WO2018181392A1 - TÔLE D'ACIER REVÊTUE D'Al PAR IMMERSION À CHAUD ET SON PROCÉDÉ DE PRODUCTION - Google Patents

TÔLE D'ACIER REVÊTUE D'Al PAR IMMERSION À CHAUD ET SON PROCÉDÉ DE PRODUCTION Download PDF

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WO2018181392A1
WO2018181392A1 PCT/JP2018/012570 JP2018012570W WO2018181392A1 WO 2018181392 A1 WO2018181392 A1 WO 2018181392A1 JP 2018012570 W JP2018012570 W JP 2018012570W WO 2018181392 A1 WO2018181392 A1 WO 2018181392A1
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Prior art keywords
steel sheet
plating
mass
plated steel
hot
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PCT/JP2018/012570
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English (en)
Japanese (ja)
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林太 佐藤
俊佑 山本
安藤　聡
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Ｊｆｅスチール株式会社
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Priority claimed from JP2018028208A external-priority patent/JP6812996B2/ja
Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to CN201880014986.4A priority Critical patent/CN110352261B/zh
Priority to US16/489,848 priority patent/US10822685B2/en
Priority to EP18776826.2A priority patent/EP3604604A4/fr
Priority to MX2019011384A priority patent/MX2019011384A/es
Publication of WO2018181392A1 publication Critical patent/WO2018181392A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/06—Alloys based on aluminium with magnesium as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/12—Aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/261—After-treatment in a gas atmosphere, e.g. inert or reducing atmosphere
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/26—After-treatment
    • C23C2/28—Thermal after-treatment, e.g. treatment in oil bath
    • C23C2/29—Cooling or quenching

Definitions

  • the present invention relates to a hot-dip Al-based plated steel sheet having excellent post-painting corrosion resistance and post-processing corrosion resistance, and a method for producing the same.
  • Al-based plated steel sheets are widely used in the muffler materials for automobiles and the building materials field.
  • corrosion products stabilize and exhibit excellent corrosion resistance in environments with low chloride ion concentrations or in corrosive environments under dry conditions.
  • sufficient corrosion resistance cannot be exhibited in an environment where the object is exposed to the object for a long time. This is because, when exposed to chloride for a long time in a wet state, the elution rate of the plating becomes extremely fast and the base steel sheet is easily corroded.
  • an Al-based plated steel sheet is used after coating, there is a problem in that since the bottom of the coating film becomes an alkaline atmosphere, the corrosion rate of Al increases and blistering of the coating film is caused.
  • Patent Document 1 has an intermetallic compound coating layer containing Al, Fe, Si and having a thickness of 5 ⁇ m or less on the surface of a steel plate, and a weight on the surface of the intermetallic compound coating layer.
  • a hot dip galvanized steel sheet having a coating layer composed of Si: 2 to 13%, Mg: more than 3% to 15%, and the balance being substantially Al is disclosed.
  • Patent Document 2 includes a molten Al-Mg-Si plating layer containing Mg: 3 to 10% and Si: 1 to 15% by weight, with the balance being Al and inevitable impurities.
  • High corrosion resistance having a metal structure in which the plated layer is composed of at least “Al phase” and “Mg 2 Si phase” and the major axis of “Mg 2 Si phase” is 10 ⁇ m or less.
  • a plated steel sheet is disclosed.
  • Patent Document 3 contains Mg: 6 to 10% by mass, Si: 3 to 7% by mass, Fe: 0.2 to 2% by mass, and Mn: 0.02 to 2% by mass on the surface of the steel material, and the balance is A plating layer comprising Al and inevitable impurities, the plating layer having an ⁇ Al-Mg 2 Si- (Al-Fe-Si-Mn) pseudo-ternary eutectic structure, and a pseudo-ternary in the plating layer
  • An Al-based plated steel material having an eutectic structure area ratio of 30% or more is disclosed.
  • JP 2000-239820 A Japanese Patent No. 4199404 Japanese Patent No. 5430022
  • Patent Document 1 has a problem in that an Al 3 Mg 2 phase is precipitated in the plating layer, and local dissolution of the plating layer starts from this phase.
  • Patent Document 2 has a problem that a long needle-like or plate-like Al—Fe compound is deposited in the plating layer, and the local dissolution of the plating layer proceeds using this as a local cathode. It was.
  • the technique of Patent Document 3 as a result of the Al—Fe compound being incorporated into the eutectic structure by the addition of Mn, it is possible to further improve the corrosion resistance including prevention of local deterioration of the corrosion resistance.
  • the galvanic pair is formed with a more noble part of the potential of the underlying steel sheet where the coating layer is exposed to alkali and low oxygen environment and the plating layer is exposed by wrinkles, etc. To do.
  • the base steel plate is sacrificial and anticorrosive, but the corrosion rate of the plating layer is extremely increased, and blistering may occur. Therefore, the corrosion resistance after the coating film is provided (hereinafter referred to as “corrosion resistance after coating”). ) was desired to be further improved.
  • an alloy layer (interface alloy layer) mainly composed of Al and Fe is usually formed at the interface between the plating layer and the base steel sheet.
  • This interfacial alloy layer is harder than the plating layer that is the upper layer, and becomes the starting point of cracks during processing, leading to a decrease in workability, and the underlying steel sheet is exposed from the generated crack part. , “Corrosion resistance after processing”). Therefore, in addition to the above-described demand for improving post-coating corrosion resistance, development of a molten Al-based plated steel sheet that has been further improved in post-processing corrosion resistance has been desired.
  • An object of the present invention is to provide a molten Al-based plated steel sheet having excellent post-coating corrosion resistance and post-processing corrosion resistance and a method for producing the molten Al-based plated steel sheet.
  • Mg 2 Si which is located near the plating surface with a large particle size, dissolves almost simultaneously with the dissolution of the ⁇ -Al phase that occurs from the plating surface in a corrosive environment, and Mg and Si are concentrated. Producing corrosive corrosion products.
  • this corrosion product has the effect of suppressing the corrosion of plating, it is estimated that the effect of improving the corrosion resistance after coating can be obtained.
  • the inventors of the present invention have further conducted diligent research and found that Mg 2 Si having a large particle diameter (major axis exceeding 5 ⁇ m) can be formed during plating by containing a required amount of Mg and Si. Furthermore, the present inventors can suppress the thickness of the interface alloy layer by including a required amount of Mn in the interface alloy layer existing at the interface between the plating layer and the base steel sheet, and can reduce the thickness of the interface alloy. It has also been found that, as a result of the layer composition being modified to be different from the conventional one, it is possible to improve workability and to realize excellent post-processing corrosion resistance.
  • a molten Al-based plated steel sheet comprising a plating film comprising a plating layer and an interface alloy layer present at the interface between the plating layer and the base steel sheet,
  • Equation (1) MIN ⁇ Si% ⁇ ([Mg 2 Si] mol / [Si] mol), Mg% ⁇ ([Mg 2 Si] mol / (2 ⁇ [Mg] mol)) ⁇ / Al%> 0.13 M%: concentration by mass of element M, [M] mol : molar mass of element M, MIN (a, b): smaller value of a or b
  • the molten Al-based plated steel sheet of the present invention has a plating film (hereinafter also simply referred to as “plating”) comprising a plating layer and an interface alloy layer present at the interface between the plating layer and the base steel sheet. It is a hot-dip Al-based plated steel sheet.
  • the plated layer and the interface alloy layer can be observed by using a scanning electron microscope or the like for the cross section of the polished and / or etched molten Al-based plated steel sheet.
  • There are several types of methods for polishing and etching the cross section but there is no particular limitation as long as it is a method generally used for observing the cross section of the plated steel sheet.
  • the observation conditions with a scanning electron microscope are, for example, an acceleration voltage of 15 kV and a magnification of 1000 times or more in a reflected electron image, the plated layer and the interface alloy layer can be clearly observed.
  • the interface alloy layer contains Mn
  • the plating layer has Mg 2 Si having a major axis of 5 ⁇ m or more.
  • the interfacial alloy layer contains Mn
  • the potential of the interfacial alloy layer is reduced, and as a result of approaching the potential of the plating layer, dissolution of the plating layer due to different metal contact corrosion is alleviated, and post-coating corrosion resistance can be improved.
  • the thickness of the interface alloy layer can be suppressed, so that the workability can also be improved.
  • the base steel sheet is exposed by forming large-diameter Mg 2 Si having a major axis of 5 ⁇ m (hereinafter sometimes referred to as “aggregated Mg 2 Si grains”) in the plating layer. Corrosion resistance after coating can be greatly improved.
  • the effect of improving the post-coating corrosion resistance of the massive Mg 2 Si particles contained in the plating layer is particularly effective when the particle size is large, specifically, when the major axis is large Mg 2 Si exceeding 5 ⁇ m. Therefore, in the present invention, the major axis of Mg 2 Si in the plating layer exceeds 5 ⁇ m, preferably 10 ⁇ m or more, and more preferably 15 ⁇ m or more.
  • major axis of Mg 2 Si when using a scanning electron microscope to observe Mg 2 Si in the cross section of the plating layer, out of all Mg 2 Si present in the observation field, It is the diameter of Mg 2 Si with the longest diameter.
  • “having Mg 2 Si with a major axis exceeding 5 ⁇ m” means which observation field of view when a range of 1 mm in the plate width direction is observed with a scanning electron microscope in the plate thickness direction cross section of the plating layer. In the inside, it means a state in which one or more of the major axis exceeds 5 ⁇ m.
  • any cross section of the plating (however, excluding the interface alloy layer) was randomly observed in the molten Al-based plated steel sheet of the present invention. Even in this case, the condition can be satisfied.
  • the number of Mg 2 Si having a major axis exceeding 5 ⁇ m is preferably 5 or more.
  • the coating swells when wrinkles reaching the base steel plate occur It can be said that there is a sufficient amount of Mg 2 Si to suppress the above.
  • Mg 2 Si which is exposed to certain When flaw portion is 4 or less of the Mg 2 Si might not exert sufficient effect insufficient.
  • the area ratio of Mg 2 Si having a major axis exceeding 5 ⁇ m is preferably 2% or more, and 3% or more. More preferably, it is more preferably 5% or more.
  • Mg 2 Si having a large particle size suppresses selective corrosion of the interdendrite and contributes to improvement of corrosion resistance after coating. Therefore, by setting the area ratio of Mg 2 Si having a major axis exceeding 5 ⁇ m to 2% or more, better post-coating corrosion resistance can be realized.
  • the upper limit of the area ratio of Mg 2 Si is preferably about 10%.
  • the area ratio of Mg 2 Si in the present invention is, for example, a portion where a cross section of a plating film of an Al-based plated steel sheet is mapped by SEM-EDX, and Mg and Si are detected in a single field of view (A method of deriving the area ratio (%) by dividing the area of the Mg 2 Si area by the area of the plating (observation field of view) by image processing is used, but the area ratio of the area where Mg 2 Si exists is The method is not particularly limited as long as it can be grasped.
  • Mg 2 Si having a major axis of 5 ⁇ m or more formed in the plating layer preferably has a closest distance from the plating layer surface of 0.5 ⁇ m or more.
  • Mg 2 Si having a major axis of 5 ⁇ m or more and the surface of the plating layer the closest distance between Mg 2 Si having a major axis of 5 ⁇ m or more and the surface of the plating layer, the cross section of the molten Al-based plated steel sheet was observed using a scanning electron microscope, and the major axis in the observation field was 5 ⁇ m.
  • the distance between the Mg 2 Si and the plating layer surface closest to the above is the distance.
  • the closest distance between Mg 2 Si having a major axis of 5 ⁇ m or more and the plating layer surface is 0.5 ⁇ m or more, regardless of which part of the plating layer is measured.
  • the interface alloy layer of the hot-dip Al-based plated steel sheet of the present invention contains Mn as described above, and the content is preferably 5 to 30% by mass. This is because more excellent post-painting corrosion resistance and post-processing corrosion resistance can be realized.
  • the interface alloy layer further contains Al, Fe, and Si, and the concentrations thereof are Al: 30 to 90 mass%, Fe: 5 to 70 mass%, and Si: 0 to 10 mass%, respectively. Preferably there is.
  • the interfacial alloy layer further contains Al, Fe, and Si in the above concentration range, thereby including Fe 2 Al 5 , Fe 4 Al 13, and ⁇ -Al (Fe, Mn) Si as crystal components.
  • Fe 2 Al 5 , Fe 4 Al 13 and ⁇ -Al (Fe, Mn) Si have a three-layer structure ((base steel plate) / Fe 2 Al 5 / Fe 4 Al 13 / ⁇ -Al (Fe, Mn) Si / (plating layer) structure) is formed, and the most basic ⁇ -Al (Fe, Mn) Si is located immediately below the plating layer.
  • the galvanic corrosion of the plating layer can be slowed down, and excellent post-coating corrosion resistance and post-processing corrosion resistance can be realized.
  • FIG. 1 shows an example of an SEM image and a SEM-EDX profile of the cross section of the plating film for a hot-dip Al-based plated steel sheet according to an embodiment of the present invention.
  • the plating film of the Al-based plated steel sheet has a Mg 2 Si phase having a major axis of 5 ⁇ m or more, and Mn is contained in the interface alloy layer. It can also be seen that Mn is not substantially present in the plating layer and is localized in the interface alloy layer.
  • the hot-dip Al-based plated steel sheet of the present invention contains Mg: 6 to 15% by mass, Si: more than 7% by mass and 20% by mass or less, and Mn: more than 0.5% by mass and 2.5% by mass or less in the plating equipment.
  • the said plating layer and the said interface alloy layer can be formed by using the plating bath which remainder consists of Al and an unavoidable impurity. This is because Mg 2 Si having a major axis of 5 ⁇ m or more can be more reliably formed in the plating layer obtained by the above method, and Mn can be more reliably taken into the interface alloy layer.
  • composition of the plating layer of the hot-dip Al-based plated steel sheet of the present invention is almost the same as the composition of the plating bath. Therefore, the composition of the plating layer can be controlled with high accuracy by controlling the plating bath composition. Moreover, the control of the composition of the interface alloy layer formed by the reaction between the plating bath and the steel plate can also be performed with high accuracy by controlling the plating bath composition.
  • the plating bath contains 6 to 15% by mass of Mg.
  • Mg contained in the plating bath is mainly distributed to the plating layer in the solidification process, and can form the above-described large particle size Mg 2 Si, which contributes to improvement of corrosion resistance after coating.
  • the Mg content is less than 6 mass, a sufficient amount of Mg 2 Si with a large particle size cannot be formed, and the destruction of the Al oxide film that can suppress the selective corrosion of the interdendrite does not occur. The improvement in corrosion resistance after painting cannot be expected.
  • the Mg content exceeds 15% by mass, the plating bath is remarkably oxidized and stable operation becomes difficult. Therefore, from the viewpoint of obtaining excellent post-coating corrosion resistance and plating layer manufacturability, the Mg content is in the range of 6 to 15%. From the same viewpoint, the Mg content is preferably 7 to 10% by mass.
  • the plating bath contains more than 7 mass% and not more than 20 mass% of Si.
  • Si content is 7% by mass or less, there is a possibility that Mg 2 Si having the large particle diameter described above cannot be reliably formed when the plating layer is solidified.
  • the Si content exceeds 20%, the FeAl 3 Si 2 intermetallic compound to be reduced is generated in the interface alloy layer described later, so that the workability of the plated layer and the post-working corrosion resistance are lowered. Therefore, from the viewpoint of achieving both excellent post-coating corrosion resistance and post-processing corrosion resistance, the Si content is more than 7 mass% and not more than 20 mass%, preferably 7.5 to 15 mass%, preferably 8 to 10 mass%. It is more preferable to set it as the mass%.
  • the composition of the plating bath preferably satisfies the following formula (1).
  • Equation (1) MIN ⁇ Si% ⁇ ([Mg 2 Si] mol / [Si] mol), Mg% ⁇ ([Mg 2 Si] mol / (2 ⁇ [Mg] mol)) ⁇ / Al%> 0.13
  • M% represents the mass% concentration of the element M in the plating bath
  • [M] mol represents the molar mass of the element M in the plating bath.
  • MIN (a, b) indicates a smaller value of a and b.
  • Al-Mg 2 Si eutectic point of pseudo-binary system of the plating layer is in the 86.1% Al-13.9% Mg 2 Si by mass%, a large particle diameter by the Mg 2 Si excess than this Mg 2 Si can be deposited in the plating layer.
  • the bath composition for obtaining the eutectic plating layer is approximately 88.5% Al-11.5% Mg 2 Si.
  • the calculated maximum Mg 2 Si% formed by Mg and Si in the plating layer is determined by the number of moles of Mg and the number of moles of Si.
  • the number of moles of Mg exceeds twice the number of moles of Si.
  • Si% ⁇ ([Mg 2 Si] mol / [Si] mol ).
  • the calculated maximum Mg 2 Si% formed of Mg and Si in the plating layer is Mg%. ⁇ ([Mg 2 Si] mol / (2 ⁇ [Mg] mol )).
  • the calculated Mg 2 Si% is MIN ⁇ Si% ⁇ ([Mg 2 Si] mol / [Si] mol ), Mg % ⁇ ([Mg 2 Si] mol / (2 ⁇ [Mg] mol )) ⁇ . From these, it is preferable that the composition of the plating bath satisfies the above formula (1), and the formula (2): MIN ⁇ Si% ⁇ ([Mg 2 Si] mol / [Si] mol ), Mg% It is more preferable that x ([Mg 2 Si] mol / (2 ⁇ [Mg] mol )) ⁇ / Al%> 0.15 is satisfied.
  • the plating bath may contain 0.01 to 1% by mass of Fe.
  • Fe is an element contained in the plating bath as a result of the Fe dissolved from the underlying steel plate being mixed into the plating bath when the plating layer is formed.
  • the said plating bath contains Mn more than 0.5 mass% and 2.5 mass% or less.
  • Mn is dissolved in ⁇ -AlFeSi, which is a compound contained in the interface alloy layer and the plating layer, to form ⁇ -Al (Fe, Mn) Si. Since ⁇ -AlFeSi exhibits a higher potential than Fe and Al, it functions as a local cathode during the corrosion of the plating layer, and the corrosion of the plating layer is accelerated by increasing its volume fraction.
  • ⁇ -Al (Fe, Mn) Si in which Mn is dissolved is known to show a significantly lower potential than ⁇ -AlFeSi.
  • Mn content in the plating bath is more than 0.5% by mass and not more than 2.5% by mass, preferably 0.5 to 2.0% by mass, more preferably 0.8 to 1.2% by mass.
  • the Mn content is 0.5% by mass or less, there is a possibility that sufficient workability and work corrosion resistance cannot be obtained because the amount of Mn taken into the interface alloy layer is small.
  • the upper limit of the Mn content is 2.5% by mass because of the relationship of the saturated dissolution amount of Mn in the plating bath.
  • the ratio of the contents of Mg and Mn in the plating bath is important from the viewpoint of achieving both high levels of post-coating corrosion resistance and post-processing corrosion resistance.
  • the ratio of the Mn content (mass%) to the Mg content (mass%) in the plating bath is preferably 0.003 to 0.3. 0.03-0.3 is more preferable, and 0.1-0.3 is particularly preferable. If the ratio of the content of Mn to the content of Mg in the plating bath is less than 0.003, the amount of Mn taken into the interface alloy layer is not sufficient, and there is a possibility that sufficient corrosion resistance after processing may not be obtained. On the other hand, if the ratio of the content of Mn to the content of Mg in the plating bath exceeds 0.3, the formation of Mg 2 Si having a large particle size cannot be sufficiently formed, and the corrosion resistance after coating may be reduced. .
  • the plating bath contains Al in addition to the above-mentioned Mg, Si and Mn.
  • the content of Al, which is the main component of the plating bath, is preferably 50% by mass or more, more preferably more than 75% by mass, and still more preferably more than 80% by mass from the balance between corrosion resistance and operation.
  • the film thickness of the plated film of the hot-dip Al-based plated steel sheet of the present invention is preferably 10 to 35 ⁇ m per side. This is because excellent corrosion resistance can be obtained when the thickness of the plating film is 10 ⁇ m or more, and excellent workability can be obtained when the thickness is 35 ⁇ m or less. From the viewpoint of obtaining better corrosion resistance and workability, the thickness of the plating film is preferably 12 to 30 ⁇ m, more preferably 14 to 25 ⁇ m. Furthermore, the film thickness of the plating film is more preferably 15 ⁇ m or more considering that the molten Al-based plated steel sheet of the present invention forms Mg 2 Si having a large particle size.
  • the plating includes a base steel plate component taken into the plating by a reaction between the plating bath and the base steel plate during the plating process, and inevitable impurities in the plating bath.
  • Fe is contained in the order of several% to several tens%.
  • the inevitable impurities in the plating bath include Fe, Cr, Cu, Mo, Ni, and Zr.
  • the total content of inevitable impurities is not particularly limited, but from the viewpoint of maintaining the corrosion resistance and uniform solubility of plating, the total amount of inevitable impurities excluding Fe is preferably 1% by mass or less.
  • the plating bath is selected from Ca, Sr, V, Cr, Mo, Ti, Ni, Co, Sb, Zr, and B, as long as the effects of the present invention are not impaired, apart from the inevitable impurities described above. It is also possible to contain one or two or more kinds of elements (hereinafter sometimes referred to as “optionally contained elements”). However, from the viewpoint of more reliably obtaining a large particle size Mg 2 Si, it is preferable that these optional elements are not included in the plating. Since these elements react with Al, Fe, or Si to form intermetallic compounds and become nucleation sites, the formation of Mg 2 Si having a large particle size may be hindered.
  • the hot-dip Al-based plated steel sheet of the present invention can further include a chemical conversion film on the surface thereof.
  • the type of the chemical conversion film is not particularly limited, and chromate-free chemical conversion treatment, chromate-containing chemical conversion treatment, zinc phosphate-containing chemical conversion treatment, zirconium oxide-based chemical conversion treatment, and the like can be used.
  • silica fine particles either wet silica or dry silica may be used, but it is more preferable that silica fine particles having a large effect of improving adhesion, particularly dry silica, be contained.
  • the phosphoric acid and the phosphoric acid compound include those containing at least one selected from orthophosphoric acid, pyrophosphoric acid, polyphosphoric acid, and metal salts and compounds thereof.
  • the hot-dip Al-based plated steel sheet of the present invention can further include a coating film on the chemical conversion coating on the surface or the chemical conversion coating.
  • the paint used for forming the coating film is not particularly limited.
  • a polyester resin, an amino resin, an epoxy resin, an acrylic resin, a urethane resin, a fluorine resin, or the like can be used.
  • a roll coater, bar coater, spray, curtain flow, electrodeposition, or the like can be used as a method for applying the paint, and the method is not limited to a specific coating method.
  • the base steel plate used for the hot-dip Al type plated steel sheet of the present invention does not specifically limit about the base steel plate used for the hot-dip Al type plated steel sheet of the present invention, and it can be used not only for the same steel plate as the steel plate used for the normal hot-dip Al type plated steel plate but also for a high-strength steel plate and the like.
  • a hot-rolled steel plate or steel strip that has been pickled and descaled, or a cold-rolled steel plate or steel strip obtained by cold rolling them can be used.
  • the method for producing a hot-dip Al-plated steel sheet according to the present invention includes: Mg: 6 to 15% by mass; Si: more than 7% by mass and 20% by mass or less; and Mn: more than 0.5% by mass and 2.5% by mass or less in a plating facility. It is characterized by using a plating bath containing Al and inevitable impurities. With such a production method, it is possible to produce a hot-dip Al-based plated steel sheet that has normal corrosion resistance and is excellent in post-coating corrosion resistance and post-processing corrosion resistance.
  • a method of manufacturing in a continuous hot-dip plating facility is usually employed. In this method, since the base steel sheet is immersed in a plating bath and plating is performed, plating is performed on both surfaces of the steel sheet.
  • base steel sheet used in the hot-dip Al-based plated steel sheet of the present invention there are no particular limitations on the type of base steel sheet used in the hot-dip Al-based plated steel sheet of the present invention.
  • a hot-rolled steel plate or steel strip that has been pickled and descaled, or a cold-rolled steel plate or steel strip obtained by cold rolling them can be used.
  • it does not specifically limit about the conditions of the said pre-processing process and annealing process Arbitrary methods are employable.
  • the pickling step performed after the hot rolling may be performed by a commonly used method, and examples thereof include cleaning using hydrochloric acid or sulfuric acid.
  • the cold rolling process performed after the pickling is not particularly limited, but can be performed at a rolling reduction of 30 to 90%, for example. If the rolling reduction is 30% or more, the mechanical properties do not deteriorate, while if it is 90% or less, the rolling cost does not increase.
  • the recrystallization annealing step for example, after cleaning by degreasing and the like, using an annealing furnace, heat treatment is performed to heat the steel sheet to a predetermined temperature in the preceding heating zone, and predetermined heat treatment is performed in the latter soaking zone. Can be applied. It is preferred to process at temperature conditions that have the required mechanical properties.
  • the atmosphere in an annealing furnace anneals with Fe in a reducing atmosphere.
  • the kind of reducing gas is not specifically limited, It is preferable to use the reducing gas atmosphere already generally used.
  • the plating bath used in the method for producing a hot-dip Al-plated steel sheet according to the present invention includes Mg: 6 to 15% by mass, Si: more than 7% by mass and not more than 20% by mass, and Mn: more than 0.5% by mass and not more than 2.5% by mass. And the balance is made of Al and inevitable impurities.
  • the plating bath may contain about 0.01 to 1% by mass of Fe.
  • inevitable impurities and optional contained elements are the same as those described in the hot-dip Al-based plated steel sheet of the present invention.
  • the temperature of the plating bath is preferably in the range of (solidification start temperature + 20 ° C.) to 700 ° C.
  • the lower limit of the bath temperature was set to the solidification start temperature + 20 ° C.
  • the bath temperature was set to be equal to or higher than the freezing point of the plating raw material and the solidification start temperature + 20 ° C. This is to prevent local coagulation of the composition component due to the local decrease in bath temperature.
  • the upper limit of the bath temperature is set to 700 ° C. When the bath temperature exceeds 700 ° C., rapid cooling of the plating becomes difficult, and the main component is Al—Fe formed at the interface with the plated steel plate. This is because the thickness of the interface alloy layer is increased.
  • the temperature of the base steel sheet that penetrates into the plating bath is not particularly limited, but from the viewpoint of ensuring plating characteristics and preventing changes in bath temperature in the continuous hot-dip plating operation, It is preferable to control the temperature within ⁇ 20 ° C.
  • the immersion time of the base steel sheet in the plating bath is preferably 0.5 seconds or more.
  • the immersion time is less than 0.5 seconds, there is a possibility that a sufficient plating layer cannot be formed on the surface of the base steel plate.
  • the upper limit of the immersion time is not particularly limited, but if the immersion time is increased, the thickness of the Al—Fe alloy layer formed between the plating layer and the steel sheet may be increased. Preferably there is.
  • the conditions for immersing the base steel sheet in the plating bath there are no particular limitations on the conditions for immersing the base steel sheet in the plating bath.
  • it when performing plating on mild steel thin materials, it can be performed at a line speed of about 150 to 230 mpm, and when plating on thick materials, it can be performed at a line speed of about 40 mpm.
  • the steel sheet after the hot dip plating that has passed through the plating bath at a cooling rate of less than 15 K / s.
  • a gentle cooling process of less than 15 K / s after performing the hot dipping using the above-described plating bath Mg 2 Si having a larger major axis exceeding 5 ⁇ m can be formed during plating. Furthermore, it is possible to reduce the thickness of the interface alloy layer formed at the interface with the plated steel plate.
  • the cooling rate is less than 5 K / s, the solidification of the plating will be slow, resulting in a dripping pattern on the plating surface, resulting in a noticeable deterioration in appearance and a decrease in chemical conversion treatment. It is preferable to do. From the same viewpoint, the cooling rate is particularly preferably 8 to 12 K / s.
  • the method for producing a hot-dip Al-based plated steel sheet according to the present invention it is preferable to use nitrogen gas cooling for the cooling treatment.
  • the reason for adopting the nitrogen gas cooling is that it is not necessary to extremely increase the cooling rate as described above, and because it does not require a large-scale cooling facility, it is excellent in economic efficiency.
  • a hot-dip Al type plated steel plate can be manufactured in accordance with a conventional method.
  • a chemical conversion treatment film can be provided on the surface of the molten Al-based plated steel sheet (chemical conversion treatment step), or a coating film can be separately provided in a coating facility (coating film formation step).
  • samples 1-24 For all the hot-dip Al-based plated steel sheets used as samples, cold-rolled steel sheets with a thickness of 0.8 mm manufactured in a conventional manner are used as the base steel sheet.
  • the composition of the plating bath was changed to various conditions at a line speed of 200 mpm and an immersion time of 2 seconds to produce a molten Al-based plated steel sheet for each sample.
  • about the composition of the plating bath about 2 g was extracted from the plating bath used for the production of the sample, and the bath composition was confirmed by chemical analysis. Table 1 shows the composition of the plating bath of each sample. Note that the balance of the plating bath is Al and inevitable impurities.
  • the cooling rate of cooling with nitrogen gas after immersion in the plating bath is shown in Table 1. Moreover, about the film thickness of the said plating film, it was set as the average value of 10 points
  • the thickness of the plating film obtained by this method includes the thickness of the interface alloy layer. Table 1 shows the thickness of the plating film of each sample. Furthermore, for the composition of the interfacial alloy layer, from the molten Al-based plated steel sheet of each sample, any three sections were cut by shearing, and the average of semi-quantitative analysis values measured by EDX at any five points of the interfacial alloy layer Values were used.
  • Table 1 shows the composition of the interfacial alloy layer of each sample. Further, in the cross section cut out by the shearing process, the cross section in the plate thickness direction of the plating layer was observed in a range of 1 mm in the plate width direction with a scanning electron microscope (SEM), and the major axis of Mg 2 Si in the plating layer was measured. Table 1 shows the major axis of Mg 2 Si of each sample.
  • Zinc phosphate treatment Defluorinating agent manufactured by Nihon Parkerizing Co., Ltd .: FC-E2001, surface conditioning agent: PL-X, and chemical conversion treatment agent: PB-AX35 (temperature: 35 ° C) Chemical conversion treatment was performed under the conditions of a concentration of 200 ppm by mass and an immersion time of the chemical conversion solution of 120 seconds.
  • Electrodeposition coating Electrodeposition coating made by Kansai Paint Co., Ltd .: Using GT-100, electrodeposition coating was applied so that the film thickness was 15 ⁇ m. After chemical conversion treatment and electrodeposition coating, as shown in Fig.
  • a molten Al-based plated steel sheet and a method for producing the molten Al-based plated steel sheet which are excellent in post-coating corrosion resistance and post-processing corrosion resistance.

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Abstract

Le but de la présente invention est de fournir une tôle d'acier revêtue d'Al par immersion à chaud qui présente une excellente résistance à la corrosion après revêtement et une excellente résistance à la corrosion après traitement. Afin de résoudre le problème décrit ci-dessus, une tôle d'acier revêtue d'Al par immersion à chaud selon la présente invention est pourvue d'un film de revêtement qui est composé d'une couche de revêtement et d'une couche d'alliage interfaciale qui est présente au niveau de l'interface entre la couche de revêtement et une tôle d'acier de base; et cette tôle d'acier revêtue d'Al par immersion à chaud est caractérisée en ce que la couche d'alliage interfaciale contient du Mn et en ce que la couche de revêtement contient une phase de Mg2Si qui a une longueur de 5 µm ou plus.
PCT/JP2018/012570 2017-03-31 2018-03-27 TÔLE D'ACIER REVÊTUE D'Al PAR IMMERSION À CHAUD ET SON PROCÉDÉ DE PRODUCTION WO2018181392A1 (fr)

Priority Applications (4)

Application Number Priority Date Filing Date Title
CN201880014986.4A CN110352261B (zh) 2017-03-31 2018-03-27 热浸镀Al系钢板及其制造方法
US16/489,848 US10822685B2 (en) 2017-03-31 2018-03-27 Hot-dip Al alloy coated steel sheet and method of producing same
EP18776826.2A EP3604604A4 (fr) 2017-03-31 2018-03-27 TÔLE D'ACIER REVÊTUE D'Al PAR IMMERSION À CHAUD ET SON PROCÉDÉ DE PRODUCTION
MX2019011384A MX2019011384A (es) 2017-03-31 2018-03-27 Lamina de acero recubierta de aleacion de al por inmersion en caliente y metodo de produccion de la misma.

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Cited By (1)

* Cited by examiner, † Cited by third party
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WO2023176100A1 (fr) * 2022-03-14 2023-09-21 Ｊｆｅスチール株式会社 Élément pressé à chaud, feuille d'acier pour pressage à chaud, procédé de production d'élément pressé à chaud, et procédé de production de feuille d'acier pour pressage à chaud

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Publication number Priority date Publication date Assignee Title
JPS5430022B1 (fr) 1970-10-27 1979-09-27
JP2000239820A (ja) 1998-12-25 2000-09-05 Nippon Steel Corp 耐食性に優れた溶融アルミめっき鋼板
WO2007029322A1 (fr) * 2005-09-01 2007-03-15 Nippon Steel Corporation PRODUIT EN ACIER PLAQUE D’UN ALLIAGE A BASE DE Zn-Al PAR IMMERSION A CHAUD PRESENTANT UNE EXCELLENTE APTITUDE A LA FLEXION ET SON PROCEDE DE FABRICATION
JP4199404B2 (ja) 1999-03-15 2008-12-17 新日本製鐵株式会社 高耐食性めっき鋼板
JP2012007245A (ja) * 1999-03-19 2012-01-12 Nippon Steel Corp 耐食性に優れた錫めっき系またはアルミめっき系表面処理鋼材

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5430022B1 (fr) 1970-10-27 1979-09-27
JP2000239820A (ja) 1998-12-25 2000-09-05 Nippon Steel Corp 耐食性に優れた溶融アルミめっき鋼板
JP4199404B2 (ja) 1999-03-15 2008-12-17 新日本製鐵株式会社 高耐食性めっき鋼板
JP2012007245A (ja) * 1999-03-19 2012-01-12 Nippon Steel Corp 耐食性に優れた錫めっき系またはアルミめっき系表面処理鋼材
WO2007029322A1 (fr) * 2005-09-01 2007-03-15 Nippon Steel Corporation PRODUIT EN ACIER PLAQUE D’UN ALLIAGE A BASE DE Zn-Al PAR IMMERSION A CHAUD PRESENTANT UNE EXCELLENTE APTITUDE A LA FLEXION ET SON PROCEDE DE FABRICATION

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023176100A1 (fr) * 2022-03-14 2023-09-21 Ｊｆｅスチール株式会社 Élément pressé à chaud, feuille d'acier pour pressage à chaud, procédé de production d'élément pressé à chaud, et procédé de production de feuille d'acier pour pressage à chaud
JP7485219B2 (ja) 2022-03-14 2024-05-16 Ｊｆｅスチール株式会社 熱間プレス部材および熱間プレス用鋼板、ならびにそれらの製造方法

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