JPH0525543A - Production of reinforcing steel having high strength and high yield elongation - Google Patents
Production of reinforcing steel having high strength and high yield elongationInfo
- Publication number
- JPH0525543A JPH0525543A JP20350491A JP20350491A JPH0525543A JP H0525543 A JPH0525543 A JP H0525543A JP 20350491 A JP20350491 A JP 20350491A JP 20350491 A JP20350491 A JP 20350491A JP H0525543 A JPH0525543 A JP H0525543A
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- Prior art keywords
- yield
- strength
- yield elongation
- rolling
- steel
- Prior art date
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、高強度、特に下降伏
点が690MPa以上の高強度を有し、しかも、降伏伸びの大
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 a steel for reinforcing bars which has a high strength, particularly a high yield strength of 690 MPa or more and a large yield elongation.
【０００２】[0002]
【従来の技術】鉄筋コンクリート用棒鋼は、JIS G3112
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。このような棒鋼は一般に
C−Mn鋼を熱間圧延して製造される。[Prior Art] Steel bars for reinforced concrete are JIS G3112
Even if the strength is maximum, the yield point will
490 to 630 MPa (SD490). Such steel bars are generally
It is manufactured by hot rolling C-Mn steel.
【０００３】一方、鉄筋コンクリー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、鉄筋を更に高
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、降伏伸び（εｐ／εｙ・図１参照）が逆に
低下するという不都合が生じる。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
で降伏伸び値が４以上であることが好ましいとされてお
り、その場合高強度化に伴う降伏伸びの低下は大きな問
題となる。On the other hand, a building made of reinforced concrete tends to be made higher in height, and there is a strong demand for further strengthening of the reinforcing bar. However, generally, when the strength of a steel bar is increased, the yield elongation (εp / εy, see FIG. 1) is disadvantageously decreased. By the way, NewRC of Ministry of Construction
According to the guideline of the comprehensive project, it is preferable that the yield point is 690 MPa or more and the yield elongation value is 4 or more. In that case, the decrease of the yield elongation due to the strengthening becomes a big problem.
【０００４】これに対し、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N
b、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Nb、V、Caを含有することによって高強度な鉄筋用
鋼が得られることについての記載がある。On the other hand, Japanese Patent Publication No. 63-64494 discloses that Nb-containing steel or N-containing steel should be used in order to increase the strength of steel bars.
A manufacturing technique is described in which b- and V-containing steel is used as a raw material and controlled rolling is performed under predetermined rolling conditions in order to suppress a decrease in yield elongation. Further, Japanese Patent Publication No. 64-11705 describes that a steel for reinforcing bars having high strength can be obtained by containing Nb, V and Ca.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、これら
の従来の製造方法では、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、降伏点が低下してしまい、従って690M
Pa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かった。However, in these conventional manufacturing methods, a relatively low strength steel bar having a yield point of 490 to 590 MPa is targeted, and a high strength steel bar having a yield point exceeding these is targeted. Not meant to be. In other words, even in these technologies, if an attempt is made to increase the yield elongation of steel bar, the yield point will be lowered, and therefore 690M
It was not possible to manufacture a high-strength and high-yield elongation steel bar having a yield point of Pa or higher.
【０００６】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。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 bars having high strength and large yield elongation.
【０００７】[0007]
【課題を解決するための手段】本発明者等は、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
延終了温度の低減化を図ることにより降伏点が出現する
こと、それに加えて、ニオブを有効利用することにより
降伏伸びが増大することを見出した。Means for Solving the Problems The inventors of the present invention have earnestly studied in order to obtain steel for high-strength reinforcing bars. It has been found that the yield point appears by increasing the yield, and that the yield elongation increases by effectively using niobium.
【０００８】この発明に係る高強度鉄筋用鋼の製造方法
は、Cを0.2〜0.4wt％、Siを0.5wt％以下、Mnを1.7wt％
以下、Crを1.0wt％以下、（Mn＋Cr）を1.7wt％以下、V
を0.15〜0.5wt％、Nbを0.15〜0.4wt％、Nを0.004〜0.01
wt％、更に必要に応じて、ZrまたはTiの１種以上を0.01
〜0.10wt％含有し、残部がFe及び不可避的不純物からな
る鋼を、圧延終了温度が900℃以下となるように圧延す
ることを特徴とする。The method for producing a steel for high-strength reinforcing steel according to the present invention comprises 0.2 to 0.4 wt% C, 0.5 wt% or less Si, and 1.7 wt% Mn.
Below, Cr is 1.0wt% or less, (Mn + Cr) is 1.7wt% or less, V
0.15 to 0.5 wt%, Nb 0.15 to 0.4 wt%, N 0.004 to 0.01
wt%, and if necessary, 0.01 or more of Zr or Ti
It is characterized in that steel containing 0.1 to 0.10 wt% and the balance of Fe and unavoidable impurities is rolled so that the rolling end temperature is 900 ° C. or lower.
【０００９】鋼の組成をこのような成分範囲とした理由
について、各成分元素毎に以下に説明する。The reason why the composition of steel is set in such a composition range will be described below for each composition 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0.2wt％以上とする必要
がある。しかし、C含有量が0.4wt％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0.4wt％とす
る。C is an element necessary for increasing the strength, and its content must be 0.2 wt% or more to obtain a desired strength level. However, if the C content exceeds 0.4 wt%, the yield point becomes difficult to appear, or even if the yield point appears, the yield elongation becomes small, so the upper limit is made 0.4 wt%.
【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0.5wt％を超えると靱性が低下するので、上
限値を0.5wt％とする。Si is an element necessary for deoxidation, and is effective in forming a solid solution in the matrix to increase the strength. But,
If the Si content exceeds 0.5 wt%, the toughness decreases, so the upper limit is made 0.5 wt%.
【００１２】Mnは高強度化に必要な元素である。しか
し、Mn含有量が1.7wt％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1.7wt％
とする。Mn is an element necessary for increasing the strength. However, if the Mn content exceeds 1.7 wt%, a bainite structure is formed and the yield point does not appear, so the upper limit is 1.7 wt%.
And
【００１３】Crは高強度化に必要な元素である。しか
し、Cr含有量が1.0wt％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1.0wt％
とする。但し、CrおよびMnの含有量の合計が1.7wt％を
超えた場合においても、ベイナイト組織を生じるので、
（Mn＋Cr）合計含有量の上限値は1.7wt％とする。Cr is an element necessary for increasing the strength. However, if the Cr content exceeds 1.0 wt%, a bainite structure is formed and the yield point does not appear, so the upper limit is 1.0 wt%.
And However, even when the total content of Cr and Mn exceeds 1.7 wt%, a bainite structure is formed,
The upper limit of the total content of (Mn + Cr) is 1.7 wt%.
【００１４】Vは、析出強化元素であり、特に少量で高
強度化を図ることができるため有効である。高強度化に
有効なV含有量は0.15wt％以上である。しかし、V含有量
が0.5wt％を超えると降伏伸びが小さくなるので、上限
値を0.5wt％とする。V is a precipitation-strengthening element, and is particularly effective because a small amount can enhance the strength. The V content effective for strengthening is 0.15 wt% or more. However, if the V content exceeds 0.5 wt%, the yield elongation decreases, so the upper limit is made 0.5 wt%.
【００１５】Nbは本発明に用いる素材において必須の元
素である。Nb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Nb含有量を0.15wt％以上とす
る必要がある。一方Nb含有量が0.4wt％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0.4wt％と
する。Nb is an essential element in the material used in the present invention. Nb is effective in increasing the yield elongation of high-strength materials, and for that purpose the Nb content must be 0.15 wt% or more. On the other hand, if the Nb content exceeds 0.4 wt%, the effect of increasing yield elongation saturates, so the upper limit is made 0.4 wt%.
【００１６】Nは組織中でNb（C，N）、VNの形態で存在
することで、組織の微細化に有効な元素となる。しかし
N含有量が0.004wt％を下回ると、組織微細化の効果が見
られない。一方、N含有量が0.01wt％を超えると、組織
微細化の効果が飽和するので、上限値を0.01wt％とす
る。Since N exists in the form of Nb (C, N) and VN in the structure, it becomes an effective element for making the structure fine. However
If the N content is less than 0.004 wt%, the effect of refining the structure is not observed. On the other hand, if the N content exceeds 0.01 wt%, the effect of microstructure refinement is saturated, so the upper limit is made 0.01 wt%.
【００１７】ZrまたはTiはNbの効果を促進する元素であ
る。しかし、その含有量が0.01wt％未満では、Nb単独添
加のものと同等の降伏伸びしか示さない。従って、含有
量を0.01wt％以上とする。また、0.10wt％を超えても効
果が飽和するので、上限値を0.10wt％とする。Zr or Ti is an element that promotes the effect of Nb. However, if its content is less than 0.01 wt%, it shows only a yield elongation equivalent to that of Nb alone added. Therefore, the content is set to 0.01 wt% or more. Moreover, the effect is saturated even if it exceeds 0.10 wt%, so the upper limit is made 0.10 wt%.
【００１８】以上は圧延素材の成分組成の限定理由につ
いて説明した。The reasons for limiting the composition of the rolled material have been described above.
【００１９】次に圧延終了温度を900℃以下にした理由
は、上記組成の素材を熱間圧延する際に圧延終了温度を
900℃以下にすると、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からである。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。逆に圧延終了温度が900℃を超える場合は、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い。Next, the reason why the rolling finish temperature is set to 900 ° C. or lower is that the rolling finish temperature is set when hot rolling the material having the above composition.
This is because if the temperature is 900 ° C. or lower, the structure becomes finer, the yield point appears, and the yield elongation increases. In this case, the refined structure is a mixed structure of ferrite and pearlite. On the other hand, when the rolling end temperature exceeds 900 ° C., the structure becomes coarse and the yield point hardly appears, and the desired yield elongation cannot be obtained.
【００２０】尚、下限温度については特に規定はない
が、650℃より低温での圧延は過冷組織を生じ降伏伸び
が小さくなることと、圧延機の負担が大きくなることか
ら、圧延終了温度は650℃以上とするのが好ましい。The lower limit temperature is not specified, but rolling at a temperature lower than 650 ° C. results in a supercooled structure, which causes a small yield elongation and a heavy load on the rolling mill. It is preferably 650 ° C or higher.
【００２１】[0021]
【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.
【００２２】下記表１は各種組成の素材を示す成分表で
ある。組成番号１〜６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。又組成
番号７〜１１は比較例として挙げたものである。Table 1 below is a component table showing materials of various compositions. Composition numbers 1 to 6 are given as examples of the present invention and are included in the ingredient range of the material of the present invention. Composition numbers 7 to 11 are given as comparative examples.
【００２３】[0023]
【表１】 [Table 1]
【００２４】又次表２は上記組成番号１〜１１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している。ここで降伏伸びと
は、前述の図１に示される様に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）を言う。尚、引張試験にはJIS 4号試験片を用
い、標点距離を５０mmとした。また、比較例３、４、８
及び１１では降伏強さの代わりに0.2％耐力を用いて表
示している。Further, in Table 2 below, the materials having the above composition numbers 1 to 11 were rolled at a predetermined rolling reduction ratio so as to have various rolling finish temperatures, and the respective yield strengths, tensile strengths and yield elongations were examined. The test results are shown. Here, the yield elongation is the ratio of the amount of elongation εp until the end of yielding divided by the amount of elongation εy to the upper yield point (εp, as shown in FIG. 1).
/ Εy). A JIS No. 4 test piece was used for the tensile test, and the gauge length was 50 mm. In addition, Comparative Examples 3, 4, 8
In Nos. 11 and 11, 0.2% proof stress is used instead of yield strength.
【００２５】[0025]
【表２】 [Table 2]
【００２６】以上の結果を比較検討するに、実施例１〜
６はいずれも降伏強さが690MPa以上となり、かつ降伏伸
びが４を超えていることがわかる。To compare and examine the above results, Examples 1 to 1
It can be seen that all of 6 have yield strengths of 690 MPa or more and yield elongations of more than 4.
【００２７】これに対して圧延終了温度が900℃を超え
る条件の比較例１〜６では、降伏伸びが非常に小さくな
り、1.7以下の降伏伸びしか得られない。なお、比較例
３、４に至っては、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。On the other hand, in Comparative Examples 1 to 6 where the rolling end temperature exceeds 900 ° C., the yield elongation is very small and only a yield elongation of 1.7 or less is obtained. In Comparative Examples 3 and 4, a clear yield point did not appear, and the yield elongation could not be measured.
【００２８】更に、圧延終了温度が900℃を下回るもの
であっても、組成が本発明の範囲を外れるもの（比較例
７〜１１）では、降伏伸びが小さくなる。即ち、比較例
８、１１では明瞭な降伏点が出現しなかったし、また、
比較例７、９、１０のように降伏点が出現するものであ
っても、降伏伸びは３未満と小さい。Further, even if the rolling end temperature is lower than 900 ° C., if the composition is out of the range of the present invention (Comparative Examples 7 to 11), the yield elongation is small. That is, no clear yield point appeared in Comparative Examples 8 and 11, and
Even if the yield point appears as in Comparative Examples 7, 9, and 10, the yield elongation is small, less than 3.
【００２９】上記実施例によれば、素材の組成とくにV
含有量、Nb含有量を所定の範囲とし、必要に応じてZr、
Tiも所定の範囲で含んで、圧延終了温度を所定の範囲に
コントロールすることによって、組織の微細化を図るこ
とができ、従って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 examples, the composition of the material, especially V
Content, Nb content within a predetermined range, if necessary Zr,
By including Ti in a predetermined range and controlling the rolling end temperature within a predetermined range, it is possible to achieve a finer structure, and thus to increase the yield elongation without lowering the yield strength. It was
【００３０】[0030]
【発明の効果】この発明によれば、降伏伸びが４以上と
大きく、且つ降伏強さにして690MPa以上の高強度の鉄筋
用鋼が得られることになり、この鋼で製造した棒鋼は超
高層ビルの鉄筋コンクリートに用いるのに適することに
なる。EFFECTS OF THE INVENTION According to the present invention, a steel for reinforcing bars having a high yield elongation of 4 or more and a yield strength of 690 MPa or more can be obtained. It will be suitable for use in building reinforced concrete.
【図１】降伏伸びについての説明を行なうグラフであ
る。FIG. 1 is a graph for explaining yield elongation.
Claims (2)
n：1.7wt％以下、Cr：1.0wt％以下、（Mn＋Cr）：1.7wt
％以下、V：0.15〜0.5wt％、Nb：0.15〜0.4wt％、N：0.
004〜0.01wt％を含有し、残部がFe及び不可避的不純物
から成る鋼を圧延終了温度900℃以下で圧延することを
特徴とする高強度且つ降伏伸びの大きい鉄筋用鋼の製造
方法。1. C: 0.2 to 0.4 wt%, Si: 0.5 wt% or less, M
n: 1.7 wt% or less, Cr: 1.0 wt% or less, (Mn + Cr): 1.7 wt
%, V: 0.15 to 0.5 wt%, Nb: 0.15 to 0.4 wt%, N: 0.
A method for producing a steel for reinforcing bars having high strength and large yield elongation, which comprises rolling a steel containing 004 to 0.01 wt% and the balance being Fe and unavoidable impurities at a rolling end temperature of 900 ° C or lower.
n：1.7wt％以下、Cr：1.0wt％以下、（Mn＋Cr）：1.7wt
％以下、V：0.15〜0.5wt％、Nb：0.15〜0.4wt％、N：0.
004〜0.01wt％を含有し、更にZrまたはTiの１種以上を
0.01〜0.10wt％含んで、残部がFe及び不可避的不純物か
ら成る鋼を圧延終了温度900℃以下で圧延することを特
徴とする高強度且つ降伏伸びの大きい鉄筋用鋼の製造方
法。2. C: 0.2 to 0.4 wt%, Si: 0.5 wt% or less, M
n: 1.7 wt% or less, Cr: 1.0 wt% or less, (Mn + Cr): 1.7 wt
%, V: 0.15 to 0.5 wt%, Nb: 0.15 to 0.4 wt%, N: 0.
004-0.01 wt%, and further contains one or more Zr or Ti
A method for producing a steel for reinforcing bars having high strength and large yield elongation, which comprises rolling steel containing 0.01 to 0.10 wt% and the balance being Fe and unavoidable impurities at a rolling end temperature of 900 ° C or lower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20350491A JPH0525543A (en) | 1991-07-19 | 1991-07-19 | Production of reinforcing steel having high strength and high yield elongation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20350491A JPH0525543A (en) | 1991-07-19 | 1991-07-19 | Production of reinforcing steel having high strength and high yield elongation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0525543A true JPH0525543A (en) | 1993-02-02 |
Family
ID=16475255
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20350491A Withdrawn JPH0525543A (en) | 1991-07-19 | 1991-07-19 | Production of reinforcing steel having high strength and high yield elongation |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0525543A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09324215A (en) * | 1996-06-07 | 1997-12-16 | Kobe Steel Ltd | Manufacture of high strength reinforcing bar excellent in yield elongation and bendability |
| CN103255349A (en) * | 2013-04-26 | 2013-08-21 | 江苏省沙钢钢铁研究院有限公司 | Small-size 600MPa-level aseimatic twisted steel and manufacturing method thereof |
| CN103255358A (en) * | 2012-12-24 | 2013-08-21 | 武钢集团昆明钢铁股份有限公司 | High strength anti-seismic reinforcing steel bar and production method thereof |
| CN104018075A (en) * | 2014-06-25 | 2014-09-03 | 武汉钢铁(集团)公司 | Hot rolled ribbed steel bar with yield-to-tensile ratio of less than or equal to 0.8 and Rel of more than or equal to 600MPa, and production method |
| CN110684931A (en) * | 2019-10-24 | 2020-01-14 | 柳州钢铁股份有限公司 | Control method for non-yield phenomenon of niobium microalloyed HRB400E hot-rolled ribbed steel bar |
| CN110819907A (en) * | 2019-10-24 | 2020-02-21 | 柳州钢铁股份有限公司 | Niobium microalloyed HRB400E hot-rolled ribbed steel bar |
-
1991
- 1991-07-19 JP JP20350491A patent/JPH0525543A/en not_active Withdrawn
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09324215A (en) * | 1996-06-07 | 1997-12-16 | Kobe Steel Ltd | Manufacture of high strength reinforcing bar excellent in yield elongation and bendability |
| CN103255358A (en) * | 2012-12-24 | 2013-08-21 | 武钢集团昆明钢铁股份有限公司 | High strength anti-seismic reinforcing steel bar and production method thereof |
| CN103255349A (en) * | 2013-04-26 | 2013-08-21 | 江苏省沙钢钢铁研究院有限公司 | Small-size 600MPa-level aseimatic twisted steel and manufacturing method thereof |
| CN103255349B (en) * | 2013-04-26 | 2015-08-26 | 江苏省沙钢钢铁研究院有限公司 | A kind of small dimension 600MPa level antidetonation Twisted Steel and manufacture method thereof |
| CN104018075A (en) * | 2014-06-25 | 2014-09-03 | 武汉钢铁(集团)公司 | Hot rolled ribbed steel bar with yield-to-tensile ratio of less than or equal to 0.8 and Rel of more than or equal to 600MPa, and production method |
| CN104018075B (en) * | 2014-06-25 | 2016-05-04 | 武汉钢铁(集团)公司 | Rel >=600MPa hot rolled ribbed bars and the production method of yield tensile ratio≤0.8 |
| CN110684931A (en) * | 2019-10-24 | 2020-01-14 | 柳州钢铁股份有限公司 | Control method for non-yield phenomenon of niobium microalloyed HRB400E hot-rolled ribbed steel bar |
| CN110819907A (en) * | 2019-10-24 | 2020-02-21 | 柳州钢铁股份有限公司 | Niobium microalloyed HRB400E hot-rolled ribbed steel bar |
| CN110684931B (en) * | 2019-10-24 | 2020-11-27 | 柳州钢铁股份有限公司 | Control method for non-yield phenomenon of niobium microalloyed HRB400E hot-rolled ribbed steel bar |
| CN110819907B (en) * | 2019-10-24 | 2020-11-27 | 柳州钢铁股份有限公司 | Niobium microalloyed HRB400E hot-rolled ribbed steel bar |
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