JPH07207336A - Production of refractory steel products for building structural purpose - Google Patents
Production of refractory steel products for building structural purposeInfo
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- JPH07207336A JPH07207336A JP12390194A JP12390194A JPH07207336A JP H07207336 A JPH07207336 A JP H07207336A JP 12390194 A JP12390194 A JP 12390194A JP 12390194 A JP12390194 A JP 12390194A JP H07207336 A JPH07207336 A JP H07207336A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、耐火鋼材の製造方法に
関し、さらに詳しくは、厚肉材においても常温での降伏
比が低く、十分な高温耐力と優れた溶接性を有する490N
/mm2級の建築構造用耐火鋼材の製造方法に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a refractory steel material, more specifically, a thick-walled material having a low yield ratio at room temperature, a sufficient high-temperature resistance and excellent weldability.
The present invention relates to a manufacturing method of a fireproof steel material for building structure of / mm 2 class.
【０００２】[0002]
【従来の技術】建築構造物では、火災時に鉄骨が高温に
さらされると鉄骨強度が低下し、建築物として必要な耐
力が維持できなくなるため、耐火被覆で鉄骨を保護する
ことが建築基準法で定められている。2. Description of the Related Art In a building structure, if the steel frame is exposed to high temperatures during a fire, the strength of the steel frame will decrease and it will not be possible to maintain the proof stress required for the building. It is set.
【０００３】従来のSi−Mn系の建築構造用鋼材では、火
災時に鋼材温度が 350℃以上になるとその耐力が常温規
格の2/3 以下に低下し、構造上必要な耐力（長期許容応
力度）を下回るため、耐火被覆によって鋼材温度の上昇
を抑制しているが、工事費の増加や工期の長期化という
問題がある。In the conventional Si-Mn-based steel for building structures, when the steel temperature rises to 350 ° C or more during a fire, the proof stress decreases to 2/3 or less of the room temperature standard, and the proof stress required for the structure (long-term allowable stress However, the refractory coating suppresses the rise in steel temperature, but there are problems such as an increase in construction costs and a longer construction period.
【０００４】しかし、1987年に施行された『新耐火設計
法』により、高温での耐力が優れた鋼材（耐火鋼材）を
使用すれば、耐火被覆の削減または省略が可能になっ
た。この耐火鋼材は立体駐車場、外部鉄骨建築物、アト
リウムなどを中心に採用されているが、特に、建築物の
高層化、大スパン化に伴い厚肉の耐火鋼材の必要性が高
まっている。However, the "new fireproof design method" enforced in 1987 made it possible to reduce or omit the fireproof coating by using a steel material (fireproof steel material) having an excellent yield strength at high temperature. This fire-resistant steel material is mainly used in multi-storey parking lots, external steel-framed buildings, atriums, etc., but in particular, the need for thick-walled fire-resistant steel material is increasing as the building becomes taller and has a larger span.
【０００５】現状、高温での耐力が優れた鋼材として、
ボイラ・圧力容器用Cr−Mo鋼がある。しかし、この鋼材
は 600℃での耐力は常温規格値の2/3 以上を有するが、
C 量が高いために溶接性および大入熱溶接継手靱性が悪
く、溶接施工上難点がある。このために、 600℃におい
ても高い耐力を有し、かつ溶接性に優れた従来鋼と同等
の設計・施工ができる耐火鋼材がいくつか提案されてい
る。At present, as a steel material excellent in proof stress at high temperature,
Cr-Mo steel for boilers and pressure vessels is available. However, although this steel has a yield strength at 600 ° C of 2/3 or more of the normal temperature standard value,
Since the C content is high, the weldability and high heat input welded joint toughness are poor, and there are difficulties in welding work. For this reason, there have been proposed some refractory steel materials that have a high yield strength even at 600 ° C and can be designed and constructed in the same manner as conventional steels, which have excellent weldability.
【０００６】例えば、特開平3-173715号公報に開示され
ている鋼は、Cr、MoおよびNbを複合添加し、制御圧延法
により製造され、優れた高温耐力を有しているが、板厚
が25mmと薄く、厚肉材を対象としていない。また、特開
平3-6322号公報に開示されている鋼は、多量のMoを添加
した鋼をＡr3変態点以下から加速冷却することによりミ
クロ組織をフェライトとベイナイトの混合組織とし、常
温での降伏比を低く抑えて、 600℃における耐力を確保
している。しかし、加速冷却のままでは鋼材の残留応力
が高いため、ガス切断による条切り時にキャンバーや反
りの形状不良が発生しやすいという欠点がある。[0006] For example, the steel disclosed in Japanese Patent Laid-Open No. 3-173715 is manufactured by a controlled rolling method in which Cr, Mo and Nb are added in combination, and has excellent high temperature proof stress. Is as thin as 25mm and is not intended for thick materials. Further, the steel disclosed in Japanese Patent Application Laid-Open No. 3-6322 has a microstructure to be a mixed structure of ferrite and bainite by accelerating cooling of a steel containing a large amount of Mo from the Ar 3 transformation point or lower, and The yield ratio is kept low and the yield strength at 600 ° C is secured. However, the residual stress of the steel material is high in the case of accelerated cooling as it is, and thus there is a drawback that defective shapes such as camber and warp are likely to occur at the time of cutting by gas cutting.
【０００７】[0007]
【発明が解決しようとする課題】優れた条切り特性を有
するには、板厚によらず制御圧延ままが有効であるが、
厚肉材の場合、強度を確保するために Ceq（炭素当量)
や PCM（溶接割れ感受性組成）を高くせざるを得なく、
溶接性が劣化する。一方、 Ceqを高めることなく強度の
上昇を図る手段として加速冷却法があるが、加速冷却ま
までは鋼材の残留応力が高いため、ガス切断での条切り
特性が悪い。また、加速冷却法での条切り特性の改善に
は加速冷却＋焼戻し法が有効であるが、この方法ではミ
クロ組織がベイナイトとなり、しかも焼戻し時に高温強
度を向上させるために添加したMo、Nbが析出するために
常温での降伏比が高くなる。In order to have excellent stripping properties, controlled rolling is effective regardless of the plate thickness.
For thick materials, Ceq (carbon equivalent) to ensure strength
And P CM (welding crack susceptibility composition) must be increased,
Weldability deteriorates. On the other hand, there is an accelerated cooling method as a means of increasing the strength without increasing Ceq, but with accelerated cooling as it is, the residual stress of the steel material is high, resulting in poor stripping characteristics in gas cutting. In addition, although the accelerated cooling + tempering method is effective for improving the stripping property in the accelerated cooling method, this method makes the microstructure bainite, and Mo and Nb added to improve the high temperature strength during tempering are used. The yield ratio increases at room temperature because of precipitation.
【０００８】本発明は、上記の問題点を解決するために
なされたもので、化学成分を調整し、加熱温度と圧延終
了温度を限定する制御圧延を行い、圧延終了後Ａc1〜Ａ
c3変態点の温度範囲に再加熱し焼入れした後、焼戻しす
ることにより、厚肉材においても、高温で高い耐力を有
し、かつ常温での降伏比が低く、優れた溶接性および条
切り特性を有する490N/mm2級建築構造用耐火鋼材の製造
方法を提供することを目的とする。[0008] The present invention has been made to solve the above problems, by adjusting the chemical components, and controls rolling to limit the heating temperature and the rolling end temperature, the finish rolling after the Ac 1 to A
After reheating quenching to a temperature range of c 3 transformation point, by tempering, even in thick material, it has a high yield strength at high temperatures and low yield ratio at room temperature, excellent weldability and conditions cut An object of the present invention is to provide a method for producing a 490 N / mm 2 class fire resistant steel material for building structures having characteristics.
【０００９】[0009]
【課題を解決するための手段】本発明は、従来の建築用
鋼材における上記の問題点に鑑み、本発明者らが鋭意研
究を行った結果、 Ceqを高めることなく、強度上昇を図
り、かつ常温での低降伏比を確保する手段として、制御
圧延後にＡc1〜Ａc3変態点の温度範囲で再加熱し焼入れ
した後、焼戻しを行うことによりミクロ組織をフェライ
トとベイナイトの混合組織とすることが有効であるとい
う知見を得て完成したものである。SUMMARY OF THE INVENTION In view of the above problems in conventional steel materials for construction, the present invention has conducted intensive research by the present inventors, and as a result, increased strength without increasing Ceq, and As a means for ensuring a low yield ratio at room temperature, after re-heating in the temperature range of the Ac 1 to Ac 3 transformation point after controlled rolling and quenching, tempering is performed to make the microstructure a mixed structure of ferrite and bainite. Was completed with the knowledge that is effective.
【００１０】すなわち、(1) C:0.04〜0.14％、 Si:0.05
〜0.50％、 Mn:0.50〜1.50％、P:0.020 ％以下、S:0.00
5 ％以下、 Mo:0.10〜0.40％、 V:0.005〜0.060 ％、N
b:0.005〜0.060 ％、Ti:0.005〜0.030 ％、Al:0.002〜
0.10％を含有し、残部がFeおよび不可避的不純物からな
り、かつ、 PCMの値が0.21％以下である鋼片を1050℃以
上の温度に加熱し、 850〜950 ℃の温度範囲で圧延終了
後、Ａc1〜Ａc3変態点の温度範囲に再加熱し焼入れした
後、さらに 500〜650 ℃の温度で焼戻しする建築構造用
耐火鋼材の製造方法である。ただし、 PCM=C+Si/30+Mn/
20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B（％）That is, (1) C: 0.04 to 0.14%, Si: 0.05
~ 0.50%, Mn: 0.50 to 1.50%, P: 0.020% or less, S: 0.00
5% or less, Mo: 0.10 to 0.40%, V: 0.005 to 0.060%, N
b: 0.005-0.060%, Ti: 0.005-0.030%, Al: 0.002-
A steel slab containing 0.10% and the balance Fe and unavoidable impurities and having a P CM value of 0.21% or less is heated to a temperature of 1050 ° C or higher, and rolling is completed in the temperature range of 850 to 950 ° C. After that, it is a method for producing a refractory steel material for a building structure, which comprises reheating to a temperature range of Ac 1 to Ac 3 transformation point, quenching, and further tempering at a temperature of 500 to 650 ° C. However, P CM = C + Si / 30 + Mn /
20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (%)
【００１１】(2) 上記(1) に、さらに Cu:0.05〜0.40
％、 Ni:0.05〜0.40％、 Cr:0.10〜0.40％、 Ca:0.0005
〜0.0050％の内から選んだ１種または２種以上を含有す
る建築構造用耐火鋼材の製造方法である。(2) In addition to the above (1), Cu: 0.05 to 0.40
%, Ni: 0.05 to 0.40%, Cr: 0.10 to 0.40%, Ca: 0.0005
It is a manufacturing method of the refractory steel material for building structures containing 1 type (s) or 2 or more types selected from 0.0050%.
【００１２】[0012]
【作用】まず、本発明における化学成分の限定理由につ
いて説明する。C は、強度上昇に寄与する元素である
が、0.04％未満では強度を確保することは困難であり、
一方、0.14％を超えて添加すると、溶接性および靱性を
劣化させる。したがって、C 添加量は0.04〜0.14％の範
囲とする。First, the reasons for limiting the chemical components in the present invention will be described. C is an element that contributes to the strength increase, but if it is less than 0.04%, it is difficult to secure the strength,
On the other hand, if added over 0.14%, the weldability and toughness deteriorate. Therefore, the amount of C added is in the range of 0.04 to 0.14%.
【００１３】Siは、脱酸のために必須の元素であるが、
0.05％未満ではその効果が少なく、一方、0.50％を超え
て添加すると溶接性を劣化させる。したがって、Si添加
量は0.05〜0.50％の範囲とする。Si is an essential element for deoxidation,
If it is less than 0.05%, its effect is small, while if it exceeds 0.50%, the weldability is deteriorated. Therefore, the amount of Si added is set to the range of 0.05 to 0.50%.
【００１４】Mnは、強度および靱性を確保するために必
要な元素であるが、0.50％未満ではこのような効果は少
なく、一方、1.50％を超えて添加すると溶接性を劣化さ
せる。したがって、Mn添加量は0.50〜1.50％の範囲とす
る。Mn is an element necessary for securing strength and toughness, but if it is less than 0.50%, such an effect is small, while if it exceeds 1.50%, weldability deteriorates. Therefore, the amount of Mn added is in the range of 0.50 to 1.50%.
【００１５】P は、 0.020％を超えて含有するとミクロ
偏析により溶接性および靱性を劣化させる。したがっ
て、P 含有量は 0.020％以下とする。When P exceeds 0.020%, P deteriorates weldability and toughness due to microsegregation. Therefore, the P content should be 0.020% or less.
【００１６】S は、 0.005％を超えて含有すると粗大な
Ａ系介在物を形成しやすくなり、靱性を劣化させる。し
たがって、S 含有量は 0.005％以下とする。If S is contained in an amount of more than 0.005%, coarse A type inclusions are likely to be formed and the toughness is deteriorated. Therefore, the S content should be 0.005% or less.
【００１７】Moは、高温強度を確保するために不可欠な
元素であり、 600℃における耐力を大幅に上昇させる。
しかしながら、0.10％未満ではこのような効果は得られ
ず、一方、0.40％を超えて添加すると大入熱溶接継手靱
性を劣化させる。したがって、Mo添加量は0.10〜0.40％
の範囲とする。Mo is an indispensable element for ensuring high temperature strength and significantly increases the yield strength at 600 ° C.
However, if it is less than 0.10%, such an effect cannot be obtained, while if it exceeds 0.40%, the toughness of the high heat input welded joint is deteriorated. Therefore, the amount of Mo added is 0.10 to 0.40%
The range is.
【００１８】V は、析出硬化により高温強度の上昇に有
効な元素であるが、0.005 ％未満ではこの効果は少な
く、一方、0.060 ％を超えて添加すると溶接性が劣化す
る。したがって、V 添加量は 0.005〜0.060 ％の範囲と
する。V is an element effective in increasing the high temperature strength by precipitation hardening, but if it is less than 0.005%, this effect is small, while if it exceeds 0.060%, the weldability deteriorates. Therefore, the amount of V added should be in the range of 0.005 to 0.060%.
【００１９】Nbは、析出硬化による高温強度の上昇およ
び細粒化による靱性の向上が図られる元素であるが、0.
005 ％未満ではこれらの効果は少なく、一方、0.060 ％
を超えて添加すると大入熱溶接継手靱性が劣化する。し
たがって、Nb添加量は 0.005〜0.060 ％の範囲とする。Nb is an element capable of increasing the high temperature strength by precipitation hardening and improving the toughness by fine graining.
Below 005%, these effects are small, while at 0.060%
If added over the range, the toughness of the high heat input welded joint deteriorates. Therefore, the amount of Nb added should be in the range of 0.005 to 0.060%.
【００２０】Tiは、オーステナイト粒の粗大化の抑制お
よびフェライトの生成促進により、靱性の向上に有効な
元素であるが、 0.005％未満ではこのような効果は少な
く、一方、 0.030％を超えて添加すると靱性を劣化させ
る。したがって、Ti添加量は0.005〜0.030 ％の範囲と
する。Ti is an element effective in improving the toughness by suppressing the coarsening of austenite grains and promoting the generation of ferrite, but if it is less than 0.005%, such an effect is small, while if it exceeds 0.030%, it is added. This deteriorates the toughness. Therefore, the amount of Ti added is in the range of 0.005 to 0.030%.
【００２１】Alは、脱酸に必要であるとともに結晶粒の
微細化に寄与する元素であるが、0.002 ％未満ではこれ
らの効果は少なく、一方、0.10％を超えて添加すると酸
化物系介在物が多くなり靱性を劣化させる。したがっ
て、Al添加量は 0.002〜0.10％の範囲とする。ただし、
脱酸を強化したい場合には、 0.020〜0.10％の範囲が望
ましい。Al is an element that is necessary for deoxidation and contributes to the refinement of crystal grains, but if it is less than 0.002%, these effects are small, while if it is added in excess of 0.10%, oxide-based inclusions are included. Increases, which deteriorates toughness. Therefore, the amount of Al added should be in the range of 0.002 to 0.10%. However,
When strengthening deoxidation, the range of 0.020 to 0.10% is desirable.
【００２２】なお、本発明においては、上記の元素の他
に必要に応じて、Cu、Ni、CrおよびCaの内の１種または
２種以上を添加することができる。In the present invention, in addition to the above elements, one or more of Cu, Ni, Cr and Ca can be added if necessary.
【００２３】Cuは、析出硬化による強度上昇に有効な元
素であるが、0.05％未満ではこのような効果は少なく、
一方、0.40％を超えて添加すると熱間加工性および溶接
性を損なう。したがって、Cu添加量は0.05〜0.40％の範
囲とする。Cu is an element effective in increasing the strength by precipitation hardening, but if it is less than 0.05%, such an effect is small,
On the other hand, if added in excess of 0.40%, hot workability and weldability are impaired. Therefore, the Cu addition amount is set to the range of 0.05 to 0.40%.
【００２４】Niは、強度と靱性の向上に有効な元素であ
るが、0.05％未満ではこれらの効果は少なく、一方、0.
40％を超えて添加してもこのような効果は飽和し、経済
的にも無駄である。したがって、Ni添加量は0.05〜0.40
％の範囲とする。Ni is an element effective for improving the strength and toughness, but if it is less than 0.05%, these effects are small, while on the other hand,
Even if added in excess of 40%, such effects will be saturated, which is economically wasteful. Therefore, the amount of Ni added is 0.05 to 0.40.
The range is%.
【００２５】Crは、高温強度の上昇に有効な元素である
が、0.10％未満ではこの効果は少なく、一方、0.40％を
超えて添加すると溶接性および溶接継手靱性が劣化す
る。したがって、Cr添加量は0.10〜0.40％の範囲とす
る。Cr is an element effective for increasing the high temperature strength, but if it is less than 0.10%, this effect is small, while if it exceeds 0.40%, the weldability and weld joint toughness deteriorate. Therefore, the Cr addition amount is set to the range of 0.10 to 0.40%.
【００２６】Caは、微量で板厚方向の特性を改善する元
素であるが、0.0005％未満ではこの効果は少なく、一
方、0.0050％を超えて添加すると鋼中の非金属介在物を
増大させ内部欠陥の原因となる。したがって、Ca添加量
は0.0005〜0.0050％の範囲とする。[0026] Ca is an element that improves the properties in the plate thickness direction with a trace amount, but if it is less than 0.0005%, this effect is small, while if it exceeds 0.0050%, it increases the non-metallic inclusions in the steel and increases the internal content. Cause defects. Therefore, the amount of Ca added is in the range of 0.0005 to 0.0050%.
【００２７】さらに、本発明では溶接時の低温割れ防止
のために行われる予熱を省略する目的で PCM (溶接割れ
感受性組成) を0.21％以下に限定する。ただし、 PCM=C
+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B（％）Furthermore, in the present invention to limit P CM (the weld crack susceptibility composition) below 0.21% is omitted purpose preheating performed to prevent cold cracking during welding. However, P CM = C
+ Si / 30 + Mn / 20 + Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (%)
【００２８】次に、本発明における加熱、圧延、および
熱処理条件の限定理由について説明する。加熱温度は高
温耐力の確保に必要なNbを固溶させるために下限を1050
℃とする。また、圧延終了温度については、圧延終了温
度が 850℃未満では、フェライト粒の微細化により耐震
性の面から建築構造用鋼材に要求される80％以下の降伏
比を確保することができず、さらに、集合組織に起因し
て音響異方性が高くなり、超音波斜角探傷において屈折
角や探傷感度が変化するために溶接欠陥部の検出作業が
困難となる。一方、圧延終了温度が 950℃を超えると、
オーステナイト粒が粗粒になるため母材靱性が劣化す
る。したがって、圧延終了温度は 850〜950 ℃の温度範
囲に限定する。Next, the reasons for limiting the heating, rolling and heat treatment conditions in the present invention will be described. The heating temperature has a lower limit of 1050 in order to form a solid solution with Nb, which is necessary to secure high temperature proof stress.
℃. Regarding the rolling end temperature, if the rolling end temperature is less than 850 ° C, the yield ratio of 80% or less required for building structural steel cannot be secured from the viewpoint of earthquake resistance due to the refinement of ferrite grains, Further, the acoustic anisotropy is increased due to the texture, and the refraction angle and the flaw detection sensitivity are changed in the ultrasonic oblique flaw detection, which makes it difficult to detect the welding defect portion. On the other hand, if the rolling end temperature exceeds 950 ° C,
Since the austenite grains become coarse grains, the toughness of the base material deteriorates. Therefore, the rolling finish temperature is limited to the temperature range of 850 to 950 ° C.
【００２９】上述の条件で熱間圧延（制御圧延）を終了
した後、Ａc1〜Ａc3変態点の二相域温度で再加熱し焼入
れを行う。この理由は、前述したように、Ceq を高める
ことなく強度上昇を図るためであるが、降伏比の上昇を
抑制するために、ベイナイト組織中に軟質のフェライト
を生成させ、これによって80％以下の降伏比を確保する
ことができる。After the hot rolling (controlled rolling) is completed under the above conditions, the material is reheated at the temperature of the two-phase region of the Ac 1 to Ac 3 transformation points to quench it. The reason for this is, as described above, to increase the strength without increasing Ceq, but in order to suppress the increase in the yield ratio, soft ferrite is generated in the bainite structure, which results in 80% or less. The yield ratio can be secured.
【００３０】さらに残留応力を除去して条切り特性を向
上させるために 500〜650 ℃の温度範囲で焼戻しを行
う。焼戻し温度は 500℃未満では残留応力の除去が不十
分であり、一方、 650℃を超えると常温強度が大幅に低
下する。したがって、焼戻し温度は 500〜650 ℃の範囲
に限定する。Further, tempering is performed in a temperature range of 500 to 650 ° C. in order to remove the residual stress and improve the stripping property. If the tempering temperature is less than 500 ° C, residual stress is not sufficiently removed, while if it exceeds 650 ° C, the room temperature strength is significantly reduced. Therefore, the tempering temperature is limited to the range of 500-650 ° C.
【００３１】以上述べた製造条件により、高温で高い耐
力を確保し、さらに常温の降伏比が低く、かつ、優れた
溶接性および条切り特性を有する490N/mm2級建築構造用
耐火鋼材を得ることができる。According to the above-mentioned manufacturing conditions, a high yield strength at a high temperature is secured, a yield ratio at room temperature is low, and a 490 N / mm 2 class fireproof steel for building structure having excellent weldability and slitting properties is obtained. be able to.
【００３２】[0032]
【実施例】以下に、実施例を挙げて本発明について説明
するが、本発明はこれらの実施例により限定されるもの
ではない。例えば、本発明は薄肉材にも適用が可能であ
る。The present invention will be described below with reference to examples, but the present invention is not limited to these examples. For example, the present invention can be applied to a thin material.
【００３３】供試鋼板は表１に示す化学成分を有する鋼
片を表２に示す加熱・圧延・熱処理条件にしたがって、
板厚70mmに仕上げたものである。これらの鋼板から試験
片を採取し、常温引張試験、シャルピ衝撃試験、 600℃
における高温引張試験および最高かたさ試験を行った。
その結果を表２に示す。なお、最高かたさ試験はJISZ 3
101に準じて行った。The test steel sheet was prepared by subjecting steel pieces having the chemical composition shown in Table 1 to the heating, rolling and heat treatment conditions shown in Table 2.
It is finished to a plate thickness of 70 mm. Test pieces were taken from these steel sheets and subjected to normal temperature tensile test, Charpy impact test, 600 ℃
The high temperature tensile test and the maximum hardness test were conducted.
The results are shown in Table 2. The highest hardness test is JIS Z 3
It carried out according to 101.
【００３４】表１に本発明法Ａ〜Ｇおよび比較例Ｈ〜Ｍ
の化学成分を、表２に加熱・圧延・加速冷却・熱処理条
件を、表３に引張特性、衝撃特性、高温特性および溶接
性をそれぞれ示す。Table 1 shows the methods A to G of the present invention and comparative examples H to M.
Table 2 shows the heating, rolling, accelerated cooling, and heat treatment conditions in Table 2, and Table 3 shows the tensile properties, impact properties, high temperature properties, and weldability.
【００３５】[0035]
【表１】 [Table 1]
【００３６】[0036]
【表２】 [Table 2]
【００３７】[0037]
【表３】 [Table 3]
【００３８】表３から明らかなように、本発明法Ａ〜Ｇ
はいずれも 600℃における耐力が常温規格の2/3(197N/m
m2) 以上の優れた高温耐力を有し、常温での引張特性は
490N/mm2級の規格値（降伏点または 0.2％耐力:295N/mm
2 以上、引張強さ:490〜610N/mm2）および耐震性の面か
ら建築構造用鋼材に要求される80％以下の降伏比を十分
に満足している。また、シャルピー衝撃試験における母
材の破面遷移温度も-40 ℃以下と良好である。さらに、
最高硬さもHV300 以下を満足し、良好な溶接性を有して
いる。As is clear from Table 3, the present invention methods A to G
In both cases, the proof stress at 600 ° C is 2/3 of the normal temperature standard (197 N / m
It has an excellent high temperature proof stress of more than m 2 ) and has a tensile property at room temperature.
490N / mm Class 2 standard value (yield point or 0.2% proof stress: 295N / mm
2 or more, tensile strength: 490 to 610 N / mm 2 ) and seismic resistance, the yield ratio of 80% or less required for steel for building structures is sufficiently satisfied. Also, the fracture surface transition temperature of the base material in the Charpy impact test is good at -40 ° C or lower. further,
It has a maximum hardness of HV300 or less and has good weldability.
【００３９】一方、比較例ＨはC および PCMが本発明の
範囲から高めに外れているため、母材靱性および溶接性
が悪い。比較例ＩはMoが本発明の範囲から高めに外れて
いるため、母材靱性および溶接性が悪い。比較例ＪはTi
が添加されていないため母材靱性が悪い。また、比較例
Ｋ、Ｌでは、前者はMoが、後者はNbがそれぞれ添加され
ていないため、 600℃における耐力が低い。さらに比較
例ＭもV が添加されていないため、 600℃における耐力
が低い。On the other hand, in Comparative Example H, since C and P CM are out of the scope of the present invention, the toughness and weldability of the base metal are poor. In Comparative Example I, since Mo is out of the range of the present invention, the base material toughness and weldability are poor. Comparative Example J is Ti
Is not added, the base material toughness is poor. Further, in Comparative Examples K and L, since the former is not added with Mo and the latter is not added with Nb, the yield strength at 600 ° C. is low. Further, Comparative Example M also has low yield strength at 600 ° C. because V is not added.
【００４０】また、比較例A1〜A4は本発明法Ａと同じ化
学成分の鋼片を本発明の製造条件範囲外の条件で鋼板に
仕上げたものである。比較例A1は圧延ままであり、Ａc1
〜Ａc3変態点温度での再加熱焼入れ処理を行っていない
ため、 600℃における耐力が低い。比較例A2は加熱温度
が1000℃と本発明の限定範囲から低めに外れているた
め、Nbが十分に固溶せず常温強度および 600℃における
耐力が低い。比較例A3は圧延終了温度が 825℃と本発明
の限定範囲から低めに外れているため、フェライトが細
粒となり常温での降伏比が80％を超えている。比較例A4
は圧延終了温度が965℃と本発明の限定範囲から高めに
外れているため、オーステナイトが粗粒となり母材の破
面遷移温度が高い。Further, in Comparative Examples A1 to A4, steel plates having the same chemical composition as the method A of the present invention were finished into steel plates under the conditions outside the manufacturing condition range of the present invention. Comparative Example A1 was as rolled and Ac 1
~ Ac 3 Since the reheating and quenching treatment at the transformation temperature is not performed, the yield strength at 600 ° C is low. In Comparative Example A2, the heating temperature is 1000 ° C., which is outside the limited range of the present invention, so Nb is not sufficiently solid-dissolved, and the room temperature strength and the yield strength at 600 ° C. are low. In Comparative Example A3, the rolling end temperature is 825 ° C, which is outside the range of the present invention, so the ferrite becomes fine grains and the yield ratio at room temperature exceeds 80%. Comparative Example A4
Since the rolling end temperature is 965 ° C., which is outside the limited range of the present invention, austenite becomes coarse grains and the fracture surface transition temperature of the base material is high.
【００４１】なお、上記実施例は厚鋼板の製造方法に関
するものであるが、本発明は他の鋼製品、例えば条鋼、
形鋼の製造にも適応し得ることは言うまでもない。Although the above embodiment relates to a method for manufacturing a thick steel plate, the present invention is applicable to other steel products, such as bar steel,
It goes without saying that it can also be applied to the production of shaped steel.
【００４２】[0042]
【発明の効果】以上述べたところから明らかなように、
高層や大スパンの鉄骨建築物に使用される厚肉鋼材にお
いても、本発明によれば、 600℃においても高い耐力を
確保し、かつ、常温の降伏比が低く、さらに優れた溶接
性および条切り特性を有する490N/mm2級建築構造用耐火
鋼材を得ることができる。このため、従来必要とされて
いた耐火被覆を大幅に低減あるいは省略することがで
き、さらに、耐震性の面から構造物の安全性を高め、か
つ、溶接施工能率を向上させることができる。As is apparent from the above description,
According to the present invention, even in thick-walled steel materials used for high-rise or large-span steel structures, high yield strength can be secured even at 600 ° C, and the yield ratio at room temperature is low, and further excellent weldability and It is possible to obtain a 490 N / mm 2 class fire resistant steel material for building structures having cutting characteristics. Therefore, the conventionally required fireproof coating can be greatly reduced or omitted, and further, the safety of the structure can be improved from the viewpoint of earthquake resistance, and the welding work efficiency can be improved.
Claims (2)
n:0.50〜1.50％、P:0.020 ％以下、S:0.005 ％以下、 M
o:0.10〜0.40％、 V:0.005〜0.060 ％、Nb:0.005〜0.06
0 ％、Ti:0.005〜0.030 ％、Al:0.002〜0.10％を含有
し、残部がFeおよび不可避的不純物からなり、かつ、 P
CMの値が0.21％以下である鋼片を1050℃以上の温度に加
熱し、 850〜950 ℃の温度範囲で圧延終了後、Ａc1〜Ａ
c3変態点の温度範囲に再加熱し焼入れした後、さらに 5
00〜650 ℃の温度で焼戻しすることを特徴とする建築構
造用耐火鋼材の製造方法。ただし、 PCM=C+Si/30+Mn/20
+Cu/20+Ni/60+Cr/20+Mo/15+V/10+5B（％）1. C: 0.04 to 0.14%, Si: 0.05 to 0.50%, M
n: 0.50 to 1.50%, P: 0.020% or less, S: 0.005% or less, M
o: 0.10 to 0.40%, V: 0.005 to 0.060%, Nb: 0.005 to 0.06
0%, Ti: 0.005-0.030%, Al: 0.002-0.10%, the balance Fe and unavoidable impurities, and P
After the steel slab with a CM value of 0.21% or less is heated to a temperature of 1050 ° C or higher and rolling is completed in the temperature range of 850 to 950 ° C, Ac 1 to A
c After reheating to the temperature range of 3 transformation point and quenching,
A method for producing a refractory steel material for building structures, which comprises tempering at a temperature of 00 to 650 ° C. However, P CM = C + Si / 30 + Mn / 20
+ Cu / 20 + Ni / 60 + Cr / 20 + Mo / 15 + V / 10 + 5B (%)
Cr:0.10〜0.40％、Ca:0.0005〜0.0050％の内から選ん
だ１種または２種以上を含有する請求項１記載の建築構
造用耐火鋼材の製造方法。2. Cu: 0.05 to 0.40%, Ni: 0.05 to 0.40%,
The method for producing a refractory steel material for a building structure according to claim 1, which contains one or more selected from the group consisting of Cr: 0.10 to 0.40% and Ca: 0.0005 to 0.0050%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12390194A JPH07207336A (en) | 1993-11-30 | 1994-06-06 | Production of refractory steel products for building structural purpose |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5-300099 | 1993-11-30 | ||
| JP30009993 | 1993-11-30 | ||
| JP12390194A JPH07207336A (en) | 1993-11-30 | 1994-06-06 | Production of refractory steel products for building structural purpose |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07207336A true JPH07207336A (en) | 1995-08-08 |
Family
ID=26460693
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12390194A Withdrawn JPH07207336A (en) | 1993-11-30 | 1994-06-06 | Production of refractory steel products for building structural purpose |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07207336A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015163730A (en) * | 2014-01-28 | 2015-09-10 | 株式会社神戸製鋼所 | Low-yield-ratio high-strength steel sheet high in work hardenability and excellent in uniform elongation and weldability and production method thereof |
| CN111926245A (en) * | 2020-07-10 | 2020-11-13 | 南京钢铁股份有限公司 | Thin-specification anti-seismic fire-resistant steel plate with yield strength of 345MPa and preparation method thereof |
-
1994
- 1994-06-06 JP JP12390194A patent/JPH07207336A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015163730A (en) * | 2014-01-28 | 2015-09-10 | 株式会社神戸製鋼所 | Low-yield-ratio high-strength steel sheet high in work hardenability and excellent in uniform elongation and weldability and production method thereof |
| CN111926245A (en) * | 2020-07-10 | 2020-11-13 | 南京钢铁股份有限公司 | Thin-specification anti-seismic fire-resistant steel plate with yield strength of 345MPa and preparation method thereof |
| CN111926245B (en) * | 2020-07-10 | 2022-01-11 | 南京钢铁股份有限公司 | Thin-specification anti-seismic fire-resistant steel plate with yield strength of 345MPa and preparation method thereof |
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