JP2018040031A - Steel material for structure excellent in coating durability and structure - Google Patents
Steel material for structure excellent in coating durability and structure Download PDFInfo
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- 239000011248 coating agent Substances 0.000 title claims abstract description 74
- 238000000576 coating method Methods 0.000 title claims abstract description 74
- 239000000463 material Substances 0.000 title claims abstract description 73
- 229910000831 Steel Inorganic materials 0.000 title abstract description 71
- 239000010959 steel Substances 0.000 title abstract description 71
- 239000000203 mixture Substances 0.000 claims abstract description 18
- 229910052742 iron Inorganic materials 0.000 claims abstract description 13
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910000746 Structural steel Inorganic materials 0.000 claims description 32
- 239000003973 paint Substances 0.000 claims description 19
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 5
- 239000003822 epoxy resin Substances 0.000 claims description 5
- 229920000647 polyepoxide Polymers 0.000 claims description 5
- 229910052725 zinc Inorganic materials 0.000 claims description 5
- 239000011701 zinc Substances 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 25
- 229910052759 nickel Inorganic materials 0.000 abstract description 15
- 229910052802 copper Inorganic materials 0.000 abstract description 14
- 229910045601 alloy Inorganic materials 0.000 abstract description 10
- 239000000956 alloy Substances 0.000 abstract description 10
- 229910052787 antimony Inorganic materials 0.000 abstract description 9
- 229910052721 tungsten Inorganic materials 0.000 abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 4
- 229910052710 silicon Inorganic materials 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 2
- 229910052717 sulfur Inorganic materials 0.000 abstract description 2
- 229910052748 manganese Inorganic materials 0.000 abstract 1
- 239000010410 layer Substances 0.000 description 36
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 29
- 230000007797 corrosion Effects 0.000 description 22
- 238000005260 corrosion Methods 0.000 description 22
- 230000000694 effects Effects 0.000 description 22
- 238000012360 testing method Methods 0.000 description 14
- 235000002639 sodium chloride Nutrition 0.000 description 13
- 229910052718 tin Inorganic materials 0.000 description 13
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 8
- 229910052804 chromium Inorganic materials 0.000 description 7
- 238000010422 painting Methods 0.000 description 7
- 230000001737 promoting effect Effects 0.000 description 7
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000007670 refining Methods 0.000 description 5
- 239000011780 sodium chloride Substances 0.000 description 5
- 230000002195 synergetic effect Effects 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 230000008961 swelling Effects 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 230000035515 penetration Effects 0.000 description 3
- 239000012466 permeate Substances 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000004993 emission spectroscopy Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000005098 hot rolling Methods 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 229910052750 molybdenum Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000009628 steelmaking Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 229910000870 Weathering steel Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007865 diluting Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 238000004949 mass spectrometry Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000003303 reheating Methods 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
- 239000000565 sealant Substances 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Abstract
Description
本発明は、主に橋梁などの屋外の大気腐食環境下、特には飛来塩分量の多い海上や海岸近傍などの厳しい腐食環境下の構造物に用いられる塗装耐久性に優れた構造用鋼材に関するものである。 TECHNICAL FIELD The present invention relates to a structural steel material having excellent paint durability, which is mainly used for structures under outdoor atmospheric corrosive environments such as bridges, particularly in severe corrosive environments such as the sea and coastal areas where the amount of incoming salt is high. It is.
橋梁などの屋外で用いられる鋼構造物は、通常、何らかの防食処理を施して用いられる。例えば、飛来塩分量が少ない環境では、耐候性鋼が多く用いられている。 Steel structures used outdoors such as bridges are usually used after being subjected to some anticorrosion treatment. For example, in an environment where the amount of incoming salt is small, weathering steel is often used.
ここで、耐候性鋼は、大気暴露環境で使用する場合に、Ｃｕ、Ｐ、Ｃｒ、Ｎｉなどの合金元素が濃化した保護性の高いさび層で表面が覆われ、これによって、腐食速度を大きく低下させた鋼材である。このような耐候性鋼を使用した橋梁は、飛来塩分量が少ない環境では、無塗装のまま数十年間の供用に耐え得ることが知られている。 Here, the weather-resistant steel is covered with a highly protective rust layer enriched with alloy elements such as Cu, P, Cr, and Ni when used in an atmospheric exposure environment. It is a steel material greatly reduced. It is known that bridges using such weather-resistant steel can withstand service for several decades without painting in an environment where the amount of incoming salt is low.
一方、海上や海岸近傍などの飛来塩分量の多い環境では、耐候性鋼において保護性の高いさび層が形成され難く、耐候性鋼を無塗装のまま使用することは困難である。このため、海上や海岸近傍などの飛来塩分量の多い環境では、普通鋼材に塗装などの防食処理を施した鋼材が一般的に用いられている。 On the other hand, in an environment with a large amount of incoming salt, such as at sea or in the vicinity of the coast, it is difficult to form a highly protective rust layer in the weather resistant steel, and it is difficult to use the weather resistant steel without coating. For this reason, in the environment where there is a large amount of incoming salt, such as at sea or in the vicinity of the shore, steel materials obtained by subjecting ordinary steel materials to anticorrosion treatment such as painting are generally used.
しかしながら、塗装鋼材では、時間の経過による塗膜の劣化やさびの発生、塗膜の膨れ等により、定期的な塗り替えなどの補修が必要となる。塗り替えに伴う塗装作業は、高所での作業となることが多く、作業自体が困難であるとともに、作業にかかる人件費も必要となる。そのため、塗装鋼材を使用する場合には、構造物のメンテナンスコストが増大し、ひいてはライフサイクルコストが増大するという問題がある。 However, in coated steel materials, repair such as periodic repainting is necessary due to deterioration of the coating film, generation of rust, swelling of the coating film, etc. over time. The painting work associated with repainting is often a work at a high place, and the work itself is difficult and labor costs for the work are also required. Therefore, when using painted steel, there is a problem that the maintenance cost of the structure increases, and consequently the life cycle cost increases.
このようなことから、塗り替え塗装の周期を延長することによって、塗装頻度を低減し、構造物のメンテナンスコストを抑制可能な耐食性に優れた鋼材、特には塗装耐久性に優れた構造用鋼材の開発が望まれている。 Therefore, by extending the period of repainting, the development of steel materials with excellent corrosion resistance that can reduce the frequency of painting and reduce the maintenance cost of structures, especially structural steel materials with excellent coating durability. Is desired.
このような耐食性に優れた鋼材として、例えば、特許文献１には、Ｐを０．１５〜０．３０％、Ｃｒを２.０％超え３.０％未満含有させた高耐候性鋼材が開示されている。
特許文献２には、Ｐを０．０３〜０．１５％、Ｃｕを０．２〜０．５％含有させた超塗装耐久性鋼材が開示されている。
特許文献３には、Ｃｕを０．０５〜３．０％、Ｎｉを０．０５〜６．０％、Ｔｉを０．０１〜１．０％含有させた耐久性に優れた塗装鋼材が開示されている。
特許文献４には、Ｃｕを０．０５〜３．０％、Ｎｉを０．０５〜６．０％、Ｔｉを０．０２５〜０．１５％含有させた塗膜耐久性に優れた塗装用鋼材が開示されている。
特許文献５には、Ｃｕを０．３０〜１．００％、Ｎｉを１．０〜５．５％含有させた高溶接性高耐候性鋼が開示されている。
特許文献６には、Ｃｕを０．０５〜１．０％、Ｎｉを０．０１〜０．５％、Ｃｒを０．０１〜３．０％、Ｓｎおよび／またはＳｂを０．０３〜０．５０％含有させた海浜耐候性に優れた鋼材が開示されている。
特許文献７には、Ｃｒを０．０１〜３．０％、Ｓｎを０．０３〜０．５０％含有させた耐食性およびＺ方向の靱性に優れた鋼材の製造方法が開示されている。
特許文献８には、Ｓｎを０．１５〜０．５％含有させた、塩化物を含む乾湿繰り返し環境下で用いられる耐食性に優れた鋼材が開示されている。
特許文献９には、Ｃｒを２．６〜１３．０％、Ｓｎを０．０１〜０．５％含有させた、耐食性に優れた鋼材が開示されている。
As such steel material having excellent corrosion resistance, for example, Patent Document 1 discloses a highly weather-resistant steel material containing 0.15 to 0.30% P and 2.0% to less than 3.0% Cr. Has been.
Patent Document 2 discloses a superpaint durable steel material containing 0.03 to 0.15% P and 0.2 to 0.5% Cu.
Patent Document 3 discloses a coated steel material excellent in durability containing 0.05 to 3.0% of Cu, 0.05 to 6.0% of Ni, and 0.01 to 1.0% of Ti. Has been.
Patent Document 4 describes a coating film having 0.05 to 3.0% Cu, 0.05 to 6.0% Ni, and 0.025 to 0.15% Ti, and having excellent coating film durability. Steel is disclosed.
Patent Document 5 discloses a high weldability and weather resistant steel containing 0.30 to 1.00% Cu and 1.0 to 5.5% Ni.
In Patent Document 6, Cu is 0.05 to 1.0%, Ni is 0.01 to 0.5%, Cr is 0.01 to 3.0%, Sn and / or Sb is 0.03 to 0%. Steel materials excellent in beach weather resistance containing 50% are disclosed.
Patent Document 7 discloses a method for producing a steel material excellent in corrosion resistance and toughness in the Z direction, containing 0.01 to 3.0% Cr and 0.03 to 0.50% Sn.
Patent Document 8 discloses a steel material containing 0.15 to 0.5% of Sn and having excellent corrosion resistance that is used in a dry and wet environment containing chloride.
Patent Document 9 discloses a steel material excellent in corrosion resistance containing 2.6 to 13.0% Cr and 0.01 to 0.5% Sn.
しかしながら、特許文献１および２のようにＰの含有量を増加させると、溶接性が大きく低下する。さらに、特許文献１では、塗装した鋼材の耐食性、すなわち塗装耐久性について、何ら考慮が払われていない。 However, when the P content is increased as in Patent Documents 1 and 2, the weldability is greatly reduced. Furthermore, in Patent Document 1, no consideration is given to the corrosion resistance of the coated steel material, that is, the coating durability.
また、特許文献３、４および５のように、ＣｕやＮｉの含有量を過度に増加させると、合金コストの増大を招く。さらに、特許文献３および４のようにＴｉを多量に含有させると、鋼材の靱性の劣化を招く。加えて、特許文献６〜９のように、ＣｒやＳｎなどの含有量を過度に増加させると、やはり合金コストの増大を招くとともに、鋼材の靱性の劣化を招く。 Further, as in Patent Documents 3, 4 and 5, excessively increasing the content of Cu or Ni causes an increase in alloy cost. Furthermore, when a large amount of Ti is contained as in Patent Documents 3 and 4, the toughness of the steel material is deteriorated. In addition, as in Patent Documents 6 to 9, excessively increasing the content of Cr, Sn, etc., also causes an increase in alloy cost and a deterioration in the toughness of the steel material.
本発明は、上記の現状に鑑み開発されたものであって、合金コストの過度の増大を招くことなく、橋梁などの屋外の大気腐食環境下、特には飛来塩分量の多い海上や海岸近傍などの厳しい腐食環境下で使用する場合であっても、塗り替え塗装にかかる周期を延長して、塗装頻度を低減することが可能な塗装耐久性に優れた構造用鋼材を提供することを目的とする。
なお、「塗装耐久性に優れた」とは、鋼板表面に塗膜を形成し、以下の条件の腐食試験を行ったときの塗膜の膨れ面積が４８０ｍｍ２以下であることを意味する。
・腐食試験条件
塗膜に付与する初期欠陥：幅１ｍｍ、長さ４０ｍｍの直線のカット
人工海塩の付着量：６．０ｇ／ｍ２
試験時間：１２００サイクル（９６００時間）
サイクル条件：（条件１．温度：６０℃、相対湿度：３５％、保持時間：３時間）、（条件２．温度：４０度、相対湿度：９５％、保持時間：３時間）、条件１から条件２および条件２から条件１への各移行時間を１時間とする、合計８時間のサイクル
The present invention was developed in view of the above-mentioned present situation, and does not cause an excessive increase in alloy costs, and under an outdoor atmospheric corrosive environment such as a bridge, particularly on the sea or in the vicinity of the coast where the amount of incoming salt is high. Even when used in severe corrosive environments, the purpose is to provide structural steel materials with excellent paint durability that can extend the period of repainting and reduce the frequency of painting. .
“Excellent coating durability” means that the swollen area of the coating film is 480 mm 2 or less when a coating film is formed on the steel sheet surface and the corrosion test under the following conditions is performed.
Corrosion test conditions Initial defects to be applied to the coating film: straight cut with a width of 1 mm and a length of 40 mm Amount of artificial sea salt deposited: 6.0 g / m 2
Test time: 1200 cycles (9600 hours)
Cycle conditions: (Condition 1. Temperature: 60 ° C., relative humidity: 35%, retention time: 3 hours), (Condition 2. Temperature: 40 degrees, relative humidity: 95%, retention time: 3 hours), from condition 1 A cycle of 8 hours in total, with each transition time from condition 2 and condition 2 to condition 1 being 1 hour
さて、発明者らは、合金コストの増大や靭性の劣化を招くおそれのあるＣｕやＮｉ、Ｃｒ、Ｓｎなどを多量に含有させることなく、優れた塗装耐久性を得るべく、種々の成分組成となる鋼材を作製し、その塗装耐久性を調査した。
その結果、Ｓｉ量を適正な範囲に調整したうえで、ＣｕやＮｉ、Ｓｎ、Ｓｂをそれぞれ微量複合添加し、さらにＷを添加することによって、塗装耐久性を大幅に向上することを見出した。
Now, the inventors have various component compositions to obtain excellent coating durability without containing a large amount of Cu, Ni, Cr, Sn, etc., which may cause an increase in alloy cost and deterioration of toughness. Steel materials were manufactured and their coating durability was investigated.
As a result, it was found that the coating durability was greatly improved by adding a small amount of each of Cu, Ni, Sn, and Sb and further adding W after adjusting the Si amount to an appropriate range.
この理由については必ずしも明らかではないが、発明者らは次のように考えている。
（１）Ｓｉ、ＣｕおよびＮｉは、さび粒子を微細化させることでさび層を緻密化させ、腐食促進因子である酸素や塩化物イオンがさび層を透過して地鉄に到達するのを防止する。また、これらの元素は、ナトリウムイオンがさび層を透過して塗膜膨れ先端のカソード部に供給されるのを防止する。
（２）Ｗは、地鉄表面近傍さび層中にＷＯ４ ２−として存在することで、腐食促進因子である塩化物イオンがさび層を透過して地鉄に到達するのを防止する。さらに、鋼材表面にＷを含む化合物が沈殿することでアノード反応を抑制する。
（３）ＳｎおよびＳｂは、地鉄表面近傍においてさび層中に存在し、さび粒子を微細化することで腐食促進因子である塩化物イオンがさび層を透過して地鉄に到達するのを防止する。また、鋼材表面においてアノード反応を抑制する。
（４）そして、耐食性向上効果を最大限発現にさせるには、上記の元素のなかでもＳｉを積極的に活用することが重要であり、このＳｉ含有量を適正な範囲に調整して、ＣｕやＮｉ、Ｓｎ、Ｓｂといった元素をそれぞれ微量に複合添加し、さらにＷを添加することによって、各元素の耐食性向上効果が相乗して得られ、ＣｕやＮｉ、Ｓｎ、Ｓｂといった元素を大量には含有させずとも、耐食性、特には塗装耐久性が大幅に向上する。
本発明は、上記の知見に基づき、さらに検討を重ねて完成させたものである。
Although this reason is not necessarily clear, the inventors consider as follows.
(1) Si, Cu and Ni densify rust particles by densifying rust particles and prevent oxygen and chloride ions, which are corrosion promoting factors, from passing through the rust layer and reaching the iron To do. Further, these elements prevent sodium ions from passing through the rust layer and being supplied to the cathode portion at the tip of the swollen coating film.
(2) W is present as WO 4 2− in the rust layer near the surface of the ground iron, thereby preventing chloride ions, which are corrosion promoting factors, from passing through the rust layer and reaching the ground iron. Furthermore, the anode reaction is suppressed by precipitation of a compound containing W on the steel material surface.
(3) Sn and Sb are present in the rust layer in the vicinity of the surface of the ground iron. By making the rust particles finer, chloride ions, which are corrosion promoting factors, permeate the rust layer and reach the ground iron. To prevent. Moreover, an anode reaction is suppressed on the steel material surface.
(4) And, in order to maximize the corrosion resistance improvement effect, it is important to actively use Si among the above elements, and this Si content is adjusted to an appropriate range to obtain Cu. By adding a small amount of each of elements such as Ni, Sn, Sb, and adding W and further adding W, the effect of improving the corrosion resistance of each element can be obtained synergistically, and a large amount of elements such as Cu, Ni, Sn, Sb can be obtained. Even if it is not contained, the corrosion resistance, particularly the coating durability, is greatly improved.
The present invention has been completed through further studies based on the above findings.
すなわち、本発明の要旨構成は次のとおりである。 That is, the gist configuration of the present invention is as follows.
１．質量％で、
Ｃ：０．０２０％以上、０．２００％以下、
Ｓｉ：０．０５％以上、１．００％以下、
Ｍｎ：０．２０％以上、２．００％以下、
Ｐ：０．００３％以上、０．０３０％以下、
Ｓ：０．０００１％以上、０．０１００％以下、
Ａｌ：０．００１％以上、０．１００％以下、
Ｃｕ：０．０１％以上、０．５０％以下、
Ｎｉ：０．０１％以上、０．５０％以下および
Ｗ：０．００５％以上、１．０００％以下
を含有するとともに、
Ｓｎ：０．００５％以上、０．２００％以下および
Ｓｂ：０．００５％以上、０．２００％以下
のうちから選ばれる１種または２種を含有し、
残部がＦｅおよび不可避的不純物からなる成分組成を有することを特徴とする塗装耐久性に優れた構造用鋼材。
1. % By mass
C: 0.020% or more, 0.200% or less,
Si: 0.05% or more and 1.00% or less,
Mn: 0.20% or more, 2.00% or less,
P: 0.003% or more, 0.030% or less,
S: 0.0001% or more, 0.0100% or less,
Al: 0.001% or more, 0.100% or less,
Cu: 0.01% or more, 0.50% or less,
Ni: 0.01% or more and 0.50% or less and W: 0.005% or more and 1.000% or less,
Sn: 0.005% or more, 0.200% or less and Sb: 0.005% or more, 0.200% or less, one or two selected from,
A structural steel material excellent in coating durability, characterized in that the balance has a component composition comprising Fe and inevitable impurities.
２．前記成分組成におけるＳｉの含有量が、０．４０％以上、０．６０％以下であることを特徴とする前記１に記載の塗装耐久性に優れた構造用鋼材。 2. 2. The structural steel material having excellent coating durability according to 1 above, wherein the Si content in the component composition is 0.40% or more and 0.60% or less.
３．前記成分組成が、さらに、質量％で、
Ｍｏ：０．００５％以上、０．５００％以下
を含有することを特徴とする前記１または２に記載の塗装耐久性に優れた構造用鋼材。
3. The component composition is further in mass%,
Mo: 0.005% or more and 0.500% or less is contained, The structural steel material excellent in coating durability of said 1 or 2 characterized by the above-mentioned.
４．前記成分組成が、さらに、質量％で、
Ｖ：０．００５％以上、０．２００％以下、
Ｔｉ：０．００５％以上、０．０５０％以下および
Ｚｒ：０．００５％以上、０．１００％以下
のうちからから選ばれる１種または２種以上を含有することを特徴とする前記１乃至３のいずれかに記載の塗装耐久性に優れた構造用鋼材。
4). The component composition is further in mass%,
V: 0.005% or more, 0.200% or less,
Ti: 0.005% or more and 0.050% or less and Zr: 0.005% or more and 0.100% or less, containing one or more selected from the above 1 to 2 3. A structural steel material having excellent paint durability according to any one of 3 above.
５．前記成分組成が、さらに、質量％で、
Ｂ：０．０００１％以上、０．００５０％以下
を含有することを特徴とする前記１乃至４のいずれかに記載の塗装耐久性に優れた構造用鋼材。
5. The component composition is further in mass%,
B: The structural steel material having excellent coating durability according to any one of 1 to 4 above, containing 0.0001% or more and 0.0050% or less.
６．前記成分組成が、さらに、質量％で、
Ｃａ：０．０００１％以上、０．０１００％以下および
Ｍｇ：０．０００１％以上、０．０１００％以下、
のうちから選ばれる１種または２種を含有することを特徴とする前記１乃至５のいずれかに記載の塗装耐久性に優れた構造用鋼材。
6). The component composition is further in mass%,
Ca: 0.0001% to 0.0100% and Mg: 0.0001% to 0.0100%,
The structural steel material having excellent coating durability according to any one of 1 to 5 above, wherein the structural steel material contains one or two selected from the above.
７．前記１乃至６のいずれかに記載の塗装耐久性に優れた構造用鋼材であって、その表面に塗膜を有することを特徴とする塗装耐久性に優れた構造用鋼材。 7). 7. A structural steel material having excellent coating durability according to any one of 1 to 6, which has a coating film on the surface thereof.
８．前記塗膜が、防食下地層、下塗り層、中塗り層および上塗り層を有し、
該防食下地層が無機ジンクリッチペイント、該下塗り層がエポキシ樹脂塗料、該中塗り層がふっ素樹脂上塗り塗料用の中塗り塗料、該上塗り層がふっ素樹脂上塗り塗料をそれぞれ用いてなることを特徴とする前記７に記載の塗装耐久性に優れた構造用鋼材。
8). The coating film has an anticorrosion underlayer, an undercoat layer, an intermediate coat layer and an overcoat layer,
The anticorrosion underlayer is composed of an inorganic zinc rich paint, the undercoat layer is an epoxy resin paint, the intermediate coat layer is an intermediate coat for a fluororesin overcoat, and the overcoat layer is a fluororesin overcoat. The structural steel material excellent in coating durability as described in 7 above.
９．前記１乃至８のいずれかに記載の塗装耐久性に優れた構造用鋼材を有することを特徴とする構造物。 9. 9. A structure comprising the structural steel material having excellent paint durability according to any one of 1 to 8 above.
１０．橋梁であることを特徴とする前記９に記載の構造物。 10. 10. The structure according to 9 above, which is a bridge.
本発明によれば、橋梁などの屋外の大気腐食環境下、特には飛来塩分量の多い海上や海岸近傍などの厳しい腐食環境下で使用する場合であっても、塗り替え周期を延長して塗装頻度を低減することが可能な塗装耐久性に優れた構造用鋼材を、低コストに得ることができる。
そして、本発明の塗装耐久性に優れた構造用鋼材を、橋梁などの屋外の大気腐食環境下、特には飛来塩分量の多い海上や海岸近傍などの厳しい腐食環境下で使用される橋梁などの構造物に好適に用いることにより、かような構造物のメンテナンスコスト、ひいてはライフサイクルコストを低減することが可能となる。
According to the present invention, even when used in an outdoor atmospheric corrosive environment such as a bridge, particularly in a severe corrosive environment such as the sea or near the coast where there is a large amount of incoming salt, the paint frequency is extended to increase the painting frequency. It is possible to obtain a structural steel material excellent in coating durability capable of reducing the cost at low cost.
The structural steel material with excellent paint durability of the present invention is used in outdoor atmospheric corrosive environments such as bridges, especially in bridges used in severe corrosive environments such as the sea and the coastal areas where the amount of incoming salt is high. By suitably using the structure, it is possible to reduce the maintenance cost of such a structure, and consequently the life cycle cost.
以下、本発明を具体的に説明する。まず、本発明において鋼の成分組成を前記の範囲に限定した理由について説明する。なお、鋼の成分組成における元素の含有量の単位はいずれも「質量％」であるが、以下、特に断らない限り単に「％」で示す。 Hereinafter, the present invention will be specifically described. First, the reason why the composition of steel is limited to the above range in the present invention will be described. In addition, although the unit of element content in the component composition of steel is “mass%”, hereinafter, it is simply indicated by “%” unless otherwise specified.
Ｃ：０．０２０％以上、０．２００％以下
Ｃは、鋼材の強度を上昇させる元素である。このため、Ｃは、構造用鋼としての所定の強度を確保するため、０．０２０％以上含有させる必要がある。一方、Ｃ含有量が０．２００％を超えると、溶接性および靭性が劣化する。したがって、Ｃ含有量は０．０２０％以上、０．２００％以下とする。
C: 0.020% to 0.200% C is an element that increases the strength of the steel material. For this reason, in order to ensure the predetermined intensity | strength as structural steel, it is necessary to contain C 0.020% or more. On the other hand, when the C content exceeds 0.200%, weldability and toughness deteriorate. Therefore, the C content is set to 0.020% or more and 0.200% or less.
Ｓｉ：０．０５％以上、１．００％以下
Ｓｉは、本発明の塗装耐久性に優れた構造用鋼材において重要な元素であり、さび層全体のさび粒を微細化して緻密なさび層を形成し、鋼材の塗装耐久性を向上させる効果を有する。また、Ｓｉは製鋼時の脱酸に必要な元素である。これらの効果を得るため、Ｓｉは０．０５％以上含有させる必要がある。一方、Ｓｉ含有量が１．００％を超えると、靭性および溶接性が著しく劣化する。したがって、Ｓｉ含有量は０．０５％以上、１．００％以下とする。好ましくは０．１５％以上、０．８０％以下である。また、塗装耐久性を一層向上させる観点からは、Ｓｉ含有量は０．４０％以上、０．６０％以下とすることがより好ましい。
Si: 0.05% or more and 1.00% or less Si is an important element in the structural steel material excellent in coating durability of the present invention, and a fine rust layer is formed by refining the rust grains of the entire rust layer. It has the effect of forming and improving the coating durability of steel. Si is an element necessary for deoxidation during steelmaking. In order to acquire these effects, it is necessary to contain Si 0.05% or more. On the other hand, when the Si content exceeds 1.00%, the toughness and weldability are significantly deteriorated. Therefore, the Si content is 0.05% or more and 1.00% or less. Preferably they are 0.15% or more and 0.80% or less. Further, from the viewpoint of further improving the coating durability, the Si content is more preferably 0.40% or more and 0.60% or less.
Ｍｎ：０．２０％以上、２．００％以下
Ｍｎは、鋼材の強度を上昇させる元素である。このため、Ｍｎは、構造用鋼としての所定の強度を確保するため、０．２０％以上含有させる必要がある。一方、Ｍｎ含有量が２．００％を超えると、靭性および溶接性が劣化する。したがって、Ｍｎ含有量は０．２０％以上、２．００％以下とする。好ましくは０．７５％以上、１．８０％以下である。
Mn: 0.20% or more and 2.00% or less Mn is an element that increases the strength of the steel material. For this reason, Mn needs to be contained by 0.20% or more in order to ensure a predetermined strength as structural steel. On the other hand, if the Mn content exceeds 2.00%, the toughness and weldability deteriorate. Therefore, the Mn content is 0.20% or more and 2.00% or less. Preferably they are 0.75% or more and 1.80% or less.
Ｐ：０．００３％以上、０．０３０％以下
Ｐは、鋼材の塗装耐久性の向上に寄与する元素である。このような効果を得る観点から、Ｐは０．００３％以上含有させる必要がある。一方、Ｐ含有量が０．０３０％を超えると、溶接性が劣化する。したがって、Ｐ含有量は０．００３％以上、０．０３０％以下とする。
P: 0.003% or more and 0.030% or less P is an element that contributes to improving the coating durability of steel. From the viewpoint of obtaining such an effect, P needs to be contained by 0.003% or more. On the other hand, if the P content exceeds 0.030%, the weldability deteriorates. Therefore, the P content is set to 0.003% or more and 0.030% or less.
Ｓ：０．０００１％以上、０．０１００％以下
Ｓは、溶接性および靭性を劣化させる元素である。このため、Ｓ含有量は０．０１００％以下とする必要がある。ただし、Ｓ含有量を０．０００１％未満にしようとすると、生産コストが増大する。したがって、Ｓ含有量は０．０００１％以上、０．０１００％以下とする。
S: 0.0001% to 0.0100% S is an element that deteriorates weldability and toughness. For this reason, S content needs to be 0.0100% or less. However, if the S content is less than 0.0001%, the production cost increases. Therefore, the S content is set to 0.0001% or more and 0.0100% or less.
Ａｌ：０．００１％以上、０．１００％以下
Ａｌは、製鋼時の脱酸に必要な元素である。このような効果を得るため、Ａｌは０．００１％以上含有させる必要がある。一方、Ａｌ含有量が０．１００％を超えると、溶接性に悪影響を及ぼす。したがって、Ａｌ含有量は０．００１％以上、０．１００％以下とする。好ましくは、０．００５％以上、０．０５０％未満とする。より好ましくは、０．０１０％以上、０．０３０％未満とする。
Al: 0.001% or more and 0.100% or less Al is an element necessary for deoxidation during steelmaking. In order to acquire such an effect, it is necessary to contain Al 0.001% or more. On the other hand, if the Al content exceeds 0.100%, the weldability is adversely affected. Therefore, the Al content is set to 0.001% or more and 0.100% or less. Preferably, the content is 0.005% or more and less than 0.050%. More preferably, it is 0.010% or more and less than 0.030%.
Ｃｕ：０．０１％以上、０．５０％以下
Ｃｕは、本発明の塗装耐久性に優れた構造用鋼材において重要な元素であり、さび層のさび粒を微細化することで緻密なさび層を形成し、腐食促進因子である酸素や塩化物イオンの地鉄への透過を抑制する効果を有する。そして、Ｃｕは、Ｓｉ量を適正な範囲に調整した上で、ＮｉやＳｎ、Ｓｂ、さらにはＷとともに複合添加することで、これらの元素との相乗効果によって、鋼材の塗装耐久性を大きく向上させる。このような効果は、Ｃｕ含有量が０．０１％以上で得られる。一方、Ｃｕ含有量が０．５０％を超えると、合金コストの上昇を招く。したがって、Ｃｕ含有量は０．０１％以上、０．５０％以下とする。好ましくは、０．０３％以上、０．４０％以下、より好ましくは、０．０４％以上、０．３０％以下である。さらに好ましくは０．０５％以上、０．２５％以下である。
Cu: 0.01% or more and 0.50% or less Cu is an important element in the structural steel material excellent in coating durability of the present invention, and a fine rust layer is obtained by refining the rust grains of the rust layer. And has the effect of suppressing the penetration of oxygen and chloride ions, which are corrosion promoting factors, into the ground iron. And Cu, after adjusting the amount of Si to an appropriate range, by adding together with Ni, Sn, Sb, and W, synergistic effects with these elements greatly improve the coating durability of steel materials Let Such an effect is obtained when the Cu content is 0.01% or more. On the other hand, if the Cu content exceeds 0.50%, the alloy cost increases. Therefore, the Cu content is set to 0.01% or more and 0.50% or less. Preferably, it is 0.03% or more and 0.40% or less, more preferably 0.04% or more and 0.30% or less. More preferably, it is 0.05% or more and 0.25% or less.
Ｎｉ：０．０１％以上、０．５０％以下
Ｎｉは、さび層のさび粒を微細化することで緻密なさび層を形成し、腐食促進因子である酸素や塩化物イオンの地鉄への透過を抑制する効果を有する。そして、Ｎｉは、Ｓｉ量を適正な範囲に調整した上で、ＣｕやＳｎ、Ｓｂ、さらにはＷとともに複合添加することで、これらの元素との相乗効果によって、鋼材の塗装耐久性を大きく向上させる。このような効果は、Ｎｉ含有量が０．０１％以上で得られる。一方、Ｎｉ含有量が０．５０％を超えると、合金コストの上昇を招く。したがって、Ｎｉ含有量は０．０１％以上、０．５０％以下とする。好ましくは、０．０３％以上、０．４０％未満、より好ましくは、０．０４％以上、０．３０％以下である。さらに好ましくは、０．０５％以上、０．１５％以下である。
Ni: 0.01% or more and 0.50% or less Ni forms a dense rust layer by refining the rust grains of the rust layer, and oxygen and chloride ions, which are corrosion promoting factors, are applied to the ground iron. It has the effect of suppressing transmission. And, Ni adjusts the amount of Si to an appropriate range, and by adding it together with Cu, Sn, Sb, and W, synergistic effects with these elements greatly improve the coating durability of steel materials Let Such an effect is obtained when the Ni content is 0.01% or more. On the other hand, if the Ni content exceeds 0.50%, the alloy cost increases. Therefore, the Ni content is 0.01% or more and 0.50% or less. Preferably, it is 0.03% or more and less than 0.40%, more preferably 0.04% or more and 0.30% or less. More preferably, it is 0.05% or more and 0.15% or less.
Ｗ：０．００５％以上、１．０００％以下
Ｗは鋼材のアノード反応に伴って溶出し、さび層中にＷＯ４ ２−として分布することによって、腐食促進因子の塩化物イオンがさび層を透過して地鉄に到達するのを静電的に防止する。さらに、鋼材表面にＷを含む化合物が沈殿することで、鋼材のアノード反応を抑制する。そして、Ｗは、Ｓｉ量を適正な範囲に調整した上で、ＣｕやＮｉ、Ｓｎ、Ｓｂとともに複合添加することで、これらの元素との相乗効果によって、鋼材の塗装耐久性を大きく向上させる。このような効果を十分に得るためには、Ｗを０．００５％以上含有させる必要がある。一方、Ｗ含有量が１．０００％を超えると、合金コスト上昇を招く。したがって、Ｗ含有量は０．００５％以上、１．０００％以下とする。好ましくは、０．０１０％以上、０．７００％以下、より好ましくは、０．０３０％以上０．５００％以下である。さらに好ましくは０．０５％以上、０．３０％以下である。
W: 0.005% or more, 1.000% or less W is eluted with the anode reaction of the steel material, and is distributed as WO 4 2− in the rust layer. Electrostatically prevent penetration and reaching the ground. Further, the precipitation of a compound containing W on the steel material surface suppresses the anode reaction of the steel material. And W adjusts the amount of Si to an appropriate range, and by adding it together with Cu, Ni, Sn, and Sb, the coating durability of the steel material is greatly improved by a synergistic effect with these elements. In order to sufficiently obtain such an effect, it is necessary to contain 0.005% or more of W. On the other hand, if the W content exceeds 1.000%, the alloy cost increases. Therefore, the W content is set to 0.005% or more and 1.000% or less. Preferably, they are 0.010% or more and 0.700% or less, More preferably, they are 0.030% or more and 0.500% or less. More preferably, it is 0.05% or more and 0.30% or less.
また、本発明の塗装耐久性に優れた構造用鋼材では、Ｓｎ：０．００５％以上、０．２００％以下およびＳｂ：０．００５％以上、０．２００％以下のうちから選ばれる１種または２種を含有させる。
Ｓｎ：０．００５％以上、０．２００％以下
Ｓｎは、地鉄表面近傍においてさび層中に存在し、さび粒子を微細化することで腐食促進因子である塩化物イオンがさび層を透過して地鉄に到達するのを防止する。また、Ｓｎは、鋼材表面においてアノード反応を抑制する。そして、Ｓｎは、Ｓｉ量を適正な範囲に調整した上で、ＣｕやＮｉ、Ｓｂ、さらにはＷとともに複合添加することで、これらの元素との相乗効果によって、鋼材の塗装耐久性を大きく向上させる。このような効果を十分に得るためには、Ｓｎを０．００５％以上含有させる必要がある。一方、Ｓｎ含有量が０．２００％を超えると、鋼の延性や靭性の劣化を招く。したがって、Ｓｎ含有量は、０．００５％以上、０．２００％以下とする。好ましくは、０．０１０％以上、０．１００％以下である。より好ましくは、０．０２０％以上、０．０５０％未満である。
Further, in the structural steel material excellent in coating durability according to the present invention, Sn: 0.005% or more and 0.200% or less and Sb: 0.005% or more and 0.200% or less, one kind selected from Or 2 types are contained.
Sn: 0.005% or more and 0.200% or less Sn exists in the rust layer in the vicinity of the surface of the iron base, and chloride ions, which are corrosion promoting factors, permeate the rust layer by refining rust particles. To prevent it from reaching the railway. Further, Sn suppresses the anode reaction on the steel material surface. And Sn, after adjusting the amount of Si to an appropriate range, by adding together with Cu, Ni, Sb, and W, synergistic effects with these elements greatly improve the coating durability of steel materials Let In order to obtain such effects sufficiently, it is necessary to contain 0.005% or more of Sn. On the other hand, if the Sn content exceeds 0.200%, the ductility and toughness of the steel are deteriorated. Therefore, the Sn content is set to be 0.005% or more and 0.200% or less. Preferably, it is 0.010% or more and 0.100% or less. More preferably, it is 0.020% or more and less than 0.050%.
Ｓｂ：０．００５％以上、０．２００％以下
Ｓｂは、地鉄表面近傍においてさび層中に存在し、さび粒子を微細化することで腐食促進因子である塩化物イオンがさび層を透過して地鉄に到達するのを防止する。また、Ｓｂは、鋼材表面においてアノード反応を抑制する。そして、Ｓｂは、Ｓｉ量を適正な範囲に調整した上で、ＣｕやＮｉ、Ｓｎ、さらにはＷとともに複合添加することで、これらの元素との相乗効果によって、鋼材の塗装耐久性を大きく向上させる。このような効果を十分に得るためには、Ｓｂを０．００５％以上含有させる必要がある。一方、Ｓｂ含有量が０．２００％を超えると、鋼の延性や靭性の劣化を招く。したがって、Ｓｂ含有量は０．００５％以上、０．２００％以下とする。好ましくは、０．０１０％以上、０．１５０％以下、より好ましくは、０．０２０％以上、０．１００％以下である。
Sb: 0.005% or more and 0.200% or less Sb is present in the rust layer in the vicinity of the surface of the iron base, and chloride ions, which are corrosion accelerating factors, permeate the rust layer by refining rust particles. To prevent it from reaching the railway. Moreover, Sb suppresses an anode reaction on the steel material surface. And Sb, after adjusting the amount of Si to an appropriate range, by adding together with Cu, Ni, Sn, and W, synergistic effects with these elements greatly improve the coating durability of steel materials Let In order to obtain such an effect sufficiently, it is necessary to contain 0.005% or more of Sb. On the other hand, when the Sb content exceeds 0.200%, the ductility and toughness of the steel are deteriorated. Therefore, the Sb content is 0.005% or more and 0.200% or less. Preferably, they are 0.010% or more and 0.150% or less, More preferably, they are 0.020% or more and 0.100% or less.
以上、基本成分について説明したが、本発明では、必要に応じて、以下に述べる元素を適宜含有させることができる。 The basic components have been described above. In the present invention, the following elements can be appropriately contained as necessary.
Ｍｏ：０．００５％以上、０．５００％以下
Ｍｏは、鋼材のアノード反応に伴って溶出し、さび層中にＭｏＯ４ ２−が分布することで、腐食促進因子である塩化物イオンがさび層を透過して地鉄に到達するのを防止する。また、鋼材表面にＭｏを含む化合物が沈殿することで、鋼材のアノード反応を抑制する。このような効果を十分に得るためには、Ｍｏを０．００５％以上含有させることが好適である。一方、Ｍｏ含有量が０．５００％を超えると、合金コストの上昇を招く。したがって、Ｍｏを含有する場合、Ｍｏ含有量は０．００５％以上０．５００％以下とする。
Mo: 0.005% or more and 0.500% or less Mo is eluted with the anode reaction of the steel material, and MoO 4 2− is distributed in the rust layer, so that chloride ions which are corrosion promoting factors are rusted. Prevents the penetration of the layer to reach the railway. Moreover, the anode reaction of steel materials is suppressed because the compound containing Mo precipitates on the steel material surface. In order to obtain such an effect sufficiently, it is preferable to contain 0.005% or more of Mo. On the other hand, if the Mo content exceeds 0.500%, the alloy cost increases. Therefore, when it contains Mo, Mo content shall be 0.005% or more and 0.500% or less.
Ｖ：０．００５％以上、０．２００％以下
Ｖは、強度を高める元素である。このような効果を十分に得るためには、Ｖを０．００５％以上含有させることが好適である。一方、Ｖ含有量が０．２００％を超えると、その強度向上効果が飽和する。したがって、Ｖを含有する場合、Ｖ含有量は０．００５％以上、０．２００％以下とする。
V: 0.005% to 0.200% V is an element that increases the strength. In order to sufficiently obtain such an effect, it is preferable to contain V by 0.005% or more. On the other hand, if the V content exceeds 0.200%, the strength improvement effect is saturated. Therefore, when V is contained, the V content is set to 0.005% or more and 0.200% or less.
Ｔｉ：０．００５％以上、０．０５０％以下
Ｔｉは、強度を高める元素である。このような効果を十分に得るためには、Ｔｉを０．００５％以上含有させることが好適である。一方、Ｔｉ含有量が０．０５０％を超えると、靭性の劣化を招く。したがって、Ｔｉを含有する場合、Ｔｉ含有量は０．００５％以上、０．０５０％以下とする。
Ti: 0.005% or more and 0.050% or less Ti is an element that increases the strength. In order to sufficiently obtain such an effect, it is preferable to contain 0.005% or more of Ti. On the other hand, if the Ti content exceeds 0.050%, the toughness is deteriorated. Therefore, when Ti is contained, the Ti content is set to 0.005% or more and 0.050% or less.
Ｚｒ：０．００５％以上、０．１００％以下
Ｚｒは、強度を高める元素である。このような効果を十分に得るためには、Ｚｒを０．００５％以上含有させることが好適である。一方、Ｚｒ含有量が０．１００％を超えると、その強度向上効果が飽和する。したがって、Ｚｒを含有する場合、Ｚｒ含有量は０．００５％以上、０．１００％以下とする。
Zr: 0.005% or more and 0.100% or less Zr is an element that increases the strength. In order to sufficiently obtain such an effect, it is preferable to contain 0.005% or more of Zr. On the other hand, when the Zr content exceeds 0.100%, the strength improvement effect is saturated. Therefore, when Zr is contained, the Zr content is set to 0.005% or more and 0.100% or less.
Ｂ：０．０００１％以上、０．００５０％以下
Ｂは、強度を高める元素である。このような効果を十分に得るためには、Ｂを０．０００１％以上含有させることが好適である。一方、Ｂ含有量が０．００５０％を超えると、靭性の劣化を招く。したがって、Ｂを含有する場合、Ｂ含有量は０．０００１％以上、０．００５０％以下とする。
B: 0.0001% or more and 0.0050% or less B is an element that increases the strength. In order to sufficiently obtain such an effect, it is preferable to contain 0.0001% or more of B. On the other hand, if the B content exceeds 0.0050%, the toughness is deteriorated. Therefore, when it contains B, B content shall be 0.0001% or more and 0.0050% or less.
Ｃａ：０．０００１％以上、０．０１００％以下
Ｃａは、鋼中のＳを固定し、溶接熱影響部の靭性を向上させる元素である。このような効果を十分に得るためには、Ｃａを０．０００１％以上含有させることが好適である．一方、Ｃａ含有量が０．０１００％を超えると、鋼中の介在物の量が増加し、かえって靭性の劣化を招く。したがって、Ｃａを含有する場合、Ｃａ含有量は０．０００１％以上、０．０１００％以下とする。
Ca: 0.0001% or more and 0.0100% or less Ca is an element that fixes S in steel and improves the toughness of the weld heat affected zone. In order to sufficiently obtain such an effect, it is preferable to contain 0.0001% or more of Ca. On the other hand, if the Ca content exceeds 0.0100%, the amount of inclusions in the steel increases, which leads to deterioration of toughness. Therefore, when it contains Ca, Ca content shall be 0.0001% or more and 0.0100% or less.
Ｍｇ：０．０００１％以上、０．０１００％以下
Ｍｇは、鋼中のＳを固定し、溶接熱影響部の靭性を向上させる元素である。このような効果を十分に得るためには、Ｍｇを０．０００１％以上含有させることが好適である。一方、Ｍｇ含有量が０．０１００％を超えると、鋼中の介在物の量が増加し、かえって靭性の劣化を招く。したがって、Ｍｇを含有する場合、Ｍｇ含有量は０．０００１％以上、０．０１００％以下とする。
Mg: 0.0001% or more and 0.0100% or less Mg is an element that fixes S in steel and improves the toughness of the heat affected zone. In order to sufficiently obtain such an effect, it is preferable to contain Mg in an amount of 0.0001% or more. On the other hand, if the Mg content exceeds 0.0100%, the amount of inclusions in the steel increases, which leads to deterioration of toughness. Therefore, when it contains Mg, Mg content shall be 0.0001% or more and 0.0100% or less.
上記以外の成分は、Ｆｅおよび不可避的不純物である。なお、不可避的不純物としては、ＮやＯ（酸素）が挙げられ、Ｎ：０．０１０％以下、Ｏ：０．０１０％以下であれば許容できる。 Components other than the above are Fe and inevitable impurities. Inevitable impurities include N and O (oxygen), and N: 0.010% or less and O: 0.010% or less are acceptable.
また、本発明の鋼材は、通常、鋼材表面を塗装して使用される。ここで、鋼材表面の塗膜としては、例えば、防食下地層、下塗り層、中塗り層および上塗り層をこの順に有する塗膜が挙げられる。
なお、防食下地層は無機ジンクリッチペイント（例えば、ＳＤジンク１５００）、下塗り層はエポキシ樹脂塗料（例えば、エポマリンHB(K)）、中塗り層はふっ素樹脂上塗り塗料用の中塗り塗料（例えば、セラテクトF中塗）、上塗り層はふっ素樹脂上塗り塗料（例えば、セラテクトF(K)上塗）を用いて形成することが好ましい。
Further, the steel material of the present invention is usually used by coating the steel material surface. Here, as a coating film on the steel material surface, for example, a coating film having an anticorrosion underlayer, an undercoat layer, an intermediate coat layer, and an overcoat layer in this order can be mentioned.
The anticorrosion undercoat layer is an inorganic zinc rich paint (for example, SD zinc 1500), the undercoat layer is an epoxy resin paint (for example, Epomarin HB (K)), and the intermediate coat layer is an intermediate paint for a fluororesin overcoat (for example, It is preferable that the overcoat layer is formed using a fluororesin overcoat (for example, the overcoat F (K)).
さらに、本発明の塗装耐久性に優れた構造用鋼材は、上記の成分組成を有する鋼を溶製し、通常の連続鋳造法や分塊法によりスラブ等の鋼素材とし、得られた鋼素材を熱間圧延などの熱間加工により、厚板や形鋼、薄鋼板、棒鋼等の鋼材とすることで、製造することができる。
鋼スラブの加熱条件や熱間圧延条件は特に限定されず、要求される特性などに応じて適宜決定すればよい。なお、制御圧延や加速冷却、再加熱熱処理等の組合せも可能である。
また、鋼における各元素の含有量は、スパーク放電発光分光分析法、蛍光Ｘ線分析法、ＩＣＰ発光分光分析法、ＩＣＰ質量分析法または燃焼法等により求めることができる。
Furthermore, the structural steel material excellent in coating durability of the present invention is a steel material obtained by melting a steel having the above-described composition and making it a steel material such as a slab by a normal continuous casting method or a block method. Can be manufactured by using a steel material such as a thick plate, a shape steel, a thin steel plate, or a steel bar by hot working such as hot rolling.
The heating conditions and hot rolling conditions of the steel slab are not particularly limited, and may be appropriately determined according to required characteristics. Combinations such as controlled rolling, accelerated cooling, and reheating heat treatment are also possible.
The content of each element in the steel can be determined by spark discharge emission spectrometry, fluorescent X-ray analysis, ICP emission spectroscopy, ICP mass spectrometry, combustion method, or the like.
表１に示す成分組成になる鋼（残部はＦｅおよび不可避的不純物である）を溶製し、１１５０℃に加熱して熱間圧延を施し、空冷後、板厚：１２ｍｍの鋼板を得た。
そして、以下の要領にて、塗装耐久性の評価を実施した。
Steel having the composition shown in Table 1 (the balance is Fe and inevitable impurities) was melted, heated to 1150 ° C. and hot-rolled, and after air cooling, a steel plate having a thickness of 12 mm was obtained.
And the coating durability was evaluated in the following manner.
・塗装耐久性の評価
上記のようにして得た鋼板から７０ｍｍ×５０ｍｍ×５ｍｍの試験片を採取した。この試験片の表面に、表面粗さがＩＳＯ Ｓａ ２．５となるようショットブラストを施し、アセトン中での超音波脱脂を５分間行い、風乾した。ついで、試験片の片面を塗装面とし、防食下地として無期ジンクリッチペイント（厚さ：７５μｍ）を塗布し、ついで下塗りとしてエポキシ樹脂塗料（厚さ：１２０μｍ）を塗布し、ついで中塗りとしてふっ素樹脂上塗り塗料用の中塗り塗料（厚さ：３０μｍ）を塗布し、ついで上塗りとしてふっ素樹脂塗料上塗り塗料（厚さ：２５μｍ）を塗布し、防食下地層、下塗り層、中塗り層および上塗り層からなる塗膜を形成した。なお、試験片の他方の片面と端面は、溶剤型のエポキシ樹脂塗料にてシールし、さらにシリコン系のシール剤にて被覆した。
-Evaluation of coating durability A test piece of 70 mm x 50 mm x 5 mm was collected from the steel plate obtained as described above. The surface of this test piece was shot blasted so that the surface roughness was ISO Sa 2.5, ultrasonic degreasing in acetone was performed for 5 minutes, and air-dried. Next, one side of the test piece is used as the coating surface, indefinite zinc rich paint (thickness: 75 μm) is applied as the anticorrosion base, and then an epoxy resin paint (thickness: 120 μm) is applied as the undercoat, followed by fluorine resin as the intermediate coating. Apply an intermediate coating (thickness: 30 μm) for top coating, then apply a fluororesin coating top coating (thickness: 25 μm) as the top coating, and consist of an anticorrosion undercoat layer, undercoat layer, intermediate coating layer and top coating layer A coating film was formed. The other side and end surface of the test piece were sealed with a solvent-type epoxy resin paint and further covered with a silicon-based sealant.
塗装後、試験片に形成した塗膜の中央部に、地鉄に到達するように幅：１ｍｍ、長さ：４０ｍｍの直線のカットを入れ、初期欠陥を設けた。ついで、以下に示す条件にて腐食試験を実施した。
すなわち、試験片表面の人工海塩の付着量が６．０ｇ／ｍ２となるように、人工海塩を純水で所定の濃度に希釈した溶液をスプレーし、試験片に人工海塩を付着させた。ついで、この試験片を用いて、（条件１．温度：６０℃、相対湿度：３５％、保持時間：３時間）、（条件２．温度：４０度、相対湿度：９５％、保持時間：３時間）、条件１から条件２および条件２から条件１への各移行時間を１時間とする、合計８時間のサイクルを１サイクルとして、これを１２００サイクル繰り返す腐食試験を実施した。なお、人工海塩の付着は、週に１回とした。
そして、腐食試験終了後、塗装における初期欠陥部からの膨れ面積（塗装膨れ面積）を測定し、塗装耐久性を評価した。結果を表２に示す。なお、塗装膨れ面積が４８０ｍｍ２以下であれば、塗装の耐久性に優れると判断した。
After painting, a straight cut with a width of 1 mm and a length of 40 mm was made at the center of the coating film formed on the test piece so as to reach the base iron, thereby providing an initial defect. Next, a corrosion test was performed under the following conditions.
That is, a solution obtained by diluting artificial sea salt to a predetermined concentration with pure water is sprayed so that the adhesion amount of artificial sea salt on the surface of the test piece is 6.0 g / m 2, and the artificial sea salt is attached to the test piece. I let you. Then, using this test piece, (Condition 1. Temperature: 60 ° C., Relative humidity: 35%, Holding time: 3 hours), (Condition 2. Temperature: 40 degrees, Relative humidity: 95%, Holding time: 3 Time), each transition time from condition 1 to condition 2 and from condition 2 to condition 1 was set to 1 hour. A total of 8 hours was defined as 1 cycle, and a corrosion test was repeated 1200 times. The artificial sea salt was attached once a week.
And after completion | finish of a corrosion test, the swelling area (paint swelling area) from the initial stage defect part in coating was measured, and coating durability was evaluated. The results are shown in Table 2. In addition, if the paint swelling area was 480 mm 2 or less, it was judged that the durability of the paint was excellent.
表２より、発明例ではいずれも塗装の膨れ面積が４８０ｍｍ２以下であり、塗装耐久性に優れることがわかる。
一方、比較例では、塗装の膨れ面積が４８０ｍｍ２を超えており、十分な塗装耐久性が得られなかった。
From Table 2, it can be seen that in the invention examples, the swollen area of the coating is 480 mm 2 or less, and the coating durability is excellent.
On the other hand, in the comparative example, the swollen area of the coating exceeded 480 mm 2 , and sufficient coating durability was not obtained.
Claims (10)
Ｃ：０．０２０％以上、０．２００％以下、
Ｓｉ：０．０５％以上、１．００％以下、
Ｍｎ：０．２０％以上、２．００％以下、
Ｐ：０．００３％以上、０．０３０％以下、
Ｓ：０．０００１％以上、０．０１００％以下、
Ａｌ：０．００１％以上、０．１００％以下、
Ｃｕ：０．０１％以上、０．５０％以下、
Ｎｉ：０．０１％以上、０．５０％以下および
Ｗ：０．００５％以上、１．０００％以下
を含有するとともに、
Ｓｎ：０．００５％以上、０．２００％以下および
Ｓｂ：０．００５％以上、０．２００％以下
のうちから選ばれる１種または２種を含有し、
残部がＦｅおよび不可避的不純物からなる成分組成を有することを特徴とする塗装耐久性に優れた構造用鋼材。 % By mass
C: 0.020% or more, 0.200% or less,
Si: 0.05% or more and 1.00% or less,
Mn: 0.20% or more, 2.00% or less,
P: 0.003% or more, 0.030% or less,
S: 0.0001% or more, 0.0100% or less,
Al: 0.001% or more, 0.100% or less,
Cu: 0.01% or more, 0.50% or less,
Ni: 0.01% or more and 0.50% or less and W: 0.005% or more and 1.000% or less,
Sn: 0.005% or more, 0.200% or less and Sb: 0.005% or more, 0.200% or less, one or two selected from,
A structural steel material excellent in coating durability, characterized in that the balance has a component composition comprising Fe and inevitable impurities.
Ｍｏ：０．００５％以上、０．５００％以下
を含有することを特徴とする請求項１または２に記載の塗装耐久性に優れた構造用鋼材。 The component composition is further in mass%,
Mo: 0.005% or more and 0.500% or less are contained, The structural steel material excellent in coating durability of Claim 1 or 2 characterized by the above-mentioned.
Ｖ：０．００５％以上、０．２００％以下、
Ｔｉ：０．００５％以上、０．０５０％以下および
Ｚｒ：０．００５％以上、０．１００％以下
のうちからから選ばれる１種または２種以上を含有することを特徴とする請求項１乃至３のいずれか一項に記載の塗装耐久性に優れた構造用鋼材。 The component composition is further in mass%,
V: 0.005% or more, 0.200% or less,
2. One or more selected from Ti: 0.005% or more and 0.050% or less and Zr: 0.005% or more and 0.100% or less. The structural steel material excellent in the coating durability as described in any one of thru | or 3.
Ｂ：０．０００１％以上、０．００５０％以下
を含有することを特徴とする請求項１乃至４のいずれか一項に記載の塗装耐久性に優れた構造用鋼材。 The component composition is further in mass%,
B: 0.0001% or more and 0.0050% or less is contained, The structural steel material excellent in coating durability as described in any one of Claims 1 thru | or 4 characterized by the above-mentioned.
Ｃａ：０．０００１％以上、０．０１００％以下および
Ｍｇ：０．０００１％以上、０．０１００％以下、
のうちから選ばれる１種または２種を含有することを特徴とする請求項１乃至５のいずれか一項に記載の塗装耐久性に優れた構造用鋼材。 The component composition is further in mass%,
Ca: 0.0001% to 0.0100% and Mg: 0.0001% to 0.0100%,
The structural steel material excellent in coating durability according to any one of claims 1 to 5, wherein the structural steel material contains one or two selected from among them.
該防食下地層が無機ジンクリッチペイント、該下塗り層がエポキシ樹脂塗料、該中塗り層がふっ素樹脂上塗り塗料用の中塗り塗料、該上塗り層がふっ素樹脂上塗り塗料をそれぞれ用いてなることを特徴とする請求項７に記載の塗装耐久性に優れた構造用鋼材。 The coating film has an anticorrosion underlayer, an undercoat layer, an intermediate coat layer and an overcoat layer,
The anticorrosion underlayer is composed of an inorganic zinc rich paint, the undercoat layer is an epoxy resin paint, the intermediate coat layer is an intermediate coat for a fluororesin overcoat, and the overcoat layer is a fluororesin overcoat. The structural steel material excellent in coating durability according to claim 7.
The structure according to claim 9, wherein the structure is a bridge.
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