周知の転炉、連続鋳造、圧延工程で種々の鋼材
成分の鋼材を製造し、常温耐力（降伏強度）、高
温耐力（降伏強度）などを調査した。
第５表、第６表、第７表に本発明鋼材と比較鋼
材との成分比較を示し、続いて第８表〜第12表に
加熱、圧延、冷却条件別に機械的特性を示す。
第８表〜第12表で明らかなように本発明例が、
すべて良好な常温および高温耐力を有するのに対
し、比較例はことごとく、常温での耐力が高すぎ
たり、あるいは高温耐力が不足し、さらに常温耐
力に対する600℃での耐力割合が低く、耐火建築
材として不適である。
Steel materials with various steel components were manufactured using well-known converter, continuous casting, and rolling processes, and their room temperature yield strength (yield strength), high temperature yield strength (yield strength), etc. were investigated. Tables 5, 6, and 7 show a compositional comparison between the steel materials of the present invention and comparative steel materials, and Tables 8 to 12 show mechanical properties according to heating, rolling, and cooling conditions. As is clear from Tables 8 to 12, the examples of the present invention are
While all of the comparative examples have good yield strength at room temperature and high temperature, all of the comparative examples have too high yield strength at room temperature or insufficient high temperature yield strength, and the ratio of yield strength at 600℃ to room temperature yield strength is low, making them fire-resistant building materials. It is inappropriate as a
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
本発明にかかる鋼および鋼材は、高温特性が優
れ、無被覆もしくは従来の耐火被覆の20〜50％の
被覆厚さで耐火目的を達成できるので、耐火施工
にかかるコストを大幅に引き下げることが可能で
ある。また、大量生産が可能で、しかも価格も安
く、溶接などについても施工が容易で、建設工期
を短縮でき、全体として建築費が低廉で済む。
また、製造方法についても、特に難しい操業の
必要が無いので、経済的に有利である。
The steel and steel materials according to the present invention have excellent high-temperature properties and can achieve fireproofing purposes with no coating or with a coating thickness of 20 to 50% of conventional fireproof coatings, making it possible to significantly reduce the cost of fireproof construction. It is. In addition, mass production is possible, the price is low, welding is easy, the construction period can be shortened, and overall construction costs are low. Furthermore, the manufacturing method is economically advantageous as it does not require particularly difficult operations.
第１図は本発明鋼と比較鋼にかかる耐力の比較
グラフ、第２図は弾性係数の比較グラフ、第３図
は本発明鋼にかかるクリープ特性グラフ、第４図
は、比較鋼にかかるクリープ特性グラフ、第５図
は本発明にかかるＨ形鋼に吹き付けロツクウール
（湿式）を展着した柱の概略立面図ａおよびＡ−
Ａ断面図ｂ、第６図は前記柱の昇温曲線を示すグ
ラフ、第７図は前記柱の変形を示すグラフ、第８
図は本発明にかかるＨ形鋼に吹き付けロツクウー
ル（湿式）を展着したはりの概略立面図ａおよび
Ａ−Ａ断面図ｂ、第９図は前記はりの昇温曲線を
示すグラフ、第１０図は前記はりの変形を示すグ
ラフ、第１１図は防熱盾板を装着した鋼材の概略
横断面図、第１２図は、前記鋼材の昇温曲線を示
すグラフ、第１３図および第１４図はコンクリー
ト充填鋼管およびデツキプレートの昇温曲線を示
すグラフ、第１５図および第１６図は、それぞれ
放射率の異なつた無被覆鉄骨の昇温曲線を示すグ
ラフである。
１…Ｈ形鋼、２…耐火材、３…Ｈ形鋼、４…耐
火材、５…はり上側フランジ、６…はり下側フラ
ンジ、７…ウエブ、８…Ｈ形鋼、９…薄鋼板、１
０…梁、１１…取付金具、１２…コンクリート
床。
Figure 1 is a comparison graph of the yield strength of the inventive steel and comparison steel, Figure 2 is a comparison graph of elastic modulus, Figure 3 is a creep characteristic graph of the invention steel, and Figure 4 is the creep characteristic of the comparison steel. The characteristic graph, FIG. 5, is a schematic elevational view a and A- of a column in which sprayed rock wool (wet type) is spread on H-beam steel according to the present invention.
A sectional view b, FIG. 6 is a graph showing the temperature rise curve of the column, FIG. 7 is a graph showing the deformation of the column, and FIG.
The figures are a schematic elevational view a and an A-A sectional view b of a beam in which sprayed rock wool (wet type) is spread on H-section steel according to the present invention, FIG. 9 is a graph showing the temperature rise curve of the beam, and FIG. The figure is a graph showing the deformation of the beam, FIG. 11 is a schematic cross-sectional view of the steel material equipped with a heat shield plate, FIG. 12 is a graph showing the temperature rise curve of the steel material, and FIGS. 13 and 14 are Graphs showing temperature rise curves for concrete-filled steel pipes and deck plates, and FIGS. 15 and 16 are graphs showing temperature rise curves for uncoated steel frames with different emissivities, respectively. 1... H-beam steel, 2... Fireproof material, 3... H-beam steel, 4... Fireproof material, 5... Beam upper flange, 6... Beam lower flange, 7... Web, 8... H-beam steel, 9... Thin steel plate, 1
0...Beam, 11...Mounting bracket, 12...Concrete floor.
Claims (1)
1100〜1300℃の温度域で加熱後、熱間圧延を800
〜1000℃の温度範囲で終了する耐火性の優れた建
築用低降伏比鋼材の製造方法。 ２ 重量比で、 Ｃ 0.04〜0.15％、 Si 0.6％以下、 Mn 0.5〜1.6％、 Nb 0.005〜0.04％、 Mo 0.4〜0.7％、 Al 0.1％以下、 Ｎ 0.001〜0.006％、 に加えて Ti 0.005〜0.10％、 Zr 0.005〜0.03％、 Ｖ 0.005〜0.10％、 Ni 0.05〜0.5％、 Cu 0.05〜1.0％、 Cr 0.05〜1.0％、 Ｂ 0.0003〜0.002％、 Ca 0.0005〜0.005％、 REM 0.001〜0.02％ のうち１種または２種以上 残部がFeおよび不可避不純物からなる鋼片を
1100〜1300℃の温度域で加熱後、熱間圧延を800
〜1000℃の温度範囲で終了する耐火性の優れた建
築用低降伏比鋼材の製造方法。 ３ 請求１または２記載の方法により得られた鋼
材をさらに熱間工程において塑性加工する耐火性
の優れた建築用低降伏比鋼材の製造方法。 ４ 請求項１、２または３記載の方法により得ら
れた鋼材を冷間工程において塑性加工する耐火性
の優れた建築用低降伏比鋼材の製造方法。 ５ 請求項１、２、３又は４記載の方法により得
られた鋼材受熱表面に、無機系繊維質耐火薄層材
を展着せしめてなる耐火性の優れた建築用低降伏
比鋼材料。 ６ 請求項１、２、３又は４記載の方法により得
られた鋼材受熱表面に、高耐熱性塗料を被着せし
めてなる耐火性の優れた建築用低降伏比鋼材料。 ７ 請求項１、２、３又は４記載の方法により得
られた鋼材受熱表面に、防熱盾板を装着せしめて
なる耐火性の優れた建築用低降伏比鋼材料。 ８ 請求項１、２、３又は４記載の方法により得
られた中空鋼材にコンクリートを充填してなる耐
火性の優れた建築用低降伏比鋼材料。 ９ 請求項１、２、３又は４記載の方法により得
られた鋼材表面に、極薄金属を展着してなる耐火
性の優れた建築用低降伏比鋼材料。[Claims] 1. C 0.04-0.15%, Si 0.6% or less, Mn 0.5-1.6%, Nb 0.005-0.04%, Mo 0.4-0.7%, Al 0.1% or less, N 0.001-0.006% balance is a steel billet consisting of Fe and unavoidable impurities.
After heating in the temperature range of 1100 to 1300℃, hot rolling to 800℃
A method for manufacturing low yield ratio steel for construction with excellent fire resistance that terminates in the temperature range of ~1000℃. 2 In weight ratio, C 0.04-0.15%, Si 0.6% or less, Mn 0.5-1.6%, Nb 0.005-0.04%, Mo 0.4-0.7%, Al 0.1% or less, N 0.001-0.006%, in addition to Ti 0.005 ~0.10%, Zr 0.005~0.03%, V 0.005~0.10%, Ni 0.05~0.5%, Cu 0.05~1.0%, Cr 0.05~1.0%, B 0.0003~0.002%, Ca 0.0005~0.005%, REM 0.001~0.02 % of one or more of the following: A steel billet with the balance consisting of Fe and unavoidable impurities.
After heating in the temperature range of 1100 to 1300℃, hot rolling to 800℃
A method for manufacturing low yield ratio steel for construction with excellent fire resistance that terminates in the temperature range of ~1000℃. 3. A method for producing a low yield ratio steel material for construction with excellent fire resistance, which further comprises plastic working the steel material obtained by the method according to claim 1 or 2 in a hot process. 4. A method for producing a low yield ratio steel material for construction with excellent fire resistance, which comprises plastically working the steel material obtained by the method according to claim 1, 2 or 3 in a cold process. 5. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by spreading an inorganic fibrous fire-resistant thin layer material on the heat-receiving surface of the steel material obtained by the method according to claim 1, 2, 3 or 4. 6. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by coating a heat-receiving surface of a steel material obtained by the method according to claim 1, 2, 3, or 4 with a highly heat-resistant paint. 7. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by attaching a heat shield plate to the heat-receiving surface of the steel material obtained by the method according to claim 1, 2, 3 or 4. 8. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by filling a hollow steel material obtained by the method according to claim 1, 2, 3 or 4 with concrete. 9. A low yield ratio steel material for construction with excellent fire resistance, which is obtained by spreading an extremely thin metal onto the surface of a steel material obtained by the method according to claim 1, 2, 3 or 4.
Priority Applications (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 602362 CA1320110C (en) | 1988-06-13 | 1989-06-09 | Process for manufacturing building construction steel having excellent fire resistance and low yield ratio, and construction steel material |
| US07/364,608 US4990196A (en) | 1988-06-13 | 1989-06-09 | Process for manufacturing building construction steel having excellent fire resistance and low yield ratio |
| EP19890305942 EP0347156B2 (en) | 1988-06-13 | 1989-06-13 | Process for manufacturing building construction steel having excellent fire resistance and low yield ratio, and construction steel obtained thereby |
| DE1989628336 DE68928336T3 (en) | 1988-06-13 | 1989-06-13 | Process for the production of structural steels with high fire resistance and low yield strength ratio and structural steel produced thereby |
| US07/614,076 US5147474A (en) | 1988-06-13 | 1990-11-13 | Building construction steel having excellent fire resistance and low yield ratio |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63-143740 | 1988-06-13 | ||
| JP14374088 | 1988-06-13 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0277523A JPH0277523A (en) | 1990-03-16 |
| JPH0450362B2 true JPH0450362B2 (en) | 1992-08-14 |
Family
ID=15345914
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP13932889A Granted JPH0277523A (en) | 1988-06-13 | 1989-06-02 | Production of building low yield ratio steel having excellent fire resistance and building steel material using same steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0277523A (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH036322A (en) * | 1989-06-02 | 1991-01-11 | Nippon Steel Corp | Production of low yield ratio steel products for building having excellent fire resistivity and steel material for building formed by using these steel products |
| JPH072968B2 (en) * | 1989-09-22 | 1995-01-18 | 新日本製鐵株式会社 | Method for manufacturing structural steel with excellent fire resistance |
| JPH0713251B2 (en) * | 1990-03-22 | 1995-02-15 | 新日本製鐵株式会社 | Manufacturing method of thin low yield ratio steel for construction with excellent fire resistance and weldability |
| JPH0448047A (en) * | 1990-06-18 | 1992-02-18 | Nippon Steel Corp | Fire proof coat on refractory steel for structural use |
| JPH0713249B2 (en) * | 1990-06-26 | 1995-02-15 | 新日本製鐵株式会社 | Manufacturing method of low yield ratio steel with excellent fire resistance |
| JPH0456721A (en) * | 1990-06-26 | 1992-02-24 | Nippon Steel Corp | Production of steel with low yield ratio for construction use excellent in refractoriness |
| JPH0713250B2 (en) * | 1990-06-26 | 1995-02-15 | 新日本製鐵株式会社 | Manufacturing method of low yield ratio steel with excellent fire resistance |
| JPH0765097B2 (en) * | 1990-07-27 | 1995-07-12 | 新日本製鐵株式会社 | Method for producing H-section steel excellent in fire resistance and weld toughness |
| JPH0737647B2 (en) * | 1990-08-27 | 1995-04-26 | 新日本製鐵株式会社 | Method for producing low yield ratio H-section steel excellent in fire resistance and toughness |
| JP2596853B2 (en) * | 1990-10-20 | 1997-04-02 | 新日本製鐵株式会社 | Method for producing intragranular ferrite shaped steel with excellent base metal toughness as welded and excellent weld toughness |
| JP2730800B2 (en) * | 1990-12-27 | 1998-03-25 | 新日本製鐵株式会社 | Manufacturing method of ERW steel pipe with excellent fire resistance |
| JP2579842B2 (en) * | 1991-03-08 | 1997-02-12 | 新日本製鐵株式会社 | Method for producing intragranular ferritic section steel with excellent toughness as rolled and excellent weld toughness |
| JP2579841B2 (en) * | 1991-03-08 | 1997-02-12 | 新日本製鐵株式会社 | Method for producing as-rolled intragranular ferritic steel with excellent fire resistance and toughness |
| JP2828356B2 (en) * | 1991-07-19 | 1998-11-25 | 新日本製鐵株式会社 | Method for producing boron-treated thin steel for structural use with excellent fire resistance |
| JPH05112822A (en) * | 1991-10-18 | 1993-05-07 | Kobe Steel Ltd | Manufacture of 400n/mm2 class fire resistant steel for building construction having low yield ratio |
| JPH05271753A (en) * | 1992-03-23 | 1993-10-19 | Nippon Steel Corp | Manufacture of h-beam excellent in high temperature strength |
| JP2785588B2 (en) * | 1992-05-11 | 1998-08-13 | 日本鋼管株式会社 | Structural refractory steel excellent in weather resistance and excellent in high-temperature strength characteristics after reheating and method for producing the same |
| JP2661845B2 (en) * | 1992-09-24 | 1997-10-08 | 新日本製鐵株式会社 | Manufacturing method of oxide-containing refractory section steel by controlled rolling |
| JP2760713B2 (en) * | 1992-09-24 | 1998-06-04 | 新日本製鐵株式会社 | Method for producing controlled rolled steel with excellent fire resistance and toughness |
| JPH06316724A (en) * | 1993-03-04 | 1994-11-15 | Kobe Steel Ltd | Production of refractory steel plate for construction use, low in acoustic anisotropy |
| MX9707729A (en) * | 1996-02-13 | 1998-02-28 | Nippon Steel Corp | Welded joint of high fatigue strength. |
| JP4954507B2 (en) * | 2004-07-28 | 2012-06-20 | 新日本製鐵株式会社 | H-section steel excellent in fire resistance and method for producing the same |
| JP4571915B2 (en) * | 2006-02-08 | 2010-10-27 | 新日本製鐵株式会社 | Refractory thick steel plate and manufacturing method thereof |
| CN104178697B (en) * | 2014-08-26 | 2016-05-11 | 武汉钢铁(集团)公司 | A kind of high-temperature resistant anti-shock reinforcing bar and production method thereof |
| CN106854732B (en) * | 2016-12-13 | 2018-06-22 | 武汉钢铁有限公司 | The high tenacity low-yield-ratio fire resistant weathering steel and its production method of tensile strength >=600MPa |
| JP7077802B2 (en) * | 2018-06-12 | 2022-05-31 | 日本製鉄株式会社 | Low yield ratio refractory steel sheet |
-
1989
- 1989-06-02 JP JP13932889A patent/JPH0277523A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0277523A (en) | 1990-03-16 |
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