Specification
Title of Invention : Hot dip plated steel sheet
Technical field
[0001]
The present invention relates to hot-dip plated steel sheets.
This application claims priority based on Japanese Patent Application Nos. 2019-216681, 2019-216682, 2019-216683 and 2019-216684 filed in Japan on November 29, 2019. , the contents of which are hereby incorporated by reference.
Background technology
[0002]
Hot-dip plated steel sheets have excellent corrosion resistance, and among them, Zn-Al-Mg-based hot-dip plated steel sheets have particularly excellent corrosion resistance. Such hot-dip plated steel sheets are widely used in various manufacturing industries such as building materials, home electric appliances, and automobile fields, and the amount of use thereof is increasing in recent years.
[0003]
By the way, for the purpose of showing letters, patterns, design drawings, etc. on the surface of the hot-dip plated steel sheet, letters, patterns, designs, etc. It may appear on the surface of the hot-dip plating layer.
[0004]
However, when processes such as printing and painting are performed on the hot-dip plating layer, there is a problem that the cost and time for applying characters and designs will increase. Furthermore, when printing or painting characters or designs on the surface of the plating layer, not only does the metallic luster appearance that is highly popular with consumers be lost, but the coating itself deteriorates over time and the adhesion of the coating film deteriorates. Due to the problem of deterioration over time, the durability is poor, and characters and designs may disappear over time. In the case of stamping ink to reveal characters, designs, etc. on the surface of the plated layer, the cost and time can be kept relatively low, but there is a concern that the corrosion resistance of the hot-dip plated layer is lowered by the ink. Furthermore, when the design is created by grinding the hot-dip plating layer, the durability of the design is excellent, but the thickness of the hot-dip plating layer at the grinding point is greatly reduced, which inevitably leads to a decrease in corrosion resistance and plating characteristics. is concerned.
[0005]
As shown in the following patent documents, various technical developments have been made for Zn-Al-Mg hot-dip plated steel sheets. Techniques for improving the durability of letters, designs, etc. on the surface of the plating layer. is not known.
[0006]
Regarding the Zn-Al-Mg hot-dip plated steel sheet, there are conventional technologies that aim to make the satin-like plating appearance seen in the Zn-Al-Mg hot-dip plated steel sheet more beautiful.
[0007]
For example, Patent Document 1 discloses a Zn-Al-Mg hot dip plated steel sheet having a fine texture and a satin-like appearance with many smooth glossy parts, that is, a large number of white parts per unit area, and a glossy A Zn-Al-Mg hot-dip plated steel sheet having a good satin-like appearance in which the ratio of the area of ​​the part is large is described. In addition, Patent Document 1 describes that the unfavorable pear-skin state is a state in which irregular white portions and circular glossy portions are intermingled and scattered on the surface, presenting a surface appearance. there is
[0008]
In addition, in Patent Document 2, in the thickness direction cross section of the plating layer, the portion where Al crystals are absent between the interface between the plating layer and the base iron and the plating surface layer is 10% of the width direction length of the cross section. A Zn-Al-Mg-based plated steel sheet with an improved plating appearance is described.
[0009]
Furthermore, in Patent Document 3, the center line average roughness Ra of the surface of the plated steel sheet is 0.5 to 1.5 μm, and the PPI (1.27 μm or more included per inch (2.54 cm)) number of peaks) is 150 to 300, and Pc (the number of peaks having a size of 0.5 μm or more contained per 1 cm) is Pc≧PPI/2.54+10 and has excellent formability. Have been described.
Furthermore, in Patent Document 4, by refining the ternary eutectic structure of Al/MgZn2/Zn, the glossiness of the coating layer is increased as a whole, and the appearance uniformity is improved. High corrosion resistance hot-dip galvanized steel sheet is described.
[0010]
However, no technology has been known in the past to improve durability and prevent deterioration in corrosion resistance when letters and the like are displayed on the surface of the plating layer.
prior art documents
patent literature
[0011]
Patent Document 1: Japanese Patent No. 5043234
Patent Document 2: Japanese Patent No. 5141899
Patent Document 3: Japanese Patent No. 3600804
Patent Document 4: International Publication No. 2013/002358
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0012]
The present invention has been made in view of the above circumstances, and provides a hot-dip plated steel sheet that can display letters, designs, etc. on the surface of the plating layer, has excellent durability, and is also excellent in corrosion resistance. The challenge is to
Means to solve problems
[0013]
The gist of the present invention is as follows.
[1] A steel plate and a hot-dip coating layer formed on the surface of the steel plate,
The hot-dip plated layer contains, in average composition, Al: 0 to 90% by mass, Mg: 0 to 10% by mass, the balance being Zn and impurities,
The hot-dip plating layer includes a pattern portion arranged to have a predetermined shape and a non-pattern portion,
When the first and second areas are determined by any one of the following determination methods 1 to 5,
the pattern portion and the non-pattern portion are each composed of one or two of the first region and the second region,
A hot-dip plated steel sheet, wherein the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more.
[Determination method 1]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. A region is designated as A, and the L* value in each measurement region A is measured. Select arbitrarily 50 points from the obtained L* values, and use the average of the obtained L* values ​​for 50 points as the reference L* value. 1 region, and the region where the value is less than the reference L* value is defined as the second region.
[Determination method 2]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. The L* value is measured in each measurement area A, and the area where the L* value is 45 or more is defined as the first area, and the area where the L* value is less than 45 is defined as the second area.
[Determination method 3]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual grid lines. The region where the obtained Sa is 1 μm or more is defined as the first region, and the region where the obtained Sa is less than 1 μm is defined as the second region.
[Determination method 4]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm or 10 mm, and X-rays are incident on a plurality of regions partitioned by the virtual grid lines. The diffraction peak intensity I 0002 of the (0002) plane of the Zn phase and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I 0002/I 10-11) is oriented. rate. A region having an orientation ratio of 3.5 or more is defined as a first region, and a region having an orientation ratio of less than 3.5 is defined as a second region.
[Determination method 5]
A virtual grid line is drawn on the surface of the hot-dip plated layer at intervals of 1 mm, and then, for each of a plurality of regions partitioned by the virtual grid line, a circle S centered on the center of gravity G of each region is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the hot-dip plating layers included in the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin of the diameters R of the circles S in a plurality of regions is defined as a reference diameter Rave, and the region having the circle S with the diameter R less than the reference diameter Ra is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region.
[2] According to [1], the average composition of the hot-dip plating layer is 4 to 22% by mass of Al, 1 to 10% by mass of Mg, and the balance contains Zn and impurities. Hot dip plated steel sheet.
[3] The hot dip plated steel sheet according to [1] or [2], wherein the hot dip plated layer further contains Si: 0.0001 to 2% by mass in average composition.
[4] The hot-dip plated layer further has an average composition of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM , Hf, and C in a total content of 0.0001 to 2% by mass, the hot dip plated steel sheet according to any one of [1] to [3].
[5] The pattern portion is arranged in a shape that is a combination of any one of straight line portions, curved portions, dot portions, figures, numerals, symbols, patterns or characters, or a combination of two or more of these. The hot-dip plated steel sheet according to any one of [1] to [4], characterized in that
[6] The hot-dip plated steel sheet according to any one of [1] to [5], wherein the pattern portion is formed intentionally.
[7] The hot dip plated steel sheet according to any one of [1] to [6], characterized in that the total amount of the hot dip plated layer on both sides of the steel sheet is 30 to 600 g/m 2 .
[8] A steel plate and a hot-dip coating layer formed on the surface of the steel plate,
The hot-dip plated layer contains, in average composition, Al: 0 to 90% by mass, Mg: 0 to 10% by mass, the balance being Zn and impurities,
The hot-dip plating layer includes a pattern portion arranged to have a predetermined shape and a non-pattern portion,
The pattern portion and the non-pattern portion each include one or two of a first region and a second region determined by any of the following determination methods 1 to 5,
A hot-dip plated steel sheet, wherein the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more.
[Determination method 1]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. A region is designated as A, and the L* value in each measurement region A is measured. Select arbitrarily 50 points from the obtained L* values, and use the average of the obtained L* values ​​for 50 points as the reference L* value. 1 region, and the region where the value is less than the reference L* value is defined as the second region.
[Determination method 2]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. The L* value is measured in each measurement area A, and the area where the L* value is 45 or more is defined as the first area, and the area where the L* value is less than 45 is defined as the second area.
[Determination method 3]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual grid lines. The region where the obtained Sa is 1 μm or more is defined as the first region, and the region where the obtained Sa is less than 1 μm is defined as the second region.
[Determination method 4]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm or 10 mm, and X-rays are incident on a plurality of regions partitioned by the virtual grid lines. The diffraction peak intensity I 0002 of the (0002) plane of the Zn phase and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I 0002/I 10-11) is oriented. rate. A region having an orientation ratio of 3.5 or more is defined as a first region, and a region having an orientation ratio of less than 3.5 is defined as a second region.
[Determination method 5]
A virtual grid line is drawn on the surface of the hot-dip plated layer at intervals of 1 mm, and then, for each of a plurality of regions partitioned by the virtual grid line, a circle S centered on the center of gravity G of each region is drawn. The circle S is straight so that the total length of the surface boundary lines of the hot-dip plating layer included in the circle S is 10 mm.Set the diameter R. The average value of the maximum diameter Rmax and the minimum diameter Rmin of the diameters R of the circles S in a plurality of regions is defined as a reference diameter Rave, and the region having the circle S with the diameter R less than the reference diameter Ra is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region.
Effect of the invention
[0014]
According to the hot-dip plated steel sheet of the present invention in which the first region and the second region are specified by the determination methods 1 to 4, the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion By setting the absolute value of the difference to 30% or more, it becomes possible to distinguish between the pattern portion and the non-pattern portion. As a result, it is possible to provide a hot-dip plated steel sheet that is excellent in durability and corrosion resistance when characters, designs, etc. are displayed on the surface of the hot-dip plated layer.
[0015]
Further, according to the hot-dip plated steel sheet of the present invention in which the first region and the second region are specified by the determination method 5, the surface of the hot-dip plated layer is a portion where the density of the boundary line appearing on the surface of the hot-dip plated layer is relatively high and the second region included in the portion where the density of the boundary line appearing on the surface of the hot-dip plating layer is relatively low, and the area ratio of the first region in the pattern portion and the non-pattern portion By setting the absolute value of the difference from the area ratio of the first region to 30% or more, the patterned portion and the non-patterned portion can be distinguished from each other by the difference in boundary line density. As a result, it is possible to provide a hot-dip plated steel sheet that is excellent in durability and corrosion resistance when characters, designs, etc. are displayed on the surface of the hot-dip plated layer.
Brief description of the drawing
[0016]
1] Fig. 1 is a schematic diagram for explaining a method (determining method 5) for determining a first region and a second region in a hot-dip plated steel sheet that is an example of the present embodiment. [Fig.
[Fig. 2] Fig. 2 is a schematic diagram illustrating a method of determining a first region and a second region in a hot-dip plated steel sheet as an example of the present embodiment.
[FIG. 3] FIG. 1-1 is an enlarged photograph of the first region of 1-1 by a scanning electron microscope.
[FIG. 4] FIG. 1-1 is an enlarged photograph taken by a scanning electron microscope of the second region.
5] FIG. 5 is an enlarged plan view showing the surface of the hot-dip plated steel sheet of Example 1. [FIG.
[FIG. 6] FIG. 2-1 is an enlarged photograph of the first region of 2-1 by a scanning electron microscope.
[FIG. 7] FIG. 2-1 is an enlarged photograph of the second region of 2-1 by a scanning electron microscope.
8 is an enlarged plan view showing the surface of the hot-dip plated steel sheet of Example 2. FIG.
[FIG. 9] FIG. It is an enlarged photograph of the pattern portion of 3-1 by a scanning electron microscope.
[FIG. 10] FIG. It is an enlarged photograph of the non-patterned portion of 3-1 taken with a scanning electron microscope.
11] FIG. 11 is an enlarged plan view showing the surface of the hot-dip plated steel sheet of Example 3. [FIG.
[FIG. 12] FIG. FIG. 4 is a schematic diagram showing a boundary line obtained by binarizing the imaging data of the surface of the hot-dip plated layer of 4-1.
[FIG. 13] FIG. 4-1 is an enlarged photograph of the first region of 4-1 by a scanning electron microscope.
[FIG. 14] FIG. 4-1 is an enlarged photograph of the second region of 4-1 by a scanning electron microscope.
15] FIG. 15 is an enlarged plan view showing the surface of the hot-dip plated steel sheet of Example 4. [FIG.
MODE FOR CARRYING OUT THE INVENTION
[0017]
A hot-dip plated steel sheet that is an embodiment of the present invention will be described below.
In this specification, a numerical range represented by "-" means a range including the numerical values ​​before and after "-" as lower and upper limits.
[0018]
(Outline description of the hot-dip plated steel sheet of the present embodiment)
The hot-dip plated steel sheet of the present embodiment includes a steel plate and a hot-dip plated layer formed on the surface of the steel plate, and the hot-dip plated layer has an average composition of Al: 0 to 90% by mass and Mg: 0 to 10% by mass. %, the balance containing Zn and impurities, the hot-dip plated layer includes a patterned portion arranged to have a predetermined shape and a non-patterned portion, and any one of the following determination methods 1 to 5 When the first region and the second region are defined by The hot-dip plated steel sheet, wherein the absolute value of the difference between the area ratio and the area ratio of the first region in the non-patterned portion is 30% or more.
In the hot-dip plated layer of this hot-dip plated steel sheet, when the first region and the second region are determined by any one of the following determination methods 1 to 5, the pattern portion and the non-pattern portion are respectively the first region, and one or two of the second region.
That is, the first and second regions in the pattern portion and the first and second regions in the non-pattern portion are defined by the same determination method. For example, when the first and second regions of the pattern portion are defined by the determination method 1, the first and second regions of the non-pattern portion are defined by the determination method 1.
[0019]
The hot-dip plated steel sheet of the present embodiment includes a steel plate and a hot-dip plated layer formed on the surface of the steel plate, and the hot-dip plated layer has an average composition of Al: 0 to 90% by mass, Mg: 0 to 10% by mass, the balance containing Zn and impurities, and the hot-dip plating layer includes a pattern portion and a non-pattern portion arranged to have a predetermined shape, and the pattern portion and the non-pattern portion are each , including one or two of the first region and the second region determined by any of the following determination methods 1 to 5, the area ratio of the first region in the pattern portion, and the non-pattern portion The hot dip plated steel sheet may have an absolute value of difference from the area ratio of the first region of 30% or more.
In this hot-dip plated layer, the patterned portion and the non-patterned portion each include one or two of the first region and the second region determined by any of the following determination methods 1 to 5. .
That is, in the present invention, there are five types of determination methods 1 to 5 for determining the first region and the second region. The determination method for the two regions may be the same determination method, or the determination method for the first region of the pattern portion and the determination method for the second region of the pattern portion may be different determination methods. Similarly, the determination method for the first region of the non-pattern portion and the determination method for the second region of the non-pattern portion may be the same determination method or different determination methods.
Also, the determination method of the first region of the pattern portion and the determination method of the first region of the non-pattern portion may be the same determination method, or may be different determination methods. Similarly, the determination method for the second region of the pattern portion and the determination method for the second region of the non-pattern portion may be the same determination method, or may be different determination methods.
Furthermore, the first and second regions in the pattern portion and the first and second regions in the non-pattern portion may be defined by the same determination method. For example, when the first and second regions of the pattern portion are defined by the determination method 1, the first and second regions of the non-pattern portion may be defined by the determination method 1.
[0020]
Regarding the surface of the hot-dip plating layer according to this embodiment, it is preferable to determine the first region and the second region by the same determination method. In addition, it is more preferable that the method of determining the first area and the second area be the same for the pattern area and the non-pattern area. That is, it is more preferable that the first and second regions of the pattern portion and the first and second regions of the non-pattern portion are all distinguished by the same determination method. For example, when the first and second regions of the pattern portion are defined by the determination method 1, it is more preferable to similarly define the first and second regions of the non-pattern portion by the determination method 1 as well.
[0021]
[Determination method 1]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. An area A is defined, and the L* value in each measurement area A is measured. 50 points are selected arbitrarily from the obtained L* values, and the average of the 50 points of the obtained L* values ​​is used as the reference L* value. 1 region, and the region where the L* value is less than the reference L* value is defined as the second region.
[0022]
[Determination method 2]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. The L* value is measured in each measurement area A, the area where the L* value is 45 or more is defined as the first area, and the area where the L* value is less than 45 is defined as the second area.
[0023]
[Determination method 3]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual grid lines. The region where the obtained Sa is 1 μm or more is defined as the first region, and the region where the obtained Sa is less than 1 μm is defined as the second region.
[0024]
[Determination method 4]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm or 10 mm, and X-rays are incident on a plurality of regions partitioned by the virtual grid lines. The diffraction peak intensity I 0002 of the (0002) plane of the Zn phase and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I 0002/I 10-11) is oriented. rate. A region having an orientation ratio of 3.5 or more is defined as a first region, and a region having an orientation ratio of less than 3.5 is defined as a second region.
[0025]
[Determination method 5]
A virtual grid line is drawn on the surface of the hot-dip plated layer at intervals of 1 mm, and then, for each of a plurality of regions partitioned by the virtual grid line, a circle S centered on the center of gravity G of each region is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the hot-dip plating layers included in the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin of the diameters R of the circles S in a plurality of regions is defined as a reference diameter Rave, and the region having the circle S with the diameter R less than the reference diameter Ra is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region.
[0026]
(Description of determination methods 1 and 2)
Decision method 1 is as follows. Draw virtual grid lines at intervals of 0.5 mm on the surface of the hot-dip plating layer, and in each of the plurality of regions partitioned by the virtual grid lines, the measurement area A is a circle with a diameter of 0.5 mm centered on the center of gravity of each region. , and the L* value in each measurement area A is measured. Also, 50 points are arbitrarily selected from the obtained L* values, and the average of the 50 points is used as the reference L* value.
In determination method 2, the reference L* value in determination method 1 is set to 45. Otherwise, determination method 2 is the same as determination method 1.
[0027]
In the hot-dip plated steel sheet of the present embodiment, when virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, each of the plurality of regions partitioned by the virtual grid lines is the first It is divided into either an area or a second area.
[0028]
The first area is an area where the L* value is greater than or equal to the reference L* value. On the other hand, the second area is an area where the L* value is less than the reference L* value. Since the first region has a large L* value, the location where the first region is included in the hot-dip plated layer is relatively whiter than the location where the second region is included when observed with the naked eye or under a microscope. Or it looks like a color close to white. In addition, since the second region has a small L* value, the location where the second region is included in the hot dip plated layer and the first region is decreased has a relatively metallic luster compared to the location where the first region is included. or appears dark. Furthermore, the first region and the second region coexist, and the portion where the area ratio of the first region is 30 to 70% looks relatively satin-like in appearance.
[0029]
(Description of determination method 3)
Decision method 3 is as follows. Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual grid lines.
[0030]
In the hot-dip plated steel sheet of this embodiment, virtual grid lines are formed on the surface of the hot-dip plated layer at intervals of 0.5 mm.When drawn, each of the plurality of regions defined by the virtual grid lines is divided into either the first region or the second region according to the arithmetic mean surface roughness Sa.
[0031]
The first area is an area where the arithmetic mean surface roughness Sa is 1 μm or more. On the other hand, the second region is a region with an arithmetic mean surface roughness Sa of less than 1 μm. Since the first region has a large arithmetic mean surface roughness Sa, the location where the first region is included in the hot-dip plated layer is relatively large compared to the location where the second region is included when observed with the naked eye or under a microscope. It looks white or close to white. Since the second region has a small arithmetic mean surface roughness Sa, the part where the second region is included in the hot-dip plated layer and the first region is small is observed with the naked eye or under a microscope. It appears to have a relatively metallic luster compared to the included parts. Furthermore, the first region and the second region coexist, and the portion where the area ratio of the first region is 30 to 70% looks relatively satin-like in appearance.
[0032]
(Description of determination method 4)
Determination method 4 is as follows. Zn phase (0002 ) plane diffraction peak intensity I 0002 and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I 0002/I 10-11) is taken as the orientation ratio. . Note that "-1" in (10-11) means that a bar is added above "1".
[0033]
In the hot-dip plated steel sheet of the present embodiment, when virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm or 10 mm, the plurality of regions partitioned by the virtual grid lines have an orientation ratio (I 0002/I 10 -11), it is divided into either the first region or the second region.
[0034]
The present inventors measured the orientation ratio by performing X-ray diffraction measurement for each region partitioned by virtual lattice lines, and examined the relationship between the appearance of each region and the orientation ratio. It has been found that the appearance of the region becomes relatively white, and the lower the orientation ratio, the more metallic luster the appearance of the region. It has been found that such a relationship between the orientation ratio and the appearance is not confirmed in the Al phase and the MgZn2 phase, but can be confirmed in the case of the Zn phase.
[0035]
The first region is a region with an orientation ratio of 3.5 or higher. On the other hand, the second region is a region with an orientation ratio of less than 3.5. Since the first region has a high orientation ratio, a portion of the hot-dip plated layer that contains a large amount of the first region is relatively white or white compared to a portion that contains a large amount of the second region when observed with the naked eye or under a microscope. It looks almost white. Since the orientation ratio of the second region is low, the portion of the hot-dip plated layer containing a large amount of the second region and a small amount of the first region is relatively small compared to the portion containing a large amount of the first region with the naked eye or under a microscope. appears to have a metallic luster. Furthermore, the first region and the second region coexist, and the portion where the area ratio of the first region is 30 to 70% looks relatively satin-like in appearance.
[0036]
(Description of determination method 5)
Determination method 5 is as follows. Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm, and then, for each of a plurality of regions partitioned by the virtual grid lines, a circle S centered on the center of gravity G of each region is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the hot-dip plating layers included in the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin of the diameters R of the circles S in a plurality of regions is defined as a reference diameter Rave, and the region having the circle S with the diameter R less than the reference diameter Ra is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region.
[0037]
Boundary lines that appear in the hot-dip plating layer include, for example, grain boundaries that appear on the plating surface, and boundaries between high-brightness areas and low-brightness areas on the plating surface.
[0038]
The area included in the high-density portion of the crystal grain boundary appearing on the plated surface, or the area included in the low-density portion of the crystal grain boundary, is arranged so that it is shaped like a straight line or letter on the plated surface. Then, it is recognized that there are straight lines and characters on the plating surface.
[0039]
Similarly, the area included in the part of the plated surface with a high density of light and dark boundaries, or the area included in the part with a low density of light and dark boundaries on the plated surface, should be shaped like a straight line or a letter on the plated surface. , it is recognized that there are straight lines or characters on the plating surface.
[0040]
Therefore, the inventors tried to divide the surface of the hot-dip plated layer into the first region and the second region according to the density of the boundary line appearing on the plated surface.
[0041]
In the hot-dip plated steel sheet of the present embodiment, when virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm, a plurality of regions partitioned by the virtual grid lines are hot-dip plated in the vicinity of each partitioned region. Depending on the density of the surface boundaries of the layer, it is divided into either the first region or the second region.
[0042]
The first region is a region included in a high-density portion of boundary lines appearing on the surface of the hot-dip plating layer. Further, the second region is a region included in a portion where the density of boundary lines appearing on the surface of the hot-dip plating layer is low. In the hot-dip plated layer, the locations where the first regions are gathered and the locations where the second regions are gathered have different boundary line densities, so the first regions and the second regions look relatively different.
[0043]
(In the hot-dip plated steel sheet of the present embodiment, the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion should be 30% or more)
As described above, in determination methods 1 to 4, depending on the area ratio of the first region, the surface of the hot-dip plated layer is relatively white or close to white, metallic luster or low brightness, or satin-like. appear.
In addition, in determination method 5, the first region is a region included in a portion where the density of boundary lines appearing on the surface of the hot-dip plating layer is high, and the second region is the density of boundary lines appearing on the surface of the hot-dip plating layer. Since the region is included in a portion where is low, the density of the boundary line is different between the location where the first region is gathered and the location where the second region is gathered in the hot dip plated layer, and the first region and the second region are relative. look quite different.
[0044]
Here, in order to make characters, figures, lines, dots, patterns, etc. visible on the surface of the hot-dip plated layer, the pattern parts constituting these characters and the like and the other non-pattern parts I wish I could identify it. For this purpose, the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion should be different.
[0045]
Specifically, the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is preferably 30% or more. This makes it possible to distinguish between the pattern portion and the non-pattern portion.
[0046]
In determination methods 1 to 4, for example, when the area ratio of the first region of the pattern portion is 75%, the pattern portion appears relatively white or close to white. In addition, when the area ratio of the first region in the non-pattern portion is 45% or less, it looks relatively satin-like or metallically lustrous. Furthermore, in the case of determination methods 1 and 2, the color may appear to have relatively low lightness. When the difference in the area ratio of the first region between the patterned portion and the non-patterned portion is 30% or more, the patterned portion and the non-patterned portion can be distinguished from each other due to the difference in appearance.
[0047]
Further, when the area ratio of the first region of the pattern portion is about 65% and the area ratio of the first region of the non-pattern portion is about 35%, both the pattern portion and the non-pattern portion are relatively satin-like. Although visible, the patterned portion has a relatively whiter appearance to the non-patterned portion due to the larger area percentage of the first region in the patterned portion. When the difference in the area ratio of the first region between the patterned portion and the non-patterned portion is 30% or more, the patterned portion and the non-patterned portion can be distinguished from each other due to the difference in appearance.
[0048]
Furthermore, when the first area of ​​the pattern portion is 50%, the pattern portion appears relatively satin-like. Further, when the area ratio of the first region in the non-pattern portion is 20% or less, the color appears to have a relatively metallic luster or a low brightness. When the difference in the area ratio of the first region between the patterned portion and the non-patterned portion is 30% or more, the patterned portion and the non-patterned portion can be distinguished from each other due to the difference in appearance.
[0049]
Also, in determination method 5, for example, when the pattern portion includes many first regions, many boundary lines appear in the pattern portion. In this case, the area ratio of the first region in the non-pattern portion is reduced. Since the area ratio of the first region is small in the non-pattern portion, the area ratio of the second region is relatively high. As a result, it becomes possible to distinguish between the patterned portion in which many boundary lines are visible and the non-patterned portion in which few boundary lines are visible with the naked eye, under a magnifying glass, or under a microscope.
[0050]
Also, when the pattern portion includes many second regions, the pattern portion appears to have fewer boundary lines. In this case, the area ratio of the second region in the non-pattern portion is decreased and the area ratio of the first region is increased. Since the non-pattern portion has a large area ratio of the first region, many boundary lines appear in the non-pattern portion. This makes it possible to distinguish between a patterned portion in which few boundary lines appear and a non-patterned portion in which many boundary lines appear with the naked eye, under a magnifying glass, or under a microscope.
[0051]
As described above, in determination methods 1 to 5, when the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more, the pattern portion and the non-pattern portion Since the appearance of the portions becomes relatively different, the pattern portions can be clearly identified. That is, in the visible light image of the surface of the plating layer, since the difference in relative hue, brightness, saturation, etc. between the patterned portion and the non-patterned portion increases, the patterned portion and the non-patterned portion can be distinguished.
[0052]
On the other hand, when the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is less than 30%, there is no relative difference in appearance between the pattern portion and the non-pattern portion. , the pattern portion cannot be clearly identified. That is, in the visible light image of the plating layer surface, since the difference in relative hue, brightness, saturation, etc. between the patterned portion and the non-patterned portion becomes small, the patterned portion and the non-patterned portion cannot be distinguished.
[0053]
As described above, an example of the existence ratio of the first region in the pattern portion and the non-pattern portion was shown. The value may be 30% or more, and there is no need to limit the existence ratio of the first region in each of the pattern portion and the non-pattern portion.
[0054]
A hot-dip plated steel sheet according to an embodiment of the present invention will be described below.
[0055]
(steel plate)
There are no particular restrictions on the material of the steel plate that serves as the base for the hot-dip plating layer. Although the details will be described later, as the material, general steel can be used without any particular limitation, Al-killed steel or some high-alloy steel can also be used, and the shape is also not particularly limited. The hot-dip plating layer according to the present embodiment is formed by applying the hot-dip plating method, which will be described later, to the steel sheet.
[0056]
(Chemical composition of hot-dip plating layer)
Next, the chemical composition of the hot-dip plating layer will be explained.
The hot-dip plated layer has an average composition of 0 to 90% by mass of Al and 0 to 10% by mass of Mg, with the balance being Zn and impurities. More preferably, the average composition contains 4 to 22% by mass of Al, 1 to 10% by mass of Mg, and the balance is Zn and impurities. More preferably, the average composition contains 4 to 22% by mass of Al, 1 to 10% by mass of Mg, and the balance is Zn and impurities. Further, the hot-dip plated layer may contain Si: 0.0001 to 2% by mass in average composition. Furthermore, the hot-dip layer has an average composition of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, C eitherIt may contain 0.0001 to 2% by mass of one or two or more in total.
[0057]
The content of Al is in the range of 0 to 90% by mass, preferably 4 to 22% by mass in terms of average composition. Al is preferably contained in order to ensure corrosion resistance. If the content of Al in the hot-dip plated layer is 4% by mass or more, the effect of improving the corrosion resistance is enhanced. If it is 90% or less, the plating layer can be stably formed. Moreover, if the Al content exceeds 90%, it may take a long time to impart the design, making the production difficult in practice. Furthermore, when the Al content exceeds 90%, the abundance of Zn becomes so small that the first region and the second region cannot be clearly distinguished. Moreover, when the Al content exceeds 22% by mass, the effect of improving the corrosion resistance is saturated. From the viewpoint of corrosion resistance, the content is preferably 5 to 18% by mass. More preferably 6 to 16% by mass
[0058]
The content of Mg is in the range of 0 to 10% by mass, preferably 1 to 10% by mass in terms of the average composition. Mg is preferably contained in order to improve corrosion resistance. If the content of Mg in the hot-dip plated layer is 1% by mass or more, the effect of improving the corrosion resistance is enhanced. If it exceeds 10% by mass, dross generation in the plating bath becomes significant, making it difficult to stably produce a hot-dip plated steel sheet. From the viewpoint of the balance between corrosion resistance and dross generation, the content is preferably 1.5 to 6% by mass. More preferably, it should be in the range of 2 to 5% by mass.
[0059]
Al and Mg may each be 0%. That is, the hot dip plated layer of the hot dip plated steel sheet of the present embodiment is not limited to the Zn—Al—Mg hot dip plated layer, and may be a Zn—Al hot dip plated layer, or a hot dip galvanized layer. It may be an alloyed hot-dip galvanized layer.
[0060]
In addition, the hot dip plated layer may contain Si in the range of 0.0001 to 2% by mass.
Since Si may improve the adhesion of the hot-dip plating layer, it may be contained. By containing 0.0001% by mass or more of Si, the effect of improving adhesion is exhibited, so it is preferable to contain 0.0001% by mass or more of Si. On the other hand, even if the content exceeds 2% by mass, the effect of improving the plating adhesion is saturated, so the content of Si is made 2% by mass or less. From the viewpoint of plating adhesion, it may be in the range of 0.001 to 1% by mass, or in the range of 0.01 to 0.8% by mass.
[0061]
In the hot dip plated layer, the average composition is Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, C may contain 0.001 to 2% by mass in total of one or more of Corrosion resistance can be further improved by containing these elements. REM is one or more of the rare earth elements with atomic numbers 57-71 in the periodic table. Also, the total content of these elements may be 0.0001 to 2% by mass.
[0062]
The rest of the chemical composition of the hot-dip plating layer is zinc and impurities. The hot-dip plated layer always contains Zn. Impurities include those that are unavoidably contained in base metals such as zinc, and those that are contained by dissolving steel in the plating bath.
[0063]
The average composition of the hot dip plated layer can be measured by the following method. First, after removing the surface coating film with a coating remover that does not corrode the plating (for example, Neoriver SP-751 manufactured by Sansai Kako Co., Ltd.), the hot-dipped plating layer with hydrochloric acid containing an inhibitor (for example, Hibilon manufactured by Sugimura Chemical Industry Co., Ltd.) can be determined by dissolving and subjecting the resulting solution to inductively coupled plasma (ICP) emission spectrometry. Moreover, when the surface layer coating film is not provided, the operation for removing the surface layer coating film can be omitted.
[0064]
(Metal structure of hot-dip plating layer)
Next, the structure of the hot-dip plating layer will be explained. The structure described below is the structure when the hot-dip plated layer has an average composition of 4 to 22% by mass of Al, 1 to 10% by mass of Mg, and 0 to 2% by mass of Si.
[0065]
The hot dip plated layer containing Al, Mg and Zn contains [Al phase] and [Al/Zn/MgZn2 ternary eutectic structure]. It has a form in which the [Al phase] is included in the [Al/Zn/MgZn2 ternary eutectic structure] matrix. Further, the [Al/Zn/MgZn2 ternary eutectic structure] matrix may contain [MgZn2 phase] or [Zn phase]. Further, when Si is added, [Mg 2 Si phase] may be included in the base of [Al/Zn/MgZn 2 ternary eutectic structure].
[0066]
Here, the [Al/Zn/MgZn2 ternary eutectic structure] is a ternary eutectic structure of the Al phase, the Zn phase, and the intermetallic compound MgZn2 phase, [Al/Zn/MgZn2 The Al phase forming the ternary eutectic structure] is, for example, the "Al" phase at high temperatures in the Al-Zn-Mg ternary equilibrium diagram (Al solid solution that dissolves Zn, and a small amount of including Mg). At room temperature, the Al″ phase at a high temperature usually appears as a fine Al phase and a fine Zn phase separated from each other. It is a Zn solid solution in which Al is solid-dissolved, and in some cases, a small amount of Mg is also solid-dissolved in. The MgZn 2 phase in [a ternary eutectic structure of Al/Zn/MgZn 2] is a binary system of Zn—Mg. It is an intermetallic compound phase that exists in the vicinity of Zn in the equilibrium diagram: about 84% by mass.As far as the phase diagram is concerned, each phase does not dissolve other additive elements, Although it is considered to be a very small amount, the amount cannot be clearly distinguished by ordinary analysis. ].
[0067]
Further, [Al phase] is a phase that looks like an island with a clear boundary in the [Al/Zn/MgZn2 ternary eutectic structure] matrix. It corresponds to the "Al" phase" (Al solid solution that dissolves Zn and contains a small amount of Mg) at high temperatures in the system equilibrium diagram.
The Al″ phase at high temperature differs in the amount of solid-soluted Zn and Mg depending on the concentration of Al and Mg in the plating bath. It separates into phases, but the island-like shape seen at room temperature can be considered to be the remains of the Al″ phase at high temperature. It is thought that it is not dissolved, or even if it is dissolved, it is a very small amount, but it cannot be clearly distinguished by ordinary analysis. In this specification, the retained phase is called [Al phase], and this [Al phase] is clearly different from the Al phase forming the [Al/Zn/MgZn2 ternary eutectic structure] by microscopic observation. distinguishable.
[0068]
The [Zn phase] is a phase that looks like an island with a clear boundary in the [Al/Zn/MgZn2 ternary eutectic structure] matrix. is sometimes dissolved. As far as the phase diagram is concerned, it is considered that this phase does not dissolve other additive elements or, if dissolved, the amount is extremely small. This [Zn phase] can be clearly distinguished from the Zn phase forming the [ternary eutectic structure of Al/Zn/MgZn2] by microscopic observation. The plating layer of the present invention may contain [Zn phase] depending on the manufacturing conditions. there is no problem either.
[0069]
[MgZn 2 phase] is a phase that looks like islands with clear boundaries in the [Al/Zn/MgZn 2 ternary eutectic structure] matrix. sometimes As far as the phase diagram is concerned, it is considered that this phase does not dissolve other additive elements or, if dissolved, the amount is extremely small. This [MgZn 2 phase] can be clearly distinguished from the MgZn 2 phase forming the [Al/Zn/MgZn 2 ternary eutectic structure] by microscopic observation. The plating layer of the present invention may not contain the [MgZn 2 phase] depending on the production conditions, but it is contained in the plating layer under most production conditions.
[0070]
Also, the [Mg 2 Si phase] is a phase that looks like islands with clear boundaries in the solidified structure of the plating layer when Si is added. As far as the phase diagram is concerned, it is considered that Zn, Al, and other additive elements are not solid-dissolved, or even if they are solid-dissolved, the amount is extremely small. This [Mg 2 Si phase] can be clearly distinguished in the plating by microscopic observation.
[0071]
(Regarding the pattern part and non-pattern part)
Next, the patterned portion and the non-patterned portion on the surface of the hot-dip plating layer will be described.
[0072]
The surface of the hot-dip plating layer of the present embodiment includes a patterned portion arranged to have a predetermined shape and a non-patterned portion. It is preferable that the pattern portion is arranged so as to form any one of linear portions, curved portions, dot portions, figures, numerals, symbols, patterns, or characters, or a combination of two or more of these. . Also, the non-pattern portion is a region other than the pattern portion. Moreover, even if the shape of the pattern portion is partially missing, such as missing dots, it is permissible as long as it can be recognized as a whole. Also, the non-pattern portion may have a shape that borders the boundary of the pattern portion. There is no particular limitation on the area ratio of the patterned portion and the non-patterned portion in the hot-dip plating layer.
[0073]
If any one of straight lines, curved lines, dots, figures, numbers, symbols, patterns or letters, or a combination of two or more of these is arranged on the surface of the hot-dip plating layer, these can be used as the pattern area, and the other area can be used as the non-pattern area. The boundary between the patterned portion and the non-patterned portion can be recognized with the naked eye. The boundary between the patterned portion and the non-patterned portion may be grasped from an enlarged image using an optical microscope or a magnifying glass.
[0074]
The pattern portion is preferably formed to a size that allows the existence of the pattern portion to be determined with the naked eye, under a magnifying glass, or under a microscope. Moreover, the non-pattern portion is a region that occupies most of the hot-dip plated layer (the surface of the hot-dip plated layer), and the pattern portion may be arranged in the non-pattern portion.
The pattern portion is arranged in a predetermined shape within the non-pattern portion. Specifically, in the non-pattern portion, the pattern portion includes any one of linear portions, curved portions, graphics, dot portions, graphics, numerals, symbols, patterns, or characters, or a combination of two or more of these. It is arranged so that it becomes a shape. By adjusting the shape of the pattern portion, any one or more of the straight line portion, curved portion, figure, dot portion, figure, number, symbol, pattern or character may be formed on the surface of the hot-dip plating layer. A shape that combines the For example, on the surface of the hot-dip plated layer, a string of characters, a string of numbers, a symbol, a mark, a diagram, a design image, or a combination of these, etc., formed of a pattern portion appears. This shape is a shape intentionally or artificially formed by a manufacturing method to be described later, and is not naturally formed.
[0075]
Thus, the patterned portion and the non-patterned portion are regions formed on the surface of the hot-dip plating layer. Also, the pattern portion and the non-pattern portion each include one or two of the first region and the second region. The patterned portion and the non-patterned portion may each consist of one or two of the first region and the second region.
[0076]
(Regarding the first area and the second area)
Next, the first area and the second area in determination methods 1 to 5 will be explained.
[0077]
(First area and second area in determination methods 1 and 2)
The first area in determination method 1 is an area including measurement area A in which the L* value obtained by determination method 1 below is equal to or greater than the reference L* value. Also, the second area is an area including the measurement area A in which the L* value obtained by the determination method 1 is less than the reference L* value.
[0078]
A portion of the hot-dip plated layer with a large number of first regions appears relatively white or close to white. On the other hand, theAreas with more two regions appear relatively metallic or dark. Also, the first regions and the second regions gather in a dispersed manner, and the area where the area ratio of the first regions is 30% to 70% looks relatively satin-like in appearance.
[0079]
Note that the first area and the second area may be specified by determination method 2, which will be described later.
[0080]
Next, determination methods 1 and 2 will be explained.
[0081]
In determination method 1, virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and in each of the plurality of regions partitioned by the virtual grid lines, a circle with a diameter of 0.5 mm centered on the center of gravity of each region The inside is defined as a measurement area A, and the L* value in each measurement area A is measured.
[0082]
In determination method 1, virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and a plurality of areas partitioned by these virtual grid lines are set. The shape of each region is a square with a side of 0.5 mm. The area set here becomes either the first area or the second area. A circle having a diameter of 0.5 mm centered on the center of gravity of each area partitioned by virtual grid lines is defined as a measurement area A, and the L* value in each measurement area A is measured.
[0083]
Next, find the reference L* value. The reference L* value is the average value of the L* values ​​of 50 regions arbitrarily selected from a plurality of regions partitioned by virtual grid lines. Arbitrary 50 measurement points for measuring the reference L* value are selected as follows, for example. First, one region is selected from a plurality of regions partitioned by the virtual grid lines. Next, starting from this one area, a total of 50 points of 10 vertical areas×5 horizontal areas (50 mm×25 mm) are selected with an interval of 10 each. A total of 50 points selected in this manner are used as 50 arbitrary measurement points for measuring the reference L* value.
[0084]
Then, in the areas partitioned by the virtual grid lines, the area including the measurement area A in which the L* value is equal to or greater than the reference L* value is defined as the first area, and the measurement area A in which the L* value is less than the reference L* value is defined as the first area. Let the region containing the data be the second region.
[0085]
Also, in determination method 2, the first region and the second region are specified by using L*=45 instead of the reference L* value. That is, virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and a plurality of regions partitioned by the virtual grid lines are set. The shape of each region is a square with a side of 0.5 mm. The area set here becomes the first area or the second area. A centroid point is selected that is demarcated by virtual grid lines. Then, a circle with a diameter of 0.5 mm centered on the center of gravity is defined as a measurement area A, and the L* value in each measurement area A is measured.
[0086]
Then, among the above regions, the region including the measurement region A with the L* value of 45 or more is defined as the first region, and the region including the measurement region A with the L* value of less than 45 is defined as the second region.
[0087]
In the determination methods 1 and 2 above, the L* value is measured according to JIS K 5600-4-5. In this embodiment, of the parameters representing the color space represented by the L*a*b* color system, the L* value representing lightness is used. The L* value is measured by irradiating irradiation light from a halogen lamp as a light source at an angle of 45° with respect to the vertical direction (90° direction) of the surface of the hot-dip plating layer, and measuring the vertical direction of the surface of the hot-dip plating layer. It is measured by receiving reflected light reflected in (90° direction) by a light receiver. A micro-area spectral color difference meter (VSS 7700, manufactured by Nippon Denshoku Industries Co., Ltd.) can be used as an apparatus for measuring the L* value. The measurement wavelength range is 380 nm to 780 nm, and the intensity within this wavelength range is measured at intervals of 5 nm and converted into an L* value.
[0088]
(First region and second region in determination method 3)
Since the first region in determination method 3 is a region with an arithmetic mean surface roughness Sa of 1 μm or more, a portion of the hot-dip plated layer with a large amount of the first region appears relatively white or close to white. On the other hand, portions of the hot-dip plated layer where there are many second regions appear to have a relatively metallic luster. Also, the first regions and the second regions gather in a dispersed manner, and the area where the area ratio of the first regions is 30% to 70% looks relatively satin-like in appearance.
[0089]
Since the first region has an arithmetic mean surface roughness Sa of 1 μm or more, a portion of the hot-dip plated layer with a large amount of the first region appears relatively white or close to white. On the other hand, portions of the hot-dip plated layer where there are many second regions appear to have a relatively metallic luster. Also, the first regions and the second regions gather in a dispersed manner, and the area where the area ratio of the first regions is 30% to 70% looks relatively satin-like in appearance.
[0090]
Next, a method for measuring the arithmetic mean surface roughness Sa will be described.
First, virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa of each region is measured in a plurality of regions partitioned by the virtual grid lines.
A region with an arithmetic mean surface roughness Sa of 1 μm or more is the first region, and a region with an arithmetic mean surface roughness Sa of less than 1 μm is the second region.
[0091]
In determination method 3, the arithmetic mean surface roughness Sa is measured using a 3D laser microscope (manufactured by Keyence Corporation). In this embodiment, a standard lens with a magnification of 20 is used to measure the height Z in each of a plurality of regions partitioned by virtual grid lines at a measurement interval of 50 μm. When measured on a grid, 100 measurement points are obtained in the area. When the obtained height Z100 point is defined as height Z1 to height Z100, Sa is calculated using the following formula. Zave is the average of 100 points of height Z.
Sa = 1/100 × Σ [x = 1 → 100] (|Height Zx-Zave|)
[0092]
(First region and second region in determination method 4)
The first region in determination method 4 is a region with an orientation ratio of 3.5 or more. A portion of the hot-dip plated layer having a large number of first regions appears relatively white or close to white. On the other hand, the second region is a region with an orientation ratio of less than 3.5. A portion of the hot-dip plated layer having a large number of second regions appears to have a relatively metallic luster to the naked eye. In addition, the first regions and the second regions gather in a dispersed manner, and the area where the area ratio of the first regions is 30 to 70% looks relatively satin-like in appearance.
[0093]
Next, the method for measuring the orientation rate will be explained.
First, virtual grid lines are drawn at intervals of 1 mm or 10 mm on the surface of the hot-dip plating layer. Next, the diffraction peak intensity I 0002 of the (0002) plane of the Zn phase was obtained for each region by the X-ray diffraction method in which the X-rays are incident on the centers of gravity points in a plurality of regions partitioned by the virtual lattice lines. and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase. The ratio of these intensities (I 0002/I 10-11) is defined as the orientation ratio.
[0094]
In addition, the strength of the Zn phase measured by the X-ray diffraction method is the Zn phase constituting the [Al/Zn/MgZn 2 ternary eutectic structure], the Zn phase constituting the [Zn phase], and the [Al phase ] is the sum of the intensities of the fine Zn phases constituting the . Of these, the Zn phase constituting the [Al/Zn/MgZn 2 ternary eutectic structure] and the Zn phase constituting the [Zn phase] predominantly contribute to the orientation ratio.
[0095]
　X-ray diffraction measurement uses a Co tube as an X-ray light source. The diffraction peak intensity I 0002 of the (0002) plane of the Zn phase is the intensity of the (0002) plane diffraction peak of the Zn phase appearing in the range of 42.41°±0.5° in the 2θ range. The diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase is the intensity of the diffraction peak of the (10-11) plane of the Zn phase that appears in the range of 50.66° ± 0.5° in the 2θ range. do. Preferably, the step is 0.02°, the scanning speed is 5°/min, and a high-speed semiconductor two-dimensional detector is preferably used.
[0096]
When the interval between the virtual grid lines is 1 mm, it is preferable to condense the X-rays emitted from the X-ray light source with a polycapillary. The irradiation range of the X-rays after condensing is preferably within an elliptical range having a major axis of 1 mm and a minor axis of 0.75 mm. By irradiating each region partitioned by virtual lattice lines at intervals of 1 mm with the X-rays with the irradiation range narrowed in this way, the X-ray diffraction measurement can be performed for each region. For the X-ray diffraction measurement in this case, it is preferable to use an X-ray diffraction apparatus for minute area measurement.
[0097]
When the interval between the virtual grid lines is 10 mm, it is preferable to condense the X-rays emitted from the X-ray light source by ordinary means. The irradiation range of the X-rays after condensing is preferably within a rectangular range of 10 mm long and 10 mm wide. X-ray diffraction measurement can be performed for each region by irradiating each region partitioned by virtual lattice lines at intervals of 10 mm with the X-ray whose irradiation range is narrowed in this way. For the X-ray diffraction measurement in this case, it is preferable to use a normal X-ray diffraction device.
[0098]
The spacing of the virtual grid lines may be appropriately set according to the size of the pattern portion and the size of the hot-dip plating layer. In the case where the straight line portion or the pattern portion representing characters or the like is relatively small, if the interval between the virtual grid lines is set to 10 mm, the area defined by the virtual grid line is located across both the pattern portion and the non-pattern portion. can happen. Therefore, when the minimum width of the pattern portion is less than 10 mm, it is preferable to set the interval of the virtual grid lines to 1 mm or less. On the other hand, when the minimum width of the pattern portion exceeds 10 mm, the interval between virtual grid lines may be 10 mm or 1 mm.
[0099]
(First region and second region in determination method 5)
The first area in determination method 5 is an area included in a portion where the density of boundary lines appearing on the surface of the hot-dip plating layer is high. Further, the second region is a region included in a portion where the density of boundary lines appearing on the surface of the hot-dip plating layer is low. The location where the first regions are concentrated and the location where the second regions are concentrated in the hot-dip plated layer can be identified because the density of the boundary line is different.
[0100]
Next, a method for determining the first area and the second area will be described with reference to FIG.
As shown in Fig. 1, virtual grid lines K are drawn on the surface of the hot-dip plated layer at intervals of 1 mm. In FIG. 1, the virtual grid lines are indicated by dashed-dotted lines. Note that FIG. 1 does not show a boundary line where the hot-dip plating layer appears. Next, a plurality of regions M partitioned by virtual grid lines K are set. The shape of each region M is a square with a side of 1 mm. The area set here becomes either the first area or the second area. Next, for each of a plurality of regions M partitioned by the virtual grid lines K, the center of gravity G of each region is set. Next, a circle S centered on the center of gravity G is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the hot-dip plating layers included inside the circle S is 10 mm.
[0101]
A circle S corresponding to an arbitrary region M is shown in FIGS. 2(a) and 2(b). 2(a) and 2(b) show boundary lines appearing on the surface of the hot-dip plating layer. The boundary lines shown in FIGS. 2(a) and 2(b) both have a total length of 10 mm. In this embodiment, the diameter of the circle S is adjusted so that the total length of the boundary lines L included in the circle S is 10 mm. Therefore, as shown in FIG. 2A, when there are many boundary lines L in and around the area M, the diameter R of the circle S is relatively small. On the other hand, as shown in FIG. 2B, when there are relatively few boundary lines L in and around the region M, the diameter R of the circle S is relatively large. A circle S is drawn for all regions and the diameter R of each circle S is determined.
[0102]
Then, the average value of the maximum diameter Rmax and the minimum diameter Rmin of the circles S in the plurality of regions M is defined as a reference diameter Rave, and the region having the circle S whose diameter R is less than the reference diameter Rave is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region. The first area is an area included in a portion where many boundary lines L exist, as shown in FIG. 2(a). It becomes a region included in a portion that exists in a small amount.
[0103]
The boundaries that appear in the hot-dip plating layer can be exemplified by grain boundaries that appear on the plating surface, and boundaries between high-brightness and low-brightness portions of the plating surface. In addition, the high-brightness part and the low-brightness partThe boundary with minutes may be a boundary line obtained by binarizing the imaging of the plating surface.
[0104]
(Regarding the first and second regions in the pattern portion and non-pattern portion in determination methods 1 to 5)
The pattern portion includes a plurality of regions partitioned by virtual grid lines, and each region is classified as either a first region or a second region. The non-pattern portion also includes a plurality of regions partitioned by virtual grid lines, and each region is classified as either a first region or a second region. That is, the pattern portion may include either the first region or the second region, or may include both the first region and the second region. Similarly, the non-pattern portion may include either the first region or the second region, or may include both the first region and the second region.
[0105]
Here, in the pattern portion, the area ratio of each of the first region and the second region can be obtained.
In determination methods 1 to 4, when the area fraction of the first region exceeds 70%, the pattern portion appears relatively white or close to white. When the area fraction of the first region is 30% or more and 70% or less, the pattern portion looks relatively satin-like. In addition, when the area fraction of the first region is less than 30%, the pattern portion has a relatively metallic luster or looks dark.
Also, in determination method 5, when the area fraction of the first region increases, the pattern portion includes a relatively large number of boundary lines. On the other hand, when the area fraction of the second region in the pattern portion is high, the pattern portion includes relatively few boundary lines.
Thus, the appearance of the pattern portion depends on the area fraction of the first region.
[0106]
On the other hand, even in the non-pattern portion, the area ratio of each of the first region and the second region can be obtained. As with the patterned portion, the appearance of the non-patterned portion depends on the area fraction of the first region.
[0107]
When the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more, the pattern portion and the non-pattern portion can be distinguished. Become. When the difference in area ratio is less than 30%, the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is small, and the appearance of the pattern portion and the non-pattern portion are similar. It becomes an appearance, and it becomes difficult to identify the pattern portion. The larger the difference in the area ratio, the better, more preferably 40% or more, and even more preferably 60% or more.
[0108]
The patterned portion and the non-patterned portion may be identifiable with the naked eye, or may be identifiable under a magnifying glass or a microscope. Being identifiable under a magnifying glass or a microscope means, for example, that the shape formed by the pattern portion is identifiable in a field of view of 50 times or less. With a field of view of 50 times or less, the patterned portion and the non-patterned portion can be distinguished from each other by the relative difference in appearance. The patterned portion and the non-patterned portion are preferably distinguishable by a factor of 20 or less, more preferably by a factor of 10 or less, and more preferably by a factor of 5 or less.
[0109]
(Chemical conversion treatment layer, coating layer)
The hot-dip plated steel sheet according to this embodiment may have a chemical conversion film layer or a coating film layer on the surface of the hot-dip plated layer. Here, the types of the chemical conversion treatment film layer and the coating film layer are not particularly limited, and known chemical conversion treatment film layers and coating film layers can be used.
[0110]
(Manufacturing method of hot-dip plated steel sheet)
Next, a method for manufacturing the hot-dip plated steel sheet of this embodiment will be described.
[0111]
The hot-dip plated steel sheet of the present embodiment is hot-dip plated on a steel plate manufactured through steelmaking, casting, and hot rolling. When manufacturing the steel sheet, pickling, hot-rolled sheet annealing, cold rolling, and cold-rolled sheet annealing may be further performed. Hot-dip plating may be a continuous hot-dip plating method in which a steel sheet is continuously passed through a hot-dip plating bath, or a hot-dip plating method in which a steel material processed into a predetermined shape or the steel plate itself is immersed in a hot-dip plating bath and then pulled out. It's okay.
[0112]
The hot-dip plating bath preferably contains 0 to 90% by mass of Al, 0 to 10% by mass of Mg, and the balance of Zn and impurities. The hot-dip plating bath may contain 4 to 22% by mass of Al, 1 to 10% by mass of Mg, and the balance may be Zn and impurities. Furthermore, the hot dip plating bath may contain Si: 0.0001 to 2% by mass. Furthermore, the hot-dip plating bath is Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, or C. One or two or more may be contained in a total amount of 0.0001 to 2% by mass. The average composition of the hot-dip plating layer of this embodiment is substantially the same as the composition of the hot-dip plating bath.
[0113]
The temperature of the hot-dip plating bath varies depending on the composition, but is preferably in the range of 400-500°C, for example. This is because a desired hot-dip plating layer can be formed if the temperature of the hot-dip plating bath is within this range.

The scope of the claims
[Claim 1]
A steel plate and a hot-dip coating layer formed on the surface of the steel plate,
The hot-dip plated layer contains, in average composition, Al: 0 to 90% by mass, Mg: 0 to 10% by mass, the balance being Zn and impurities,
The hot-dip plating layer includes a pattern portion arranged to have a predetermined shape and a non-pattern portion,
When the first and second areas are determined by any one of the following determination methods 1 to 5,
the pattern portion and the non-pattern portion are each composed of one or two of the first region and the second region,
A hot-dip plated steel sheet, wherein the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more.
[Determination method 1]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. A region is designated as A, and the L* value in each measurement region A is measured. Select arbitrarily 50 points from the obtained L* values, and use the average of the obtained L* values ​​for 50 points as the reference L* value. 1 region, and the region where the value is less than the reference L* value is defined as the second region.
[Determination method 2]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. The L* value is measured in each measurement area A, and the area where the L* value is 45 or more is defined as the first area, and the area where the L* value is less than 45 is defined as the second area.
[Determination method 3]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual grid lines. The region where the obtained Sa is 1 μm or more is defined as the first region, and the region where the obtained Sa is less than 1 μm is defined as the second region.
[Determination method 4]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm or 10 mm, and X-rays are incident on a plurality of regions partitioned by the virtual grid lines. The diffraction peak intensity I 0002 of the (0002) plane of the Zn phase and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I 0002/I 10-11) is oriented. rate. A region having an orientation ratio of 3.5 or more is defined as a first region, and a region having an orientation ratio of less than 3.5 is defined as a second region.
[Determination method 5]
A virtual grid line is drawn on the surface of the hot-dip plated layer at intervals of 1 mm, and then, for each of a plurality of regions partitioned by the virtual grid line, a circle S centered on the center of gravity G of each region is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the hot-dip plating layers included in the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin of the diameters R of the circles S in a plurality of regions is defined as a reference diameter Rave, and the region having the circle S with the diameter R less than the reference diameter Ra is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region.
[Claim 2]
The hot-dip plated steel sheet according to claim 1, wherein the hot-dip plated layer contains, in average composition, Al: 4 to 22% by mass, Mg: 1 to 10% by mass, and the balance containing Zn and impurities. .
[Claim 3]
The hot dip plated steel sheet according to claim 1 or claim 2, wherein the hot dip plated layer further contains Si: 0.0001 to 2 mass% in average composition.
[Claim 4]
The hot-dip plated layer further has an average composition of Ni, Ti, Zr, Sr, Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, Sc, Y, REM, Hf, 4. The hot dip plated steel sheet according to any one of claims 1 to 3, characterized by containing 0.0001 to 2% by mass of any one or more of C in total.
[Claim 5]
The pattern portion is arranged so as to form any one of linear portions, curved portions, dot portions, figures, numerals, symbols, patterns, or characters, or a combination of two or more of these. The hot-dip plated steel sheet according to any one of claims 1 to 4.
[Claim 6]
The hot-dip plated steel sheet according to any one of claims 1 to 5, wherein the pattern portion is intentionally formed.
[Claim 7]
The hot-dip plated steel sheet according to any one of claims 1 to 6, wherein the total amount of the hot-dip plated layer on both sides of the steel sheet is 30 to 600 g/m 2 .
[Claim 8]
A steel plate and a hot-dip coating layer formed on the surface of the steel plate,
The hot-dip plated layer contains, in average composition, Al: 0 to 90% by mass, Mg: 0 to 10% by mass, the balance being Zn and impurities,
The hot-dip plating layer includes a pattern portion arranged to have a predetermined shape and a non-pattern portion,
The pattern portion and the non-pattern portion each include one or two of a first region and a second region determined by any of the following determination methods 1 to 5,
A hot-dip plated steel sheet, wherein the absolute value of the difference between the area ratio of the first region in the pattern portion and the area ratio of the first region in the non-pattern portion is 30% or more.
[Determination method 1]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. A region is designated as A, and the L* value in each measurement region A is measured. Select arbitrarily 50 points from the obtained L* values, and use the average of the obtained L* values ​​for 50 points as the reference L* value. 1 region, and the region where the value is less than the reference L* value is defined as the second region.
[Determination method 2]
Draw virtual grid lines on the surface of the hot-dip plated layer at intervals of 0.5 mm, and measure the inside of a circle with a diameter of 0.5 mm centered on the center of gravity of each region in a plurality of regions partitioned by the virtual grid lines. The L* value is measured in each measurement area A, and the area where the L* value is 45 or more is defined as the first area, and the area where the L* value is less than 45 is defined as the second area.
[Determination method 3]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 0.5 mm, and the arithmetic mean surface roughness Sa is measured in each of a plurality of regions partitioned by the virtual grid lines. The region where the obtained Sa is 1 μm or more is defined as the first region, and the region where the obtained Sa is less than 1 μm is defined as the second region.
[Determination method 4]
Virtual grid lines are drawn on the surface of the hot-dip plated layer at intervals of 1 mm or 10 mm, and X-rays are incident on a plurality of regions partitioned by the virtual grid lines. The diffraction peak intensity I 0002 of the (0002) plane of the Zn phase and the diffraction peak intensity I 10-11 of the (10-11) plane of the Zn phase are measured, and the ratio of these intensities (I 0002/I 10-11) is oriented. rate. A region having an orientation ratio of 3.5 or more is defined as a first region, and a region having an orientation ratio of less than 3.5 is defined as a second region.
[Determination method 5]
A virtual grid line is drawn on the surface of the hot-dip plated layer at intervals of 1 mm, and then, for each of a plurality of regions partitioned by the virtual grid line, a circle S centered on the center of gravity G of each region is drawn. The diameter R of the circle S is set so that the total length of the surface boundary lines of the hot-dip plating layers included in the circle S is 10 mm. The average value of the maximum diameter Rmax and the minimum diameter Rmin of the diameters R of the circles S in a plurality of regions is defined as a reference diameter Rave, and the region having the circle S with the diameter R less than the reference diameter Ra is defined as the first region. A region having a circle S whose R is equal to or greater than the reference diameter Rave is defined as a second region.