JP2003321741A - High strength pc steel bar having high temperature relaxation property and production method therefor - Google Patents
High strength pc steel bar having high temperature relaxation property and production method thereforInfo
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- JP2003321741A JP2003321741A JP2002125404A JP2002125404A JP2003321741A JP 2003321741 A JP2003321741 A JP 2003321741A JP 2002125404 A JP2002125404 A JP 2002125404A JP 2002125404 A JP2002125404 A JP 2002125404A JP 2003321741 A JP2003321741 A JP 2003321741A
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- steel
- strength
- steel bar
- temperature relaxation
- relaxation characteristics
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Abstract
Description
【発明の詳細な説明】Detailed Description of the Invention
【０００１】[0001]
【発明の属する技術分野】本発明はＰＣ鋼棒およびその
製造方法に関し、特にミクロ組織の調整により高温リラ
クセーション特性に優れたものに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PC steel rod and a method for producing the same, and more particularly to a steel rod excellent in high temperature relaxation characteristics by adjusting a microstructure.
【０００２】[0002]
【従来の技術】ＰＣ鋼棒は、プレストレスコンクリート
に用いられる鋼強度部材で、ＪＩＳＧ３１０９「ＰＣ鋼
棒」、ＪＩＳＧ３１３７「細径異形ＰＣ鋼棒」において
成分組成、引張り強さ、リラクセーション特性などが規
格化されている。2. Description of the Related Art PC steel rods are steel strength members used in prestressed concrete, and the composition, tensile strength, relaxation characteristics, etc. of JIS G3109 "PC steel rods" and JIS G3137 "small diameter deformed PC steel rods" are standard. Has been converted.
【０００３】リラクセーション特性はＰＣ鋼棒のコンク
リート中での応力緩和特性を示すものとされ、上記規格
においては常温における特性が規定されている。The relaxation property is supposed to indicate the stress relaxation property of PC steel rod in concrete, and the property at room temperature is specified in the above standard.
【０００４】しかしながら、最近、プレストレスコンク
リートパイルあるいはポールの製造時のコンクリートの
養生では、其の期間を短縮すべく１８０〜２００℃で約
１０気圧のオートクレープ養生が用いられることによ
り、高温でのＰＣ鋼棒のリラクセーション抑制が課題で
種々の技術が提案されている。However, recently, in the curing of concrete during the production of prestressed concrete piles or poles, autoclave curing of about 10 atm at 180 to 200 ° C. is used in order to shorten the period, so that the curing at high temperature can be performed. Various techniques have been proposed with the problem of suppressing relaxation of PC steel rods.
【０００５】特公平３−７９４１０号公報には焼戻し時
に２％以下の微小な曲げ歪を付与することが記載され、
特開平３−２８３５１号公報にはＰＣ鋼棒を４００〜９
００℃で加工、または塑性加工を付与しながら昇温し逆
変態により超微細組織とすることが、更に特開昭５８−
１２０７３８号公報には湿式直線機により矯直時に冷却
することが記載されている。Japanese Patent Publication No. 3-79410 describes that a minute bending strain of 2% or less is applied during tempering.
Japanese Unexamined Patent Publication (Kokai) No. 3-28351 discloses a PC steel rod with 400-9.
It is further disclosed in Japanese Patent Application Laid-Open No. 58-58 that the temperature is raised at a temperature of 00 ° C. or while being subjected to plastic working to increase the temperature by reverse transformation.
Japanese Patent No. 120738 describes that a wet linear machine is used for cooling during straightening.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、これら
に記載の方法は、いずれも歪を付与する工程を要し、生
産性の低下が懸念される。However, all of the methods described above require a step of imparting strain, and there is a concern that the productivity may be reduced.
【０００７】そこで本発明では、１０８０ＭＰａ以上の
高強度を有し、高温でのリラクセーション特性に優れた
ＰＣ鋼棒およびその製造条件を提供することを目的とす
る。Therefore, it is an object of the present invention to provide a PC steel rod having a high strength of 1080 MPa or more and excellent in relaxation characteristics at high temperatures, and manufacturing conditions thereof.
【０００８】[0008]
【課題を解決するための手段】本発明者等は、上記課題
を解決するため高温リラクセーション特性に及ぼす鋼の
組織、組成の影響について鋭意検討を行い、高炭素−Ｔ
ｉ，Ｍｏ系鋼をＰＣ鋼棒に成形後、焼入れ焼戻しを行い
焼戻しマルテンサイト組織中に微細析出物を析出させた
場合、優れた特性の得られることを見出した。In order to solve the above-mentioned problems, the inventors of the present invention have eagerly studied the influence of the structure and composition of steel on the high temperature relaxation characteristics, and have made a high carbon-T
It has been found that excellent characteristics can be obtained by forming a PC steel rod from i, Mo-based steel and then quenching and tempering to deposit fine precipitates in the tempered martensite structure.
【０００９】本発明は以上の知見を基に更に検討を加え
てなされたものであり、すなわち、本発明は、
１．焼戻しマルテンサイト単相組織を有し、焼戻しマル
テンサイト相中に粒径１０ｎｍ未満の微細析出物が分散
析出していることを特徴とする高温リラクセーション特
性に優れた高強度ＰＣ鋼棒。The present invention has been made through further studies based on the above findings, that is, the present invention is: A high-strength PC steel rod excellent in high-temperature relaxation characteristics, characterized by having a tempered martensite single-phase structure and having fine precipitates having a grain size of less than 10 nm dispersed and precipitated in the tempered martensite phase.
【００１０】２．質量％で、Ｃ≦０．７％、Ｓｉ≦３．
５％、Mn≦０．２〜３％、Al：０．０１〜０．１％、Ｔ
ｉ：０．０３〜０．２０％、Ｍｏ：０．０５〜０．６
％、残部Ｆｅ及び不可避的不純物よりなる１記載の高温
リラクセーションに優れた高強度ＰＣ鋼棒。2. % By mass, C ≦ 0.7%, Si ≦ 3.
5%, Mn ≦ 0.2-3%, Al: 0.01-0.1%, T
i: 0.03 to 0.20%, Mo: 0.05 to 0.6
%, The balance Fe and unavoidable impurities, which are excellent in high temperature relaxation as described in 1, and are high-strength PC steel rods.
【００１１】３．鋼組成として更に式（１）を満足する
ことを特徴とする２記載の高温リラクセーション特性に
優れた高強度ＰＣ鋼棒。
０．５≦（Ｃ／１２）／｛（Ｔｉ／４８）＋（Ｍｏ／９６）｝≦９．５（１）
但し、各元素は含有量（質量％）とする。3. A high-strength PC steel rod excellent in high-temperature relaxation characteristics as described in 2, wherein the steel composition further satisfies the formula (1). 0.5 ≦ (C / 12) / {(Ti / 48) + (Mo / 96)} ≦ 9.5 (1) However, the content of each element (mass%) is assumed.
【００１２】４．微細析出物がＴｉ，Ｍｏの炭化物であ
ることを特徴とする２または３の高温リラクセーション
特性に優れた高強度ＰＣ鋼棒。4. A high-strength PC steel rod excellent in high-temperature relaxation characteristics of 2 or 3, characterized in that the fine precipitates are carbides of Ti and Mo.
【００１３】５．鋼組成として、更に質量％で、Ｎｂ≦
０．０８％、Ｖ≦０．１５％、Ｗ≦１．５％の一種また
は二種以上を含有する２記載の高温リラクセーション特
性に優れた高強度ＰＣ鋼棒。5. Further, as a steel composition, in% by mass, Nb ≦
A high-strength PC steel rod excellent in high-temperature relaxation characteristics according to 2, containing one or more of 0.08%, V ≦ 0.15%, and W ≦ 1.5%.
【００１４】６．鋼組成として更に式（２）を満足する
ことを特徴とする５記載の高温リラクセーション特性に
優れた高強度ＰＣ鋼棒。
０．５≦（Ｃ／１２）／｛（Ｔｉ／４８）＋（Ｍｏ／９６）＋（Ｎｂ／９３）
＋（Ｖ／５１）＋（Ｗ／１８４）｝≦９．５ （２）
但し、各元素は含有量（質量％）で添加しないものは０
とする。6. A high-strength PC steel rod excellent in high-temperature relaxation characteristics according to 5, characterized in that the steel composition further satisfies the formula (2). 0.5 ≦ (C / 12) / {(Ti / 48) + (Mo / 96) + (Nb / 93) + (V / 51) + (W / 184)} ≦ 9.5 (2) Content of each element (% by mass) is 0 if not added
And
【００１５】７．微細析出物がＴｉとＭｏとＮｂ，Ｖ，
Ｗの内の少なくとも一種とを含む炭化物であることを特
徴とする５または６記載の高温リラクセーション特性に
優れた高強度ＰＣ鋼棒。7. Fine precipitates are Ti, Mo, Nb, V,
7. A high-strength PC steel rod excellent in high-temperature relaxation characteristics according to 5 or 6, which is a carbide containing at least one of W.
【００１６】８．鋼組成として更に質量％で、Ｃｕ：
０．２〜１．０％、Ｎｉ：０．２〜１．０％、Ｃｒ：
０．１〜１．０％、Ｂ：０．０００３〜０．００５％の
一種または二種以上を含有することを特徴とする１乃至
７のいずれか一つに記載の高温リラクセーション特性に
優れた高強度ＰＣ鋼棒。8. Further, as a steel composition, in mass%, Cu:
0.2-1.0%, Ni: 0.2-1.0%, Cr:
0.1 to 1.0% and B: 0.0003 to 0.005% of one kind or two or more kinds are contained, and the high temperature relaxation property is excellent as described in any one of 1 to 7. High strength PC steel rod.
【００１７】９．鋼組成が２、３、５，６、８のいずれ
か一つに記載の成分からなり、フェライト・パーライト
組織を有する棒鋼。9. A steel bar having a composition of any one of 2, 3, 5, 6, and 8 and having a ferrite-pearlite structure.
【００１８】１０．鋼組成が２、３、５，６、８のいず
れか一つに記載の鋼を１１００℃以上で加熱後、仕上げ
圧延温度８００℃以上で圧延し、その後の冷却におい
て、７００〜５５０℃を０．５℃／ｓｅｃ超えで冷却す
ることを特徴とする棒鋼の製造方法。10. After heating the steel described in any one of 2, 3, 5, 6, and 8 at 1100 ° C. or higher, it is rolled at a finish rolling temperature of 800 ° C. or higher and then cooled to 700 to 550 ° C. A method for manufacturing a steel bar, which comprises cooling at a rate of over 5 ° C / sec.
【００１９】１１．９記載の棒鋼をＰＣ鋼棒に成形後、
焼入れし、その後、５５０〜７００℃に１０分以上保持
する焼戻しをことを特徴とする高温リラクセーション特
性に優れた高強度ＰＣ鋼棒の製造方法。After forming the steel bar described in 11.9 into a PC steel bar,
A method for producing a high-strength PC steel rod having excellent high-temperature relaxation characteristics, which comprises quenching and then holding at 550 to 700 ° C. for 10 minutes or more.
【００２０】１２．鋼組成が２、３、５，６、８のいず
れか一つに記載の鋼を１１００℃以上に加熱後、仕上げ
圧延温度８００℃以上で圧延し、その後の冷却におい
て、７００〜５５０℃を０．５℃／ｓｅｃ超えで冷却し
て棒鋼とし、ＰＣ鋼棒に成形後、焼入れし、更にその後
５５０〜７００℃に１０分以上保持する焼戻しを行うこ
とを特徴とする高温リラクセーション特性に優れた高強
度ＰＣ鋼棒。12. After heating the steel described in any one of 2, 3, 5, 6, and 8 to 1100 ° C. or higher, the steel composition is rolled at a finish rolling temperature of 800 ° C. or higher, and then cooled to 700 to 550 ° C. Cooling at a rate of over 5 ° C / sec to form a steel bar, forming a PC steel bar, quenching, and then tempering by holding at 550 to 700 ° C for 10 minutes or more, which is excellent in high temperature relaxation characteristics. Strength PC steel rod.
【００２１】[0021]
【発明の実施の形態】本発明に係るＰＣ鋼棒のミクロ組
織、成分組成および製造条件について以下に詳細に説明
する。BEST MODE FOR CARRYING OUT THE INVENTION The microstructure, component composition and manufacturing conditions of the PC steel rod according to the present invention will be described in detail below.
【００２２】１．ミクロ組織
本発明に係るＰＣ鋼棒は、優れた高温リラクセーション
特性と１０８０ＭＰａ以上の高強度が得られるよう、そ
のミクロ組織を焼戻しマルテンサイト単相で且つ粒径１
０ｎｍ未満の微細析出物を含む組織に規定する。1. Microstructure The PC steel bar according to the present invention has a tempered martensite single phase and a grain size of 1 in order to obtain excellent high temperature relaxation characteristics and high strength of 1080 MPa or more.
It is defined as a structure containing fine precipitates of less than 0 nm.
【００２３】母相を焼戻しマルテンサイト単相組織とす
ることにより、強度及び靭性を向上させ、更に該組織中
に微細析出物を分散析出させることにより強度の向上と
ともに高温リラクセーション特性の向上が可能となる。Strength and toughness can be improved by making the matrix phase a tempered martensite single-phase structure, and further, by precipitating fine precipitates in the structure, it is possible to improve strength and high temperature relaxation characteristics. Become.
【００２４】また、本発明においてマルテンサイト単相
組織とは、断面組織観察（２００倍の光学顕微鏡組織観
察）でマルテンサイト面積率９５％以上とし、好ましく
は９８％以上とする。In the present invention, the martensite single-phase structure means a martensite area ratio of 95% or more, preferably 98% or more, by observing a cross-sectional structure (observation with a 200 × optical microscope structure).
【００２５】本発明では微細析出物は粒径１０ｎｍ未満
とする。析出物の粒径が１０ｎｍ以上の場合、強度およ
び高温リラクセーション特性の向上が得られにくい。In the present invention, the fine precipitates have a particle size of less than 10 nm. When the particle size of the precipitate is 10 nm or more, it is difficult to improve strength and high temperature relaxation characteristics.
【００２６】微細析出物の粒径は小さいほど有効で、望
ましくは５ｎｍ，更に望ましくは３ｎｍ以下で、そのよ
うな微細析出物としてＴｉ、Ｍｏを複合含有した炭化
物、またそれらに更にＮｂ，Ｖ，Ｗの一種または二種以
上を含む炭化物が好ましい。The smaller the particle size of the fine precipitates, the more effective it is, preferably 5 nm, more preferably 3 nm or less, and carbides containing Ti and Mo in combination as such fine precipitates, as well as Nb, V, and A carbide containing one kind or two or more kinds of W is preferable.
【００２７】これらの微細析出物の分布形態は特に規定
しないが、母相中に均一分散（分散析出）することが望
ましい。The distribution form of these fine precipitates is not particularly limited, but it is desirable that they are uniformly dispersed (dispersed and precipitated) in the mother phase.
【００２８】また、本発明において、微細析出物の大き
さは、全析出物の９０％以上で満足すれば、焼戻し後目
的とする引張強さが得られる。但し、１０ｎｍ以上の大
きさの析出物は析出物形成元素を消費し、強度に悪影響
をあたえるため、５０ｎｍ以下とすることが好ましい。In the present invention, if the size of the fine precipitates is 90% or more of the total precipitates, the desired tensile strength can be obtained after tempering. However, the precipitate having a size of 10 nm or more consumes the precipitate-forming element and adversely affects the strength.
【００２９】上述した析出物とは別に少量のＦｅ炭化物
を含有しても本発明の効果は損なわれないが、平均粒径
が１μｍ以上のＦｅ炭化物を多量に含むと靭性を阻害す
るため、本発明においては含有されるＦｅ炭化物の大き
さ上限は１μｍ、含有率は全体の１％以下とすることが
望ましい。The effect of the present invention is not impaired if a small amount of Fe carbide is contained in addition to the above-mentioned precipitates, but if a large amount of Fe carbide having an average particle size of 1 μm or more is contained, the toughness is impaired. In the present invention, the upper limit of the size of the Fe carbide contained is preferably 1 μm, and the content is preferably 1% or less of the whole.
【００３０】本発明における微細析出物の全析出物に占
める割合は、次の方法で決定できる。まず電子顕微鏡試
料を、ツインジェット法を用いた電解研磨法で作成し、
加速電圧２００ｋＶで観察する。The proportion of the fine precipitates in the present invention in all the precipitates can be determined by the following method. First, an electron microscope sample is prepared by an electrolytic polishing method using the twin jet method,
Observe at an acceleration voltage of 200 kV.
【００３１】その際、微細析出物が母相に対して計測可
能なコントラストになるように母相の結晶方位を制御
し、析出物の数え落としを最低限にするために焦点を正
焦点からずらしたデフォーカス法で観察を行う。At that time, the crystal orientation of the mother phase is controlled so that the fine precipitate has a contrast that can be measured with respect to the mother phase, and the focus is shifted from the normal focus in order to minimize counting of the precipitate. Observe by the defocus method.
【００３２】また、析出物粒子の計測を行った領域の試
料の厚さは電子エネルギー損失分光法を用いて、弾性散
乱ピークと非弾性散乱ピーク強度を測定することで評価
する。The thickness of the sample in the region where the precipitate particles are measured is evaluated by measuring the elastic scattering peak and inelastic scattering peak intensities using electron energy loss spectroscopy.
【００３３】この方法により、粒子数の計測と試料厚さ
の計測を同じ領域について実行することができる。粒子
数および粒子径の測定は試料の０．５×０．５μｍの領
域4箇所について行い、１μｍ2当たりに分布する析出物
を粒径ごとの個数として算出する。By this method, the measurement of the number of particles and the measurement of the sample thickness can be executed for the same region. The number of particles and the particle size are measured at four points in a region of 0.5 × 0.5 μm of the sample, and the precipitates distributed per 1 μm 2 are calculated as the number for each particle size.
【００３４】この値と試料厚さから、析出物の１μｍ3
当たりに分布する粒子径ごとの個数を算出し、径が１０
ｎｍ未満の析出物について、測定した全析出物に占める
割合を算出する。From this value and the sample thickness, 1 μm 3 of the precipitate
Calculate the number of each particle size distributed per hit,
For deposits with a size of less than nm, the ratio of the total deposits measured is calculated.
【００３５】２．成分組成
本発明鋼棒は上述したミクロ組織で目的とする性能が得
られるが、以下の成分組成とする。2. Ingredient Composition The steel rod of the present invention can achieve the desired performance with the above-described microstructure, but has the following ingredient composition.
【００３６】Ｃ
Ｃは強度確保のため添加する。０．７％を超えて含有す
ると微細析出物が粗大化し、強度が低下するため０．７
％以下とする。C C is added to secure the strength. If the content exceeds 0.7%, the fine precipitates become coarse and the strength decreases, so 0.7
% Or less.
【００３７】Ｓｉ
Ｓｉは高温リラクセーション特性向上のため添加する。
３．５％を超えるとその効果が飽和し、冷間加工時の変
形抵抗が高く、加工性が低下するため、３．５％以下と
する。Si Si is added to improve the high temperature relaxation characteristics.
If it exceeds 3.5%, the effect is saturated, the deformation resistance during cold working is high, and the workability is deteriorated, so the content is made 3.5% or less.
【００３８】Ｍｎ
熱間延性、焼入れ性を向上させるため、０．２〜３％を
添加する。Mn is added in an amount of 0.2 to 3% in order to improve hot ductility and hardenability.
【００３９】Ａｌ
脱酸剤として、及び高リラクセーション特性を向上させ
るため０．０１％以上添加する。一方、０．１％を超え
るとスポット溶接性が劣化するため０．１％以下とす
る。As an Al deoxidizer, 0.01% or more is added in order to improve high relaxation characteristics. On the other hand, if it exceeds 0.1%, the spot weldability deteriorates, so the content is made 0.1% or less.
【００４０】Ｔｉ
ＴｉはＴｉ系炭化物や、ＭｏとともにＴｉ−Ｍｏ系炭化
物を含む析出物を微細に析出させ、強度および高温リラ
クセーション特性を向上させるため添加する。０．０３
％未満では析出物量が少なく所望の強度及び高温リラク
セーション特性が得られないため０．０３％以上とし、
一方、０．２０％を超えて添加すると析出物が粗大化
し、冷間加工性が低下するため０．０３〜０．２０％と
する。Ti Ti is added in order to finely precipitate Ti-based carbides and precipitates containing Ti-Mo-based carbides together with Mo and to improve strength and high temperature relaxation characteristics. 0.03
%, The amount of precipitates is small and desired strength and high temperature relaxation characteristics cannot be obtained.
On the other hand, if added over 0.20%, the precipitates become coarse and the cold workability deteriorates, so the content is made 0.03 to 0.20%.
【００４１】Ｍｏ
ＭｏはＭｏ系炭化物や、ＴｉとともにＴｉ−Ｍｏ系炭化
物を含む析出物を微細に析出させ、強度及び高温リラク
セーション特性を向上させるため添加する。所望の引張
強度とし、高温リラクセーション特性を向上させるため
０．０５％以上とし、一方、０．６％を超えて添加する
と冷間鍛造性が低下するため０．０５〜０．６％とす
る。Mo Mo is added to finely precipitate Mo-based carbides and Ti-Mo-based carbides together with Ti and improve strength and high temperature relaxation characteristics. It has a desired tensile strength and is set to 0.05% or more in order to improve the high temperature relaxation characteristics. On the other hand, if it is added in excess of 0.6%, the cold forgeability is deteriorated, so the content is made 0.05 to 0.6%.
【００４２】Ｍｏは拡散速度が遅く、Ｔｉとともに析出
する場合、析出物の成長速度が低下し、微細な析出物が
得やすい。微細析出物におけるＴｉ，Ｍｏは原子比で
０．２≦Ｔｉ／Ｍｏ≦２．０、更に微細な場合は０．７
≦Ｔｉ／Ｍｏ≦１．５であることが観察された。Mo has a low diffusion rate, and when it precipitates together with Ti, the growth rate of the precipitate decreases, and it is easy to obtain a fine precipitate. The atomic ratio of Ti and Mo in the fine precipitates is 0.2 ≦ Ti / Mo ≦ 2.0, and 0.7 when finer.
It was observed that ≦ Ti / Mo ≦ 1.5.
【００４３】
（Ｃ／１２）／｛（Ｔｉ／４８）＋（Ｍｏ／９６）｝
本パラメータは、析出物の大きさに影響を与えるもの
で、０．５以上、９．５以下とした場合、粒径１０ｎｍ
未満の微細析出物の形成が容易となり好ましい。(C / 12) / {(Ti / 48) + (Mo / 96)} This parameter has an effect on the size of the precipitate, and is 0.5 or more and 9.5 or less. , Particle size 10 nm
It is preferable because the formation of fine precipitates of less than 1 is easy.
【００４４】更に、特性を向上させる場合、Ｎｂ，Ｖ，
Ｗの一種または二種以上を添加することが好ましい。In order to further improve the characteristics, Nb, V,
It is preferable to add one kind or two or more kinds of W.
【００４５】Ｎｂ
ＮｂはＴｉとともに微細析出物を形成して強度上昇に寄
与する。また組織を微細化し、結晶粒の整粒により延性
を向上させる。０．０８％を超えると過度に微細化し、
延性が低下するため０．０８％以下とする。Nb Nb forms fine precipitates together with Ti and contributes to strength increase. Further, the structure is made finer and the ductility is improved by sizing the crystal grains. If it exceeds 0.08%, it becomes too fine,
Since the ductility decreases, the content is made 0.08% or less.
【００４６】Ｖ
ＶはＴｉと微細析出物を形成するが、０．１５％を超え
ると析出物が粗大化するようになるため、０．１５％以
下とする。V V forms fine precipitates with Ti, but if it exceeds 0.15%, the precipitates become coarse, so the content is made 0.15% or less.
【００４７】Ｗ
ＷはＴｉと微細析出物を形成するが、１．５％を超える
と析出物が粗大化するようになるため、１．５％以下と
する。WW forms fine precipitates with Ti, but if it exceeds 1.5%, the precipitates become coarse, so the content is made 1.5% or less.
【００４８】これらの元素の添加においては、Ｃ，Ｔ
ｉ，Ｍｏ，Ｎｂ，Ｖ，Ｗの原子比を規定することが炭化
物の微細化に有効で（Ｃ／１２）／｛（Ｔｉ／４８）＋
（Ｍｏ／９６）＋（Ｎｂ／９３）＋（Ｖ／５１）＋（Ｗ
／１８４）｝を０．５以上、９．５以下とした場合、高
強度化に寄与する粒径１０ｎｍ未満の微細析出物の形成
が容易となる。In adding these elements, C, T
Prescribing the atomic ratio of i, Mo, Nb, V, W is effective for refining carbides (C / 12) / {(Ti / 48) +
(Mo / 96) + (Nb / 93) + (V / 51) + (W
/ 184)} is 0.5 or more and 9.5 or less, it becomes easy to form fine precipitates having a grain size of less than 10 nm, which contribute to strengthening.
【００４９】本発明で更に焼入れ性を向上させ所望の強
度とする場合、Ｃｕ，Ｎｉ，Ｃｒ，Ｂの一種または二種
以上を添加することができる。各元素の添加量はそのよ
うな効果が得られるようＣｕ：０．２〜１．０％、Ｎ
ｉ：０．２〜１．０％、Ｃｒ：０．１〜１．０％、Ｂ：
０．０００３〜０．００５％とする。When the hardenability is further improved in the present invention to obtain a desired strength, one or more of Cu, Ni, Cr and B can be added. The amount of each element added is Cu: 0.2 to 1.0%, N so as to obtain such an effect.
i: 0.2 to 1.0%, Cr: 0.1 to 1.0%, B:
It is set to 0.0003 to 0.005%.
【００５０】尚、これらの元素の含有量や添加の有無に
より本発明の効果が損なわれることはない。The effects of the present invention are not impaired depending on the contents of these elements and the presence or absence of addition thereof.
【００５１】３．製造条件
図１は本発明に係るＰＣ鋼棒の概略製造工程図でＳ１は
棒鋼製造工程、Ｓ２は搬送工程、Ｓ３は製品仕上げ過程
を示す。棒鋼製造工程（Ｓ１）で鋼塊を熱間圧延し棒鋼
とし品質検査後、出荷する。3. Manufacturing Conditions FIG. 1 is a schematic manufacturing process diagram of a PC steel bar according to the present invention, S1 is a steel bar manufacturing process, S2 is a carrying process, and S3 is a product finishing process. In the steel bar manufacturing step (S1), a steel ingot is hot-rolled into a steel bar, quality-inspected, and then shipped.
【００５２】製品仕上げ過程（Ｓ３）で、該棒鋼に冷間
引抜き、冷間曲げなどの冷間成形を行い、所望の形状と
した後、焼入れ焼戻しを施し、製品（ＰＣ鋼棒）とす
る。以下に望ましい製造工程について詳細に説明する。In the product finishing step (S3), the steel bar is subjected to cold forming such as cold drawing and cold bending to obtain a desired shape and then quenching and tempering to obtain a product (PC steel bar). The desirable manufacturing process will be described in detail below.
【００５３】圧延加熱温度
圧延加熱温度は１１００℃以上とする。本発明では、圧
延材（棒鋼）に微細析出物が析出して冷間加工性が劣化
することを抑制するために、熱間圧延時に溶解時から残
存する炭化物を固溶させる。Rolling heating temperature The rolling heating temperature is 1100 ° C. or higher. In the present invention, in order to suppress the deterioration of cold workability due to the precipitation of fine precipitates in the rolled material (steel bar), the carbides remaining after melting during hot rolling are solid-dissolved.
【００５４】圧延加熱温度を１１００℃未満とした場
合、溶解時から残存するＴｉ−Ｍｏ系炭化物等が固溶し
ないため１１００℃以上とする。When the rolling heating temperature is lower than 1100 ° C., the Ti—Mo type carbides and the like remaining after melting do not form a solid solution, so the temperature is set to 1100 ° C. or higher.
【００５５】圧延仕上げ温度
圧延仕上げ温度は８００℃未満では圧延荷重が高く真円
度が劣化するため８００℃以上とする。Rolling finish temperature If the rolling finish temperature is lower than 800 ° C, the rolling load is high and the roundness is deteriorated, so the rolling finish temperature is set to 800 ° C or higher.
【００５６】冷却速度
冷間加工前に微細析出物が析出して、冷間加工性を損な
わないよう、冷却速度を規定する。微細析出物の析出温
度範囲の７００〜５５０℃を、微細析出物の得られる限
界冷却速度（０．５℃／ｓｅｃ）超えで冷却する。本冷
却により圧延材（棒鋼）はフェライト＋パーライト組織
となる。Cooling rate The cooling rate is specified so that fine precipitates are not deposited before cold working and the cold workability is not impaired. The temperature of 700 to 550 [deg.] C., which is the deposition temperature range of the fine precipitate, is cooled at a cooling rate (0.5 [deg.] C./sec) at which the fine precipitate can be obtained. By this cooling, the rolled material (steel bar) becomes a ferrite + pearlite structure.
【００５７】焼入れ焼戻し
所望の形状に加工した後、微細析出物を析出させるよう
に、焼入れ後、加熱温度：５５０〜７００℃に１０分以
上保持する焼戻しを行う。５５０℃未満では、十分な量
の析出物が得られず、７００℃超えでは析出物が粗大化
するため、５５０〜７００℃とする。Quenching and tempering After processing into a desired shape, quenching is carried out by holding at a heating temperature of 550 to 700 ° C. for 10 minutes or more after quenching so as to deposit fine precipitates. If it is lower than 550 ° C, a sufficient amount of precipitates cannot be obtained, and if it exceeds 700 ° C, the precipitates become coarse, so the temperature is set to 550 to 700 ° C.
【００５８】本発明は請求項２、３、５，６、８のいず
れか一つに記載の組成を有する棒鋼を素材とし、上述し
た条件でＰＣ鋼棒を製造した場合、特に強度、高温リラ
クセーション特性に優れたものが得られる。The present invention uses a steel bar having the composition according to any one of claims 2, 3, 5, 6 and 8 as a raw material, and when a PC steel bar is manufactured under the above-mentioned conditions, particularly strength and high temperature relaxation A product with excellent characteristics can be obtained.
【００５９】[0059]
【実施例】表１に示す種々の組成の鋼（Ｎｏ．Ａ〜Ｈ）
を用い、強度、高温リラクセーション特性に及ぼす成分
組成の影響について調査した。各供試鋼の成分組成はＮ
ｏ．Ａ、Ｄは，請求項８、Ｎｏ．Ｂは請求項５、６、Ｎ
ｏ．Ｃは請求項２、３のそれぞれの発明範囲内で、Ｎ
ｏ．Ｅは請求項２記載の成分組成においてＣが発明範囲
外、Ｎｏ．Ｆ、Ｇは請求項３記載の成分組成においてＭ
ｎ、Ａｌのいずれかが発明範囲外となっている。Ｎｏ．
Ｈは請求項５記載の成分組成においてＴｉ，Ｍｏが発明
範囲外となっている。EXAMPLES Steels of various compositions shown in Table 1 (No. A to H)
Was used to investigate the effect of the component composition on the strength and high temperature relaxation characteristics. The composition of each test steel is N
o. A and D are claims 8, No. B is claim 5, 6, N
o. C is N within the scope of the invention of claims 2 and 3,
o. In the component composition according to claim 2, C is outside the scope of the invention, and No. E is No. F and G are M in the composition of claim 3.
Either n or Al is outside the scope of the invention. No.
In the component composition of H, Ti and Mo are outside the scope of the invention.
【００６０】供試鋼を１５０ｋｇ高周波小型溶解炉にて
溶製し、鋳造断面１６０×１６０ｍｍ鋼塊に鋳造後、２
４ｍｍ径の棒鋼に熱間圧延した、その後、２３ｍｍ径の
丸棒に引抜き、焼入れ焼戻しを行った。The test steel was melted in a high-frequency small-sized melting furnace of 150 kg, cast into a steel ingot with a cross section of 160 × 160 mm, and then 2
It was hot-rolled into a steel bar with a diameter of 4 mm, then drawn into a round bar with a diameter of 23 mm, and quenched and tempered.
【００６１】その後、リラクセーション試験、引張試
験、組織観察を行った。リラクセーション試験はＪＩＳ
Ｇ３１０９（３１３７）に準拠し、簡便な１０時間値を
用いて評価した。高温リラクセーションは４時間で１８
０℃に昇温し、３時間保持後、炉内冷却し荷重負荷から
２３時間後に測定した。Then, a relaxation test, a tensile test and a structure observation were conducted. The relaxation test is JIS
Evaluation was carried out in accordance with G3109 (3137) using a simple 10-hour value. High temperature relaxation is 18 in 4 hours
The temperature was raised to 0 ° C., held for 3 hours, cooled in the furnace, and measured 23 hours after the load was applied.
【００６２】引張試験はＪＩＳ４号の引張試験片を用
い、引張強さを求めた。組織観察は断面を光学顕微鏡で
観察するとともに、析出物を透過型電子顕微鏡（ＴＥ
Ｍ）で観察し、その組成をエネルギー分散型Ｘ線分光装
置（ＥＤＸ）により求めた。In the tensile test, a tensile test piece of JIS No. 4 was used to determine the tensile strength. In the structure observation, the cross section is observed with an optical microscope and the precipitate is examined with a transmission electron microscope (TE).
M), and the composition was determined by an energy dispersive X-ray spectrometer (EDX).
【００６３】表２に試験結果を示す。本発明例Ｎｏ．１
〜４は焼戻しマルテンサイト組織中に１０ｎｍ以下の微
細析出物が観察され、１０８０ＭＰａ以上の高強度でか
つ優れた高温リラクセーション特性（７％以下）が得ら
れた。Table 2 shows the test results. Inventive Example No. 1
In Nos. 4 to 4, fine precipitates of 10 nm or less were observed in the tempered martensite structure, and high strength of 1080 MPa or more and excellent high temperature relaxation characteristics (7% or less) were obtained.
【００６４】一方、Ｎｏ．５は鋼組成は請求項３記載の
本発明範囲内であるが、冷間加工後の焼戻し温度が本発
明範囲外で高く、析出物が１５０ｎｍと粗大化し、引張
強さ、高温リラクセーション特性に劣る。On the other hand, No. No. 5 has a steel composition within the scope of the present invention as set forth in claim 3, but the tempering temperature after cold working is high outside the scope of the present invention, precipitates are coarsened to 150 nm, and tensile strength and high temperature relaxation characteristics are poor. .
【００６５】Ｎｏ．６はＣ量が、Ｎｏ．９はＴｉ、Ｍｏ
量が夫々本発明範囲外であり、引張強さ、高温リラクセ
ーション特性の両者が劣っている。No. No. 6 has a C content of No. 6 9 is Ti, Mo
The amounts are out of the range of the present invention, and both the tensile strength and the high temperature relaxation property are inferior.
【００６６】Ｎｏ．７はＭｎ量が低いため引張強度が低
く、Ｎｏ．８はＡｌ量が低いため高温リラクセーション
特性に劣る。No. No. 7 has a low Mn content and thus has a low tensile strength. No. 8 is inferior in high temperature relaxation characteristics because of low Al content.
【００６７】[0067]
【表１】 [Table 1]
【００６８】[0068]
【表２】 [Table 2]
【００６９】[0069]
【発明の効果】本発明によれば、高温リラクセーション
特性に優れ且つ高強度なＰＣ鋼棒およびその製造方法が
得られ、産業上極めて有用である。Industrial Applicability According to the present invention, a PC steel rod excellent in high temperature relaxation characteristics and high in strength and a method for producing the same can be obtained, which is extremely useful in industry.
【図１】 本発明ＰＣ鋼棒の製造工程の一例を示す図。FIG. 1 is a diagram showing an example of a manufacturing process of a PC steel rod of the present invention.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 白神 哲夫 東京都中央区新川２丁目12番８号 エヌケ ーケー条鋼株式会社内 (72)発明者 冨田 邦和 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 船川 義正 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 塩崎 毅 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 Ｆターム(参考） 4K032 AA01 AA02 AA04 AA05 AA06 AA11 AA14 AA16 AA17 AA19 AA22 AA23 AA31 AA32 AA35 AA36 AA37 BA02 CA01 CA02 CA03 CB02 CC03 CC04 CD01 CD02 CD03 CF01 CF02 CF03 4K042 AA14 BA14 CA02 CA05 CA06 CA08 CA10 CA12 DA01 DA02 DE05 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Tetsuo Shirakami Enuke, 2-12-8 Shinkawa, Chuo-ku, Tokyo -K-Koji Co., Ltd. (72) Inventor Kunikazu Tomita 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd. (72) Inventor Yoshimasa Funakawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd. (72) Inventor Takeshi Shiozaki 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Main Steel Pipe Co., Ltd. F-term (reference) 4K032 AA01 AA02 AA04 AA05 AA06 AA11 AA14 AA16 AA17 AA19 AA22 AA23 AA31 AA32 AA35 AA36 AA37 BA02 CA01 CA02 CA03 CB02 CC03 CC04 CD01 CD02 CD03 CF01 CF02 CF03 4K042 AA14 BA14 CA02 CA05 CA06 CA08 CA10 CA12 DA01 DA02 DE05
Claims (12)
焼戻しマルテンサイト相中に粒径１０ｎｍ未満の微細析
出物が分散析出していることを特徴とする高温リラクセ
ーション特性に優れた高強度ＰＣ鋼棒。1. A tempered martensite single-phase structure,
A high-strength PC steel rod excellent in high-temperature relaxation characteristics, characterized in that fine precipitates having a particle size of less than 10 nm are dispersed and precipitated in a tempered martensite phase.
％、Mn≦０．２〜３％、Ａｌ：０．０１〜０．１％、Ｔ
ｉ：０．０３〜０．２０％、Ｍｏ：０．０５〜０．６
％、残部Ｆｅ及び不可避的不純物よりなる請求項１記載
の高温リラクセーションに優れた高強度ＰＣ鋼棒。2. In mass%, C ≦ 0.7%, Si ≦ 3.5.
%, Mn ≦ 0.2 to 3%, Al: 0.01 to 0.1%, T
i: 0.03 to 0.20%, Mo: 0.05 to 0.6
%, The balance Fe and unavoidable impurities. The high-strength PC steel rod excellent in high-temperature relaxation according to claim 1.
とを特徴とする請求項２記載の高温リラクセーション特
性に優れた高強度ＰＣ鋼棒。 ０．５≦（Ｃ／１２）／｛（Ｔｉ／４８）＋（Ｍｏ／９６）｝≦９．５ （１） 但し、各元素は含有量（質量％）とする。3. The high-strength PC steel rod excellent in high-temperature relaxation characteristics according to claim 2, wherein the steel composition further satisfies the formula (1). 0.5 ≦ (C / 12) / {(Ti / 48) + (Mo / 96)} ≦ 9.5 (1) However, each element is a content (mass%).
ことを特徴とする請求項２または３の高温リラクセーシ
ョン特性に優れた高強度ＰＣ鋼棒。4. The high-strength PC steel rod excellent in high-temperature relaxation characteristics according to claim 2 or 3, wherein the fine precipitates are carbides of Ti and Mo.
０．０８％、Ｖ≦０．１５％、Ｗ≦１．５％の一種また
は二種以上を含有する請求項２記載の高温リラクセーシ
ョン特性に優れた高強度ＰＣ鋼棒。5. The steel composition, further in mass%, Nb ≦
The high-strength PC steel rod excellent in high-temperature relaxation characteristics according to claim 2, containing one or more of 0.08%, V≤0.15%, and W≤1.5%.
とを特徴とする請求項５記載の高温リラクセーション特
性に優れた高強度ＰＣ鋼棒。 ０．５≦（Ｃ／１２）／｛（Ｔｉ／４８）＋（Ｍｏ／９６）＋（Ｎｂ／９３） ＋（Ｖ／５１）＋（Ｗ／１８４）｝≦９．５ （２） 但し、各元素は含有量（質量％）で添加しないものは０
とする。6. The high-strength PC steel rod excellent in high-temperature relaxation characteristics according to claim 5, wherein the steel composition further satisfies the formula (2). 0.5 ≦ (C / 12) / {(Ti / 48) + (Mo / 96) + (Nb / 93) + (V / 51) + (W / 184)} ≦ 9.5 (2) Content of each element (% by mass) is 0 if not added
And
の内の少なくとも一種とを含む炭化物であることを特徴
とする請求項５または６記載の高温リラクセーション特
性に優れた高強度ＰＣ鋼棒。7. The fine precipitates are Ti, Mo, Nb, V and W.
A high-strength PC steel rod excellent in high-temperature relaxation characteristics according to claim 5, which is a carbide containing at least one of the above.
２〜１．０％、Ｎｉ：０．２〜１．０％、Ｃｒ：０．１
〜１．０％、Ｂ：０．０００３〜０．００５％の一種ま
たは二種以上を含有することを特徴とする請求項１乃至
７のいずれか一つに記載の高温リラクセーション特性に
優れた高強度ＰＣ鋼棒。8. A steel composition further comprising mass% Cu: 0.
2 to 1.0%, Ni: 0.2 to 1.0%, Cr: 0.1
To 1.0%, B: 0.0003 to 0.005%, or a combination of two or more thereof, which is excellent in high temperature relaxation characteristics according to any one of claims 1 to 7. Strength PC steel rod.
ずれか一つに記載の成分からなり、フェライト・パーラ
イト組織を有する棒鋼。9. A steel bar having a steel composition consisting of the composition according to any one of claims 2, 3, 5, 6, and 8 and having a ferrite-pearlite structure.
いずれか一つに記載の鋼を１１００℃以上で加熱後、仕
上げ圧延温度８００℃以上で圧延し、その後の冷却にお
いて、７００〜５５０℃を０．５℃／ｓｅｃ超えで冷却
することを特徴とする棒鋼の製造方法。10. The steel composition according to claim 2, wherein the steel according to any one of claims 2, 3, 5, 6, and 8 is heated at 1100 ° C. or higher, then rolled at a finish rolling temperature of 800 ° C. or higher, and then cooled. , 700 to 550 ° C. at 0.5 ° C./sec or higher, a method for manufacturing a steel bar.
後、焼入れし、その後、５５０〜７００℃に１０分以上
保持する焼戻しを行うことを特徴とする高温リラクセー
ション特性に優れた高強度ＰＣ鋼棒の製造方法。11. A high-strength steel sheet having excellent high-temperature relaxation characteristics, characterized in that after the steel bar according to claim 9 is formed into a PC steel bar, it is quenched and then tempered by holding it at 550 to 700 ° C. for 10 minutes or more. Method for manufacturing PC steel rod.
いずれか一つに記載の鋼を１１００℃以上に加熱後、仕
上げ圧延温度８００℃以上で圧延し、その後の冷却にお
いて、７００〜５５０℃を０．５℃／ｓｅｃ超えで冷却
して棒鋼とし、ＰＣ鋼棒に成形後、焼入れし、更にその
後５５０〜７００℃に１０分以上保持する焼戻しを行う
ことを特徴とする高温リラクセーション特性に優れた高
強度ＰＣ鋼棒。12. The steel composition according to claim 2, wherein the steel according to any one of claims 2, 3, 5, 6 and 8 is heated to 1100 ° C. or higher, and then rolled at a finish rolling temperature of 800 ° C. or higher, and then cooled. , 700 to 550 ° C. at a rate of more than 0.5 ° C./sec to form a steel bar, which is formed into a PC steel bar, quenched, and then tempered at 550 to 700 ° C. for 10 minutes or more. High-strength PC steel rod with excellent high-temperature relaxation characteristics.
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|---|---|---|---|
| JP2002125404A JP4121300B2 (en) | 2002-04-26 | 2002-04-26 | High strength PC steel bar excellent in high temperature relaxation characteristics and method for producing the same |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2002125404A JP4121300B2 (en) | 2002-04-26 | 2002-04-26 | High strength PC steel bar excellent in high temperature relaxation characteristics and method for producing the same |
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|---|---|
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| JP4121300B2 JP4121300B2 (en) | 2008-07-23 |
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|---|---|---|---|
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| CN103589847A (en) * | 2013-11-20 | 2014-02-19 | 大连赛瑞金属制品有限公司 | Production technique of suspension insulator ultralow temperature steel pins |
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| CN115927958A (en) * | 2022-11-12 | 2023-04-07 | 南阳汉冶特钢有限公司 | Production method of high-strength construction steel Q420GJDZ35 |
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| CN104975158A (en) * | 2015-07-08 | 2015-10-14 | 江苏宇山盛佳特钢制品有限公司 | Partition independent control continuous long steel rod heat treatment furnace and process thereof |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103589847A (en) * | 2013-11-20 | 2014-02-19 | 大连赛瑞金属制品有限公司 | Production technique of suspension insulator ultralow temperature steel pins |
| CN104805380A (en) * | 2015-05-06 | 2015-07-29 | 山东钢铁股份有限公司 | Low-temper-brittleness Cr-Mo steel plate for high temperature resisting pressure-bearing equipment and preparation method of steel plate |
| CN114107788A (en) * | 2020-08-31 | 2022-03-01 | 宝山钢铁股份有限公司 | 980 MPa-grade tempered martensite type high-reaming steel and manufacturing method thereof |
| CN115927958A (en) * | 2022-11-12 | 2023-04-07 | 南阳汉冶特钢有限公司 | Production method of high-strength construction steel Q420GJDZ35 |
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|---|---|
| JP4121300B2 (en) | 2008-07-23 |
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