JP4207765B2 - Steel material for marine ballast tanks with excellent corrosion resistance - Google Patents
Steel material for marine ballast tanks with excellent corrosion resistance Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims description 97
- 239000010959 steel Substances 0.000 title claims description 97
- 238000005260 corrosion Methods 0.000 title claims description 62
- 230000007797 corrosion Effects 0.000 title claims description 61
- 239000000463 material Substances 0.000 title claims description 60
- 239000011701 zinc Substances 0.000 claims description 42
- 229910052725 zinc Inorganic materials 0.000 claims description 25
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 23
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 229910052720 vanadium Inorganic materials 0.000 claims description 8
- 229910052796 boron Inorganic materials 0.000 claims description 7
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 239000012535 impurity Substances 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910052758 niobium Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 229910052717 sulfur Inorganic materials 0.000 claims description 2
- 239000002987 primer (paints) Substances 0.000 description 36
- 239000000047 product Substances 0.000 description 21
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 19
- 230000000694 effects Effects 0.000 description 19
- 239000011248 coating agent Substances 0.000 description 15
- 238000000576 coating method Methods 0.000 description 15
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 15
- 238000000034 method Methods 0.000 description 10
- 239000004593 Epoxy Substances 0.000 description 9
- 239000003973 paint Substances 0.000 description 9
- 239000013535 sea water Substances 0.000 description 9
- 239000010953 base metal Substances 0.000 description 8
- 230000008439 repair process Effects 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
- 230000009471 action Effects 0.000 description 7
- 238000004381 surface treatment Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 230000002829 reductive effect Effects 0.000 description 5
- 238000003466 welding Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 238000005275 alloying Methods 0.000 description 3
- 238000005422 blasting Methods 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 238000010422 painting Methods 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000005266 casting Methods 0.000 description 2
- 238000009749 continuous casting Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 238000005488 sandblasting Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 2
- 101100493710 Caenorhabditis elegans bath-40 gene Proteins 0.000 description 1
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229920006334 epoxy coating Polymers 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000000670 limiting effect Effects 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- UOURRHZRLGCVDA-UHFFFAOYSA-D pentazinc;dicarbonate;hexahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[O-]C([O-])=O.[O-]C([O-])=O UOURRHZRLGCVDA-UHFFFAOYSA-D 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 239000013615 primer Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 229920002803 thermoplastic polyurethane Polymers 0.000 description 1
- 238000009849 vacuum degassing Methods 0.000 description 1
- 239000011592 zinc chloride Substances 0.000 description 1
- 235000005074 zinc chloride Nutrition 0.000 description 1
- UGZADUVQMDAIAO-UHFFFAOYSA-L zinc hydroxide Chemical compound [OH-].[OH-].[Zn+2] UGZADUVQMDAIAO-UHFFFAOYSA-L 0.000 description 1
- 229940007718 zinc hydroxide Drugs 0.000 description 1
- 229910021511 zinc hydroxide Inorganic materials 0.000 description 1
- 239000011787 zinc oxide Substances 0.000 description 1
Description
本発明は、船舶用鋼材に関し、特に、海水、高温多湿の厳しい環境下で使用されるバラストタンク用鋼材について、補修塗装寿命延長および補修塗装作業軽減の観点から、その耐食性を向上させようとするものである。 The present invention relates to marine steel materials, and in particular, to improve the corrosion resistance of steel materials for ballast tanks used in severe environments of seawater and high temperature and humidity, from the viewpoint of extending the repair coating life and reducing the repair coating work. Is.
バラストタンクは、海水が出入りすることから、厳しい腐食環境下にあり、通常、その防食は、エポキシ系塗料と電気防食とが併用されている。しかし、それらの防食を講じていても、バラストタンクの腐食は激しい状態である。すなわち、バラストタンクの海水充満時においては、海水に完全に浸されている部分は、電気防食が働き、腐食の進行を抑えられる。しかし、バラストタンクの最上部付近、特にアッパーデッキの裏側は海水に完全に漬からず、海水飛沫の状態である。そのため、このような部位では、電気腐食が働かず、さらに太陽光により、鋼板が高温に曝されるため、厳しい腐食環境下となり、激しい腐食状態となる。また、バラストタンクに海水がない場合においては、海水の残留付着塩分の作用によって、厳しい腐食状態となる。このように厳しい腐食環境下にあるバラストタンクの塗膜寿命は、約１０年といわれており、船の寿命（２０年）の半分である。従って、残りの１０年は、補修塗装で安全性を維持しなければならない。バラストタンクでは、このような厳しい腐食環境による激しい腐食状態、そして、それに起因した狭い空間での補修再塗装という悪条件下での作業が重大な問題であるため、補修塗装寿命の延長、および補修塗装作業の軽減を達成せしめる耐食性鋼材の開発が望まれている。 The ballast tank is in a severe corrosive environment because seawater enters and exits, and the anticorrosion is usually used in combination with epoxy paint and electrocorrosion protection. However, even if these anticorrosion measures are taken, the corrosion of the ballast tank is in a severe state. That is, when the ballast tank is filled with seawater, the portion that is completely immersed in seawater acts as an anticorrosion, and the progress of corrosion can be suppressed. However, the vicinity of the uppermost part of the ballast tank, particularly the back side of the upper deck, is not completely immersed in seawater and is in the state of seawater splashes. Therefore, in such a part, since electric corrosion does not work and the steel plate is exposed to high temperature by sunlight, it becomes a severe corrosive environment and becomes a severe corrosive state. Moreover, when there is no seawater in a ballast tank, it will be in a severe corrosion state by the effect | action of the residual adhering salt content of seawater. The coating film life of the ballast tank in such a severe corrosive environment is said to be about 10 years, which is half of the life of the ship (20 years). Therefore, for the remaining 10 years, safety must be maintained by repair painting. In ballast tanks, the severe corrosion caused by such a severe corrosive environment, and the work under adverse conditions of repainting in a narrow space resulting from this, is a serious problem. Development of corrosion-resistant steel that can reduce painting work is desired.
一方、バラストタンクの耐食化に関する鋼材側からの対策としては、以下のものが提案されている。 On the other hand, the following have been proposed as countermeasures from the steel side regarding the corrosion resistance of the ballast tank.
特許文献１には、Ｐ：０.０３〜０.１０％、Ｃｕ：０.１〜１.０％、Ｎｉ：０.１〜１.０％を添加した鋼材にエポキシ、ピュアエポキシ、ウレタン樹脂などを塗布したバラストタンクが提案されている。これは下地金属の耐食性が向上するため、樹脂皮膜の接着劣化寿命が延長し、バラストタンクの耐久化が図られるとしている。そして、２０〜３０年にわたって、メンテナンスを不要にすることが可能になったとある。 In Patent Document 1, P: 0.03 to 0.10%, Cu: 0.1 to 1.0%, Ni: 0.1 to 1.0%, steel, epoxy, pure epoxy, urethane resin The ballast tank which applied etc. is proposed. This is because the corrosion resistance of the base metal is improved, so that the adhesive deterioration life of the resin film is extended and the ballast tank is made durable. And it has become possible to make maintenance unnecessary for 20 to 30 years.
特許文献２には、Ｃｒ：０.２〜５％を添加することで、また、特許文献３には、Ｃｒ：０.５〜３.５％を添加することで、耐食性が向上し、船舶のメンテナンスフリー化に寄与できるとある。 By adding Cr: 0.2 to 5% to Patent Document 2, and by adding Cr: 0.5 to 3.5% to Patent Document 3, corrosion resistance is improved. It can contribute to maintenance-free.
特許文献４には、Ｎｉ：０.１〜４.０％を添加することで、耐塗膜損傷性が向上し、補修塗装などの保守費用を大幅に削減できるとある。
しかし、特許文献１の技術では、下地金属の耐食性を向上させるため、Ｐ含有量が０.０３〜０.１０％と比較的多く添加されており、溶接性および溶接部靭性に問題があると考えられる。また、特許文献２〜３の技術ではＣｒ含有量が比較的高く、特許文献４の技術ではＮｉ含有量が比較的高く、いずれも製造コスト高となる問題があった。 However, in the technique of Patent Document 1, in order to improve the corrosion resistance of the base metal, a relatively large amount of P is added as 0.03 to 0.10%, and there is a problem in weldability and weld toughness. Conceivable. Moreover, in the techniques of Patent Documents 2 and 3, the Cr content is relatively high, and in the technique of Patent Document 4, the Ni content is relatively high.
そこで、本発明は、船舶バラストタンクの補修再塗装寿命の延長および補修再塗装作業の軽減に寄与すべく、上記のような溶接性、溶接部靭性の劣化や製造コストの高騰を回避できる、耐食性に優れた船舶バラストタンク用鋼材を提供することを目的とする。 Therefore, the present invention is able to avoid the deterioration of weldability, weld toughness and increase in manufacturing cost as described above in order to contribute to the extension of the repair repaint life of the ship ballast tank and the reduction of the repair repaint work. It aims at providing the steel material for ship ballast tanks excellent in.
一般に船舶に供される鋼材は、タールエポキシ塗料などによる塗装が施されている。塗装前には鋼材に表面処理が施される。表面処理は、一次表面処理と二次表面処理に分けられる。一次表面処理は、鋼材の加工、組み立て工程の期間中に鉄錆発生を防止することを目的とし、製鉄所や造船所などにおいて、鋼材の黒皮や鉄錆の除去を行い、その後、プライマーが塗布される。二次表面処理とは、鋼材の加工、組み立て期間中に、母材部のプライマーホールに起因して発生した鉄錆や、鋼材切断部および溶接部のプライマー損傷に起因して発生した鉄錆を除去し、再びプライマーを塗布する処理である。 In general, steel materials used for ships are painted with tar epoxy paint or the like. Surface treatment is applied to the steel before painting. The surface treatment is divided into a primary surface treatment and a secondary surface treatment. The primary surface treatment is aimed at preventing the occurrence of iron rust during the processing and assembling process of steel materials, and at the steelworks and shipyards, the steel skin and iron rust are removed, and then the primer is used. Applied. Secondary surface treatment refers to iron rust generated due to primer holes in the base metal part during primer processing and assembly, and iron rust generated due to primer damage in steel cut parts and welds. It is the process which removes and applies a primer again.
上記組み立てに関して、小組み段階においては、本塗装（タールエポキシ塗装）までの期間が長いために、本塗装までの防錆を目的として、小組み後、プライマー処理がなされる。一方、大組み段階においては、本塗装までの期間が短いために、プライマー処理はなされない。また、本塗装直前には、錆除去を目的として、全体的にブラスト処理がなされるが、プライマーが完全に除去されるわけでなく、残存している。なお、錆を除去する手段としては、サンドブラスト処理、パワーツール（グラインダー等）処理が主に行われており、プライマーとしては、ウオッシュプライマー、ジンクリッチプライマーがあるが、耐食性の観点から、ジンクリッチプライマーがよく使用されている。 Regarding the above assembly, in the small assembly stage, since the period until the main coating (tar epoxy coating) is long, primer treatment is performed after the small assembly for the purpose of rust prevention until the main coating. On the other hand, in the large assembly stage, since the period until the main coating is short, the primer treatment is not performed. Further, immediately before the main coating, blasting is generally performed for the purpose of removing rust, but the primer is not completely removed but remains. In addition, as a means for removing rust, sand blasting and power tool (grinder etc.) are mainly used. As primers, there are wash primer and zinc rich primer. From the viewpoint of corrosion resistance, zinc rich primer. Is often used.
したがって、造船完了時の鋼材表面の状態は、母材部および小組溶接部では、鋼材〜ジンクリッチプライマー〜タールエポキシ塗料の構造であり、大組溶接部では、鋼材〜タールエポキシ塗料の構造である。大部分は、ジンクリッチプライマーが存在する状態にある。 Therefore, the state of the steel surface at the time of shipbuilding completion is the structure of steel material-zinc rich primer-tar epoxy paint in the base metal part and the small set welded part, and the structure of steel material-tar epoxy paint in the large set welded part. . Mostly in the presence of zinc rich primers.
一方、これまでの、船舶用鋼材の耐食化の研究は、鋼材自身を耐食化することで、錆発生を抑制し、塗膜の剥離寿命を延長させようとするものであった。観点は、鋼材自身のみの耐食化であった。一方、実際に船舶に供用される材料は、上記のとおり、ジンクリッチプライマーが併用されている。船舶竣工後、供用されてからも腐食に対してジンクリッチプライマーが影響していると考えられる。そこで、本発明では、鋼材の溶接性や溶接部靭性の劣化、製造コストの高騰を回避するという観点から、ジンクリッチプライマーと鋼材の相互作用を利用した鋼材成分の検討を行った。 On the other hand, the research on corrosion resistance of marine steel materials so far has been intended to suppress the generation of rust and extend the peeling life of the coating film by corrosion resistance of the steel material itself. The viewpoint was corrosion resistance only for the steel material itself. On the other hand, a zinc rich primer is used in combination with a material actually used for a ship as described above. The zinc rich primer is considered to have affected the corrosion even after the ship was completed. In view of this, in the present invention, from the viewpoint of avoiding deterioration of weldability and weld toughness of steel materials and increase in manufacturing cost, the steel material components using the interaction between the zinc rich primer and the steel materials were examined.
ジンクリッチプライマーの一般的な防食機能は、
１）ジンクリッチプライマー膜による鋼表面への水、酸素、塩化物などの腐食因子の透過を抑制する作用、
２）鋼が腐食する環境下に置かれたときに、ジンクリッリプライマー中に含まれるＺｎが鋼を犠牲防食する作用、
３）Ｚｎの腐食生成物膜による鋼への環境からの水、酸素、塩化物などの腐食因子の透過を抑制する作用、
である。
The general anticorrosion function of zinc rich primer is
1) Action of inhibiting the permeation of corrosion factors such as water, oxygen and chloride to the steel surface by the zinc rich primer film,
2) The action of Zn contained in the Zincuri primer when the steel is corroded to sacrifice and prevent the steel.
3) The action of inhibiting the penetration of corrosion factors such as water, oxygen and chloride from the environment into the steel by the corrosion product film of Zn,
It is.
そこで、ジンクリッチプライマーの防食効果を向上させる観点から、特に、上記３）のＺｎ腐食生成物膜の腐食因子の透過を抑制する作用を向上させる鋼材の化学成分の検討を行った。 Therefore, from the viewpoint of improving the anticorrosion effect of the zinc rich primer, the chemical components of the steel material that improve the action of suppressing the permeation of the corrosion factor of the Zn corrosion product film of the above 3) were examined.
一般的に、腐食性生物のイオン透過抵抗は、腐食生成物粒子の大きさと関係があり、腐食生成物粒子が微細であるほど、イオン透過抵抗は高くなる。したがって、Ｚｎの腐食生成物粒子を微細にできる元素の検討を行った。ここでいうＺｎの腐食生成物は、塩基性炭酸亜鉛、酸化亜鉛、水酸化亜鉛、塩基性塩化亜鉛などである。Ｎｉ、Ｃｕ、Ｃｒ、Ｍｏなどの合金元素を添加した鋼を溶製し、凝固させた鋼片を熱間圧延して鋼板となし、スケール除去後、ジンリッチプライマーを塗布して、小型暴露試験片を作製した。この試験片を、バラストタンクの上部環境を模擬した腐食環境（４０℃海水浸漬⇔４０℃湿度１００％大気、１サイクル７日）に、半年間暴露した。その後、形成されたＺｎの腐食生成物の粒子の大きさを、Ｘ線回折による半価幅および電子顕微鏡観察により、評価した。その結果、いずれの合金元素についても、腐食生成物を微細にする効果が認められた。合金元素（Ｘ）を添加した鋼材に形成されたＺｎ腐食生成物は、ＸとＦｅ、そしてＺｎが混合した酸化物、水酸化物、塩化物となっていたことから、ＸとＦｅが、Ｚｎ腐食生成物結晶に含まれることが、粒子を微細にしたものと考えられる。ただし、検討した合金元素の中で、腐食生成物を最も微細にしたのは、Ｎｉであった。 In general, the ion permeation resistance of corrosive organisms is related to the size of the corrosion product particles, and the finer the corrosion product particles, the higher the ion permeation resistance. Therefore, the element which can make the corrosion product particle | grains of Zn fine was examined. The corrosion products of Zn here are basic zinc carbonate, zinc oxide, zinc hydroxide, basic zinc chloride and the like. Steel with added alloying elements such as Ni, Cu, Cr, Mo is melted, and the solidified steel pieces are hot rolled to form steel plates. After removing the scale, a gin-rich primer is applied, and a small exposure test. A piece was made. This test piece was exposed to a corrosive environment (40 ° C. seawater immersion bath 40 ° C. humidity 100% air, 1 cycle 7 days) simulating the upper environment of the ballast tank for six months. Thereafter, the size of the formed corrosion product particles of Zn was evaluated by half width by X-ray diffraction and observation by an electron microscope. As a result, the effect of refining the corrosion products was recognized for any alloy element. Since the Zn corrosion products formed on the steel material to which the alloying element (X) was added were oxides, hydroxides, and chlorides mixed with X and Fe, and Zn, X and Fe were changed to Zn. It is considered that the particles are made fine by being contained in the corrosion product crystals. However, among the alloying elements studied, it was Ni that made the corrosion product the finest.
以上の検討より、鋼へのＮｉ添加が、Ｚｎ腐食生成物のイオン透過抵抗を最も上昇させ、ジンクリッチプライマーによる腐食効果を、より向上させることがわかった。 From the above examination, it was found that the addition of Ni to the steel most increased the ion permeation resistance of the Zn corrosion product and further improved the corrosion effect by the zinc rich primer.
すなわち、本発明は、スケールを除去した鋼材の表面にジンクリッチプライマーを塗布してなるジンクリッチプライマー塗布鋼材であって、前記鋼材が、質量％で、Ｃ：０.０３〜０.２％、Ｓｉ：０.５％以下、Ｍｎ：２.０％以下、Ｐ：０.０３％以下、Ｓ：０.０１％以下、Ａｌ：０.００５〜０.０６％、Ｎｉ：０.１〜１.０％、Ｎ：０.００２０〜０.００６５％、Ｔｉ：０.００５〜０.０２４％、を含有し、残部Ｆｅおよび不可避的不純物からなることを特徴とする耐食性に優れた船舶バラストタンク用鋼材である。 That is, the present invention is a zinc rich primer-coated steel material obtained by applying a zinc rich primer to the surface of a steel material from which scale has been removed, wherein the steel material is in mass%, C: 0.03 to 0.2%, Si: 0.5% or less, Mn: 2.0% or less, P: 0.03% or less, S: 0.01% or less, Al: 0.005-0.06%, Ni: 0.1-1 Ship ballast tank excellent in corrosion resistance, characterized by containing 0.0%, N: 0.0001 to 0.0063%, Ti: 0.005 to 0.024%, and the balance being Fe and inevitable impurities Steel material.
本発明では、前記鋼材が、Ｆｅの一部に代えて、質量％で、
Ｃｕ：０.１〜０.５％、Ｍｏ：０.００５〜０.５％のうちから選ばれた１種または２種、および/または、
Ｎｂ：０.０３％以下、Ｖ：０.２％以下、Ｂ：０.００２％以下のうちから選ばれた１種または２種以上、および/または、
Ｃａ：０.０１％以下、ＲＥＭ：０.０１５％以下のうちから選ばれた１種または２種、
を含有するものであってもよい。
In the present invention, the steel material is in mass% instead of part of Fe,
One or two selected from Cu: 0.1 to 0.5%, Mo: 0.005 to 0.5%, and / or
Nb: not more than 0.03%, V: not more than 0.2%, B: not more than 0.002%, and / or
One or two selected from Ca: 0.01% or less, REM: 0.015% or less,
May be contained.
本発明によれば、鋼材への比較的少ないＮｉ添加とジンクリッチプライマーの併用により、バラストタンク内の防食環境で優れた耐食性を示すので、製造コストの高騰を抑え、溶接性、溶接部靭性を確保しつつ、船舶バラストタンクの補修再塗装寿命の延長および補修再塗装作業の軽減に大きく寄与することができる。 According to the present invention, the combination of a relatively small amount of Ni added to the steel and the zinc rich primer provides excellent corrosion resistance in the anti-corrosion environment in the ballast tank, so that the rise in manufacturing costs is suppressed, and weldability and weld toughness are reduced. While ensuring, it can greatly contribute to the extension of the repair and repaint life of the ship ballast tank and the reduction of repair and repaint work.
まず、本発明の鋼材の組成限定理由について説明する。なお、以下、質量％は単に％と記す。 First, the reasons for limiting the composition of the steel material of the present invention will be described. Hereinafter, mass% is simply referred to as%.
Ｃ：０.０３〜０.２％
Ｃは、鋼材の強度を増加させる元素であり、本発明では所望の強度を得るために、０.０３％以上の含有を必要とする。一方、０.２％を超える含有は、ＨＡＺ（：溶接熱影響部）の靭性を劣化させる。このため、Ｃは０.０３〜０.２％の範囲に限定した。なお、強度、靭性の観点から、好ましくは０.０５〜０.１８％である。
C: 0.03 to 0.2%
C is an element that increases the strength of the steel material. In the present invention, the content of 0.03% or more is required to obtain a desired strength. On the other hand, the content exceeding 0.2% deteriorates the toughness of HAZ (: welding heat affected zone). For this reason, C was limited to the range of 0.03 to 0.2%. In addition, from the viewpoint of strength and toughness, it is preferably 0.05 to 0.18%.
Ｓｉ：０.５％以下
Ｓｉは、脱酸剤として作用するとともに、鋼材の強度を増加させる元素であり、本発明では、０.１％以上の含有が好ましいが、０.５％を超える含有は、鋼の靭性を劣化させる。このため、Ｓｉは０.５％以下の範囲に限定した。
Si: 0.5% or less Si is an element that acts as a deoxidizer and increases the strength of the steel material. In the present invention, the content is preferably 0.1% or more, but more than 0.5%. Degrades the toughness of steel. For this reason, Si was limited to the range of 0.5% or less.
Ｍｎ：２.０％以下
Ｍｎは、鋼材の強度を増加させる元素であるが、２.０％を超える含有は、鋼の靭性および溶接性を低下させる。このため、Ｍｎは２.０％以下に限定した。好ましくは、０.８〜１.８％である。
Mn: 2.0% or less Mn is an element that increases the strength of the steel material. However, the content exceeding 2.0% decreases the toughness and weldability of the steel. For this reason, Mn was limited to 2.0% or less. Preferably, it is 0.8 to 1.8%.
Ｐ：０.０３％以下
Ｐは、耐食性向上に有効な元素であるが、鋼の母材靭性、さらに溶接性および溶接部靭性を劣化させる。したがって、できるだけ低減するのが好ましいが、０.０３％までは許容できる。０.０３％を超えて含有すると母材靭性、溶接性および溶接部靭性が顕著に低下する。このため、Ｐは０.０３％以下に限定した。
P: 0.03% or less P is an element effective for improving corrosion resistance, but deteriorates the base metal toughness of steel, weldability and weld zone toughness. Therefore, it is preferable to reduce it as much as possible, but it is acceptable up to 0.03%. If the content exceeds 0.03%, the base metal toughness, weldability and weld zone toughness are significantly reduced. For this reason, P was limited to 0.03% or less.
Ｓ：０.０１％以下
Ｓは、靭性および溶接性を劣化する有害な元素であることから、可能な限り低減する必要がある。したがって、０.０１％以下に限定した。
S: 0.01% or less Since S is a harmful element that deteriorates toughness and weldability, it must be reduced as much as possible. Therefore, it was limited to 0.01% or less.
Ａｌ：０.００５〜０.０６％
Ａｌは、脱酸剤として作用する元素であり、本発明では０.００５％以上の含有を必要とする。一方、０.０６％を超えて含有すると、鋼の靭性が劣化する。このため、Ａｌは０.００５〜０.０６％の範囲に限定した。なお、好ましくは０.０１０〜０.０５％である。
Al: 0.005 to 0.06%
Al is an element that acts as a deoxidizing agent, and in the present invention, it is necessary to contain 0.005% or more. On the other hand, if the content exceeds 0.06%, the toughness of the steel deteriorates. For this reason, Al was limited to the range of 0.005 to 0.06%. In addition, Preferably it is 0.010 to 0.05%.
Ｎｉ：０.１〜１.０％
Ｎｉは、本発明で最も重要な元素である。前述のようにＺｎ腐食生成物を微細にし、Ｚｎ腐食生成物による腐食因子の鋼への透過抵抗を高め、鋼の腐食を制御する働きがある。また、Ｆｅ腐食生成物を微細にする働きや、Ｆｅ腐食生成物の電荷を負化する作用で、塩化物イオンの地鉄表面への透過を抑制し、地鉄近傍のｐＨを高め、鋼の腐食を抑制する。この効果は、０.１％以上で発現する。１.０％を超えても、この効果は認められるが、経済的に不利となるため、０.１〜１.０％の範囲に限定した。
Ni: 0.1-1.0%
Ni is the most important element in the present invention. As described above, the Zn corrosion product is made finer, the permeation resistance of the corrosion factor by the Zn corrosion product to the steel is increased, and there is a function of controlling the corrosion of the steel. In addition, the action of making the Fe corrosion product fine and the action of negativeizing the charge of the Fe corrosion product suppress the permeation of chloride ions to the surface of the steel, increase the pH in the vicinity of the steel, Inhibits corrosion. This effect is manifested at 0.1% or more. Even if it exceeds 1.0%, this effect is recognized, but since it is economically disadvantageous, it is limited to the range of 0.1 to 1.0%.
Ｎ：０.００２０〜０.００６５％
Ｎは、鋼材の腐食とともに溶出し、ＮＨ3を形成して、地鉄近傍のｐＨを高め、その後の鋼の腐食を抑制する。このような効果は０.００２０％以上の含有で認められる。一方、０.００６５％を超えて含有すると、溶鋼鋳込み時にスラブの割れ発生や、ＨＡＺの靭性が劣化する。そのため、０.００２０〜０.００６５％の範囲に限定した。
N: 0.000020 to 0.0069%
N elutes with the corrosion of the steel material, forms NH 3 , raises the pH in the vicinity of the ground iron, and suppresses subsequent corrosion of the steel. Such an effect is recognized when the content is 0.000020% or more. On the other hand, if the content exceeds 0.0063%, slab cracking and HAZ toughness deteriorate during casting of molten steel. Therefore, it was limited to the range of 0.0010% to 0.0069%.
Ｔｉ：０.００５〜０.０２４％
Ｔｉは、Ｎと結合し、ＴｉＮとして析出し、結晶粒の微細化に寄与する元素である。ＴｉＮは、とくに溶接時のオーステナイト粒の粗大化を抑制する効果を有する。このような効果は、０.００５％以上のＴｉ含有で顕著に認められる。一方、０.０２４％を超える含有は、固溶Ｔｉ量の増大や、ＴｉＮ粒の粗大化をもたらし、溶接時のオーステナイト粒粗大化を抑制する効果が低減し、ＨＡＺの靭性の劣化をもたらす。このため、Ｔｉは０.００５〜０.０２４％の範囲に限定した。
Ti: 0.005-0.024%
Ti is an element that combines with N, precipitates as TiN, and contributes to refinement of crystal grains. TiN particularly has an effect of suppressing the coarsening of austenite grains during welding. Such an effect is noticeable when the Ti content is 0.005% or more. On the other hand, if the content exceeds 0.024%, the amount of solute Ti is increased and the TiN grains are coarsened, the effect of suppressing the austenite grain coarsening during welding is reduced, and the toughness of the HAZ is deteriorated. For this reason, Ti was limited to the range of 0.005 to 0.024%.
上記した基本成分に加えて、Ｃｕ、Ｍｏのうちの１種または２種、および/または、Ｎｂ、Ｖ、Ｂのうちの１種または２種以上、および/または、Ｃａ、ＲＥＭのうちの１種または２種を、おのおの次の量で含有することができる。 In addition to the basic components described above, one or more of Cu and Mo and / or one or more of Nb, V and B, and / or one of Ca and REM Species or two can be included in each of the following amounts.
Ｃｕ：０.１〜０.５％、Ｍｏ：０.００５〜０.５％のうちの１種または２種
ＣｕはＮｉと同様、Ｚｎ腐食生成物を微細にし、Ｚｎ腐食生成物による腐食因子の鋼への透過抵抗を高め、鋼の腐食を抑制する働きがあるが、その効果はＮｉほど大きくない。ただし、Ｎｉのように高価な金属でないことに鑑みて、補助的に添加することができる。０.１％未満では、効果が小さく、０.５％以上では効果が飽和する。したがって、Ｃｕは、０.１〜０.５％の範囲とするのがよい。
Cu: 0.1 to 0.5%, Mo: 0.005 to 0.5% One or two of Cu Cu, like Ni, makes Zn corrosion products finer, corrosion factors due to Zn corrosion products Although it has a function of increasing the permeation resistance to steel and suppressing the corrosion of steel, its effect is not as great as that of Ni. However, in view of the fact that it is not an expensive metal like Ni, it can be supplementarily added. If it is less than 0.1%, the effect is small, and if it is 0.5% or more, the effect is saturated. Therefore, Cu should be in the range of 0.1-0.5%.
また、ＭｏもＮｉと同様、Ｚｎ腐食生成物を微細にし、Ｚｎ腐食生成物による腐食因子の鋼への透過抵抗を高め、鋼の腐食を抑制する働きがあるが、その効果はＮｉほど大きくない。しかし、腐食生成物中において、ＭｏＯ4 2-を形成し、塩化物イオンの地鉄表面への透過を抑制し、地鉄近傍のｐＨを高め、鋼の腐食を抑制する。この効果は、０.００５％以上で発現する。一方、０.５％を超えると経済的に不利となるので、Ｍｏは、０.００５〜０.５％の範囲とするのがよい。 Also, Mo, like Ni, has a function to make Zn corrosion products finer, increase the permeation resistance of corrosion factors to steel by Zn corrosion products, and suppress steel corrosion, but the effect is not as great as Ni. . However, MoO 4 2− is formed in the corrosion product, and the permeation of chloride ions to the surface of the steel is suppressed, the pH in the vicinity of the steel is increased, and the corrosion of the steel is suppressed. This effect is manifested at 0.005% or more. On the other hand, if it exceeds 0.5%, it is economically disadvantageous, so Mo is preferably in the range of 0.005 to 0.5%.
Ｎｂ：０.０３％以下、Ｖ：０.２％以下、Ｂ：０.００２％以下のうちの１種または２種以上
Ｎｂ、Ｖ、Ｂはいずれも、鋼材の強度を増加させる元素であり、必要に応じて選択して含有できる。このような効果を得るためには、Ｎｂ：０.００５％、Ｖ：０.０５％、Ｂ：０.０００３％以上をそれぞれ含有することが好ましい。一方、Ｎｂ：０.０３％、Ｖ：０.２％、Ｂ：０.００２％を超えてそれぞれ含有すると靭性が劣化する。このため、Ｎｂ：０.０３％以下、Ｖ：０.２％以下、Ｂ：０.００２％以下の範囲とするのがよい。
One or more of Nb: 0.03% or less, V: 0.2% or less, B: 0.002% or less Nb, V, and B are elements that increase the strength of steel materials. , And can be selected and contained as necessary. In order to obtain such an effect, it is preferable to contain Nb: 0.005%, V: 0.05%, and B: 0.0003% or more. On the other hand, if Nb: 0.03%, V: 0.2%, B: more than 0.002%, the toughness deteriorates. For this reason, it is good to set it as the range of Nb: 0.03% or less, V: 0.2% or less, and B: 0.002% or less.
Ｃａ：０.０１％以下、ＲＥＭ：０.０１５％以下のうちの１種または２種
Ｃａ、ＲＥＭは、いずれもＨＡＺの靭性向上に寄与する元素であり、必要に応じて選択して含有できる。このような効果は、Ｃａ：０.０００５％、ＲＥＭ：０.００１％以上の含有で顕著となるが、Ｃａ：０.０１％、ＲＥＭ：０.０１５％を超えて含有すると靭性が劣化する。このため、Ｃａ：０.１％以下、ＲＥＭ：０.０１５％以下の範囲とするのがよい。
Ca: 0.01% or less, REM: One or two of 015% or less Ca and REM are elements that contribute to improving the toughness of HAZ, and can be selected and contained as necessary. . Such an effect becomes remarkable when the content of Ca is 0.0005% and REM: 0.001% or more, but when the content exceeds Ca: 0.01% and REM: 0.015%, the toughness deteriorates. . For this reason, it is good to set it as the range of Ca: 0.1% or less and REM: 0.015% or less.
本発明の鋼材では、上記した成分以外の残部は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、Ｏ：０.００８％以下が許容できる。 In the steel material of the present invention, the balance other than the above components is Fe and inevitable impurities. As an inevitable impurity, O: 0.008% or less is acceptable.
つぎに、本発明の鋼材の好ましい製造方法について説明する。 Below, the preferable manufacturing method of the steel material of this invention is demonstrated.
まず、上記した組成の溶鋼を転炉、電気炉等の通常の溶製方法で溶製し、連続鋳造法、造塊法等の通常公知の鋳造方法で鋼素材とすることが好ましい。なお、溶鋼に取鍋精錬、真空脱ガス等の処理を付加しても良いことは言うまでもない。 First, the molten steel having the above composition is preferably melted by a normal melting method such as a converter or an electric furnace, and is made into a steel material by a generally known casting method such as a continuous casting method or an ingot-making method. It goes without saying that treatments such as ladle refining and vacuum degassing may be added to the molten steel.
ついで、得られた鋼素材を、結晶粒粗大化防止の観点から好ましくは１０５０〜１２５０℃の温度に加熱したのち、所望の寸法形状に熱間圧延するか、あるいは鋼素材の温度が熱間圧延可能な程度に高温である場合には、加熱することなく、あるいは均熱する程度で、ただちに所望の寸法形状の鋼材に熱間圧延することが好ましい。 Next, the obtained steel material is preferably heated to a temperature of 1050 to 1250 ° C. from the viewpoint of preventing grain coarsening, and then hot-rolled to a desired size or shape, or the temperature of the steel material is hot-rolled. When the temperature is as high as possible, it is preferable to immediately hot-roll to a steel material having a desired size and shape without heating or soaking.
本発明では、強度確保の観点から、熱間圧延では、熱間仕上圧延終了温度および熱間仕上圧延終了後の冷却速度を適正範囲とすることが好ましい。ここで、熱間仕上圧延終了温度は７００℃以上とするのが好ましく、また、熱間仕上圧延終了後は空冷、または冷却速度５０℃/ｓ以下の加速冷却を行うことができる。 In the present invention, from the viewpoint of securing strength, in hot rolling, it is preferable to set the hot finish rolling end temperature and the cooling rate after the hot finish rolling end to an appropriate range. Here, the finish temperature of hot finish rolling is preferably 700 ° C. or higher, and after the finish of hot finish rolling, air cooling or accelerated cooling with a cooling rate of 50 ° C./s or less can be performed.
このように製造した鋼材の表面にジンクリッチプライマー膜を形成するにあたっては、該膜の形成に先立って、鋼材の製造工程で発生した鋼材表面のスケールを除去する。これにより、ジンクリッチプライマー膜と鋼材の密着性が向上する。スケールを除去する手段は特に限定されず、ショットブラスト、サンドブラスト、ブラシケレンなどの慣用技術のいずれも用いうる。スケール除去後の鋼材表面に、Ｚｎを含有するジンクリッチプライマーを塗布して塗膜を形成する。形成されたジンクリッチプライマー膜中には、Ｚｎが質量％で２０％以上含有されることが好ましい。その限りにおいて、塗布の方法は、特に限定されず、スプレー、刷毛塗り、ロールコーター等の慣用技術のいずれを用いても良い。 In forming the zinc rich primer film on the surface of the steel material thus manufactured, the scale of the steel material surface generated in the steel material manufacturing process is removed prior to the formation of the film. Thereby, the adhesiveness of a zinc rich primer film | membrane and steel materials improves. The means for removing the scale is not particularly limited, and any conventional technique such as shot blasting, sand blasting or brush keren can be used. A zinc rich primer containing Zn is applied to the surface of the steel material after scale removal to form a coating film. The formed zinc rich primer film preferably contains 20% or more by mass of Zn. As long as this is the case, the application method is not particularly limited, and any conventional technique such as spraying, brushing, or roll coater may be used.
そして、造船後、本塗装を行うが、塗装は通常使用される防食塗料が使用できる。すなわち、これまで主流であったタールエポキシ塗料や、最近増加してきているタールフリーエポキシ塗料など、またウレタン塗料などが例示される。 And after shipbuilding, this coating is performed, but the coating used can be a commonly used anticorrosion paint. That is, tar epoxy paints that have been mainstream so far, tar-free epoxy paints that have been increasing recently, and urethane paints are exemplified.
なお、造船大組み溶接段階においては、本塗装までの期間が短いため、溶接部へのジンクリッチプライマーの再塗装は行われないことが多いが、竣工後の溶接部の耐食性を向上させるために、その部分へのジンクリッチプライマーの再塗布を行うことが望ましい。 In the shipbuilding large assembly welding stage, since the period until the main coating is short, repainting of the zinc rich primer on the welded part is often not performed, but in order to improve the corrosion resistance of the welded part after completion It is desirable to re-apply the zinc rich primer to the part.
転炉を用いて、表１に示す組成になる鋼を溶製し、連続鋳造によりスラブとなし、このスラブを加熱炉に装入して１１５０℃に加熱した後、熱間圧延し、厚鋼板（厚さ２０ｍｍ、幅３０００ｍｍ）からなる鋼材を得た。鋼Ａ〜Ｊは鋼材の組成が本発明を満たす例、鋼Ｋ〜Ｎは鋼材の組成が本発明を満たさない例である。 Using a converter, the steel having the composition shown in Table 1 is melted and formed into a slab by continuous casting. The slab is charged into a heating furnace and heated to 1150 ° C., and then hot rolled, A steel material made of (thickness 20 mm, width 3000 mm) was obtained. Steels A to J are examples in which the composition of the steel material satisfies the present invention, and steels K to N are examples in which the composition of the steel material does not satisfy the present invention.
かくして得られた鋼材について母材引張特性、衝撃特性を調査した。また、サブマージドアーク溶接での入熱５０ｋＪ/ｃｍ相当の熱サイクルを付与して再現したＨＡＺの衝撃特性（再現ＨＡＺ衝撃特性）を評価した。その結果、Ｐ含有量が本発明範囲を超える鋼Ｍでは、母材衝撃特性および再現ＨＡＺ衝撃特性が劣化した。 The base material tensile properties and impact properties of the steel materials thus obtained were investigated. Moreover, the impact characteristics (reproduced HAZ impact characteristics) of the HAZ reproduced by applying a thermal cycle equivalent to a heat input of 50 kJ / cm in submerged arc welding were evaluated. As a result, in steel M in which the P content exceeds the range of the present invention, the base metal impact characteristics and the reproduced HAZ impact characteristics deteriorated.
次に、それぞれの鋼材から試験片（厚さ２０ｍｍ、幅１００ｍｍ、長さ３００ｍｍ）を切り出し、その表面にショットブラスト処理を施してスケールを除去した。そして、該スケール除去後の表面にジンクリッチプライマーを塗布（膜厚：約１５μｍ）した試験片と、前記表面にジンクリッチプライマーを塗布しない試験片とを作製した。ついで、これらすべての試験片に、タールエポキシ塗料を塗布（膜厚：約２００μｍ）し、サンプルとした。サンプルＡＰ〜ＪＰは本発明例であり、サンプルＡＮ〜ＮＮ、およびサンプルＫＰ〜ＮＰは比較例である。 Next, a test piece (thickness 20 mm, width 100 mm, length 300 mm) was cut out from each steel material, and the surface was subjected to shot blasting to remove the scale. And the test piece which apply | coated zinc rich primer to the surface after this scale removal (film thickness: about 15 micrometers) and the test piece which does not apply a zinc rich primer to the said surface were produced. Next, tar epoxy paint was applied to all these test pieces (film thickness: about 200 μm) to prepare samples. Samples AP to JP are examples of the present invention, and samples AN to NN and samples KP to NP are comparative examples.
その後、カッターナイフで、サンプルの地鉄表面まで達する１５０ｍｍ長さのスクラッチを付加した。そして、これらのサンプルを、実船のバラストタンク内（アッパーデッキ裏）に装着し、暴露試験に供した。暴露期間は２年間である。暴露試験後、スクラッチ周囲のさび、および、さびに起因した塗膜膨れ、これらを合わせた面積（さび面積と称す。）を測定した。測定結果を表１に、ベース（サンプルＮＮ）に対する比であるさび面積率で示す。 Thereafter, a 150 mm long scratch reaching the surface of the sample iron was added with a cutter knife. These samples were mounted in the actual ship's ballast tank (back of the upper deck) and subjected to an exposure test. The exposure period is 2 years. After the exposure test, the rust around the scratch, the swelling of the coating film due to rust, and the combined area (referred to as rust area) were measured. The measurement results are shown in Table 1 as a rust area ratio which is a ratio to the base (sample NN).
表１に示したとおり、ベースとした現行材（サンプルＮＮ）に対し、鋼材に主にＮｉを添加した鋼Ａ〜Ｊのプライマー無塗布材（サンプルＡＮ〜ＪＮ）は、さび面積を減少させるが、その効果は顕著ではない。一方、同鋼Ａ〜Ｊのプライマー塗布材（サンプルＡＰ〜ＪＰ）は、現行材に対し、さび面積率が５０％以下となり、顕著な効果が認められる。なお、鋼材のＰ含有量が高すぎる鋼Ｍのプライマー塗布材（サンプルＭＰ）は、さび面積率が２９％と優れた耐食性を示すが、母材衝撃特性および再現ＨＡＺ衝撃特性が劣化している。以上のことから、鋼材へのＮｉ添加とプライマーの併用が、機械的特性を損なうことなく、耐食性を向上させるのに極めて有効であることがわかる。 As shown in Table 1, compared with the current base material (sample NN), the primer-uncoated materials (samples AN to JN) of steels A to J in which Ni is mainly added to the steel material reduce the rust area. The effect is not remarkable. On the other hand, the primer coating material (samples AP to JP) of the steels A to J has a rust area ratio of 50% or less with respect to the current material, and a remarkable effect is recognized. In addition, the primer application material (sample MP) of steel M in which the P content of the steel material is too high shows excellent corrosion resistance with a rust area ratio of 29%, but the base metal impact characteristics and the reproduced HAZ impact characteristics are deteriorated. . From the above, it can be seen that the addition of Ni to the steel and the combined use of the primer are extremely effective for improving the corrosion resistance without impairing the mechanical properties.
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| JP4790423B2 (en) * | 2006-01-17 | 2011-10-12 | 新日本製鐵株式会社 | Welded structural steel excellent in seawater corrosion resistance and ship ballast tank anticorrosion method using the same |
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