TWI427160B

TWI427160B - Corrosion resistance of the ship with excellent steel

Info

Publication number: TWI427160B
Application number: TW097148250A
Authority: TW
Inventors: Shinji Sakashita; Akihiko Tatsumi; Satoshi Yoshida; Jun Hisamoto
Original assignee: Kobe Steel Ltd
Priority date: 2008-03-04
Filing date: 2008-12-11
Publication date: 2014-02-21
Also published as: JP2009209412A; TW200940724A; CN101525729B; JP5265944B2; CN101525729A; KR20090095487A

Description

耐蝕性優良的船舶用鋼材Steel for ship with excellent corrosion resistance

本發明，是關於作為原油油輪之油槽用結構材的船舶用鋼材，特別是對於在油槽內成為問題的硫化氫或硫磺等所造成的腐蝕，可發揮優良的耐蝕性的船舶用鋼材。The present invention relates to a steel material for a ship which is a structural material for an oil groove of a crude oil tanker, and particularly relates to a steel material for ships which exhibits excellent corrosion resistance against corrosion caused by hydrogen sulfide or sulfur which is a problem in an oil tank.

近年來，在原油輪的油槽(原油油槽)中，明顯存在著由於起因於來自原油的硫磺成分或硫化氫氣體、或滯留在油槽內之含有高濃度氯化物的水分(滯留水)，而使鋼材受到劇烈的局部腐蝕，在早期就造成穿孔這樣的問題。如此之油槽鋼材的腐蝕，由於對原油輪來說有可能招致沉沒這樣重大的事故，因此必須對鋼材實施某種防蝕措施。In recent years, in the oil tank (crude oil tank) of the crude oil wheel, there is a clear presence of moisture (stagnation water) due to a sulfur component derived from crude oil or hydrogen sulfide gas or a high concentration of chloride retained in the oil tank. The steel is subject to severe local corrosion, causing problems such as perforation at an early stage. Corrosion of such oil tank steels requires some kind of anti-corrosion measures for steel because of the possibility of causing heavy accidents such as sinking of crude oil wheels.

在船舶中，藉由採用以焦油環氧樹脂塗料為代表的塗裝來進行的防蝕法，能夠在一定程度上抑制鋼材腐蝕。然而，在環境遮斷性上即使防蝕塗膜還並非完全，可引起水分、鹽分和氧等之腐蝕的化學物質會浸透塗膜，致使某種鋼材腐蝕發生。若在防蝕塗膜的情況下發生鋼材腐蝕時，則由於腐蝕生成物的膨脹壓力導致防蝕塗膜產生膨脹，破壞塗膜進而鋼材露出，致使防蝕作用喪失。In the ship, the corrosion resistance of the steel can be suppressed to some extent by using an anti-corrosion method represented by coating with a tar epoxy paint. However, in the environmental confinement, even if the anti-corrosion coating film is not complete, a chemical substance which causes corrosion of moisture, salt, and oxygen may permeate the coating film, causing corrosion of a certain steel material. When the steel corrosion occurs in the case of the anti-corrosion coating film, the anti-corrosion coating film is expanded due to the expansion pressure of the corrosion product, and the coating film is broken and the steel material is exposed, so that the corrosion prevention effect is lost.

實際上塗膜存在缺陷的可能性很高，由於也有因船舶建造時的碰撞等造成塗膜帶有損傷的情況，因此常會造成裸鋼材露出。另外，鋼材的邊緣部或施工不良部等，形成防蝕塗料的膜厚極薄的部分的情況也不少。如上述般的鋼材露出部會局部性地且集中性地造成鋼材腐蝕，另外，在塗膜極薄的部分，海水於早期就會滲透，在塗膜下產生腐蝕。In fact, there is a high possibility that the coating film is defective, and since the coating film is damaged due to collision during construction of the ship, the bare steel is often exposed. Further, there are many cases in which the edge portion of the steel material or the defective portion of the steel is formed in a portion where the thickness of the anticorrosive paint is extremely thin. The steel exposed portion as described above locally and concentratedly causes corrosion of the steel material, and in the extremely thin portion of the coating film, seawater penetrates at an early stage, and corrosion occurs under the coating film.

另一方面，在船舶中多與塗裝併用的電解防蝕法，是對於壓載艙和外板等的鋼材的防蝕非常有效的防蝕方法。然而，在原油輪的油槽內，有海水並不充分存在的區域，在如此之區域中，由於沒有電化學反應所必須的電解質水溶液，因此電解防蝕效果無法發揮作用。On the other hand, the electrolytic corrosion prevention method which is often used in combination with painting in a ship is an effective anticorrosive method for corrosion prevention of steel materials such as ballast tanks and outer plates. However, in the oil tank of the crude oil wheel, there is a region where seawater is not sufficiently present. In such a region, since there is no aqueous electrolyte solution necessary for the electrochemical reaction, the electrolytic corrosion preventing effect cannot function.

如上所述，現行一般所採用的防蝕方法中，在船舶下水航行後，在比較早期就必須進行修整塗裝、或在船塢進行定期檢查、修補時重新進行塗料塗刷，因而產生維護費用的增加和入船塢期間延長(時間損耗)等之經濟性的損失。As mentioned above, in the current general anti-corrosion method, after the ship is launched into the water, it is necessary to carry out the dressing and coating at the early stage, or to re-paint the paint during the periodic inspection and repair of the shipyard, thus increasing the maintenance cost. Economic loss such as extension (time loss) during docking.

除上述技術以外，至今為止也提出許多藉由化學成分的調整等來使鋼材本身的耐蝕性提升的耐蝕性鋼材(例如，專利文獻1～9)。然而，這些技術所帶來的耐蝕性提高不能說是充分的，對降低上述經濟損失的幫助較小，因此要求更有效的防蝕方法。In addition to the above-described techniques, a plurality of corrosion-resistant steel materials which improve the corrosion resistance of the steel material by adjustment of chemical components or the like have been proposed (for example, Patent Documents 1 to 9). However, the improvement in corrosion resistance brought about by these techniques cannot be said to be sufficient, and it is less helpful in reducing the above economic loss, and therefore requires a more effective anti-corrosion method.

[專利文獻1]日本特開昭63-270444號公報[Patent Document 1] JP-A-63-270444

[專利文獻2]日本特開2004-169048號公報[Patent Document 2] Japanese Patent Laid-Open Publication No. 2004-169048

[專利文獻3]日本特開2006-37201號公報[Patent Document 3] Japanese Laid-Open Patent Publication No. 2006-37201

[專利文獻4]日本特開2007-197757號公報[Patent Document 4] Japanese Patent Laid-Open Publication No. 2007-197757

[專利文獻5]日本特開2007-197758號公報[Patent Document 5] Japanese Patent Laid-Open Publication No. 2007-197758

[專利文獻6]日本特開2007-197759號公報[Patent Document 6] Japanese Patent Laid-Open Publication No. 2007-197759

[專利文獻7]日本特開2007-197760號公報[Patent Document 7] Japanese Patent Laid-Open Publication No. 2007-197760

[專利文獻8]日本特開2007-197761號公報[Patent Document 8] Japanese Patent Laid-Open Publication No. 2007-197761

[專利文獻9]日本特開2007-197762號公報[Patent Document 9] Japanese Patent Laid-Open Publication No. 2007-197762

本發明乃著眼於如上述般之情況而研創，其目的在於，提供一種即使不對鋼材表面實施塗裝或電解防蝕等其他的防蝕手段，在能夠實用的程度上也具有優良的耐蝕性，特別是作為原油輪油槽用之材料為有用的船舶用鋼材。The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an excellent anticorrosive property to a practical extent even if other anticorrosive means such as coating or electrolytic corrosion are not applied to the surface of the steel material, in particular, The material used as the crude oil tank oil tank is a useful steel material for ships.

能夠達成上述目的之本發明的船舶用鋼材，具有如下幾點要旨：分別含有C：0.01～0.20%(此為質量百分比，以下相同)、Si：0.1～0.5%、Mn：0.6～1.8%、P:0.0005～0.02%、S：0.0005～0.01%、Al:0.01～0.10%、Ni：0.1～0.5%、Cr：0.01～0.3%、Ti：0.001～0.05%、Ca：0.0003～0.004%和N：0.0020～0.008%，殘餘部分為由鐵和不可避免的不純物所構成者。The steel material for ships of the present invention which achieves the above object has the following points: C: 0.01 to 0.20% (this is a mass percentage, the same applies hereinafter), Si: 0.1 to 0.5%, and Mn: 0.6 to 1.8%, respectively. P: 0.0005 to 0.02%, S: 0.0005 to 0.01%, Al: 0.01 to 0.10%, Ni: 0.1 to 0.5%, Cr: 0.01 to 0.3%, Ti: 0.001 to 0.05%, Ca: 0.0003 to 0.004%, and N : 0.0020 to 0.008%, and the remainder is composed of iron and unavoidable impurities.

在本發明的船舶用鋼材中，根據需要，(a)滿足Cr的含量[Cr]與S的含量[S]的比値([Cr]/[S])為5～400，並且Cr的含量[Cr]與N的含量[N]的比値([Cr]/[N])為7～100的要件；或(b)含有Cu：0.1～0.5%及/或B：0.00001～0.001%等亦有效，藉由含有這些元素範圍，使船舶用鋼材的特性得到進一步改善。In the steel material for ship of the present invention, (a) the ratio 値 ([Cr] / [S]) satisfying the content [Cr] of Cr and the content [S] of S is 5 to 400, and the content of Cr is required as needed. The ratio of [Cr] to the content of N [N] ([Cr]/[N]) is 7 to 100; or (b) contains Cu: 0.1 to 0.5% and/or B: 0.00001 to 0.001%, etc. It is also effective, and by including these elements, the characteristics of steel for ships are further improved.

另外，在含有Cu時，較佳為滿足：Cu的含量[Cu]與B的含量[B]的比値([Cu]/[B])為300～8000，並且Ni的含量[Ni]與P的含量[P]的比値([Ni]/[P])為15～800之要件。如上述的船舶用鋼材，作為原油輪之油槽的材料特別有用。Further, when Cu is contained, it is preferable that the ratio Cu ([Cu]/[B]) of the content of Cu [Cu] to the content of B [B] is 300 to 8000, and the content of Ni [Ni] is The ratio 値([Ni]/[P]) of the content [P] of P is 15 to 800. The steel material for ships described above is particularly useful as a material for an oil groove of a crude oil wheel.

在本發明的船舶用鋼材中，藉由嚴密地限定化學成分組成，即使不實施塗裝和電解防蝕，在可實用化的程度上也能夠實現耐蝕性優良的船舶用鋼材，如此實施之船舶用鋼材作為原油輪之油槽的材料乃極為有用。In the steel material for ship of the present invention, by strictly limiting the chemical composition, it is possible to realize a ship steel material excellent in corrosion resistance to the extent that it can be practically applied without performing coating and electrolytic corrosion prevention. Steel is extremely useful as a material for oil tanks in crude oil wheels.

本發明者們，為了解決上述課題而反復精心研究。結果發現到，除了C、Si、Mn、P、S、Al等基本成分以外，藉由嚴密地調整Ni、Cr、Ti、Ca、N等元素，能夠實現能夠解決上述課題的船舶用鋼材，從而完成了本發明。The present inventors have repeatedly studied in order to solve the above problems. As a result, it has been found that, in addition to basic components such as C, Si, Mn, P, S, and Al, by strictly adjusting elements such as Ni, Cr, Ti, Ca, and N, it is possible to realize a steel material for ships that can solve the above problems. The present invention has been completed.

本發明的鋼材，為了滿足作為此種鋼材的基本的特性和耐蝕性，必須適當調整C、Si、Mn、P、S、Al、Ni、Cr、Ti、Ca、N等成分。這些成分的範圍限定理由如下。In order to satisfy the basic characteristics and corrosion resistance of the steel material of the present invention, it is necessary to appropriately adjust components such as C, Si, Mn, P, S, Al, Ni, Cr, Ti, Ca, and N. The reasons for limiting the range of these ingredients are as follows.

(C：0.01～0.20%)(C: 0.01 to 0.20%)

C是用於鋼材的強度確保所必要的元素。為了獲得作為石油類儲槽之結構構件的最低強度，即大約400MPa左右(也要根據所使用的鋼材的壁厚)，必須使之含有0.01%以上。但是，若超過0.20%而過剩地含有時，則鋼材的韌性劣化。由於如此，C含量的範圍設在0.01～0.20。尚且，C含量的較佳下限為0.02%，更佳為0.04%以上。另外，C含量之較佳上限為0.19%，更佳為0.18%以下。C is an element necessary for strength assurance of steel. In order to obtain the lowest strength of the structural member as the petroleum storage tank, that is, about 400 MPa (also depending on the wall thickness of the steel used), it must be made 0.01% or more. However, when it exceeds 0.20% and it is contained excessively, the toughness of a steel material will deteriorate. Because of this, the range of the C content is set to 0.01 to 0.20. Further, a preferred lower limit of the C content is 0.02%, more preferably 0.04% or more. Further, the upper limit of the C content is preferably 0.19%, more preferably 0.18% or less.

(Si：0.1～0.5%)(Si: 0.1 to 0.5%)

Si是用來去氧和確保強度所必要的元素，若未滿0.1%時，則不能確保作為結構構件的最低強度。但是若超過0.5%而使之過剩地含有時，則熔接性劣化。還有，Si含量的較佳下限為0.12%，更佳為0.14%以上。另外Si含量較佳上限為0.45%，更佳為0.40%以下。Si is an element necessary for deoxidation and strength, and if it is less than 0.1%, the minimum strength as a structural member cannot be ensured. However, if it exceeds 0.5% and it is contained excessively, the weldability will deteriorate. Further, a preferred lower limit of the Si content is 0.12%, more preferably 0.14% or more. Further, the upper limit of the Si content is preferably 0.45%, more preferably 0.40% or less.

(Mn：0.6～1.8%)(Mn: 0.6 to 1.8%)

Mn亦與Si一樣，是用於去氧和確保強度所必要的元素，若未滿0.6%時，則不能確保作為結構構件的最低強度。但是若超過1.8%而使之過剩地含有，則韌性劣化。還有，Mn含量的較佳下限為0.65%，更佳為0.70%以上。另外Mn含量的較佳上限為1.7%，更佳為1.6%以下。Mn, like Si, is an element necessary for deoxidation and strength, and if it is less than 0.6%, the minimum strength as a structural member cannot be ensured. However, if it exceeds 1.8% and is contained excessively, the toughness deteriorates. Further, a preferred lower limit of the Mn content is 0.65%, more preferably 0.70% or more. Further, the upper limit of the Mn content is preferably 1.7%, more preferably 1.6% or less.

(P：0.0005～0.02%)(P: 0.0005 to 0.02%)

P在熔解時產生作為抑制劑(inhibitor)起作用的磷酸鹽，為提高耐蝕性的元素。為了使其發揮此一作用，P必須含有0.0005%以上。但是，若P含量變得過剩而超過0.02%時，則使韌性和熔接性劣化。由於如此，P含量為0.0005～0.02%。還有，P含量之較佳下限為0.0006%，更佳為0.0007%以上。此外P含量的較佳上限為0.018%，更佳為0.016%以下。When P is melted, it produces a phosphate which acts as an inhibitor and is an element which improves corrosion resistance. In order to make this effect, P must contain 0.0005% or more. However, when the P content is excessive and exceeds 0.02%, the toughness and the weldability are deteriorated. Because of this, the P content is 0.0005 to 0.02%. Further, the preferred lower limit of the P content is 0.0006%, more preferably 0.0007% or more. Further, the upper limit of the P content is preferably 0.018%, more preferably 0.016% or less.

(S：0.0005～0.01%)(S: 0.0005 to 0.01%)

S是具有藉由極微量的存在而具有提高耐蝕性之作用的元素。為了發揮來自S的耐蝕性提升效果，必須使之含有0.0005%以上。但是，若S含量變得過剩而超過0.01%時，則會使韌性和熔接性劣化。由於如此，S含量設為0.0005～0.01%。還有，S含量的較佳下限為0.0006%，更佳為0.0007%以上。另外S含量的較佳上限為0.009%，更佳為0.008%以下。S is an element having an effect of improving corrosion resistance by the presence of a very small amount. In order to exert the effect of improving the corrosion resistance from S, it is necessary to contain 0.0005% or more. However, when the S content is excessive and exceeds 0.01%, the toughness and the weldability are deteriorated. Because of this, the S content is set to 0.0005 to 0.01%. Further, a preferred lower limit of the S content is 0.0006%, more preferably 0.0007% or more. Further, the upper limit of the S content is preferably 0.009%, more preferably 0.008% or less.

(Al：0.01～0.10%)(Al: 0.01 to 0.10%)

Al亦與Si或Mn一樣，是用於去氧和確保強度所必要的元素，若其含量未滿0.01%時，則無法發揮去氧的效果。但是，若含有超過0.10%，則會損害熔接性。由於如此，Al含量設為0.01～0.10%。還有，Al含量之較佳下限為0.012%，更佳為0.015%以上。另外，Al含量的較佳上限為0.09%，更佳為0.08%以下。Al, like Si or Mn, is an element necessary for deoxidation and strength, and if the content is less than 0.01%, the effect of deoxidation cannot be exhibited. However, if it contains more than 0.10%, the weldability will be impaired. Because of this, the Al content is set to 0.01 to 0.10%. Further, a preferred lower limit of the Al content is 0.012%, more preferably 0.015% or more. Further, the upper limit of the Al content is preferably 0.09%, more preferably 0.08% or less.

(Ni：0.1～0.5%)(Ni: 0.1 to 0.5%)

Ni是對耐蝕性提高有效的元素。特別是Ni具有抑制在防蝕塗膜下產生腐蝕反應的作用，發揮出抑制在塗裝的薄膜部分等容易產生之塗膜下腐蝕所帶來的塗膜膨脹的效果。另外，Ni還可發揮出使P的抑制劑效果增大的作用。為了使之發揮如此之效果，必須使Ni含有0.1%以上，但是若過剩地含有時，由於熔接性或熱加工性會劣化，因此必須設在0.5%以下。還有，Ni含量的較佳下限為0.12%，較佳上限為0.45%。Ni is an element effective for improving corrosion resistance. In particular, Ni has an effect of suppressing the occurrence of a corrosion reaction under the anti-corrosive coating film, and exhibits an effect of suppressing swelling of the coating film due to corrosion under the coating film which is likely to occur in the film portion to be coated. Further, Ni can also exert an effect of increasing the inhibitor effect of P. In order to achieve such an effect, Ni must be contained in an amount of 0.1% or more. However, when it is excessively contained, the weldability or hot workability is deteriorated, so it is necessary to set it to 0.5% or less. Further, a preferred lower limit of the Ni content is 0.12%, and a preferred upper limit is 0.45%.

(Cr：0.01～0.3%)(Cr: 0.01 to 0.3%)

Cr為使鏽緻密化，是提高耐蝕性有效的元素。尤其Cr是藉由與S或N之共存而表現出優良耐蝕性的元素。另外，適量的Cr對提高鋼材的韌性有效，也是用於得到作為船舶用鋼材所必要的機械性特性的元素。為了發揮此等效果，Cr必須要含有0.01%以上。然而，若Cr過剩地含有時，則熔接性和加工性會劣化，因此必須設為0.3%以下。還有，Cr含量的較佳下限為0.02%，更佳為0.05%以上。另外，Cr含量的較佳上限為0.28%，更佳為0.26%以下。Cr is an element which is effective for improving corrosion resistance by densifying rust. In particular, Cr is an element which exhibits excellent corrosion resistance by coexistence with S or N. Further, an appropriate amount of Cr is effective for improving the toughness of the steel material, and is also an element for obtaining mechanical properties necessary for the steel material for ships. In order to exert such effects, Cr must be contained in an amount of 0.01% or more. However, when Cr is excessively contained, the weldability and workability are deteriorated, so it is necessary to set it to 0.3% or less. Further, a preferred lower limit of the Cr content is 0.02%, more preferably 0.05% or more. Further, the upper limit of the Cr content is preferably 0.28%, more preferably 0.26% or less.

(Ti：0.001～0.05%)(Ti: 0.001 to 0.05%)

Ti是對提升耐蝕性有效的元素。另外，Ti具有使在氯化物腐蝕環境中產生的鏽緻密化的作用，為抑制塗膜傷部之腐蝕促進的元素。為了發揮此一效果，必須使Ti含有0.001%以上，但若是超過0.05%而過剩含有時，則會使熔接性和加工性劣化。還有，Ti含量的較佳下限為0.005%，較佳上限為0.04%。Ti is an effective element for improving corrosion resistance. Further, Ti has an action of densifying rust generated in a chloride corrosive environment, and is an element for suppressing corrosion promotion of the coating film. In order to exhibit such an effect, Ti must be contained in an amount of 0.001% or more. However, if it is excessively contained in excess of 0.05%, the weldability and workability are deteriorated. Further, a preferred lower limit of the Ti content is 0.005%, and a preferred upper limit is 0.04%.

(Ca：0.0003～0.004%)(Ca: 0.0003 to 0.004%)

Ca是對提升耐蝕性有效的元素。另外，Ca還具有緩和腐蝕前端的pH降低的作用，可發揮抑制因pH降低所造成之腐蝕促進的效果，對表現耐蝕性有效。如此之效果，係藉由使Ca含有0.0003%以上而得到有效地發揮，但若超過0.004%而過剩地使之含有時，則使熔接性和加工性會劣化。還有，Ca含量的較佳下限為0.0005%，較佳上限為0.0035%。Ca is an effective element for improving corrosion resistance. Further, Ca also has an effect of alleviating the pH lowering of the corrosion end, and exhibits an effect of suppressing corrosion promotion due to a decrease in pH, and is effective for exhibiting corrosion resistance. When Ca is contained in an amount of 0.0003% or more, it is effectively exhibited. However, when it exceeds 0.004% and is excessively contained, the weldability and workability are deteriorated. Further, a preferred lower limit of the Ca content is 0.0005%, and a preferred upper limit is 0.0035%.

(N：0.0020～0.008%)(N: 0.0020 to 0.008%)

N是藉由與Cr共存而使耐蝕性提升的元素。為了發揮來自N的耐蝕性提升效果，必須使之含有0.002%以上。但是，若N含量過剩而超過0.008%時，則固溶N量會增加而會對鋼材的延展性和韌性造成不良影響。還有，N含量的較佳下限為0.0025%，更佳為0.003%以上。另外N含量的較佳上限為0.0075%，更佳為0.007%以下。N is an element which improves corrosion resistance by coexisting with Cr. In order to exert the effect of improving the corrosion resistance from N, it is necessary to contain 0.002% or more. However, when the N content is excessive and exceeds 0.008%, the amount of solid solution N increases, which adversely affects the ductility and toughness of the steel material. Further, a preferred lower limit of the N content is 0.0025%, more preferably 0.003% or more. Further, the upper limit of the N content is preferably 0.0075%, more preferably 0.007% or less.

本發明的船舶用鋼材的基本成分如下，其殘餘部分是由鐵和不可避免的不純物所構成者。作為不可避免的不純物，可列舉出O、H、V、Nb、Mo、W等，這些元素在不損害鋼材特性的程度下也可以含有。但是，這些不可避免的不純物，其合計藉由抑制在0.05%以下，較佳為抑制在0.04%以下，可以使本發明的船舶用鋼材的耐蝕性表現效果極大化。The basic component of the steel material for ships of the present invention is as follows, and the remaining portion is composed of iron and unavoidable impurities. Examples of the unavoidable impurities include O, H, V, Nb, Mo, and W. These elements may be contained to such an extent that the properties of the steel material are not impaired. However, the total unavoidable impurities are suppressed to 0.05% or less, preferably 0.04% or less, and the corrosion resistance performance effect of the steel material for ship of the present invention can be maximized.

另外，在本發明的船舶用鋼材中，除上述成分以外，依據需要還可含有Cu：0.1～0.5%及/或B：0.00001～0.001%亦為有效，據此將進一步改善船舶用鋼材的特性。Further, in the steel material for ship of the present invention, in addition to the above-mentioned components, it is also effective to further contain Cu: 0.1 to 0.5% and/or B: 0.00001 to 0.001%, thereby further improving the characteristics of the steel material for ships. .

(Cu：0.1～0.5%及/或B：0.00001～0.001%)(Cu: 0.1 to 0.5% and/or B: 0.00001 to 0.001%)

Cu及B是對提升耐蝕性有效的元素，特別是使此等元素共存時，可表現出優良的耐蝕性。其中Cu具有的作用是：在塗膜缺陷部，鋼材受到腐蝕時可將所產生的鏽予以微細化，對表現抑制塗膜傷部之腐蝕促進的效果為有用的元素。為了發揮來自Cu之此一效果，較佳是使Cu含有0.1%以上，但是若過剩含有時，則熔接性和熱加工性會劣化，因此較佳為0.5%以下。還有，含有Cu時的更佳下限為0.12%，更佳的上限為0.45%。Cu and B are elements effective for improving corrosion resistance, and in particular, when these elements coexist, excellent corrosion resistance can be exhibited. Among them, Cu has a function of refining the generated rust when the steel material is corroded in the coating film defect portion, and is useful as an element for exhibiting an effect of suppressing corrosion of the coating film. In order to exhibit such an effect from Cu, Cu is preferably contained in an amount of 0.1% or more. However, when it is excessively contained, the weldability and hot workability are deteriorated, so that it is preferably 0.5% or less. Further, a lower limit of the content of Cu is preferably 0.12%, and a more preferable upper limit is 0.45%.

另一方面，B除了發揮耐蝕性之外，因為使淬火性提高，所以也是對提升鋼材強度有效的元素。為了發揮此一效果，使B含有0.00001%以上為佳。但是，若B含量超過0.001%而成為過剩時，則由於母材韌性會劣化，故不理想。還有，B含量的更佳下限為0.00003%，進一步較佳為0.00005%以上。另外，B含量的更佳上限為0.0008%，進一步較佳為0.0006%以下。On the other hand, in addition to exhibiting corrosion resistance, B is an element effective for improving the strength of the steel because it improves the hardenability. In order to exert this effect, it is preferable to make B contain 0.00001% or more. However, when the B content exceeds 0.001% and becomes excessive, the base material toughness is deteriorated, which is not preferable. Further, a lower limit of the B content is more preferably 0.00003%, still more preferably 0.00005% or more. Further, a more preferable upper limit of the B content is 0.0008%, and further preferably 0.0006% or less.

在本發明的船舶用鋼材中，為了發揮優良的耐蝕性，不僅必須如上述般地調整化學成分組成，依據必要，還應適當地控制Cr的含量[Cr]與S的含量[S]的比値([Cr]/[S])，以及Cr的含量[Cr]與N的含量[N]的比値([Cr]/[N])為佳。另外，依據必要而含有Cu之情形時，亦宜適當控制Cu的含量[Cu]與B的含量[B]的比値([Cu]/[B])，並且適當控制Ni的含量[Ni]與P的含量[P]的比値([Ni]/[P])為佳。這些範圍的限定理由如下。In the steel material for ship of the present invention, in order to exhibit excellent corrosion resistance, it is necessary to adjust the chemical composition as described above, and to appropriately control the ratio of the Cr content [Cr] to the S content [S] as necessary.値([Cr]/[S]), and the ratio Cr([Cr]/[N]) of the content [Cr] of Cr to the content [N] of N is preferable. In addition, when Cu is contained as necessary, it is also appropriate to appropriately control the ratio Cu([Cu]/[B]) of the content of Cu [Cu] to the content of B [B], and appropriately control the content of Ni [Ni] The ratio 値([Ni]/[P]) to the content [P] of P is preferred. The reasons for limiting these ranges are as follows.

([Cr]/[S]：5～400)([Cr]/[S]: 5 to 400)

藉由使Cr和S以適當的比率共存，Cr的硫化物可抑制腐蝕反應而發揮出使耐蝕性(特別是裸材規格下之鋼材的耐點蝕性)提升的效果。為了發揮此一效果，上述比値([Cr]/[S])至少為5以上為佳。然而，若該比値([Cr]/[S])過大而超過400時，由於Cr硫化物的產生不充分，因此得不到充分的耐蝕性提升效果。還有，上述比値([Cr]/[S])之更佳下限為10，更佳上限為350。By coexisting Cr and S at an appropriate ratio, the sulfide of Cr suppresses the corrosion reaction and exhibits an effect of improving corrosion resistance (especially pitting resistance of a steel material under a bare material specification). In order to exert this effect, the above ratio [([Cr]/[S]) is preferably at least 5 or more. However, if the specific enthalpy ([Cr]/[S]) is too large and exceeds 400, the generation of Cr sulfide is insufficient, so that a sufficient corrosion-improving effect cannot be obtained. Further, the above lower limit of the ratio 値([Cr]/[S]) is 10, and the upper limit is more preferably 350.

([Cr]/[N]：7～100)([Cr]/[N]: 7 to 100)

藉由使Cr及N以適當的比率共存，Cr的氮化物可抑制腐蝕反應而發揮出使耐蝕性提升的效果。為了發揮此一效果，上述比値([Cr]/[N])至少為7以上較佳。然而，若該比値([Cr]/[N])過大而超過100時，由於Cr氮化物的產生不充分，因此得不到充分的耐蝕性提升效果。還有，上述比値([Cr]/[N])之更佳下限為10，更佳上限為90。By coexisting Cr and N at an appropriate ratio, the nitride of Cr suppresses the corrosion reaction and exhibits an effect of improving corrosion resistance. In order to exert this effect, the above ratio [([Cr]/[N]) is preferably at least 7 or more. However, when the specific enthalpy ([Cr]/[N]) is too large and exceeds 100, the generation of Cr nitride is insufficient, so that a sufficient corrosion-improving effect cannot be obtained. Further, the above lower limit of the ratio 値([Cr]/[N]) is 10, and the upper limit is more preferably 90.

([Cu]/[B]：300～8000)([Cu]/[B]: 300 to 8000)

Cu及B可依需要共存而含有，但這種情況下藉由使Cu和B以適當的比率共存，Cu的硼化物抑制腐蝕反應而發揮出進一步提升耐蝕性(特別是塗裝耐蝕性)的效果。為了發揮此一效果，上述比値([Cu]/[B])為300以上為佳。然而，若該比値([Cu]/[B])增大而超過8000時，由於Cu的硼化物的產生不充分，因此無法得到耐蝕性提升效果。還有，上述比値([Cu]/[B])的更佳下限為400，更佳上限為7000。Cu and B may be contained as needed, but in this case, Cu and B are coexisted at an appropriate ratio, and the boride of Cu suppresses the corrosion reaction and exhibits further improvement in corrosion resistance (especially coating corrosion resistance). effect. In order to exert this effect, the above ratio [([Cu]/[B]) is preferably 300 or more. However, when the ratio 値([Cu]/[B]) is increased to more than 8000, the generation of boride of Cu is insufficient, so that the corrosion resistance improving effect cannot be obtained. Further, the above lower limit of the ratio 値([Cu]/[B]) is 400, and the upper limit is 7000.

([Ni]/[P]：15～800)([Ni]/[P]: 15 to 800)

藉由使Ni及P以適當的比率共存，Ni的磷化合物可抑制腐蝕反應而發揮出使耐蝕性(特別是塗裝耐蝕性)提升的效果。為了發揮此一效果，上述比値([Ni]/[P])至少為15以上為佳。然而，若該比値([Ni]/[P])增大而超過800時，由於Ni的磷化合物的產生不充分，因此難以得到耐蝕性提升效果。還有，上述比値([Ni]/[P])之更佳下限為20，更佳上限為700。By allowing Ni and P to coexist at an appropriate ratio, the phosphorus compound of Ni suppresses the corrosion reaction and exhibits an effect of improving corrosion resistance (especially coating corrosion resistance). In order to exert this effect, the above ratio [([Ni]/[P]) is preferably at least 15 or more. However, when the specific enthalpy ([Ni]/[P]) is increased to exceed 800, the generation of the phosphorus compound of Ni is insufficient, so that it is difficult to obtain the effect of improving the corrosion resistance. Further, the above lower limit of the ratio 値([Ni]/[P]) is 20, and the upper limit is more preferably 700.

本發明的船舶用鋼材，例如能夠藉由以下的方法製造。首先，對於從轉爐或電氣爐出鋼到盛鋼桶中的鋼水，使用真空循環脫氣裝置(RH裝置)進行包括成分調整、溫度調整的二次精煉。其後，利用連續鑄造法、鑄錠法等通常的鑄造方法而成為鋼塊(鑄錠)。作為這時的去氧形式，從機械特性和熔接性的觀點來看，推薦使用鎮靜鋼較佳，更佳為Al鎮靜鋼。The steel material for ships of the present invention can be produced, for example, by the following method. First, for the molten steel which is tapped from the converter or the electric furnace to the ladle, a secondary refining including composition adjustment and temperature adjustment is performed using a vacuum circulation deaerator (RH apparatus). Thereafter, it is a steel block (ingot) by a usual casting method such as a continuous casting method or an ingot casting method. As the oxygen-removing form at this time, it is preferable to use a killed steel from the viewpoint of mechanical properties and weldability, and more preferably an Al-killed steel.

接著，將得到的鋼錠加熱至1000～1300℃的溫度區域後，進行熱軋，製成為期望的形狀為佳。將此時的熱軋結束溫度控制在650～850℃，將熱軋結束至500℃的冷卻速度控制在0.1～15℃/秒的範圍，藉此得到預定的強度特性。Next, the obtained ingot is heated to a temperature range of 1000 to 1300 ° C, and then hot rolled to obtain a desired shape. The hot rolling end temperature at this time is controlled to 650 to 850 ° C, and the cooling rate from the end of hot rolling to 500 ° C is controlled to be in the range of 0.1 to 15 ° C / sec, whereby predetermined strength characteristics are obtained.

本發明的船舶用鋼材，基本上即使不實施塗裝，鋼材本身也會發揮出優良的耐蝕性，但依據需要，也可以與後述的實施例所述的焦油環氧樹脂塗料、或其以外的代表的重防蝕塗裝、富鋅漆(zinc rich paint)、預塗底漆(shop primer)等其他的防蝕方法併用。實施有如此之防蝕塗裝時，如後述的實施例所示，塗裝膜本身的耐蝕性(塗裝耐蝕性)也良好。The steel material for ship of the present invention basically exhibits excellent corrosion resistance even if it is not applied, but may be tar-based epoxy resin paint described in Examples below, or other than necessary. Represented by other anti-corrosion coatings, zinc rich paint, shop primer and other anti-corrosion methods. When such an anti-corrosion coating is carried out, the corrosion resistance (coating corrosion resistance) of the coating film itself is also good as shown in the examples described later.

以下，列舉實施例更具體地說明本發明，但本發明並不受下述實施例所限制，在符合前後述的宗旨的範圍內當然也可以加以變更實施，此等皆包含在本發明的技術性範圍內。Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples, and may be modified and implemented within the scope of the above-described embodiments, and these are all included in the technology of the present invention. Within the scope of sex.

[實施例][Examples]

製作下述第1表所示的化學成分組成的鋼材。此時的製作方法為：首先以轉爐熔製，藉由連續鑄造製為鋼錠。將得到的鋼錠加熱至1150℃後進行熱軋而製成板厚19mm的鋼原材料。此時的熱軋結束溫度設在650～850℃的範圍，將熱軋結束至500℃的冷卻速度，在0.1～15℃/秒的範圍內適宜調整。提供下述之試驗的試片，全部最終皆為100×100×10(mm)，是從上述鋼原材料切割下(試驗片A)。試驗片A的外觀形狀顯示於第1圖中。A steel material having the chemical composition shown in Table 1 below was produced. The production method at this time is: first, melting in a converter, and forming into a steel ingot by continuous casting. The obtained ingot was heated to 1,150 ° C and then hot rolled to obtain a steel material having a thickness of 19 mm. The hot rolling completion temperature at this time is set in the range of 650 to 850 ° C, and the cooling rate from the end of hot rolling to 500 ° C is appropriately adjusted in the range of 0.1 to 15 ° C / sec. The test pieces which were subjected to the following tests, all of which were 100 × 100 × 10 (mm), were cut from the above-mentioned steel raw material (test piece A). The appearance of the test piece A is shown in Fig. 1.

用來評估在無塗裝狀態下之耐蝕性的試片，係以濕式旋轉研磨機(研磨紙：#600)對試驗面(100×100mm的面)實施研磨，進行水洗和丙酮清洗之後提供試驗。還有，在耐腐蝕試驗中，為了防止試驗面以外腐蝕，而對試驗面以外塗佈矽酮密封劑來實施被覆。For the test piece used to evaluate the corrosion resistance in the uncoated state, the test surface (100×100 mm surface) was ground by a wet rotary grinder (grinding paper: #600), and then provided after washing with water and acetone. test. Further, in the corrosion resistance test, in order to prevent corrosion other than the test surface, the enamel sealant was applied to the test surface to perform coating.

為了進行塗裝耐蝕性的評估，按以下步驟對一部分的試片實施塗裝。首先，噴沙加工整個面，水洗和丙酮清洗之後，塗佈富鋅漆使之平均厚度為15μm(±3μm)，在乾燥器內使之乾燥24小時以上。其後，將變性環氧樹脂塗料藉由無空氣噴塗以厚度350μm(±20μm)進行塗佈。塗膜乾燥後，為了調查：在用來防蝕的塗膜上帶傷使母材的鋼材外露的情況下的腐蝕進展程度，因而亦準備了試驗片B，其在試驗面(100×100mm的面)上形成有用切割刀所形成之長100mm、寬約0.5mm之到達母材的1條割傷(第2圖)。In order to evaluate the corrosion resistance of the coating, a part of the test piece was applied as follows. First, sandblasting was applied to the entire surface, and after washing with water and acetone, the zinc-rich paint was applied to have an average thickness of 15 μm (±3 μm), which was dried in a desiccator for 24 hours or more. Thereafter, the denatured epoxy resin coating was applied by airless spraying at a thickness of 350 μm (±20 μm). After the coating film was dried, in order to investigate the degree of corrosion progress in the case where the coating material for corrosion prevention caused the steel material of the base material to be exposed, the test piece B was prepared, and the test surface (100 × 100 mm surface) was prepared. A cut of the base material formed by the cutting blade and having a length of about 0.5 mm and a width of about 0.5 mm is formed on the base material (Fig. 2).

在所述第1表所示的各化學成分組成的供試材料中，準備試驗片A及試驗片B提供腐蝕試驗。在此的腐蝕試驗方法如下。In the test materials having the chemical composition compositions shown in the first table, test pieces A and test pieces B were prepared to provide a corrosion test. The corrosion test method here is as follows.

(腐蝕試驗方法)(corrosion test method)

實施模擬原油輪之油槽內的腐蝕試驗，並評估了耐蝕性。如第3圖以模式化地顯示，將科威特產的原油及用以腐蝕促進的人造海水放入密閉的試驗容器內，將上述製作的試驗片(A、B)作為試片分別設置在試驗容器內的底部和頂部的各處。設置在底部及頂部的試片是分別用以評估油槽的底板以及上甲板的腐蝕。在此，人造海水與原油的體積比為1：1。Corrosion tests in oil tanks simulating crude oil wheels were carried out and corrosion resistance was evaluated. As shown in Fig. 3, the crude oil produced in Kuwait and the artificial seawater for corrosion promotion were placed in a closed test container, and the test pieces (A, B) prepared above were set as test pieces in the test container. Inside the bottom and top of the place. The test pieces set at the bottom and top are used to evaluate the corrosion of the bottom and upper deck of the oil tank, respectively. Here, the volume ratio of artificial seawater to crude oil is 1:1.

另外，在試驗容器內，進行實船油槽內之模擬氣體的通氣，其組成為：5vol%O₂ -13vol%CO₂ -0.01vol%SO₂ -0.30vol%H₂ S-bal‧N₂ 。從試驗容器的外部使用加熱器進行加熱，使氣相部溫度在50℃保持20小時後，利用自然冷卻使溫度降低至25℃並保持在25℃，以如此的溫度循環(合計24小時)為1循環，每天反復進行。藉由進行如此之溫度循環，在氣相部係與實船的儲槽同樣因結露而造成腐蝕發生。使試驗期間為1年來實施試驗。供試的試片個數，為對於各鋼種(第1表的No.1～30)之各個、各試驗條件(頂部和底部)各實施5片(試驗片A、B分別各5片)。Further, in the test vessel, the ventilation of the simulated gas in the actual ship oil tank was carried out, and the composition thereof was: 5 vol% O _{2 -} 13 vol% CO _{2 -} 0.01 vol% SO _{2 -} 0.30 vol% H ₂ S-bal ‧ N ₂ . Heating was performed from the outside of the test vessel using a heater, and after the temperature of the gas phase portion was maintained at 50 ° C for 20 hours, the temperature was lowered to 25 ° C by natural cooling and maintained at 25 ° C, and such a temperature cycle (total 24 hours) was 1 cycle, repeated every day. By performing such a temperature cycle, corrosion occurs in the gas phase portion and the reservoir of the actual ship due to dew condensation. The test was carried out for one year during the test period. The number of test pieces to be tested was 5 pieces for each of the steel types (No. 1 to 30 of the first table) and for each test condition (top and bottom) (5 pieces for each of the test pieces A and B).

試片的測定項目及評估標準，係如下述第2表所示。對於安裝在試驗容器頂部的無塗裝試片(試驗片A)，測量試驗前後的重量變化，求得提供試驗之5片的平均値。對於安裝在試驗容器底部的無塗裝試樣(試驗片A)，以深度規測量局部腐蝕(點腐蝕)的深度，以各提供試驗的5個試驗片之中之最深者作為最大點腐蝕深度。還有，在試驗後，藉由噴水法除去腐蝕產生物之後，進行重量測量或點腐蝕深度的測量。The measurement items and evaluation criteria of the test piece are shown in Table 2 below. For the uncoated test piece (test piece A) mounted on the top of the test container, the change in weight before and after the test was measured, and the average enthalpy of the five pieces of the test was obtained. For the uncoated sample (test piece A) installed at the bottom of the test vessel, the depth of local corrosion (pitting corrosion) was measured with a depth gauge, and the deepest of the five test pieces provided for each test was used as the maximum pitting depth. . Further, after the test, the corrosion measurement was removed by a water spray method, and the measurement of the weight or the depth of the pitting corrosion was performed.

另外，對於安裝在試驗容器的頂部及底部的塗裝試樣(試驗片B)，皆用游標卡尺測量塗膜的膨脹寬度(與割傷成垂直方向的膨脹寬度)，依據各個提供試驗的5個試驗片之中之最大値(最大膨脹寬度)評估了塗膜傷部耐蝕性(塗裝耐蝕性)。將試驗結果統括顯示在下述第3表中。In addition, for the coated samples (test piece B) mounted on the top and bottom of the test container, the splay caliper was used to measure the expansion width of the coating film (expansion width perpendicular to the cut), according to the five provided for each test. The maximum flaw (maximum expansion width) in the test piece evaluated the corrosion resistance (coating corrosion resistance) of the coating film. The test results are collectively shown in Table 3 below.

由這些結果能夠進行如下考察。首先，可知使用了不含作為本發明的鋼板中之必須的合金成分之Ni、Cr、Ti等之鋼材(習知的普通鋼)的No.1，在任一條件下均無法發揮預定的耐蝕性。These results can be examined as follows. First, it is understood that No. 1 using a steel material (known ordinary steel) of Ni, Cr, Ti or the like which does not contain an alloy component which is an essential component in the steel sheet of the present invention, does not exhibit predetermined corrosion resistance under any of the conditions. .

試驗No.2其Ni含量，試驗No.3其P含量、試驗No.4其S含量、試驗No.5其N含量分別低於在本發明所規定的範圍，耐蝕性提升效果不充分，為不能滿足作為原油輪油槽用鋼材者。Test No. 2 has a Ni content, Test No. 3, P content, Test No. 4, S content, and Test No. 5, and N content thereof are respectively lower than the range specified in the present invention, and the corrosion resistance improving effect is insufficient. Can not meet the steel as a crude oil tank oil tank.

相對於此，試驗No.6~30者，為滿足在本發明所規定的化學成分組成者，可知任一者耐蝕性均提升到“○”以上的水準。特別是滿足比値([Cr]/[S])與([Cr]/[N])之兩方要件者，在(試驗No.10～14)中，可知裸材規格下的耐蝕性提高到“◎”。還有，No.15～17者，為脫離比値([Cr]/[S])與([Cr]/[N])之較佳要件者，與滿足該等要件者(試驗No.10～14)相比，底部耐蝕性(裸材規格)稍有降低。On the other hand, in the test Nos. 6 to 30, in order to satisfy the chemical composition specified in the present invention, it is understood that the corrosion resistance is improved to a level of "○" or more. In particular, in the case of satisfying the two requirements of 値([Cr]/[S]) and ([Cr]/[N]), in (Test No. 10 to 14), it is known that the corrosion resistance under the bare material specification is improved. Go to "◎". In addition, those who are No. 15 to 17 are the preferred ones for the deviation ratio [ ([Cr]/[S]) and ([Cr]/[N]), and those who satisfy the requirements (Test No. 10) ~14) The bottom corrosion resistance (bare material specification) is slightly lower.

另外，使之含有Cu或B，得知對耐蝕性提升有效(No.20～30)。此外，將比値([Cr]/[S])及([Cr]/[N])之雙方予以適當地調整過者(No.24～26、29、30)可知其塗裝耐蝕性飛躍性地提升。Further, it was found to contain Cu or B, and it was found to be effective for improving corrosion resistance (No. 20 to 30). In addition, if both of the 値([Cr]/[S]) and ([Cr]/[N]) are appropriately adjusted (No. 24 to 26, 29, 30), the coating corrosion resistance is leap. Sexually improved.

第1圖是顯示使用於耐蝕性試驗之試驗片A之外觀形狀的說明圖。Fig. 1 is an explanatory view showing the appearance of the test piece A used in the corrosion resistance test.

第2圖是顯示使用於耐蝕性試驗之試驗片B之外觀形狀的說明圖。Fig. 2 is an explanatory view showing the appearance of the test piece B used for the corrosion resistance test.

第3圖是用以說明耐蝕性試驗之實施狀況的模式圖。Fig. 3 is a schematic view for explaining the state of implementation of the corrosion resistance test.

Claims

一種耐蝕性優良的船舶用鋼材，其特徵為：分別含有C：0.01~0.20%(指質量%，以下相同)、Si：0.1~0.5%、Mn：0.6~1.8%、P：0.0005~0.02%、S：0.0005~0.01%、Al：0.01~0.10%、Ni：0.1~0.5%、Cr：0.01~0.3%、Ti：0.001~0.05%、Ca：0.0003~0.004%以及N：0.0020~0.008%，同時含有Cu：0.1~0.5%及/或B：0.00001~0.001%，殘餘部分是鐵和不可避免的不純物，並且Cu的含量〔Cu〕與B的含量〔B〕的比值〔Cu〕/〔B〕為300~8000，並且Ni的含量〔Ni〕與P的含量〔P〕的比值〔Ni〕/〔P〕為15~800。 A ship steel material excellent in corrosion resistance, characterized by containing C: 0.01 to 0.20% (referring to mass%, the same below), Si: 0.1 to 0.5%, Mn: 0.6 to 1.8%, and P: 0.0005 to 0.02%. , S: 0.0005~0.01%, Al: 0.01~0.10%, Ni: 0.1~0.5%, Cr: 0.01~0.3%, Ti: 0.001~0.05%, Ca: 0.0003~0.004%, and N: 0.0020~0.008%, It also contains Cu: 0.1~0.5% and/or B: 0.00001~0.001%, the residual part is iron and unavoidable impurities, and the ratio of Cu content [Cu] to B content [B] [Cu]/[B 〕 is 300 to 8000, and the ratio [Ni] / [P] of the content of Ni [Ni] to the content of P [P] is 15 to 800.

如申請專利範圍第1項之船舶用鋼材，其中，Cr的含量〔Cr〕與S的含量〔S〕的比值〔Cr〕/〔S〕為5~400，並且Cr的含量〔Cr〕與N的含量〔N〕的比值〔Cr〕/〔N〕為7~100。 For example, in the steel material for ships of claim 1, wherein the ratio [Cr]/[S] of the content of Cr [Cr] to the content of S [S] is 5 to 400, and the content of Cr [Cr] and N The ratio [Cr] / [N] of the content [N] is 7 to 100.

如申請專利範圍第1或2項之船舶用鋼材，其中，上述船舶用鋼材是作為原油油輪之油槽的原材料來使用。 The steel material for ships of claim 1 or 2, wherein the steel material for ships is used as a raw material of an oil tank of a crude oil tanker.