JP5396758B2 - Hot-rolled section steel for ship ballast tank and manufacturing method thereof - Google Patents

Hot-rolled section steel for ship ballast tank and manufacturing method thereof Download PDF

Info

Publication number
JP5396758B2
JP5396758B2 JP2008178598A JP2008178598A JP5396758B2 JP 5396758 B2 JP5396758 B2 JP 5396758B2 JP 2008178598 A JP2008178598 A JP 2008178598A JP 2008178598 A JP2008178598 A JP 2008178598A JP 5396758 B2 JP5396758 B2 JP 5396758B2
Authority
JP
Japan
Prior art keywords
mass
steel
hot
corrosion resistance
ship
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.)
Active
Application number
JP2008178598A
Other languages
Japanese (ja)
Other versions
JP2009052136A (en
Inventor
達己 木村
伸一 鈴木
伸夫 鹿内
一貴 小林
和彦 塩谷
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
JFE Steel Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by JFE Steel Corp filed Critical JFE Steel Corp
Priority to JP2008178598A priority Critical patent/JP5396758B2/en
Priority to KR1020127033613A priority patent/KR20130004605A/en
Priority to KR1020107001564A priority patent/KR101241935B1/en
Priority to PCT/JP2008/063710 priority patent/WO2009017177A1/en
Priority to CN2008801004873A priority patent/CN101772583B/en
Priority to TW097128385A priority patent/TWI391499B/en
Publication of JP2009052136A publication Critical patent/JP2009052136A/en
Application granted granted Critical
Publication of JP5396758B2 publication Critical patent/JP5396758B2/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/009—Pearlite

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Metal Rolling (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)

Description

本発明は、石炭船や鉱石船、鉱炭兼用船、原油タンカー、ＬＰＧ船、ＬＮＧ船、ケミカルタンカー、コンテナ船、ばら積み船、木材専用船、チップ専用船、冷凍運搬船、自動車専用船、重量物船、ＲＯＲＯ船、石灰石専用船、セメント専用船等に用いられる船舶用形鋼に関し、特に、海水による厳しい腐食環境下にあるバラストタンクの縦通材（ロンジ材）等に用いられる船舶のバラストタンク用熱間圧延形鋼とその製造方法に関するものである。ここで、縦通材（ロンジ材）等に用いられる船舶のバラストタンク用熱間圧延形鋼とは、具体的には、熱間圧延によって成形された等辺山形鋼、不等辺山形鋼、不等辺不等厚山形鋼、溝形鋼、球平形鋼、Ｔ形鋼などをいう。 The present invention includes a coal ship, an ore ship, a coal mine ship, a crude oil tanker, an LPG ship, an LNG ship, a chemical tanker, a container ship, a bulk carrier, a timber ship, a chip ship, a refrigeration carrier ship, an automobile ship, a heavy article ship, RORO vessels, limestone dedicated ships relates marine section steel used in the cement dedicated ships, etc., particularly, ballast tanks of ships used for stringer ballast tanks under severe corrosive environment due to seawater (longitudinals material) etc. The present invention relates to a hot-rolled section steel and a manufacturing method thereof. Here, the hot-rolled shape steel for ship ballast tanks used for longitudinal materials (longi materials), etc., specifically, equilateral mountain shape steel, unequal side angle shape steel, unequal sides formed by hot rolling Non-uniform thick angle steel, grooved steel, spherical flat steel, T-shaped steel, etc.

船舶のバラストタンクは、積荷がない時に、海水を注入して船舶の安定航行を可能とする役目を担うものであるため、非常に厳しい腐食環境下におかれている。そのため、バラストタンクに用いられる鋼材の防食には、通常、エポキシ樹脂塗料による防食塗膜の形成と電気防食とが併用されている。   The ship's ballast tank is in a very severe corrosive environment because it plays the role of injecting seawater to enable stable navigation of the ship when there is no cargo. For this reason, formation of an anticorrosion coating film using an epoxy resin paint and cathodic protection are usually used in combination for corrosion protection of steel materials used in ballast tanks.

しかし、それらの防食対策を講じても、バラストタンクの腐食環境は依然として厳しい状態にある。すなわち、バラストタンクに海水を注入している場合には、海水に完全に浸されている部分は、電気防食が機能するため、腐食を抑えることができる。しかし、バラストタンクの最上部付近、特に上甲板の裏側は、海水に漬かることがなく、海水の飛沫のみを浴びる状態におかれている。そのため、この部位では、電気防食が機能しない。さらに、この部位は、太陽光によって鋼板温度が上昇するため、より厳しい腐食環境となる。一方、バラストタンクに海水が注入されていない場合には、電気防食が全く働かないため、残留付着塩分によって、激しい腐食を受ける。   However, even if these anticorrosion measures are taken, the corrosive environment of the ballast tank is still severe. That is, when seawater is injected into the ballast tank, the portion that is completely immersed in the seawater functions as anticorrosion, and therefore 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 immersed in seawater and is in a state where it is exposed to only seawater splashes. Therefore, cathodic protection does not function at this site. Furthermore, this part becomes a more severe corrosive environment because the steel plate temperature is increased by sunlight. On the other hand, when seawater is not injected into the ballast tank, since the anticorrosion does not work at all, it is severely corroded by residual adhered salt.

そのため、上記のような激しい腐食環境下にあるバラストタンクの防食塗膜の寿命は、一般に約１０年と言われており、船舶の寿命（約２０年）の半分程度である。従って、残りの１０年間は、補修塗装等の処理を施すことよって、耐食性を維持しているのが実情である。しかし、バラストタンクの腐食環境は非常に厳しいものがあるため、補修塗装を行ってもその効果を長時間持続させるのは難しい。また、補修塗装は、狭い空間での作業となるため、作業環境としては好ましいものではない。そこで、補修塗装までの期間をできる限り延長すると共に、作業負荷を軽減できる耐食性に優れた鋼材の開発が望まれている。   Therefore, it is generally said that the anticorrosive coating film of the ballast tank under the severe corrosive environment as described above has a life of about 10 years, which is about half the life of the ship (about 20 years). Therefore, in the remaining 10 years, the actual situation is that the corrosion resistance is maintained by performing a treatment such as repair painting. However, since the corrosive environment of the ballast tank is very severe, it is difficult to maintain the effect for a long time even if repair coating is performed. In addition, since repair painting is performed in a narrow space, it is not preferable as a work environment. Therefore, it is desired to develop a steel material with excellent corrosion resistance that can extend the period until repair coating as much as possible and reduce the work load.

そこで、バラストタンク等、厳しい腐食環境下で用いられる鋼材自体の耐食性を向上する技術が幾つか提案されている。たとえば、特許文献１には、Ｃ：０．２０ｍａｓｓ％以下の鋼に、耐食性改善元素として、Ｃｕ：０．０５〜０．５０ｍａｓｓ％、Ｗ：０．０１〜０．０５ｍａｓｓ％未満を添加し、さらに、Ｇｅ，Ｓｎ，Ｐｂ，Ａｓ，Ｓｂ，Ｂｉ，ＴｅおよびＢｅのうちの１種または２種以上を０．０１〜０．２ｍａｓｓ％添加した耐食低合金鋼が開示されている。また、特許文献２には、Ｃ：０．２０ｍａｓｓ％以下の鋼材に、耐食性改善元素として、Ｃｕ：０．０５〜０．５０ｍａｓｓ％、Ｗ：０．０５〜０．５ｍａｓｓ％を添加し、さらに、Ｇｅ，Ｓｎ，Ｐｂ，Ａｓ，Ｓｂ，Ｂｉ，ＴｅおよびＢｅのうちの１種もしくは２種以上を０．０１〜０．２ｍａｓｓ％添加した耐食性低合金鋼が開示されている。また、特許文献３には、Ｃ：０．１５ｍａｓｓ％以下の鋼に、Ｃｕ：０．０５〜０．１５ｍａｓｓ％未満、Ｗ：０．０５〜０．５ｍａｓｓ％を添加した耐食性低合金鋼が開示されている。   Thus, several techniques for improving the corrosion resistance of steel materials themselves used in severe corrosive environments such as ballast tanks have been proposed. For example, in Patent Document 1, Cu: 0.05 to 0.50 mass%, W: 0.01 to less than 0.05 mass%, as a corrosion resistance improving element, is added to steel of C: 0.20 mass% or less, Furthermore, a corrosion-resistant low alloy steel is disclosed in which one or more of Ge, Sn, Pb, As, Sb, Bi, Te and Be are added in an amount of 0.01 to 0.2 mass%. Further, in Patent Document 2, Cu: 0.05 to 0.50 mass%, W: 0.05 to 0.5 mass%, as a corrosion resistance improving element, is added to a steel material having C: 0.20 mass% or less, and , Ge, Sn, Pb, As, Sb, Bi, Te, and Be are disclosed corrosion resistant low alloy steel added with 0.01 to 0.2 mass% of one or more of them. Patent Document 3 discloses a corrosion-resistant low alloy steel obtained by adding Cu: less than 0.05 to 0.15 mass% and W: 0.05 to 0.5 mass% to steel having C: 0.15 mass% or less. Has been.

また、特許文献４には、Ｃ：０．１５ｍａｓｓ％以下の鋼に、耐食性改善元素として、Ｐ：０．０３〜０．１０ｍａｓｓ％、Ｃｕ：０．１〜１．０ｍａｓｓ％、Ｎｉ：０．２〜１．０ｍａｓｓ％を添加した低合金耐食鋼材に、タールエポキシ塗料、ピュアエポキシ塗料、無溶剤型エポキシ塗料、ウレタン塗料等の防食塗料を塗布し、樹脂被覆したバラストタンクが開示されている。この技術は、鋼材自身の耐食性向上により防食塗装の寿命を延長し、船舶の使用期間である２０〜３０年に亘ってメンテナンスフリー化を実現しようとするものである。   In Patent Document 4, C: 0.15 mass% or less of steel, P: 0.03-0.10 mass%, Cu: 0.1-1.0 mass%, Ni: 0.0. A ballast tank is disclosed in which an anticorrosion paint such as a tar epoxy paint, a pure epoxy paint, a solventless epoxy paint, and a urethane paint is applied to a low alloy corrosion resistant steel material to which 2 to 1.0 mass% is added, and is coated with a resin. This technology intends to extend the life of the anticorrosion coating by improving the corrosion resistance of the steel material itself, and to realize maintenance-free over 20 to 30 years, which is the use period of the ship.

また、特許文献５には、Ｃ：０．１５ｍａｓｓ％以下の鋼に、耐食性改善元素として、Ｃｒ：０．２〜５ｍａｓｓ％を添加して耐食性を向上し、船舶のメンテナンスフリー化を実現しようとする提案がなされている。さらに、特許文献６には、Ｃ：０．１５ｍａｓｓ％以下の鋼に、耐食性改善元素として、Ｃｒ：０．２〜５ｍａｓｓ％を添加した鋼材を構成材料として使用すると共に、バラストタンク内部の酸素ガス濃度を大気中の値に対して０．５以下の比率とすることを特徴とするバラストタンクの防食方法が提案されている。   In Patent Document 5, an attempt is made to improve the corrosion resistance by adding 0.2% to 5% by mass as a corrosion resistance improving element to C: 0.15 mass% or less steel, thereby realizing a maintenance-free ship. Proposals have been made. Further, Patent Document 6 uses a steel material in which Cr: 0.2 to 5 mass% is added as a corrosion resistance improving element to steel of C: 0.15 mass% or less as a constituent material, and oxygen gas inside the ballast tank. An anticorrosion method for a ballast tank has been proposed in which the concentration is a ratio of 0.5 or less with respect to the value in the atmosphere.

また、特許文献７には、Ｃ：０．１ｍａｓｓ％以下の鋼に、Ｃｒ：０．５〜３．５ｍａｓｓ％を添加することで耐食性を向上し、船舶のメンテナンスフリー化を実現しようとする提案がなされている。さらに、特許文献８には、Ｃ：０．００１〜０．０２５ｍａｓｓ％の鋼に、Ｎｉ：０．１〜４．０ｍａｓｓ％を添加することで、耐塗膜損傷性を向上し、補修塗装などの保守費用を軽減する船舶用鋼材が開示されている。   Further, Patent Document 7 proposes to improve corrosion resistance by adding Cr: 0.5 to 3.5 mass% to steel of C: 0.1 mass% or less, and to realize a maintenance-free ship. Has been made. Furthermore, in Patent Document 8, by adding Ni: 0.1-4.0 mass% to C: 0.001-0.025 mass% steel, coating film damage resistance is improved, repair coating, etc. Marine steel materials that reduce maintenance costs are disclosed.

また、特許文献９には、Ｃ：０．０１〜０．２５ｍａｓｓ％の鋼に、Ｃｕ：０．０１〜２．００ｍａｓｓ％、Ｍｇ：０．０００２〜０．０１５０ｍａｓｓ％を添加することで、船舶外板、バラストタンク、カーゴオイルタンク、鉱炭石カーゴホールド等の使用環境において耐食性を有する船舶用鋼が開示されている。さらに、特許文献１０には、Ｃ：０．００１〜０．２ｍａｓｓ％の鋼において、Ｍｏ，ＷとＣｕとを複合添加し、不純物であるＰ，Ｓの添加量を限定することにより、原油油槽で生じる全面腐食、局部腐食を抑制した鋼が開示されている。   Moreover, in patent document 9, it is a ship by adding Cu: 0.01-2.00 mass% and Mg: 0.0002-0.0150 mass% to C: 0.01-0.25 mass% steel. Steels for ships having corrosion resistance in use environments such as an outer plate, a ballast tank, a cargo oil tank, and a coal ore cargo hold are disclosed. Further, Patent Document 10 discloses a crude oil tank by adding Mo, W and Cu in C: 0.001 to 0.2 mass% steel and limiting the amount of P and S which are impurities. Steel that suppresses general corrosion and local corrosion that occur in JIS is disclosed.

しかしながら、上記特許文献１〜３には、バラストタンク等を構成する鋼材に通常塗布されているジンクエポキシ樹脂塗料等の塗膜存在下での耐食性については十分な検討がなされておらず、従って、上記のような塗膜存在下での耐食性については、さらなる検討の必要がある。   However, in Patent Documents 1 to 3 above, sufficient examination has not been made on the corrosion resistance in the presence of a coating film such as a zinc epoxy resin paint that is usually applied to a steel material constituting a ballast tank or the like. Further investigation is necessary for the corrosion resistance in the presence of the coating film as described above.

また、特許文献４の鋼材は、下地金属の耐食性を向上させるために、Ｐを０．０３〜０．１０ｍａｓｓ％と比較的多量に添加しており、溶接性および溶接部靭性の面からは問題がある。また、特許文献５および特許文献６の鋼材は、Ｃｒを０．２〜５ｍａｓｓ％含有し、また、特許文献７の鋼材は、Ｃｒを０．５〜３．５ｍａｓｓ％と比較的多く含有しているため、いずれも溶接性および溶接部靭性に問題がある他、製造コストが高くなるという問題がある。また、特許文献８の鋼材は、Ｃ含有量が低く、Ｎｉ含有量が高いため、製造コストが高くなるという問題がある。   Further, in the steel material of Patent Document 4, P is added in a relatively large amount of 0.03 to 0.10 mass% in order to improve the corrosion resistance of the base metal, which is problematic from the viewpoint of weldability and weld toughness. There is. Moreover, the steel materials of Patent Literature 5 and Patent Literature 6 contain 0.2 to 5 mass% of Cr, and the steel material of Patent Literature 7 contains relatively large amount of Cr to 0.5 to 3.5 mass%. Therefore, both have problems in weldability and weld zone toughness, as well as the problem of increased manufacturing costs. Moreover, since the steel material of patent document 8 has low C content and high Ni content, there exists a problem that manufacturing cost becomes high.

さらに、特許文献９の鋼材は、Ｍｇの添加を必須としているため、製鋼歩留りが安定せず、鋼材の機械的特性も安定しないという問題がある。さらに、特許文献１０の鋼材は、原油油槽内というＨ２Ｓが存在する環境下で使用される耐食鋼であり、Ｈ２Ｓが存在しないバラストタンクでの耐食性は不明である。さらに、バラストタンク用鋼材に一般的に使用されているジンクプライマーが塗布された状態での耐食性については検討がなされていない。したがって、バラストタンクに用いるには、さらなる耐食性の検討が必要である。
特開昭４８−０５０９２１号公報 特開昭４８−０５０９２２号公報 特開昭４８−０５０９２４号公報 特開平０７−０３４１９７号公報 特開平０７−０３４１９６号公報 特開平０７−０３４２７０号公報 特開平０７−３１０１４１号公報 特開２００２−２６６０５２号公報 特開２０００−０１７３８１号公報 特開２００４−２０４３４４号公報 Furthermore, since the steel material of Patent Document 9 requires the addition of Mg, there is a problem that the steel making yield is not stable and the mechanical properties of the steel material are not stable. Furthermore, the steel material of patent document 10 is a corrosion resistant steel used in an environment where H 2 S exists in a crude oil tank, and the corrosion resistance in a ballast tank without H 2 S is unknown. Furthermore, the corrosion resistance in the state in which the zinc primer generally used for the steel for ballast tanks is applied has not been studied. Therefore, further examination of corrosion resistance is necessary for use in a ballast tank.
JP-A-48-050921 JP 48-050922 A JP-A-48-050924 Japanese Patent Application Laid-Open No. 07-034197 Japanese Patent Application Laid-Open No. 07-034196 Japanese Patent Application Laid-Open No. 07-034270 JP 07-310141 A JP 2002-266052 A JP 2000-017341 A JP 2004-204344 A

一般に、船舶は、厚鋼板や薄鋼板、形鋼、棒鋼等の鋼材を溶接して建造されており、その鋼材の表面には防食塗装が施されている。上記防食塗装は、一次防錆として、ジンクプライマーを塗付し、小組み後あるいは大組み後に、二次塗装（本塗装）として、エポキシ樹脂塗装が施されるのが普通である。したがって、船舶の鋼材表面の大部分は、ジンクプライマーとエポキシ樹脂塗装の２層構造の防食塗装が施されている。また、溶接部は、溶接時の熱によってジンクプライマーが焼失するため、溶接後から本塗装までの間の防錆対策として、ジンクプライマーによる補修塗装（タッチアップ）が施される。しかし、本塗装までの期間が短い場合には、補修塗装を行わないこともある。また、建造後、長年使用した船舶では、上記塗膜が劣化し、防錆塗膜としての機能を十分に果たしていない部分や、塗膜が剥げて鋼板が裸状態になっている部分が存在する。   Generally, a ship is constructed by welding steel materials such as thick steel plates, thin steel plates, shaped steels, and steel bars, and the surface of the steel materials is subjected to anticorrosion coating. The anticorrosion coating is usually applied with a zinc primer as a primary rust prevention, and after a small or large assembly, an epoxy resin coating is applied as a secondary coating (main coating). Therefore, most of the steel surface of the ship is subjected to a two-layer anticorrosion coating of zinc primer and epoxy resin coating. In addition, since the zinc primer is burned off by the heat during welding, the welded portion is subjected to repair coating (touch-up) with the zinc primer as a rust prevention measure from after welding to the main coating. However, if the period until the final coating is short, repair coating may not be performed. In addition, in ships that have been used for many years after construction, there are parts where the above-mentioned coating film deteriorates and the function as a rust-proof coating film is not sufficiently achieved, and the coating film peels off and the steel sheet is in a bare state .

つまり、就航している船舶の鋼材の表面には、ジンクプライマーとエポキシ樹脂塗装の２層の塗装が施されている部分と、エポキシ樹脂塗装のみの部分と、裸状態の部分の３つの状態が存在することになる。したがって、船舶の耐食性を向上させるという目的を達成するためには、それらのいずれの状態においても優れた耐食性を示す船舶用鋼材であることが必要とされる。   In other words, on the surface of the steel material of the ship in service, there are three states: a part with two layers of zinc primer and epoxy resin coating, a part with only epoxy resin coating, and a bare part Will exist. Therefore, in order to achieve the object of improving the corrosion resistance of the ship, it is necessary to be a marine steel material that exhibits excellent corrosion resistance in any of these states.

ところで、船舶に用いられる厚鋼板は、使用鋼材量低減によるコスト削減および安全性確保の観点から、高強度化が進められており、降伏応力ＹＰが３１５ＭＰａ以上で、かつ好ましくは、引張強さＴＳが４４０ＭＰａ以上の高強度材が使用されるようになってきている。厚鋼板の場合、強度と靭性の制御は、制御圧延・加速冷却プロセス（ＴＭＣＰ）の条件を調整することにより達成されるのが一般的である。
一方、バラストタンクのロンジ材等に使用される鋼材、中でも、不等辺不等厚山形鋼やＴ形鋼などの熱間圧延形鋼は、同じ船舶に用いられる厚鋼板などと比較して断面形状・寸法が複雑であるため、強度と靭性の制御方法として、厚鋼板と同様のＴＭＣＰを採用することは困難である。特に、圧延途中での曲がりや反りに配慮しながら、材質の造りこみを行う必要があるため、降伏応力ＹＰが３１５ＭＰａ以上の高強度形鋼とするためには、形鋼独自の製造方法を検討する必要がある。 By the way, thick steel plates used in ships are being increased in strength from the viewpoints of cost reduction and safety ensuring by reducing the amount of steel used, yield stress YP is 315 MPa or more, and preferably tensile strength TS. However, high-strength materials of 440 MPa or higher have been used. In the case of a thick steel plate, strength and toughness are generally controlled by adjusting the conditions of a controlled rolling / accelerated cooling process (TMCP).
On the other hand, steel materials used for ballast tanks such as long steel, especially hot-rolled steel shapes such as unequal unequal thick angle steel and T-shaped steel, have a cross-sectional shape compared to thick steel plates used in the same ship. -Since the dimensions are complicated, it is difficult to adopt TMCP similar to that of thick steel plates as a method for controlling strength and toughness. In particular, considering the bending and warping in the middle of rolling, it is necessary to build the material. Therefore, in order to obtain a high-strength shape steel with a yield stress YP of 315 MPa or more, consider a unique method for producing the shape steel. There is a need to.

そこで、本発明の目的は、船舶のバラストタンク等の厳しい腐食環境下において、塗膜の存在状態に左右されることなく優れた耐食性を発揮して、補修塗装までの期間の延長が可能となり、ひいては補修塗装の作業軽減を図ることができる耐食性に優れるＹＰが３１５ＭＰａ以上の強度を有する縦通材（ロンジ材）等に用いられる船舶のバラストタンク用熱間圧延形鋼（以降、単に「船舶用熱間圧延形鋼」ともいう）を安価に提供することにある。 Therefore, the object of the present invention is to exhibit excellent corrosion resistance without being affected by the presence state of the coating film in a severe corrosive environment such as a ballast tank of a ship, and it is possible to extend the period until repair coating, As a result, it is possible to reduce the work of repair coating. Hot rolled steel for ship ballast tanks (hereinafter referred to simply as “for ship use” ), which is used as a longitudinal material (longi material) with a strength of 315 MPa or more that has excellent corrosion resistance . It is also provided at a low cost.

発明者らは、海水による厳しい腐食環境下でも表面状態（塗膜の存在状態）に左右されることなく優れた耐食性を示すと共に、高強度を有する形鋼の開発に向けて鋭意研究を重ねた。その結果、ＷとＣｒを必須元素として添加し、これにさらに、Ｓｂ，Ｓｎ等の耐食性向上元素を適正範囲で含有させることにより、ジンクプライマーとエポキシ樹脂塗装の２層塗膜状態、エポキシ樹脂塗膜状態および裸状態のいずれの状態においても優れた耐食性を示す船舶用熱間圧延形鋼が得られること、また、生産性や溶接性等を害することなく形鋼の高強度化を図るには、（α＋γ）２相域圧延による加工フェライトの導入が有効であることを見出し、本発明を完成させた。   The inventors have shown excellent corrosion resistance without being influenced by the surface state (existing state of the coating film) even in a severe corrosive environment by seawater, and repeated earnest research toward the development of a shape steel having high strength. . As a result, by adding W and Cr as essential elements, and further adding corrosion resistance improving elements such as Sb and Sn in an appropriate range, a two-layer coating state of zinc primer and epoxy resin coating, epoxy resin coating To obtain a hot-rolled section steel for marine vessels that exhibits excellent corrosion resistance in both the film state and the bare state, and to increase the strength of the shape steel without impairing productivity, weldability, etc. The introduction of processed ferrite by (α + γ) two-phase rolling was found to be effective, and the present invention was completed.

すなわち、本発明は、Ｃ：０．０３〜０．２５ｍａｓｓ％、Ｓｉ：０．０５〜０．５０ｍａｓｓ％、Ｍｎ：０．１〜２．０ｍａｓｓ％、Ｐ：０．０２５ｍａｓｓ％以下、Ｓ：０．０１ｍａｓｓ％以下、Ａｌ：０．００５〜０．１０ｍａｓｓ％、Ｗ：０．０１〜１．０ｍａｓｓ％、Ｃｒ：０．０１ｍａｓｓ％以上０．２０ｍａｓｓ％未満、Ｎ：０．００１〜０．００８ｍａｓｓ％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し、加工フェライトを含むフェライトとパーライト組織とからなるミクロ組織を有する耐食性に優れる船舶のバラストタンク用熱間圧延形鋼である。 That is, the present invention is C: 0.03-0.25 mass%, Si: 0.05-0.50 mass%, Mn: 0.1-2.0 mass%, P: 0.025 mass% or less, S: 0 .01 mass% or less, Al: 0.005 to 0.10 mass%, W: 0.01 to 1.0 mass%, Cr: 0.01 mass% or more and less than 0.20 mass%, N: 0.001 to 0.008 mass% Is a hot-rolled section steel for ballast tanks of ships , which has a component composition consisting of Fe and inevitable impurities, and has a microstructure composed of ferrite containing processed ferrite and a pearlite structure, and is excellent in corrosion resistance.

本発明の船舶のバラストタンク用熱間圧延形鋼は、上記成分組成に加えてさらに、下記Ａ〜Ｅ群のうちの少なくとも１群に属する成分を含有することが好ましい。
記
Ａ群；Ｓｂ：０．００１〜０．３ｍａｓｓ％およびＳｎ：０．００１〜０．３ｍａｓｓ％のうちから選ばれる１種または２種
Ｂ群；Ｍｏ：０．０１〜０．５ｍａｓｓ％およびＣｏ：０．０１〜１．０ｍａｓｓ％のうちから選ばれる１種または２種
Ｃ群；Ｎｂ：０．００１〜０．１ｍａｓｓ％、Ｔｉ：０．００１〜０．１ｍａｓｓ％、Ｚｒ：０．００１〜０．１ｍａｓｓ％およびＶ：０．００２〜０．２ｍａｓｓ％のうちから選ばれる１種または２種以上
Ｄ群；Ｂ：０．０００２〜０．００３ｍａｓｓ％
Ｅ群；Ｃａ：０．０００２〜０．０１ｍａｓｓ％、ＲＥＭ：０．０００２〜０．０１５ｍａｓｓ％およびＹ：０．０００１〜０．１ｍａｓｓ％のうちから選ばれる１種または２種以上 In addition to the above component composition, the hot rolled steel bar for ship ballast tank of the present invention preferably further contains a component belonging to at least one of the following groups A to E.
Group A; Sb: 0.001 to 0.3 mass% and Sn: one or two types selected from 0.001 to 0.3 mass% ; Group B ; Mo: 0.01 to 0.5 mass% and Co: 1 or two or C group selected from among 0.01~1.0mass%; Nb: 0.001~0.1mass%, Ti: 0.001~0.1mass%, Zr: 0.001 -0.1 mass% and V: 1 type or 2 or more types chosen from 0.002-0.2 mass%; B: 0.0002-0.003mass%
Group E; Ca: 0.0002 to 0.01 mass%, REM: 0.0002 to 0.015 mass%, and Y: 0.0001 to 0.1 mass%, or one or more selected from the group

また、本発明の船舶のバラストタンク用熱間圧延形鋼は、形鋼表面に、エポキシ樹脂塗膜、ジンクプライマー塗膜およびジンクプライマー塗膜とエポキシ樹脂塗膜のいずれかを有することが好ましい。 Moreover, it is preferable that the hot rolled shape steel for ship ballast tanks of the present invention has any one of an epoxy resin coating, a zinc primer coating, a zinc primer coating and an epoxy resin coating on the surface of the shape steel.

また、本発明は、上記船舶のバラストタンク用熱間圧延形鋼を製造するに当たり、上記成分組成を有する鋼素材を１０００〜１３５０℃に加熱後、Ａｒ３温度以下での累積圧下率を１０〜８０％、圧延仕上温度を（Ａｒ３−３０℃）〜（Ａｒ３−１８０℃）とする熱間圧延を施し、その後、放冷することを特徴とする船舶のバラストタンク用熱間圧延形鋼の製造方法である。 Further, in the present invention, in manufacturing the hot rolled steel for ballast tanks of the ship , the steel material having the above component composition is heated to 1000 to 1350 ° C., and the cumulative reduction ratio at Ar 3 temperature or less is 10 to 10%. Hot-rolled section steel for ballast tanks of ships , characterized by being hot-rolled with 80% rolling finishing temperature of (Ar 3 -30 ° C.) to (Ar 3 -180 ° C.) and then left to cool. It is a manufacturing method.

本発明の上記製造方法は、Ａｒ３温度以下での熱間圧延を、形鋼断面内の温度差を５０℃以内として行うことが好ましい。 In the production method of the present invention, it is preferable to perform hot rolling at an Ar 3 temperature or less with a temperature difference in the cross section of the shaped steel within 50 ° C.

本発明によれば、高強度でかつ海水による厳しい腐食環境下でも優れた耐食性を有する船舶用熱間圧延形鋼を安価に提供することができる。また、本発明の形鋼は、耐食性に優れるので、船舶の補修塗装までの期間の延長および補修塗装の作業負荷軽減に大きく寄与することができる。   According to the present invention, it is possible to provide a marine hot-rolled section steel having high strength and excellent corrosion resistance even in a severe corrosive environment with seawater at a low cost. In addition, since the shape steel of the present invention is excellent in corrosion resistance, it can greatly contribute to the extension of the period until the repair coating of the ship and the reduction of the work load of the repair coating.

発明者らは、就航している船舶に用いられている鋼材に存在する３つ状態、即ち、ジンクプライマーとエポキシ樹脂塗膜の２層塗膜を有する状態とエポキシ樹脂塗膜のみの状態および裸状態のいずれにおいても、優れた耐食性を有する船舶用熱間圧延形鋼を開発するため、以下の実験を行った。   The inventors of the present invention have three states existing in a steel material used in a ship in service, that is, a state having a two-layer coating of a zinc primer and an epoxy resin coating, a state of only an epoxy resin coating, and a bare state. In any of the states, the following experiment was conducted to develop a marine hot-rolled section steel having excellent corrosion resistance.

種々の合金元素を添加した鋼を実験室的に溶製し、熱間圧延して板厚が５ｍｍの熱延板とし、それらの熱延板から５ｍｍｔ×１００ｍｍＷ×２００ｍｍＬまたは５ｍｍｔ×５０ｍｍＷ×１５０ｍｍＬの試験片を採取し、その試験片の表面にショットブラストして表面のスケールや油分を除去したのち、下記の３種類の表面処理を施した暴露試験用試験片を作製した。
条件Ａ：試験片表面に、ジンクプライマー（膜厚約１５μｍ）とタールエポキシ樹脂塗料（膜厚約１００μｍ）の２層被膜を形成
条件Ｂ：試験片表面に、タールエポキシ樹脂塗料（膜厚約１００μｍ）の単層被膜を形成
条件Ｃ：試験片表面にショットブラストしたままの裸状態（防食被膜なし） Steels added with various alloying elements are melted in the laboratory and hot rolled to form hot rolled sheets having a thickness of 5 mm. From these hot rolled sheets, 5 mmt × 100 mmW × 200 mmL or 5 mmt × 50 mmW × 150 mmL A test piece was collected and shot blasted on the surface of the test piece to remove the scale and oil on the surface, and then a test piece for an exposure test subjected to the following three types of surface treatment was prepared.
Condition A: Two-layer coating of zinc primer (film thickness of about 15 μm) and tar epoxy resin paint (film thickness of about 100 μm) is formed on the surface of the test piece Condition B: Tar epoxy resin paint (film thickness of about 100 μm) on the surface of the test piece ) Condition C: Bare state with shot blasting on the specimen surface (no anticorrosion coating)

その後、これらの試験片を、実船バラストタンクの上甲板裏側の腐食環境を模擬した、（３５℃、５ｍａｓｓ％ＮａＣｌ溶液噴霧×２ｈｒ）→（６０℃、ＲＨ５ｍａｓｓ％×４ｈｒ）→（５０℃、ＲＨ９５ｍａｓｓ％×２ｈｒ）を１サイクルとし、これを１３２サイクル行う塩水噴霧乾湿繰返し腐食試験に供した。そして、耐食性は、塗膜を有する条件ＡおよびＢの試験片については、試験前、塗膜の上からカッターナイフで地鉄表面まで達する８０ｍｍ長さのスクラッチ疵を一文字状に付与しておき、試験後、スクラッチ疵の周囲に発生した塗脚膨れ面積を測定することで、また、塗膜を有しない条件Ｃの試験片については、試験後、脱錆し、その脱錆した試験片重量と腐食試験前の試験片重量の差（減少量）から平均板厚減少量を算出することで評価した。   Then, these test pieces were simulated the corrosive environment on the upper deck side of the actual ballast tank, (35 ° C., 5 mass% NaCl solution spray × 2 hr) → (60 ° C., RH 5 mass% × 4 hr) → (50 ° C., RH95 mass% × 2 hr) was taken as one cycle, and this was subjected to a salt spray wet and dry repeated corrosion test for 132 cycles. And, for the corrosion resistance, for the test pieces of the conditions A and B having a coating film, before the test, an 80 mm length scratch scissor that reaches the surface of the iron core with a cutter knife from the top of the coating film is given in a single character, After the test, by measuring the area of the swollen swelled around the scratching flaw, and for the test piece of the condition C having no coating film, after the test, derusting, Evaluation was made by calculating the average thickness reduction amount from the difference (decrease amount) in the weight of the specimen before the corrosion test.

上記腐食試験の結果から、各合金元素の耐食性向上効果を、試験片表面の塗膜条件ごとに纏めて表１に示した。この結果を簡単に述べると、
１）条件Ａ（ジンクプライマー＋タールエポキシ樹脂塗装の２層塗膜）の場合；耐食性の向上に最も有効な元素はＣｒであり、次いでＷ、次いでＳｂである。
２）条件Ｂ（タールエポキシ樹脂塗膜の１層のみ）の場合；耐食性の向上に最も有効な元素はＷであり、次いでＳｂ，Ｓｎである。
３）条件Ｃ（裸状態）の場合；耐食性の向上に最も有効な元素はＷであり、次いでＳｂ，Ｓｎである。
４）ＷとＣｒを複合添加すると、条件Ａでの耐食性が単独含有の場合より向上し、Ｓｂ，Ｓｎを追加添加すると、条件Ａだけでなく、条件Ｂ，Ｃでも顕著な改善効果を奏する。
５）Ｍｏの添加は、条件Ａ，Ｂ，Ｃとも、耐食性をやや向上し、Ｃｕ，Ｎｉ，Ｃｏは、条件Ａ，Ｃで、耐食性をやや向上する。 From the results of the corrosion test, Table 1 shows the effect of improving the corrosion resistance of each alloy element for each coating film condition on the surface of the test piece. In short, the result is:
1) In the case of condition A (zinc primer + tar epoxy resin coated two-layer coating film); the most effective element for improving corrosion resistance is Cr, then W, and then Sb.
2) In the case of condition B (only one layer of the tar epoxy resin coating); W is the most effective element for improving corrosion resistance, and then Sb and Sn.
3) In the case of condition C (bare state); the most effective element for improving the corrosion resistance is W, and then Sb and Sn.
4) When W and Cr are added in combination, the corrosion resistance under the condition A is improved as compared with the case of containing alone, and when Sb and Sn are additionally added, not only the condition A but also the conditions B and C have a remarkable improvement effect.
5) Addition of Mo slightly improves the corrosion resistance in both conditions A, B, and C, and Cu, Ni, and Co slightly improve the corrosion resistance in conditions A and C.

Figure 0005396758
Figure 0005396758

上記試験の結果を基に、本発明では、耐食性を向上する基本元素としてＷとＣｒを複合添加する成分系を採用し、さらに、耐食性が要求される場合には、Ｓｂ，Ｓｎから選ばれる１種または２種を追加して添加する成分設計を採用することとした。そして、さらに優れた耐食性を要求される場合には、Ｃｕ，Ｎｉ，Ｍｏ，Ｃｏから選ばれる１種または２種以上を添加することとした。   Based on the results of the above test, in the present invention, a component system in which W and Cr are added together as a basic element for improving corrosion resistance is adopted, and when corrosion resistance is required, 1 is selected from Sb and Sn. It was decided to adopt a component design in which seeds or two kinds were added in addition. When more excellent corrosion resistance is required, one or more selected from Cu, Ni, Mo, and Co are added.

次に、本発明の耐食性に優れる船舶用熱間圧延形鋼が有すべき成分組成について説明する。
Ｃ：０．０３〜０．２５ｍａｓｓ％
Ｃは、鋼の強度を高めるのに有効な元素であり、本発明では所望の強度を得るために０．０３ｍａｓｓ％以上含有させる必要がある。一方、０．２５ｍａｓｓ％を超える添加は、溶接熱影響部（ＨＡＺ）の靭性を低下させる。よって、Ｃ含有量は０．０３〜０．２５ｍａｓｓ％の範囲とする。なお、後述する加工フェライトによって強度と靭性を両立させる観点からは、Ｃは、０．０５〜０．２０ｍａｓｓ％の範囲が好ましい。 Next, the component composition that the marine hot-rolled section steel excellent in corrosion resistance of the present invention should have will be described.
C: 0.03-0.25 mass%
C is an element effective for increasing the strength of steel, and in the present invention, it is necessary to contain 0.03 mass% or more in order to obtain a desired strength. On the other hand, addition exceeding 0.25 mass% lowers the toughness of the weld heat affected zone (HAZ). Therefore, the C content is in the range of 0.03 to 0.25 mass%. In addition, C is preferably in the range of 0.05 to 0.20 mass% from the viewpoint of achieving both strength and toughness by the processed ferrite described later.

Ｓｉ：０．０５〜０．５０ｍａｓｓ％
Ｓｉは、脱酸剤として、また、鋼の強度を高めるために添加される元素であり、本発明では、０．０５ｍａｓｓ％以上添加する。しかし、０．５０ｍａｓｓ％を超える添加は、鋼の靭性を低下させるので、Ｓｉの上限は０．５０ｍａｓｓ％とする。 Si: 0.05-0.50 mass%
Si is an element added as a deoxidizer and to increase the strength of steel. In the present invention, it is added in an amount of 0.05 mass% or more. However, since addition exceeding 0.50 mass% lowers the toughness of steel, the upper limit of Si is made 0.50 mass%.

Ｍｎ:０．１〜２．０ｍａｓｓ％
Ｍｎは、熱間脆性を防止し、鋼の強度を高める効果がある元素であり、０．１ｍａｓｓ％以上添加する。しかし、Ｍｎの２．０ｍａｓｓ％を超える添加は、鋼の靭性および溶接性を低下させるため、上限は２．０ｍａｓｓ％とする。好ましくは、０．５〜１．６ｍａｓｓ％の範囲である。 Mn: 0.1 to 2.0 mass%
Mn is an element that has the effect of preventing hot brittleness and increasing the strength of steel, and is added in an amount of 0.1 mass% or more. However, the addition of Mn exceeding 2.0 mass% lowers the toughness and weldability of the steel, so the upper limit is made 2.0 mass%. Preferably, it is in the range of 0.5 to 1.6 mass%.

Ｐ：０．０２５ｍａｓｓ％以下
Ｐは、鋼の母材靭性、溶接性および溶接部靭性を低下させる有害な元素であり、できるかぎり低減するのが好ましい。特に、Ｐの含有量が０．０２５ｍａｓｓ％を超えると、母材靭性および溶接部靭性の低下が大きくなる。よって、Ｐは０．０２５ｍａｓｓ％以下とする。好ましくは、０．０１４ｍａｓｓ％以下である。 P: 0.025 mass% or less P is a harmful element that lowers the base metal toughness, weldability and weld zone toughness of steel, and is preferably reduced as much as possible. In particular, when the P content exceeds 0.025 mass%, the deterioration of the base metal toughness and the welded portion toughness increases. Therefore, P is set to 0.025 mass% or less. Preferably, it is 0.014 mass% or less.

Ｓ：０．０１ｍａｓｓ％以下
Ｓは、鋼の靭性および溶接性を低下させる有害な元素であるので、できるかぎり低減することが好ましく、本発明では、０．０１ｍａｓｓ％以下とする。 S: 0.01 mass% or less Since S is a harmful element that lowers the toughness and weldability of steel, it is preferably reduced as much as possible. In the present invention, it is 0.01 mass% or less.

Ａｌ：０．００５〜０．１０ｍａｓｓ％
Ａｌは、脱酸剤として添加される元素であり、０．００５ｍａｓｓ％以上添加する必要がある。しかし、０．１０ｍａｓｓ％を超えて添加すると、地鉄の腐食により溶出したＡｌ３＋により、地鉄表面のｐＨが低下し、耐食性が低下するので、Ａｌ含有量の上限は０．１０ｍａｓｓ％とする。 Al: 0.005-0.10 mass%
Al is an element added as a deoxidizer, and it is necessary to add 0.005 mass% or more. However, if it is added in excess of 0.10 mass%, the pH of the surface of the iron core is lowered due to Al 3+ eluted by the corrosion of the iron and the corrosion resistance is lowered, so the upper limit of the Al content is 0.10 mass%. .

Ｗ：０．０１〜１．０ｍａｓｓ％
Ｗは、上述したように、ジンクプライマーとエポキシ樹脂塗膜の存在下での鋼の耐食性を向上するが、エポキシ樹脂塗膜存在下および裸の状態での耐食性を顕著に向上する効果がある。したがって、本発明においては、耐食性向上元素として最も重要な元素の１つである。上記効果は、Ｗ：０．０１ｍａｓｓ％以上の添加で発現する。しかし、添加量が１．０ｍａｓｓ％超えると、上記効果は飽和してしまう。よって、Ｗの含有量は０．０１〜１．０ｍａｓｓ％の範囲とする。好ましくは０．０２〜０．３ｍａｓｓ％の範囲である。さらに好ましくは、０．０２〜０．２ｍａｓｓ％の範囲である。 W: 0.01-1.0 mass%
As described above, W improves the corrosion resistance of steel in the presence of the zinc primer and the epoxy resin coating film, but has the effect of significantly improving the corrosion resistance in the presence of the epoxy resin coating film and in the bare state. Therefore, in the present invention, it is one of the most important elements as an element for improving corrosion resistance. The above effect is manifested by adding W: 0.01 mass% or more. However, if the addition amount exceeds 1.0 mass%, the above effect is saturated. Therefore, the W content is in the range of 0.01 to 1.0 mass%. Preferably it is the range of 0.02-0.3 mass%. More preferably, it is the range of 0.02-0.2 mass%.

Ｗが、上記耐食性向上効果を有する理由は、鋼板の腐食に伴って生成する錆の中にＷＯ４ ２−が生成され、このＷＯ４ ２−の存在によって、塩化物イオンの鋼板表面への侵入が抑制されることの他に、鋼板表面のアノード部などのｐＨが低下した部位に難溶性のＦｅＷＯ４が生成され、このＦｅＷＯ４の存在によっても、塩化物イオンの鋼板表面への侵入が抑制される結果、鋼の腐食が効果的に抑制されるからである。また、ＷＯ４ ２−のインヒビター作用によっても、鋼の腐食が抑制される。 The reason why W has the above-described effect of improving corrosion resistance is that WO 4 2− is generated in the rust generated along with corrosion of the steel sheet, and the presence of this WO 4 2− causes chloride ions to enter the steel sheet surface. In addition to being suppressed, poorly soluble FeWO 4 is generated at sites where the pH is lowered, such as the anode portion on the steel sheet surface, and the presence of this FeWO 4 also suppresses the penetration of chloride ions into the steel sheet surface. As a result, corrosion of steel is effectively suppressed. Moreover, corrosion of steel is also suppressed by the inhibitor action of WO 4 2− .

Ｃｒ：０．０１ｍａｓｓ％以上０．２０ｍａｓｓ％未満
Ｃｒは、ジンクプライマーとエポキシ樹脂塗膜の存在下で、優れた耐食性を発現する成分であり、本発明の船舶用熱間圧延形鋼においては、重要な元素の１つである。上記耐食性向上効果は、ジンクプライマーが存在する場合には、ジンクプライマー中のＺｎが溶出して、ＺｎＯやＺｎＣｌ２・４Ｚｎ（ＯＨ）２等のＺｎ系腐食生成物が生成されるが、Ｃｒは、このＺｎ系腐食生成物に作用して、Ｚｎ系腐食生成物による地鉄防食性をより向上させる働きがあるものと推定される。このような、ジンクプライマー存在下でのＣｒの耐食性向上効果は、０．０１ｍａｓｓ％以上の含有で発現する。しかし、０．２０ｍａｓｓ％以上含有すると、溶接部靭性を低下させる。よって、Ｃｒ含有量は、０．０１ｍａｓｓ％以上０．２０ｍａｓｓ％未満の範囲とする。好ましくは０．０２〜０．１５ｍａｓｓ％の範囲である。なお、前述のように、上記範囲のＣｒおよびＷを共に添加すると、塗膜の種類や有無にかかわらず、極めて良好な耐食性を得ることができる。 Cr: 0.01 mass% or more and less than 0.20 mass% Cr is a component that exhibits excellent corrosion resistance in the presence of a zinc primer and an epoxy resin coating film. One of the important elements. When the zinc primer is present, the corrosion resistance improving effect is as follows. Zn in the zinc primer is eluted, and Zn-based corrosion products such as ZnO and ZnCl 2 · 4Zn (OH) 2 are generated. It is presumed that it acts on this Zn-based corrosion product and has a function of further improving the anticorrosion property of the base iron by the Zn-based corrosion product. Such an effect of improving the corrosion resistance of Cr in the presence of a zinc primer is manifested when the content is 0.01 mass% or more. However, when it contains 0.20 mass% or more, the weld zone toughness is lowered. Therefore, the Cr content is set to a range of 0.01 mass% or more and less than 0.20 mass%. Preferably it is the range of 0.02-0.15 mass%. As described above, when both Cr and W in the above range are added, extremely good corrosion resistance can be obtained regardless of the type and presence of the coating film.

Ｎ：０．００１〜０．００８ｍａｓｓ％
Ｎは、鋼の靭性に対しては有害な成分である。したがって、靭性の向上を図るためには、Ｎは、できるだけ低減することが望ましく、０．００８ｍａｓｓ％以下とする。しかし、工業的には、Ｎを０．００１ｍａｓｓ％未満に低減するのは難しい。よって、本発明では、Ｎ含有量は０．００１〜０．００８ｍａｓｓ％の範囲とする。 N: 0.001 to 0.008 mass%
N is a harmful component for the toughness of steel. Therefore, in order to improve toughness, N is desirably reduced as much as possible, and is set to 0.008 mass% or less. However, industrially, it is difficult to reduce N to less than 0.001 mass%. Therefore, in the present invention, the N content is in the range of 0.001 to 0.008 mass%.

本発明の船舶用熱間圧延形鋼は、耐食性のさらなる向上を目的として、上記成分に加えてさらに、下記の成分を添加することができる。
Ｓｂ：０．００１〜０．３ｍａｓｓ％およびＳｎ：０．００１〜０．３ｍａｓｓ％のうちの１種または２種
Ｓｂは、ジンクプライマーとエポキシ樹脂塗膜存在下、エポキシ樹脂塗膜存在下および裸状態での耐食性を向上させる効果がある。また、Ｓｎは、エポキシ樹脂塗膜存在下および裸状態のいずれにおいても耐食性を向上させる効果がある。Ｓｂ，Ｓｎの上記効果は、鋼板表面のアノード部などのｐＨが低下した部位の腐食を抑制するためと考えられる。これらの効果は、Ｓｎ，Ｓｂとも０．００１ｍａｓｓ％以上の含有により発現する。しかし、０．３ｍａｓｓ％を超えて添加すると、母材靭性およびＨＡＺ部靭性が低下するため、それぞれ０．００１〜０．３ｍａｓｓ％の範囲で添加するのが好ましい。なお、ＳｂおよびＳｎの両方を添加することがさらに好ましい。 In addition to the said component, the following component can be further added to the hot rolled shape steel for ships of this invention in order to further improve corrosion resistance.
One or two of Sb: 0.001 to 0.3 mass% and Sn: 0.001 to 0.3 mass% Sb is present in the presence of a zinc primer and an epoxy resin coating, in the presence of an epoxy resin coating and bare There is an effect of improving the corrosion resistance in the state. Sn has an effect of improving the corrosion resistance both in the presence of the epoxy resin coating film and in the bare state. The above effect of Sb and Sn is considered to suppress corrosion of a portion where the pH is lowered, such as the anode portion on the steel sheet surface. These effects are manifested when both Sn and Sb are contained in an amount of 0.001 mass% or more. However, if added over 0.3 mass%, the base material toughness and the HAZ part toughness are lowered, so it is preferable to add each in the range of 0.001 to 0.3 mass%. It is more preferable to add both Sb and Sn.

Ｃｕ：０．００５〜０．５ｍａｓｓ％、Ｎｉ：０．００５〜０．２５ｍａｓｓ％、Ｍｏ：０．０１〜０．５ｍａｓｓ％およびＣｏ：０．０１〜１．０ｍａｓｓ％のうちの１種または２種以上
Ｃｕ，Ｎｉ，ＭｏおよびＣｏは、ジンクプライマーとエポキシ塗膜の存在下および裸の状態における鋼の耐食性を向上し、さらに、Ｍｏは、エポキシ塗膜存在下でも、耐食性を向上する効果がある。したがって、これらの元素は、耐食性をより向上させたい場合に、補助的に含有させることができる。Ｃｕ，Ｎｉ，Ｍｏ，Ｃｏの上記効果は、錆粒子の微細化作用によるものと考えられ、さらに、Ｍｏの場合には、錆中にＭｏＯ４ ２−が生成することにより塩化物イオンが鋼板表面に侵入するのを抑制することも寄与していると考えられる。これらの効果は、Ｃｕ，Ｎｉでは０．００５ｍａｓｓ％以上、Ｍｏでは０．０１ｍａｓｓ％以上、Ｃｏでは０．０１ｍａｓｓ％以上含有することで発現する。しかし、Ｃｕ：０．５ｍａｓｓ％超え、Ｎｉ：０．２５ｍａｓｓ％超え、Ｍｏ：０．５ｍａｓｓ％超え、Ｃｏ：１．０ｍａｓｓ％超え添加しても、その効果は飽和し、経済的にも不利となる。よって、Ｃｕ，Ｎｉ，ＭｏおよびＣｏは、それぞれ上記範囲で添加するのが好ましい。 One or two of Cu: 0.005-0.5 mass%, Ni: 0.005-0.25 mass%, Mo: 0.01-0.5 mass% and Co: 0.01-1.0 mass% More than seeds Cu, Ni, Mo and Co improve the corrosion resistance of steel in the presence of zinc primer and epoxy coating and in the bare state, and Mo has the effect of improving the corrosion resistance even in the presence of epoxy coating. is there. Therefore, these elements can be supplementarily contained when it is desired to further improve the corrosion resistance. The above effect of Cu, Ni, Mo, Co is considered to be due to the refinement action of rust particles. Furthermore, in the case of Mo, chloride ions are formed on the surface of the steel sheet by generating MoO 4 2− during rust. It is thought that it has also contributed to suppressing intrusion into the water. These effects are manifested by containing 0.005 mass% or more in Cu, Ni, 0.01 mass% or more in Mo, and 0.01 mass% or more in Co. However, even if Cu: more than 0.5 mass%, Ni: more than 0.25 mass%, Mo: more than 0.5 mass%, Co: more than 1.0 mass%, the effect is saturated and economically disadvantageous. Become. Therefore, Cu, Ni, Mo, and Co are preferably added in the above ranges.

さらに本発明の熱間圧延形鋼は、強度を高めたり、靭性を向上させたりするため、上記成分に加えてさらに、下記の成分を含有することができる。
Ｎｂ：０．００１〜０．１ｍａｓｓ％、Ｔｉ：０．００１〜０．１ｍａｓｓ％、Ｚｒ：０．００１〜０．１ｍａｓｓ％およびＶ：０．００２〜０．２ｍａｓｓ％のうちの１種または２種以上
Ｎｂ，Ｔｉ，ＺｒおよびＶは、いずれも鋼の強度を高める元素であり、必要とする強度に応じて選択して添加することができる。このような効果を得るためには、Ｎｂ，Ｔｉ，Ｚｒは、それぞれ０．００１ｍａｓｓ％以上、Ｖは０．００２ｍａｓｓ％以上添加することが好ましい。しかし、Ｎｂ，Ｔｉ，Ｚｒは０．１ｍａｓｓ％、Ｖは０．２ｍａｓｓ％を超えて添加すると、却って靭性が低下するため、Ｎｂ，Ｔｉ，Ｚｒ，Ｖは、上記値を上限として添加するのが好ましい。好ましい上限は０．０４ｍａｓｓ％である。これらの元素の中では、溶接部靭性の観点からＴｉが最も好ましく、Ｎｂはこれに次いで好ましい。 Furthermore, in order to increase the strength and improve the toughness, the hot rolled steel of the present invention can further contain the following components in addition to the above components.
One or two of Nb: 0.001 to 0.1 mass%, Ti: 0.001 to 0.1 mass%, Zr: 0.001 to 0.1 mass%, and V: 0.002 to 0.2 mass% More than seeds Nb, Ti, Zr and V are all elements that increase the strength of steel, and can be selected and added according to the required strength. In order to obtain such an effect, it is preferable to add Nb, Ti, and Zr in an amount of 0.001 mass% or more, and V in an amount of 0.002 mass% or more. However, if Nb, Ti, Zr is added in an amount of 0.1 mass% and V exceeds 0.2 mass%, the toughness is lowered. On the other hand, Nb, Ti, Zr, V should be added up to the above value. preferable. A preferable upper limit is 0.04 mass%. Among these elements, Ti is the most preferable from the viewpoint of weld toughness, and Nb is the next most preferable.

Ｂ：０．０００２〜０．００３ｍａｓｓ％
Ｂは、鋼の強度を高める元素であり、必要に応じて含有することができる。上記効果を得るためには、０．０００２ｍａｓｓ％以上添加するのが好ましい。しかし、０．００３ｍａｓｓ％を超えて添加すると、靭性が却って低下する。よって、Ｂは０．０００２〜０．００３ｍａｓｓ％の範囲で添加するのが好ましい。 B: 0.0002 to 0.003 mass%
B is an element that increases the strength of the steel, and can be contained as necessary. In order to acquire the said effect, adding 0.0002 mass% or more is preferable. However, if added over 0.003 mass%, the toughness is reduced instead. Therefore, it is preferable to add B in the range of 0.0002 to 0.003 mass%.

Ｃａ：０．０００２〜０．０１ｍａｓｓ％，ＲＥＭ：０．０００２〜０．０１５ｍａｓｓ％およびＹ：０．０００１〜０．１ｍａｓｓ％のうちの１種または２種以上
Ｃａ，ＲＥＭおよびＹは、いずれも溶接熱影響部の靭性向上に効果のある元素であり、必要に応じて選択して添加することができる。この効果は、Ｃａ：０．０００２ｍａｓｓ％以上、ＲＥＭ：０．０００２ｍａｓｓ％以上、Ｙ：０．０００１ｍａｓｓ％以上の添加で得られる。しかし、Ｃａ：０．０１ｍａｓｓ％、ＲＥＭ：０．０１５ｍａｓｓ％、Ｙ：０．１ｍａｓｓ％を超えて添加すると、却って靭性の低下を招くので、Ｃａ，ＲＥＭ，Ｙは、それぞれ上記値を上限として添加するのが好ましい。 Ca: 0.0002 to 0.01 mass%, REM: 0.0002 to 0.015 mass%, and Y: 0.0001 to 0.1 mass%, or two or more of Ca, REM, and Y It is an element effective in improving the toughness of the weld heat affected zone, and can be selected and added as necessary. This effect can be obtained by adding Ca: 0.0002 mass% or more, REM: 0.0002 mass% or more, and Y: 0.0001 mass% or more. However, since Ca: 0.01 mass%, REM: 0.015 mass%, and Y: addition exceeding 0.1 mass% will cause a decrease in toughness, Ca, REM and Y are added with the above values as the upper limit. It is preferable to do this.

本発明の船舶用熱間圧延形鋼においては、上記以外の成分は、Ｆｅおよび不可避的不純物である。ただし、本発明の効果を害しない範囲内であれば、上記以外の成分の含有を拒むものではない。   In the hot-rolled steel section for ships of the present invention, components other than the above are Fe and inevitable impurities. However, as long as the effects of the present invention are not impaired, the inclusion of components other than those described above is not rejected.

次に、本発明に係る高強度でかつ耐食性に優れる船舶用熱間圧延形鋼のミクロ組織について説明する。
船舶用鋼板、とりわけ、降伏応力ＹＰが３１５ＭＰａ以上の高強度厚鋼板においては、一般に、低炭素当量として高い溶接性を付与した鋼素材を、制御圧延と制御冷却を組み合わせたＴＭＣＰを採用し、第２相として硬質のベイナイト組織を導入することで高強度化を達成している。そして、低温靭性が求められる場合や、厚肉化への要求に対しては、上記制御圧延および制御冷却の条件を最適化することで対応している。したがって、この場合、鋼板のミクロ組織は、通常、フェライト＋ベイナイト組織である。 Next, the microstructure of the marine hot-rolled section steel having high strength and excellent corrosion resistance according to the present invention will be described.
In marine steel plates, especially high strength thick steel plates with a yield stress YP of 315 MPa or more, generally, a steel material imparted with a high weldability as a low carbon equivalent is employed with TMCP combining controlled rolling and controlled cooling. High strength is achieved by introducing a hard bainite structure as two phases. And the case where low temperature toughness is calculated | required and the request | requirement to thickening respond | correspond by optimizing the conditions of the said controlled rolling and controlled cooling. Therefore, in this case, the microstructure of the steel sheet is usually a ferrite + bainite structure.

一方、船舶用熱間圧延形鋼の場合は、短辺と長辺の幅や厚さが異なる場合が多く（例えば、断面が矩形ではない不等辺不等厚山形鋼など）、必然的に圧延時や冷却時に温度の不均一が発生する。特に、制御冷却（加速冷却）を適用した強度調整は、残留応力が不均一となり、ねじれや曲がり、反りを誘発し、寸法精度の低下を招くため、圧延後の形状矯正負荷が増大する。そのため、第２相として硬質のベイナイト組織を導入して高強度化するこの方法を熱間圧延形鋼に適用することは困難である。このことは、圧延Ｔ形鋼など船舶用熱間圧延形鋼全般に言えることである。   On the other hand, in the case of marine hot-rolled section steel, the width and thickness of the short side and the long side are often different (for example, unequal side unequal thick angle steel with a non-rectangular cross section), and inevitably rolled. Temperature unevenness occurs during cooling and cooling. In particular, strength adjustment using controlled cooling (accelerated cooling) results in uneven residual stress, inducing twisting, bending, warping, and a reduction in dimensional accuracy, thus increasing the shape correction load after rolling. Therefore, it is difficult to apply this method of increasing the strength by introducing a hard bainite structure as the second phase to the hot rolled shape steel. This is true for all of the marine hot-rolled sections such as rolled T-sections.

したがって、船舶用熱間圧延形鋼においては、圧延後の加速冷却を行うことなく、降伏応力ＹＰ：３１５ＭＰａ以上かつ引張強さＴＳ：４４０ＭＰａ以上の高強度を達成することが求められる。このためには、通常の熱間圧延組織であるフェライト＋パーライト組織で高強度化を図る必要がある。フェライト＋パーライト組織で高強度化を実現する手段としては、第２相のパーライト分率を増やす方法、フェライト組織を一層細粒化する方法、フェライトを固溶強化や析出強化して硬くする方法、あるいは（γ＋α）２相域で熱間圧延して、フェライトの一部を高転位密度の加工フェライトとする方法等が考えられる。   Accordingly, in the marine hot-rolled section steel, it is required to achieve a high strength of yield stress YP: 315 MPa or more and tensile strength TS: 440 MPa or more without performing accelerated cooling after rolling. For this purpose, it is necessary to increase the strength with a ferrite + pearlite structure which is a normal hot rolled structure. As a means to achieve high strength in the ferrite + pearlite structure, a method of increasing the pearlite fraction of the second phase, a method of further reducing the ferrite structure, a method of hardening the ferrite by solid solution strengthening or precipitation strengthening, Alternatively, a method of hot rolling in the (γ + α) two-phase region to make a part of the ferrite a processed ferrite having a high dislocation density can be considered.

上記方法のうち、フェライトを細粒化する方法は、ＹＰを上昇させるには有利であるが、ＴＳの上昇は小さいため、この手法のみでは十分な高強度化は図れない。また、パーライト分率を増加する方法は、Ｃを多量に添加する必要があるが、Ｃの過度な添加は溶接性の低下を招くため好ましくない。また、固溶強化元素や析出強化元素を添加してフェライトを強化する方法は、合金元素の多量添加により溶接性の低下を招いたり、素材コストの上昇を招いたりする。一方、加工フェライトの活用は、Ｃや合金元素の添加を最小限に抑制し、溶接性を維持した状態で、ＹＰおよびＴＳを上昇させることができる。すなわち、加工フェライトを利用する方法は、熱間圧延後、制御冷却（加速冷却）することなく高強度化を図ることができるので、船舶用熱間圧延形鋼製造時の固有の問題である圧延、冷却時の曲がりや反りの発生を抑えながら、高強度化することが可能である。そこで、本発明においては、船舶用熱間圧延形鋼の高強度化手段として、鋼のミクロ組織を、加工フェライトを含むフェライト＋パーライト組織とする方法を採用することとした。   Of the above methods, the method of refining ferrite is advantageous for increasing YP, but since the increase in TS is small, sufficient strength cannot be achieved by this method alone. Moreover, although the method of increasing a pearlite fraction needs to add C in large quantities, since excessive addition of C causes the fall of weldability, it is unpreferable. Moreover, the method of strengthening ferrite by adding a solid solution strengthening element or a precipitation strengthening element causes a decrease in weldability or an increase in material cost due to the addition of a large amount of alloy elements. On the other hand, the utilization of processed ferrite can suppress the addition of C and alloy elements to the minimum, and can increase YP and TS while maintaining weldability. In other words, since the method using the processed ferrite can achieve high strength without hot-rolling and controlled cooling (accelerated cooling), rolling is a problem inherent in the production of hot-rolled section steel for ships. It is possible to increase the strength while suppressing the occurrence of bending and warping during cooling. Therefore, in the present invention, as a means for increasing the strength of the marine hot-rolled section steel, a method is adopted in which the microstructure of the steel is a ferrite containing processed ferrite + pearlite structure.

ここで、上記加工フェライトの分率は、面積率にして鋼組織全体の１０〜７０％の範囲であることが好ましい。加工フェライトの分率が１０％未満では、鋼の強化が十分に得られず、一方、７０％超えでは、強度上昇が飽和すると共に、（α＋γ）の２相域圧延時の荷重増大に伴うロール割損リスクが増加するからである。なお、上記加工フェライトは、Ａｒ３変態点以下の（α＋γ）２相域での熱間圧延によって形成された加工歪が導入されたフェライトのことであり、通常、扁平化した加工フェライトをトレースし、ミクロ組織中に占める面積を定量化し、その分率を測定することができる。ミクロ組織の測定位置としては、最も板厚の厚い部位における板厚１／４部が好ましい。
なお、加工フェライトを含むフェライト全体では、面積率で鋼組織全体の１０〜７０％程度存在することが好ましい。残部は、パーライト組織であるが、フェライト・パーライト以外の組織、即ち、ベイナイト等が面積率で１０％以下存在してもよい。 Here, the fraction of the processed ferrite is preferably in the range of 10 to 70% of the entire steel structure as an area ratio. If the fraction of the processed ferrite is less than 10%, the steel cannot be sufficiently strengthened. On the other hand, if it exceeds 70%, the increase in strength is saturated and a roll accompanying an increase in load during two-phase rolling of (α + γ). This is because the risk of breakage increases. The processed ferrite is a ferrite into which a working strain formed by hot rolling in the (α + γ) two-phase region below the Ar 3 transformation point is introduced. Usually, the flattened processed ferrite is traced. The area occupied in the microstructure can be quantified and the fraction can be measured. The measurement position of the microstructure is preferably a ¼ part thickness at the thickest part.
In addition, it is preferable that the entire ferrite including the processed ferrite is present in an area ratio of about 10 to 70% of the entire steel structure. The balance is a pearlite structure, but a structure other than ferrite and pearlite, that is, bainite or the like may be present in an area ratio of 10% or less.

次に、上記加工フェライトを含むフェライト＋パーライト組織を有する船舶用熱間圧延形鋼を製造する方法について説明する。
本発明の船舶用熱間圧延形鋼の製造に当たっては、先ず、上記した成分組成を有する鋼を転炉、電気炉等通常公知の方法で溶製し、連続鋳造法、造塊法等通常公知の方法でスラブやビレット等の鋼素材とするのが好ましい。なお、溶製後、取鍋精錬や真空脱ガス等の処理を付加しても良い。 Next, a method for producing a marine hot-rolled section steel having a ferrite + pearlite structure containing the processed ferrite will be described.
In producing the marine hot-rolled section steel of the present invention, first, steel having the above-described component composition is melted by a generally known method such as a converter, an electric furnace, etc., and a generally known method such as a continuous casting method or an ingot forming method. It is preferable to use a steel material such as a slab or billet by the above method. In addition, after melting, treatment such as ladle refining or vacuum degassing may be added.

次いで、上記鋼素材を、加熱炉に装入して再加熱後、熱間圧延して所望の寸法、組織及び特性を有する船舶用熱間圧延形鋼とする。この際、鋼素材の再加熱温度は１０００〜１３５０℃の範囲とする必要がある。加熱温度が１０００℃未満では変形抵抗が大きく、熱間圧延が難しくなる。一方、１３５０℃を超える加熱は、表面痕の発生原因となったり、スケールロスや燃料原単位が増加したりする。好ましくは、１１００〜１３００℃の範囲である。   Next, the steel material is charged into a heating furnace, reheated, and hot-rolled to obtain a hot-rolled steel for ships having desired dimensions, structure, and characteristics. At this time, the reheating temperature of the steel material needs to be in the range of 1000 to 1350 ° C. When the heating temperature is less than 1000 ° C., the deformation resistance is large and hot rolling becomes difficult. On the other hand, heating exceeding 1350 ° C. causes generation of surface marks, or increases scale loss and fuel consumption rate. Preferably, it is the range of 1100-1300 degreeC.

続く熱間圧延は、Ａｒ３温度以下での累積圧下率を１０〜８０％とする必要がある。圧延温度がＡｒ３温度以上では、鋼のミクロ組織が加工フェライトを含まないものとなり、必要な強度、靭性を確保することができない。同様に、Ａｒ３温度以下での累積圧下率が１０％未満では、加工フェライトの生成量が少ないため、強靭化効果が小さい。逆に、８０％を超える圧下率になると、圧延荷重が増大して圧延が困難となったり、圧延のパス回数が増えて生産性の低下を招いたりする。よって、Ａｒ３温度以下での累積圧下率は１０〜８０％とする。好ましくは、１０〜６０％の範囲である。なお、Ａｒ３温度以下での圧延は、少なくとも１パス以上行えばよく、複数パスとなっても構わない。ここで、Ａｒ３温度以下での累積圧下率とは、Ａｒ３温度における圧延材の断面積（Ａ）に対する圧延終了後の圧延材の断面積（Ｂ）の断面減面率のことを指し、以下の式で表される。
（Ａｒ３温度以下での累積圧下率〔％〕）＝１００×（Ａ−Ｂ）／Ａ In the subsequent hot rolling, it is necessary that the cumulative rolling reduction at the Ar 3 temperature or lower is 10 to 80%. When the rolling temperature is Ar 3 temperature or higher, the microstructure of the steel does not contain processed ferrite, and the required strength and toughness cannot be ensured. Similarly, if the cumulative rolling reduction at an Ar 3 temperature or less is less than 10%, the toughening effect is small because the amount of processed ferrite produced is small. Conversely, when the rolling reduction exceeds 80%, the rolling load increases and rolling becomes difficult, or the number of rolling passes increases, leading to a decrease in productivity. Therefore, the cumulative rolling reduction at the Ar 3 temperature or lower is set to 10 to 80%. Preferably, it is 10 to 60% of range. Note that rolling at an Ar 3 temperature or lower may be performed at least one pass, or may be a plurality of passes. Here, the cumulative rolling reduction at Ar 3 temperature or less, refers to a cross-section area reduction rate of the cross-sectional area of the rolled material after rolling completion to the cross-sectional area of the rolled material (A) in the Ar 3 temperature (B), It is expressed by the following formula.
(Cumulative rolling reduction [%] at Ar 3 temperature or lower [%]) = 100 × (A−B) / A

また、上記熱間圧延は、圧延仕上温度を（Ａｒ３−３０℃）〜（Ａｒ３−１８０℃）の条件で行う必要がある。圧延仕上温度が、（Ａｒ３−３０℃）超えでは、２相域圧延による強靭化効果が十分に得られず、一方、（Ａｒ３−１８０℃）未満では、変形抵抗の増大により圧延荷重が増加し、圧延することが困難となるからである。 Further, between the hot rolling needs to be performed in the conditions of the finish rolling temperature (Ar 3 -30 ℃) ~ ( Ar 3 -180 ℃). When the rolling finishing temperature exceeds (Ar 3 -30 ° C), the toughening effect by the two-phase region rolling cannot be sufficiently obtained. On the other hand, when the rolling finishing temperature is less than (Ar 3 -180 ° C), the rolling load increases due to the increase in deformation resistance. It is because it increases and it becomes difficult to roll.

さらに、上記熱間圧延においては、Ａｒ３温度以下での圧延を、船舶用熱間圧延形鋼の断面内の各部位における温度差を５０℃以内として行うことが好ましい。例えば、船舶用熱間圧延形鋼の中で、長辺と短辺とで肉厚に差のある不等辺不等厚山形鋼については、肉厚の薄い長辺側よりも肉厚の厚い短辺側を圧延機の前後で水冷して、長辺側と短辺側の温度差を５０℃以内に抑えることが好ましい。温度差が５０℃を超えると、短辺側と長辺側の強度、靭性特性のばらつきが大きくなるばかりでなく、圧延後の冷却工程での曲がりが大きくなり、矯正に要する負担が大きくなって生産性を低下させる。なお、形鋼の断面内の温度差は、フランジとウェブの表面温度を放射温度計で測定し、得られた最高温度と最低温度との差により求める。 Further, in the above hot rolling, it is preferable to perform rolling at an Ar 3 temperature or less so that the temperature difference at each part in the cross section of the marine hot rolled section steel is within 50 ° C. For example, among the hot-rolled steel shapes for ships, for unequal side unequal thick angle steels with a difference in wall thickness between the long side and the short side, the short side is thicker than the long side where the wall is thin. It is preferable that the side is cooled with water before and after the rolling mill to suppress the temperature difference between the long side and the short side to within 50 ° C. If the temperature difference exceeds 50 ° C., not only the variation in strength and toughness characteristics between the short side and the long side will increase, but also the bending in the cooling process after rolling will increase, and the burden required for correction will increase. Reduce productivity. The temperature difference in the cross section of the section steel is obtained by measuring the surface temperature of the flange and the web with a radiation thermometer and obtaining the difference between the maximum temperature and the minimum temperature obtained.

短辺側と長辺側の温度差を５０℃以内に抑える手段としては、粗圧延機の前後に配置された冷却設備を用いて冷却を制御する方法が好ましい。具体的には、上記冷却設備により、肉厚の厚い短辺側を重点的に水冷し温度差を解消する方法が好ましい。この際の水冷は、圧延機前後の前面のみ、後面のみあるいは、前後の両方で行ってもよく、また、圧延する形鋼の寸法や要求精度に応じて、複数回の亘って行っても構わない。なお、水冷の際の水量密度は、１ｍ３／ｍ・ｍｉｎ以上であることが好ましい。 As a means for suppressing the temperature difference between the short side and the long side to be within 50 ° C., a method of controlling cooling using cooling equipment disposed before and after the rough rolling mill is preferable. Specifically, a method of eliminating the temperature difference by intensively water-cooling the thicker short side with the cooling facility is preferable. The water cooling at this time may be performed only on the front surface before and after the rolling mill, only on the rear surface, or both on the front and back sides, or may be performed a plurality of times depending on the dimensions and required accuracy of the shape steel to be rolled. Absent. The water density at the time of water cooling is preferably 1 m 3 / m · min or more.

熱間圧延に続く冷却は、特に制限はないが、放冷することが好ましい。これにより、圧延後の冷却不均一から生じる曲がりや反りといった形鋼の形状変化を軽減することができ、圧延後の製品に対する矯正の負担を軽減することができる。   The cooling following the hot rolling is not particularly limited, but it is preferable to cool. Thereby, the shape change of the shape steel, such as bending and warping resulting from non-uniform cooling after rolling, can be reduced, and the correction burden on the product after rolling can be reduced.

表２に示した成分組成を有する鋼を真空溶解炉または転炉で溶製してブルームとし、このブルームを加熱炉に装入して加熱後、表３に示した条件で熱間圧延し、表３に示した断面寸法の不等辺不等厚山形鋼（ＮＡＢ）および圧延Ｔ形鋼を製造した。なお、表３において、不等辺不等厚山形鋼（ＮＡＢ）については、長辺側をウェブ、短辺側をフランジとして示している。不等辺不等厚山形鋼については短辺から、Ｔ形鋼についてはフランジから、ＪＩＳ１Ａ号引張試験片を採取し、引張特性（降伏応力ＹＰ，引張強さＴＳ，伸びＥｌ）を測定した。また、不等辺不等厚山形鋼については短辺を、Ｔ形鋼についてはフランジを、２０ｋＪ／ｃｍの入熱で突合せ多層盛り溶接（ＧＭＡＷ）したＨＡＺ中央部から、シャルピー衝撃試験片（２ｍｍＶノッチ試験片）を採取し、−２０℃でのシャルピー衝撃試験における吸収エネルギーを測定した。また、不等辺不等厚山形鋼については短辺から、Ｔ形鋼についてはフランジから、組織観察用の試料を採取し、板厚１／４部の組織を顕微鏡で倍率２００倍で観察し、２相域圧延で生成した扁平化した加工フェライトをトレースし、ミクロ組織中に占める面積を画像解析により定量化し、加工フェライトの分率を求めた。   Steel having the composition shown in Table 2 was melted in a vacuum melting furnace or converter to form a bloom, and after this bloom was charged in a heating furnace and heated, it was hot-rolled under the conditions shown in Table 3. Unequal-sided unequal thick angle steel (NAB) and rolled T-shaped steel having the cross-sectional dimensions shown in Table 3 were produced. In Table 3, regarding the unequal side unequal thick angle steel (NAB), the long side is shown as a web and the short side is shown as a flange. JIS1A tensile test specimens were collected from the short side for unequal side unequal thick angle steel and from the flange for T-shaped steel, and the tensile properties (yield stress YP, tensile strength TS, elongation El) were measured. Also, Charpy impact test piece (2mmV notch) from the center of HAZ where butt multi-layer welding (GMAW) was applied with heat input of 20kJ / cm, short side for unequal side unequal thickness angle steel and T-type flange. Test piece) was collected, and the absorbed energy in a Charpy impact test at -20 ° C was measured. In addition, a sample for observing the structure was collected from the short side for the unequal side unequal thickness angle steel, and from the flange for the T shape steel, and the structure having a thickness of 1/4 part was observed with a microscope at a magnification of 200 times. The flattened processed ferrite produced by two-phase rolling was traced, and the area occupied in the microstructure was quantified by image analysis to determine the fraction of processed ferrite.

Figure 0005396758
Figure 0005396758

Figure 0005396758
Figure 0005396758

次に、それぞれの熱間圧延形鋼について、不等辺不等厚山形鋼については短辺から、Ｔ形鋼についてはフランジから、５ｍｍｔ×１００ｍｍＷ×２００ｍｍＬまたは５ｍｍｔ×５０ｍｍＷ×１５０ｍｍＬの試験片を採取し、試験片表面をショットブラスト後、以下の条件Ａ〜Ｃの表面処理を施して耐食性試験片とした。
＜表面処理条件＞
条件Ａ：試験片表面に、ジンクプライマー（膜厚約１５μｍ）とタールエポキシ樹脂塗料（膜厚約２００μｍ）の２層被膜を形成
条件Ｂ：試験片表面に、タールエポキシ樹脂塗料（膜厚約２００μｍ）の単層被膜を形成
条件Ｃ：試験片表面に、ショットブラストしたままの裸状態（防食被膜なし）
なお、塗膜を形成した上記条件ＡおよびＢの試験片には、塗膜の上からカッターナイフで地鉄表面まで達する長さ８０ｍｍのスクラッチ疵を一文字状に付与した。 Next, for each hot-rolled section steel, a test piece of 5 mmt × 100 mmW × 200 mmL or 5 mmt × 50 mmW × 150 mmL was taken from the short side of the unequal side unequal thickness angle steel and from the flange of the T shape steel. The surface of the test piece was shot blasted and then subjected to surface treatment under the following conditions A to C to obtain a corrosion resistance test piece.
<Surface treatment conditions>
Condition A: Two-layer coating of zinc primer (film thickness of about 15 μm) and tar epoxy resin paint (film thickness of about 200 μm) is formed on the surface of the test piece Condition B: Tar epoxy resin paint (film thickness of about 200 μm) on the surface of the test piece ) Condition C: Bare state with shot blasting on test piece surface (no anticorrosion coating)
In addition, the test piece of the said conditions A and B which formed the coating film was provided with the scratch scissors of 80 mm in length which reaches the surface of the iron bar with a cutter knife from the top of the coating film.

上記のようにして作製した試験片は、その後、実船のバラストタンク上甲板の裏側に２年間装着する暴露試験に供した。この暴露試験の腐食環境は、平均して、バラストタンク内に海水が入っている期間が約２０日、海水が入っていない期間が約２０日を１サイクルとし、これを繰り返すものであった。暴露試験における耐食性の評価は、塗膜を有する条件ＡおよびＢの試験片については、スクラッチ疵の周囲に発生した塗膜膨れ面積を測定し、また、塗膜を有しない条件Ｃの試験片については、試験後、脱錆し、その脱錆した後の試験片質量と試験前の試験片質量の差（減少量）から平均板厚減少量を算出し、これらの結果を、耐食性向上元素を特に含まないＮｏ．１２の鋼をベース（１００）として、それに対する各試験片の比を算出し、評価した。   The test piece produced as described above was then subjected to an exposure test that was mounted on the back side of the upper deck of the ballast tank of the actual ship for 2 years. On average, the corrosive environment of this exposure test was a cycle in which the period in which the seawater was in the ballast tank was about 20 days and the period in which the seawater was not contained was about 20 days. Corrosion resistance evaluation in the exposure test is as follows. For test pieces of conditions A and B having a coating film, the swollen area of the coating film generated around the scratch ridge is measured, and for a test piece of condition C having no coating film. After the test, derust, calculate the average reduction in thickness from the difference (decrease) in the test piece mass after the derusting and the test piece mass before the test, and use these results as the corrosion resistance improving element. No. Using 12 steels as the base (100), the ratio of each test piece was calculated and evaluated.

表４に上記引張試験、衝撃試験、ミクロ組織調査および耐食性試験の結果を示した。腐食試験の結果から、本発明の成分組成を満たす発明例のＮｏ．１〜１３（ただし、Ｎｏ．４，９は参考例）の鋼は、条件Ａ〜Ｃのいずれでも、ベース鋼（Ｎｏ．１４）に対する塗膜膨れ面積および板厚減少量が５０％以下であり、良好な耐食性を有していることがわかる。これに対して、本発明の成分組成を満たさないＮｏ．１４〜１７の鋼は、ベース鋼（Ｎｏ．１４）より耐食性が向上していても、ベース鋼に対する比率が５０％超えの条件があったり、溶接部の靭性が大きく低下していたりする。また、ミクロ組織が、加工フェライトを含むフェライト＋パーライト組織では、本発明で所期した十分な強度が得られており、曲がりや反りなどの形状変化も軽微で、生産性も極めて良好であった。
なお、圧延符号ａの形鋼（Ａｒ３以下の温度での熱間圧延において、形鋼断面内の温度差が５０℃を超えた場合）では、特性値は目標に達したものの、曲がり、反りが大きかった。 Table 4 shows the results of the tensile test, impact test, microstructure investigation, and corrosion resistance test. From the results of the corrosion test, No. of the invention example satisfying the component composition of the present invention. Steels Nos. 1 to 13 (Nos. 4 and 9 are reference examples) have a bulge area and a reduction in sheet thickness of 50% or less with respect to the base steel (No. 14) in any of the conditions AC It can be seen that it has good corrosion resistance. On the other hand, No. which does not satisfy the component composition of the present invention. Even though the steels of Nos. 14 to 17 have higher corrosion resistance than the base steel (No. 14), there are conditions where the ratio to the base steel exceeds 50%, and the toughness of the welded portion is greatly reduced. In addition, when the microstructure was a ferrite including a processed ferrite + pearlite structure, the sufficient strength as expected in the present invention was obtained, the shape change such as bending and warping was slight, and the productivity was extremely good. .
In addition, in the shape steel of the rolling code a (when the temperature difference in the cross section of the shape steel exceeds 50 ° C. in the hot rolling at a temperature of Ar 3 or lower), the characteristic value has reached the target, but it is bent and warped. Was big.

Figure 0005396758
Figure 0005396758

本発明の船舶用熱間圧延形鋼は、海水による腐食環境下で優れた耐食性を示すので、船舶の補修期間の延長を通じて船舶自体の寿命延長にも有効であるが、類似の腐食環境で使用される他の分野で用いられる熱間圧延形鋼にも用いることができる。   Since the hot-rolled steel for ships of the present invention exhibits excellent corrosion resistance in a corrosive environment caused by seawater, it is effective for extending the life of the ship itself by extending the repair period of the ship. It can also be used for hot rolled section steel used in other fields.

Claims (11)

Ｃ：０．０３〜０．２５ｍａｓｓ％、Ｓｉ：０．０５〜０．５０ｍａｓｓ％、Ｍｎ：０．１〜２．０ｍａｓｓ％、Ｐ：０．０２５ｍａｓｓ％以下、Ｓ：０．０１ｍａｓｓ％以下、Ａｌ：０．００５〜０．１０ｍａｓｓ％、Ｗ：０．０１〜１．０ｍａｓｓ％、Ｃｒ：０．０１ｍａｓｓ％以上０．２０ｍａｓｓ％未満、Ｎ：０．００１〜０．００８ｍａｓｓ％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し、加工フェライトを含むフェライトとパーライト組織とからなるミクロ組織を有する耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 C: 0.03-0.25 mass%, Si: 0.05-0.50 mass%, Mn: 0.1-2.0 mass%, P: 0.025 mass% or less, S: 0.01 mass% or less, Al : 0.005 to 0.10 mass%, W: 0.01 to 1.0 mass%, Cr: 0.01 mass% or more and less than 0.20 mass%, N: 0.001 to 0.008 mass%, the balance being A hot-rolled shape steel for ship ballast tanks having a component composition composed of Fe and inevitable impurities and having a microstructure composed of ferrite containing processed ferrite and a pearlite structure and excellent in corrosion resistance. 上記成分組成に加えてさらに、Ｓｂ：０．００１〜０．３ｍａｓｓ％およびＳｎ：０．００１〜０．３ｍａｓｓ％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に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 2. In addition to the said component composition, 1 type or 2 types chosen from Sb: 0.001-0.3mass% and Sn: 0.001-0.3mass% are contained, It is characterized by the above-mentioned. Hot-rolled section steel for ship ballast tanks with excellent corrosion resistance. 上記成分組成に加えてさらに、Ｍｏ：０．０１〜０．５ｍａｓｓ％およびＣｏ：０．０１〜１．０ｍａｓｓ％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または２に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 In addition to the above component composition, the composition further comprises one or two selected from Mo: 0.01 to 0.5 mass% and Co: 0.01 to 1.0 mass%. The hot-rolled section steel for ballast tanks of a ship excellent in corrosion resistance according to 1 or 2. 上記成分組成に加えてさらに、Ｎｂ：０．００１〜０．１ｍａｓｓ％、Ｔｉ：０．００１〜０．１ｍａｓｓ％、Ｚｒ：０．００１〜０．１ｍａｓｓ％およびＶ：０．００２〜０．２ｍａｓｓ％のうちから選ばれる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１〜３のいずれか１項に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 In addition to the above component composition, Nb: 0.001 to 0.1 mass%, Ti: 0.001 to 0.1 mass%, Zr: 0.001 to 0.1 mass%, and V: 0.002 to 0.2 mass The hot-rolled section steel for ballast tanks of a ship excellent in corrosion resistance according to any one of claims 1 to 3, comprising one or more selected from the group%. 上記成分組成に加えてさらに、Ｂ：０．０００２〜０．００３ｍａｓｓ％を含有することを特徴とする請求項１〜４のいずれか１項に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 In addition to the said component composition, B: 0.0002-0.003 mass% is contained, Hot rolling for the ballast tank of the ship excellent in corrosion resistance of any one of Claims 1-4 characterized by the above-mentioned. Shape steel. 上記成分組成に加えてさらに、Ｃａ：０．０００２〜０．０１ｍａｓｓ％、ＲＥＭ：０．０００２〜０．０１５ｍａｓｓ％およびＹ：０．０００１〜０．１ｍａｓｓ％のうちから選ばれる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１〜５のいずれか１項に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 In addition to the above component composition, one or two selected from Ca: 0.0002 to 0.01 mass%, REM: 0.0002 to 0.015 mass%, and Y: 0.0001 to 0.1 mass% The hot-rolled section steel for a ballast tank of a ship excellent in corrosion resistance according to any one of claims 1 to 5, comprising the above. 形鋼の表面に、エポキシ樹脂塗膜を有することを特徴とする請求項１〜６のいずれか１項に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 The hot-rolled shape steel for ballast tanks of ships having excellent corrosion resistance according to any one of claims 1 to 6, wherein the shape steel has an epoxy resin coating on the surface thereof. 形鋼の表面に、ジンクプライマー塗膜を有することを特徴とする請求項１〜６のいずれか１項に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 The hot rolled steel for ballast tanks for ships having excellent corrosion resistance according to any one of claims 1 to 6, wherein the steel has a zinc primer coating on the surface of the steel. 形鋼の表面に、ジンクプライマー塗膜とエポキシ樹脂塗膜とを有することを特徴とする請求項１〜６のいずれか１項に記載の耐食性に優れる船舶のバラストタンク用熱間圧延形鋼。 The hot-rolled section steel for ballast tanks of ships excellent in corrosion resistance according to any one of claims 1 to 6, wherein the surface of the section steel has a zinc primer coating and an epoxy resin coating. 請求項１〜６に記載の船舶のバラストタンク用熱間圧延形鋼を製造するに当たり、鋼素材を１０００〜１３５０℃に加熱後、Ａｒ３温度以下での累積圧下率を１０〜８０％、圧延仕上温度を（Ａｒ３−３０℃）〜（Ａｒ３−１８０℃）とする熱間圧延を施し、その後、放冷することを特徴とする船舶のバラストタンク用熱間圧延形鋼の製造方法。 In manufacturing the hot-rolled shape steel for a ballast tank of a ship according to claim 1 to 6, after rolling the steel material to 1000 to 1350 ° C., the cumulative rolling reduction at an Ar 3 temperature or lower is 10 to 80%, and rolling A method for producing a hot-rolled section steel for a ballast tank of a ship , characterized by performing hot rolling with a finishing temperature of (Ar 3 -30 ° C) to (Ar 3 -180 ° C) and then allowing to cool. 上記製造方法は、Ａｒ３温度以下での熱間圧延を、形鋼断面内の温度差を５０℃以内として行うことを特徴とする請求項１０に記載の船舶のバラストタンク用熱間圧延形鋼の製造方法。 The hot rolling steel for ballast tanks of a ship according to claim 10, wherein the manufacturing method performs hot rolling at an Ar 3 temperature or less with a temperature difference within a section of the steel shape within 50 ° C. Manufacturing method.
JP2008178598A 2007-07-27 2008-07-09 Hot-rolled section steel for ship ballast tank and manufacturing method thereof Active JP5396758B2 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
JP2008178598A JP5396758B2 (en) 2007-07-27 2008-07-09 Hot-rolled section steel for ship ballast tank and manufacturing method thereof
KR1020127033613A KR20130004605A (en) 2007-07-27 2008-07-24 Hot-rolled shape steel for ships and process for manufacturing the same
KR1020107001564A KR101241935B1 (en) 2007-07-27 2008-07-24 Hot-rolled shape steel for ships and process for manufacturing the same
PCT/JP2008/063710 WO2009017177A1 (en) 2007-07-27 2008-07-24 Hot-rolled shape steel for ships and process for manufacturing the same
CN2008801004873A CN101772583B (en) 2007-07-27 2008-07-24 Hot-rolled shape steel for ships and process for manufacturing the same
TW097128385A TWI391499B (en) 2007-07-27 2008-07-25 Hot-rolled shape steel for ships and process for manufacturing the same

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2007196261 2007-07-27
JP2007196261 2007-07-27
JP2008178598A JP5396758B2 (en) 2007-07-27 2008-07-09 Hot-rolled section steel for ship ballast tank and manufacturing method thereof

Publications (2)

Publication Number Publication Date
JP2009052136A JP2009052136A (en) 2009-03-12
JP5396758B2 true JP5396758B2 (en) 2014-01-22

Family

ID=40503458

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2008178598A Active JP5396758B2 (en) 2007-07-27 2008-07-09 Hot-rolled section steel for ship ballast tank and manufacturing method thereof

Country Status (4)

Country Link
JP (1) JP5396758B2 (en)
KR (2) KR20130004605A (en)
CN (1) CN101772583B (en)
TW (1) TWI391499B (en)

Families Citing this family (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5375246B2 (en) * 2009-03-25 2013-12-25 Ｊｆｅスチール株式会社 Corrosion-resistant steel for crude oil tank and its manufacturing method
JP5515353B2 (en) * 2009-03-25 2014-06-11 Ｊｆｅスチール株式会社 Hot rolled T-section steel and manufacturing method thereof
JP2010229526A (en) * 2009-03-30 2010-10-14 Jfe Steel Corp Highly-corrosion-resistant painted steel material
JP5617191B2 (en) * 2009-06-15 2014-11-05 Ｊｆｅスチール株式会社 Marine steel with excellent film swell resistance
JP5481980B2 (en) * 2009-07-16 2014-04-23 Ｊｆｅスチール株式会社 Marine steel with excellent film swell resistance
JP2011231365A (en) * 2010-04-27 2011-11-17 Jfe Steel Corp Hot rolled shape steel for vessel and method of manufacturing the same
KR101242807B1 (en) * 2010-09-29 2013-03-12 주식회사 포스코 Low alloy hot-rolled steel sheet having excellent corrosion resistance and method for manufacturing the same
KR101243011B1 (en) * 2010-09-29 2013-03-12 주식회사 포스코 High strength low alloy hot-rolled steel sheet having excellent corrosion resistance and method for manufacturing the same
CN103014484A (en) * 2011-09-26 2013-04-03 株式会社神户制钢所 Steel plate with little welding strain
WO2013099177A1 (en) * 2011-12-27 2013-07-04 Ｊｆｅスチール株式会社 High-strength thick steel plate for construction having excellent characteristics for preventing diffusion of brittle cracks, and production method therefor
JP2013227610A (en) * 2012-04-25 2013-11-07 Jfe Steel Corp Corrosion resistant steel for hold of coal carrier or coal/ore carrier
JP5979063B2 (en) * 2012-05-23 2016-08-24 Ｊｆｅスチール株式会社 Method for producing marine steel with excellent corrosion resistance and base metal toughness
KR101461740B1 (en) * 2012-12-21 2014-11-14 주식회사 포스코 Hot rolled steel sheet having low deviation of mechanical property and thickness and excellent coating detachment resistance and method for manufacturing the same
CN104404395B (en) * 2014-11-11 2016-09-28 南京钢铁股份有限公司 Oil carrier oil cargo tank anti-corrosion flat-bulb steel and smelting process thereof
CN105349883A (en) * 2015-12-07 2016-02-24 张家港市新凯带钢制造有限公司 Corrosion-resistant alloy steel
CN105886905A (en) * 2016-06-21 2016-08-24 泉州市惠安闽投商贸有限公司 Alloy material for compressed air system of marine drilling platform and preparation method of alloy material
CN105970086B (en) * 2016-06-29 2018-04-20 巢湖鹏远金属焊管有限公司 High-strength corrosion-resisting straight welded pipe steel
KR101879082B1 (en) * 2016-12-21 2018-07-16 주식회사 포스코 Ultra high strength steel having low yield ratio method for manufacturing the same
JP6624130B2 (en) * 2017-03-14 2019-12-25 Ｊｆｅスチール株式会社 Steel material and method of manufacturing the same
CN106929741A (en) * 2017-05-10 2017-07-07 高金建 A kind of steel alloy for forging high-pressure solenoid valve valve rod
CN106929761A (en) * 2017-05-11 2017-07-07 高金建 A kind of new type stainless steel. corrosion resistance for manufacturing phone housing
CN110076196B (en) * 2019-05-15 2020-05-22 南京钢铁股份有限公司 Production method of crack arrest steel for container ship
CN112621125B (en) * 2020-12-14 2021-08-24 桃江富硕精密机械有限公司 High-lubrication wear-resistant mechanical arm guide rail
CN113528956A (en) * 2021-06-30 2021-10-22 武汉钢铁有限公司 High-strength weathering steel with excellent fatigue performance and corrosion resistance and production method thereof

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2974226B2 (en) * 1992-11-11 1999-11-10 川崎製鉄株式会社 Centrifugal casting composite roll
JP3612115B2 (en) * 1995-07-17 2005-01-19 新日本製鐵株式会社 Manufacturing method of ultra high strength steel sheet with excellent low temperature toughness
EP1493828A4 (en) * 2002-03-29 2011-01-05 Nippon Steel Corp High tensile steel excellent in high temperature strength and method for production thereof
CN1946864A (en) * 2004-04-14 2007-04-11 住友金属工业株式会社 Steel product for cargo oil tank
JP4449691B2 (en) * 2004-04-14 2010-04-14 住友金属工業株式会社 Steel material for cargo oil tanks
JP4495668B2 (en) * 2004-11-19 2010-07-07 株式会社神戸製鋼所 High corrosion resistance steel
CN101389782B (en) 2006-02-27 2011-05-25 杰富意钢铁株式会社 Corrosion-resistant steel material for ship and vessel

Also Published As

Publication number Publication date
TWI391499B (en) 2013-04-01
JP2009052136A (en) 2009-03-12
KR101241935B1 (en) 2013-03-11
CN101772583A (en) 2010-07-07
CN101772583B (en) 2012-07-04
KR20130004605A (en) 2013-01-11
TW200912014A (en) 2009-03-16
KR20100023047A (en) 2010-03-03

Similar Documents

Publication Publication Date Title
JP5396758B2 (en) Hot-rolled section steel for ship ballast tank and manufacturing method thereof
JP4525687B2 (en) Corrosion resistant steel for ships
JP5375246B2 (en) Corrosion-resistant steel for crude oil tank and its manufacturing method
JP4687531B2 (en) Steel for crude oil tank and method for producing the same
CN110832099B (en) Structural steel and structure
KR101241932B1 (en) Hot-rolled shape steel for crude oil tanks and process for manufacturing the same
JP5526667B2 (en) Hot rolled section steel for ship ballast tank with excellent corrosion resistance and method for producing the same
WO2007097142A1 (en) Corrosion-resistant steel material for ship and vessel
JP5365187B2 (en) Method for producing marine structural steel with excellent corrosion resistance
TW201814069A (en) Steel for holds of collier and combined use coal/ore ship, and ship
US20230127243A1 (en) Steel sheet, member, and method for producing them
JP5958102B2 (en) Corrosion-resistant steel for ship ballast tank with excellent corrosion resistance and method for producing the same
TWI636142B (en) Steel and ship for ship ballast tanks
JP2011231365A (en) Hot rolled shape steel for vessel and method of manufacturing the same
JP2010229526A (en) Highly-corrosion-resistant painted steel material
JP5515353B2 (en) Hot rolled T-section steel and manufacturing method thereof
JP6690585B2 (en) Steel material and manufacturing method thereof
JP6624130B2 (en) Steel material and method of manufacturing the same
JP7311808B2 (en) Steel plate and its manufacturing method
US20230160032A1 (en) Steel sheet, member, and method for producing them
WO2009017177A1 (en) Hot-rolled shape steel for ships and process for manufacturing the same
JP7350705B2 (en) Low-strength thick steel plate with excellent elongation properties and corrosion resistance
WO2023162507A1 (en) Steel sheet and method for producing same
WO2024101317A1 (en) Clad steel sheet and method for producing same
WO2009041703A1 (en) Hot-rolled shape steel for crude oil tanks and process for manufacturing the same

Legal Events

Date Code Title Description
A621 Written request for application examination

Free format text: JAPANESE INTERMEDIATE CODE: A621

Effective date: 20110128

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20130521

A521 Request for written amendment filed

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20130719

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20130924

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20131007

R150 Certificate of patent or registration of utility model

Ref document number: 5396758

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250