JPH073396A - Steel for pc excellent in uniform elongation and production thereof - Google Patents
Steel for pc excellent in uniform elongation and production thereofInfo
- Publication number
- JPH073396A JPH073396A JP17274393A JP17274393A JPH073396A JP H073396 A JPH073396 A JP H073396A JP 17274393 A JP17274393 A JP 17274393A JP 17274393 A JP17274393 A JP 17274393A JP H073396 A JPH073396 A JP H073396A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- uniform elongation
- steel material
- tempering
- tempering temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Reinforcement Elements For Buildings (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、プレストレストコンク
リート（ＰＣ）くいの補強筋等に使用されるＰＣ用鋼
材、特に一様伸び特性が改善された鋼材に関するもので
ある。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel material for PC used for reinforcing bars of prestressed concrete (PC) piles, and more particularly to a steel material having improved uniform elongation characteristics.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】ＰＣ鋼
材の高強度化の具体的手段として、焼入れ・焼戻しによ
る方法があり、その焼戻し温度は一般に３００〜５００
℃である（例えば特公昭54-38571号公報や特公昭62-493
34号公報参照）。これらの技術で製造されたＰＣ鋼材
は、一般にＰＣパイルやＰＣポールなどの補強筋として
使用され、所定の緊張力を与えられた後、長時間緊張状
態で保持されるもので、代表的な鋼材としてはJIS G 31
09に規定されるＤ種ＰＣ鋼棒がある。2. Description of the Related Art As a concrete means for increasing the strength of PC steel materials, there is a method of quenching and tempering, and the tempering temperature is generally 300 to 500.
° C (for example, Japanese Patent Publication No. 54-38571 and Japanese Patent Publication No. 62-493).
(See Japanese Patent Publication No. 34). PC steel materials manufactured by these techniques are generally used as reinforcing bars for PC piles, PC poles, etc., and are held in a tension state for a long time after being given a predetermined tension force. As JIS G 31
There are Class D PC steel rods specified in 09.
【０００３】近年、ＰＣ構造物の耐震設計の見直しが積
極的に検討され、例えば、コンクリート工学年次論文報
告集9-2、1987の［2080］、［2082］論文において、ＰＣ
くいそのものの性能改善に対して重要な提言がなされて
いる。特に、論文［2082］では、一様伸び５％以上の高
一様伸びＰＣ鋼棒と横拘束コンクリートを併用すること
により、ＰＣくいの曲げ靱性が改善されることを指摘し
ている。In recent years, the review of seismic design of PC structures has been positively studied. For example, in the concrete engineering annual report 9-2, 1987 [2080] and [2082], PC
Important suggestions have been made for improving the performance of the pile itself. In particular, the paper [2082] points out that the bending toughness of PC piles is improved by using a combination of a high uniform elongation PC steel bar having a uniform elongation of 5% or more and laterally constrained concrete.
【０００４】ここで、一様伸びとは、鋼材の引張試験に
よる応力−歪曲線において、荷重の増加にともなって、
試験片が均一に伸び、荷重が最大値に達した後、その一
部にくびれ（絞り）を生じて破断に至る過程のうち最大
荷重までの均一な伸びをいう。Here, the uniform elongation means that as the load increases in the stress-strain curve in the tensile test of steel,
After the test piece is uniformly stretched and the load reaches the maximum value, a uniform stretch is obtained up to the maximum load in the process of causing constriction (drawing) in a part of the test piece and breaking.
【０００５】しかし、現在製造・市販中のＰＣくい用鋼
材、例えばJIS G 3109のＤ種鋼棒の一様伸びは４％程度
であり、これを使用したＰＣくいに横拘束を行った場合
には、ＰＣ鋼棒の破断が早期に起こり、横拘束コンクリ
ートの能力が十分に発揮される前にＰＣくいが破断する
という問題があった。この点は、前述の論文で明確に指
摘されており、鋼材の一様伸びを改善することが強く希
求されていた。However, the uniform elongation of the steel material for PC piles currently manufactured and marketed, for example, JIS G 3109 class D steel bar, is about 4%, and when PC piles using this are laterally constrained. Had a problem that the PC steel rod broke early and the PC pile broke before the capacity of the laterally constrained concrete was fully exerted. This point was clearly pointed out in the above-mentioned paper, and it was strongly desired to improve the uniform elongation of steel.
【０００６】従って、本発明は上記の課題を解決するた
めになされたものであって、その目的は、一様伸びが改
善されたＰＣ用鋼材及びその製造方法を提供することに
ある。Therefore, the present invention has been made to solve the above problems, and an object thereof is to provide a steel material for PC having improved uniform elongation and a method for producing the same.
【０００７】[0007]
【課題を解決するための手段】上記の目的を達成するた
めに、本発明ＰＣ鋼材は、Ｃ：０．４５〜０．６０、Ｓ
ｉ：１．００〜１．５０、Ｍｎ：０．５０〜０．９０、
Ｃｒ：０．５０〜０．８０（全て重量％）を含有し、引
張強さが１４２０Ｎ／ｍｍ2 以上であって、一様伸びが
５％以上であることを特徴とするものである。In order to achieve the above object, the PC steel material of the present invention is C: 0.45 to 0.60, S
i: 1.00 to 1.50, Mn: 0.50 to 0.90,
Cr: 0.50 to 0.80 (all weight%) is contained, the tensile strength is 1420 N / mm 2 or more, and the uniform elongation is 5% or more.
【０００８】又、このＰＣ鋼材を製造する方法は、ＰＣ
鋼材の一様伸びが製造工程中の焼戻し条件と密接な関係
があるとの知見に基づくもので、Ｃ：０．４５〜０．６
０、Ｓｉ：１．００〜１．５０、Ｍｎ：０．５０〜０．
９０、Ｃｒ：０．５０〜０．８０（全て重量％）を含有
する鋼材を、５００℃以上６５０℃以下の焼戻し温度ま
で加熱後、急冷することを特徴とするものである。Further, the method for producing this PC steel material is
Based on the finding that the uniform elongation of the steel material is closely related to the tempering conditions during the manufacturing process, C: 0.45 to 0.6
0, Si: 1.00 to 1.50, Mn: 0.50 to 0.
A steel material containing 90, Cr: 0.50 to 0.80 (all weight%) is heated to a tempering temperature of 500 ° C. or more and 650 ° C. or less and then rapidly cooled.
【０００９】[0009]
【作用】一様伸びが５％以上であればＰＣ構造物の曲げ
靱性向上に有効であることは既に述べたが、上記のよう
な組成の鋼材において、焼戻し温度を５００℃以上の高
温側に移行させることにより一様伸びを著しく改善する
ことができる。即ち、５００℃以上６５０℃以下の焼戻
し温度まで加熱した後、急冷することにより、一様伸び
を５％以上とすることができるのである。It has already been described that if the uniform elongation is 5% or more, it is effective for improving the bending toughness of the PC structure. However, in the steel material having the above composition, the tempering temperature should be set to a high temperature side of 500 ° C or more. The uniform elongation can be remarkably improved by shifting. That is, the uniform elongation can be made 5% or more by heating to a tempering temperature of 500 ° C. or more and 650 ° C. or less and then quenching.
【００１０】この焼戻し温度の条件は、一様伸びを５％
以上を確保すると共に、ＰＣ鋼材として必要な機械的特
性を得るために定められたものである。特にＰＣパイル
やポールで慣用的に使用されているJIS G 3109のＤ種に
相当する機械的特性を基準とした。尚、引張強さの下限
については、鋼材の実用性、即ちＰＣパイル等の現設計
に影響を及ぼさないことを考慮し、Ｄ種規格値を基準と
した。焼戻し温度が５００℃未満では一様伸びの改善効
果が極めて少なく、５％以上の一様伸びを得ることがで
きない。逆に、６５０℃を越えると、一様伸びは改善さ
れるが、引張強さの低下が大きく、慣用ＰＣ鋼棒Ｄ種の
引張強さを下回ってしまい、ＰＣパイルに配筋する本数
を変更する等、ＰＣ鋼材としての実用性が大きく低下す
る。The tempering temperature is such that the uniform elongation is 5%.
It is defined in order to secure the above and to obtain the mechanical properties required as a PC steel material. In particular, the mechanical characteristics corresponding to JIS G 3109 Class D, which is commonly used for PC piles and poles, were used as the standard. The lower limit of the tensile strength is based on the D-class standard value in consideration of the practicality of the steel material, that is, the fact that it does not affect the current design of the PC pile or the like. If the tempering temperature is less than 500 ° C, the effect of improving uniform elongation is extremely small, and uniform elongation of 5% or more cannot be obtained. On the other hand, if the temperature exceeds 650 ° C, the uniform elongation is improved, but the tensile strength is greatly reduced and falls below the tensile strength of the conventional PC steel rod class D, and the number of reinforcements in the PC pile is changed. As a result, the practicality as a PC steel material is significantly reduced.
【００１１】尚、本発明において鋼材の組成を限定した
理由は以下の通りである。 Ｃ：現在慣用のＰＣ鋼棒のＣ含有量は０．２０〜０．
４０％程度であり、この範囲では焼戻し温度の高温化に
伴う引張強さの低下が大きく、高温焼戻しの大きな制約
となる。そのため、Ｃ含有量を増量し、０．４５〜０．
６０％とした。下限はＤ種相当の引張強さを得られる必
要最小限の量とし、上限は熱処理により製作される製品
の特性がＰＣ鋼棒の基本特性を満足できる値とした。 Ｓｉ：焼戻し軟化抵抗を高め、焼戻し温度を高温に移
行させるのに有効な元素であると共に、ＰＣ鋼材として
重要な高温リラクセーション特性，遅れ破壊特性を改善
するのにも有効である。しかし、１．５％を越えると靱
性が低下する。 Ｍｎ：脱酸剤として必要な元素であると共に、焼入れ
時に強度を高めるものである。そのため、現在の慣用Ｐ
Ｃ鋼棒に既に相当量含有されており、含有量の範囲はほ
ぼ同量とした。 Ｃｒ：焼戻し軟化抵抗を高め、焼戻し温度を高温に移
行させるのに最も有効な元素で、その効果を得るために
０．５０％程度は必要であり、０．８０％を越えると増
量に伴う効果が小さく、無駄な原料コストの増加につな
がるため必要最小限に抑えた。The reason why the composition of the steel material is limited in the present invention is as follows. C: The C content of the currently used PC steel bar is 0.20 to 0.
It is about 40%, and in this range, the tensile strength is greatly reduced with the increase in tempering temperature, which is a major limitation of high temperature tempering. Therefore, the C content is increased to 0.45 to 0.
It was set to 60%. The lower limit was set to the minimum amount necessary to obtain tensile strength equivalent to D type, and the upper limit was set to a value at which the properties of the product manufactured by heat treatment could satisfy the basic properties of PC steel bar. Si: It is an element effective in increasing the temper softening resistance and shifting the tempering temperature to a high temperature, and is also effective in improving the high temperature relaxation characteristics and delayed fracture characteristics important as PC steel materials. However, if it exceeds 1.5%, the toughness decreases. Mn: It is an element necessary as a deoxidizing agent and also enhances the strength during quenching. Therefore, the current conventional P
The C steel rod already contains a considerable amount, and the range of the content was set to be approximately the same. Cr: An element that is most effective in increasing the temper softening resistance and shifting the tempering temperature to a high temperature. About 0.50% is necessary to obtain the effect, and if it exceeds 0.80%, the effect of increasing the amount It is small and leads to unnecessary increase in raw material cost, so it was kept to the minimum necessary.
【００１２】[0012]
【試験例】以下に述べるいくつかの試験を通して本発明
を具体的に説明する。ＰＣ鋼材を作製し、得られた鋼材
の機械的特性を試験した。製造方法は、後に述べる各試
験例において共通で、所定の化学成分の鋼素材に焼入れ
を行い、所定の焼戻し温度迄急速に加熱した後急冷し
た。その際、焼戻し加熱手段は高周波誘導加熱方式を採
用し、冷却手段はノズルジェット水冷方式を用いた。
尚、鋼材形状はJIS G 3109に規定される異形棒に相当す
るものとした。[Test Example] The present invention will be specifically described through several tests described below. A PC steel material was prepared and the mechanical properties of the obtained steel material were tested. The manufacturing method is common to each of the test examples described later. A steel material having a predetermined chemical composition was quenched, rapidly heated to a predetermined tempering temperature, and then rapidly cooled. At that time, a high frequency induction heating method was adopted as the tempering heating means, and a nozzle jet water cooling method was used as the cooling means.
The shape of the steel material is equivalent to the deformed bar specified in JIS G 3109.
【００１３】（試験例１）先ず、化学成分がＣ：０．３
０、Ｓｉ：０．２９、Ｍｎ：０．７９、Ｃｒ：０．０４
（全て重量％）で、８ｍｍφの鋼素材を７．２４ｍｍφ
に異形加工したもの（現在慣用のＰＣ鋼棒）を前記製造
方法で作製した。このとき、焼戻し温度を３００〜６０
０℃に変化させ、各温度条件で得られた鋼材の機械的性
質、特に一様伸びの挙動を詳細に調べた。Test Example 1 First, the chemical composition was C: 0.3.
0, Si: 0.29, Mn: 0.79, Cr: 0.04
(All in% by weight), steel material of 8mmφ is 7.24mmφ
A deformed steel sheet (currently commonly used PC steel bar) was manufactured by the above-mentioned manufacturing method. At this time, the tempering temperature is 300 to 60
The mechanical properties, especially the behavior of uniform elongation, of the steel material obtained under each temperature condition after changing to 0 ° C. were investigated in detail.
【００１４】試験方法は、各鋼材についてJIS G 3109に
規定される引張試験を行い、引張強さ、降伏点及び伸び
を測定した。ここで、一様伸びは標点間距離２００ｍｍ
の特殊伸びゲージを用い、０．０２ｍｍ（０．１％歪
量）ごとに荷重と伸びを読み取り、鋼材にくびれ（絞
り）が発生するまでの荷重−伸び曲線を作成して読み取
った。尚、くびれ発生の有無は、荷重の負荷を一時静止
させ、マイクロメータを用いて鋼材直径の変化を調べて
確認した。その結果を図１に示す。同図に示すように、
焼戻し温度が５００℃前後からそれまであまり変化しな
かった一様伸びが急激に改善されはじめ、約５００℃で
５．２％と５％を越えていることがわかる。As a test method, a tensile test specified in JIS G 3109 was performed on each steel material, and tensile strength, yield point and elongation were measured. Here, uniform elongation is 200 mm between gauge points
The load and elongation were read for each 0.02 mm (0.1% strain amount) using a special elongation gauge of No. 3, and a load-elongation curve until the constriction (drawing) occurred in the steel material was created and read. The presence or absence of the constriction was confirmed by temporarily stopping the load and using a micrometer to examine the change in the steel material diameter. The result is shown in FIG. As shown in the figure,
It can be seen that the uniform elongation, which has not changed so much from the tempering temperature of around 500 ° C., starts to be rapidly improved and exceeds 5.2% and 5.2% at approximately 500 ° C.
【００１５】（試験例２）次に、前記試験例１の結果を
踏まえて、一様伸びに強い影響を与える焼戻し温度を高
温側に移行させるべく化学組成を変更し、化学成分が
Ｃ：０．５６、Ｓｉ：１．３９、Ｍｎ：０．７０、Ｃ
ｒ：０．６４（全て重量％）で、１０ｍｍφの鋼素材を
９．１５ｍｍφに異形加工したものを前記製造方法で作
製した。本試験例でも焼戻し温度を種々変え、各温度条
件で得られた鋼材の機械的特性について試験例１と同様
の試験を行った。その結果を図２に示す。(Test Example 2) Next, based on the results of Test Example 1, the chemical composition was changed so as to shift the tempering temperature which strongly affects uniform elongation to the high temperature side, and the chemical composition was C: 0. .56, Si: 1.39, Mn: 0.70, C
With r: 0.64 (all weight%), a steel material of 10 mmφ was deformed to 9.15 mmφ and manufactured by the above manufacturing method. Also in this test example, the tempering temperature was variously changed, and the same test as in test example 1 was performed on the mechanical properties of the steel material obtained under each temperature condition. The result is shown in FIG.
【００１６】（試験例３）さらに、試験例２と同じ目的
で、化学成分がＣ：０．４８、Ｓｉ：１．１１、Ｍｎ：
０．７３、Ｃｒ：０．７２（全て重量％）で１０ｍｍφ
の鋼素材を９．１５ｍｍφに異形加工たものを前記製造
方法で作製した。焼戻し温度を変え、各温度条件で得ら
れた鋼材の機械的特性について試験例１と同様の試験を
行った。その結果を試験例２と同じく図２に示す。(Test Example 3) Further, for the same purpose as in Test Example 2, the chemical components were C: 0.48, Si: 1.11 and Mn:
0.73, Cr: 0.72 (all weight%) 10 mmφ
The steel material of No. 1 was deformed to a diameter of 9.15 mm and manufactured by the above manufacturing method. The tempering temperature was changed, and the same test as in Test Example 1 was performed on the mechanical properties of the steel material obtained under each temperature condition. The results are shown in FIG. 2 as in Test Example 2.
【００１７】同図に示すように、いずれの試験例の場合
も焼戻し温度５００℃のとき、一様伸びは５．０％を越
えており、引張強度も十分で優れた機械的特性であるこ
とが確認された。又、同温度６５０℃のとき、一様伸び
は６．９％と大きく改善されているが、引張強さはJIS
G 3109のＤ種規格値の下限である１４２０Ｎ／ｍｍ2近
くとなっている。As shown in the figure, in all the test examples, the uniform elongation exceeds 5.0% at the tempering temperature of 500 ° C., and the tensile strength is sufficient and the mechanical properties are excellent. Was confirmed. At the same temperature of 650 ° C, the uniform elongation is greatly improved to 6.9%, but the tensile strength is JIS
It is close to 1420 N / mm 2, which is the lower limit of the D class standard value of G 3109.
【００１８】[0018]
【発明の効果】以上説明したように、本発明鋼材によれ
ば、現在慣用ＰＣ鋼棒の機械的特性を維持し、かつ一様
伸び特性を大きく改善できる。従って、本鋼材をＰＣく
いやＰＣ柱等の構造物において主筋に使用すると、曲げ
靱性改善の有効な手段となる。又、遅れ破壊特性の向上
によりプレストレストコンクリート構造物の品質向上に
も大きな効果を奏するため、構造物の耐震性向上に資す
ることが期待できる。As described above, according to the steel material of the present invention, the mechanical properties of the currently used conventional PC steel bar can be maintained and the uniform elongation property can be greatly improved. Therefore, when the present steel material is used as a main bar in a structure such as a PC pile or a PC column, it becomes an effective means for improving bending toughness. In addition, since the delayed fracture characteristics are improved, the prestressed concrete structure is greatly improved in quality, which can be expected to contribute to the improvement of the earthquake resistance of the structure.
【図１】焼戻し温度と鋼材の機械的特性の関係を示すグ
ラフである。FIG. 1 is a graph showing the relationship between tempering temperature and mechanical properties of steel materials.
【図２】焼戻し温度と鋼材の機械的特性の関係を示すグ
ラフである。FIG. 2 is a graph showing the relationship between tempering temperature and mechanical properties of steel materials.
Claims (2)
０〜１．５０、Ｍｎ：０．５０〜０．９０、Ｃｒ：０．
５０〜０．８０（全て重量％）を含有し、引張強さが１
４２０Ｎ／ｍｍ2 以上であって、一様伸びが５％以上で
あることを特徴とする一様伸びに優れたＰＣ用鋼材。1. C: 0.45 to 0.60, Si: 1.0
0 to 1.50, Mn: 0.50 to 0.90, Cr: 0.
Contains 50 to 0.80 (all weight%) and has a tensile strength of 1
Steel for PC excellent in uniform elongation, which is 420 N / mm 2 or more and uniform elongation is 5% or more.
Ｃ鋼材の製造方法において、Ｃ：０．４５〜０．６０、
Ｓｉ：１．００〜１．５０、Ｍｎ：０．５０〜０．９
０、Ｃｒ：０．５０〜０．８０（全て重量％）を含有す
る鋼材を、５００℃以上６５０℃以下の焼戻し温度まで
加熱後、急冷することを特徴とするＰＣ用鋼材の製造方
法。2. P manufactured through a quenching and tempering process
In the method for producing C steel material, C: 0.45 to 0.60,
Si: 1.00 to 1.50, Mn: 0.50 to 0.9
A steel material containing 0, Cr: 0.50 to 0.80 (all weight%) is heated to a tempering temperature of 500 ° C. or higher and 650 ° C. or lower and then rapidly cooled, thereby producing a steel material for PC.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17274393A JPH073396A (en) | 1993-06-17 | 1993-06-17 | Steel for pc excellent in uniform elongation and production thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17274393A JPH073396A (en) | 1993-06-17 | 1993-06-17 | Steel for pc excellent in uniform elongation and production thereof |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH073396A true JPH073396A (en) | 1995-01-06 |
Family
ID=15947500
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17274393A Pending JPH073396A (en) | 1993-06-17 | 1993-06-17 | Steel for pc excellent in uniform elongation and production thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH073396A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6324471B1 (en) | 1999-04-30 | 2001-11-27 | Honda Giken Kogyo Kabushiki Kaisha | Map information display system for movable bodies |
-
1993
- 1993-06-17 JP JP17274393A patent/JPH073396A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6324471B1 (en) | 1999-04-30 | 2001-11-27 | Honda Giken Kogyo Kabushiki Kaisha | Map information display system for movable bodies |
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