JP3060635B2 - Manufacturing method of steel for high strength rebar - Google Patents
Manufacturing method of steel for high strength rebarInfo
- Publication number
- JP3060635B2 JP3060635B2 JP3223237A JP22323791A JP3060635B2 JP 3060635 B2 JP3060635 B2 JP 3060635B2 JP 3223237 A JP3223237 A JP 3223237A JP 22323791 A JP22323791 A JP 22323791A JP 3060635 B2 JP3060635 B2 JP 3060635B2
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- strength
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Description
【０００１】[0001]
【産業上の利用分野】この発明は、高強度、とくに下降
伏点が７８０ＭＰａ以上の高強度を有し、かつ、降伏伸
びが大きい鉄筋用鋼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 producing steel for reinforcing steel having high strength, in particular, high strength having a yield point of not less than 780 MPa and high yield elongation.
【０００２】[0002]
【従来の技術】鉄筋コンクリ−ト用棒鋼は、ＪＩＳ Ｇ
３１１２に規定されているように、最大強度のものでも
降伏点が４９０〜６３０ＭＰａ（ＳＤ４９０）である。
このような棒鋼は、Ｃ−Ｍｎ鋼を熱間圧延して製造され
る。2. Description of the Related Art Steel bars for reinforced concrete are JIS G
As specified in 3112, the yield point is 490 to 630 MPa (SD490) even with the highest strength.
Such a steel bar is manufactured by hot rolling C-Mn steel.
【０００３】近時、鉄筋コンクリ−トを用いて造られた
建築物はますます高層化する傾向にあり、鉄筋をさらに
高強度化する要望が高い。ところが、一般に、棒鋼を高
強度化すると、図１に示すように、降伏伸び（εP ／ε
Y）が逆に低下するという不都合を生じる。因みに、建
設省のＮｅｗＲＣ総合プロジェクトの指針によれば、降
伏点が６９０ＭＰａ以上の等級の棒鋼では降伏伸び値が
４％以上であることが好ましいとされているのに対し
て、降伏点が７８０ＭＰａ以上の等級の棒鋼では、特に
降伏伸びは規定されていない。しかしながら、将来、降
伏点が７８０ＭＰａ以上の等級の棒鋼においても、大き
な降伏伸びを要求されることが予想される。[0003] In recent years, buildings made using reinforced concrete tend to be even higher in height, and there is a high demand for further strengthening of reinforcing bars. However, in general, when the strength of a steel bar is increased, as shown in FIG. 1, the yield elongation (ε P / ε
Y ) is disadvantageously reduced. Incidentally, according to the guidelines of the NewRC Comprehensive Project of the Ministry of Construction, it is preferable that the yield elongation value is 4% or more in the bar having a yield point of 690 MPa or more, whereas the yield point is 780 MPa or more. No specific elongation is specified for steel bars of grade No. However, in the future, it is expected that a large yield elongation will be required even for a bar having a yield point of 780 MPa or more.
【０００４】特公昭６３−６４４９４号公報には、棒鋼
を高強度化するためにＮｂ含有鋼あるいはＮｂ−Ｖ含有
鋼を素材に用い、降伏伸びの低下を抑制するためにこれ
を所定の圧延条件下で制御圧延する製造技術が記載され
ている。また、特公昭６４−１１７０５号公報には、Ｎ
ｂ，Ｖ，Ｃａを添加することにより高強度の鉄筋用鋼と
する技術が記載されている。Japanese Patent Publication No. 63-64494 discloses that an Nb-containing steel or an Nb-V-containing steel is used as a material for enhancing the strength of a steel bar, and to reduce the yield elongation under a predetermined rolling condition. The production technique for controlled rolling below is described. Japanese Patent Publication No. 64-11705 discloses N
A technique is described in which b, V, and Ca are added to make high-strength steel for reinforcing steel.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、これら
の従来の製造方法は、降伏点が４９０〜５９０ＭＰａク
ラスの比較的低強度の棒鋼を対象としており、降伏点が
これらを超える高強度の棒鋼を対象とするものではな
い。すなわち、これらの製造技術においても、棒鋼の降
伏伸びを大きくしようとすると、降伏点が低下する。こ
のため、７８０ＭＰａ以上の降伏点を示す高強度かつ高
降伏伸びの棒鋼を製造することができないでいた。However, these conventional manufacturing methods are intended for relatively low-strength steel bars having a yield point of 490-590 MPa class, and for high-strength steel bars having a yield point exceeding these. It does not mean that. That is, even in these manufacturing techniques, if the yield elongation of the steel bar is to be increased, the yield point decreases. For this reason, it was not possible to produce a high-strength and high-yield elongation steel bar exhibiting a yield point of 780 MPa or more.
【０００６】また、素材を熱処理すれば、このような高
強度・高降伏伸びの特性を得ることはできるが、熱処理
工程を経るために製造コストが上昇するという不都合が
ある。本発明は、かかる事情に鑑みてなされたものであ
って、高強度かつ降伏伸びが大きい鉄筋用鋼の製造方法
を提供することを目的とする。Further, if the material is heat-treated, such high strength and high yield elongation characteristics can be obtained, but there is a disadvantage that the production cost increases due to the heat treatment step. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a steel for reinforcing steel having high strength and large yield elongation.
【０００７】[0007]
【課題を解決するための手段および作用】本発明者ら
は、高強度鉄筋用鋼を得るために、鋭意研究した結果、
バナジウムを多量添加すると強度の増大化がみられるこ
と、および、圧延終了温度の低下による降伏点の出現に
加えて、チタンを有効利用することにより降伏伸びが増
加することを見出した。The present inventors have conducted intensive studies to obtain high-strength steel for reinforcing steel.
It was found that when a large amount of vanadium was added, the strength was increased, and in addition to the appearance of a yield point due to a decrease in the rolling end temperature, the yield elongation was increased by effectively utilizing titanium.
【０００８】[0008]
【０００９】この発明に係る高強度鉄筋用鋼の製造方法
は、Ｃを０．３５〜０．５０質量％，Ｓｉを１．５質量
％以下，Ｍｎを１．７質量％以下，Ｖを０．４〜０．７
質量％，Ｔｉを０．０１〜０．１０質量％，Ｎを０．０
０４〜０．０１質量％それぞれ含有し、残部がＦｅ及び
不可避的不純物からなる素材を、圧延終了温度が６５０
〜９００℃となるように圧延することを特徴とする。素
材の組成をこのような成分範囲とした理由について、各
成分元素ごとに説明する。The method for producing high-strength rebar steel according to the present invention is characterized in that C is 0.35 to 0.50% by mass , Si is 1.5% by mass or less, Mn is 1.7% by mass or less, and V is 0%. 0.4-0.7
% By mass , 0.01 to 0.10% by mass of Ti, and 0.0
A raw material containing 0.4 to 0.01% by mass and the balance consisting of Fe and inevitable impurities having a rolling end temperature of 650.
It is rolled so as to reach 900 ° C. The reason for setting the composition of the material to such a component range will be described for each component element.
【００１０】Ｃは、高強度化に必要な元素であり、所望
の強度レベルを得るには含有量を０．３５重量％以上と
する必要がある。しかし、Ｃ含有量が０．５０重量％を
超えると、降伏点が出現しにくくなるか、または、降伏
点が出現したとしても降伏伸びが小さくなるので、上限
値を０．５０重量％とする。[0010] C is an element necessary for increasing the strength, and its content must be 0.35% by weight or more in order to obtain a desired strength level. However, when the C content exceeds 0.50% by weight, the yield point becomes difficult to appear, or even if the yield point appears, the yield elongation becomes small. Therefore, the upper limit is set to 0.50% by weight. .
【００１１】Ｓｉは、脱酸に必要な元素であり、マトリ
ックスに固溶して強度を増大するのに有効である。しか
し、Ｓｉ含有量が１．５重量％を超えると、靭性が低下
するので、上限値を１．５重量％とする。Si is an element necessary for deoxidation, and is effective for forming a solid solution in a matrix to increase the strength. However, if the Si content exceeds 1.5% by weight, the toughness decreases, so the upper limit is set to 1.5% by weight.
【００１２】Ｍｎは、高強度化に必要な元素である。し
かし、Ｍｎ含有量が１．７重量％を超えると、ベイナイ
ト組織を生じて降伏点が出現しなくなるので、上限値を
１．７重量％とする。Mn is an element necessary for increasing the strength. However, if the Mn content exceeds 1.7% by weight, a bainite structure is generated and no yield point appears, so the upper limit is set to 1.7% by weight.
【００１３】Ｖは、析出強化元素であり、とくに少量の
添加でマトリックスの高強度化を図ることができるた
め、有効である。また、Ｖの添加は結晶粒の微細化にも
有効である。通常、高強度化に有効なＶ含有量は０．４
重量％以上である。しかし、ＶをＴｉとともに複合添加
した場合には、Ｖ含有量が０．７重量％を超えると、バ
ナジウム析出物およびチタン析出物の共存により、降伏
伸びが小さくなるので、Ｖの上限値を０．７重量％とす
る。V is a precipitation strengthening element, and is effective because it can increase the strength of the matrix by adding a small amount thereof. Further, the addition of V is also effective for making the crystal grains fine. Usually, the effective V content for strengthening is 0.4
% By weight or more. However, when V is added in combination with Ti, when the V content exceeds 0.7% by weight, the yield elongation becomes small due to the coexistence of vanadium precipitates and titanium precipitates. 0.7% by weight.
【００１４】Ｔｉは、本発明に用いる素材において必須
の元素である。Ｔｉは、高強度材料の降伏伸びを大きく
するのに有効であり、そのためにはＴｉ含有量を０．０
１重量％以上とする必要がある。Ｔｉ含有量が０．１０
重量％を超えると、降伏伸びの増大効果が飽和するの
で、上限値を０．１０重量％とする。[0014] Ti is an essential element in the material used in the present invention. Ti is effective in increasing the yield elongation of a high-strength material.
It must be at least 1% by weight. Ti content 0.10
If the amount exceeds 10% by weight, the effect of increasing the yield elongation is saturated, so the upper limit is set to 0.10% by weight.
【００１５】Ｎは、組織中ではＴｉＮまたはＶＮの形態
で存在し、組織の微細化に有効な元素である。Ｎ含有量
が０．００４重量％を下回ると、組織微細化の効果がみ
られない。一方、Ｎ含有量が０．０１重量％を超える
と、組織微細化の効果が飽和するので、上限値を０．０
１重量％とする。次に、圧延終了温度について説明す
る。N exists in the structure in the form of TiN or VN, and is an element effective for making the structure finer. If the N content is less than 0.004% by weight, the effect of refining the structure is not obtained. On the other hand, if the N content exceeds 0.01% by weight, the effect of refining the structure saturates.
1% by weight. Next, the rolling end temperature will be described.
【００１６】圧延終了温度を６５０〜９００℃の範囲と
する理由は、圧延終了温度が６５０℃を下回る条件で上
記組成の素材を熱間圧延すると、過冷組織を生じて降伏
伸びが小さくなること、および、圧延機の負担が大きく
なることによる。このため、圧延終了温度の下限値を６
５０℃とすることが望ましい。The reason for setting the rolling end temperature in the range of 650 to 900 ° C. is that when a material having the above composition is hot-rolled under the condition that the rolling end temperature is lower than 650 ° C., a supercooled structure is formed and the yield elongation is reduced. And that the load on the rolling mill increases. For this reason, the lower limit of the rolling end temperature is set to 6
It is desirable that the temperature be 50 ° C.
【００１７】一方、圧延終了温度の上限値を９００℃と
する理由は、圧延終了温度が９００℃を上回る条件で上
記組成の素材を熱間圧延すると、組織が粗大化して降伏
点が出現しにくくなり、所望の降伏伸びを得ることがで
きなくなるからである。これに対して、９００℃以下の
圧延終了温度となるように上記組成の素材を熱間圧延す
ると、組織が微細化し、降伏点が出現すると共に、降伏
伸びも大きくなる。この場合に、微細化組織はフェライ
トおよびパーライトの混合組織となる。従って、上記の
下限温度値との組合せにより圧延終了温度を６５０〜９
００℃の範囲に選ぶことが最も望ましい。On the other hand, the reason for setting the upper limit of the rolling end temperature to 900 ° C. is that when the material having the above composition is hot-rolled under the condition that the rolling end temperature is higher than 900 ° C., the structure becomes coarse and the yield point hardly appears. This is because the desired yield elongation cannot be obtained. On the other hand, when a material having the above composition is hot-rolled so as to have a rolling end temperature of 900 ° C. or lower, the structure becomes finer, a yield point appears, and the yield elongation increases. In this case, the microstructure becomes a mixed structure of ferrite and pearlite. Therefore, the above
The rolling end temperature is set to 650 to 9 in combination with the lower limit temperature value.
Most preferably, it is selected in the range of 00 ° C.
【００１８】[0018]
【実施例】以下、この発明の実施例について具体的に説
明する。Embodiments of the present invention will be specifically described below.
【００１９】表１は、各種組成の素材を示す成分表示で
ある。組成番号１乃至３は、本発明の実施例として挙げ
たものであり、本発明の素材の成分範囲に含まれる。組
成番号４乃至６は、比較例として挙げたものである。Table 1 is a component display showing materials of various compositions. Composition Nos. 1 to 3 are listed as examples of the present invention, and are included in the component range of the material of the present invention. Composition numbers 4 to 6 are listed as comparative examples.
【００２０】表２は、上記組成番号１乃至６の素材を種
々の圧延終了温度となるように所定の圧下率で圧延し、
それぞれの降伏強さ、引張強さ、並びに降伏伸びについ
て調べた試験結果を示す表である。Table 2 shows that the raw materials having composition numbers 1 to 6 were rolled at predetermined rolling reductions so as to have various rolling end temperatures.
It is a table | surface which shows the test result investigated about each yield strength, tensile strength, and yield elongation.
【００２１】図１に示すように、降伏伸びとは、降伏が
終了するまでの伸び量εP を上降伏点までの伸び量εY
で割った比率（εP ／εY ）をいう。なお、引張試験に
はＪＩＳ４号試験片を用い、標点間距離を５０mmとし
た。ここで、降伏強さは、実施例１，２，３及び比較例
１，２，８においては降伏点の表示強度を用いたが、比
較例３，４，５，６，７，９においては降伏点が明瞭に
認められないので０．２％耐力を採用した。表２から明
らかなように、実施例１，２，３は、いずれも降伏強さ
が７８０ＭＰａ以上となり、かつ、降伏伸びが４を超え
ている。As shown in FIG. 1, the yield elongation is defined as the elongation ε P up to the end of the yield, and the elongation ε Y up to the upper yield point.
Divided by (ε P / ε Y ). In the tensile test, a JIS No. 4 test piece was used, and the distance between gauge points was set to 50 mm. Here, as the yield strength, the display strength of the yield point was used in Examples 1, 2, and 3 and Comparative Examples 1, 2, and 8, but in Comparative Examples 3, 4, 5, 6, 7, and 9, Since the yield point was not clearly recognized, a 0.2% proof stress was adopted. As is clear from Table 2, in Examples 1, 2, and 3, the yield strength is 780 MPa or more, and the yield elongation exceeds 4.
【００２２】これに対して、圧延終了温度が６５０℃を
下回る条件の比較例１，３，５では、降伏伸びが得られ
ないか又は得られたとしても０．８程度の小さな降伏伸
びしか得られなかった。On the other hand, in Comparative Examples 1, 3, and 5 where the rolling end temperature is lower than 650 ° C., no yield elongation is obtained, or even if it is obtained, only a small yield elongation of about 0.8 is obtained. I couldn't.
【００２３】また、圧延終了温度が９００℃を超える条
件の比較例２，４，６では、降伏伸びが得られないか又
は得られたとしても２．０程度の小さな降伏伸びしか得
られなかった。なお、比較例３，４，５，６では、明瞭
な降伏点が出現せず、降伏伸びを測定することができな
かった。In Comparative Examples 2, 4, and 6 where the rolling end temperature exceeded 900 ° C., no yield elongation was obtained, or even if it was obtained, only a small yield elongation of about 2.0 was obtained. . In Comparative Examples 3, 4, 5, and 6, no clear yield point appeared, and the yield elongation could not be measured.
【００２４】さらに、比較例７，８，９の結果から明ら
かなように、圧延終了温度が６５０〜９００℃の範囲内
の条件であっても、所定の組成範囲から外れる組成（組
成番号４，５，６）のものでは、降伏伸びが小さくな
る。すなわち、比較例７及び９では降伏点が明瞭に出現
せず、また、比較例８では降伏点は現れるものの降伏伸
びは２．３程度と小さい。Further, as is apparent from the results of Comparative Examples 7, 8, and 9, even if the rolling end temperature is in the range of 650 to 900 ° C., the composition (composition number 4, In the case of (5, 6), the yield elongation becomes small. That is, in Comparative Examples 7 and 9, the yield point does not clearly appear, and in Comparative Example 8, the yield point appears but the yield elongation is as small as about 2.3.
【００２５】上記実施例によれば、素材の組成、とくに
チタン含有量およびバナジウム含有量を所定範囲とし、
６５０〜９００℃の範囲に圧延終了温度を選ぶことによ
り、組織の微細化を図り、降伏強さを低下させることな
く、降伏伸びを増大することができた。According to the above embodiment, the composition of the raw material, in particular, the content of titanium and the content of vanadium are set to predetermined ranges,
By selecting the rolling end temperature in the range of 650 to 900 ° C., it was possible to refine the structure and increase the yield elongation without lowering the yield strength.
【００２６】[0026]
【表１】 [Table 1]
【００２７】[0027]
【表２】 [Table 2]
【００２８】[0028]
【発明の効果】この発明によれば、鉄筋用棒鋼の降伏強
さを７８０ＭＰａ以上に向上させることができ、かつ、
降伏伸びを４以上にすることができる。従って、この発
明により製造した棒鋼は、超高層ビルの鉄筋コンクリ−
トに用いるのに最適である。According to the present invention, the yield strength of steel bars for reinforcing steel can be improved to 780 MPa or more, and
The yield elongation can be 4 or more. Accordingly, the steel bars manufactured according to the present invention are used for reinforcing concrete in skyscrapers.
Ideal for use in
【図１】降伏伸びを説明するための応力−歪線図。FIG. 1 is a stress-strain diagram for explaining yield elongation.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平４−56727（ＪＰ，Ａ) 特開 平４−193908（ＪＰ，Ａ) 特開 平５−9577（ＪＰ，Ａ) 永井義規”高強度鉄筋ＳＤ50の機械的 性質”，材料とプロセス，Ｖｏｌ．３, （1990），1398 (58)調査した分野(Int.Cl.7，ＤＢ名) C21D 8/08 ────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-56727 (JP, A) JP-A-4-193908 (JP, A) JP-A-5-9577 (JP, A) Nagai Yoshinori "High strength" Mechanical Properties of Reinforcing Bar SD50 ", Materials and Processes, Vol. 3, (1990), 1398 (58) Fields investigated (Int. Cl. 7 , DB name) C21D 8/08
Claims (1)
１．５質量％以下，Ｍｎを１．７質量％以下，Ｖを０．
４〜０．７質量％，Ｔｉを０．０１〜０．１０質量％，
Ｎを０．００４〜０．０１質量％それぞれ含有し、残部
がＦｅ及び不可避的不純物からなる素材を、圧延終了温
度が６５０〜９００℃となるように圧延することを特徴
とする高強度鉄筋用鋼の製造方法。 C. 0.35 to 0.50 mass% of C and Si
1.5 mass% or less, Mn 1.7 mass% or less, V
4 to 0.7% by mass, 0.01 to 0.10% by mass of Ti,
N in an amount of 0.004 to 0.01% by mass, and the balance
Is a material consisting of Fe and unavoidable impurities,
Rolled to a degree of 650-900 ° C
Method for producing high-strength steel for reinforcing steel.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3223237A JP3060635B2 (en) | 1990-09-04 | 1991-09-04 | Manufacturing method of steel for high strength rebar |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2-232475 | 1990-09-04 | ||
| JP23247590 | 1990-09-04 | ||
| JP3223237A JP3060635B2 (en) | 1990-09-04 | 1991-09-04 | Manufacturing method of steel for high strength rebar |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0551636A JPH0551636A (en) | 1993-03-02 |
| JP3060635B2 true JP3060635B2 (en) | 2000-07-10 |
Family
ID=26525345
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3223237A Expired - Fee Related JP3060635B2 (en) | 1990-09-04 | 1991-09-04 | Manufacturing method of steel for high strength rebar |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3060635B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112080682A (en) * | 2020-09-23 | 2020-12-15 | 宁夏建龙龙祥钢铁有限公司 | Method for increasing vanadium content of molten deformed steel bar by using vanadium-containing titanium-containing pig iron block |
| CN115261720B (en) * | 2022-06-29 | 2023-05-05 | 张家港荣盛特钢有限公司 | Fireproof steel bar mechanical connecting sleeve, wire rod and production method of wire rod |
-
1991
- 1991-09-04 JP JP3223237A patent/JP3060635B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| 永井義規"高強度鉄筋ＳＤ５０の機械的性質"，材料とプロセス，Ｖｏｌ．３，（１９９０），１３９８ |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0551636A (en) | 1993-03-02 |
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