JP2551254B2 - Method for manufacturing structural refractory steel with excellent high-temperature strength properties after reheating - Google Patents
Method for manufacturing structural refractory steel with excellent high-temperature strength properties after reheatingInfo
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- JP2551254B2 JP2551254B2 JP3071696A JP7169691A JP2551254B2 JP 2551254 B2 JP2551254 B2 JP 2551254B2 JP 3071696 A JP3071696 A JP 3071696A JP 7169691 A JP7169691 A JP 7169691A JP 2551254 B2 JP2551254 B2 JP 2551254B2
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Description
【０００１】[0001]
【産業上の利用分野】この発明は、例えば火災等で数時
間程度の短時間、高温状態になることが懸念される建築
物、橋梁等の鉄骨構造物に使用する鋼材の製造方法に関
し、特に、一旦火災等で高温状態になった後での再使用
も可能である再加熱後の高温強度特性に優れた構造用耐
火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 method for manufacturing a steel material for use in a steel structure such as a building or a bridge, which is likely to be in a high temperature state for a short time such as a few hours due to fire or the like. The present invention relates to a method for producing a structural fire-resistant steel material having excellent high-temperature strength properties after reheating, which can be reused once it has been heated to a high temperature.
【０００２】[0002]
【従来技術および発明が解決しようとする課題】通常、
構造用鋼材は常温で十分な所定の強度を有するように製
造されているが、一般に、温度の上昇に伴い強度は低下
する。特に、従来の構造用鋼材は５００℃程度以上の高
温状態では、顕著な強度低下を示すことが、既に、知ら
れている。そのため、火災等で高温状態になることが懸
念される構造物、特に、人間が居住する建築物では、高
温状態でも構造物が倒壊したり、著しく変形することが
ないようにし、さらに、安全性を確保することを目的と
して鋼材の温度が著しく高くならないように耐火被覆が
施されている。PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION
Structural steel materials are manufactured to have a sufficient predetermined strength at room temperature, but generally the strength decreases as the temperature rises. In particular, it has been already known that the conventional structural steel materials show a marked decrease in strength in a high temperature state of about 500 ° C. or higher. Therefore, in structures where there is a risk that the temperature will rise to a high temperature due to a fire, etc., especially in buildings where humans live, prevent the structures from collapsing or deforming significantly even under high temperature conditions. In order to secure the temperature, a fireproof coating is applied so that the temperature of the steel material does not rise significantly.
【０００３】このような現状の耐火に対する対策におい
て、高温状態でも鋼材の強度低下を小さく抑えることが
できれば、耐火被覆の厚さを低減すること、あるいは、
耐火に対してのその他の対策を軽減することが可能にな
る。As a countermeasure against such existing fire resistance, if the strength reduction of the steel material can be suppressed to a small level even at high temperature, the thickness of the fire resistant coating can be reduced, or
It is possible to reduce other measures for fire resistance.
【０００４】高温での強度を保証した鋼材については、
圧力容器用鋼材の分野でその研究が行われてきており、
例えば、日本工業規格（ＪＩＳ）では、ＪＩＳ Ｇ ３
１２４；中・常温圧力容器用高強度鋼鋼板等で既に規格
化されている。また、具体的に規定はしていないが、常
温を超える中・高温での強度が高いことを前提とした圧
力容器用鋼として、例えば、ＪＩＳでは、ＪＩＳ Ｇ
３１１８；中・常温圧力容器用炭素鋼鋼板、ＪＩＳ Ｇ
３１１９；ボイラ及び圧力容器用マンガンモリブデン
鋼及びマンガンモリブデンニッケル鋼鋼板、ＪＩＳ Ｇ
３１２０；圧力容器用調質型マンガンモリブデン鋼及
びマンガンモリブデンニッケル鋼鋼板、ＪＩＳ Ｇ ４
１０９；ボイラ及び圧力容器用クロムモリブデン鋼鋼板
等がある。また、特公告昭６０−３５９８５では圧力容
器用高強度強靭鋼が開示されている。ここで開示されて
いる鋼は、特に高温での特性を規定するまでもなく、圧
力容器用鋼であることで既にある程度の高温強度を前提
としている。Regarding steel materials that guarantee strength at high temperatures,
Research has been conducted in the field of steel for pressure vessels,
For example, in the Japanese Industrial Standard (JIS), JIS G 3
124; It has already been standardized for high-strength steel plates for medium / normal temperature pressure vessels. Further, although not specifically defined, as a steel for a pressure vessel, which is premised on having high strength at medium and high temperatures exceeding room temperature, for example, in JIS, JIS G
3118; Carbon steel plate for medium / normal temperature pressure vessel, JIS G
3119; Manganese molybdenum steel and manganese molybdenum nickel steel plates for boilers and pressure vessels, JIS G
3120; tempered manganese molybdenum steel and manganese molybdenum nickel steel sheet for pressure vessels, JIS G 4
109; chrome molybdenum steel steel plates for boilers and pressure vessels. Further, Japanese Patent Publication No. 60-35985 discloses high strength and toughness steel for pressure vessels. The steel disclosed here is not limited to the characteristics at high temperatures, but is premised to have a certain degree of high-temperature strength as a pressure vessel steel.
【０００５】しかしながら、このような鋼の場合には、
通常、高温強度を高くするために、Ｃｒ，Ｍｏ等の高価
な合金元素を０．５％以上と多量に添加している。する
ことが一般的に行われている。また、ＪＩＳ Ｇ ３１
２４；中・常温圧力容器用高強度鋼鋼板では、比較的合
金元素の添加量は少ないが、高温での強度の規定は、高
々４００℃までである。つまり、４００℃を超えるかな
り高い温度では、十分な強度が得られない。また、これ
らの鋼材は、圧力容器用鋼材を前提としたものであり、
構造用鋼材としては十分な特性を有しているとは言えな
い。さらに、構造物において火災が生じた場合には、鋼
材は一度高温状態になるため、鋼材の特性が変化するこ
とが予想され、火災後も構造物を再使用する場合には、
その部分を取り替える必要が生じる。部材の取り替え
は、当然のことながら経済的な観点から望ましくない。However, in the case of such steel,
Usually, expensive alloy elements such as Cr and Mo are added in a large amount of 0.5% or more in order to increase the high temperature strength. It is generally done. In addition, JIS G 31
24; In the high-strength steel sheet for medium / normal temperature pressure vessels, the amount of alloying elements added is relatively small, but the strength at high temperature is regulated up to 400 ° C. That is, sufficient strength cannot be obtained at a considerably high temperature exceeding 400 ° C. Moreover, these steel materials are premised on steel materials for pressure vessels,
It cannot be said that it has sufficient properties as a structural steel material. Furthermore, when a fire occurs in a structure, the steel material is once in a high temperature state, so it is expected that the characteristics of the steel material will change, and when the structure is reused after the fire,
It becomes necessary to replace that part. Replacement of components is, of course, not desirable from an economical point of view.
【０００６】構造用鋼材で耐火性を付与した鋼材は、特
開平２−７７５２３に開示されているが、ここで開示さ
れた鋼はＭｏ添加量が０．４〜０．７％と高くなってお
り、通常使用されている構造用鋼材としては高合金系成
分になっている。さらに、特開平２−７７５２３では製
造までの高温強度特性に関しては規定しているものの、
一旦火災を生じた後の鋼材の特性に関しては何ら示され
ておらず、高温状態になった後にこの鋼材を再使用する
ことは困難である。[0006] A structural steel material having fire resistance is disclosed in Japanese Patent Application Laid-Open No. 2-77523, but the steel disclosed here has a high Mo addition amount of 0.4 to 0.7%. However, it is a high alloy type component as a structural steel material that is normally used. Furthermore, although Japanese Patent Laid-Open No. 2-77523 stipulates high-temperature strength characteristics up to manufacturing,
There is no indication of the properties of the steel once a fire has occurred, and it is difficult to reuse this steel after it has reached a high temperature.
【０００７】このように、高温での強度を十分に確保
し、さらに、火災等で高温状態になった後でも優れた高
温強度特性を保証でき、再使用にも十分に耐えることの
できる構造用耐火鋼材は、ほとんど開発されていないの
が現状である。すなわち、現状の問題点をまとめると、
以下のようになる。As described above, for a structure which can sufficiently secure the strength at high temperature, can guarantee the excellent high-temperature strength characteristics even after the temperature becomes high due to a fire or the like, and can sufficiently endure the reuse. At present, almost no refractory steel materials have been developed. In other words, to summarize the current problems,
It looks like this:
【０００８】（１）構造用鋼材としての十分な特性（高
溶接性、高延靭性等）を満足しつつ、４００℃程度以上
での高い高温強度を保持した鋼材の製造方法が確立して
いない。 （２）（１）の特性を満足するためには、高
価な合金元素を大量に添加するため、鋼材コストが非常
に高い。（３）一旦高温状態になった後の鋼材の常温・
高温特性が劣化し、再使用できない。(1) A method for producing a steel material that satisfies the sufficient characteristics (high weldability, high ductility and toughness, etc.) as a structural steel material and that maintains high high-temperature strength at about 400 ° C. or higher has not been established. . (2) In order to satisfy the characteristics of (1), a large amount of expensive alloy elements are added, so that the steel material cost is very high. (3) Normal temperature of the steel material once it has reached a high temperature
High temperature characteristics deteriorate and cannot be reused.
【０００９】この発明は、かかる事情に鑑みてなされた
ものであって、高価な合金元素を多量に添加しなくても
高温において高い強度を保持し、かつ、一旦高温状態に
なった後でも良好な高温強度特性を維持し、または向上
させることができ、さらに、従来の構造用鋼材の利点で
ある高溶接性、高い延靭性を有する再加熱後の高温強度
特性に優れた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。The present invention has been made in view of the above circumstances, and retains high strength at high temperatures without adding a large amount of expensive alloying elements, and is good even after once being in a high temperature state. Of high-strength structural fire-resistant steel that has excellent weldability and ductility, which are advantages of conventional structural steels, and excellent high-temperature strength characteristics after reheating. It is intended to provide a manufacturing method.
【００１０】[0010]
【課題を解決するための手段】この発明は、上記目的を
達成するために、重量％表示で、 Ｃ：０．０５％以上、０．２０％未満 Ｓｉ：０．１％以上、２．０％未満 Ｍｎ：０．３％以上、２．０％未満 Ｐ：０．０３％以下 Ｓ：０．０３％以下 Ｍｏ：０．１％以上、０．４％未満 Ｔｉ：０．００３％以上、０．１％未満 Ｖ：０．０１％以上０．１％未満 ｓｏｌ．Ａｌ：０．００２％以上、０．２％未満 Ｎ：０．００１０％以上、０．０２０％未満The present invention, in order to achieve the above object, is expressed in weight%, C: 0.05% or more and less than 0.20% Si: 0.1% or more, 2.0 % Less Mn: 0.3% or more, less than 2.0% P: 0.03% or less S: 0.03% or less Mo: 0.1% or more, less than 0.4% Ti: 0.003% or more, Less than 0.1% V: 0.01% or more and less than 0.1% sol. Al: 0.002% or more, less than 0.2% N: 0.0010% or more, less than 0.020%
【００１１】を含み、残部がＦｅおよび不可避不純物か
らなる鋼を１０００〜１３５０℃に加熱し、これを熱間
圧延する際に、９００℃以上の温度において圧下率を３
０％以上とし、仕上げ温度をＡｒ3 −１００℃〜Ａｒ3
＋１００℃とした後、冷却速度２〜２０℃／秒で強制的
に冷却し、４００〜６００℃で冷却を停止し、空冷する
ことを特徴とする再加熱後の高温強度特性に優れた構造
用耐火鋼材の製造方法を提供する。この発明は、また、
上記組成の鋼に、さらに、 Ｃｕ：０．０１％以上、１．５％未満 Ｎｉ：０．０２％以上、１．５％未満 Ｂ：０．０００５％以上、０．００５％未満 Ｎｂ：０．００５％以上、０．０５％未満When the steel containing Fe and the unavoidable impurities as the balance is heated to 1000 to 1350 ° C. and hot-rolled, a reduction rate of 3 at a temperature of 900 ° C. or higher.
0% or more, finishing temperature Ar 3 -100 ℃ ~ Ar 3
After having been set to + 100 ° C, it is forcibly cooled at a cooling rate of 2 to 20 ° C / sec, stopped at 400 to 600 ° C, and air-cooled. A method for manufacturing a refractory steel material is provided. This invention also
In addition to the above composition of steel, Cu: 0.01% or more and less than 1.5% Ni: 0.02% or more and less than 1.5% B: 0.0005% or more, less than 0.005% Nb: 0 0.005% or more, less than 0.05%
【００１２】のうち１種または２種以上を含む鋼に対し
て、上記工程と同様の工程を施すことを特徴とする再加
熱後の高温強度特性に優れた構造用耐火鋼材の製造方法
を提供する。この場合に、必要に応じて、冷却停止後、
７００℃以下に際加熱してから空冷することもできる。A method for producing a structural refractory steel material having excellent high-temperature strength properties after reheating, characterized in that a step similar to the above step is performed on steel containing one or more of the above To do. In this case, if necessary, after stopping cooling,
It is also possible to heat up to 700 ° C. or less and then cool with air.
【００１３】本発明において、最も重要な点は、溶接
性、コスト等を考慮した上で、鋼材を製造した状態にお
いて十分に高い高温強度特性を有しているとともに、一
旦、高温状態になった後でも十分な常温・高温強度特性
を保持していることである。このようなことを考慮し
て、、本願発明者等が上記課題を解決するために鋭意検
討した結果、主としてＭｏ，Ｖ，Ｔｉを複合添加した鋼
に対して特定条件の熱間圧延を施すことにより、十分に
高い高温強度特性を付与することができ、かつ再加熱後
の常温・高温強度特性を十分に高いものとすることがで
きることを見出した。上記内容の本発明は、このような
本願発明者等の知見に基づいてなされたものである。次
に、各添加元素の含有量の限定理由を示す。In the present invention, the most important point is that, in consideration of weldability, cost, etc., the steel material has sufficiently high high-temperature strength characteristics in a manufactured state, and once it is in a high-temperature state. That is, it retains sufficient room temperature / high temperature strength properties even afterwards. In view of the above, the inventors of the present application have conducted extensive studies to solve the above-mentioned problems, and as a result, mainly hot-rolling steel containing composite addition of Mo, V, and Ti under specific conditions. As a result, it was found that a sufficiently high temperature strength property can be imparted and the room temperature / high temperature strength property after reheating can be made sufficiently high. The present invention having the above contents is made based on the findings of the inventors of the present application. Next, the reasons for limiting the content of each additive element will be shown.
【００１４】Ｃ： Ｃは鋼の常温強度、高温強度を安定
して確保するための有効な元素である。しかし、０．０
５％未満では、所定の十分な強度を得るのが困難であ
り、また、０．２０％以上では溶接性が劣化する。この
ため、Ｃの含有量を０．０５％以上０．２０％未満に規
定する。C: C is an effective element for stably ensuring the room temperature strength and high temperature strength of steel. But 0.0
If it is less than 5%, it is difficult to obtain a predetermined sufficient strength, and if it is 0.20% or more, the weldability deteriorates. Therefore, the content of C is specified to be 0.05% or more and less than 0.20%.
【００１５】Ｓｉ： Ｓｉは脱酸元素として有効な元素
であり少なくとも０．１％以上の添加が必要である。ま
た、Ｓｉは固溶強化に対して有効な元素であるが、２．
０％以上の添加量では延靭性が低下したり、介在物が増
加する等の問題がある。このため、Ｓｉの含有量を０．
１％以上２．０％未満に規定する。Si: Si is an element effective as a deoxidizing element, and it is necessary to add at least 0.1%. Further, Si is an element effective for solid solution strengthening, but 2.
If the addition amount is 0% or more, there are problems such as reduction in ductility and increase in inclusions. Therefore, the Si content is set to 0.
It is specified to be 1% or more and less than 2.0%.
【００１６】Ｍｎ： Ｍｎは強度確保の上で有効な元素
であり、そのためには０．３％以上の添加が必要であ
る。また、２．０％以上では溶接性が劣化する。このた
め、Ｍｎの含有量を０．３％以上２．０％未満に規定す
る。Mn: Mn is an element effective in securing strength, and for that purpose, 0.3% or more is required to be added. If it is 2.0% or more, the weldability is deteriorated. Therefore, the Mn content is specified to be 0.3% or more and less than 2.0%.
【００１７】Ｐ，Ｓ： Ｐ，Ｓは不純物元素であり、延
靭性の低下、加工性、溶接性の低下等の問題の原因とな
るため、できるだけ少なくすることが望ましい。しかし
ながら、著しく低減するとコストの上昇を招く。このた
め、これらの含有量を、コストの上昇を招かず、しかも
顕著な材質劣化を生じない範囲である０．０３％以下に
規定する。P, S: P and S are impurity elements and cause problems such as deterioration in ductility, workability, and weldability, so it is desirable to minimize them. However, if it is significantly reduced, the cost will increase. For this reason, the content of these is specified to be 0.03% or less, which is a range in which the cost is not increased and the material is not significantly deteriorated.
【００１８】Ｍｏ： Ｍｏは焼入性の向上、析出強化等
により鋼の強度を上昇させる有効な元素であり、特に、
中・高温強度に対しては有効である。しかし、０．１％
未満ではその効果を得ることが困難であり、また、０．
４％以上の多量添加はコスト上昇になる上に溶接性も劣
化させる。このため、Ｍｏの含有量を０．１％以上０．
４％未満に規定する。Mo: Mo is an effective element for increasing the strength of steel by improving hardenability, precipitation strengthening, etc.
It is effective for medium and high temperature strength. However, 0.1%
If it is less than 1, it is difficult to obtain the effect, and if it is 0.
Addition of a large amount of 4% or more not only raises the cost but also deteriorates the weldability. Therefore, the content of Mo is 0.1% or more and 0.1.
Specify less than 4%.
【００１９】Ｖ： Ｖは微量添加でも高温強度上昇に対
して有効であるだけでなく、再加熱後の常温・高温強度
特性改善に有効な元素である。しかし、０．０１％未満
ではこのような効果が得られず、また、０．１％以上の
多量添加は溶接性を劣化させるとともにコスト上昇にな
る。このため、Ｖの含有量を０．０１％以上０．１％未
満に規定する。V: V is an element which is effective not only for increasing the high temperature strength even when added in a small amount, but also for improving the room temperature / high temperature strength characteristics after reheating. However, if it is less than 0.01%, such an effect cannot be obtained, and addition of a large amount of 0.1% or more deteriorates the weldability and increases the cost. Therefore, the V content is specified to be 0.01% or more and less than 0.1%.
【００２０】Ｔｉ： ＴｉはＴｉＮを形成しオーステナ
イト粒を微細化する効果があり、靭性向上に有効である
とともに、固溶Ｔｉは高温状態でＴｉＣを形成し、高温
強度も上昇させ、さらに、再加熱後の常温・高温強度靭
性も改善する。しかし、０．００３％未満ではこれらの
効果が得られず、また、０．１％以上の大量添加は溶接
性を劣化させる。このため、Ｔｉの含有量を０．００３
％以上０．１％未満に規定する。Ti: Ti has the effect of forming TiN and refining the austenite grains, and is effective in improving toughness, while solid solution Ti forms TiC in a high temperature state and also increases high temperature strength. Improves room temperature / high temperature strength and toughness after heating. However, if less than 0.003%, these effects cannot be obtained, and addition of a large amount of 0.1% or more deteriorates weldability. Therefore, the Ti content is 0.003
% Or more and less than 0.1%.
【００２１】ｓｏｌ．Ａｌ： ｓｏｌ．ＡｌはＡｌＮと
して鋼中に析出し、結晶粒の微細化に有効な元素であ
る。しかし、０．００２％未満ではその効果が得られ
ず、また、０．２％以上の添加では酸化物系の介在物が
多くなり、延靭性が劣化する。このため、ｓｏｌ．Ａｌ
の含有量を０．００２％以上０．２％未満に規定する。Sol. Al: sol. Al is an element that precipitates in the steel as AlN and is effective in refining the crystal grains. However, if it is less than 0.002%, the effect cannot be obtained, and if it is added in an amount of 0.2% or more, oxide-based inclusions increase, and ductility deteriorates. Therefore, sol. Al
Content of 0.002% or more and less than 0.2%.
【００２２】Ｎ： ＮはＡｌＮまたはＴｉＮを析出させ
る元素であり、結晶粒の微細化に有効である。しかし、
０．００１０％未満ではその効果が得られず、また、
０．０２０％以上の多量添加では溶接部の靭性が劣化す
る。このため、Ｎの含有量を０．００１０％以上０．０
２０％未満に規定する。N: N is an element for precipitating AlN or TiN, and is effective for refining crystal grains. But,
If less than 0.0010%, the effect cannot be obtained, and
If a large amount of 0.020% or more is added, the toughness of the welded portion deteriorates. Therefore, the content of N is 0.0010% or more and 0.0
Specify less than 20%.
【００２３】Ｎｂ： Ｎｂは常温強度に有効な上に高温
強度の上昇に対しても有効な元素である。しかし、０．
００５％未満ではその効果が得られず、また、０．０５
％を超えて添加すると溶接部の靭性が劣化する。このた
め、Ｎｂの含有量を０．００５％以上０．０５％未満に
規定する。Nb: Nb is an element effective not only in strength at room temperature but also in strength at high temperature. However, 0.
If it is less than 005%, the effect cannot be obtained.
%, The toughness of the weld will deteriorate. Therefore, the Nb content is specified to be 0.005% or more and less than 0.05%.
【００２４】Ｃｕ： Ｃｕは固溶強化に有効な元素であ
り、また１％程度以上では析出強化も期待できる元素で
ある。また、耐腐食性に対しても有効である。しかし、
０．０１％未満ではその効果が得られず、また１．５％
以上の添加はコスト上昇に加えて鋼板の表面キズの問題
がある。このため、Ｃｕ含有量を０．０１％以上１．５
％未満に規定する。Cu: Cu is an element effective for solid solution strengthening, and at about 1% or more, precipitation strengthening can be expected. It is also effective for corrosion resistance. But,
If it is less than 0.01%, the effect cannot be obtained, and it is 1.5%.
In addition to the cost increase, the above additions have a problem of surface scratches on the steel sheet. Therefore, the Cu content is 0.01% or more and 1.5
Specify less than%.
【００２５】Ｎｉ： Ｎｉは低温靭性の向上に有効な元
素である。しかし、０．０２％未満ではその効果は小さ
く、また、Ｎｉは高価であるため１．５％以上ではコス
ト上昇が著しい。このため、Ｎｉ含有量を０．０２％以
上１．５％未満に規定する。Ni: Ni is an element effective in improving low temperature toughness. However, if it is less than 0.02%, its effect is small, and since Ni is expensive, if it is 1.5% or more, the cost rises significantly. Therefore, the Ni content is specified to be 0.02% or more and less than 1.5%.
【００２６】[0026]
【００２７】Ｂ： Ｂは微量添加で鋼の焼入性を上昇さ
せる有効な元素であり、０．０００５％以上であれば十
分にその効果を示す。また、０．００５％以上では、焼
入性向上効果も小さくなるとともに、溶接性を劣化させ
る。このため、Ｂの含有量を０．０００５％以上０．０
０５％未満に規定する。次に、製造プロセスについて説
明する。B: B is an effective element that increases the hardenability of steel by adding a trace amount, and if it is 0.0005% or more, the effect is sufficiently exhibited. Further, if it is 0.005% or more, the effect of improving the hardenability becomes small and the weldability deteriorates. Therefore, the content of B is 0.0005% or more and 0.0
Specify less than 05%. Next, the manufacturing process will be described.
【００２８】まず、上述の成分組成の鋼を１０００〜１
３５０℃に加熱する。これは、加熱温度が１０００℃未
満では所定の圧延終了温度を確保することが困難である
と共に、圧延に伴う歪等が著しくなり、逆に１３５０℃
を超えると加熱コストが顕著に増大するためである。First, 1000 to 1 of the steel having the above-mentioned chemical composition is used.
Heat to 350 ° C. This is because if the heating temperature is less than 1000 ° C., it is difficult to secure a predetermined rolling end temperature, and distortion and the like due to rolling become significant, and conversely 1350 ° C.
This is because the heating cost remarkably increases when the value exceeds.
【００２９】次いで、熱間圧延を施す。この場合に、所
望の特性を得るためにはオーステナイト結晶粒の微細化
を図る必要があるが、そのためにオーステナイト再結晶
域での加工を十分に行う必要があり、少なくとも３０％
以上の加工が必要である。この観点から、熱間圧延条件
を、オーステナイト再結晶域である９００℃以上の温度
域において圧下率を３０％以上とした。Then, hot rolling is performed. In this case, in order to obtain the desired characteristics, it is necessary to refine the austenite crystal grains, but for that purpose, it is necessary to sufficiently process the austenite recrystallization region, and at least 30%.
The above processing is required. From this point of view, the hot rolling conditions were such that the rolling reduction was 30% or more in the temperature range of 900 ° C. or higher which is the austenite recrystallization region.
【００３０】圧延仕上げ温度がＡｒ3 〜Ａｒ3 −１００
℃の範囲では二相域圧延となり、強度が上昇する効果が
あるが、Ａｒ3 −１００℃未満では圧延後の強制冷却に
よる強度上昇効果が小さくなると共に、鋼材の特性の異
方性が顕著になる。また、Ａｒ3 〜Ａｒ3 ＋１００℃の
範囲では、未再結晶域での圧延効果により結晶粒径が微
細化する効果があると共に、強制冷却による強度上昇効
果が明確であるが、Ａｒ3 ＋１００℃を超える温度で
は、強制冷却による効果はあるものの、結晶粒径が粗大
であるため、延靱性が著しく低下する。このため、仕上
げ温度をＡｒ3−１００℃〜Ａｒ3 ＋１００℃の範囲と
した。The rolling finishing temperature is Ar 3 to Ar 3 -100.
In the range of ℃, it becomes a two-phase region rolling and there is an effect of increasing the strength, but if it is less than Ar 3 -100 ℃, the effect of increasing the strength by the forced cooling after rolling becomes small, and the anisotropy of the properties of the steel material becomes remarkable Become. Further, in the range of Ar 3 to Ar 3 + 100 ° C., the rolling effect in the unrecrystallized region has the effect of making the crystal grain size fine, and the strength-increasing effect by forced cooling is clear, but Ar 3 + 100 ° C. If the temperature exceeds 1, the effect of forced cooling is obtained, but since the crystal grain size is coarse, the ductility and toughness is remarkably reduced. Therefore, the finishing temperature is set in the range of Ar 3 -100 ° C to Ar 3 + 100 ° C.
【００３１】その後の強制冷却は、上述したように、強
度上昇効果を付与するものであるが、その冷却速度が２
〜２０℃／秒から外れると、所望の効果が得られない。
しかし、４００〜６００℃に至った後は、空冷しても何
等差支えない。The subsequent forced cooling imparts the strength increasing effect as described above, but the cooling rate is 2
If it deviates from -20 ° C / sec, the desired effect cannot be obtained.
However, after reaching 400 to 600 ° C, there is no problem even if air cooling is performed.
【００３２】なお、熱間圧延後に生じた歪等の除去及び
切断後に発生する歪の防止等の観点から、必要に応じ
て、強制冷却後７００℃以下の温度に加熱してから空冷
してもよい。７００℃以下としたのは、７００℃を超え
ると部分的に二相域に加熱される可能性があり材質が著
しく変化するからである。From the viewpoints of removing strains generated after hot rolling and preventing strains generated after cutting, if necessary, even after forced cooling, heating to a temperature of 700 ° C. or lower and then air cooling are performed. Good. The reason why the temperature is 700 ° C. or lower is that, if the temperature exceeds 700 ° C., the material may be remarkably changed since the material may be partially heated in the two-phase region.
【００３３】[0033]
【実施例】以下、この発明の実施例について説明する。Embodiments of the present invention will be described below.
【００３４】表１に供試鋼に化学成分およびＡｒ3 温度
を示す。符号Ａ〜Ｄの鋼は本発明の範囲内の成分・組成
のものであり、符号Ｅ，Ｆは本発明の成分・組成から外
れる比較鋼である。比較鋼Ｅは本発明で必須元素である
Ｖが添加されておらず、Ｃｒが添加されている。同様
に、比較鋼Ｆは本発明鋼Ａの比較であり、この比較鋼Ｆ
にもやはりＶが添加されておらず、本発明の範囲外にな
っている。Table 1 shows the chemical composition and Ar 3 temperature of the test steel. Steels A to D are components and compositions within the scope of the present invention, and reference symbols E and F are comparative steels that deviate from the components and compositions of the present invention. Comparative Steel E does not include V, which is an essential element in the present invention, but does include Cr. Similarly, Comparative Steel F is a comparison of Invention Steel A, and Comparative Steel F
Again, V was not added, which is outside the scope of the present invention.
【００３５】表２に供試鋼Ａ〜Ｆを用いて製造した鋼板
（板厚４０mm）の製造条件および常温引張試験、高温引
張試験結果を示す。高温引張試験に関しては、製造まま
材で実施するとともに、６００℃に再加熱した鋼材につ
いても実施した。表２において、符号の頭に示されたア
ルファベットは表１のＡ〜Ｈに対応し、例えばＡ−１と
表記してある場合は、表１に示した鋼Ａを用いたことを
示す。符号Ａ−１〜Ｄは本発明の範囲内の成分・組成、
および製造条件を満足する実施例であり、符号Ｅ−１〜
Ｆはこれらの範囲から外れる比較例である。Table 2 shows the manufacturing conditions and the room temperature tensile test and high temperature tensile test results of the steel plates (plate thickness 40 mm) manufactured using the test steels A to F. The high temperature tensile test was performed not only on the as-manufactured material but also on the steel material reheated to 600 ° C. In Table 2, the alphabets shown at the beginning of the reference numerals correspond to A to H in Table 1, and for example, when written as A-1, it indicates that the steel A shown in Table 1 was used. Reference symbols A-1 to D are components and compositions within the scope of the present invention,
And an embodiment satisfying the manufacturing conditions, and reference symbols E-1 to
F is a comparative example out of these ranges.
【００３６】表２から明らかなように、実施例の場合に
は、圧延ままでも、熱処理後においても、再加熱後の高
温降伏強度（ＹＳ）が製造ままの高温降伏強度よりも２
〜３kgf/mm2 程度以上上昇している。この結果から、本
発明の範囲内であれば、火災を想定した再加熱処理後の
高温強度特性が優れていることが確認された。As is clear from Table 2, in the case of Examples, the high-temperature yield strength (YS) after reheating is 2% higher than the as-manufactured high-temperature yield strength, both as rolled and after heat treatment.
~ 3kgf / mm 2 It has risen more than about a degree. From this result, it was confirmed that, within the range of the present invention, the high temperature strength characteristics after the reheating treatment assuming a fire were excellent.
【００３７】比較例のＥ−１〜２は、製造条件が本発明
の範囲内であるが、表１に示したように、成分・組成が
本発明の範囲外であるため、製造ままの常温強度、高温
強度が同等程度であるのにもかかわらず、再加熱後の高
温強度が著しく低下しており、本発明の目的としている
再加熱後の良好な高温強度特性が得られていない。同様
に、比較例Ｆは対応する実施例Ａ−１に比較して、製造
ままの常温・高温強度は同等水準であるが、再加熱後の
高温強度は低下しており、本発明の目的を満足していな
いことが確認された。In the comparative examples E-1 and E-2 , the production conditions are within the scope of the present invention, but as shown in Table 1, the components and compositions are outside the scope of the present invention, so that they are at the room temperature as produced. Although the strength and the high temperature strength are about the same, the high temperature strength after reheating is remarkably reduced, and the good high temperature strength characteristics after reheating, which is the object of the present invention, are not obtained. Similarly, in Comparative Example F, as compared with the corresponding Example A-1, the as-manufactured room-temperature / high-temperature strength is at the same level, but the high-temperature strength after reheating is reduced, and the purpose of the present invention is to It was confirmed that they were not satisfied.
【００３８】このように、本発明の範囲内の成分・組成
および製造条件の鋼では６００℃程度における高温強度
特性に優れているとともに、火災後の再使用を考慮した
場合でも、再加熱後の高温強度はむしろ上昇し、構造用
耐火鋼材として優れた特性を有していることが確認され
た。As described above, the steel having the components / compositions and the manufacturing conditions within the scope of the present invention has excellent high temperature strength characteristics at about 600 ° C. and, even when considering reuse after a fire, after being reheated. It was confirmed that the high temperature strength was rather increased and that it had excellent properties as a structural refractory steel material.
【００３９】[0039]
【発明の効果】この発明によれば、高価な合金元素を多
量に添加しなくても高温において高い強度を保持し、か
つ、一旦高温状態になった後でも良好な高温強度特性を
維持し、または向上させることができ、さらに、従来の
構造用鋼材の利点である高溶接性、高い延靭性を有する
再加熱後の高温強度特性に優れた構造用耐火鋼材の製造
方法が提供される。このため、従来、耐火特性を要求さ
れていた構造物で当然使用されていた耐火被覆の厚さを
低減あるいは設計・施工法の簡便化が期待できるととも
に、その他の耐火に対する対策も軽減できる等の効果が
ある。According to the present invention, high strength can be maintained at high temperature without adding a large amount of expensive alloying elements, and good high temperature strength characteristics can be maintained even after once becoming high temperature. Further, there is provided a method for producing a structural refractory steel having excellent weldability and high ductility, which are advantages of conventional structural steels, and excellent in high temperature strength characteristics after reheating. For this reason, it is expected that the thickness of the fireproof coating, which was naturally used in the structure that has conventionally been required to have fireproof properties, can be reduced or the design and construction method can be simplified, and that measures for other fireproof can be reduced. effective.
【００４０】[0040]
【表１】 [Table 1]
【００４１】[0041]
【表２】 [Table 2]
───────────────────────────────────────────────────── フロントページの続き (72)発明者 石川 博 東京都千代田区丸の内一丁目１番２号 日本鋼管株式会社内 (72)発明者 畠山 耕太郎 東京都千代田区丸の内一丁目１番２号 日本鋼管株式会社内 (56)参考文献 特開 平３−39418（ＪＰ，Ａ) ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiroshi Ishikawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Co., Ltd. (72) Kotaro Hatakeyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Steel Tube Within the corporation (56) References JP-A-3-39418 (JP, A)
Claims (4)
０００〜１３５０℃に加熱し、これを熱間圧延する際
に、９００℃以上の温度において圧下率を３０％以上と
し、仕上げ温度をＡｒ3 −１００℃〜Ａｒ3 ＋１００℃
とした後、冷却速度２〜２０℃／秒で強制的に冷却し、
４００〜６００℃で冷却を停止し、空冷することを特徴
とする再加熱後の高温強度特性に優れた構造用耐火鋼材
の製造方法。1. In% by weight, C: 0.05% or more and less than 0.20% Si: 0.1% or more and less than 2.0% Mn: 0.3% or more, less than 2.0% P : 0.03% or less S: 0.03% or less Mo: 0.1% or more and less than 0.4% Ti: 0.003% or more and less than 0.1% V: 0.01% or more, 0.1 Less than% sol. Al: 0.002% or more, less than 0.2% N: 0.0010% or more, less than 0.020%, with the balance being Fe and inevitable impurities 1
When heated to 000 to 1350 ° C. and hot-rolled, the reduction rate is set to 30% or more at a temperature of 900 ° C. or more, and the finishing temperature is Ar 3 −100 ° C. to Ar 3 + 100 ° C.
And then forcibly cool at a cooling rate of 2 to 20 ° C./second,
A method for producing a structural refractory steel material having excellent high-temperature strength characteristics after reheating, which comprises cooling at 400 to 600 ° C. and air cooling.
し空冷することを特徴とする請求項１に記載の再加熱後
の高温強度特性に優れた製造用耐火鋼材の構造方法。2. The method for constructing a refractory steel material for production having excellent high-temperature strength properties after reheating according to claim 1, wherein after cooling is stopped, it is heated to 700 ° C. or less and air-cooled.
可避不純物からなる鋼を１０００〜１３５０℃に加熱
し、これを熱間圧延する際に、９００℃以上の温度にお
いて圧下率を３０％以上とし、仕上げ温度をＡｒ3 −１
００℃〜Ａｒ3 ＋１００℃とした後、冷却速度２〜２０
℃／秒で強制的に冷却し、４００〜６００℃で冷却を停
止し、空冷することを特徴とする再加熱後の高温強度特
性に優れた構造用耐火鋼材の製造方法。3. In% by weight, C: 0.05% or more and less than 0.20% Si: 0.1% or more and less than 2.0% Mn: 0.3% or more and less than 2.0% P : 0.03% or less S: 0.03% or less Mo: 0.1% or more and less than 0.4% Ti: 0.003% or more and less than 0.1% V: 0.01% or more, 0.1 Less than% sol. Al: 0.002% or more, less than 0.2% N: 0.0010% or more, less than 0.020% included Cu: 0.01% or more, less than 1.5% Ni: 0.02% or more , Less than 1.5% B: 0.0005% or more, less than 0.005% Nb: 0.005% or more, less than 0.05% Contains one or more of the following, with the balance being Fe and inevitable impurities. When the steel is heated to 1000 to 1350 ° C. and hot-rolled, the reduction ratio is set to 30% or more at the temperature of 900 ° C. or more, and the finishing temperature is Ar 3 −1.
After setting the temperature to 00 ° C to Ar 3 + 100 ° C, the cooling rate is 2 to 20
A method for producing a structural refractory steel material having excellent high-temperature strength characteristics after reheating, which comprises forcibly cooling at a temperature of C / sec, stopping cooling at a temperature of 400 to 600 ° C, and cooling by air.
し空冷することを特徴とする請求項３に記載の再加熱後
の高温強度特性に優れた製造用耐火鋼材の構造方法。4. The method for constructing a refractory steel material for production having excellent high-temperature strength properties after reheating according to claim 3, wherein after the cooling is stopped, it is heated to 700 ° C. or less and air-cooled.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3071696A JP2551254B2 (en) | 1991-04-04 | 1991-04-04 | Method for manufacturing structural refractory steel with excellent high-temperature strength properties after reheating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3071696A JP2551254B2 (en) | 1991-04-04 | 1991-04-04 | Method for manufacturing structural refractory steel with excellent high-temperature strength properties after reheating |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04308033A JPH04308033A (en) | 1992-10-30 |
| JP2551254B2 true JP2551254B2 (en) | 1996-11-06 |
Family
ID=13467969
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3071696A Expired - Fee Related JP2551254B2 (en) | 1991-04-04 | 1991-04-04 | Method for manufacturing structural refractory steel with excellent high-temperature strength properties after reheating |
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| Country | Link |
|---|---|
| JP (1) | JP2551254B2 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0788554B2 (en) * | 1988-12-23 | 1995-09-27 | 日本鋼管株式会社 | Fireproof steel for construction |
| JP2830091B2 (en) * | 1989-07-04 | 1998-12-02 | 住友金属工業株式会社 | Method for producing steel for building steel with low elastic modulus reduction at high temperature |
-
1991
- 1991-04-04 JP JP3071696A patent/JP2551254B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04308033A (en) | 1992-10-30 |
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