WO2010087509A1 - 原油タンク用耐食鋼材とその製造方法ならびに原油タンク - Google Patents
原油タンク用耐食鋼材とその製造方法ならびに原油タンク Download PDFInfo
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- 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
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- 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
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- 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
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- 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
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
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- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
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- 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
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
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- 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
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- 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
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- 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
- C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
Definitions
- the present invention is applied to a tank for transporting or storing an oil tank of a crude oil tanker or crude oil (hereinafter referred to collectively as a “crude oil tank”).
- a crude oil tank for transporting or storing an oil tank of a crude oil tanker or crude oil
- the present invention relates to a steel material capable of reducing local corrosion that occurs in a bottom plate of a crude oil tank.
- the steel material for crude oil tanks of the present invention includes a thick steel plate, a thin steel sheet, and a shaped steel.
- H 2 S is oxidized using iron rust generated by corrosion as a catalyst, and solid S is formed in layers in the iron rust, and these corrosion products (corrosion products). ) Deposits on the bottom of the crude oil tank because it easily peels off and falls off. Therefore, in the inspection at the dock every 2.5 years, the maintenance of the upper part of the tank (maintenance and repair) and the recovery of the deposited material (deposited material) at the bottom of the tank are performed at a great expense. It is.
- the bottom plate of a tanker's crude oil tank has a corrosion inhibition function of the crude oil itself and a protective coating derived from crude oil formed on the inner surface of the crude oil tank (hereinafter referred to as “oil coat”). It was thought that the steel material used did not corrode due to the corrosion-inhibiting action of. However, recent studies have revealed that bowl-shaped local corrosion (pitting corrosion) occurs in the steel plate of the tank bottom plate.
- the most effective method of suppressing the above-mentioned general corrosion and local corrosion is a method in which heavy coating is applied to the surface of the steel material and the steel material is shielded from the corrosive environment.
- the coating area of the crude oil tank is enormous.
- the coating film needs to be repainted once every 10 years due to deterioration of the coating film, a large cost is incurred for inspection and painting.
- corrosion is promoted on the damaged part of the heavy-painted coating film in the crude oil tank environment.
- Patent Document 1 adds appropriate amounts of Si, Mn, P, S and Ni: 0.05 to 3% to steel containing C: 0.01 to 0.3% by mass.
- a corrosion resistant steel for cargo oil tanks having improved resistance to general corrosion and local corrosion by selectively adding Mo, Cu, Cr, W, Ca, Ti, Nb, V, and B is disclosed.
- the Cr content exceeds 0.05 mass%, the overall corrosion resistance and pitting corrosion resistance deteriorate significantly, so the Cr content is 0.05 mass%. % Or less is disclosed.
- Patent Document 2 discloses that steel containing C: 0.001 to 0.2% by mass% and appropriate amounts of Si, Mn, P, S and Cu: 0.01 to 1.5%, Al: 0.001 to 0.3%, N: 0.001 to 0.01% is added, and at least one of Mo: 0.01 to 0.2% or W: 0.01 to 0.5% Has been disclosed, which is excellent in overall corrosion resistance and local corrosion resistance and suppresses the formation of corrosion products containing solid S, and is used for crude oil tanks.
- Patent Document 3 discloses that steels containing C: 0.01 to 0.2% by mass% and appropriate amounts of Si, Mn, P, Ni: 0.01 to 2%, Cu: 0 .05 to 2%, W: 0.01 to 1% is added, and Cr, Al, N, and O are selectively added, and the addition amount of Cu, Ni, and W is further defined by a parameter equation. Discloses a corrosion-resistant steel for cargo oil tanks with improved overall corrosion and local corrosion.
- Patent Document 4 discloses that steel containing C: 0.01 to 0.2% by mass%, an appropriate amount of Si, Mn, P, Cr, Al, and Ni: 0.01 to 1%.
- Cu: 0.05-2%, Sn: 0.01-0.2% are added, and Mo, W, Ti, Zr, Sb, Ca, Mg, Nb, V, and B are selectively added. Accordingly, a corrosion resistant steel for a cargo oil tank having improved resistance to general corrosion and local corrosion is disclosed.
- Patent Documents 3 and 4 consider that the seawater is loaded in the ballast tank outside the cargo oil tank when the crude oil is not loaded, so that both the corrosion resistance in the crude oil corrosion environment and the seawater corrosion environment are compatible.
- This is a technology aimed at.
- these technologies focus on the corrosion resistance of the steel itself as the corrosion resistance after deterioration of the anticorrosive coating on the outer surface of the cargo oil tank against seawater corrosive environments.
- No consideration is given to the improvement of the corrosion resistance in a state where a coating film exists on the surface of the steel material due to the synergistic effect with Zn in the coating, that is, the so-called post-coating corrosion resistance.
- the present invention was developed to solve the above-mentioned problems, and the object thereof is to have a general corrosion resistance excellent when used on an inner surface of a crude oil tank, particularly an upper deck and a side plate, and a crude oil tank. Excellent local corrosion resistance even when used on the bottom plate. In addition, when used in the presence of Zn on the steel surface, it exhibits outstanding overall corrosion resistance and local corrosion resistance.
- An object of the present invention is to provide a steel material for a crude oil tank, a method for producing the same, and a crude oil tank using the steel material.
- the inventors first extracted factors involved in the overall corrosion in the crude oil tank and conducted a corrosion test in which those factors were combined.
- the inert gas enclosed in the crude oil tank for explosion protection contains water vapor. Therefore, condensation occurs on the steel material surface of the inner wall of the tank due to the temperature difference between day and night during voyage.
- inert gas components such as CO 2 (carbon dioxide), O 2 (oxygen), SO 2 (sulfur dioxide), and volatile components from crude oil such as H 2 S (hydrogen sulfide) dissolve and sulfate ions.
- a corrosive acidic solution containing is produced. It is also necessary to consider chloride ions brought in by washing the crude oil tank with seawater. A corrosive acid solution in which these components are dissolved concentrates in the process of increasing the temperature of the steel sheet and causes overall corrosion on the steel sheet surface. Furthermore, using iron rust formed on the steel sheet surface as a catalyst, S (sulfur) is precipitated from H 2 S to form a rust layer in which the iron rust and sulfur are layered, so that the rust layer on the steel sheet surface is brittle and protective. Corrosion proceeds continuously.
- the inventors investigated the influence of various alloy elements on the overall corrosion of the steel sheet surface in an environment where condensed water containing sulfate ions and chloride ions was present.
- the addition of Cu, Cr and Sn densifies the rust layer on the surface of the steel sheet formed in the environment used as a steel material for crude oil tanks, improves the overall corrosion resistance, and also adds W and Sb.
- W and Sb the addition of Cu, Cr and Sn densifies the rust layer on the surface of the steel sheet formed in the environment used as a steel material for crude oil tanks.
- W and Sb Confirmed that it promotes the formation of a dense rust layer and improves the overall corrosion resistance. That is, it has been found that a steel material for a crude oil tank having excellent overall corrosion resistance can be obtained by adding appropriate amounts of W and Sb in addition to Cu, Cr and Sn.
- H 2 S is oxidized and solid S is precipitated.
- the precipitated solid S forms a local battery with the bottom plate of the crude oil tank, causing local corrosion on the steel material surface. This local corrosion is further accelerated and grows in an acidic environment where chloride ions and sulfate ions are present.
- the inventors investigated the influence of various alloy elements on the occurrence of local corrosion in the environment of the low O 2 concentration and the low H 2 S concentration.
- the addition of W densifies the rust layer on the surface of the steel sheet formed in an environment used as a steel material for crude oil tanks and improves local corrosion resistance
- the addition of Sn and Sb It was confirmed that the formation of a dense rust layer was improved and the local corrosion resistance was improved.
- addition of Mo deteriorates the corrosion resistance. That is, by adding appropriate amounts of Sn and Sb in addition to the addition of W and limiting the Mo content, a steel material for a crude oil tank excellent in local corrosion resistance can be obtained.
- the inventors have described that the steel material with the appropriate Cu, Cr, Sn, W, and Sb contents has excellent corrosion resistance even in an unpainted state, but the surface is coated with metal Zn or a Zn compound. It has been found that the coating life can be greatly extended and the overall corrosion resistance and the local corrosion resistance are remarkably improved when applied and used. Further, in the steel material of the present invention, when the influence of the microstructure of the steel on the corrosion resistance was examined, the corrosion resistance can be improved by generating pearlite with an area ratio of 2% or more. I also found. The present invention has been made based on the above findings and further studies.
- the present invention includes C: 0.001 to 0.16 mass%, Si: 1.5 mass% or less, Mn: 0.1 to 2.5 mass%, P: 0.025 mass% or less, S: 0.01 mass%.
- [C], [P], [S], [Cu], [Ni], [Cr], [Mo], and [Sn] in the above formula are the content of each element (mass%).
- the value of A2 defined in (1) is 0 or less.
- the corrosion resistant steel material for crude oil tanks of the present invention may be one or two selected from W: 0.001 to 0.5 mass% and Sb: 0.005 to 0.3 mass%.
- the corrosion resistant steel material for crude oil tanks of the present invention further includes Nb: 0.002-0.1 mass%, V: 0.002-0.1 mass%, Ti: 0.001-0. 1 mass% and B: It contains 1 type or 2 or more types chosen from 0.01 mass% or less, It is characterized by the above-mentioned.
- the corrosion resistant steel material for crude oil tanks of the present invention may further include one or two selected from Ca: 0.0002 to 0.005 mass% and REM: 0.0005 to 0.015 mass%. It contains seeds.
- the corrosion-resistant steel material for crude oil tank according to the present invention is characterized in that the microstructure at the position of the steel plate thickness 1 ⁇ 4 contains pearlite having an area ratio of 2 to 20%.
- the corrosion resistant steel material for crude oil tank of the present invention is characterized in that a coating film containing metal Zn or Zn compound is formed on the surface of the steel material.
- the corrosion resistant steel material for crude oil tank of the present invention is characterized in that the Zn content in the coating film is 1.0 g / m 2 or more.
- the steel material having the above component composition is heated to 1000 to 1350 ° C. and then hot-rolled at a rolling finishing temperature of 750 ° C. or higher, and 650 ° C. or lower at a cooling rate of 2 ° C./sec or higher.
- a method for producing corrosion-resistant steel for crude oil tanks that cools to a cooling stop temperature of °C or higher.
- the present invention is a crude oil tank using the above steel material.
- the present invention it is possible to provide a steel material that does not cause general corrosion or local corrosion at a low cost when used in any part of a crude oil tank such as an oil tank of a crude oil tanker or a tank for transporting or storing crude oil. Can be achieved, so it has a significant industrial effect.
- C 0.001 to 0.16 mass%
- C is an element that enhances the strength of the steel material. In the present invention, it is necessary to contain 0.001 mass% or more in order to obtain a desired strength. On the other hand, C not only deteriorates the corrosion resistance as the content increases, but addition exceeding 0.16% by mass degrades the weldability and the toughness of the welded heat affected zone. Let Therefore, C is in the range of 0.001 to 0.16 mass%. From the viewpoint of further improving the strength and toughness, the range of 0.01 to 0.15 mass% is preferable. A range of 0.05 to 0.15 mass% is more preferable.
- Si 1.5 mass% or less
- Si is an element that acts as a deoxidizing agent and increases the strength, but addition exceeding 1.5 mass% reduces the toughness of the steel. Therefore, in this invention, Si is limited to the range of 1.5 mass% or less.
- Si since Si forms an anticorrosion film in an acidic environment and contributes to an improvement in corrosion resistance, it is added in a range of 0.2 to 1.5 mass% from the viewpoint of improving the corrosion resistance in an acidic environment. The range of 0.3 to 1.5 mass% is more preferable.
- Mn 0.1 to 2.5 mass%
- Mn is an element that increases the strength of the steel material.
- Mn needs to be contained in an amount of 0.1 mass% or more in order to obtain a desired strength.
- addition exceeding 2.5 mass% reduces the toughness and weldability of the steel and promotes segregation, leading to non-uniform steel sheet composition. Therefore, Mn is in the range of 0.1 to 2.5 mass%. From the viewpoint of maintaining high strength and suppressing the formation of inclusions that deteriorate the corrosion resistance, a range of 0.5 to 1.6 mass% is preferable, and a range of 0.8 to 1.4 mass% is more preferable. preferable.
- P 0.025 mass% or less
- P is a harmful element that segregates at the grain boundary to lower the toughness of the steel and also reduces the corrosion resistance, and is desirably reduced as much as possible.
- the content exceeds 0.025 mass%, central segregation is promoted to cause non-uniform steel sheet composition and the toughness is significantly reduced. Therefore, P is 0.025 mass% or less.
- the lower limit of P is preferably about 0.003 mass%, and improves overall corrosion resistance in an acidic environment. From a viewpoint of making it, it is preferable to set it as 0.010 mass% or less. Furthermore, 0.009 mass% or less is more preferable.
- S 0.01 mass% or less
- S is a harmful element that forms MnS, which is a non-metal inclusion, and becomes a starting point of corrosion, reducing local corrosion resistance and overall corrosion resistance. It is desirable to reduce as much as possible. In particular, when the content exceeds 0.01 mass%, the local corrosion resistance and the general corrosion resistance are significantly reduced. Therefore, in the present invention, the upper limit of S is set to 0.01 mass%. From the viewpoint of further improving the corrosion resistance, 0.0020 mass% or less is desirable. However, since extreme reduction of S causes an increase in manufacturing cost, it is practically 0.0002 to 0.0020 mass%. Furthermore, 0.0009 mass% or less is more preferable.
- Al 0.005 to 0.1 mass%
- Al is an element which acts as a deoxidizing agent, and in the present invention, it is necessary to contain 0.005 mass% or more. On the other hand, if added in excess of 0.1 mass%, the toughness of the steel decreases. Therefore, Al is set in the range of 0.005 to 0.1 mass%. Preferably, it is in the range of 0.01 to 0.05 mass%. A range of 0.02 to 0.04 mass% is more preferable.
- N 0.001 to 0.008 mass% N needs to be added in an amount of 0.001 mass% or more in order to improve the toughness of the steel and the mechanical properties of the weld joint part.
- Cu 0.008 to 0.35 mass%
- Cu has the effect of suppressing the overall corrosion by forming an anticorrosion coat, and is an essential element in the present invention. However, if it is less than 0.008 mass%, the above effect cannot be obtained.
- Cu when Cu is added in combination with Sn, the overall corrosion resistance is remarkably improved.
- Cu when Cu is added in an amount exceeding 0.35 mass%, the hot workability is lowered and the manufacturability is impaired. Therefore, Cu is in the range of 0.008 to 0.35 mass%.
- the range of 0.008 to 0.15 mass% is preferable from the viewpoint of cost effectiveness. A range of 0.01 to 0.14 mass% is more preferable.
- Cr more than 0.1 mass% and less than 0.5 mass% Cr forms a protective coating (protective coating) on the surface of the steel material together with Cu, improves the overall corrosion resistance in an acidic environment, and has the effect of increasing the strength of the steel material.
- addition is an essential element.
- Cr forms an oxide layer to cover the steel surface and has the effect of reducing the overall corrosion rate.
- the Zn compound remains in the rust layer for a long time even when the zinc primer is applied, and thus greatly contributes to the improvement of the corrosion resistance, including the corrosion resistance after coating.
- the addition amount of Cu can be suppressed by the effect of improving the corrosion resistance by adding Cr, there is an effect of reducing a decrease in hot workability caused in the presence of Cu and Sn.
- Cr is added in an amount of 0.1 mass% or less.
- the content exceeds 0.5 mass%, the above effect is saturated, and the cost is increased and weldability is deteriorated. . Therefore, Cr is added in a range of more than 0.1 mass% and 0.5 mass% or less. A range of 0.11 to 0.3 mass% is more preferable. The range of 0.12 to 0.2 mass% is more preferable.
- Sn 0.005 to 0.3 mass% Sn, due to the combined effect with Cu, or when adding W as will be described later, due to the combined effect with Cu and W to form a dense rust layer to suppress the overall corrosion in an acidic environment, It has an effect of suppressing local corrosion, and is an essential element in the present invention. However, if the amount is less than 0.005 mass%, the above-described addition effect is not obtained. On the other hand, the addition exceeding 0.3 mass% causes deterioration of hot workability and toughness. Therefore, Sn is set to a range of 0.005 to 0.3 mass%. A range of 0.02 to 0.1 mass% is more preferable. A range of 0.03 to 0.09 mass% is more preferable.
- Mo 0.01 mass% or less
- Mo is generally considered to be an element having the same action as W and improving the corrosion resistance.
- the inventors have formed an insoluble salt in an acidic salt water environment, whereas Mo forms a soluble salt in an acidic salt water environment and does not exhibit a barrier effect. It was newly found that when the Mo content exceeds 0.01 mass%, the corrosion resistance in an acidic salt water environment deteriorates. Therefore, in the present invention, the Mo content is limited to 0.01 mass% or less. Preferably it is 0.008 mass% or less, More preferably, it is 0.005 mass% or less.
- the above elements are basic components of the steel material of the present invention. However, in order for the steel material of the present invention to have excellent overall corrosion resistance and local corrosion resistance, not only the above components are in the above composition range, but also the A1 defined by the following formula (1): It is necessary to contain so that a value may be 0 or less. Further preferably, the value of A1 is ⁇ 1 or less.
- A1 28 ⁇ [C] + 2000 ⁇ [P] 2 + 27000 ⁇ [S] 2 + 0.0083 ⁇ (1 / [Cu]) + 0.027 ⁇ (1 / [Cr]) + 95 ⁇ [Mo] +0.00098 ⁇ (1 / [Sn]) ⁇ 6
- [C], [P], [S], [Cu], [Cr], [Mo], and [Sn] in the above formula are the content of each element (mass%).
- the above equation (1) is an empirical equation representing an index of corrosion resistance obtained by the corrosion test conducted in the present invention and summarizing the influence of each element on the overall corrosion resistance and local corrosion resistance. It has been found that if the value exceeds 0, it is impossible to ensure one or both of general corrosion resistance and local corrosion resistance.
- the elements of the primary and secondary terms decrease in overall corrosion resistance and local corrosion resistance as the element is added.
- the element of the term which is the reciprocal indicates that the general corrosion resistance and the local corrosion resistance are improved as the element is added. That is, C and Mo are corrosion resistance decreasing elements, P and S are corrosion resistance decreasing elements that are affected by the square of the content, and Cu, Cr, and Sn are corrosion resistance improving elements.
- Ni can be added in the following range in addition to the above basic components.
- Ni is added in combination with Cu, thereby suppressing the deterioration of hot workability.
- the addition is less than 0.005 mass%, the above effect cannot be obtained.
- the addition exceeding 0.4 mass% causes an increase in cost. Therefore, Ni is preferably added in the range of 0.005 to 0.4 mass%. From the viewpoint of cost effectiveness, the range of 0.005 to 0.15 mass% is more preferable. A range of 0.005 to 0.1 mass% is more preferable. Furthermore, the range of 0.03 to 0.1 mass% is even more preferable.
- Ni is an element that reduces the corrosion resistance.
- A2 28 ⁇ [C] + 2000 ⁇ [P] 2 + 27000 ⁇ [S] 2 + 0.0083 ⁇ (1 / [Cu]) + 2 ⁇ [Ni] + 0.027 ⁇ (1 / [Cr]) + 95 ⁇ [ Mo] + 0.00098 ⁇ (1 / [Sn]) ⁇ 6 (2)
- [C], [P], [S], [Cu], [Ni], [Cr], [Mo], and [Sn] in the above formula are the content of each element (mass%). Indicates.
- the steel material of this invention can further add 1 type or 2 types chosen from Sb and W in the following range.
- Sb 0.005 to 0.3 mass%
- Sb like Sn, suppresses corrosion in an acidic environment by forming a dense rust layer due to the combined effect with Cu, or when adding W as described below, due to the combined effect with Cu and W. It can be added when it is desired to further improve this property. However, if the addition is less than 0.005 mass%, there is no effect. On the other hand, if the addition exceeds 0.3 mass%, the effect is saturated and the workability is lowered. Therefore, when Sb is added, it is preferably in the range of 0.005 to 0.3 mass%. A range of 0.02 to 0.15 mass% is more preferable. A range of 0.03 to 0.09 mass% is more preferable.
- W 0.001 to 0.5 mass%
- W is a corrosion effect of WO 4 2- ions formed in a corrosive environment, forming a barrier effect against anions such as chloride ions and forming insoluble FeWO 4. Suppresses the progression of Furthermore, there is also an effect of densifying the rust layer formed on the steel plate surface. And, W has an effect of suppressing the progress of local corrosion and general corrosion in a corrosive environment where H 2 S and Cl ⁇ exist due to these chemical and physical effects. However, if the amount is less than 0.001 mass%, a sufficient addition effect cannot be obtained. On the other hand, addition exceeding 0.5 mass% not only saturates the effect but also causes an increase in cost. Therefore, when W is added, it is preferably in the range of 0.001 to 0.5 mass%. A range of 0.02 to 0.1 mass% is more preferable. A range of 0.03 to 0.09 mass% is more preferable.
- each element when adding Sb and / or W, instead of the value of A1 or A2, each element is set so that the value of A3 defined by the following formula (3) is 0 or less. It is necessary to contain. Further, preferably, the value of A3 is ⁇ 1 or less.
- Sb and W are elements that improve the corrosion resistance.
- A3 28 ⁇ [C] + 2000 ⁇ [P] 2 + 27000 ⁇ [S] 2 + 0.0083 ⁇ (1 / [Cu]) + 2 ⁇ [Ni] + 0.027 ⁇ (1 / [Cr]) + 95 ⁇ [ Mo] + 0.00098 ⁇ (1 / [Sn]) + 0.0019 (1 / ([Sb] + [W])) ⁇ 6.5 ...
- [C], [P], [S], [Cu], [Ni], [Cr], [Mo], [Sn], [Sb] and [W] in the above formula are respectively The element content (mass%) is shown.
- Nb 0.002 to 0.1 mass%
- Nb is an element added for the purpose of improving the strength and toughness of steel. However, if it is less than 0.002 mass%, the effect is not obtained. On the other hand, if it exceeds 0.1 mass%, the effect is saturated. Therefore, when Nb is added, it is preferably in the range of 0.002 to 0.1 mass%. A range of 0.004 to 0.05 mass% is more preferable. A range of 0.005 to 0.01 mass% is more preferable.
- V 0.002 to 0.1 mass%
- V is an element added for the purpose of improving the strength of steel. However, if it is less than 0.002 mass%, there is no effect of improving the strength. On the other hand, addition exceeding 0.1 mass% causes a decrease in toughness. Therefore, when it is added, it is preferably in the range of 0.002 to 0.1 mass%. A range of 0.003 to 0.05 mass% is more preferable. A range of 0.004 to 0.01 mass% is more preferable.
- Ti 0.001 to 0.1 mass%
- Ti is an element added for the purpose of improving the strength and toughness of steel. However, if it is less than 0.001 mass%, the effect is not obtained. On the other hand, if it exceeds 0.1 mass%, the effect is saturated. Therefore, when adding, it is preferable to set it as the range of 0.001-0.1 mass%. A range of 0.005 to 0.03 mass% is more preferable. The range of 0.006 to 0.02 mass% is more preferable.
- B 0.01 mass% or less B is an element added for the purpose of improving the strength of steel, and the effect is obtained by adding 0.0003 mass% or more. However, since addition exceeding 0.01 mass% reduces toughness, when adding, it is preferable to make it 0.01 mass% or less. A range of 0.0003 to 0.002 mass% is more preferable. The range of 0.0003 to 0.0015 mass% is more preferable.
- Ca 0.0002 to 0.005 mass%
- Ca has an effect of improving ductility and toughness by morphological control of inclusions, and also has an effect of improving corrosion resistance in the paint state. Therefore, Ca is added for the purpose of improving these properties. can do. However, if the amount is less than 0.0002 mass%, the effect is not obtained. On the other hand, addition exceeding 0.005 mass% causes a decrease in toughness. Therefore, when adding, it is preferable to set it as the range of 0.0002 to 0.005 mass%. From the viewpoint of improving corrosion resistance, a range of 0.001 to 0.005 mass% is more preferable. A range of 0.001 to 0.003 mass% is more preferable.
- REM 0.0005 to 0.015 mass% REM (Rare Earth Metal) means a rare earth element having an atomic number of 57 to 71, and can be generally added using misch metal which is a mixture containing La, Ce, Pr, Nd and the like.
- This REM has the effect
- the balance other than the above components is composed of Fe and inevitable impurities.
- the steel material of the present invention does not reject the inclusion of other elements as long as the effects of the present invention are not impaired. For example, if it is O, 0.008% or less is contained. be able to.
- the microstructure of the steel material for crude oil tank of the present invention will be described.
- the microstructure at a position of 1/4 of the sheet thickness t is composed of a composite structure composed of ferrite, pearlite, and bainite transformation, and an area ratio of 2 to 2 It preferably contains 20% pearlite.
- various structure control methods are used as a method for controlling the strength of steel having the same composition. Among them, water cooling after hot rolling is one of the most used methods. It is.
- the steel material having the component composition of the present invention forms a microstructure composed of ferrite and pearlite when subjected to slow cooling after hot rolling, but when a rapid cooling treatment represented by water cooling is performed, Perlite changes to a stronger bainite structure. In particular, the higher the cooling rate and the lower the cooling stop temperature, the higher the ratio of bainite structure, and finally a two-phase structure of ferrite and bainite.
- the bainite structure is a cementite microdispersed structure, it has the property of accelerating corrosion in an acidic environment. Accordingly, the corrosion resistance can be improved by leaving a certain amount of the pearlite structure and suppressing the fine dispersion of cementite. The effect of improving the corrosion resistance by leaving the pearlite clearly appears when the pearlite area ratio is 2% or more. On the other hand, if the area ratio of the pearlite structure exceeds 20%, the toughness decreases, which is not preferable. Therefore, in order to obtain better corrosion resistance in the steel material of the present invention, the area ratio of pearlite in the microstructure is preferably controlled in the range of 2 to 20%.
- the reason why the measurement position of the microstructure is set to a position of 1/4 of the thickness of the steel material is as follows. This is because the thickness can be represented, and even if the processed surface of the steel material is exposed to a corrosive environment, the entire surface corrosion resistance can be satisfied from the surface layer of the steel material to the center of the plate thickness.
- the corrosion resistant steel material for a crude oil tank of the present invention having a microstructure generally has a strength with a yield stress of 315 MPa or more and a tensile strength of 440 MPa or more. Note that the bainite structure may not exist as long as a predetermined strength is obtained.
- the steel material of this invention can be manufactured by the same method as the conventional steel material by using the steel raw material which controlled the component composition to the range of the said invention.
- secondary refining furnaces such as converters, electric furnaces, vacuum degassing equipment, etc., in addition to C, Si, Mn, P and S, which are the main five elements
- the contents of Cu, Cr, Sn, and Mo are adjusted within the scope of the present invention, and other alloy elements are added as necessary, and a steel suitable for the present invention is melted.
- the molten steel is made into a steel slab (steel slab) by a continuous casting method or ingot-bundling rolling method, and the steel slab is reheated as it is or after being reheated and heated. Hot rolling is performed.
- a steel material having a component composition prepared in a range is heated to 1000 to 1350 ° C., and then hot-rolled at a finishing temperature of 750 ° C. or higher and 650 ° C. or lower and 450 ° C. or higher at 2 ° C./sec or higher. It is necessary to cool to the cooling stop temperature.
- Slab heating temperature 1000-1350 ° C
- the heating temperature is less than 1000 ° C.
- the deformation resistance is large and hot rolling becomes difficult.
- heating exceeding 1350 ° C. may cause generation of surface marks, increase in scale loss, and fuel basic unit.
- it is in the range of 1100 to 1300 ° C.
- Hot rolling finishing temperature 750 ° C. or higher
- the hot rolling finishing temperature needs to be 750 ° C. or higher. If the temperature is lower than 750 ° C., a waiting time until the steel material reaches a predetermined rolling temperature is generated, so that rolling efficiency is reduced, or rolling resistance is increased due to an increase in deformation resistance. This is because it becomes difficult to roll.
- Cooling rate after hot rolling 2 ° C./sec or more
- cooling stop temperature 650 ° C. or less
- the cooling rate after hot rolling needs to be cooled at 2 ° C./sec or more. This is because if it is less than 2 ° C./sec, the ferrite becomes coarse and the yield stress decreases.
- the upper limit of the cooling rate is not particularly limited, but may be about 80 ° C./sec or less obtained by normal water cooling.
- the cooling stop temperature needs to be 650 ° C. or lower and 450 ° C. or higher. This is because if it exceeds 650 ° C., the ferrite becomes coarse and the yield stress decreases, whereas if it is less than 450 ° C., the pearlite fraction becomes less than 2%.
- a coating material such as a primer containing metal Zn or a Zn compound (hereinafter collectively referred to as a “zinc primer”), thereby making it resistant. Used with improved local and general corrosion resistance. Since these steel materials are subjected to shot blasting on the surface and then coated with a zinc primer, depending on the surface condition such as the roughness of the steel plate, the base may not be completely covered. It is said that a coating thickness of a certain amount or more (for example, 15 ⁇ m or more) is necessary for complete coverage.
- the steel material for crude oil tanks of the present invention manufactured by the above method using the steel material having the above component composition is excellent in corrosion resistance (overall corrosion resistance, local corrosion resistance) even in the unpainted state. It is characterized by excellent corrosion resistance after painting.
- the steel material for crude oil tanks of the present invention is such that the coating amount of the primer containing metal Zn or Zn compound is 1.0 g / m 2 or more in terms of Zn content, thereby allowing local corrosion resistance and overall surface resistance. Corrosivity can be remarkably improved. Furthermore, if it is 2.5 g / m 2 or more, more excellent local corrosion resistance and overall corrosion resistance can be obtained.
- the upper limit thickness Is preferably 100 ⁇ m.
- the relationship between the coating thickness of the zinc primer and the Zn content on the steel surface depends on the Zn content in the zinc primer. Generally, if the average coating thickness is 15 ⁇ m or more, the steel material The entire surface can be covered, and a coating amount of 1.0 g / m 2 or more can be secured in terms of Zn content regardless of the type of zinc primer.
- the Zn content on the surface of the steel sheet is, for example, a plurality of (for example, 10) pieces of 30 mm square pieces cut out from the steel material, and all the coating film or rust layer on the surface is dissolved and recovered, and the amount of Zn contained therein Can be obtained by analyzing the above.
- Steel having the component composition shown in Table 1-1 to Table 1-4 is melted using a converter or the like, and is formed into a slab having a thickness of 200 mm by a continuous casting method. After heating these slabs to 1200 ° C., The finish rolling finish temperature is 800 ° C hot rolled to a plate thickness of 25 mm, and then cooled to 580 ° C at a cooling rate of 30 ° C / sec. 1 to 35 steel plates were produced.
- the pearlite area ratio was measured by observing the microstructure at the position of the thickness 1 ⁇ 4, and all of these steel sheets had a pearlite area ratio of 2% or more in the microstructure. I confirmed that there was.
- steel sheets having different pearlite area ratios in the microstructure were produced by changing the cooling rate and the cooling stop temperature after hot rolling.
- test piece having a length of 50 mm, a width of 50 mm and a thickness of 5 mm was taken with the position of the thickness 1/4 of each steel plate obtained as described above being tested, and shot blasting was performed on the surface. After that, it has a total of four types of surface states, that is, a test piece in an unpainted state as shot blast, and three types of test pieces in which the thickness of the zinc primer is 5-10 ⁇ m, 15-25 ⁇ m and 50-70 ⁇ m A corrosion test piece was prepared.
- the Zn content per unit area is proportional to the thickness of the zinc primer if the coating state is uniform, and generally the type of zinc primer if the thickness of the zinc primer is 15 ⁇ m. Regardless of this, 1.0 g / m 2 or more can be secured in terms of the Zn coating amount.
- test piece was subjected to a local corrosion test in which the test piece was immersed in a test solution of the test apparatus having the structure shown in FIG. 1 for one month.
- This test apparatus is composed of a double structure of a corrosion test bath 2 and a constant-temperature bath 3, and in the corrosion test bath 2, local corrosion that occurs in an actual crude oil tank bottom plate and A test solution 6 capable of causing similar local corrosion is injected.
- This test solution 6 uses a 10 mass% NaCl aqueous solution containing 5000 mass ppm of sulfate ions as a mother liquor.
- a mixed gas 4 adjusted to a concentration ratio of CO 2 : 13 vol% + O 2 : 5% volO 2 + SO 2 : 0.01 vol% + H 2 S: 0.3 vol% was introduced into the mother liquor and dissolved therein.
- the solution was used.
- the adjustment gas the balance of the mixed gas 4 (adjustable gas) was set to inert N 2 gas (inert nitrogen gas).
- the test liquid 6 is constantly stirred.
- the temperature of the test solution 6 was kept at 40 ° C. by adjusting the temperature of the water 7 put in the thermostat 3.
- the local corrosion resistance was evaluated based on the following criteria. ⁇ Evaluation of local corrosion resistance> AA: No local corrosion occurred A: Local corrosion depth of less than 0.5 mm B ⁇ : Local corrosion depth of 0.5 mm or more and less than 1 mm C ⁇ : Local corrosion depth of 1 mm or more
- the results of the local corrosion test are shown in Tables 2 and 3. From Table 2, No. 1 suitable for the present invention.
- the steel sheets according to the invention examples 1 to 21 were cases where the local corrosion resistance was all evaluated as AA ⁇ or A ⁇ regardless of whether or not the zinc primer was applied, and local corrosion occurred in the unpainted state. However, the maximum depth is suppressed to less than 0.5 mm, and it has good local corrosion resistance.
- a coating with a zinc primer of 15 ⁇ m or more that is, a coating with a uniform zinc primer and a Zn content of 1.0 g / m 2 or more is No. All of 3 to 21 were AA ⁇ , and it was confirmed that the local corrosion resistance was remarkably improved by applying the zinc primer.
- the comparative example No. which does not satisfy the conditions of the present invention.
- Steel sheets of 22 to 35 that is, those in which at least one of the contents of Cu, Cr and Sn is below the scope of the present invention, those in which the contents of P, S and Mo exceed the scope of the present invention, or the corrosion resistance indices A1 to A3
- the evaluation of local corrosion resistance is C ⁇ or B ⁇ not only when the zinc primer is not applied but also when it is applied. That is, the steel plate of the comparative example is not only inferior in local corrosion resistance in an unpainted state, but also when the zinc primer is applied, the improvement is slight.
- Table 3 shows the results of evaluating local corrosion resistance in a non-painted state in the same manner as described above, using a steel sheet in which the area ratio of pearlite in the microstructure was changed. From Table 3, it was confirmed that the local corrosion resistance tends to be improved in the microstructure steel plate containing pearlite in an area ratio of 2% or more as compared with the microstructure steel plate containing only bainite not containing pearlite.
- Example 1 No. obtained in Example 1. From the position of the plate thickness 1 ⁇ 4 of the steel plate 1 to 35, a rectangular test piece having a length of 50 mm ⁇ width of 25 mm ⁇ thickness of 4 mm was sampled and subjected to shot blasting on the surface. Non-painted test material as shot blast and test piece with zinc primer thickness (proportional to Zn content per unit area) divided into 3 levels of 5-10 ⁇ m, 15-25 ⁇ m and 50-70 ⁇ m Corrosion test pieces having a total of four types of surface states were prepared. In addition, in order to accelerate corrosion, the test piece to which the zinc primer was applied was subjected to X-shaped cutting reaching the surface of the steel material on the surface to be tested, and this was used as a simulated damaged portion. In addition, the damage of the coating film at this time was 1.0% in area ratio.
- test piece was subjected to a general corrosion test using the test apparatus shown in FIG. 2 that can simulate the corrosive environment in the crude oil tank.
- This corrosion test apparatus is composed of a corrosion test tank 12 and a temperature control plate 13, and water 16 is injected into the corrosion test tank 12 in order to maintain a saturated vapor pressure, and the temperature is maintained at 30 ° C. Yes.
- CO 2 13 vol%
- O 2 5 vol%
- SO 2 0.01 vol%
- H 2 S 0.01 vol%
- the balance is filled with a mixed gas of N 2 under saturated water vapor pressure (dew point: 30 ° C.).
- the test piece is attached below the temperature control plate installed in the upper part of the corrosion test tank, and is heated and cooled by a heater and a cooling device at 25 ° C. ⁇ 1 hour / 50 ° C. ⁇ 5 hours: 1 hour for each hour.
- the cycle (8 hours) was applied for 28 days to simulate the general corrosion caused by condensed water.
- 500 ⁇ L of an aqueous solution mixed with sodium sulfate and sodium chloride corresponding to 1000 massppm of sulfate ions and 10000 massppm of chloride ions is applied and dried. The test was conducted. In addition, after the start of the test, sulfate ions and chloride ions were supplied every week.
- the results of the overall corrosion test are shown in Tables 4 and 5. From Table 4, No. 1 suitable for the present invention.
- the steel sheets of the inventive examples 1 to 21 are all excellent in the evaluation of the overall corrosion resistance of the unpainted material as A ⁇ , and the overall corrosion resistance applied with the zinc primer is also A ⁇ . It was confirmed that the steel sheet of the invention example had good general corrosion resistance in an unpainted state, and even better general corrosion resistance by applying a zinc primer.
- the steel plate No. Nos. 22 to 35 are evaluated not only when the zinc primer is not applied, but also when applied, the evaluation of the general corrosion resistance is C ⁇ or B ⁇ . In either case, the general corrosion resistance is inferior.
- Table 5 shows a surface corrosion test in a non-painted state using the steel sheet obtained in Example 1 and having a changed pearlite area ratio in the microstructure. It shows the result of evaluating. From Table 5, it was found that the steel sheet having a pearlite area ratio of 2% or more tends to improve the overall corrosion resistance as well as the local corrosion resistance.
- the technology of the present invention is not limited to oil tanks for crude oil tankers, such as oil tanks for crude oil tankers or tanks for transporting or storing crude oil, but for other fields of steel used in similar corrosive environments. Also, it can be suitably applied, including the case where primer coating or normal coating is used in combination.
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Abstract
Description
(1)昼夜の温度差による鋼板面への結露(dew drop)と乾湿の繰り返し(alternate wetting and drying)、
(2)原油タンク内に防爆(explosion protection)用に封入されるイナートガス(inert gas)(O2約5vol%、CO2約13vol%、SO2約0.01vol%、残部N2を代表組成とするボイラ(boiler)あるいはエンジン(engine)の排ガス(exhaust gas))中のO2、CO2、SO2の結露水への溶け込み、
(3)原油から揮発するH2S等の腐食性ガスの結露水(dew condensation water)への溶け込み、
(4)原油タンクの洗浄(cleaning)に使用される海水(salt water)の残留、
などが挙げられる。これらは、実際のドック検査(dock inspection)時における調査で、強酸性(strong acidity)の結露水と、硫酸イオン(sulfate ion)および塩化物イオン(chloride ion)が検出されていることからも窺い知ることができる。
(1)塩化ナトリウム(sodium chloride)を代表とする塩類が高濃度に溶解した凝集水(brine)の存在、
(2)過剰な洗浄によるオイルコートの離脱、
(3)原油中の硫化物(sulfide)の高濃度化、
(4)原油タンク内に防爆用に封入されたイナートガス中のO2、CO2、SO2の高濃度化、
(5)微生物(microorganism)等の関与、
などの項目が挙げられているが、いずれも推定の域を出ず、明確な原因は未だ判明していない。なお、実際のドック検査時における原油タンク内の滞留水の分析では、高濃度の塩化物イオンと硫酸イオンが検出されている。
例えば、特許文献1には、質量%で、C:0.01~0.3%を含有する鋼に、適正量のSi,Mn,P,Sと、Ni:0.05~3%を添加し、さらに選択的にMo,Cu,Cr,W,Ca,Ti,Nb,V,Bを添加した全面腐食や局部腐食に対する抵抗性を改善したカーゴオイルタンク用の耐食鋼が開示されている。
なお、H2Sを含む乾湿繰り返し環境においては、Crの含有量が、0.05mass%超えると、耐全面腐食性と耐孔食性の低下が著しくなるので、Crの含有量は、0.05mass%以下とすることが、開示されている。
原油タンク内に防爆のために封入されるイナートガスには水蒸気が含まれる。そのため、航海中の昼夜の温度差でタンク内壁の鋼材表面に結露を生じる。この結露水には、イナートガス成分であるCO2(二酸化炭素)やO2(酸素),SO2(二酸化硫黄)および原油からの揮発成分であるH2S(硫化水素)等が溶け込み、硫酸イオンを含む腐食性の酸性溶液を生成する。また、原油タンクの海水洗浄によって持ち込まれる塩化物イオン(chloride ion)も考慮する必要がある。これらの成分が溶け込んだ腐食性の酸性溶液(acid solution)は、鋼板温度が上昇する過程で濃化し、鋼板表面に全面腐食を生じさせる。さらに、鋼板表面に形成した鉄さびを触媒として、H2SからS(硫黄)が析出し、鉄さびと硫黄が層状となったさび層を形成するため、鋼板表面のさび層は、脆く保護性のないものとなり、腐食が継続的に進行する。
実際の原油タンク底板で発生するお椀型の局部腐食では、底板上に滞留する溶液中に含まれるO2およびH2Sが主な支配因子として働き、具体的には、O2とH2Sが共存し、かつ、O2濃度とH2S濃度の両方がある範囲の環境下(O2濃度:2~8vol%、H2S濃度:0.1~5vol%のガスを飽和させた水溶液中)で局部腐食が生じる。つまり、低O2濃度かつ低H2S濃度の環境下では、H2Sが酸化されて固体Sが析出する。この析出した固体Sは、原油タンク底板との間で局部電池を形成し、鋼材表面に局部腐食を引き起こす。この局部腐食は、塩化物イオンおよび硫酸イオンの存在する酸性環境下ではさらに促進されて成長する。
本発明は、上記知見に基づき、さらに検討を加えてなされたものである。
A1=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])−6 ・・・(1)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Cr]、[Mo]および[Sn]は、それぞれの元素の含有量(mass%)
で定義するA1の値が0以下であることを特徴とする原油タンク用耐食鋼材である。
A2=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+2×[Ni]+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])−6 ・・・(2)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Ni]、[Cr]、[Mo]および[Sn]は、それぞれの元素の含有量(mass%)
に定義するA2の値が0以下であることを特徴とする。
A3=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+2×[Ni]+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])+0.0019×(1/([Sb]+[W]))−6.5
・・・(3)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Ni]、[Cr]、[Mo]、[Sn]、[Sb]および[W]は、それぞれの元素の含有量(mass%)
に定義するA3の値が0以下であることを特徴とする。
C:0.001~0.16mass%
Cは、鋼材の強度を高める元素であり、本発明では所望の強度を得るために、0.001mass%以上の含有を必要とする。一方、Cは、含有量の増加とともに耐食性が劣化するだけでなく、0.16mass%を超える添加は、溶接性(weldability)および溶接熱影響部(welded heat affected zone)の靭性(toughness)を劣化させる。よって、Cは0.001~0.16mass%の範囲とする。なお、強度、靭性をより向上する観点からは、0.01~0.15mass%の範囲が好ましい。0.05~0.15mass%の範囲がより好ましい。
Siは、脱酸剤(deoxidizing agent)として作用するとともに、強度を増加させる元素であるが、1.5mass%を超える添加は、鋼の靭性を低下させる。そのため、本発明では、Siは1.5mass%以下の範囲に限定する。なお、Siは、酸性環境において、防食皮膜を形成して耐食性の向上に寄与するので、酸性環境での耐食性を改善する観点からは、0.2~1.5mass%の範囲で添加するのが好ましく、0.3~1.5mass%の範囲がより好ましい。
Mnは、鋼材の強度を高める元素であり、本発明では所望の強度を得るために、0.1mass%以上の含有を必要とする。一方、2.5mass%を超える添加は、鋼の靭性および溶接性を低下させるとともに、偏析を助長して鋼板組成の不均一化を招く。よって、Mnは0.1~2.5mass%の範囲とする。なお、高強度を維持し、かつ、耐食性を劣化させる介在物の形成を抑制する観点からは、0.5~1.6mass%の範囲が好ましく、0.8~1.4mass%の範囲がより好ましい。
Pは、粒界に偏析して鋼の靭性を低下させるとともに、耐食性をも低下させる有害な元素であり、できる限り低減するのが望ましい。特に、0.025mass%を超えて含有すると、中央偏析(central segregation)を助長して鋼板組成の不均一化を招くとともに、靭性が顕著に低下するようになるため、Pは0.025mass%以下とする。なお、Pを0.003mass%未満に低減することは、製造コストの増大を招くので、Pの下限は0.003mass%程度が好ましく、また、酸性環境(acid environment)における耐全面腐食性を向上させる観点からは、0.010mass%以下とするのが好ましい。さらに、0.009mass%以下がより好ましい。
Sは、非金属介在物(non−metal inclusion)であるMnSを形成して腐食の起点になり、耐局部腐食性および耐全面腐食性を低下させる有害な元素であり、できる限り低減するのが望ましい。特に、0.01mass%を超える含有は、耐局部腐食性および耐全面腐食性の顕著な低下を招くので、本発明では、Sの上限は0.01mass%とする。なお、より耐食性を向上する観点からは、0.0020mass%以下が望ましいが、極度のSの低減は製造コストの増大を招くので、現実的には、0.0002~0.0020mass%である。さらに、0.0009mass%以下がより好ましい。
Alは、脱酸剤として作用する元素であり、本発明では0.005mass%以上含有させる必要である。一方、0.1mass%を超えて添加すると、鋼の靭性が低下する。よって、Alは0.005~0.1mass%の範囲とする。好ましくは、0.01~0.05mass%の範囲である。0.02~0.04mass%の範囲がより好ましい。
Nは、鋼の靭性向上および溶接継手部(weld joint part)の機械的特性の向上のために、0.001mass%以上の添加が必要である。しかし、0.008mass%を超える添加は、固溶Nの増加をもたらし、溶接条件によっては、継手部の靭性を著しく低下させる。よって、Nは0.001~0.008mass%の範囲とする。好ましくは0.002~0.005mass%、より好ましくは0.002~0.004mass%の範囲である。
Cuは、防食皮膜(anticorrosion coat)を形成して全面腐食を抑制する作用があり、本発明では、添加が必須の元素である。しかし、0.008mass%よりも少ないと上記効果が得られない。一方、Cuは、Snと複合添加することで、耐全面腐食性を著しく向上するが、0.35mass%を超えて添加すると、熱間加工性が低下し、製造性を害するようになる。よって、Cuは0.008~0.35mass%の範囲とする。なお、Cu添加の効果は、添加量の増加にともない飽和していくため、費用対効果の点からは、0.008~0.15mass%の範囲が好ましい。0.01~0.14mass%の範囲がより好ましい。
Crは、Cuとともに鋼材表面に保護皮膜(protective coating)を形成し、酸性環境における耐全面腐食性を向上させるほか、鋼材強度を高める作用があり、本発明では添加が必須の元素である。特に、硫酸イオンおよび塩化物イオンを含む酸性環境において、Crは酸化皮膜(oxide layer)を形成して鋼材表面を覆い、全面腐食速度を低下する効果がある。また、Crは、Cuとともに錆層を緻密化するため、ジンクプライマー塗布された状態でもZn化合物を錆層中に長く留めるので、塗装後耐食性も含めて、耐食性の向上に大きく寄与する。さらに、Cr添加による耐食性向上効果により、Cuの添加量を抑制できるので、Cu,Sn共存下で生じる熱間加工性の低下を軽減する効果がある。しかし、Crの0.1mass%以下の添加では、上記の添加効果は得られず、一方、0.5mass%を超える添加は、上記効果が飽和するとともに、コストの上昇および溶接性の劣化を招く。よって、Crは、0.1mass%超0.5mass%以下の範囲で添加する。0.11~0.3mass%の範囲がより好ましい。0.12~0.2mass%の範囲がさらに好ましい。
Snは、Cuとの複合効果により、あるいは後述のようにWを添加する場合にはCuおよびWとの複合効果により、緻密な錆層を形成して酸性環境下における全面腐食を抑制するとともに、局部腐食をも抑制する作用があり、本発明では添加が必須の元素である。しかし、0.005mass%未満では、上記の添加効果がなく、一方、0.3mass%を超える添加は、熱間加工性および靭性の劣化を招く。よって、Snは、0.005~0.3mass%の範囲とする。0.02~0.1mass%の範囲がより好ましい。0.03~0.09mass%の範囲がさらに好ましい。
Moは、一般的にWと同様の作用を有し、耐食性を向上させる元素と考えられている。しかし、発明者らは、Wは酸性塩水環境下で不溶性の塩を形成するのに対して、Moは酸性塩水環境下では溶解性のある塩を形成し、バリア効果を発揮せず、特に、Mo含有量が0.01mass%を超えて多くなると、却って酸性塩水環境における耐食性が劣化することを新規に見出した。そこで、本発明では、Moの含有量を0.01mass%以下に制限する。好ましくは0.008mass%以下、より好ましくは0.005mass%以下である。
記
A1=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])−6 ・・・(1)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Cr]、[Mo]および[Sn]は、それぞれの元素の含有量(mass%)
上記(1)式は、本発明において行った腐食試験において得られた、耐全面腐食性および耐局部腐食性に及ぼす各元素の影響を纏めた耐食性の指標を表す経験式であり、上記A1の値が0を超えると、耐全面腐食性および耐局部腐食性のいずれか一方または両方を確保することができなくなることがわかっている。なお、上記(1)式では、各元素の耐食性に及ぼす影響について、1次および2次の項の元素は、その元素を添加するほど耐全面腐食性および耐局部腐食性が低下することを、一方、逆数となっている項の元素は、添加するほど耐全面腐食性および耐局部腐食性が向上することを示している。つまり、CおよびMoは耐食性低下元素、PおよびSは含有量の2乗で影響する耐食性低下元素、Cu,CrおよびSnは耐食性向上元素である。
Ni:0.005~0.4mass%
Niは、Cuと複合して添加することにより、熱間加工性の劣化を抑制する働きがある。しかし、0.005mass%未満の添加では上記効果が得られず、一方、0.4mass%を超える添加は、コストの上昇を招く。よって、Niは0.005~0.4mass%の範囲で添加するのが好ましい。なお、費用対効果の観点からは、0.005~0.15mass%の範囲がより好ましい。0.005~0.1mass%の範囲がより好ましい。さらに、0.03~0.1mass%の範囲であれば、より一層好ましい。
ここで、(2)式からわかるように、Niは、耐食性を低下する元素である。
記
A2=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+2×[Ni]+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])−6 ・・・(2)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Ni]、[Cr]、[Mo]および[Sn]は、それぞれの元素の含有量(mass%)を示す。
Sb:0.005~0.3mass%
Sbは、Snと同様に、Cuとの複合効果により、あるいは後述のようにWを添加する場合にはCuおよびWとの複合効果により、緻密な錆層を形成して酸性環境における腐食を抑制する作用があり、本特性をより向上させたい場合に添加することができる。しかし、0.005mass%未満の添加では効果がなく、一方、0.3mass%を超える添加では、効果が飽和するととともに、加工性が低下するようになる。よって、Sbを添加する場合は、0.005~0.3mass%の範囲とするのが好ましい。0.02~0.15mass%の範囲がより好ましい。0.03~0.09mass%の範囲がさらに好ましい。
Wは、腐食環境で形成されるWO4 2−イオンが、塩化物イオン等の陰イオン(anion)に対するバリア効果(barrier effect)を発揮するとともに、不溶性(insolubility)のFeWO4を形成して腐食の進行を抑制する。さらに、鋼板表面に形成される錆層を緻密化する効果もある。そして、Wは、これらの化学的、物理的な効果によって、H2SおよびCl−が存在する腐食環境における局部腐食および全面腐食の進行を抑制する効果がある。しかし、0.001mass%よりも少ないと十分な添加効果が得られず、一方、0.5mass%を超える添加は、その効果が飽和するだけでなく、コストの上昇を招く。よって、Wを添加する場合には、0.001~0.5mass%の範囲とするのが好ましい。0.02~0.1mass%の範囲がより好ましい。0.03~0.09mass%の範囲がさらに好ましい。
ここで、(3)式からわかるように、SbおよびWは、耐食性を向上する元素である。
記
A3=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+2×[Ni]+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])+0.0019(1/([Sb]+[W]))−6.5
・・・(3)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Ni]、[Cr]、[Mo]、[Sn]、[Sb]および[W]は、それぞれの元素の含有量(mass%)を示す。
Nb:0.002~0.1mass%
Nbは、鋼の強度および靭性向上を目的に添加する元素である。しかし、0.002mass%未満ではその効果がなく、一方、0.1mass%を超えると、効果が飽和してしまう。よって、Nbを添加する場合は、0.002~0.1mass%の範囲とするのが好ましい。0.004~0.05mass%の範囲がより好ましい。0.005~0.01mass%の範囲がさらに好ましい。
Vは、鋼の強度向上を目的に添加する元素である。しかし、0.002mass%未満では強度向上効果がなく、一方、0.1mass%を超える添加は、靭性の低下を招く。よって、添加する場合は、0.002~0.1mass%の範囲とするのが好ましい。0.003~0.05mass%の範囲がより好ましい。0.004~0.01mass%の範囲がさらに好ましい。
Tiは、鋼の強度および靭性向上を目的に添加する元素である。しかし、0.001mass%未満ではその効果がなく、一方、0.1mass%を超えると効果が飽和してしまう。よって、添加する場合は、0.001~0.1mass%の範囲とするのが好ましい。0.005~0.03mass%の範囲がより好ましい。0.006~0.02mass%の範囲がさらに好ましい。
Bは、鋼の強度向上を目的に添加する元素であり、その効果は、0.0003mass%以上の添加によって得られる。しかし、0.01mass%を超える添加は、靭性を低下させるため、添加する場合は、0.01mass%以下にするのが好ましい。0.0003~0.002mass%の範囲がより好ましい。0.0003~0.0015mass%の範囲がさらに好ましい。
Ca:0.0002~0.005mass%
Caは、介在物(inclusion)の形態制御(morphological control)によって延性(ductility)および靭性を向上させる効果があるとともに、塗装状態における耐食性を向上する効果があるので、これらの特性向上を目的として添加することができる。しかし、0.0002mass%未満では、その効果がなく、一方、0.005mass%を超える添加は、靭性の低下を招く。よって、添加する場合には、0.0002~0.005mass%の範囲とするのが好ましい。なお、耐食性向上の観点からは、0.001~0.005mass%の範囲がより好ましい。0.001~0.003mass%の範囲がさらに好ましい。
REM(Rare Earth Metal)は、原子番号が57~71までの希土類元素を意味し、一般にはLa,Ce,Pr,Ndなどを含む混合物であるミッシュメタルを用いて添加することができる。このREMは、介在物の形態を制御し、延性および靭性を向上させる作用を有する。しかし、0.0005mass%未満では、その効果がなく、一方、0.015mass%を超える添加は、靭性が低下させる。よって、添加する場合は、0.0005~0.015mass%の範囲とするのが好ましい。なお、耐食性を向上させる観点からは、0.005~0.015mass%の範囲がより好ましい。0.005~0.01mass%の範囲がさらに好ましい。
本発明の鋼材は、板厚tの1/4の位置におけるミクロ組織が、フェライト(ferrite)、パーライト(pearlite)およびベイナイト変態(bainite transformation)からなる複合組織からなり、かつ、面積率で2~20%のパーライトを含むものであることが好ましい。
一般に、同じ成分組成を有する鋼の強度を制御する方法として、各種の組織制御方法が用いられているが、中でも熱間圧延後の水冷(water cooling)は、最も用いられている方法の一つである。本発明の成分組成を有する鋼材は、熱間圧延後、徐冷(slow cooling)すると、フェライトとパーライトからなるミクロ組織(microstructure)を形成するが、水冷に代表される急冷処理を行うと、上記パーライトが、より強度の高いベイナイト組織に変化する。特に、冷却速度が大きくなるほど、また、冷却停止温度(cooling stop temperature)が低くなるほど、ベイナイト組織の比率は高まり、最終的にはフェライトとベイナイトの2相組織となる。
本発明の鋼材は、成分組成を上記本発明の範囲に制御した鋼素材を用いることにより、従来の鋼材と同様の方法で製造することができる。例えば、転炉(steel converter)や電気炉(electric furnace)、真空脱ガス装置(vacuum degassing equipment)等の2次精錬炉等で、主要5元素であるC,Si,Mn,P,Sの他に、Cu,Cr,SnおよびMoの含有量を本発明の範囲に調節するとともに、必要に応じてその他の合金元素を添加し、本発明に適合する鋼を溶製する。その後、上記溶鋼を、連続鋳造法あるいは造塊−分塊圧延法等で、鋼スラブ(steel slab)(鋼片)とし、その鋼片を、そのままあるいは冷却後、再加熱(reheat)して熱間圧延を行う。
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(scale loss)や燃料原単位(fuel basic unit)が増加したりする。好ましくは、1100~1300℃の範囲である。
熱間圧延の仕上温度は、750℃以上とする必要がある。750℃未満では、鋼材が所定の圧延温度に達するまでの待ち時間が発生するため圧延能率(rolling efficiency)が低下したり、変形抵抗(deformation resistance)の増大により圧延荷重(rolling force)が増加して圧延することが困難となったりするからである。
熱間圧延後の冷却速度(cooling rate)は、2℃/sec以上で冷却する必要がある。2℃/sec未満では、フェライトが粗大化し、降伏応力が低下するためである。一方、冷却速度の上限は、特に制限はないが、通常の水冷で得られる80℃/sec程度以下であればよい。
また、冷却停止温度は、650℃以下、450℃以上とする必要がある。650℃を超えると、フェライトが粗大化し、降伏応力が低下するからであり、一方、450℃未満ではパーライトの分率が2%未満となってしまうからである。
この点、上記の成分組成を有する鋼素材を用いて上記の方法で製造された本発明の原油タンク用鋼材は、無塗装の状態においても耐食性(耐全面腐食性、耐局部腐食性)に優れているのみならず、塗装後の耐食性にも優れているところに特徴がある。特に、本発明の原油タンク用鋼材は、金属ZnあるいはZn化合物を含むプライマーの塗布量を、Zn含有量に換算して1.0g/m2以上とすることにより、耐局部腐食性および耐全面腐食性を格段に向上することができる。さらに、2.5g/m2以上とすれば、より優れた耐局部腐食性および耐全面腐食性を得ることができる。なお、耐局部腐食性および耐全面腐食性の観点からは、ジンクプライマー塗布量の上限は設けないが、ジンクプライマーの塗膜が厚くなると、切断性や溶接性が低下するので、上限の厚さは100μmとするのが好ましい。
なお、鋼板表面のZn含有量は、例えば、鋼材から30mm角の小片を複数個(例えば、10個)切り出し、その表面の塗膜あるいはさび層をすべて溶解回収し、その中に含まれるZn量を分析することにより求めることができる。
なお、これらの鋼板については、板厚1/4の位置におけるミクロ組織を観察してパーライトの面積率を測定し、これらの鋼板の全てが、ミクロ組織中におけるパーライトの面積率が2%以上であることを確認した。
また、表1のNo.1および8の鋼については、熱間圧延後の冷却速度および冷却停止温度を変化させることによって、ミクロ組織中のパーライトの面積率が異なる鋼板を製造した。
この母液にCO2:13vol%+O2:5%volO2+SO2:0.01vol%+H2S:0.3vol%の濃度比に調整した混合ガス(mixed gas)4を導入して溶け込ませた溶液を使用した。なお、上記混合ガス4の残部である調整ガス(adjustable gas)は、不活性のN2ガス(inert nitrogen gas)とした。上記試験装置では、混合ガス4が連続して供給されるため、試験液(test liquid)6は常に撹拌されている。また、試験液6の温度は、恒温槽3に入れた水7の温度を調整することにより、40℃に保持した。
<耐局部腐食性の評価>
AA◎:局部腐食の発生なし
A○:局部腐食の深さが0.5mm未満
B△:局部腐食の深さ0.5mm以上1mm未満
C×:局部腐食の深さ1mm以上
一方、本発明の条件を満たさない比較例のNo.22~35の鋼板、すなわち、Cu,Cr,Snの含有量の少なくとも一つが本発明範囲を下回るもの、P,S,Moの含有量が本発明範囲を超えるもの、または耐食性の指標A1~A3の値のいずれかが0を超える鋼板は、ジンクプライマーを塗布していない場合のみならず、塗布している場合においても、耐局部腐食性の評価はC×またはB△である。すなわち、比較例の鋼板は、無塗装の状態で、耐局部腐食性が劣るだけでなく、ジンクプライマーを塗布した場合でも、その向上はわずかである。
また、表3は、ミクロ組織中のパーライトの面積率を変化させた鋼板を用いて、上記と同様にして、無塗装状態における耐局部腐食性を評価した結果を示したものである。表3から、パーライトを含まないベイナイトのみからなるミクロ組織の鋼板に比べ、パーライトを面積率で2%以上含むミクロ組織の鋼板では、耐局部腐食性が向上する傾向にあることが確認された。
<無塗装材の耐全面腐食性の評価>
A○:腐食速度0.2mm/年未満
B△:腐食速度0.2mm/年以上0.8mm/年未満
C×:腐食速度0.8mm/年以上
また、プライマー塗布材については、各試験片の表面および塗膜下に進行した錆の面積率を測定し、以下の基準で耐全面腐食性を評価した。
<プライマー塗布材の耐全面腐食性の評価>
A○:錆面積率25%未満
B△:錆面積率25%以上50%未満
C×:錆面積率50%%以上
一方、比較例の鋼板No.22~35は、ジンクプライマーを塗布していない場合のみならず、塗布している場合においても、耐全面腐食性の評価がC×またはB△であり、いずれの場合も耐全面腐食性が劣っていることがわかる。
また、表5は、実施例1において得た、ミクロ組織中のパーライトの面積率を変化させた鋼板を用いて、無塗装状態における全面腐食試験を行い、上記と同様の基準で耐全面腐食性を評価した結果を示したものである。表5から、パーライトの面積率が2%以上の鋼板では、耐局部腐食性と同様、耐全面腐食性も向上する傾向があることがわかった。
2、12:腐食試験槽
3:恒温槽(constant−temperature bath)
4、14:導入ガス
5、15:排出ガス
6、16:試験液(test liquid)
7:水
13:温度制御プレート
Claims (10)
- C:0.001~0.16mass%、Si:1.5mass%以下、Mn:0.1~2.5mass%、P:0.025mass%以下、S:0.01mass%以下、Al:0.005~0.1mass%、N:0.001~0.008mass%、Cu:0.008~0.35mass%、Cr:0.1mass%超0.5mass%以下、Sn:0.005~0.3mass%を含有し、Mo:0.01mass%以下であり、残部がFeおよび不可避的不純物からなり、下記(1)式で定義するA1の値が0以下である原油タンク用耐食鋼材。
記
A1=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])−6 ・・・(1)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Cr]、[Mo]および[Sn]は、それぞれの元素の含有量(mass%) - 上記成分組成に加えてさらに、Ni:0.005~0.4mass%を含有し、下記(2)式に定義するA2の値が0以下である請求項1に記載の原油タンク用耐食鋼材。
記
A2=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+2×[Ni]+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])−6 ・・・(2)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Ni]、[Cr]、[Mo]および[Sn]は、それぞれの元素の含有量(mass%) - 上記成分組成に加えてさらに、W:0.001~0.5mass%およびSb:0.005~0.3mass%のうちから選ばれる1種または2種を含有し、下記(3)式に定義するA3の値が0以下である請求項1または2に記載の原油タンク用耐食鋼材。
記
A3=28×[C]+2000×[P]2+27000×[S]2+0.0083×(1/[Cu])+2×[Ni]+0.027×(1/[Cr])+95×[Mo]+0.00098×(1/[Sn])+0.0019×(1/([Sb]+[W]))−6.5
・・・(3)
ここで、上記式中の[C]、[P]、[S]、[Cu]、[Ni]、[Cr]、[Mo]、[Sn]、[Sb]および[W]は、それぞれの元素の含有量(mass%) - 上記成分組成に加えてさらに、Nb:0.002~0.1mass%、V:0.002~0.1mass%、Ti:0.001~0.1mass%およびB:0.01mass%以下のうちから選ばれる1種または2種以上を含有する請求項1~3のいずれか1項に記載の原油タンク用耐食鋼材。
- 上記成分組成に加えてさらに、Ca:0.0002~0.005mass%およびREM:0.0005~0.015mass%のうちから選ばれる1種または2種を含有する請求項1~4のいずれか1項に記載の原油タンク用耐食鋼材。
- 鋼材の板厚1/4の位置におけるミクロ組織が、面積率で2~20%のパーライトを含む請求項1~5のいずれか1項に記載の原油タンク用耐食鋼材。
- 鋼材の表面に、金属ZnあるいはZn化合物を含む塗膜が形成されてなる請求項1~6のいずれか1項に記載の原油タンク用耐食鋼材。
- 塗膜中におけるZnの含有量が1.0g/m2以上である請求項7に記載の原油タンク用耐食鋼材。
- 請求項1~5のいずれか1項に記載の成分組成を有する鋼素材を1000~1350℃に加熱後、圧延仕上温度を750℃以上として熱間圧延し、2℃/sec以上の冷却速度で650℃以下、450℃以上の冷却停止温度まで冷却する原油タンク用耐食鋼材の製造方法。
- 請求項1~8のいずれかに記載の鋼材を用いたことを特徴とする原油タンク。
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Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001214236A (ja) * | 2000-01-31 | 2001-08-07 | Nippon Steel Corp | 原油および重油貯蔵庫用耐食鋼 |
JP2003082435A (ja) | 2001-07-04 | 2003-03-19 | Sumitomo Metal Ind Ltd | カーゴオイルタンク用鋼材 |
JP2004204344A (ja) | 2002-06-19 | 2004-07-22 | Nippon Steel Corp | 原油油槽用鋼およびその製造方法、原油油槽およびその防食方法 |
JP2005325439A (ja) | 2004-04-14 | 2005-11-24 | Sumitomo Metal Ind Ltd | カーゴオイルタンク用鋼材 |
JP2007270196A (ja) | 2006-03-30 | 2007-10-18 | Sumitomo Metal Ind Ltd | カーゴオイルタンク用鋼材 |
JP2007291494A (ja) * | 2006-03-30 | 2007-11-08 | Jfe Steel Kk | 原油タンク用耐食鋼材および原油タンク |
JP2008274379A (ja) * | 2007-05-02 | 2008-11-13 | Kobe Steel Ltd | 耐ピット性に優れた鋼板およびその製造方法 |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR101023634B1 (ko) * | 2006-03-30 | 2011-03-22 | 제이에프이 스틸 가부시키가이샤 | 원유 저장 탱크용 내식 강재 및 원유 저장 탱크 |
JP4868916B2 (ja) * | 2006-04-04 | 2012-02-01 | 株式会社神戸製鋼所 | 耐食性に優れた船舶用鋼材 |
JP5130828B2 (ja) * | 2007-08-22 | 2013-01-30 | Jfeスチール株式会社 | 高強度船舶用耐食鋼材およびその製造方法 |
JP4502075B1 (ja) * | 2008-12-24 | 2010-07-14 | Jfeスチール株式会社 | 原油タンカー用耐食鋼材 |
-
2010
- 2010-01-28 KR KR1020117015436A patent/KR20110089205A/ko active Application Filing
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- 2010-01-29 JP JP2010018274A patent/JP4640529B2/ja active Active
- 2010-01-29 TW TW99102654A patent/TWI410503B/zh active
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2001214236A (ja) * | 2000-01-31 | 2001-08-07 | Nippon Steel Corp | 原油および重油貯蔵庫用耐食鋼 |
JP2003082435A (ja) | 2001-07-04 | 2003-03-19 | Sumitomo Metal Ind Ltd | カーゴオイルタンク用鋼材 |
JP2004204344A (ja) | 2002-06-19 | 2004-07-22 | Nippon Steel Corp | 原油油槽用鋼およびその製造方法、原油油槽およびその防食方法 |
JP2005325439A (ja) | 2004-04-14 | 2005-11-24 | Sumitomo Metal Ind Ltd | カーゴオイルタンク用鋼材 |
JP2007270196A (ja) | 2006-03-30 | 2007-10-18 | Sumitomo Metal Ind Ltd | カーゴオイルタンク用鋼材 |
JP2007291494A (ja) * | 2006-03-30 | 2007-11-08 | Jfe Steel Kk | 原油タンク用耐食鋼材および原油タンク |
JP2008274379A (ja) * | 2007-05-02 | 2008-11-13 | Kobe Steel Ltd | 耐ピット性に優れた鋼板およびその製造方法 |
Non-Patent Citations (1)
Title |
---|
See also references of EP2395120A4 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN115558856A (zh) * | 2022-09-30 | 2023-01-03 | 马鞍山钢铁股份有限公司 | 一种耐微生物和二氧化碳腐蚀的管线钢及其制备方法 |
CN115558856B (zh) * | 2022-09-30 | 2023-11-03 | 马鞍山钢铁股份有限公司 | 一种耐微生物和二氧化碳腐蚀的管线钢及其制备方法 |
CN115976400A (zh) * | 2022-10-09 | 2023-04-18 | 燕山大学 | 一种耐腐蚀钢及其制备方法和应用 |
CN115976400B (zh) * | 2022-10-09 | 2024-04-26 | 燕山大学 | 一种耐腐蚀钢及其制备方法和应用 |
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