JP2007113079A - Deformed stainless steel bar having excellent durability in concrete structure - Google Patents
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- 239000004567 concrete Substances 0.000 title claims abstract description 41
- 229910001220 stainless steel Inorganic materials 0.000 title abstract description 13
- 239000010935 stainless steel Substances 0.000 title abstract description 12
- 229910000831 Steel Inorganic materials 0.000 claims description 50
- 239000010959 steel Substances 0.000 claims description 50
- 230000007797 corrosion Effects 0.000 abstract description 30
- 238000005260 corrosion Methods 0.000 abstract description 30
- 229910052804 chromium Inorganic materials 0.000 abstract description 5
- 239000000203 mixture Substances 0.000 abstract description 5
- 150000003839 salts Chemical class 0.000 abstract description 4
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 229910052748 manganese Inorganic materials 0.000 abstract description 2
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 2
- 229910052717 sulfur Inorganic materials 0.000 abstract description 2
- 239000000853 adhesive Substances 0.000 abstract 1
- 230000001070 adhesive effect Effects 0.000 abstract 1
- 239000012779 reinforcing material Substances 0.000 abstract 1
- 239000011651 chromium Substances 0.000 description 25
- 230000003014 reinforcing effect Effects 0.000 description 23
- 230000000694 effects Effects 0.000 description 10
- 229910045601 alloy Inorganic materials 0.000 description 8
- 239000000956 alloy Substances 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 8
- 238000005098 hot rolling Methods 0.000 description 7
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 238000005452 bending Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 3
- 229910000734 martensite Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 230000002411 adverse Effects 0.000 description 2
- 238000000137 annealing Methods 0.000 description 2
- 238000005422 blasting Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000003822 epoxy resin Substances 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 150000001247 metal acetylides Chemical class 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 229920000647 polyepoxide Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000037303 wrinkles Effects 0.000 description 2
- 239000011701 zinc Substances 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- XWROUVVQGRRRMF-UHFFFAOYSA-N F.O[N+]([O-])=O Chemical compound F.O[N+]([O-])=O XWROUVVQGRRRMF-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000011398 Portland cement Substances 0.000 description 1
- 241000221535 Pucciniales Species 0.000 description 1
- 229910001294 Reinforcing steel Inorganic materials 0.000 description 1
- 229910000589 SAE 304 stainless steel Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 229910001039 duplex stainless steel Inorganic materials 0.000 description 1
- 238000007730 finishing process Methods 0.000 description 1
- 238000005242 forging Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 231100000989 no adverse effect Toxicity 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000011150 reinforced concrete Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
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Abstract
Description
本発明は、コンクリート構造物中における耐久性に優れたステンレス異形棒鋼(以下、鉄筋ともいう)に関する。 The present invention relates to a deformed stainless steel bar (hereinafter also referred to as a reinforcing bar) having excellent durability in a concrete structure.
従来、鉄筋用鋼としては295SD295鋼、345SD345鋼、390SD390鋼などの普通鋼が用いられてきたが、このような普通鋼鉄筋は、コンクリート中に塩化物イオンが何らかの原因で侵入した場合や、コンクリートが中性化した場合には容易に発錆する。錆が発生すると錆は体積膨張するためコンクリートにひびが入り崩落することや、鉄筋自身が減肉して強度が保てなくなるためコンクリート構造物の耐久性を大きく損なうことになる。 Conventionally, ordinary steels such as 295SD295 steel, 345SD345 steel, and 390SD390 steel have been used as the steel for reinforcing bars. Rust easily rusts when it becomes neutral. When rust is generated, the volume of the rust expands and cracks in the concrete and collapses, and the strength of the concrete structure is greatly impaired because the reinforcing bars themselves are thinned and cannot maintain strength.
その対策として、次に述べるような種々の防食鉄筋が提案されている。
例えば、特開昭62−1888754号公報には、0.30〜5.00質量%のCrと0.50超〜1.50質量%のCuを複合添加すると共に、Ni、 Mo、 Vを併せて添加することによって、耐食性と曲げ加工性を向上させた鉄筋が開示されている。
As countermeasures, various anticorrosion reinforcing bars as described below have been proposed.
For example, in Japanese Patent Laid-Open No. 62-1888754, 0.30 to 5.00% by mass of Cr and more than 0.50 to 1.50% by mass of Cu are added together, and Ni, Mo, and V are combined. By adding these, reinforcing bars having improved corrosion resistance and bending workability are disclosed.
しかしながら、特開昭62−188754号公報のように、Cr含有量が5質量%以下の場合には、海岸や融雪塩を多量に散布するいわゆる塩害地域等では十分な耐食性を得ることができないという問題があった。 However, as disclosed in Japanese Patent Application Laid-Open No. 62-188754, when the Cr content is 5% by mass or less, sufficient corrosion resistance cannot be obtained in a coastal area or a so-called salt damage area where a large amount of snow melting salt is sprayed. There was a problem.
現在、塩化物イオンに対し耐食性を有す鉄筋としては、エポキシ樹脂被覆鉄筋と亜鉛めっき鉄筋がある。エポキシ樹脂被覆鉄筋は、塗膜によって鉄筋を保護するものであるが、運搬や施工時において塗膜に疵が付きやすく、施工時に生じた疵や溶接により脱膜した部分については現地で補修しなければならない。また曲げ加工の際に、疵を生じない特殊な加工機が必要となることや曲げ加工により疵が発生した場合は、樹脂を再被覆するなど多大な労力を要す。また、塗膜表面は節やリブにおいても素材表面に比べて滑らかであるため、コンクリートとの付着強度には限界があった。 At present, as reinforcing bars having corrosion resistance to chloride ions, there are epoxy resin-coated reinforcing bars and galvanized reinforcing bars. Epoxy resin-coated reinforcing bars protect the reinforcing bars with a paint film, but the paint film tends to be wrinkled during transportation and construction. I must. Further, when bending is performed, a special processing machine that does not generate wrinkles is required, and when wrinkles are generated by bending, great effort is required such as re-coating with resin. Moreover, since the coating surface is smoother than the surface of the material even at the nodes and ribs, there is a limit to the adhesion strength with concrete.
また亜鉛めっき鉄筋は、亜鉛の犠牲防食作用で下地の鉄筋の発錆を抑制するものであるが、下地の発錆までの時間が亜鉛の目付け量に依存するため 恒久的な防食性能は期待できない。また、亜鉛めっきの腐食生成物がコンクリート構造物の耐久性にどのような影響を与えるか不明な点も多かった。 In addition, galvanized reinforcing bars suppress the rusting of the underlying reinforcing bars due to the sacrificial anticorrosive action of zinc, but since the time until the underlying rusting depends on the basis weight of zinc, permanent anticorrosive performance cannot be expected. . In addition, there are many unclear points on how the corrosion products of galvanization affect the durability of concrete structures.
海外では、塩害地域用防食鉄筋としてステンレス鉄筋が部分的に使用されている。しかしながら、それらは殆ど SUS 304鋼やSUS 316鋼さらには二相ステンレス鋼といった高価なステンレス鋼であり、これらは耐食性には極めて優れているものの、高価であるため使用範囲が限定されるという問題があった。 Overseas, stainless steel rebars are partially used as anticorrosion rebars for salt damage areas. However, they are mostly expensive stainless steels such as SUS 304 steel, SUS 316 steel and even duplex stainless steel, and these are extremely excellent in corrosion resistance, but are expensive and have a problem that the range of use is limited. there were.
特開平4−267199号公報には質量%でC0.1%以下、Cr12〜14%、Si2.0%以下、Ni0.5%以下、Mn0.75%以下、N0.1%以下、P0.04%以下、Al0.1%以下、S0.03%以下、C+Nが0.04%以上0.10%以下、次式で表されるNi−balが−5<Ni−bal<−3.5 (式;Ni−bal=30(C+N)+0.5Mn+Ni+8.2−1.1(1.5Si+Cr))を満足し、残部不可避不純物およびFeよりなる鋼を1300〜1100℃に加熱し、1000℃以下で熱間圧延を終了するように圧延したのち、放冷を行うことよりなる、降伏強さ35.0kg/mm2以上、伸び15%以上の安価なクロムステンレス棒鋼を製造する方法が開示されている。
このようなCr量のステンレス棒鋼は安価でしかも優れた耐食性を有している。鉄筋の性能としては、素材自身の耐食性に加えて、コンクリートとの高い付着強度を有することが重要であるが、特開平4−267199号公報には付着強度に関しては検討されていなかった。
Japanese Patent Application Laid-Open No. 4-267199 discloses mass% of C 0.1% or less, Cr 12-14%, Si 2.0% or less, Ni 0.5% or less, Mn 0.75% or less, N 0.1% or less, P 0.04. % Or less, Al 0.1% or less, S 0.03% or less, C + N is 0.04% or more and 0.10% or less, and Ni-bal represented by the following formula is −5 <Ni-bal <−3.5 ( Ni-bal = 30 (C + N) + 0.5Mn + Ni + 8.2-1.1 (1.5Si + Cr)), and the steel consisting of the remaining inevitable impurities and Fe is heated to 1300-1100 ° C. A method of producing an inexpensive chromium stainless steel bar having a yield strength of 35.0 kg / mm 2 or more and an elongation of 15% or more, which is formed by rolling after completion of hot rolling and allowing to cool, is disclosed.
Such stainless steel bars with a Cr content are inexpensive and have excellent corrosion resistance. As for the performance of the reinforcing bars, in addition to the corrosion resistance of the material itself, it is important to have high adhesion strength with concrete, but JP-A-4-267199 has not studied the adhesion strength.
また、特開2002−212682号公報にはCr量が 5.0質量%超で、かつ少量のCoを含有する鉄筋用Cr含有棒鋼が開示されている。しかしながらこの特開2002−212682号公報にも、付着強度に関しては検討されていなかった。
本発明は、上記の問題点を解消するためになされたものであり、鉄筋腐食に起因したコンクリート構造物の崩落を防止し、エポキシ被覆鉄筋のように施工の際の厳しい制約がなく、亜鉛めっき鉄筋のように防食期間に限りがなく、しかも海外で使用されている ステンレス鉄筋よりもはるかに安価で、付着強度が高く、鉄筋として優れた特性を有するステンレス異形棒鋼を提供することを課題とする。 The present invention has been made to solve the above-described problems, prevents collapse of concrete structures due to corrosion of reinforcing bars, and has no strict restrictions during construction like epoxy-coated reinforcing bars, and is galvanized. It is an object to provide a stainless steel deformed steel bar that has a limited anticorrosion period like a rebar, is much cheaper than a stainless steel rebar used overseas, has high adhesion strength, and has excellent properties as a rebar. .
そこで、発明者らは、上記の課題を解決すべく、異形棒鋼としての機械的性質及び耐食性や強度に及ぼす合金元素の影響、コンクリート付着強度に及ぼす節とリブの形状の影響について調査を行った。その結果、Cr量が 10.5〜13.5質量%のステンレス鋼で、鉄筋の節を特定形状とすることにより、耐食性と強度及びコンクリートとの付着強度を向上させ、しかも経済性にも優れていることの知見を得た。本発明は、本知見に立脚するものである。 In order to solve the above problems, the inventors investigated the influence of alloy elements on the mechanical properties and corrosion resistance and strength of deformed steel bars, and the influence of the shape of the nodes and ribs on the concrete bond strength. . As a result, stainless steel with a Cr content of 10.5 to 13.5% by mass and a reinforcing bar with a specific shape can improve corrosion resistance, strength and bond strength with concrete, and is also economical. I got the knowledge that The present invention is based on this finding.
すなわち、本発明の要旨構成は次のとおりである。
(1)質量%で、
C :0.15%以下、
Si:2.0%以下、
Mn:2.0%以下、
P:0.04%以下、
S:0.03%以下、
Cr:10.50〜13.50%を含み、
表面の軸線方向に設けられたリブと、該リブと交差する節とを有しており、
少なくとも一つの節が前記リブに対し30度〜85度または95度〜150度の角度で交わり、該節の高さが公称直径の4.0%以上10.0%以下で、前記リブに対し同方向の節と節の間隔が公称直径の0.5倍以上2.0倍以内であることを特徴とする、コンクリート構造物中における耐久性に優れたステンレス異形棒鋼。
That is, the gist configuration of the present invention is as follows.
(1) In mass%,
C: 0.15% or less,
Si: 2.0% or less,
Mn: 2.0% or less,
P: 0.04% or less,
S: 0.03% or less,
Cr: 10.50 to 13.50% included,
A rib provided in the axial direction of the surface, and a node intersecting with the rib;
At least one node intersects the rib at an angle of 30 to 85 degrees or 95 to 150 degrees, and the height of the node is not less than 4.0% and not more than 10.0% of the nominal diameter; Stainless deformed steel bar with excellent durability in concrete structures, characterized in that the distance between nodes in the same direction is 0.5 times or more and 2.0 times the nominal diameter.
(2)質量%で、
C :0.15%以下、
Si:2.0%以下、
Mn:2.0%以下、
P:0.04%以下、
S:0.03%以下、
Cr:10.50〜13.50%を含み、
0.2%耐力が295MPa以上を有し、
表面の軸線方向に設けられたリブと、該リブと交差する節とを有しており、
少なくとも一つの節が前記リブに対し30度〜85度または95度〜150度の角度で交わり、該節の高さが公称直径の4.0%以上10.0%以下で、前記リブに対し同方向の節と節の間隔が公称直径の0.5倍以上2.0倍以内であることを特徴とする、コンクリート構造物中における耐久性に優れたステンレス異形棒鋼。
(2) In mass%,
C: 0.15% or less,
Si: 2.0% or less,
Mn: 2.0% or less,
P: 0.04% or less,
S: 0.03% or less,
Cr: 10.50 to 13.50% included,
0.2% proof stress is 295 MPa or more,
A rib provided in the axial direction of the surface, and a node intersecting with the rib;
At least one node intersects the rib at an angle of 30 to 85 degrees or 95 to 150 degrees, and the height of the node is not less than 4.0% and not more than 10.0% of the nominal diameter; Stainless deformed steel bar with excellent durability in concrete structures, characterized in that the distance between nodes in the same direction is 0.5 times or more and 2.0 times the nominal diameter.
(3)さらに、質量%で、
Ni:0.6%以下、
N::0.1%以下、
γp= 700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2≧0で、
0.2%耐力が295MPa以上であることを特徴とする、(1)または(2)に記載のコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。
(3) Furthermore, in mass%,
Ni: 0.6% or less,
N :: 0.1% or less,
γ p = 700 × (C) + 20 × (Ni) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
−37 × (Al) + 63.2 ≧ 0,
The stainless deformed steel bar having excellent durability in a concrete structure according to (1) or (2), wherein the 0.2% proof stress is 295 MPa or more.
(4) さらに、質量%で、
Ni:0.6%以下、
N::0.1%以下、
γp= 700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2≧10で、
0.2%耐力が345MPa以上であることを特徴とする、(1)または(2)に記載のコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。
(4) Furthermore, in mass%,
Ni: 0.6% or less,
N :: 0.1% or less,
γ p = 700 × (C) + 20 × (Ni) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
−37 × (Al) + 63.2 ≧ 10,
A stainless deformed steel bar excellent in durability in a concrete structure according to (1) or (2), wherein the 0.2% proof stress is 345 MPa or more.
(5)さらに、質量%で、
Ni:0.66%以下、
N::0.1%以下、
γp= 700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2≧15で、
0.2%耐力が390MPa以上であることを特徴とする、(1)または(2)に記載のコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。
(5) Furthermore, in mass%,
Ni: 0.66% or less,
N :: 0.1% or less,
γ p = 700 × (C) + 20 × (Ni) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
−37 × (Al) + 63.2 ≧ 15,
A stainless deformed steel bar excellent in durability in a concrete structure according to (1) or (2), wherein the 0.2% proof stress is 390 MPa or more.
(6)(1)乃至(5)のいずれかに記載のステンレス異形棒鋼において、外表面が脱スケールされていることを特徴とするコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。 (6) The stainless deformed steel bar according to any one of (1) to (5), wherein the outer surface is descaled and has excellent durability in a concrete structure.
以上より、本発明によれば、付着強度が高く、発錆し難い異形棒鋼を得ることができ、コンクリート構造物において高い付着強度を長期間維持することが可能であるため、コンクリート構造物の耐久性を格段に向上させることができるなど、産業上有用な著しい効果を奏する。 As described above, according to the present invention, it is possible to obtain a deformed steel bar having high adhesion strength and hardly rusting, and it is possible to maintain high adhesion strength for a long time in a concrete structure. It has significant industrially useful effects, such as significantly improved performance.
以下、本発明について具体的に説明する。まず、本発明において、鋼材の成 分組成を上記の範囲に限定した理由について説明する。
(C: 0.15 質量%以下)
Cは、オーステナイト相および炭化物の生成元素である。オーステナイト相は、熱間加工後においてマルテンサイト組織を生じて強度を向上させ、また微細炭化物も強度の向上に寄与する。しかしながら、 0.15質量%超では硬くなり過ぎて靱性が劣化する。従って、C量は 0.15 質量%以下の範囲に限定した。溶接部の靭性を確保するためには、C量は0.03 質量%以下の範囲にすることが望ましい。
また、0.001質量%未満ではオーステナイト相や微細炭化物の生成量が少なすぎて強度が不足するため、0.001%以上含有することが望ましい。
Hereinafter, the present invention will be specifically described. First, the reason why the composition of the steel material is limited to the above range in the present invention will be described.
(C: 0.15 mass% or less)
C is an austenite phase and carbide forming element. The austenite phase produces a martensite structure after hot working to improve strength, and fine carbides also contribute to strength improvement. However, if it exceeds 0.15% by mass, it becomes too hard and the toughness deteriorates. Therefore, the C content is limited to a range of 0.15% by mass or less. In order to ensure the toughness of the welded portion, it is desirable that the C content be in the range of 0.03 mass% or less.
Further, if it is less than 0.001% by mass, the amount of austenite phase and fine carbides produced is too small and the strength is insufficient, so 0.001% or more is desirable.
(Si:2.0%以下)
Siは、脱酸剤として有用な元素であるが、含有量が 2.0質量%超になると硬くなり機械的性質が劣化する。従って、Si量は 2.0 質量%以下とした。
また、0.1%未満では脱酸効果が得られないため0.1%以上含有することが望ましい。
(Si: 2.0% or less)
Si is an element useful as a deoxidizer, but when the content exceeds 2.0% by mass, it becomes hard and its mechanical properties deteriorate. Therefore, the Si content is set to 2.0% by mass or less.
Further, if it is less than 0.1%, the deoxidation effect cannot be obtained, so it is desirable to contain 0.1% or more.
(Mn:2.0%以下)
Mnも、Cと同様、オーステナイト相生成元素であるが、Mn含有量が 2.0質量%超になると鋼中に残存する介在物が多くなり耐食性が劣化する。従って、Mn量は2.0 質量%以下の範囲とした。
また、含有量が0.1質量%より少ないとオーステナイト相の生成が不十分となるため、熱間加工後のマルテンサイト組織が少なくなって、強度不足となる。したがって0.1%以上含有することが望ましい。
(Mn: 2.0% or less)
Mn is also an austenite phase-forming element like C, but if the Mn content exceeds 2.0 mass%, the inclusions remaining in the steel increase and the corrosion resistance deteriorates. Therefore, the amount of Mn is set to a range of 2.0% by mass or less.
On the other hand, if the content is less than 0.1% by mass, the austenite phase is not sufficiently generated, so that the martensite structure after hot working is reduced, resulting in insufficient strength. Therefore, it is desirable to contain 0.1% or more.
(P:0.04%以下)
Pは、靱性等の機械的性質を劣化させるだけでなく、耐食性に対しても有害な元素であり、特にP含有量が0.04質量%超になるとその悪影響が顕著になるので、P量は0.04質量%以下とした。
(P: 0.04% or less)
P is an element that not only deteriorates mechanical properties such as toughness but is also harmful to corrosion resistance. Particularly, when the P content exceeds 0.04% by mass, its adverse effect becomes significant. Was 0.04 mass% or less.
(S:0.03%以下)
Sは、Mnと結合してMnSを形成し、初期発銹起点となる。またSは、結晶粒界に偏析して、粒界脆化を促進する有害元素でもあるので、極力低減することが好ましい。特にS含有量が0.03%を超えるとその悪影響が顕著になるので、S量は0.03%以下とした。
(S: 0.03% or less)
S combines with Mn to form MnS and serves as an initial starting point. S is also a harmful element that segregates at the grain boundaries and promotes embrittlement of the grain boundaries, so it is preferable to reduce S as much as possible. In particular, when the S content exceeds 0.03%, the adverse effect becomes remarkable, so the S content is set to 0.03% or less.
(Cr:10.50%以上13.50%以下)
Crは、本発明における耐食性発現成分として重要な元素である。本発明で対象にする鉄筋として、コンクリート中において塩化物イオン濃度に対する耐食性を確保するためには、少なくとも 10.50%以上のCrが必要である。一方、Cr量が13.50%超になると、耐食性は良くなるものの、フェライト相の生成量が多くなって溶接部の靱性不足となることやコストアップに繋がる。従って、Cr量は10.50 %以上13.50%以下とした。
(Cr: 10.50% to 13.50%)
Cr is an important element as a corrosion resistance developing component in the present invention. In order to ensure the corrosion resistance against chloride ion concentration in the concrete as a reinforcing bar targeted in the present invention, at least 10.50% or more of Cr is necessary. On the other hand, if the Cr content exceeds 13.50%, the corrosion resistance is improved, but the amount of ferrite phase generated is increased, leading to insufficient toughness of the welded part and an increase in cost. Therefore, the Cr content is set to 10.50% or more and 13.50% or less.
(Ni:0.6%以下)
Niは、過剰に添加するとマルテンサイト組織が析出し加工性を劣化させるため、上限を0.6%とした。また、靱性を高めるために0.05質量%以上添加することが望ましい。
(Ni: 0.6% or less)
When Ni is added excessively, a martensite structure precipitates and deteriorates workability, so the upper limit was made 0.6%. Moreover, in order to improve toughness, it is desirable to add 0.05 mass% or more.
(N:0.1%以下)
Nは、オーステナイト相および窒化物の生成元素であり強度を高めるが、耐食性、靭性を劣化させるため上限を0.1%とした。また、0.001質量%未満ではオーステナイト相や窒化物の生成が少なく強度向上の効果が得られないため0.001質量%以上添加することが望ましい。
なお、以上の元素以外の成分は特に規定しないが、Feおよび不可避的不純物からなる。
(N: 0.1% or less)
N is an element forming the austenite phase and nitride and increases the strength. However, the upper limit is set to 0.1% in order to deteriorate the corrosion resistance and toughness. Further, if it is less than 0.001% by mass, an austenite phase and a nitride are formed little and an effect of improving the strength cannot be obtained, so 0.001% by mass or more is preferably added.
In addition, although components other than the above elements are not specifically defined, it consists of Fe and inevitable impurities.
次に、節が軸線方向のリブに対し30度〜85度あるいは95度から150度の角度で交わり、節の高さが公称直径の4.0%以上10.0%以下であり、同方向の節と節の間隔が公称直径の0.5倍以上2.0倍以内であることを規定した理由について示す。 Next, the nodes intersect with the axial rib at an angle of 30 to 85 degrees or 95 to 150 degrees, and the height of the nodes is 4.0% or more and 10.0% or less of the nominal diameter. The reason why it is specified that the distance between the nodes is 0.5 to 2.0 times the nominal diameter will be described.
コンクリートの付着強度は、節のリブに対する角度、節の高さ、節と節の間隔に依存する。その概略を図1に示す。
図1(a)は本発明のステンレス異形棒鋼の側面図、図1(b)はA-A断面図およびB−B断面図、図1(b)は斜視図を示しており、本発明のステンレス異形棒鋼は、表面の軸線方向に設けられたリブと、該リブと交差する節とを有している。
節とリブの角度は30度〜85度あるいは95度から150度の角度であれば、30度未満あるいは150度超ではコンクリートの付着強度が小さくなって節の効果を果さない。また、一般的な節とリブが90度の鉄筋を含め、節とリブの角度が85度超95度未満の場合、棒鋼を垂直に立ててコンクリートを打設した時に気泡が節にトラップされて逃げ難くなるため、施工後コンクリートと異形棒鋼の界面で隙間が形成され易くなり、密着性が下がることに加え、鉄筋表面の水分や酸素量も多くなるので腐食しやすくなる。したがって、鉄筋を垂直、または水平に使用した場合に、気泡が節にたまりにくくなり、コンクリートの付着強度が向上するように、節とリブの角度は30度以上85度以下あるいは95度以上150度以下の角度とした。
The bond strength of concrete depends on the angle of the nodes to the ribs, the height of the nodes, and the distance between the nodes. The outline is shown in FIG.
FIG. 1 (a) is a side view of a stainless deformed steel bar according to the present invention, FIG. 1 (b) is a cross-sectional view along AA and BB, and FIG. 1 (b) is a perspective view. The stainless steel deformed steel bar has a rib provided in the axial direction of the surface and a node intersecting with the rib.
If the angle between the nodes and the ribs is an angle of 30 to 85 degrees or 95 to 150 degrees, if the angle is less than 30 degrees or more than 150 degrees, the adhesion strength of the concrete becomes small and the effect of the nodes is not achieved. Also, when the angle between the joint and rib is more than 85 degrees and less than 95 degrees, including the 90-degree reinforcing bar, the bubbles are trapped in the joint when concrete is placed with the steel bar standing vertically. Since it becomes difficult to escape, gaps are likely to be formed at the interface between concrete and deformed steel bar after construction, and in addition to the decrease in adhesion, the surface of the reinforcing bar is also susceptible to corrosion due to an increased amount of moisture and oxygen. Therefore, when the reinforcing bars are used vertically or horizontally, the angle between the nodes and the ribs is 30 degrees or more and 85 degrees or less, or 95 degrees or more and 150 degrees so that the bubbles are less likely to collect in the nodes and the adhesion strength of the concrete is improved. The following angles were used.
節の高さは、JISG3112に規定されている範囲で十分な付着強度が得られるため、節の高さを公称直径の4.0%以上10.0%以下とした。 As the height of the node is sufficient in the range specified in JIS G3112, the height of the node is set to 4.0% to 10.0% of the nominal diameter.
リブに対して同方向の節と節との間隔を公称直径の0.5倍以上2.0倍以内とした理由は、0.5倍未満であると間隔が狭く節の間にコンクリートが入りにくくなり付着強度が低下する。また、2.0倍超であると間隔が離れすぎ、付着強度が低下する。そのため同方向の節と節の間隔を公称直径の0.5倍以上2.0倍以内とした。 The reason why the distance between the nodes in the same direction with respect to the ribs is 0.5 times or more and 2.0 times the nominal diameter is less than 0.5 times, the space is narrow and concrete enters between the nodes. It becomes difficult and adhesion strength falls. On the other hand, if it is more than 2.0 times, the distance is too far and the adhesion strength decreases. Therefore, the distance between nodes in the same direction is set to be 0.5 times or more and 2.0 times or less of the nominal diameter.
また、リブに対し2つ以上の方向の節を有する方がコンクリートの滑りに対する抵抗力が増し付着強度が向上するため、2つ以上の方向の節を有することが望ましい。
また、節の幅に関しては特に規定しないが、小さすぎると疵が付きやすく曲げ加工を行った場合に割れの起点となり易い。また大きすぎると節の表面においてコンクリートとの滑りが生じ易くなり付着強度向上の効果が無くなる。以上より節の幅は1mm以上10mm以下が望ましい。
In addition, it is desirable to have nodes in two or more directions since the resistance to the slip of the concrete is increased and the adhesion strength is improved if the ribs have nodes in two or more directions with respect to the ribs.
Further, the width of the node is not particularly specified, but if it is too small, it tends to be wrinkled and easily becomes a starting point of cracking when bending is performed. On the other hand, if it is too large, slippage with the concrete tends to occur on the surface of the node, and the effect of improving the adhesion strength is lost. Therefore, the width of the node is preferably 1 mm or more and 10 mm or less.
また合金指標に関しては、合金成分量と0.2%耐力の関係を調査した結果、熱間圧延中でのオーステナイト組織の生成量の目安となる指標
γp=700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2と0.2%耐力が図1に示すように良い相関を示すことを見出した。すなわち
ステンレス異形棒鋼の実用的な強度レベルとして、
γp=≧0で0.2%耐力が295MPa以上、
あるいは、
γp=≧10で0.2%耐力が345MPa以上、
あるいは、
γp=≧15で0.2%耐力が390MPa以上と規定するものである。
また、鉄筋表面の脱スケールに関しては、脱スケールを施したものは、施さないものに比べ、表面の耐食性が良くなり、発錆しにくくなる。これは、耐食性の低いFe、Cr酸化物とその下地のCr欠乏層を取り除くことにより、健全な不動態皮膜が形成するため、脱スケールを施したものは耐食性が良くなる。
As for the alloy index, as a result of investigating the relationship between the alloy component amount and the 0.2% yield strength, an index γp = 700 × (C) + 20 × (Ni, which is a standard for the amount of austenite structure formed during hot rolling. ) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
It was found that −37 × (Al) +63.2 and 0.2% proof stress showed a good correlation as shown in FIG. In other words, as a practical strength level of stainless steel bar
γp = ≧ 0 and 0.2% proof stress is 295 MPa or more,
Or
γp = ≧ 10 and 0.2% proof stress is 345 MPa or more,
Or
It is specified that 0.2% proof stress is 390 MPa or more when γp = ≧ 15.
Further, regarding the descaling of the reinforcing bar surface, the descaled one has better surface corrosion resistance and is less susceptible to rusting than the unscaled one. This is because a healthy passive film is formed by removing the Fe and Cr oxides having low corrosion resistance and the underlying Cr-deficient layer, so that the descaled one has better corrosion resistance.
なお、本発明鋼の製造に際しては、特別な制限はなく、常法に従って製造すれば良い。参考のため、代表的な製造条件を以下に示す。
(1)溶製
スクラップ等のFe、Cr原料を電気炉にて溶解した溶鋼を、AOD等により脱炭 、成分調整したものを、連続鋳造にてビレットを製造する。
(2)熱間圧延
ビレットを、1100〜1200℃に加熱したのち、熱間圧延の最終ロー ルにて異形形状を付与するロールにて圧延を行い、異形形状を有する棒鋼あ るいは線材コイルとする。なお、異形形状を付与する方法は、熱間鍛造等に よる方法もある。
(3)仕上工程
熱間圧延により製造した棒鋼あるいは線材は、矯直等を施して使用すること が可能であるが、必要に応じて適当な熱処理により強度を調整する。また、 より耐食性を向上させる場合には、熱間圧延後、場合によっては、ショット ブラスト、さらには硝酸+弗酸等による脱スケール処理を施す。
In addition, when manufacturing the steel of the present invention, there is no special limitation, and it may be manufactured according to a conventional method. For reference, typical production conditions are shown below.
(1) Melting Billet is produced by continuous casting of molten steel in which Fe and Cr raw materials such as scrap are melted in an electric furnace, decarburized with AOD, etc., and the components are adjusted.
(2) Hot rolling After the billet is heated to 1100-1200 ° C, it is rolled with a roll that gives a deformed shape at the final roll of hot rolling, and a steel bar or wire coil having a deformed shape is formed. To do. In addition, there is also a method using hot forging or the like as a method for imparting an irregular shape.
(3) Finishing process The steel bar or wire rod manufactured by hot rolling can be used after being straightened, but the strength is adjusted by an appropriate heat treatment if necessary. In order to further improve the corrosion resistance, after hot rolling, in some cases, a descaling process is performed by shot blasting, and further nitric acid + hydrofluoric acid.
表1に示す成分組成になる50kg鋼塊を真空溶解した。ついで、鋼塊の表面5mmを研削したのち、1200℃、1時間の焼鈍を施し、900℃における熱間圧延により13mmφ〜25mmφの異形棒鋼とした。一部の製品については780℃、1時間空冷の調質焼鈍を施した。一部この棒鋼に、ショットブラストと弗酸−硝酸の混合酸による脱スケール処理を施した。 A 50 kg steel ingot having the composition shown in Table 1 was melted in vacuo. Next, after grinding the surface of the steel ingot 5 mm, annealing was performed at 1200 ° C. for 1 hour, and hot rolled at 900 ° C. to obtain a deformed bar steel having a diameter of 13 mmφ to 25 mmφ. Some products were tempered by air cooling at 780 ° C. for 1 hour. Part of this steel bar was descaled with a mixed acid of shot blasting and hydrofluoric acid-nitric acid.
鉄筋コンクリート製造条件として、粗骨材 981 kg/m3 、細骨材853 kg/m3 、ポルトランドセメント300 kg/m3、水 190 kg/m3 の組成のコンクリートをJIS A1132:1999に準じ1辺が15cmの立方形供試体を作製した(材齢28日)。JICE G503.1999に準じ28日間20℃水中養生を行った後付着強度試験を行った。その結果を表1の最大付着応力度に示す。また、JIS Z2241:1998により鉄筋の引張り試験を実施した。その結果を表1の0.2%耐力に示す。
As for the conditions for producing reinforced concrete, a concrete having a composition of coarse aggregate 981 kg / m3, fine aggregate 853 kg / m3,
40℃コンクリート環境の模擬水溶液(飽和Ca(OH)2溶液に所定のCl- 濃度までNaClを加えたもの)中に異形棒鋼(長さ60mm)を浸漬し、発錆の 有無により耐食性を評価した。2%Cl-濃度の方が、0.02%Cl-濃 度より、腐食環境が厳しく発錆しやすいので、脱スケールを施したものは、 2%Cl-で試験を行い、脱スケールを施さないものは、0.02%Cl- にて試験を行った。その結果を表1に発錆の有無にて示す。 40 ° C. simulated aqueous concrete environment (saturated Ca (OH) 2 solution to a predetermined Cl - as NaCl was added to a concentration) was immersed deformed steel bars (length 60 mm) into and evaluated the corrosion resistance by the presence or absence of rusting . 2% Cl - towards concentration, 0.02% Cl - than concentration, since corrosive environment severely rust easily, which was subjected to de-scale, 2% Cl - in performed tests, subjected to descaling nothing is, 0.02% Cl - were tested at. The results are shown in Table 1 by the presence or absence of rusting.
表1のNo.1〜No.11については本発明の節の形状を変化させた場合の効果を示す。No.12〜No.15についてはNo.1に対して本発明の合金成分・合金指標を変化させた場合の効果を示す。No.16〜No.25についてはNo.1に対して本発明の合金成分・合金指標・公称直径・節の高さを変化させた場合の効果を示す。そのうちNo.25は、熱間圧延後、調質焼鈍を施したものである。No.26は、No.1と同成分・同節形状で脱スケールを施さないものである。表1に示すように、本発明のステンレス異形棒鋼は比較例と比べて耐食性・付着強度ともに高く良好であった。
比較例をNo.27〜31に示す。No.27は節の角度が小さいため付着強度が小さかった。No.28は節の高さが小さいため、付着強度が小さかった。
No.29は節の間隔が大きすぎるため、付着強度が小さかった。
No.30は鋼中Cr量が低いため耐食性が低下し、40℃飽和Ca(OH)2、2%Cl-溶液浸漬試験の結果、発錆した。No.31は鋼中Cr量が高く耐食性も高いが、コストも高くなる。
No. in Table 1 1-No. 11 shows the effect when the shape of the node of the present invention is changed. No. 12-No. No. 15 for No. 1 shows the effect of changing the alloy component / alloy index of the present invention. No. 16-No. For No. 25, no. 1 shows the effect of changing the alloy composition, alloy index, nominal diameter, and node height of the present invention. No. No. 25 is subjected to temper annealing after hot rolling. No. 26 is No. 26. The same component and the same joint shape as No. 1 are not descaled. As shown in Table 1, the stainless steel deformed steel bar of the present invention was excellent in both corrosion resistance and adhesion strength as compared with the comparative example.
Comparative example No. 27-31. No. No. 27 had a low adhesion strength because the angle of the node was small. No. Since No. 28 had a small node height, its adhesion strength was small.
No. In No. 29, the knot spacing was too large, so the adhesion strength was small.
No. 30 is lowered corrosion resistance due to the low amount of Cr in steel, 40 ° C. saturated Ca (OH) 2,2% Cl - solution immersion test results were rusting. No. No. 31 has a high Cr content in steel and high corrosion resistance, but the cost is also high.
また、コンクリート質量(2260kg/m3)に対しNaClにて0.12%のCl -を加え、本発明の異形棒鋼(No.1)と同形状の普通鋼の異形棒鋼(No. 32)をそれぞれ埋め込んだ、1辺が15cmの立方形供試体を作製した(材 齢28日)。その試験体を40℃相対湿度60%の恒温恒湿槽内に6ケ月間保 持したのち、付着強度試験を実施した。その結果を表2の腐食試験前後の最 大付着応力度に示す。 In addition, 0.12% Cl − was added with NaCl to the concrete mass (2260 kg / m 3), and the deformed steel bar (No. 32) of the same shape as the deformed steel bar (No. 1) of the present invention was added. An embedded cubic specimen having a side of 15 cm was prepared (age 28 days). The specimen was held in a constant temperature and humidity chamber at 40 ° C. and 60% relative humidity for 6 months, and then an adhesion strength test was performed. The results are shown in Table 2 for the maximum adhesion stress before and after the corrosion test.
表2のNo.38に示すように普通鋼鉄筋がコンクリート中の塩化物イオンによって発錆した場合、錆による体積膨張によってコンクリートにひびが入り、また腐食により節形状が損なわれたため、付着強度の低下がみられた。しかし本発明の棒鋼を鉄筋として使用した場合、同濃度の塩化物イオンによる発錆はみられなく、腐食により節形状が損なわれることもないため、付着強度の低下もみられなかった。すなわち本発明の異形棒鋼については、高い耐食性によって棒鋼自身が損傷されること無く、コンクリートへの悪影響も無く付着強度も長期間維持されるという相乗効果が認められた。
Claims (6)
C :0.15%以下、
Si:2.0%以下、
Mn:2.0%以下、
P:0.04%以下、
S:0.03%以下、
Cr:10.50〜13.50%を含み、
表面の軸線方向に設けられたリブと、該リブと交差する節とを有しており、
少なくとも一つの節が前記リブに対し30度〜85度または95度〜150度の角度で交わり、該節の高さが公称直径の4.0%以上10.0%以下で、前記リブに対し同方向の節と節の間隔が公称直径の0.5倍以上2.0倍以内であることを特徴とする、コンクリート構造物中における耐久性に優れたステンレス異形棒鋼。 % By mass
C: 0.15% or less,
Si: 2.0% or less,
Mn: 2.0% or less,
P: 0.04% or less,
S: 0.03% or less,
Cr: 10.50 to 13.50% included,
A rib provided in the axial direction of the surface, and a node intersecting with the rib;
At least one node intersects the rib at an angle of 30 to 85 degrees or 95 to 150 degrees, and the height of the node is not less than 4.0% and not more than 10.0% of the nominal diameter; Stainless deformed steel bar with excellent durability in concrete structures, characterized in that the distance between nodes in the same direction is 0.5 times or more and 2.0 times the nominal diameter.
C :0.15%以下、
Si:2.0%以下、
Mn:2.0%以下、
P:0.04%以下、
S:0.03%以下、
Cr:10.50〜13.50%を含み、
0.2%耐力が295MPa以上を有し、
表面の軸線方向に設けられたリブと、該リブと交差する節とを有しており、
少なくとも一つの節が前記リブに対し30度〜85度または95度〜150度の角度で交わり、該節の高さが公称直径の4.0%以上10.0%以下で、前記リブに対し同方向の節と節の間隔が公称直径の0.5倍以上2.0倍以内であることを特徴とする、コンクリート構造物中における耐久性に優れたステンレス異形棒鋼。 % By mass
C: 0.15% or less,
Si: 2.0% or less,
Mn: 2.0% or less,
P: 0.04% or less,
S: 0.03% or less,
Cr: 10.50 to 13.50% included,
0.2% proof stress is 295 MPa or more,
A rib provided in the axial direction of the surface, and a node intersecting with the rib;
At least one node intersects the rib at an angle of 30 to 85 degrees or 95 to 150 degrees, and the height of the node is not less than 4.0% and not more than 10.0% of the nominal diameter; Stainless deformed steel bar with excellent durability in concrete structures, characterized in that the distance between nodes in the same direction is 0.5 times or more and 2.0 times the nominal diameter.
Ni:0.6%以下、
N::0.1%以下、
γp= 700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2≧0で、
0.2%耐力が295MPa以上であることを特徴とする、請求項1または請求項2に記載のコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。 Furthermore, in mass%,
Ni: 0.6% or less,
N :: 0.1% or less,
γ p = 700 × (C) + 20 × (Ni) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
−37 × (Al) + 63.2 ≧ 0,
The stainless deformed steel bar having excellent durability in a concrete structure according to claim 1 or 2, wherein 0.2% proof stress is 295 MPa or more.
Ni:0.6%以下、
N::0.1%以下、
γp= 700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2≧10で、
0.2%耐力が345MPa以上であることを特徴とする、請求項1または請求項2に記載のコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。 Furthermore, in mass%,
Ni: 0.6% or less,
N :: 0.1% or less,
γ p = 700 × (C) + 20 × (Ni) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
−37 × (Al) + 63.2 ≧ 10,
The stainless deformed steel bar excellent in durability in a concrete structure according to claim 1 or 2, wherein the 0.2% proof stress is 345 MPa or more.
Ni:0.66%以下、
N::0.1%以下、
γp= 700×(C)+20×(Ni)+800×(N)+10×(Mn)
−6.2×(Cr)−9.2×(Si)+10×(Cu)
−9.3×(Mo)−74.4(Ti)−3.1×(Nb)
−37×(Al)+63.2≧15で、
0.2%耐力が390MPa以上であることを特徴とする、請求項1または請求項2に記載のコンクリート構造物中における耐久性に優れたステンレス異形棒鋼。 Furthermore, in mass%,
Ni: 0.66% or less,
N :: 0.1% or less,
γ p = 700 × (C) + 20 × (Ni) + 800 × (N) + 10 × (Mn)
−6.2 × (Cr) −9.2 × (Si) + 10 × (Cu)
−9.3 × (Mo) −74.4 (Ti) −3.1 × (Nb)
−37 × (Al) + 63.2 ≧ 15,
The stainless deformed steel bar excellent in durability in a concrete structure according to claim 1 or 2, wherein the 0.2% proof stress is 390 MPa or more.
The stainless deformed steel bar according to any one of claims 1 to 5, wherein the outer surface is descaled, and the stainless deformed steel bar having excellent durability in a concrete structure.
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JP2009214160A (en) * | 2008-03-12 | 2009-09-24 | Mizushima General Service Kk | Method for bending shear reinforcement wire |
JP2011026686A (en) * | 2009-07-29 | 2011-02-10 | Aichi Steel Works Ltd | Method for manufacturing chromium-based stainless-steel reinforcing bar |
JP2012057338A (en) * | 2010-09-08 | 2012-03-22 | Kiyomiya Osamu | Concrete structure member using stainless steel reinforcing bars |
JP2013040550A (en) * | 2011-07-19 | 2013-02-28 | Hamanaka Nut Kk | Screw-knotted reinforcement and method of manufacturing the same |
JP2013227818A (en) * | 2012-04-26 | 2013-11-07 | Aiko Kk | Deformed stainless steel rod material for concrete reinforcement |
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JP5934550B2 (en) * | 2012-03-30 | 2016-06-15 | 新日鐵住金ステンレス株式会社 | Chromium-containing deformed steel bar with excellent corrosion resistance in concrete structures |
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