JP2002266052A - Marine steel having excellent coating film life property - Google Patents
Marine steel having excellent coating film life propertyInfo
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- JP2002266052A JP2002266052A JP2001066258A JP2001066258A JP2002266052A JP 2002266052 A JP2002266052 A JP 2002266052A JP 2001066258 A JP2001066258 A JP 2001066258A JP 2001066258 A JP2001066258 A JP 2001066258A JP 2002266052 A JP2002266052 A JP 2002266052A
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- steel
- less
- coating film
- environment
- ballast tank
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、塗膜寿命性に優
れた船舶用鋼材に関し、特に高温多湿等の厳しい環境下
で使用されるバラストタンク等の船舶用鋼材について、
腐食防止の観点から、その塗膜寿命の有利な延長を可能
ならしめようとするものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a marine steel material having excellent coating life, and more particularly to a marine steel material such as a ballast tank used in a severe environment such as high temperature and high humidity.
From the viewpoint of corrosion prevention, it is intended to advantageously extend the life of the coating film.
【０００２】[0002]
【従来の技術】バラストタンクは、高温多湿という特に
過酷な環境下で使用されることから、その防食に関して
は、従来から種々の対策が講じられている。通常、バラ
ストタンクの防食は、タールエポキシ樹脂塗料と電気防
食とを併用しているが、バラストタンク内には海水が出
入りすることから、厳しい腐食環境下にある。すなわ
ち、バラストタンク内に海水が充満している場合は、海
水に漬かっている部分は電気防食の効果によってほとん
ど腐食を受けないが、海水に漬かっていないバラストタ
ンクの最上部やアッパーデッキの裏側は、高温に加え、
飛沫帯という厳しい腐食環境下にある。一方、バラスト
タンク内に海水がない場合は、高温多湿環境となり、こ
の場合は電気防食の効果が期待できず、タールエポキシ
樹脂塗料のみの防食となる。また、バラストタンク内に
海水を充満させる際、海水中に含まれている小石や砂塵
等もバラストタンク内に侵入し、塗膜にスクラッチ
（傷）が生じてしまうため、スクラッチ部から腐食が進
行する。2. Description of the Related Art Since a ballast tank is used in a particularly severe environment of high temperature and high humidity, various measures have been conventionally taken to prevent corrosion. Normally, ballast tanks are corrosion-protected by using a tar epoxy resin paint and an electro-corrosion protection. However, since seawater flows into and out of the ballast tank, the ballast tank is in a severely corrosive environment. In other words, when the ballast tank is full of seawater, the part immersed in seawater is hardly corroded by the effect of cathodic protection, but the top part of the ballast tank not immersed in seawater and the back side of the upper deck are , High temperature,
It is in a severe corrosive environment called a splash zone. On the other hand, when there is no seawater in the ballast tank, the environment becomes high temperature and high humidity. Also, when the ballast tank is filled with seawater, pebbles and dust contained in the seawater also enter the ballast tank and cause scratches on the paint film. I do.
【０００３】このような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
しい腐食環境と悪条件下での塗装作業が必要という、重
大な問題があるため、鋼材面からの改善すなわち塗膜寿
命の延長が可能な船舶用鋼材の開発が望まれている。[0003] The coating film life of such a ballast tank is as follows:
It is said to be about 10 years, half the life of a ship (20 years). Therefore, the remaining 10 years must maintain safety with refinishing. Ballast tanks have the serious problem of requiring painting work under such severe corrosive environment and adverse conditions, so it is desirable to develop marine steel materials that can be improved from the steel surface, that is, extend the life of coating films. It is rare.
【０００４】ところで、海洋環境下での使用を目的とし
た耐海水鋼は、耐食性向上のためにCrやNi，Mo，Cu等が
添加され、飛沫帯用、海水用あるいはこれら両用といっ
た使用環境に合わせた種々の溶接構造用耐海水鋼が開発
されている。そして、これらは、水門や鋼矢板、ブイ、
桟橋などに使用されている。かような耐海水鋼として
は、特開昭51−25420 号公報に開示の鋼材が知られてい
るが、この鋼材の用途は上記したような海洋構造物や港
湾施設であり、その使用環境は大気温度程度の海水であ
る。また、特開昭63−255341号公報には、大気環境での
塩害性を向上させた溶接構造用耐食性鋼板が提案されて
いる。By the way, seawater-resistant steel intended for use in a marine environment is added with Cr, Ni, Mo, Cu or the like for the purpose of improving corrosion resistance, and is used in a use environment such as a spray zone, seawater, or both. Various combined seawater resistant steels for welded structures have been developed. And these are sluices, steel sheet piles, buoys,
It is used for piers. As such seawater-resistant steel, a steel material disclosed in JP-A-51-25420 is known, but the steel material is used for marine structures and port facilities as described above. It is seawater at about atmospheric temperature. Japanese Patent Application Laid-Open No. 63-255341 proposes a corrosion-resistant steel sheet for welded structures having improved salt damage in an atmospheric environment.
【０００５】上述したとおり、従来の耐海水鋼材問題と
している環境は、この発明で問題とする環境、すなわち
海水が出入りし、高温多湿となるバラストタンク内環境
とは、腐食環境が大きく異なる。すなわち、バラストタ
ンクの腐食環境は、上述したように海水の出入りがある
高温多湿環境であり、特にタンカーを想定した場合の腐
食環境は次のとおりである。中近東から日本に原油を輸
送する場合、日本から中近東までの往路は、貨油タンク
は空であるので、船のバランスを保ち、航行の安全を図
るためにバラストタンク内は海水をほぼ満水にする。こ
の時の腐食環境は、バラストタンクの中部〜下部は海水
中であり、バラストタンク上部では飛沫帯に近い状況で
ある。一方、貨油タンクに原油を満載し、中近東から日
本に向かう復路は、バラストタンク内は海水は抜いて空
とする。この時のバラストタンク内は、船底に残留した
海水と甲板からの熱で高温多湿環境となる。なお、バラ
ストタンクがこれらの腐食環境に曝される１サイクルは
約80日間である。[0005] As described above, the conventional environment which is considered to be a seawater resistant steel material has a significantly different corrosive environment from the environment which is a problem in the present invention, that is, the environment in a ballast tank in which seawater enters and exits and becomes hot and humid. That is, the corrosive environment of the ballast tank is a high-temperature and high-humidity environment where seawater enters and exits as described above. In particular, the corrosive environment when a tanker is assumed is as follows. When transporting crude oil from the Middle East to Japan, the cargo tanks are empty on the outbound route from Japan to the Middle East, so the ballast tank is almost completely filled with seawater to maintain the balance of the ship and ensure navigational safety. To The corrosive environment at this time is such that the middle to lower part of the ballast tank is in seawater and the upper part of the ballast tank is close to the splash zone. On the other hand, on the return trip from the Middle East to Japan where the crude oil tank is full of crude oil, the seawater is drained from the ballast tank and emptied. At this time, the inside of the ballast tank becomes a hot and humid environment due to the seawater remaining on the ship bottom and the heat from the deck. One cycle in which the ballast tank is exposed to these corrosive environments is about 80 days.
【０００６】[0006]
【発明が解決しようとする課題】現在、船舶に使用され
ている鋼材は、強度や靱性、溶接性を考慮した成分設計
およびプロセス設計により製造されているが、耐食性や
防食性に関しての対策はほとんど講じられていないのが
現状である。この発明は、上記の現状に鑑み開発された
もので、合金元素の添加によって、厳しい腐食環境、特
に高温多湿環境下においても塗膜寿命を効果的に延長す
ることができる、塗膜寿命性に優れた船舶用鋼材を提案
することを目的とする。At present, steel materials used for ships are manufactured by component design and process design in consideration of strength, toughness and weldability, but almost no measures are taken for corrosion resistance and corrosion resistance. At present it has not been taken. The present invention has been developed in view of the above situation. By adding an alloying element, it is possible to effectively extend the life of a coating film even in a severe corrosive environment, particularly in a high-temperature and high-humidity environment. The purpose is to propose excellent marine steel materials.
【０００７】なお、塗膜寿命とは、補修塗装あるいは全
面再塗装を施すまでの寿命を意味する。補修塗装あるい
は全面再塗装の実施時期について、その判断指標は明確
ではないが、一般に腐食により塗膜が損傷し、さび面積
がある程度まで広がった場合に、再塗装が必要と判断す
る。従って、さびによる塗膜損傷が軽減されれば、塗膜
寿命は延長される、すなわち塗膜寿命性は向上すること
になる。[0007] The life of the coating film means the life until repair painting or repainting is performed on the entire surface. Although the index for determining when to perform repair painting or repainting the entire surface is not clear, it is generally determined that repainting is necessary when the coating has been damaged by corrosion and the rust area has expanded to some extent. Therefore, if the coating damage due to rust is reduced, the coating life is extended, that is, the coating life is improved.
【０００８】[0008]
【課題を解決するための手段】さて、発明者らは、種々
の合金元素を種々の割合で含有させた暴露試験片を多数
作製し、これらの試験片を実際のバラストタンク内で２
年間の暴露試験に供した。その結果、主にCuレスでかつ
Niを添加した試験片で、塗膜スクラッチからのさびによ
る塗膜ふくれが、著しく軽減されることの知見を得た。
例えば、Niを１mass％添加し、かつCuを0.02mass％まで
低減した鋼材は、従来の鋼材に比べ、その膨れ面積は１
／10にまで低減した。また、MoやCo，Sb，Ｗを添加した
試験片についても、さびによる塗膜膨れが抑制されるこ
とが判明した。すなわち、これら合金元素は、スクラッ
チ部からの腐食の進行を抑制し、塗膜損傷を軽減する効
果があることが見出された。この発明は、上記の知見に
立脚するものである。Means for Solving the Problems Now, the present inventors have prepared a large number of exposure test pieces containing various alloy elements in various ratios, and put these test pieces in an actual ballast tank.
It was subjected to an annual exposure test. As a result, it is mainly Cu-less and
In the test piece to which Ni was added, it was found that blistering of the coating film due to rust from the coating film scratch was remarkably reduced.
For example, a steel material in which 1 mass% of Ni is added and Cu is reduced to 0.02 mass% has a swollen area of 1% as compared with a conventional steel material.
Reduced to / 10. In addition, it was also found that the swelling of the coating film due to rust was suppressed for the test pieces to which Mo, Co, Sb, and W were added. That is, it has been found that these alloy elements have an effect of suppressing the progress of corrosion from the scratch portion and reducing damage to the coating film. The present invention is based on the above findings.
【０００９】すなわち、この発明の要旨構成は次のとお
りである。 １．質量％で、Ｃ：0.001 〜0.025 ％、Si：0.60％以
下、Mn：0.10〜3.0 ％、Ｐ：0.030 ％以下、Ｓ：0.01％
以下、Al：0.10％以下、Ni：0.1 〜4.0 ％およびCu：0.
1 ％以下を含み、残部はFeおよび不可避的不純物の組成
になることを特徴とする塗膜寿命性に優れた船舶用鋼
材。That is, the gist of the present invention is as follows. 1. In mass%, C: 0.001 to 0.025%, Si: 0.60% or less, Mn: 0.10 to 3.0%, P: 0.030% or less, S: 0.01%
Hereinafter, Al: 0.10% or less, Ni: 0.1 to 4.0%, and Cu: 0.
Ship steel with excellent coating life, characterized by containing 1% or less, with the balance being Fe and inevitable impurities.
【００１０】２．上記１において、鋼材が、さらに質量
％で、Mo：0.05〜0.5 ％、Co：0.05〜0.5 ％、Ｗ：0.05
〜0.5 ％およびSb：0.05〜0.5 ％のうちから選んだ１種
または２種以上を含有する組成になる塗膜寿命性に優れ
た船舶用鋼材。[0010] 2. In the above item 1, the steel material further contains, by mass%, Mo: 0.05 to 0.5%, Co: 0.05 to 0.5%, W: 0.05
A steel material for ships having excellent coating film life, having a composition containing at least one selected from 0.5% to 0.5% and Sb: 0.05% to 0.5%.
【００１１】３．上記１または２において、鋼材が、さ
らに質量％で、Nb：0.005 〜0.20％、Ｖ：0.005 〜0.20
％、Ti：0.005 〜0.20％、REM：0.02％以下、Ca：0.005
％以下およびＢ：0.0003〜0.0050％のうちから選んだ
１種または２種以上を含有する組成になる塗膜寿命性に
優れた船舶用鋼材。3. In the above item 1 or 2, the steel material is further represented by mass%, Nb: 0.005 to 0.20%, V: 0.005 to 0.20%.
%, Ti: 0.005 to 0.20%, REM: 0.02% or less, Ca: 0.005%
% Or less and B: 0.0003 to 0.0050%. A marine steel material having a composition containing one or more selected from 0.0003 to 0.0050% and having excellent coating film life.
【００１２】[0012]
【発明の実施の形態】以下、この発明を具体的に説明す
る。まず、この発明において、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。なお、以下に示
す成分組成の％表示は「質量％」である。 Ｃ：0.001 〜0.025 ％ Ｃは、強度の向上に有効な元素であるが、含有量が 0.0
01％に満たないとその添加効果に乏しく、一方 0.025％
を超えると母材靱性および溶接部靱性の劣化を招くの
で、Ｃは 0.001〜0.025 ％の範囲に限定した。BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, the reason for limiting the composition of the steel material to the above range in the present invention will be described. The percentages of the component compositions shown below are “% by mass”. C: 0.001 to 0.025% C is an element effective for improving the strength, but the content is 0.0%.
If it is less than 01%, its effect is poor, while 0.025%
If C is exceeded, the toughness of the base metal and the toughness of the welded portion will be degraded. Therefore, C is limited to the range of 0.001 to 0.025%.
【００１３】Si：0.60％以下 Siは、脱酸剤として有用なだけでなく、鋼の強度を向上
させる点でも有用な元素であるが、あまりに多量に含有
させると母材靱性および溶接部靱性が劣化するので、Si
は0.60％以下に限定した。好ましくは0.15〜0.50％の範
囲である。Si: 0.60% or less Si is not only useful as a deoxidizing agent, but also a useful element in improving the strength of steel. However, when contained in an excessive amount, the base metal toughness and weld toughness are deteriorated. Deteriorates, so Si
Was limited to 0.60% or less. Preferably it is in the range of 0.15 to 0.50%.
【００１４】Mn：0.10〜3.0 ％ Mnは、鋼の強度のみならず、母材靱性および溶接部靱性
に大きな影響を与える元素であり、この発明では所望の
強度を確保するために0.10％以上含有させるものとし
た。しかしながら、3.0 ％を超えて含有させると母材靱
性および溶接部靱性に悪影響を及ぼすため、Mnは0.10〜
3.0 ％の範囲に限定した。好ましくは0.10〜2.0 ％の範
囲である。Mn: 0.10-3.0% Mn is an element that has a great effect not only on the strength of steel but also on the base metal toughness and weld toughness. In the present invention, Mn is contained in an amount of 0.10% or more in order to secure desired strength. It was made to be. However, if the content exceeds 3.0%, the base metal toughness and the weld toughness are adversely affected.
Limited to the 3.0% range. Preferably it is in the range of 0.10 to 2.0%.
【００１５】Ｐ：0.030 ％以下 Ｐは、母材靱性および溶接部靱性を劣化させるので、0.
03％以下に限定した。P: 0.030% or less P deteriorates the base metal toughness and the weld toughness.
Limited to 03% or less.
【００１６】Ｓ：0.01％以下 Ｓも、Ｐと同様、母材靱性および溶接部靱性を劣化させ
るので、0.01％以下に限定した。S: 0.01% or less S also deteriorates the base metal toughness and weld toughness similarly to P, so it was limited to 0.01% or less.
【００１７】Al：0.10％以下 Alは、脱酸剤として添加するが、含有量が0.10％を超え
ると溶接部靱性に悪影響を及ぼすため、0.10％以下で含
有させるものとした。Al: 0.10% or less Al is added as a deoxidizing agent, but if the content exceeds 0.10%, the toughness of the weld is adversely affected. Therefore, the content of Al is set to 0.10% or less.
【００１８】Ni：0.1 〜4.0 ％ Niは、塗膜膨れを顕著に抑制する元素として、この発明
において最も重要な元素である。その効果は、さび粒子
を緻密化し、地鉄への水、酸素、Cl等の腐食因子の透過
を阻止することによって発揮される。このように、ある
程度のさびが形成されたのち、このさび層が腐食因子の
透過を阻止することによって、その後の地鉄の腐食が抑
制される。腐食が抑制されれば、さび発生も少なく、さ
びによる塗膜膨れも抑制されるのである。この効果は、
Ni含有量が 0.1％未満では小さく、一方 4.0％を超える
と効果は飽和し、むしろ経済的に不利となるので、Ni量
は0.1〜4.0 ％の範囲に限定した。Ni: 0.1 to 4.0% Ni is the most important element in the present invention as an element that remarkably suppresses swelling of the coating film. The effect is exhibited by densifying the rust particles and preventing permeation of corrosive factors such as water, oxygen, and Cl into the base iron. In this way, after a certain amount of rust is formed, the rust layer prevents the penetration of corrosion factors, thereby suppressing the subsequent corrosion of the base iron. If the corrosion is suppressed, the generation of rust is small, and the swelling of the coating film due to the rust is also suppressed. This effect
If the Ni content is less than 0.1%, it is small, while if it exceeds 4.0%, the effect is saturated, and it is economically disadvantageous. Therefore, the Ni content is limited to the range of 0.1 to 4.0%.
【００１９】Cu：0.1 ％以下 Cuは、一般的に耐食性向上元素であり、橋梁など大気環
境で使用される耐候性鋼に添加されている。しかしなが
ら、この発明で対象とするバラストタンクの内部環境は
高温多湿であって、ほとんど濡れている状態にあるが、
かような環境ではCuは有効に働くどころか、逆に不利に
働く。これは、Cuが、さびの緻密化促進と鋼の溶解活性
化という２つの作用を有しているためである。すなわ
ち、大気環境では濡れている時間が比較的短く、そのた
め鋼の溶解時間が短い。従って、この場合には、Cuのさ
びの緻密化促進作用により形成された保護性さび層が、
Cuの溶解活性化による鋼の腐食反応を抑制する。一方、
常に濡れている状態では、Cuの溶解活性化による鋼の腐
食反応が、Cuのさびの緻密化促進作用によるさび層の保
護作用より大きくなるため、鋼の腐食が進行する。鋼の
腐食が進行すれば、塗膜膨れも進行する。ここに、Cu量
が 0.1％を超えると鋼の腐食ひいては塗膜膨れが進行す
るようになるので、Cu量は 0.1％以下に制限した。Cu: 0.1% or less Cu is generally an element for improving corrosion resistance, and is added to weathering steel used in an atmospheric environment such as a bridge. However, although the internal environment of the ballast tank targeted by the present invention is hot and humid, it is almost wet,
In such an environment, Cu does not work effectively, but rather works disadvantageously. This is because Cu has two functions, that is, promotion of densification of rust and dissolution activation of steel. That is, in the atmospheric environment, the wet time is relatively short, and therefore the melting time of the steel is short. Therefore, in this case, the protective rust layer formed by the rust promoting action of rust of Cu,
Suppress corrosion reaction of steel due to activation of dissolution of Cu. on the other hand,
In a constantly wet state, the corrosion reaction of the steel due to the activation of dissolution of Cu becomes greater than the protective action of the rust layer due to the action of Cu to promote the densification of the rust, so that the corrosion of the steel proceeds. As the corrosion of the steel progresses, the coating swells. Here, if the amount of Cu exceeds 0.1%, corrosion of the steel and eventually swelling of the coating film proceed, so the amount of Cu was limited to 0.1% or less.
【００２０】以上、必須成分について説明したが、この
発明では上記した必須成分の他に、以下の成分を適宜含
有させることができる。 Mo，Co，Ｗ，Sb：0.05〜0.5 ％ Mo，Co，ＷおよびSbはいずれも、塗膜膨れを抑制する効
果があるが、含有量が0.05％未満ではその効果が小さ
く、一方 0.5％を超えると効果が飽和し、むしろ経済的
に不利となるので、これらの元素は単独添加または複合
添加いずれの場合においても、それぞれ0.05〜0.5 ％の
範囲で含有させるものとした。While the essential components have been described above, in the present invention, the following components can be appropriately contained in addition to the above-mentioned essential components. Mo, Co, W, Sb: 0.05-0.5% Mo, Co, W, and Sb all have the effect of suppressing the swelling of the coating film, but when the content is less than 0.05%, the effect is small. If the content exceeds this, the effect is saturated, and it is economically disadvantageous. Therefore, these elements are contained in the range of 0.05 to 0.5% in either case of single addition or multiple addition.
【００２１】Nb，Ti，Ｖ：0.005 〜0.20％ Nb，TiおよびＶはいずれも、鋼材の強度を増加させる元
素であるが、含有量が0.005 ％に満たないとその添加効
果に乏しく、一方0.20％を超えると効果が飽和するた
め、これらの元素は単独添加または複合添加いずれの場
合においても、それぞれ 0.005〜0.20％の範囲で含有さ
せるものとした。Nb, Ti, V: 0.005 to 0.20% Nb, Ti and V are elements that increase the strength of the steel material. However, if the content is less than 0.005%, the effect of adding Nb, Ti, and V is poor. %, The effect saturates. Therefore, these elements are contained in the range of 0.005 to 0.20% in either case of single addition or composite addition.
【００２２】REM ：0.02％以下 REM は、溶接部靱性の向上に有効に寄与するが、含有量
が0.02％を超えると鋼材の清浄度が劣化するので、0.02
％以下で含有させるものとした。REM: 0.02% or less REM effectively contributes to the improvement of weld toughness. However, if the content exceeds 0.02%, the cleanliness of steel deteriorates.
% Or less.
【００２３】Ca：0.005 ％以下 Caも、REM と同様、溶接部靱性の向上に有効に寄与する
が、含有量が 0.005％を超えるとやはり鋼材の清浄度が
劣化するので、0.005 ％以下で含有させるものとした。Ca: 0.005% or less Ca, like REM, also effectively contributes to the improvement of weld toughness. However, if the content exceeds 0.005%, the cleanliness of steel also deteriorates. Therefore, the content of Ca is 0.005% or less. It was made to be.
【００２４】Ｂ：0.0003〜0.0050％ Ｂは、強度の向上に有利な元素であるが、含有量が0.00
03％に満たないとその添加効果に乏しく、一方0.0050％
を超えると母材靱性および溶接部靱性を劣化させるの
で、Ｂは0.0003〜0.0050％の範囲で含有させるものとし
た。B: 0.0003% to 0.0050% B is an element which is advantageous for improving the strength, but has a content of 0.0003% to 0.0050%.
If it is less than 03%, its effect is poor, while 0.0050%
If B exceeds B, the base metal toughness and the toughness of the welded part are deteriorated. Therefore, B is contained in the range of 0.0003 to 0.0050%.
【００２５】次に、この発明鋼材の製造方法について説
明する。この発明鋼材の製造方法については特に限定さ
れることはなく、従来公知の方法で製造すれば良い。す
なわち、転炉、電気炉等通常の方法で溶製したのち、連
続鋳造法あるいは造塊法により素材とする。また、溶製
に際しては、真空脱がス精錬等を実施しても良い。つい
で、これら素材を、加熱炉等で加熱したのち、あるいは
加熱なしで直接、熱間圧延により所望の形状に圧延す
る。Next, a method for producing the steel material of the present invention will be described. The method for producing the steel of the present invention is not particularly limited, and it may be produced by a conventionally known method. That is, after being melted by a usual method such as a converter or an electric furnace, the raw material is formed by a continuous casting method or an ingot forming method. Further, at the time of smelting, vacuum refining may be performed. Then, after heating these materials in a heating furnace or the like, or directly without heating, the materials are rolled into a desired shape by hot rolling.
【００２６】[0026]
【実施例】表１に示す成分組成になる鋼を転炉で溶製
し、連続鋳造法でスラブとした。ついで、これらスラブ
を加熱したのち、熱間圧延により板厚：25mm、板幅：25
00mmの鋼板とした。これらの鋼板の引張特性および衝撃
特性を調査した。また、溶接部靱性として、入熱：50 k
J/cm、溶接熱影響部：１mm相当の再現熱サイクルを付与
し、シャルピー衝撃試験により０℃における吸収エネル
ギーvE0を測定した。EXAMPLE Steel having the composition shown in Table 1 was melted in a converter and made into a slab by a continuous casting method. Then, after heating these slabs, the sheet thickness: 25 mm and the sheet width: 25 by hot rolling.
It was a 00 mm steel plate. The tensile properties and impact properties of these steel sheets were investigated. In addition, heat input: 50 k
J / cm, heat affected zone of welding: A reproducible heat cycle equivalent to 1 mm was applied, and the absorbed energy vE 0 at 0 ° C. was measured by a Charpy impact test.
【００２７】さらに、これら鋼板から５mm×100mm ×20
0 mmの暴露試験片を採取し、これらの試験片に、ショッ
トブラスト後、ジンクリッチプライマー (約15μm)、つ
いでタールエポキシ樹脂塗料 (約200 μm)を塗布した。
その後、カッターナイフで、試験片の地鉄表面まで達す
る80mm長さのスクラッチを付加した。そして、これらの
試験片を、実船のバラストタンク内に装着し、暴露試験
に供した。暴露期間は２年間である。このバラストタン
ク内の環境は、バラストタンク内に海水が入っている期
間：約40日、バラストタンク内に海水が入っていない期
間：約40日を１サイクルとした乾湿繰り返し環境であっ
た。暴露試験後、スクラッチ周囲のさびに起因した塗膜
膨れ面積を測定した。上記の調査結果を表２に示す。Further, 5 mm × 100 mm × 20 mm
The exposed test pieces of 0 mm were collected, and after the shot blasting, a zinc-rich primer (about 15 μm) and then a tar epoxy resin paint (about 200 μm) were applied to these test pieces.
Thereafter, a scratch having a length of 80 mm reaching the surface of the base steel of the test piece was added with a cutter knife. Then, these test pieces were mounted in a ballast tank of an actual ship and subjected to an exposure test. The exposure period is 2 years. The environment in the ballast tank was a dry-humidity repeated environment in which the period during which seawater was in the ballast tank: about 40 days, and the period when no seawater was in the ballast tank: about 40 days. After the exposure test, the swollen area of the coating film caused by rust around the scratch was measured. Table 2 shows the results of the above investigation.
【００２８】[0028]
【表１】 [Table 1]
【００２９】[0029]
【表２】 [Table 2]
【００３０】表２に示したとおり、発明例（鋼No.1〜1
0）の塗膜膨れ面積は68〜527 mm2 であり、比較例に比
べて格段に小さく、優れた耐塗膜損傷性を有しているこ
とが分かる。。一方、比較例のうち、No.11, 14 はCu量
が、No.12 はNi量が、No.15 はＣ量とCu量とNi量が、そ
れぞれこの発明の適正範囲を逸脱しているため、塗膜膨
れ面積は極めて大きかった。また、No.13 は、Ｐ量がこ
の発明の上限を超えているため、塗膜膨れ面積は発明例
と同程度であるが、母材靱性および溶接部靱性が劣化し
ている。なお、No.1〜４の結果から、Ni量を増加させる
ことが塗膜膨れ面積の減少には極めて有効であることが
分かる。As shown in Table 2, the invention examples (Steel Nos. 1 to 1)
The swollen area of the coating film of (0) is 68 to 527 mm 2, which is much smaller than that of the comparative example, indicating that the film has excellent coating film damage resistance. . On the other hand, among the comparative examples, Nos. 11 and 14 had Cu amounts, No. 12 had Ni amounts, and No. 15 had C amounts, Cu amounts and Ni amounts deviating from the proper ranges of the present invention. Therefore, the swollen area of the coating film was extremely large. In No. 13, since the P content exceeded the upper limit of the present invention, the swollen area of the coating film was almost the same as that of the invention example, but the base material toughness and weld toughness were deteriorated. From the results of Nos. 1 to 4, it can be seen that increasing the amount of Ni is extremely effective in reducing the swollen area of the coating film.
【００３１】[0031]
【発明の効果】この発明の船舶用鋼材は、優れた耐塗膜
損傷性を有し、苛酷な腐食環境であるバラストタンクへ
適用した場合に、補修塗装や再塗装といった保守費用を
大幅に削減することができ、産業上その貢献度は極めて
大である。EFFECT OF THE INVENTION The marine steel material of the present invention has excellent coating film damage resistance and greatly reduces maintenance costs such as repair painting and repainting when applied to a ballast tank in a severely corrosive environment. The industrial contribution is extremely large.
Claims (3)
とを特徴とする塗膜寿命性に優れた船舶用鋼材。1. In mass%, C: 0.001 to 0.025%, Si: 0.60% or less, Mn: 0.10 to 3.0%, P: 0.030% or less, S: 0.01% or less, Al: 0.10% or less, Ni: 0.1 Ship steel with excellent coating life, characterized in that it contains up to 4.0% and Cu: 0.1% or less, with the balance being Fe and inevitable impurities.
％で、 Mo：0.05〜0.5 ％、 Co：0.05〜0.5 ％、 Ｗ：0.05〜0.5 ％および Sb：0.05〜0.5 ％ のうちから選んだ１種または２種以上を含有する組成に
なる塗膜寿命性に優れた船舶用鋼材。2. The steel material according to claim 1, further selected from the group consisting of Mo: 0.05 to 0.5%, Co: 0.05 to 0.5%, W: 0.05 to 0.5%, and Sb: 0.05 to 0.5% in mass%. A marine steel material having a coating film life property having a composition containing one or more kinds.
らに質量％で、 Nb：0.005 〜0.20％、 Ｖ：0.005 〜0.20％、 Ti：0.005 〜0.20％、 REM：0.02％以下、 Ca：0.005 ％以下および Ｂ：0.0003〜0.0050％ のうちから選んだ１種または２種以上を含有する組成に
なる塗膜寿命性に優れた船舶用鋼材。3. The steel material according to claim 1, wherein the steel material further comprises, by mass%, Nb: 0.005 to 0.20%, V: 0.005 to 0.20%, Ti: 0.005 to 0.20%, REM: 0.02% or less, Ca: 0.005% or less. % Or less and B: 0.0003 to 0.0050%.
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|---|---|---|---|
| JP2001066258A JP4483107B2 (en) | 2001-03-09 | 2001-03-09 | Marine steel with excellent coating life |
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| JP4483107B2 JP4483107B2 (en) | 2010-06-16 |
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