JP2010242188A - Galvanized steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a galvanized steel sheet having excellent press-forming property. <P>SOLUTION: The steel sheet has a coating having an average film thickness of 10 nm to 2,000 nm and containing crystalline lamellar material on the surface of the sheet. The crystalline lamellar material is, for example, a lamellar double hydroxide expressed by [M<SP>2+</SP><SB>1-x</SB>M<SP>3+</SP><SB>x</SB>(OH)<SB>2</SB>][A<SP>n-</SP>]<SB>x/n</SB>zH<SB>2</SB>O, wherein preferably M<SP>2+</SP>represents at least one of Mg<SP>2+</SP>, Ca<SP>2+</SP>, Fe<SP>2+</SP>, Ni<SP>2+</SP>and Zn<SP>2+</SP>; M<SP>3+</SP>represents at least one of Al<SP>3+</SP>, Fe<SP>3+</SP>and Cr<SP>3+</SP>; and A<SP>n-</SP>represents at least one of CO<SB>3</SB><SP>2-</SP>, Cl<SP>-</SP>and (SO<SB>4</SB>)<SP>2-</SP>. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a galvanized steel sheet having a small sliding resistance during press forming and having excellent press formability.

Zinc-based galvanized steel sheets are widely used in a wide range of fields centering on automobile body applications, and in such applications, they are subjected to press forming and used. However, galvanized steel sheets have the disadvantage that they are inferior in press formability compared to cold rolled steel sheets. This is because the sliding resistance of the surface-treated steel sheet in the press die is larger than that of the cold-rolled steel sheet. That is, it becomes difficult for the surface-treated steel sheet to flow into the press mold at a portion where the sliding resistance between the mold and the bead is large, and the steel sheet is easily broken. Especially in the case of pure galvanized steel sheets, there is a phenomenon in which sliding resistance increases due to the adhesion of the plating to the mold (mold galling), and cracking occurs during the continuous press forming, which increases automobile productivity. Serious adverse effects. Furthermore, from the viewpoint of strengthening CO ₂ emission regulations in recent years, the usage ratio of high-strength steel sheets tends to increase for the purpose of reducing vehicle body weight. When a high-strength steel plate is used, the surface pressure during press forming increases, and plating adhesion to the mold becomes a more serious problem.

  In addition to this, as a method for improving the press formability when using a galvanized steel sheet, a method of applying a high-viscosity lubricating oil is widely used. However, in this method, a coating defect due to poor degreasing occurs in the coating process due to the high viscosity of the lubricating oil. In addition, there is a problem that the press performance becomes unstable due to oil shortage during pressing. Accordingly, there is a strong demand for improving the press formability of the galvanized steel sheet itself.

  As a method for solving the above problem, Patent Document 1 and Patent Document 2 describe that an oxidation mainly composed of zinc O is performed by subjecting the surface of a galvanized steel sheet to electrolytic treatment, immersion treatment, coating oxidation treatment, or heat treatment. A technique for improving weldability and workability by forming a film is disclosed.

  Patent Document 3 discloses that P oxidation is performed by immersing a plated steel sheet in an aqueous solution containing 5 to 60 g / l of sodium phosphate and having a pH of 2 to 6, performing electrolytic treatment, or applying the aqueous solution. A technique for improving press moldability and chemical conversion property by forming an oxide film mainly composed of an object is disclosed.

  Patent Document 4 discloses a technique for improving press formability and chemical conversion treatment by generating Ni oxide by electrolytic treatment, immersion treatment, coating oxidation treatment, or heat treatment on the surface of a galvanized steel sheet. Yes.

JP-A-53-60332 Japanese Patent Laid-Open No. 2-190483 JP-A-4-88196 Japanese Patent Laid-Open No. 3-191093

  However, the above prior art is effective for a galvanized steel sheet having a relatively low strength, which is often used for an automobile outer plate, but in the case of a high strength galvanized steel sheet in which the surface pressure during press forming increases. However, the effect of improving the press formability cannot always be obtained sufficiently.

  An object of the present invention is to improve the above-mentioned problems and to provide a zinc-based plated steel sheet having excellent press formability even in difficult-to-form materials such as a high-strength galvanized steel sheet that increases the surface pressure during press forming. To do.

In the conventional film, the frictional resistance is reduced by suppressing the contact between the galvanized layer and the mold. However, under high surface pressure conditions in press forming of high-strength steel plates, the amount of wear of the film increases, so that a sufficient effect cannot be obtained if the sliding distance exceeds a certain amount.
The inventors of the present invention made further studies to solve the above problems. As a result, in order to dramatically improve the slidability, it has been found that it is effective to include a crystalline layered material in the surface layer of a zinc-based plated steel sheet and form a film containing the crystalline layered material. It was.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] A zinc-based galvanized steel sheet having a film containing a crystalline layered material on a surface layer, wherein the average film thickness of the film is 10 nm to 2000 nm.
[2] In the above [1], the crystalline layered product is a layered double hydroxide represented by [M 2 ⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ⁿ⁻ ] _{x / n} · zH ₂ O The M ²⁺ is Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ni ²⁺ , zinc ²⁺ , Pb ²⁺ , Sn ²⁺ , and the M ³⁺ is ^{Al 3+, Fe 3+, Cr 3+} , and a 3 / 4Zr ^4+, 1 or more kinds of Mo ^3+, wherein a ^n- is _{^{OH -, F -, CO 3}} 2-, Cl - _{^{, Br -, (C 2 O}} 4) 2-, I -, (NO 3) -, (SO 4) 2-, (BrO 3) -, (IO 3) -, (V 10 O 28) 6-, (Si ₂ O ₅ ) ^2- , (ClO ₄ ) ⁻ , (CH ₃ COO) ⁻ , [C ₆ H ₄ (CO ₂ ) ₂ ] ^2- , (C ₆ H ₅ COO) ⁻ , [C ₈ H ₁₆ (CO ₂ ) ₂ ] ^2- , n (C ₈ H ₁₇ SO ₄ ) ^- , TPPC, n (C ₁₂ H ₂₅ SO ₄ ) ^- , n (C ₁₈ H ₃₇ SO ₄ ) ^- , SiO ₄ ^4- A galvanized steel sheet characterized by having two or more seeds.
[3] In the above [1], the crystalline layered product is a layered double hydroxide represented by [M ²⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ⁿ⁻ ] _{x / n} · zH ₂ O And the M ²⁺ is one or more of Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ni ²⁺ , and zinc ²⁺ , and the M ³⁺ is Al ³⁺ , Fe ³⁺ , is one or more of Cr ^3+, a ^{n-is _{OH -, CO 3 2-, Cl}} -, zinc, characterized in that it (SO ₄₎ ^2-one or more Plated steel sheet.

  In the present invention, for example, a steel sheet obtained by plating zinc on a steel sheet by various manufacturing methods such as a hot dipping method, an electroplating method, a vapor deposition method, and a thermal spraying method is collectively referred to as a zinc-based plated steel plate. Moreover, both the hot-dip galvanized steel sheet not subjected to the alloying treatment and the alloyed hot-dip galvanized steel sheet subjected to the alloying treatment are included in the zinc-based plated steel sheet.

  According to the present invention, even in a high-strength galvanized steel sheet in which the surface pressure at the time of press forming increases, the sliding resistance at the cracking risk portion at the time of press forming is small, and the surface pressure is high and the plating adheres to the mold. A zinc-based galvanized steel sheet having excellent press formability can be obtained even in assumed parts.

Schematic front view showing the dynamic friction coefficient measuring device Schematic perspective view showing bead shape and dimensions in FIG. Schematic perspective view showing bead shape and dimensions in FIG.

  In the conventional film, the frictional resistance is reduced by suppressing the contact between the galvanized layer and the mold. However, under the surface pressure conditions in press forming of high-strength steel sheets, the amount of wear of the film increases, so that a sufficient effect cannot be obtained if the sliding distance exceeds a certain amount.

Therefore, in the present invention, the surface layer of the galvanized steel sheet has a crystalline layered film.
Although the lubrication mechanism of the crystalline layered film is not clear, it can be considered as follows. During sliding, a shear stress is generated on the surface due to the adhesive force between the mold and the plating. The presence of the crystalline layered material between the plating and the mold absorbs the shear deformation stress generated on the surface due to slip deformation of the crystalline layered material. Even after the crystalline layered material is worn out from the zinc-based plating surface layer, it exhibits the effect of adhering to the mold and reducing the frictional resistance. Therefore, the crystalline layered material has a sufficient effect even under high surface pressure conditions assuming a high-strength steel sheet. It becomes possible. As described above, it is the most important requirement in the present invention to have a film containing a crystalline layered material on the surface layer of a galvanized steel sheet.
The thickness of the crystalline layered film is 10 nm or more and 2000 nm or less on average as the thickness when observed by SEM from the cross section. If the average is less than 10 nm, it is difficult to obtain a sufficient sliding property improvement effect. On the other hand, when it exceeds 2000 nm on average, there is a concern that spot weldability, which is important in automobile production, is reduced.
The thickness of the crystalline layered film is measured from the result of observing the cross section processed with FIB with an ultra-low acceleration SEM, and the identification of the crystalline structure as to whether the crystalline layered film is crystalline is a thin film X-ray diffraction Can be done.
In the present invention, the crystalline layered material is a crystal in which a plate-like covalently bonded crystal is laminated with relatively weak bonds such as intermolecular force, hydrogen bond, electrostatic energy, etc. in the unit crystal lattice. is there. Among them, the layered double hydroxide whose structure can be represented by [M ²⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ⁿ⁻ ] _{x / n} · zH ₂ O is a positively charged plate It has a layered crystal structure because negatively charged anions are bonded to each other by electrostatic energy in order to maintain electrical balance with the divalent and trivalent metal hydroxides, and are laminated in layers. It is preferable to be used as an active layered product.
[M ²⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ^n- ] The layered double hydroxide represented by _{x / n} · zH ₂ O can be identified by X-ray diffraction. It is known that a substance that can be represented by the above formula becomes a layered crystal.
[M ²⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ^n- ] The crystalline material represented by _{x / n} · zH ₂ O is layered because of the positively charged plate-like divalent property. This is because negatively charged anions are bonded to the trivalent metal hydroxide by electrostatic energy in order to maintain an electrical balance and are laminated in layers.

M ²⁺ is preferably one or more of Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ni ²⁺ , zinc ²⁺ , Pb ²⁺ , and Sn ²⁺ . Among them, Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ni ²⁺ , and zinc ²⁺ have been confirmed as natural or artificially generated layered double hydroxide species and are stable as layered double hydroxides. It is more preferable because it can exist.

M ³⁺ is preferably one or more of Al ³⁺ , Fe ³⁺ , Cr ³⁺ , 3 / 4Zr ⁴⁺ and Mo ³⁺ . Among them, Al ³⁺ , Fe ³⁺ , and Cr ³⁺ have been confirmed as layered double hydroxide species generated naturally or artificially and can exist stably as layered double hydroxides. More preferable.

A The ^{n-, OH -, F -,} CO 3 2-, Cl -, Br -, (C 2 O 4) 2-, I -, (NO 3) -, (SO 4) 2-, (BrO ₃ ) ^- , (IO ₃ ) ^- , (V ₁₀ O ₂₈ ) ^6- , (Si ₂ O ₅ ) ^2- , (ClO ₄ ) ^- , (CH ₃ COO) ^- , [C ₆ H ₄ (CO ₂ ) ₂ ] ^2- , (C ₆ H ₅ COO) ^- , [C ₈ H ₁₆ (CO ₂ ) ₂ ] ^2- , n (C ₈ H ₁₇ SO ₄ ) ^- , TPPC, n (C ₁₂ H ₂₅ SO ₄ ) _{^{-, n (C 18 H 37}} SO 4) -, SiO 4 4- 1 or two or more are preferred. These have been confirmed to be incorporated as interlayer anions of the layered double hydroxide species, and can exist as layered double hydroxides. Among _{^{them, OH -, CO 3 2-,}} Cl -, (SO 4) 2- is easily capture an interlayer anions as compared to the time of forming the zinc-based plated steel sheet with other anions of the layered double hydroxide species Since the film can be formed in a short time, it can be more suitably used as an anion.
Next, a method for producing the crystalline crystalline layered material on the zinc-based plated steel sheet will be described.
Here, a method using an electrochemical reaction is taken as an example of a method of generating a layered double hydroxide, which is a kind of the crystalline layered material, on a zinc-based plated steel sheet. And any one or more divalent cations (M ^2+), and any one or more trivalent cation (M ^3+), A ^n- = any one of (inorganic anion or an organic anion) 1 In a solution having a pH of 0.5 to 7.0 containing more than one kind of anion, a current of 0.01 to 100 A / dm ² is passed using a galvanized steel sheet as a cathode.

Although the formation mechanism of this layered substance is not clear, it can be considered as follows. When an alloyed hot-dip galvanized steel sheet is used as a cathode, current flows through the steel sheet, causing reduction of hydrogen ions or decomposition of dissolved oxygen, resulting in an increase in the pH of the steel sheet surface.
Here, the divalent cation and the trivalent cation existing in the solution are formed as a hydroxide in a region where the pH of the steel sheet surface is increased in a colloidal form. OH wherein, in the liquid _{^{-, F -, CO 3 2-}} , Cl -, Br -, (C 2 O 4) 2-, I -, (NO 3) -, (SO 4) 2-, (BrO ₃ ) ^- , (IO ₃ ) ^- , (V ₁₀ O ₂₈ ) ^6- , (Si ₂ O ₅ ) ^2- , (ClO ₄ ) ^- , (CH ₃ COO) ^- , [C ₆ H ₄ (CO ₂ ) ₂ ] ^2- , (C ₆ H ₅ COO) ^- , [C ₈ H ₁₆ (CO ₂ ) ₂ ] ^2- , n (C ₈ H ₁₇ SO ₄ ) ^- , TPPC, n (C ₁₂ H ₂₅ SO ₄ ) ^When one or more specific anions of-, n (C ₁₈ H ₃₇ SO ₄ ) ^- , and SiO ₄ ^4- are present, the metal hydroxide precipitates on the surface of the steel sheet as a layered double hydroxide.

  Incidentally, regarding the production of the hot dip galvanized steel sheet and alloyed hot dip galvanized steel sheet according to the present invention, it is necessary that Al is added to the plating bath, but the additive element components other than Al are not particularly limited. . That is, even if Pb, Sb, Si, Sn, Mg, Mn, Ni, Ti, Li, etc. are contained or added in addition to Al, the effect of the present invention is not impaired.

  Furthermore, even if N, Pb, Na, Mn, Ba, Sr, Si, etc. are taken into the coating layer due to impurities contained in the processing solution used for the film forming process, the effect of the present invention is impaired. It is not a thing.

  Next, the present invention will be described in more detail with reference to examples.

An alloyed hot-dip galvanized film was formed on a cold-rolled steel sheet having a thickness of 0.7 mm by a conventional method, and further temper rolled. Similarly, a hot dip galvanized film and an electrogalvanized film were formed by a conventional method. Subsequently, the layered double hydroxide formation treatment included magnesium nitrate hexahydrate: 113 g / L, aluminum nitrate nonahydrate: 83 g / L, sodium carbonate decahydrate: 31 g / L, and nitric acid. The steel plate was immersed in a solution adjusted to pH 5.0 by using the steel plate, and a current density of 1 A / dm ² was applied for ² to 300 seconds using the steel plate as a cathode. Next, after sufficiently washing with water, it was dried.

While measuring the film thickness of the layered double hydroxide film | membrane of the alloyed hot-dip galvanized steel plate obtained by the above, a hot-dip galvanized steel plate, and an electrogalvanized steel plate, the layered double hydroxide was identified. In addition, as a method for evaluating the press formability, the friction coefficient was measured and the mold caulking property was evaluated to evaluate the sliding characteristics. The method for measuring the thickness of the layered double hydroxide layer on the plating surface layer, the method for identifying the layered double hydroxide film, and the method for measuring the sliding property are as follows.
1) Measurement of layered double hydroxide film thickness
The cross section of the film was sputtered to 45 ° using FIB, and the average value obtained by measuring any 10 points from the result of observation from the cross section with an ultra-low acceleration SEM was taken as the film thickness of the film.
2) Identification method of layered double hydroxide The presence of crystalline layered double hydroxide was confirmed by thin film X-ray diffraction. The layered double hydroxide was identified by checking the peak obtained by the thin film method with Cu-Kα ray and setting the incident angle to 0.5 ° with the ICDD card. Matched cards were:
Magnesium Aluminum Hydroxide Carbonate Hydrate
ICDD Cart Reference Coat: 01-089-0460
[Mg _0.667 Al _0.333 (OH) ₂ ] [CO ₃ ^2- ] _0.167・ 0.5H ₂ O
3) Method for measuring friction coefficient In order to evaluate press formability (particularly, formability at the drawing / inflow portion), the dynamic friction coefficient of each specimen was measured as follows. FIG. 1 is a schematic front view showing a friction coefficient measuring apparatus. As shown in the figure, a friction coefficient measuring sample 1 collected from a test material is fixed to a sample table 2, and the sample table 2 is fixed to the upper surface of a slide table 3 that can move horizontally. On the lower surface of the slide table 3, there is provided a slide table support base 5 having a roller 4 in contact with the slide table 3 and capable of moving up and down, and by pushing this up, a pressing load N to the friction coefficient measuring sample 1 by the bead 6 is measured. A first load cell 7 is attached to the slide table support 5. A second load cell 8 is attached to one end portion of the slide table 3 in order to measure the sliding resistance force F for moving the slide table 3 in the horizontal direction with the pressing force applied. In addition, the cleaning oil Preton R352L for press made by Sugimura Chemical Co., Ltd. was applied to the surface of the friction coefficient measurement sample 1 as a lubricant, and the test was performed.
FIG. 2 is a schematic perspective view showing the shape and dimensions of the bead used (bead shape 1). The bead 6 slides with its lower surface pressed against the surface of the friction coefficient measurement sample 1. The shape of the bead 6 shown in FIG. 4 is 10 mm wide, 12 mm long in the sliding direction of the sample, and the lower part of both ends of the sliding direction is a curved surface with a curvature of 4.5 mmR. It has a 3mm long plane.
FIG. 3 is a schematic perspective view showing the shape and dimensions of the beads used (bead shape 2). The bead 6 slides with its lower surface pressed against the surface of the friction coefficient measurement sample 1. The bead 6 shown in FIG. 4 has a width of 10 mm, a length of 59 mm in the sliding direction of the sample, and a lower portion at both ends of the sliding direction is formed by a curved surface having a curvature of 4.5 mmR. It has a flat surface with a length of 50 mm.
The friction coefficient was measured under three conditions of a pressing load N of 400, 1200, and 1600 kgf at room temperature (25 ° C.) so as to obtain a surface pressure assuming press forming of a high-strength steel plate. The sample drawing speed (the horizontal movement speed of the slide table 3) is 100 cm / min and 20 cm / min. Under these conditions, the pressing load N and the pulling load F were measured, and the coefficient of friction μ between the test material and the bead was calculated by the formula: μ = F / N.

The combinations of bead shape, pressing load conditions, and drawing speed are as follows.
Condition 1: Bead shape 1 Press load 400kgf Pull-out speed 100cm / min
Condition 2: Bead shape 1 Pressing load 1200kgf Extraction speed 100cm / min
Condition 3: Bead shape 1 Pressing load 1600kgf Pull-out speed 100cm / min
Condition 4: Bead shape 2 Pressing load 400kgf Extraction speed 20cm / min
4) Measurement method of mold caulking property In addition to the dynamic friction coefficient, in pure zinc-based plated steel sheets, there is a problem of mold galling that causes plating to adhere to the mold and increase the sliding resistance at sites where the sliding distance is long. Therefore, using the friction coefficient measuring device shown in Fig. 1, the sliding test was repeated 50 times, and the number of repetitions where the friction coefficient increased by 0.01 or more was used as the number of mold galling occurrences, and the mold caulking property was evaluated. did. Here, when no increase in the coefficient of friction was observed even after the 50th sliding test was performed, it was set to 50 times or more. The test conditions were the same as those in the above conditions 1 to 3 so that the surface pressure was assumed to be press-forming of a high-strength steel sheet in the same manner as in the above-described 3) friction coefficient measurement method.

  The test results obtained above are shown in Table 1 together with the conditions.

From the test results shown in Table 1, the following matters were clarified.
No. 1 is a comparative example of an galvannealed steel sheet that has not been subjected to film formation. The friction coefficient is a high value.
No. 2 is a comparative example of an alloyed hot-dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient.
Nos. 3 to 6 are alloyed hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently lower than the comparative examples No. 1 and 2.
No. 7 is a comparative example of a hot-dip galvanized steel sheet that has not been subjected to film formation. The coefficient of friction is a high value, and the coefficient of friction increases with a small number of repetitions even in mold caulking.
No. 8 is a comparative example of a hot dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the friction coefficient is lower than that of No7 where no film formation treatment is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 9 to 12 are hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently lower than the comparative examples of Nos. 7 and 8. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 13 is a comparative example of an electrogalvanized steel sheet that has not been subjected to film formation. The coefficient of friction is a high value, and the coefficient of friction increases with a small number of repetitions even in mold caulking.
No. 14 is a comparative example of an electrogalvanized steel sheet subjected to film formation. Since the film thickness is insufficient, the friction coefficient is lower than that of No13 where no film formation treatment is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 15 to 18 are electrogalvanized steel sheets subjected to film forming treatment, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently lower than the comparative examples No. 13 and 14. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.

A hot-dip galvanized film was formed on a cold-rolled steel sheet having a thickness of 0.7 mm by a conventional method, and further temper rolled. Subsequently, as a layered double hydroxide formation treatment, the steel sheet was immersed in a solution containing the composition shown in Table 2 and adjusted to pH 5.0 using nitric acid, and the steel sheet was used as a cathode at a current density of 1 A / dm ^{2 from 2} to 2 Energized for 300 seconds. Next, after sufficiently washing with water, it was dried.

While measuring the film thickness of the layered double hydroxide film of the plating surface layer on the hot dip galvanized steel sheet obtained as described above, the layered double hydroxide was identified. In addition, as a method for evaluating the press formability, the friction coefficient was measured and the mold caulking property was evaluated to evaluate the sliding characteristics. The method for measuring the thickness of the layered double hydroxide layer on the plating surface layer, the method for identifying the layered double hydroxide film, and the evaluation method for the method for measuring the sliding property are the same as in Example 1. The matched ICDD card is as follows.
A) Zinc Aluminum Carbonate Hydroxide Hydrate
ICDD Cart Reference Coat: 00-048-1021
[Zn _0.71 Al _0.29 (OH) ₂ ] [CO ₃ ^2- ] _0.145・ H ₂ O
B) Iron Carbonate Hydroxide Hydrate
ICDD cart reference coat: 00-050-1380
[Fe _0.67 Fe _0.33 (OH) ₂ ] [CO ₃ ^2- ] _0.145・ 0.33H ₂ O
C) Iron Nickel Sulfate Hydroxide Hydrate
ICDD Cart Reference Coat: 00-042-0573
[Ni _0.75 Fe _0.25 (OH) ₂ ] [SO ₄ ^2- ] _0.125・ 0.5H ₂ O
D) Magnesium Aluminum Hydroxide Hydrate
ICDD Cart Reference Court: 00-038-0478
_{[Mg 0.75 Al 0.25 (OH)} 2] [OH -] 0.25 · 0.5H 2 O
E) Magnesium Iron Oxide Chloride Hydroxide Hydrate
ICDD Cart Reference Coat: 00-020-0500
_{[Mg 0.75 Fe 0.25 (OH)} 2] [Cl -] 0.25 · 0.5H 2 O
F) Calcium Aluminum Hydroxide Chloride Hydrate
ICDD Cart Reference Coat: 00-035-0105
_{[Ca 0.67 Al 0.33 (OH)} 2] [Cl -] 0.33 · 0.67H 2 O
G) Magnesium Chromium Carbonate Hydroxide Hydrate
ICDD Cart Reference Coat: 00-045-1475
[Mg _0.67 Cr _0.33 (OH) ₂ ] [CO ₃ ^2- ] _0.157・ 0.5H ₂ O
H) Nickel Aluminum Oxide Carbonate Hydroxide Hydrate
ICDD Cart Reference Coat: 00-051-1527
[Fe _0.67 Al _0.33 (OH) ₂ ] [CO ₃ ^2- ] _0.157・ 0.5H ₂ O
I) Nickel Aluminum Oxide Carbonate Hydroxide Hydrate
ICDD Cart Reference Coat: 00-015-0087
_{[Ni 0.67 Al 0.33 (OH)} 2] [CO 3 2-, OH -] 0.157 · 0.5H 2 O
The test results obtained above are shown in Table 2 together with the conditions.

From the test results shown in Table 2, the following matters became clear.
No19 is a comparative example of a hot-dip galvanized steel sheet that has not been subjected to film formation. The coefficient of friction is a high value, and the coefficient of friction increases with a small number of repetitions even in mold caulking.
No. 20 is a comparative example of a hot dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the friction coefficient is lower than that of No19 where no film formation treatment is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 21 to 24 are hot-dip galvanized steel sheets subjected to film formation, and are examples of the present invention in which the film thickness is within the scope of the present invention. The coefficient of friction is sufficiently lower than the comparative examples of No19 and 20. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 25 is a comparative example of a hot dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 26 to 29 are hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently reduced compared to the No25 comparative example. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 30 is a comparative example of a hot-dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 31 to 34 are hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently lower than the comparative example of No30. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 35 is a comparative example of a hot dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 36 to 39 are hot-dip galvanized steel sheets subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently low compared to the comparative example of No35. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 40 is a comparative example of a hot-dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 41 to 44 are hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently reduced as compared with the comparative example of No. 40 where no film forming process is performed. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 45 is a comparative example of a hot dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 46 to 49 are hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently reduced compared to the No45 comparative example. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 50 is a comparative example of a hot dip galvanized steel sheet subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 51 to 54 are hot-dip galvanized steel sheets subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently lower than the comparative example of No50. Further, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 55 is a comparative example of a hot dip galvanized steel sheet subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film forming process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 56 to 59 are hot-dip galvanized steel sheets subjected to film forming treatment, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently lower than that of the No55 comparative example. Also, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.
No. 60 is a comparative example of a hot dip galvanized steel sheet that has been subjected to film formation. Since the film thickness is insufficient, the coefficient of friction is lower than that of No1 where no film formation process is performed, but the effect is not sufficient. In addition, the mold caulking property tends to increase the number of repetitions in which the friction coefficient increases, but the effect is not sufficient.
Nos. 61 to 64 are hot-dip galvanized steel sheets that have been subjected to film formation, and are examples of the present invention in which the film thickness is also within the scope of the present invention. The coefficient of friction is sufficiently reduced as compared with the comparative example of No60 where no film forming treatment is performed. Also, in the mold caulking property, the number of repetitions in which the friction coefficient increases tends to increase, and the effect is sufficient.

  Since the galvanized steel sheet of the present invention is excellent in press formability, it can be applied in a wide range of fields mainly for automobile body applications that require difficult-to-form materials.

DESCRIPTION OF SYMBOLS 1 Friction coefficient measurement sample 2 Sample stand 3 Slide table 4 Roller 5 Slide table support stand 6 Bead 7 1st load cell 8 2nd load cell 9 Rail N Pushing load F Sliding resistance force

Claims (3)

  A zinc-based plated steel sheet having a film containing a crystalline layered material on a surface layer, and an average film thickness of the film being 10 nm to 2000 nm. The crystalline layered product is a layered double hydroxide represented by [M ²⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ⁿ⁻ ] _{x / n} · zH ₂ O,
The M ²⁺ is one or more of Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ni ²⁺ , zinc ²⁺ , Pb ²⁺ , Sn ²⁺ ,
The M ³⁺ is Al ³⁺ , Fe ³⁺ , Cr ³⁺ , 3 / 4Zr ⁴⁺ , Mo ³⁺ or one or more of them,
The A ^n- may _{^{OH -, F -, CO 3}} 2-, Cl -, Br -, (C 2 O 4) 2-, I -, (NO 3) -, (SO 4) 2-, (BrO 3 ) ^- , (IO ₃ ) ^- , (V ₁₀ O ₂₈ ) ^6- , (Si ₂ O ₅ ) ^2- , (ClO ₄ ) ^- , (CH ₃ COO) ^- , [C ₆ H ₄ (CO ₂ ) ₂ ] ^2- , (C ₆ H ₅ COO) ^- , [C ₈ H ₁₆ (CO ₂ ) ₂ ] ^2- , n (C ₈ H ₁₇ SO ₄ ) ^- , TPPC, n (C ₁₂ H ₂₅ SO ₄ ) ^- 2. The galvanized steel sheet according to claim 1, wherein the galvanized steel sheet is one or more of n, (C ₁₈ H ₃₇ SO ₄ ) ⁻ and SiO ₄ ^4- . The crystalline layered product is a layered double hydroxide represented by [M ²⁺ _1-X M ³⁺ _X (OH) ₂ ] [A ⁿ⁻ ] _{x / n} · zH ₂ O,
The M ²⁺ is one or more of Mg ²⁺ , Ca ²⁺ , Fe ²⁺ , Ni ²⁺ , and zinc ²⁺ ;
M ³⁺ is one or more of Al ³⁺ , Fe ³⁺ , Cr ³⁺ ,
A ^n- is _{^{OH -, CO 3 2-, Cl}} -, (SO 4) galvanized steel sheet according to claim 1, characterized in that ^2-one or more.

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