JP3684186B2 - High-strength PC strand, manufacturing method thereof, PC floor slab using the same, concrete structure - Google Patents
High-strength PC strand, manufacturing method thereof, PC floor slab using the same, concrete structure Download PDFInfo
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- JP3684186B2 JP3684186B2 JP2001304775A JP2001304775A JP3684186B2 JP 3684186 B2 JP3684186 B2 JP 3684186B2 JP 2001304775 A JP2001304775 A JP 2001304775A JP 2001304775 A JP2001304775 A JP 2001304775A JP 3684186 B2 JP3684186 B2 JP 3684186B2
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- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B1/00—Constructional features of ropes or cables
- D07B1/06—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core
- D07B1/0693—Ropes or cables built-up from metal wires, e.g. of section wires around a hemp core having a strand configuration
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2001—Wires or filaments
- D07B2201/2009—Wires or filaments characterised by the materials used
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2201/00—Ropes or cables
- D07B2201/20—Rope or cable components
- D07B2201/2015—Strands
- D07B2201/2024—Strands twisted
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2205/00—Rope or cable materials
- D07B2205/30—Inorganic materials
- D07B2205/3021—Metals
- D07B2205/3025—Steel
- D07B2205/3046—Steel characterised by the carbon content
- D07B2205/3057—Steel characterised by the carbon content having a high carbon content, e.g. greater than 0,8 percent respectively SHT or UHT wires
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B2501/00—Application field
- D07B2501/20—Application field related to ropes or cables
- D07B2501/2015—Construction industries
- D07B2501/2023—Concrete enforcements
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- Ropes Or Cables (AREA)
- Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
- Heat Treatment Of Strip Materials And Filament Materials (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は熱間圧延された線材を伸線加工によって、より細い線径に加工し、これらの複数本を撚って製造される、溶融亜鉛めっき線、ロープ、ACSR線、PC鋼撚り線などの撚り線に関する。
【０００２】
【従来の技術】
PCストランドは、通常、JIS G3502に規定されるピアノ線材にパテンティングを行った後伸線し、その後300〜350℃の温度範囲でホットストレッチングを施す方法で製造されている。また、PCストランドに用いられているものはJISに規定される規格荷重を満たすものが使用されているのみである。
特開昭59-179755号公報には鋼組成を制御すること、具体的にはCu、Ni、Wを添加し、Si含有量を低減することにより、塩分環境におけるＰＣ鋼線の腐食を抑制することが記載されている。しかし、Si含有量を低く抑えることは、PC鋼線の高強度化およびリラクゼーション値の低下を招くもので、高強度化とは異なる目的でなされた発明である。
【０００３】
最近のコンクリートの強度上昇やPCストランドを取り扱う時の施工性の向上、つまり、同じ引張強度でストランド径の小さいPCストランドあるいは同じストランド径のPCストランドでも使用するピッチが広げられる高強度のPCストランドの発明が期待されている。
【０００４】
【発明が解決しようとする課題】
以上、述べたように従来の技術では、標準径の太い高強度のPCストランドより線を製造することは不可能であった。本発明は、上記従来法の問題点を解決し、従来に比べより高強度なPCストランドならびに高強度PCストランドを用いた構造物を提供することを課題とする。
【０００５】
【課題を解決するための手段】
本発明者らは、前述の課題を解決するため鋭意研究を重ね、高強度PCストランドの成分系、サイズ、およびその製造方法ならびに用途を見出したものであり、その要旨は特許請求の範囲に記載した下記の内容である。
（１）JIS規格の19本撚りで構成される標準径が19.3mmであって、総断面積が240〜250mm2であり、引張荷重が550kN以上であることを特徴とする高強度PCストランド。
（２）JIS規格の19本撚りで構成される標準径が21.8mmであって、総断面積が310〜320mm2であり、引張荷重が700kN以上であることを特徴とする高強度PCストランド。
【０００６】
（３）PC ストランドを構成するワイヤの線径が、 5.40 ± 0.2mm 、 2.74 ± 0.2mm 、 4.88 ± 0.2mm の 3 種類であって、それぞれのワイヤをストランドの中心から 1 本、９本、９本ずつ用いることを特徴とする（１）に記載の高強度 PC ストランド。
（４）PC ストランドを構成するワイヤの線径が、 6.12 ± 0.2mm 、 3.12 ± 0.2mm 、 5.56 ± 0.2mm の 3 種類であって、それぞれのワイヤをストランドの中心から 1 本、９本、９本ずつ用いることを特徴とする（２）に記載の高強度 PC ストランド。
【０００７】
（５）質量％で、C：0.87〜1.3%、Si：0.5〜1.2%、Mn：0.1〜1.0%を含み、残部をＦｅおよび不可避的不純物からなる鋼を用いることを特徴とする（１）乃至（４）に記載の高強度PCストランド。
（６）線材の強度を高めるために（５）に記載の鋼成分に加え、質量％で、Cr：0.05〜1.5％、Ni：0.03〜1.0％、V：0.001〜0.5％、Nb：0.001〜0.5％、Mo：0.001〜0.5％の１種以上を含むことを特徴とする（１）乃至（４）に記載の高強度PCストランド。
【０００８】
（７）線材の耐腐食特性を高めるために（５）または（６）に記載の鋼成分に加え、質量％で、Cu：0.01〜1.0％を含むことを特徴とする（１）乃至（４）に記載の高強度PCストランド。
（８）線材の延性を高めるために（５）乃至（７）に記載の鋼成分に加え、質量％で、Al：0.001〜0.1％、B：0.0005〜0.1％を含むことを特徴とする（１）乃至（４）に記載の高強度PCストランド。
【０００９】
（９）（５）乃至（８）の鋼成分に加え、質量％で、P：0.03％以下、S：0.03％以下を含むことを特徴とする（１）乃至（４）に記載の高強度PCストランド。
（１０）（５）乃至（９）の鋼成分からなり、線径６mm以上、16mm以下、引張強さ1400MPa以上、初析セメンタイトの最大サイズが0.5mm以下であることを特徴とする高強度PCストランド用熱間圧延線材。
【００１０】
（１１）（３）に記載した径の鋼線を撚り合わせ、ヒートストレッチング処理あるいはブルーイング処理を350℃〜400℃で行い、引張荷重が550kN 以上であるPCストランドとすることを特徴とする高強度PCストランドの製造方法。
（１２）（４）に記載した径の鋼線を撚り合わせ、ヒートストレッチング処理あるいはブルーイング処理を350℃〜400℃で行い、引張荷重が700kN 以上であるPCストランドとすることを特徴とする高強度PCストランドの製造方法。
【００１１】
（１３）（１）乃至（９）のPCストランドを用いたことを特徴とするPC床版。
（１４）（１）乃至（９）のPCストランドを用いたことを特徴とするコンクリート構造物。
【００１２】
まず、鋼組成の限定理由について説明する。成分は全て質量％である。
Cは強化に有効な元素であり高強度の鋼線を得るためにはC量を0.87％以上とすることが必要であるが、高すぎると初析セメンタイトが析出しやすいため、延性が低下し、かつ伸線性が劣化するのでその上限は1.3％とする。
Siは鋼の脱酸のために必要な元素であり、従ってその含有量があまりに少ないとき、脱酸効果が不十分になるので0.5％以上添加する。また、Siは熱処理後に形成されるパーライト中のフェライト相に固溶しパテンティング後の強度を上げるが、反面、熱処理性を阻害するので1.2％以下とする。
【００１３】
Mnは鋼の焼き入れ性を確保するために0.1％以上のMnを添加する。しかし、多量のMnの添加は、パテンティングの際の変態時間を長くしすぎるので1.0％以下とする。
Crは鋼の強度を高めるために添加する。添加する場合には、その効果の発揮される0.05%以上添加し、鋼線の延性を引き起こすことの無い1.5%以下とする。
【００１４】
Niは鋼の強度を上げる効果がある。添加する場合にはその添加効果のある0.03％以上添加する。しかし、添加量が多くなりすぎると延性が低下するので1.0％以下とする。
Vは鋼の強度を上げる効果がある。添加する場合にはその添加効果のある0.001％以上添加する。しかし、添加量が多くなり過ぎると延性が低下するので上限を0.5％とする。
【００１５】
Nbは鋼の強度を上げる効果がある。添加する場合には、その添加効果のある0.001％以上添加する。しかし、添加量が多くなり過ぎると延性が低下するので上限を0.5％とする。
Cuは耐食性、腐食疲労特性を向上するために添加する。添加する場合には、その添加効果のある0.01％添加する。しかし、多量の添加をすると熱間圧延の際に脆化しやすくなるので上限を1.0％とする。
【００１６】
Alは脱酸元素であると同時にオーステナイト化したときのγ粒径を微細にパテンティング後の絞りを向上する。添加する時はその効果が発揮される0.001％以上添加する。しかし、多量の添加は介在物の量を増加するため、上限を0.1％とする。
Ｂはもオーステナイト化した際のγ粒径を細かくする効果がある。これにより絞りなどの延性を向上する。このため、添加する場合にはその効果のある、0.0005％以上添加する。しかし、0.1％を越えて添加すると熱処理によって変態させる際の変態時間が長くなり過ぎるため、上限を0.1％とする。
【００１７】
従来の極細鋼線と同様に延性を確保するためSの含有量を0.03%以下とし、PもSと同様に線材の延性を害するのでその含有量を0.03%以下とするのが望ましい。
PCストランドの規格は引張荷重によって決められる。従って、引張強さと断面積の積できまることになる。本発明者らは、より高強度のPCストランドを開発するに当たって、引張強さと断面積の取り方を検討し、請求項1、2に記載の範囲に規定することで、従来にない高強度のPCストランドを得られることを見出した。
【００１８】
すなわち、19.3mmの場合には断面積が240mm2以上、250mm2以下となるように調整する。240mm2未満では引張強さを個々の素線で確保することが難しく、250mm2を越えるとPCストランドの標準径を19.3mmに調整することが難しくなる。また、引張荷重を550kN未満では従来のPCと比べて、挿入ピッチの拡大や使用する径のサイズダウンが出来ないためメリットがあまり得られない。このため引張荷重は550kN以上に調整する。19.3mmの19本撚りPCストランドの素線の線径の組み合わせは5.40±0.2mm、4.88±0.2mm、2.74±0.2mmの範囲に調整する。このサイズのバランスを大きくなりすぎても小さくなりすぎても標準線径を19.3mmとすることが難しくなる。
21.8mmの場合には断面積が310mm2以上、320mm2以下となるように調整する。310mm2未満では引張強さを個々の素線で確保することが難しく、320mm2を越えるとPCストランドの標準径を21.8mmに調整することが難しくなる。また、引張荷重を700kN未満では従来のPCと比べて、挿入ピッチの拡大や使用する径のサイズダウンが出来ないためメリットがあまり得られない。このため引張荷重は700kN以上に調整する。21.8mmの19本撚りPCストランドの素線の線径の組み合わせは6.12±0.2mm、5.56±0.2mm、3.12±0.2mmの範囲に調整する。このサイズのバランスを大きくなりすぎても小さくなりすぎても標準線径を19.3mmとすることが難しくなる。
【００１９】
このような高強度PCストランドに用いる線材は、線径が少なくとも6mm以上必要であり、16mmを越えると一般的なドラム式の伸線機で伸線が困難になるので16mm以下の線径に調整する。また、高強度PCストランドを得るためには、伸線加工前の引張強さを少なくとも1400MPa以上に調整する必要がある。また、この線材中に存在する初析セメンタイトの最大のサイズを0.5mm以下としなければ、伸線加工のワイヤの性質が大きく劣化する。このため線材中に存在する初析セメンタイトの最大サイズを0.5mmとする。
【００２０】
伸線加工によって所定の強度に調整されたPCストランドは、撚り線加工の後にブルーイング処理されるが、延性を回復させるためには、少なくとも330℃以上の温度でブルーイング処理或いはヒートストレッチング処理を行う必要がある。また400℃を越えるとPCストランドの強度が大きく低下するので400℃以下の温度でブルーイング処理あるいはヒートストレッチング処理を行う必要がある。
本発明のPCストランドはPC床版に用いた場合に、挿入ピッチを広く取っても強度が高いために従来材と同じ強度、ならびに荷重に対するたわみ量を確保する設計が可能となる。
【００２１】
【発明の実施の形態】
以下に実施例に基づいて本発明の効果を記す。表1に試作に用いた供試鋼の化学成分を示す。本発明例であるA-1、A-2は本発明に従い調整されているが比較例のB-1は本発明の範囲とは異なっている。
表１に示す鋼を溶製し、連続鋳造で鋳造した後、熱間圧延でビレットとした。このビレットを再加熱後、線材圧延のより直径7〜14mmの線材とし、直接溶融塩に浸漬してパテンティング処理を行った。得られたワイヤの引張強さを表２に示す。本発明例A-1の線材は、いずれの線径においても1400MPa以上の強度に調整されている。一方、比較例のB-1を用いて製造した13mmの線材は本発明例と比較して引張強さが低い結果である。
【００２２】
【表１】
次に、表２のA-1の線材に伸線加工を行い、表３に示す各線径のワイヤを製造し、撚り線加工を行い所定の径のPCストランドとした。このPCストランドに370℃のブルーイング処理を行い高強度PCストランドとした。本発明の高強度PCストランドは、素線の線径、ワイヤの断面の総面積ならびに引張荷重が本発明に従って調整されている。一方、比較例のPCストランドはJISに規定された強度を有するが、本発明材に比べ低い強度となっている。
【００２４】
【表２】
【表３】
最後に高強度PCストランドをPC床版に用いた場合について説明する。JIS規格の21.8mmのPCストランドを25cmピッチで挿入した床版と本発明材の21.8mmのPCストランドを28.6mmピッチで挿入し、それぞれ同一のプレストレスをコンクリートに与え裁荷試験を行い、PC床版の強度を調査した。その結果、どちらも最大荷重200kNをかけてもクラックの発生はなく、たわみ量もほぼ同一かむしろ本発明例の方が優れる結果となった。その結果を表４に示す。
【００２７】
【表４】
【発明の効果】
本発明を用いることで、高強度のPCストランドが得られ、また、このPCストランドをコンクリートに用いて、施工性に優れる構造物を製造することが可能となるなど、産業上極めて有用な効果を奏する。[0001]
BACKGROUND OF THE INVENTION
The present invention is a hot-rolled wire processed into a thinner wire diameter by wire drawing, and manufactured by twisting a plurality of these, hot-dip galvanized wire, rope, ACSR wire, PC steel stranded wire, etc. Related to stranded wire.
[0002]
[Prior art]
The PC strand is usually manufactured by a method in which a piano wire specified in JIS G3502 is subjected to patenting and then drawn, followed by hot stretching in a temperature range of 300 to 350 ° C. Moreover, the thing currently used for the PC strand only satisfy | fills the standard load prescribed | regulated to JIS.
In JP-A-59-179755, the corrosion of PC steel wires in a salt environment is suppressed by controlling the steel composition, specifically by adding Cu, Ni, W and reducing the Si content. It is described. However, keeping the Si content low results in an increase in the strength of the PC steel wire and a decrease in the relaxation value, and is an invention made for a purpose different from the increase in the strength.
[0003]
Recent improvement in concrete strength and improvement in workability when handling PC strands, that is, high-strength PC strands with the same tensile strength and small strand diameters or high-strength PC strands that can be used even with PC strands with the same strand diameter. Invention is expected.
[0004]
[Problems to be solved by the invention]
As described above, it has been impossible to produce a wire from a high-strength PC strand having a large standard diameter by the conventional technique. An object of the present invention is to solve the above-mentioned problems of the conventional method, and to provide a structure using a PC strand having a higher strength than the conventional one and a high-strength PC strand.
[0005]
[Means for Solving the Problems]
The inventors of the present invention have made extensive studies to solve the above-mentioned problems, and have found a component system, a size, and a production method and use of a high-strength PC strand, the gist of which is described in the claims It is the following contents.
(1) A high-strength PC strand characterized by a JIS standard 19-strand standard diameter of 19.3 mm, a total cross-sectional area of 240 to 250 mm 2 and a tensile load of 550 kN or more.
(2) the standard diameter composed of twisted nineteen JIS standards a 21.8 mm, the total cross-sectional area is 310～320Mm 2, high-strength PC strand tensile load, characterized in that at least 700KN.
[0006]
(3) There are three types of wire diameters that make up the PC strand: 5.40 ± 0.2mm , 2.74 ± 0.2mm , 4.88 ± 0.2mm . Each wire is 1 , 9, and 9 from the center of the strand. The high-strength PC strand according to (1), which is used one by one .
(4) There are three types of wire diameters that make up the PC strand: 6.12 ± 0.2mm , 3.12 ± 0.2mm , 5.56 ± 0.2mm . Each wire is 1 , 9, and 9 from the center of the strand. The high-strength PC strand according to (2), which is used one by one .
[0007]
(5) It is characterized by using a steel containing C: 0.87 to 1.3%, Si: 0.5 to 1.2%, Mn: 0.1 to 1.0%, the balance being Fe and inevitable impurities in mass% (1) Thru | or the high intensity | strength PC strand as described in (4).
(6) In order to increase the strength of the wire rod, in addition to the steel components described in (5), in mass%, Cr: 0.05-1.5%, Ni: 0.03-1.0%, V: 0.001-0.5%, Nb: 0.001- The high-strength PC strand according to any one of (1) to (4), including one or more of 0.5% and Mo: 0.001 to 0.5%.
[0008]
(7) In order to improve the corrosion resistance of the wire rod, in addition to the steel components described in (5) or (6), Cu: 0.01 to 1.0% is contained in mass% (1) to (4) High-strength PC strands as described in).
(8) In order to increase the ductility of the wire, in addition to the steel components described in (5) to (7), in mass%, Al: 0.001 to 0.1%, B: 0.0005 to 0.1% is included ( The high-strength PC strand according to 1) to (4).
[0009]
(9) In addition to the steel components of (5) to (8), the high strength according to (1) to (4), including P: 0.03% or less and S: 0.03% or less in mass% PC strand.
(10) A high-strength PC comprising steel components (5) to (9), having a wire diameter of 6 mm or more and 16 mm or less, a tensile strength of 1400 MPa or more, and a maximum size of proeutectoid cementite of 0.5 mm or less. Hot rolled wire rod for strands.
[0010]
(11) A steel strand having the diameter described in (3) is twisted, and heat stretching treatment or bluing treatment is performed at 350 ° C. to 400 ° C. to form a PC strand having a tensile load of 550 kN or more. High strength PC strand manufacturing method.
(12) The steel wires having the diameters described in (4) are twisted together, heat stretch treatment or bluing treatment is performed at 350 ° C to 400 ° C, and a PC strand having a tensile load of 700 kN or more is obtained. High strength PC strand manufacturing method.
[0011]
(13) A PC slab using the PC strands of (1) to (9).
(14) A concrete structure using the PC strand of (1) to (9).
[0012]
First, the reason for limiting the steel composition will be described. All components are in weight percent.
C is an element effective for strengthening, and in order to obtain a high-strength steel wire, the C content needs to be 0.87% or more. However, if it is too high, proeutectoid cementite is likely to precipitate, resulting in reduced ductility. In addition, since the drawability deteriorates, the upper limit is made 1.3%.
Si is an element necessary for deoxidation of steel. Therefore, when its content is too small, the deoxidation effect becomes insufficient, so 0.5% or more is added. In addition, Si dissolves in the ferrite phase in the pearlite formed after the heat treatment and increases the strength after patenting, but on the other hand, the heat treatment property is hindered, so the content is made 1.2% or less.
[0013]
Mn is added in an amount of 0.1% or more in order to ensure the hardenability of the steel. However, the addition of a large amount of Mn makes the transformation time during patenting too long, so it is made 1.0% or less.
Cr is added to increase the strength of the steel. When added, 0.05% or more where the effect is exerted is added to 1.5% or less which does not cause ductility of the steel wire.
[0014]
Ni has the effect of increasing the strength of the steel. If added, 0.03% or more is added because of its effect. However, if the amount added is too large, the ductility is lowered, so 1.0% or less.
V has the effect of increasing the strength of the steel. When adding, 0.001% or more which has the effect of the addition is added. However, if the amount added is too large, the ductility decreases, so the upper limit is made 0.5%.
[0015]
Nb has the effect of increasing the strength of the steel. When added, 0.001% or more with the addition effect is added. However, if the amount added is too large, the ductility decreases, so the upper limit is made 0.5%.
Cu is added to improve corrosion resistance and corrosion fatigue characteristics. When added, 0.01% with the effect of the addition is added. However, if a large amount is added, it tends to become brittle during hot rolling, so the upper limit is made 1.0%.
[0016]
Al is a deoxidizing element and at the same time improves the drawing after patenting finely the γ grain size when austenitized. When added, 0.001% or more is added to achieve the effect. However, the addition of a large amount increases the amount of inclusions, so the upper limit is made 0.1%.
B also has the effect of reducing the γ grain size when austenitized. This improves the ductility of the aperture. For this reason, when adding, 0.0005% or more which has the effect is added. However, if added over 0.1%, the transformation time during transformation by heat treatment becomes too long, so the upper limit is made 0.1%.
[0017]
In order to ensure ductility as in the case of conventional ultrafine steel wires, the S content is set to 0.03% or less, and P also impairs the ductility of the wire material in the same manner as S. Therefore, the content is preferably set to 0.03% or less.
The standard of the PC strand is determined by the tensile load. Therefore, the product of tensile strength and cross-sectional area can be achieved. In developing a higher-strength PC strand, the present inventors studied how to take a tensile strength and a cross-sectional area, and by defining in the range described in claims 1 and 2, an unprecedented high-strength. We found that PC strands can be obtained.
[0018]
That is, in the case of 19.3 mm, the cross-sectional area is adjusted to be 240 mm 2 or more and 250 mm 2 or less. If it is less than 240 mm2, it is difficult to secure the tensile strength with individual strands, and if it exceeds 250 mm2, it is difficult to adjust the standard diameter of the PC strand to 19.3 mm. If the tensile load is less than 550kN, the insertion pitch cannot be increased and the diameter to be used cannot be reduced compared to conventional PCs. Therefore, the tensile load is adjusted to 550kN or more. The combination of the wire diameters of the 19.3mm 19-strand PC strand is adjusted to the range of 5.40 ± 0.2mm, 4.88 ± 0.2mm, 2.74 ± 0.2mm. If the balance of this size becomes too large or too small, it becomes difficult to set the standard wire diameter to 19.3 mm.
In the case of 21.8 mm, the cross-sectional area is adjusted to be 310 mm 2 or more and 320 mm 2 or less. If it is less than 310 mm 2 , it is difficult to secure the tensile strength with individual strands, and if it exceeds 320 mm 2 , it is difficult to adjust the standard diameter of the PC strand to 21.8 mm. Also, if the tensile load is less than 700kN, the insertion pitch cannot be increased and the diameter to be used cannot be reduced compared to conventional PCs. Therefore, the tensile load is adjusted to 700kN or more. The combination of the wire diameters of the 21.8mm 19-strand PC strand is adjusted to the range of 6.12 ± 0.2mm, 5.56 ± 0.2mm, 3.12 ± 0.2mm. If the balance of this size becomes too large or too small, it becomes difficult to set the standard wire diameter to 19.3 mm.
[0019]
The wire used for such high-strength PC strands must have a wire diameter of at least 6mm. If it exceeds 16mm, it will be difficult to draw with a general drum type wire drawing machine. To do. In order to obtain a high-strength PC strand, it is necessary to adjust the tensile strength before wire drawing to at least 1400 MPa. Also, unless the maximum size of pro-eutectoid cementite present in the wire is 0.5 mm or less, the properties of the wire for wire drawing are greatly deteriorated. For this reason, the maximum size of pro-eutectoid cementite present in the wire is 0.5 mm.
[0020]
PC strands adjusted to a predetermined strength by wire drawing are subjected to blueing treatment after stranded wire processing. To restore ductility, blue stranding or heat stretching treatment is performed at a temperature of at least 330 ° C. Need to do. If the temperature exceeds 400 ° C., the strength of the PC strand is greatly reduced. Therefore, it is necessary to perform blueing treatment or heat stretching treatment at a temperature of 400 ° C. or lower.
When the PC strand of the present invention is used for a PC floor slab, the strength is high even when the insertion pitch is wide, so that the same strength as the conventional material and the design for securing the amount of deflection with respect to the load can be achieved.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
The effects of the present invention will be described below based on examples. Table 1 shows the chemical composition of the test steel used in the trial production. The inventive examples A-1 and A-2 are prepared according to the present invention, but the comparative example B-1 is different from the scope of the present invention.
The steel shown in Table 1 was melted and cast by continuous casting, and then billeted by hot rolling. This billet was reheated, and then a wire having a diameter of 7 to 14 mm was formed by wire rolling, and was directly immersed in molten salt for a patenting treatment. Table 2 shows the tensile strength of the obtained wire. The wire material of Invention Example A-1 is adjusted to a strength of 1400 MPa or more at any wire diameter. On the other hand, the 13 mm wire manufactured using B-1 of the comparative example has a lower tensile strength than the inventive example.
[0022]
[Table 1]
Next, wire drawing of A-1 in Table 2 was performed to produce wires with various wire diameters shown in Table 3, and twisted wire processing was performed to obtain PC strands having a predetermined diameter. This PC strand was subjected to a 370 ° C. bluing treatment to obtain a high-strength PC strand. In the high-strength PC strand of the present invention, the wire diameter, the total cross-sectional area of the wire, and the tensile load are adjusted according to the present invention. On the other hand, the PC strand of the comparative example has the strength specified by JIS, but has a lower strength than the material of the present invention.
[0024]
[Table 2]
[Table 3]
Finally, a case where a high-strength PC strand is used for a PC floor slab will be described. Insert a slab of 21.8mm PC strand of JIS standard at 25cm pitch and 21.8mm PC strand of the material of the present invention at 28.6mm pitch, give each concrete the same pre-stress to the concrete and conduct a load test. The strength of the slab was investigated. As a result, in both cases, even when a maximum load of 200 kN was applied, no crack was generated, and the amount of deflection was almost the same, or rather the example of the present invention was superior. The results are shown in Table 4.
[0027]
[Table 4]
【The invention's effect】
By using the present invention, a high-strength PC strand can be obtained, and the use of this PC strand in concrete makes it possible to produce a structure excellent in workability. Play.
Claims (14)
C：0.87〜1.3%、
Si：0.5〜1.2%、
Mn：0.1〜1.0%を含み、残部をＦｅおよび不可避的不純物からなる鋼を用いることを特徴とする請求項１乃至請求項４に記載の高強度PCストランド。% By mass
C: 0.87 to 1.3%
Si: 0.5-1.2%
The high-strength PC strand according to any one of claims 1 to 4, wherein steel comprising Mn: 0.1 to 1.0% and the balance being Fe and inevitable impurities is used.
Cr：0.05〜1.5％、
Ni：0.03〜1.0％、
V：0.001〜0.5％、
Nb：0.001〜0.5％、
Mo：0.001〜0.5％の１種以上を含むことを特徴とする請求項１乃至請求４に記載の高強度PCストランド。In order to increase the strength of the wire, in addition to the steel component according to claim 5, in mass%,
Cr: 0.05-1.5%
Ni: 0.03-1.0%,
V: 0.001-0.5%
Nb: 0.001 to 0.5%
The high-strength PC strand according to any one of claims 1 to 4, comprising one or more of Mo: 0.001 to 0.5%.
Al：0.001〜0.1％、
B：0.0005〜0.1％を含むことを特徴とする請求項１乃至請求項４に記載の高強度PCストランド。In order to enhance the ductility of the wire rod, in addition to the steel components according to claim 5 to claim 7,
Al: 0.001 to 0.1%,
The high-strength PC strand according to any one of claims 1 to 4, wherein B: 0.0005 to 0.1% is contained.
P：0.03％以下、
S：0.03％以下を含むことを特徴とする請求項１乃至請求項４に記載の高強度PCストランド。In addition to the steel components of claims 5 to 8, in mass%,
P: 0.03% or less,
The high-strength PC strand according to any one of claims 1 to 4, comprising S: 0.03% or less.
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| JP2007224453A (en) * | 2006-02-23 | 2007-09-06 | Sumitomo Denko Steel Wire Kk | High-strength pc steel strand, method for producing the same, and concrete construct |
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| JP6115809B2 (en) * | 2013-01-17 | 2017-04-19 | 住友電工スチールワイヤー株式会社 | High-strength PC steel strand and its manufacturing method |
| CN109343591B (en) * | 2018-09-15 | 2022-08-19 | 北京市建筑工程研究院有限责任公司 | Post-tensioning pre-stress tensioning fine control device and method based on intelligent steel strand |
| CN114657471B (en) * | 2022-03-27 | 2022-12-23 | 中天钢铁集团有限公司 | Production method of low-carbon energy-saving wire rod for bridge cable rope with pressure of not less than 2060MPa |
| CN115505683A (en) * | 2022-08-25 | 2022-12-23 | 包头钢铁（集团）有限责任公司 | Steel dehydrogenation control method for hypereutectoid bridge prestressed steel strand |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2007224453A (en) * | 2006-02-23 | 2007-09-06 | Sumitomo Denko Steel Wire Kk | High-strength pc steel strand, method for producing the same, and concrete construct |
| US7861507B2 (en) | 2006-02-23 | 2011-01-04 | Sumitomo (Sei) Steel Wire Corp. | High-strength prestressing strand, method for manufacturing the same, and concrete construction using the same |
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