CN115427602A - Hot-dip plated steel sheet and method for producing same - Google Patents
Hot-dip plated steel sheet and method for producing same Download PDFInfo
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- CN115427602A CN115427602A CN202180029472.8A CN202180029472A CN115427602A CN 115427602 A CN115427602 A CN 115427602A CN 202180029472 A CN202180029472 A CN 202180029472A CN 115427602 A CN115427602 A CN 115427602A
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- 239000010959 steel Substances 0.000 title claims abstract description 164
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- 238000007747 plating Methods 0.000 claims abstract description 90
- 239000010410 layer Substances 0.000 claims abstract description 89
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- 238000003618 dip coating Methods 0.000 claims abstract description 28
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- 239000002585 base Substances 0.000 claims description 82
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- 238000005238 degreasing Methods 0.000 claims description 27
- 239000003513 alkali Substances 0.000 claims description 26
- 239000004094 surface-active agent Substances 0.000 claims description 11
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 229910052759 nickel Inorganic materials 0.000 claims description 8
- 238000000137 annealing Methods 0.000 claims description 6
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- 241000605447 Anemarrhena Species 0.000 description 1
- 229910019064 Mg-Si Inorganic materials 0.000 description 1
- 229910017706 MgZn Inorganic materials 0.000 description 1
- 229910019406 Mg—Si Inorganic materials 0.000 description 1
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- 239000010960 cold rolled steel Substances 0.000 description 1
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Images
Classifications
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- 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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/022—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by heating
-
- 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
- C23C2/06—Zinc or cadmium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C18/00—Alloys based on zinc
- C22C18/04—Alloys based on zinc with aluminium 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
- C23C2/02—Pretreatment of the material to be coated, e.g. for coating on selected surface areas
- C23C2/024—Pretreatment of the material to be coated, e.g. for coating on selected surface areas by cleaning or etching
-
- 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
- C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
- C23C2/36—Elongated material
- C23C2/40—Plates; Strips
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- 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
- C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
- C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
- C23G1/14—Cleaning or pickling metallic material with solutions or molten salts with alkaline solutions
- C23G1/19—Iron or steel
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Coating With Molten Metal (AREA)
Abstract
The hot-dip plated steel sheet according to an aspect of the present invention includes a base steel sheet and a hot-dip plating layer, and the chemical composition of the hot-dip plating layer contains Al:4.0 to 22 mass%, mg:1 to 10 mass%, and Si: 0.0001-2 mass%, the balance of Zn and impurities, and the total amount of the hot dip coating layers on both surfaces is 40-600 g/m 2 An interface Mg existing at an interface between the base steel sheet and the hot-dip coating layer, measured in a vertical cross-sectional view of 10mm in length 2 Phase of SiThe total of the interfacial contact length of (a) is 20% or less of the visual field, and an interfacial Mg having an equivalent circle diameter of 30 μm or more is present at the interface between the base steel sheet and the hot-dip coating layer 2 The number density of the Si phase measured in a plan view is 10 pieces/mm 2 The following.
Description
Technical Field
The present invention relates to a hot-dip coated steel sheet and a method for producing the same.
This application claims priority based on Japanese application No. 2020-075495 on 21/4/2020, and the content thereof is incorporated herein by reference.
Background
The Zn-Al-Mg hot-dip coated steel sheet has high corrosion resistance. Further, the Zn — Al — Mg — Si hot-dip coated steel sheet containing a small amount of Si is excellent in both corrosion resistance and workability. Therefore, zn — Al — Mg hot-dip coated steel sheets and Zn — Al — Mg — Si hot-dip coated steel sheets are used in various technical fields such as the building material field, the household electrical appliance field, and the automobile field.
Patent document 2 discloses a steelA highly corrosion-resistant hot-dip galvanized steel sheet having a plating layer formed on the surface thereof and having excellent uniformity in appearance, the plating layer containing Al:4 to 22 mass%, mg:1 to 6 mass%, si:0.001 to 1 mass%, the remainder being Zn and unavoidable impurities; in the steel sheet, mg is present at the interface between the plating layer and the base steel sheet 2 A Si phase and a Ca phase containing Ca or a Ca compound as a main component, and Mg 2 At least a part of the Si phase precipitates with the Ca phase as a nucleus.
Patent document 3 discloses an aluminum-plated steel sheet having excellent corrosion resistance and appearance, which is characterized by having a plating layer on at least one surface of the steel sheet, the plating layer comprising, in mass%, si:2% or more and 11% or less, mg:3% or more and 9% or less, ca:0.1% to 5%, ti:0.005% to 0.05%, the balance of Al and unavoidable impurities, and Mg is present in the plating layer 2 Si particles of the Mg 2 The Si particles have a major axis of 10 μm or less and an aspect ratio of 1 to 3, which is the ratio of the major axis to the minor axis.
Documents of the prior art
Patent document
Patent document 1: japanese patent laid-open publication No. 2013-14794
Patent document 2: recommendations Table WO2013/002358 publication
Patent document 3: re-publication table WO2013/008341
Disclosure of Invention
Technical problems to be solved by the invention
The present inventors have recognized that: in a coated steel sheet obtained by coating a Zn — Al — Mg — Si hot-dip coated steel sheet, coating film peeling is likely to occur. As a result of detailed examination of the coated steel sheet in which the coating film was peeled off, it was found that: there is a tendency that the coating film is peeled off at the interface between the plating layer and the base steel sheet. This result indicates that there is a concern about the processed portion plating adhesion of the Zn — Al — Mg — Si hot dip plated steel sheet. The processed portion plating adhesion means adhesion of plating at a position to which mechanical processing such as bending processing or drawing processing is applied.
Hot dip galvanized steel sheet of Zn-Al-Mg system, or Zn-AlIn the prior art of-Mg-Si hot-dip plated steel sheet, there are few examples focusing on the plating adhesion of the processed portion. In the above prior art document, patent document 3 discloses: spherical Mg 2 Si particles reduce stress concentration during high stress forming processes, resulting in reduced initiation and propagation of latent cracks (craks). However, in patent document 3, no study is made on the peeling of the plating layer.
In view of the above circumstances, an object of the present invention is to provide a high corrosion-resistant hot-dip plated steel sheet having excellent work portion plating adhesion, and a method for producing the same.
Means for solving the problems
The gist of the present invention is as follows.
(1) The hot-dip coated steel sheet according to one aspect of the present invention includes a base steel sheet and a hot-dip coating layer, the chemical composition of the hot-dip coating layer containing Al:4.0 to 22 mass%, mg:1 to 10 mass% and Si: 0.0001-2 mass%, the balance consisting of Zn and impurities, and the amount of the hot-dip coating layer deposited on both surfaces is 40-600 g/m in total 2 An interface Mg existing at an interface between the base steel sheet and the hot-dip coating layer, measured in a vertical cross-sectional view of 10mm in length 2 The total of the interfacial contact length of the Si phase is 20% or less of the visual field, and the interfacial Mg having an equivalent circle diameter of 30 [ mu ] m or more is present at the interface between the base steel sheet and the hot-dip coating layer 2 The number density of the Si phase measured in a plan view is 10 pieces/mm 2 The following.
(2) In the hot-dip galvanized steel sheet described in the above (1), the interface Mg measured in a 10mm long visual field of the vertical cross section may be 2 The maximum value of the interfacial contact length of the Si phase is 50 [ mu ] m or less.
(3) In the hot-dip coated steel sheet described in the above (1) or (2), the interfacial Mg may be present in the interface 2 The ratio b/a of the length a of the Si phase in the depth direction of the plating layer to the length b of the interface in the horizontal direction is 0.1 to 10 in the field of view of the length of 10mm in the vertical cross section.
(4) In the hot-dip coated steel sheet according to any one of (1) to (3), the chemical component of the hot-dip coating layer may contain, in place of part of Zn, 0.001 to 2 mass% in total of 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf.
(5) In the hot-dip coated steel sheet according to any one of (1) to (4), the chemical component of the hot-dip coating layer may contain, in place of a part of Zn, 0.001 to 2% by mass in total of 1 or more selected from the group consisting of Ni, ti, zr, and Sr.
(6) A method of producing a hot dip coated steel sheet according to another aspect of the present invention is the method of producing a hot dip coated steel sheet according to any one of the above (1) to (5), including: a step of alkali degreasing the base steel sheet with an alkali degreasing solution containing 0.5 to 5.0 mass% of a surfactant; washing the base steel sheet after the alkali degreasing; annealing the base steel sheet after the water washing; and immersing the annealed base steel sheet in a solution containing Al:4.0 to 22 mass%, mg:1 to 10 mass%, si: and (3) forming a hot-dip coating layer in a hot-dip plating bath containing 0.0001 to 2 mass% of Zn and impurities as the remainder, wherein the pH of the washing water is set to be not less than 8.7 and not more than 12 at all times in the washing with water.
(7) In the method of producing a hot-dip galvanized steel sheet according to (6), the hot-dip plating bath may contain, in place of a part of Zn, 0.001 to 2 mass% in total of 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf.
(8) In the method for producing a hot-dip plated steel sheet according to (6) or (7), the hot-dip plating bath may contain, in place of a part of Zn, 0.001 to 2% by mass in total of 1 or more selected from the group consisting of Ni, ti, zr, and Sr.
Effects of the invention
According to the present invention, it is possible to provide a high corrosion-resistant hot-dip plated steel sheet having excellent working portion plating adhesion and a method for producing the same.
Drawings
Fig. 1 is a schematic cross-sectional view of a highly corrosion-resistant hot-dip plated steel sheet having excellent processed portion plating adhesion according to one embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view of a high corrosion-resistant hot-dip plated steel sheet having excellent processed portion plating adhesion according to one embodiment of the present invention.
Detailed Description
The present inventors have carried out a detailed structural analysis of plating separation occurring in a processed portion when a plated steel sheet is provided in a test simulating stress forming processing such as a 180 ° bending test. As a result, mg in the interface between the steel sheet of anemarrhena material and the plating layer 2 The crystal form of the Si phase greatly affects the plating adhesion of the processed portion.
In a normal plated steel sheet, the Mg existing at the interface between the base steel sheet and the hot-dip plated layer 2 Si phase (hereinafter, referred to as "interfacial Mg 2 Si phase') in cross-sectional view, interface Mg 2 The Si phase exists along the interface. The present inventors have recognized that: by making the interface Mg 2 The length of the Si phase along the interface (interface contact length) decreases, and the processed portion plating adhesion improves. Furthermore, when the surface of the base steel sheet was observed by SEM after removing the plating layer of the plated steel sheet, the interface Mg was confirmed 2 The Si phase adheres to the base steel sheet. The present inventors have recognized that: by making the interface Mg 2 Interface Mg of equivalent circle diameter of 30 μm or more in Si phase 2 Si phase (coarse interface Mg) 2 Si phase) is decreased, and the processed portion is further improved in plating adhesion.
Further, the present inventors have recognized that: interfacial Mg measured in cross section 2 Interfacial contact length of Si phase and coarse interface Mg measured in plan view 2 The number density of the Si phase and the cleaning conditions before plating of the base steel sheet have close correlation. Also, the inventors have specified making the interface Mg 2 The state of the Si phase is in a preferable range.
The plating adhesion of one embodiment of the present invention obtained by the above knowledgeAs shown in fig. 1, for example, a highly corrosion-resistant hot-dip plated steel sheet 1 (hot-dip plated steel sheet 1 according to the present embodiment) having excellent properties includes a base steel sheet 11 and a hot-dip plated layer 12, and the chemical composition of hot-dip plated layer 12 contains Al:4.0 to 22 mass%, mg:1 to 10 mass% and Si: 0.0001-2 mass%, the balance being Zn and impurities, and the amount of the hot-dip coating layer 12 adhering to both surfaces being 40-600 g/m in total 2 Interfacial Mg measured in a vertical cross-section view of 10mm length 2 The total of the interfacial contact length of the Si phase 13 is 20% or less of the visual field, and the interface Mg having an equivalent circle diameter of 30 μm or more is present at the interface between the base steel sheet 11 and the hot-dip plated layer 12 2 The number density of the Si phase 13 measured in a plan view is 10 pieces/mm 2 The following.
The hot-dip plated steel sheet 1 of the present embodiment includes a base steel sheet 11. The kind of the base steel sheet 11 is not particularly limited. Various components, thicknesses, metal structures, mechanical properties, and the like can be applied to the base steel sheet 11 according to the application of the hot-dip coated steel sheet 1.
The hot-dip plated steel sheet 1 according to the present embodiment has a hot-dip plated layer 12, and the hot-dip plated layer 12 is disposed on the surface of the base steel sheet 11. The hot-dip plated layer 12 may be provided on one surface or both surfaces of the base steel sheet 11. First, the chemical composition of the hot-dip plated layer 12 will be described below. Hereinafter, unless otherwise specified, the unit "%" of the content of each element means mass%.
(Al: 4.0-22 mass%)
In the hot-dip plated layer 12, the content of Al is set to 4.0 mass% or more and 22 mass% or less. When the Al content is less than 4.0 mass%, it is considered that the effect of improving the corrosion resistance is not sufficiently obtained. When the Al content is 22 mass% or more, the effect of improving the corrosion resistance is considered to be saturated. In order to further improve the corrosion resistance, the content of Al may be 5 mass% or more, or 10 mass% or more. In addition, the content of Al may be 20 mass% or less, or 15 mass% or less in order to lower the melting point of the plating bath or to improve the plating adhesion.
(Mg: 1 to 10 mass%)
In the hot-dip plated layer 12, the Mg content is set to 1 mass% or more and 10 mass% or less. When the Mg content is less than 1 mass%, it is considered that the effect of improving the corrosion resistance is not sufficiently obtained. When the Mg content exceeds 10 mass%, the plating layer is considered to be brittle, and the adhesiveness of the plating is considered to be reduced. In order to further improve the corrosion resistance, the content of Mg may be 2 mass% or more, or 3 mass% or more. In order to further improve the adhesion of the plating layer, the Mg content may be 9 mass% or less, 7 mass% or less, 5 mass% or less, 4.5 mass% or less, or 4 mass% or less.
(Si: 0.0001-2 mass%)
In the hot-dip plated layer 12, the content of Si is set to 0.0001 mass% or more and 2 mass% or less. Si has an effect of improving the corrosion resistance of the hot-dip plated layer 12, but it is considered to be industrially difficult to control the content thereof to less than 0.0001 mass%. In addition, when the Si content is 2 mass% or more, the effect of improving the corrosion resistance is considered to be saturated. The Si content may be 0.001 mass% or more, or 0.01 mass% or more. The Si content may be 1.5 mass% or less, or 1.0 mass% or less.
(remainder: zn and impurities)
The remainder of the chemical composition of hot-dip coating layer 12 is Zn and impurities. The impurities are components mixed into the hot-dip plated layer 12 due to, for example, the raw materials of the hot-dip galvanized steel sheet or various factors of the production process, and are allowed within a range that does not adversely affect the hot-dip plated steel sheet 1 of the present embodiment.
The chemical composition of hot-dip coating layer 12 may contain, in place of a part of Zn constituting the remainder, 0.001 to 2 mass% in total of 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements (e.g., sc), REM, and Hf. When the content of these elements is 2% by mass or less, various properties such as corrosion resistance of hot-dip plated layer 12 are not impaired. In addition, the corrosion resistance of the hot-dip coating layer 12 may also be improved by these elements. The total amount of 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf may be 0.002% by mass or more, 0.01% by mass or more, or 0.1% by mass or more. The total amount of 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf may be 1.5 mass% or less, 1.0 mass% or less, or 0.5 mass% or less.
In addition, the chemical composition of hot-dip plating layer 12 may contain, in place of a part of Zn constituting the remaining portion, 0.001 to 2 mass% in total of 1 or more selected from the group consisting of Ni, ti, zr, and Sr. When the total content of these elements is 0.001 mass% or more, an intermetallic compound of these elements and Al is crystallized, and the surface smoothness is improved. However, when the total content of these elements exceeds 2 mass%, the appearance of the plating layer becomes rough, and there is a risk of appearance defects. The total amount of 1 or more selected from the group consisting of Ni, ti, zr, and Sr may be 0.002 mass% or more, 0.01 mass% or more, or 0.1 mass% or more. The total amount of 1 or more selected from the group consisting of Ni, ti, zr, and Sr may be 1.5 mass% or less, 1.0 mass% or less, or 0.5 mass% or less.
Next, the amount of deposit of hot-dip plated layer 12 will be described. The amount of deposit of the hot-dip coating layer 12 is 40 to 600g/m in total on both sides 2 Within the range of (1). By setting the adhesion amount of the hot-dip plated layer 12 to 40g/m 2 As described above, high corrosion resistance can be imparted to the hot-dip plated steel sheet 1. On the other hand, the amount of deposit of the hot-dip plated layer 12 is set to 600g/m 2 The plating adhesion (e.g., the processed portion plating adhesion) can be ensured as follows. The amount of deposit of the hot-dip plated layer 12 may be 50g/m in total on both sides 2 Above, 100g/m 2 Above, or 200g/m 2 The above. The amount of deposit of the hot-dip plated layer 12 may be 550g/m in total on both sides 2 500g/m below 2 Below, or 300g/m 2 The following.
In the hot-dip coated steel sheet 1 of the present embodiment, heat is applied to the base steel sheet 11At the interface of the immersion plating layer 12, mg may be present 2 A Si phase. Hereinafter, mg present at the interface between the base steel sheet 11 and the hot-dip plated layer 12 will be described 2 Si phase to interfacial Mg 2 And a Si phase 13. Further, an alloy layer having a thickness of about several hundred nm may be formed at the interface between the base steel sheet 11 and the hot-dip plated layer 12. In this case, mg in contact with the interface between the base steel sheet 11 and the alloy layer 2 Si phase and Mg in contact with the interface between the alloy layer and the hot-dip coating layer 12 2 Si phase and Mg in contact with both of these interfaces 2 The Si phases are all considered to be interfacial Mg 2 And a Si phase 13.
In the hot-dip coated steel sheet 1 of the present embodiment, the interface Mg measured in a vertical cross-sectional view of 10mm length 2 The total of the interfacial contact lengths of the Si phases 13 is 20% or less of the visual field.
Here, the interface Mg 2 The interfacial contact length of the Si phase 13 is the interfacial Mg content at the interface between the base steel sheet 11 and the hot-dip coating layer 12 2 Length of the portion contained in the Si phase. Referring to fig. 1 as an example, mg is present at the interface and each interface between base steel sheet 11 and hot-dip plated layer 12 2 The Si phase 13 is in contact at point 2. The distance between these 2 points is the interface Mg 2 Interfacial contact length of the Si phase 13.
So-called interfacial Mg measured in a vertical cross-section view of 10mm length 2 The total of the interfacial contact lengths of the Si phases 13 is the interfacial Mg contained in an arbitrary visual field perpendicular to the cut surface of the hot-dip coated steel sheet 1 2 The total value of the interfacial contact length of the Si phase 13. Here, the number of views is set to 5 views, and the average value of the total value of the interface contact lengths in each view is calculated. The shape of the visual field is 10mm square, and the interface between base steel sheet 11 and hot-dip plated layer 12 is set substantially parallel to the lateral side of the visual field. Taking FIG. 1 as an example, the view of FIG. 1 includes 3 interface Mg 2 The Si phase 13 has an interfacial contact length of L1 to L3. Interfacial Mg measured in a field of view perpendicular to a cross section of 10mm length 2 The total of the interfacial contact lengths of the Si phase 13 is L1+ L2+ L3.
In the hot-dip coated steel sheet 1 of the present embodiment, the total interfacial contact length is based on the visual fieldThe ratio of (2) to (10 mm) defines the interface Mg 2 State of Si phase 13. At the interface Mg 2 When the total of the interfacial contact lengths of the Si phases 13 (average of 5 fields of view) is 20% or less of the field of view, the area of the region where the plating layer is likely to peel off is reduced, and the plating adhesion of the highly processed portion is obtained. Or, the interface is Mg 2 The total of the interfacial contact lengths of the Si phases 13 is 18% or less, 15% or less, or 10% or less of the visual field.
From the viewpoint of ensuring the plating adhesion of the processed portion, the interface Mg 2 The lower limit of the total interfacial contact length of the Si phase 13 is not particularly limited. Thus, interfacial Mg 2 The total of the interfacial contact lengths of the Si phases 13 may be 0% of the visual field. However, it is also possible to Mg the interface 2 The total of the interfacial contact lengths of the Si phases 13 is 0.5% or more of the visual field. Optionally, the interface is Mg 2 The total of the interfacial contact lengths of the Si phases 13 is 1.0% or more, 2.0% or more, or 5.0% or more of the field of view.
In the hot-dip coated steel sheet 1 of the present embodiment, the interface Mg having an equivalent circle diameter of 30 μm or more is present at the interface between the base steel sheet and the hot-dip coated layer 2 Si phase (hereinafter, referred to as "coarse interface Mg 2 Si phase ") of 10 pieces/mm in number density as measured in a plan view 2 The following. The "plan view" refers to a view when viewed from a direction perpendicular to the interface or the base steel sheet. It should be noted here that the interface Mg with the above-mentioned 2 In contrast to the case where the interfacial contact length of the Si phase 13 is measured in the cross section of the hot-dip galvanized steel sheet 1, the coarse interface Mg 2 The number density of the Si phase is measured on the surface of the base steel sheet in a plan view. Specifically, coarse interface Mg 2 The number density of the Si phase was measured by the following procedure.
1. The hot-dip plated steel sheet was dipped in 0.5% hydrochloric acid to which an inhibitor was added. Thereby, the hot-dip plated layer can be dissolved and removed from the hot-dip plated steel sheet. On the other hand, the interface Mg existing at the interface between the base steel sheet and the hot-dip plated layer 2 The Si phase remains on the surface of the base steel sheet.
2. By SEM observation, the interface Mg with an equivalent circle diameter of 30 μm or more contained in any 1mm square region on the surface of the base steel sheet 2 Si phase (coarse interface Mg) 2 Si phase) was counted. Here, the number of arbitrary 1mm square regions to be observed was set to 5, and the coarse interface Mg in each region was calculated 2 Average value of the number of Si phases. The average value was taken as interface Mg 2 Si phase (coarse interface Mg) 2 Si phase) number density. Here, interface Mg 2 The equivalent circle diameter of the Si phase is an equivalent circle diameter in a plan view of the base steel sheet.
Coarse interface Mg 2 The Si phase presents the following risks: in the cross-sectional observation, the image cannot be captured completely. Even if the interfacial contact length measured by cross-sectional observation is within the above range, there is a possibility that: there are coarse interfaces Mg not present in the cross section 2 A Si phase. If such coarse interface Mg exists 2 In the case of the Si phase, there is a risk that the plating adhesion of the processed portion of the hot-dip plated steel sheet is impaired. Now, the present inventors have evaluated various hot-dip plated steel sheets, and as a result, they have confirmed that the following are present: even in the interface Mg in the cross section 2 In a hot-dip galvanized steel sheet having a small interfacial contact length of Si phase, coarse interface Mg measured in a plan view 2 The number density of the Si phase also increases.
For the above reasons, in the hot-dip coated steel sheet of the present embodiment, the interface Mg is excluded 2 The sum of the interfacial contact lengths of the Si phases is set to be outside the above range, and the coarse interfacial Mg measured in a plan view 2 The number density of Si phases was also set to 10/mm 2 The following. Coarse interface Mg measured in plan view 2 The number density of Si phases exceeds 10/mm 2 In the case of (3), sufficient plating adhesion of the processed portion cannot be ensured. Coarse interface Mg measured in plan view 2 The number density of Si phases may be 9/mm 2 Below, 8 pieces/mm 2 Below, or 7/mm 2 The following. Coarse interface Mg measured in plan view 2 The lower limit is not particularly limited since the smaller the number density of the Si phase is, the better. In a top viewMeasured coarse interface Mg 2 The number density of the Si phases may be, for example, 0 phases/mm 2 Above, 1 piece/mm 2 Above, or 2/mm 2 As described above.
Furthermore, in the hot-dip galvanized steel sheet 1 of the present embodiment, it is preferable that the interface Mg be measured in a vertical cross-sectional view of 10mm in length 2 The maximum value of the interfacial contact length of the Si phase 13 is 50 μm or less. So-called interfacial Mg measured in a vertical cross-section view of 10mm length 2 The maximum value of the interfacial contact length of the Si phase 13 is the interface Mg contained in an arbitrary visual field of a cut surface perpendicular to the surface of the hot-dip coated steel sheet 1 2 The maximum value of the interfacial contact length of each Si phase 13. Further, the number of views was set to 5, and the interface Mg in each view was calculated 2 Average value of the maximum value of the interfacial contact length of the Si phase 13. Taking FIG. 1 as an example, the view of FIG. 1 includes 3 interface Mg 2 The maximum value among the interfacial contact lengths L1 to L3 of the Si phase 13 is L3. Thus, interfacial Mg measured in the field of view of FIG. 1 2 The maximum value of the interfacial contact length of the Si phase 13 is L3.
The interface Mg is presumed to be larger in the interface contact length 2 The more likely the Si phase 13 is to cause plating separation. Therefore, it is considered that not only the interface Mg included in the visual field can be made to pass 2 The ratio of the total interfacial contact length of the Si phase 13 in the visual field is reduced, and Mg is also applied to each interface 2 The interfacial contact length of the Si phase 13 is reduced, thereby further effectively suppressing plating peeling. For the above reasons, it is preferable that the interface Mg 2 The maximum value of the interfacial contact length of the Si phase 13 is 50 μm or less. Also, interface Mg 2 The maximum value of the interfacial contact length of the Si phase 13 is 45 μm or less, 40 μm or less, or 30 μm or less.
From the viewpoint of ensuring the plating adhesion of the processed part, the interface Mg 2 The lower limit of the maximum value of the interfacial contact length of the Si phase 13 is not particularly limited. Thus, interfacial Mg 2 The maximum value of the interfacial contact length of the Si phase 13 may be 0 μm. Complete absence of interfacial Mg in the measurement field 2 In the case of Si phase 13, interfacial Mg 2 Of Si phase 13The maximum value of the interfacial contact length becomes 0 μm. However, the interface Mg may be also applied in consideration of the capability of the manufacturing apparatus 2 The maximum value of the interfacial contact length of the Si phase 13 is 1 μm or more, 2 μm or more, or 5 μm or more.
Furthermore, in the hot-dip galvanized steel sheet 1 according to the present embodiment, the interface Mg may be 2 The ratio b/a of the length a of the Si phase 13 in the depth direction of the plating layer to the length b of the interface in the horizontal direction is 0.1 to 10 in a length field of view of 10mm in the vertical cross section. So-called interface Mg 2 The length a of the Si phase 13 in the depth direction of the plating layer is, as shown in FIG. 2, the interface Mg measured along the depth direction of the plating layer 2 The size of the Si phase 13. So-called interface Mg 2 The length b of the Si phase 13 in the horizontal direction of the interface, as shown in FIG. 2, is the interface Mg measured in the horizontal direction along the interface (i.e., the direction perpendicular to the depth direction of the plating layer) 2 The size of the Si phase 13. Hereinafter, the interface may be Mg 2 The ratio b/a of the length a of the Si phase 13 in the depth direction of the plating layer to the length b of the interface in the horizontal direction is called interface Mg 2 Aspect ratio of the Si phase 13. In addition, interface Mg 2 The aspect ratio of the Si phase 13 was evaluated in 5 fields. Contains more than 2 interfacial Mg in 5 visual fields 2 In the case of the Si phase 13, so-called "interfacial Mg 2 The ratio b/a of the length a of the Si phase 13 in the depth direction of the plating layer to the length b of the interface in the horizontal direction is 0.1 to 10 in a vertical cross-sectional 10mm length field, meaning that the Mg content of the entire interface in 5 fields is 0.1 to 10 ″ 2 The aspect ratio of the Si phase 13 is in the range of 0.1 to 10.
Interface Mg with large aspect ratio 2 The Si phase 13 has a shape extending along the interface between the base steel sheet 11 and the hot-dip plated layer 12. By mixing interface Mg 2 The aspect ratio of the Si phase 13 is 10 or less, and plating separation can be further effectively suppressed. Optionally, the interface is Mg 2 The aspect ratio of the Si phase 13 is 9 or less, 8 or less, or 5 or less.
Further, interface Mg with small aspect ratio 2 The Si phase 13 involves the following risks: when the hot-dip galvanized steel sheet 1 is processed, a plating crack propagation path is formed, and plating cracking and corrosion resistance deterioration occurLow. By mixing interface Mg 2 The aspect ratio of the Si phase 13 is 0.1 or more, and the corrosion resistance and the like of the hot-dip plated layer 12 can be further improved. Or, the interface is Mg 2 The aspect ratio of the Si phase 13 is 0.2 or more, 0.5 or more, or 1.0 or more.
The hot-dip plated steel sheet 1 according to the present embodiment may have a chemical conversion coating layer, a coating film layer, and the like on the surface of the hot-dip plated layer 12 for the purpose of, for example, improving design properties, corrosion resistance, and the like. Here, the kind of the chemical conversion coating layer and the coating layer is not particularly limited, and a known chemical conversion coating layer or coating layer can be applied. In this case, coarse interface Mg 2 The measurement of the number density of the Si phase can also be easily performed by: before the hot-dip coating is dissolved, the chemical conversion coating layer, the coating layer, and the like are appropriately removed by a known method.
Next, a method for producing a highly corrosion-resistant hot-dip plated steel sheet having excellent plating adhesion according to another embodiment of the present invention will be described. The method for producing a highly corrosion-resistant hot-dip plated steel sheet having excellent plating adhesion according to the present embodiment (hereinafter, the method for producing a hot-dip plated steel sheet according to the present embodiment may be omitted) includes: a step of performing alkali degreasing on the base steel sheet 11; a step of washing the base steel sheet 11 after the alkali degreasing; annealing the base steel sheet 11 after washing; and immersing the annealed base steel sheet 11 in a solution containing Al:4.0 to 22 mass%, mg:1 to 10 mass%, si: and a step of forming a hot-dip plated layer 12 by a hot-dip plating bath containing 0.0001 to 2 mass% of Zn and impurities as the remainder, wherein the pH of the washing water is set to a range of pH8.7 to 12 inclusive during the washing with water.
In the method of manufacturing the hot-dip plated steel sheet according to the present embodiment, first, the base steel sheet 11 is subjected to alkali degreasing. The alkali degreasing is performed with an alkali degreasing solution containing 0.5 to 5.0 mass% of a surfactant. By setting the concentration of the surfactant to 0.5% by mass or more, there is a possibility that interface Mg may be formed 2 The material of the crystal nuclei of the Si phase 13 is removed well from the surface of the base steel sheet 11. However, when the concentration of the surfactant exceeds 5.0 mass%, the following wind existsDanger: carbon constituting the surfactant attached to the surface of base steel sheet 11 remains on the surface of base steel sheet 11 even after annealing base steel sheet 11 described later. The carbon acts as interface Mg 2 The Si phase 13 has a crystal nucleus and an interface Mg is present 2 The interfacial contact length of the Si phase increases. For the above reasons, the surfactant concentration of the alkali degreasing solution for alkali degreasing is set to 0.5 to 5.0 mass%.
Subsequently, the base steel sheet 11 after the alkali degreasing is washed with water. The water washing is performed to remove the alkali degreasing solution from the surface of the base steel sheet 11. The liquid used for this washing is set to a ph of 8.7 or more and 12 or less. This prevents the interface Mg which may be generated from the liquid used for washing with water 2 The Si phase 13 is a component of crystal nuclei adhering to the base steel sheet 11.
Note that the ph of the washing water is set to be not less than 8.7 and not more than 12 during the washing. In the water washing of the normal cascade system, the final washing is performed with neutral water having a pH of about 7. However, in the method for producing a hot-dip galvanized steel sheet according to the present embodiment, neutral water is not used in the water washing. For example, when the base steel sheet 11 after the alkali degreasing is washed with water in a washing tank, the ph of the washing water contacting the base steel sheet 11 is set to 8.7 or more and 12 or less over the entire region from the entry side to the exit side of the washing tank. In the case where the pH of the washing water is not appropriate, that is, the pH is less than 8.7, in a part or all of the washing tank, the following cannot be sufficiently prevented: may become interface Mg 2 The Si phase 13 is a component of crystal nuclei adhering to the base steel sheet 11. On the other hand, if the washing water exceeds pH12, the dissolution of the surface of base steel sheet 11 becomes uneven, and there is a risk that the adhesion of the hot-dip plated layer becomes uneven, which is not preferable.
In this way, by setting the ph of the washing water in contact with the base steel sheet 11 to ph8.7 or more and 12 or less over the entire region from the entry side to the exit side of the washing tank, the possibility of interface Mg being formed can be prevented 2 The Si phase 13 is a component of crystal nuclei adhering to the base steel sheet 11. Therefore, in the subsequent process, the interface Mg 2 The generation of crystal nuclei of the Si phase 13 is carried outAnd (4) inhibiting. With this, interfacial Mg can be suppressed 2 The formation of the Si phase 13 can further suppress the coarsening due to aggregation and the like.
Then, the base steel sheet 11 after the water washing is annealed. Further, the annealed base steel sheet 11 is immersed in a hot-dip plating bath, and a hot-dip plated layer 12 is formed on the surface thereof. The annealing conditions are not particularly limited, and various conditions can be adopted depending on the composition, application, thickness, metal structure, mechanical properties, and the like of the base steel sheet 11. The components of the hot-dip plating bath may contain the same components as those of the hot-dip plating layer 12 of the hot-dip plated steel sheet of the present embodiment, i.e., al:4.0 to 22 mass%, mg:1 to 10 mass%, si:0.0001 to 2 mass%, the remainder being Zn and impurities. The preferable upper and lower limit values of the content of each element in the hot-dip plating bath are based on the preferable upper and lower limit values of the content of each element in the hot-dip plating layer 12. The hot-dip plating bath may contain, in place of part of Zn, 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf in total in an amount of 0.001 to 2% by mass. The chemical composition of the hot-dip plating bath may contain, in place of part of Zn, 0.001 to 2% by mass in total of 1 or more selected from the group consisting of Ni, ti, zr, and Sr.
In the case where the chemical conversion treatment layer is formed on the surface of the hot-dip plated layer 12, a chemical conversion treatment is performed on the hot-dip plated steel sheet on which the hot-dip plated layer is formed. The type of the chemical conversion treatment is not particularly limited, and a known chemical conversion treatment can be applied. When a coating layer is formed on the surface of the hot-dip plated layer 12, the surface of the chemical conversion layer, or the like, a coating process is performed on the hot-dip plated steel sheet on which the hot-dip plated layer or the chemical conversion layer is formed. The type of the coating treatment is not particularly limited, and a known coating treatment can be applied.
[ examples ] A
The effects of one embodiment of the present invention will be described in more detail by way of examples. However, the conditions in the examples are only one example of conditions adopted for confirming the possibility of carrying out the invention and the effects thereof. The present invention is not limited to this one condition example. As long as the object of the present invention is achieved without departing from the gist of the present invention, various conditions can be adopted in the present invention.
Various hot-dip plated steel sheets were produced through a step of alkali degreasing the base steel sheet, a step of washing the base steel sheet after alkali degreasing, a step of annealing the base steel sheet after washing, and a step of forming a hot-dip plating layer by immersing the annealed base steel sheet in a hot-dip plating bath.
The base steel sheet was a cold-rolled steel sheet having a thickness of 0.8mm in a state where cold rolling oil adhered thereto. When the base steel sheet was subjected to alkali degreasing, the concentration of the surfactant contained in the alkali degreasing solution was set as shown in table 1.
The pH of the washing water when washing the base steel sheet was set to 3 kinds as follows. The washing water used for the production of each example is shown in table 1.
A: the pH value is always above 8.7 and below 12 in water washing
B: in water washing, the pH is always less than 8.7
C: in washing, the pH is mainly 8.7-12, and part of the pH is less than 8.7
After the water-washed base steel sheet is annealed, the steel sheet is immersed in a hot-dip plating bath to form a hot-dip plated layer on the surface of the base steel sheet. The components of the hot-dip plating bath were as shown in table 1. The composition of the plating layer obtained in this way is substantially the same as the composition of the plating bath, and therefore, the description thereof is omitted in table 1 or table 2.
The amount of deposit of the hot-dip plated layer was adjusted by gas wiping after plating.
In table 1, values outside the scope of the invention are underlined. In addition, the contents of elements not intentionally added to the plating bath (and the plated layer) are shown as blank columns in table 1.
[ TABLE 1 ]
By the above-mentioned method, the method,for the interface Mg in various hot dip plated steel sheets obtained in the above steps 2 The ratio of the total interfacial contact length of the Si phase to the visual field, and the Mg content of the coarse interface 2 Number density of Si phase and interface Mg 2 The maximum value of the interfacial contact length of the Si phase was measured. The measurement results are shown in Table 2. Further, corrosion resistance and workability of each hot-dip plated steel sheet obtained in the above-described steps were also evaluated.
The corrosion resistance was evaluated in the following manner: a hot-dip plated steel sheet was cut into a shape of 150mm in the vertical direction and 70mm in the horizontal direction, subjected to 30 cycles of corrosion promotion test CCT in accordance with JASO-M609, and then the amount of corrosion loss was measured. The judgment criteria are as follows, and the judgment results are shown in table 2. The hot-dip plated steel sheet judged as "B" or "A" was judged as a high corrosion-resistant hot-dip plated steel sheet.
A: corrosion loss less than 30g/m 2 。
B: the corrosion loss was 30g/m 2 More than and less than 50g/m 2 。
C: the corrosion loss was 50g/m 2 Above and below 70g/m 2 。
D: the corrosion loss was 70g/m 2 The above.
The processability was evaluated in the following manner: a bending test was performed in which the hot-dip plated steel sheet was bent at a bending angle of 180 °, and a tape (tape) peeling test was performed on the bent portion. Tape peeling test in conformity with JIS H8504: 1999 "adhesion test method for plating". When the hot-dip plated steel sheet is bent, the interval inside the bend is set to 1 sheet (i.e., about 0.8 mm). The determination criteria are as follows, and the determination results are shown in table 2. The hot dip plated steel sheet judged to be "B" or "a" is judged to be a hot dip plated steel sheet having excellent plating adhesion.
A: no plating layer is stripped.
B: the stripping area rate of the plating layer is less than 1 percent.
C: the stripping area rate of the plating layer is more than 1 percent and less than 10 percent.
D: the stripping area rate of the plating layer is more than 10 percent.
In table 2, underlines are marked for values outside the scope of the invention.
[ TABLE 2 ]
In comparative example 16, the surfactant concentration of the alkali degreasing solution was insufficient. In comparative example 16, the interface Mg existing at the interface between the base steel sheet and the hot-dip plated layer 2 The proportion of the total of the interfacial contact lengths of the Si phases occupying the visual field is excessive, and the interfacial Mg having an equivalent circle diameter of 30 μm or more, which is present at the interface between the base steel sheet and the hot-dip coating layer 2 Number density of Si phase (coarse interface Mg) measured in plan view 2 Number density of Si phases) is excessive, and workability is impaired.
In comparative example 17, the surfactant concentration of the alkali degreasing solution was excessive. In comparative example 17, the interface Mg existing at the interface between the base steel sheet and the hot-dip plated layer 2 The total of the interfacial contact lengths of the Si phases occupies an excessive proportion of the visual field, and the workability is impaired.
In comparative example 18, the surfactant concentration of the alkali degreasing solution was excessive, and the pH of the washing water used for washing the base steel sheet after alkali degreasing was insufficient. In comparative example 18, the interface Mg existing at the interface between the base steel sheet and the hot-dip plated layer 2 The ratio of the total interfacial contact length of the Si phase to the visual field is excessive, and Mg is coarse in the coarse interface 2 The number density of Si phases becomes excessive, and the workability is impaired.
In comparative example 19, the amounts of Al and Mn contained in the plating layer were insufficient. In comparative example 19, both corrosion resistance and workability were impaired.
In comparative example 20, the pH of the washing water used for washing the base steel sheet after the alkali degreasing was insufficient. In comparative example 20, the interface Mg existing at the interface between the base steel sheet and the hot-dip plated layer 2 The ratio of the total interfacial contact length of the Si phase to the visual field is excessive, and Mg is coarse in the coarse interface 2 The number density of the Si phase is excessive,the workability is impaired.
In comparative example 21, the pH of the washing water used for washing the base steel sheet after the alkali degreasing was insufficient in a part of the washing step. In comparative example 21, mg is present in the coarse interface 2 The number density of Si phases becomes excessive, and the workability is impaired.
On the other hand, in the invention examples of nos. 1 to 15, since degreasing and washing with water were performed under appropriate conditions, the interface Mg existing at the interface between the base steel sheet and the hot-dip plated layer, measured in a vertical cross-sectional view of 10mm length, was measured 2 The total of the interfacial contact lengths of the Si phases is 20% or less of the visual field, and the interfacial Mg having an equivalent circle diameter of 30 [ mu ] m or more is present at the interface between the base steel sheet and the hot-dip coating layer 2 The number density of the Si phase measured in a plan view is set to 10 pieces/mm 2 The following. The inventive examples nos. 1 to 15 were excellent in both corrosion resistance and processed part plating adhesion.
Industrial applicability
According to the present invention, it is possible to provide a high corrosion-resistant hot-dip plated steel sheet having excellent working portion plating adhesion and a method for producing the same. Therefore, the present invention has high industrial applicability.
Description of the reference numerals
1. Hot-dip coated steel sheet
11. Base steel plate
12. Hot dip coating
13. Interface Mg 2 Phase of Si
Interface Mg in depth direction of A coating 2 Maximum length of Si phase
Interface Mg of B interface horizontal direction 2 Maximum length of Si phase
L1-L3 interface Mg 2 Interfacial contact length of Si phase
Claims (8)
1. A hot-dip coated steel sheet comprising:
base steel sheet, and
hot dip coating;
the chemical components of the hot dip coating comprise Al:4.0 to 22 mass%, mg:1 to 10 mass%, and Si: 0.0001-2 mass%, the remainder being made up of Zn and impurities;
the sum of the adhesion amount of the hot dip coating on the two surfaces is 40-600 g/m 2 ；
An interface Mg existing at an interface between the base steel sheet and the hot-dip coating layer, measured in a vertical cross-sectional view of 10mm in length 2 The total interfacial contact length of the Si phase is 20% or less of the visual field;
the interface Mg having an equivalent circle diameter of 30 [ mu ] m or more, which is present at the interface between the base steel sheet and the hot-dip coating layer 2 The number density of the Si phase measured in a plan view is 10 pieces/mm 2 The following.
2. The hot dip plated steel sheet according to claim 1,
the interface Mg measured in the vertical cross-section field of 10mm length 2 The maximum value of the interfacial contact length of the Si phase is 50 [ mu ] m or less.
3. The hot dip plated steel sheet according to claim 1 or 2,
the interface Mg 2 The ratio b/a of the length a of the Si phase in the depth direction of the plating layer to the length b of the interface in the horizontal direction is 0.1 to 10 in the longitudinal field of view of 10mm in the vertical cross section.
4. The hot-dip coated steel sheet according to any one of claims 1 to 3,
the chemical component of the hot-dip plating layer is 0.001 to 2 mass% in total, in place of part of the Zn, of at least one selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf.
5. The hot dip coated steel sheet according to any one of claims 1 to 4,
the chemical component of the hot-dip coating layer is substituted for a part of the Zn, and contains 0.001 to 2 mass% in total of 1 or more selected from the group consisting of Ni, ti, zr, and Sr.
6. A method of manufacturing a hot dip coated steel sheet as set forth in any one of claims 1 to 5, comprising:
a step of alkali degreasing the base steel sheet with an alkali degreasing solution containing 0.5 to 5.0 mass% of a surfactant,
washing the base steel sheet after the alkali degreasing,
a step of annealing the base steel sheet after the water washing, and
immersing the annealed base steel sheet in a solution containing Al:4.0 to 22 mass%, mg:1 to 10 mass%, si:0.0001 to 2 mass% and a hot-dip plating bath composed of Zn and impurities for the remainder to form a hot-dip plating layer;
in the above washing, the ph of the washing water is set to be not less than 8.7 and not more than 12 at all times.
7. The method of manufacturing a hot dip coated steel sheet according to claim 6,
the hot-dip plating bath contains, in place of a part of Zn, 0.001 to 2 mass% in total of 1 or more selected from the group consisting of Fe, sb, pb, sn, ca, co, mn, P, B, bi, cr, group 3 elements, REM, and Hf.
8. The method of manufacturing a hot dip coated steel sheet according to claim 6 or 7,
the hot-dip plating bath contains 0.001 to 2% by mass in total of 1 or more selected from the group consisting of Ni, ti, zr, and Sr, in place of part of the Zn.
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- 2021-04-20 JP JP2022504604A patent/JP7127750B2/en active Active
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| CN115427602B (en) | 2024-05-24 |
| KR20220152301A (en) | 2022-11-15 |
| JP7127750B2 (en) | 2022-08-30 |
| KR102590172B1 (en) | 2023-10-19 |
| JPWO2021215421A1 (en) | 2021-10-28 |
| WO2021215421A1 (en) | 2021-10-28 |
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