KR100881777B1 - HIGHLY CORROSION RESISTANT Zn ALLOY PLATED STEEL MATERIAL HAVING HAIRLINE APPEARANCE - Google Patents

Abstract

The present invention provides a highly corrosion-resistant zinc-based alloy plated steel having a hairline appearance that can be applied to the same use as that of stainless steel, the plating adhesion amount is 10 to 600 g / m ² , Al: 1 to 60 mass %, Mg: 0.1 to 10% by mass, the remainder having a hairline formed on the surface layer of the plating layer made of Zn and unavoidable impurities, the hairline has a surface roughness (Ra) of 0.2 to 2.5 ㎛ in the direction perpendicular to the hairline, The number of peaks (PPI) is 50 to 400, the surface roughness (Ra) in the hairline direction is 0.1 to 1.2 µm, the number of peaks (PPI) is 1 to 100, and the surface roughness (Ra) in the direction perpendicular to the hairline is hair. A high corrosion resistance Zn-based alloy plated steel having a hairline appearance, characterized in that 1.2 times or more of the surface roughness Ra in the line direction, and PPI in the direction perpendicular to the hairline is 2.0 times or more than the PPI in the hairline direction.

Hairline appearance, Zn alloy plating steel

Description

High Corrosion Resistant Zn-Based Alloy Plated Steel with Hairline Appearance {HIGHLY CORROSION RESISTANT Zn ALLOY PLATED STEEL MATERIAL HAVING HAIRLINE APPEARANCE}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly corrosion-resistant Zn-based alloy plated steel having a hairline appearance used for interior materials, exterior materials, such as buildings and vehicles, and surface materials of electrical equipment.

Stainless steels are well known as steel having a conventional hairline appearance. That is, the hairline finish (HL finish) is defined in JIS G 4305 and 4307 as one of the surface finishes of stainless steels, and the hairline finish is "polishing finished with abrasive grains of suitable particle size so that a continuous polishing mark remains." As defined herein, it means a continuous surface finish in which the polishing surface is as long as the hair.

1 is a diagram showing an outline of hairline finishing. In the conventional hairline finishing method, as shown in FIG. 1, by rotating the contact wheel, the endless paper polishing belt 3 wound around the contact wheel 1 and the idle roll 2 is rotated at high speed to uncoiler ( It is well known that it is the processing method of grinding the surface of the stainless steel 6 which moves from 4) to the coiler 5 with a polishing belt (For example, Unexamined-Japanese-Patent No. 1-306162 and Unexamined-Japanese-Patent No. 7-96183). Reference). Stainless steels with hairline finishes are widely used for interior materials, exterior materials, and surface layers of electrical equipment, where design is important because they have corrosion resistance and unique surface shapes.

However, since stainless steel is expensive, a new inexpensive material replacing stainless steel has a high corrosion resistance equivalent to that of stainless steel, and a steel having a hairline appearance suitable for use in building materials or electrical equipment is required.

Therefore, the present inventors paid attention to zinc-plated steel, which is excellent in corrosion resistance and low in corrosion resistance, such as stainless steel, and studied that the hairline finish was applied thereto.

As a conventional technique of finishing the hairline on the plating layer, when the plating coating layer is formed on the surface of the thin and light magnesium-based member, and the hairline shape is formed on the surface of the plating coating layer by the hairline finishing, the underlying metal of the plating coating layer is exposed. The technique which solved the problem that the corrosion resistance falls and a stable high quality member cannot be obtained is proposed.

That is, the plating coating layer (1) selected from Cu, Cu alloy, Au, Au alloy, Al, Al alloy formed on the surface of the Mg-based component by dry plating method, and further formed by the wet plating method on the plating coating layer (1) A technique for hairline finishing a surface of an Mg-based part having a plating coating layer 2 selected from Cu, Ni, Au, Cr, Zn, Pa, Pt, Rh, Fe, Co, Sn, Cd, Ru, and alloys thereof. (See, for example, Japanese Patent Application Laid-Open No. 2000-219977). However, this technique is required to form a thick plated coating layer in duplicate and requires a combination of dry plating method and wet plating method, and therefore it is difficult to adapt this technology to galvanized steel as it is.

In addition, various inventions have been made on the highly corrosion-resistant Zn-based alloy coated steel sheet. For example, Zn-Al-Mg-based alloy coated steel sheet has a mass% of Al: 3 to 17%, Mg: 1 to 5%, and balance Zn. A plated steel sheet using a plating bath consisting of a coated bath, a plated steel sheet using a plating bath in which Ti and B are added thereto (see, for example, Japanese Unexamined Patent Publication No. 10-306357), or a Zn-Al-Mg-Si-based alloy The plated steel sheet has a plating layer containing Al: 5 to 8%, Mg: 1 to 10%, Si: 0.01 to 2%, Fe: 1% or less, or additionally Sn: 0.1 to 2% by mass%. Plated steel sheets are known (see, for example, Japanese Patent Application Laid-Open No. 2001-355053).

It is an object of the present invention to provide a highly corrosion-resistant zinc-based alloy plated steel having a hairline appearance, which can be applied to the same use as that of a stainless steel having a hairline appearance.

The present inventors earnestly studied about giving a hairline finish to a galvanized steel, which is a material which is cheaper than stainless steel and has the same corrosion resistance as a material to replace a stainless steel having a hairline appearance. As a result, when a hairline finish is applied to a pure galvanized steel, the hairline formed is easy to break down because zinc is soft, and the hairline is easily attached to the polishing belt for finishing the hairline during processing. It was difficult to finish the hairline. In addition, in the galvanized steel material subjected to the hairline finish, white blue is generated on the zinc surface in the air, and when white blue is generated, the appearance of the hairline is lost and the effect of forming the hairline is lost.

Therefore, in the present invention, paying attention to the high corrosion-resistant Zn-based alloy plating containing a hard phase in the plating layer, the hairline finish treatment was found to obtain a high corrosion-resistant galvanized steel having a good hairline appearance to complete the present invention It was.

The gist of the present invention is as follows.

(1) the plating adhesion amount is 10 to 600 g / m ² , and has a hairline formed on the surface layer of the plating layer containing 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, the balance being Zn and unavoidable impurities; The hairline has a surface roughness (Ra) of 0.2 to 2.5 µm and a peak number (PPI) of 50 to 400 in a direction perpendicular to the hairline, and a surface roughness (Ra) of 0.1 to 1.2 µm and a number of peaks ( PPI) is 1 to 100, the surface roughness Ra in the direction perpendicular to the hairline is 1.2 times or more of the surface roughness Ra in the hairline direction, and the PPI in the direction perpendicular to the hairline is 2.0 times the PPI in the hairline direction. The highly corrosion-resistant Zn type alloy plating steel material which has the hairline appearance characterized by the above.

(2) the plating adhesion amount is 10 to 600 g / m ² , and has a hairline formed on the surface layer of the plating layer containing 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, the balance being Zn and unavoidable impurities; The hairline has a peak number (PPI) in the direction perpendicular to the hairline of 50 to 400, a peak number PPI in the hairline direction of 1 to 100, and a PPI in the direction perpendicular to the hairline is 2.0 of the PPI in the hairline direction. A highly corrosion-resistant Zn-based alloy plated steel material having a hairline appearance, characterized in that it is twice or more.

(3) the plating adhesion amount is 10 to 600 g / m ² , and has a hairline formed on the surface layer of the plating layer containing 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, the balance being Zn and unavoidable impurities; The hairline has a surface roughness (Ra) of 0.1 to 2.5 μm and a peak number (PPI) of 50 to 400 in a direction perpendicular to the hairline, and has a surface roughness (Ra) of 0.1 to 1.2 μm and a number of peaks ( PPI) is 1 to 100, the surface roughness Ra in the direction perpendicular to the hairline is 1.2 times or more of the surface roughness Ra in the hairline direction, and the PPI in the direction perpendicular to the hairline is 2.0 times the PPI in the hairline direction. The highly corrosion-resistant Zn type alloy plating steel material which has the hairline appearance characterized by the above.

(4) The highly corrosion-resistant Zn-based alloy plated steel material according to any one of (1) to (3), wherein the plating layer further contains 0.001 to 3% by mass of Si.

(5) The hairline according to any one of (1) to (4), wherein the plating layer further contains 0.0001 to 0.1% by mass of Ti and 0.0001 to 0.1% by mass of B. Highly corrosion resistant Zn based alloy plated steel with appearance.

(6) The plating layer is any one of (1) to (5), wherein the binary process of Zn and Al is 1 to 80 vol% in volume ratio, and the ternary process of Zn, Al and ZnMg alloy is 10 in volume ratio. A high corrosion resistance Zn-based alloy plated steel having a hairline appearance, characterized in that from 90% to 90% by volume, and the sum of them is 50% or more.

(7) The highly corrosion-resistant Zn-based alloy plated steel material according to any one of (1) to (6), which has a chromate treatment layer on the surface of the plating layer of 1 to 1000 mg / m ² .

(8) The highly corrosion-resistant Zn system having a hairline appearance according to any one of (1) to (6), which has a chromate-free treated layer containing no chromium on the surface of the plating layer, 1 to 200 mg / m ^2. Alloy plating steels.

(9) The highly corrosion-resistant Zn-based alloy plated steel material according to any one of (1) to (8), wherein the surface has a transparent resin coating layer having a thickness of 0.5 to 100 µm.

(10) The metal according to any one of (1) to (9), wherein one or two or more metals of Co, Fe, Ni, Pt, and Mn are located near the interface between the plating layer surface and the chromate-free treated layer containing no chromium. A highly corrosion-resistant Zn-based alloy plated steel having a hairline appearance, characterized by having an adhesion layer in the form or a hydroxide form of 0.1 to 10 mg / m ² and excellent in blackening resistance in a wet environment.

1 is a diagram showing an outline of hairline finishing.

2 is a view showing the structure of the Zn-based alloy plating layer of the present invention, Figure 2a is a micrograph of the Zn-based alloy plating layer of the present invention, Figure 2b is a schematic diagram of the structure.

3 is a cross-sectional photomicrograph of the surface after polishing a highly corrosion-resistant Zn-based alloy plated steel (Zn-11% Al-3 Mg-0.2Si plating, plating deposition amount: 90 g / m ² ) with # 80 sandpaper after the hairline finish. (Magnification: 1000 times).

Implement the invention  Best embodiment for

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

Steels having a hairline appearance include stainless steels having a hairline finish, but stainless steels are expensive. Therefore, the present inventors focused on zinc-based plated steels having high corrosion resistance, such as stainless steels, and studied hairline finishing of zinc-based plated steels.

When the hairline finish is applied to pure galvanized steel, the hairline is loosened or the hairline collapses, so that a hairline having a good appearance cannot be obtained, and the underlying metal is exposed. In addition, there is a problem that the residue is attached to the polishing belt for hairline finishing, and when left in the air after the hairline finishing, white rust occurs, there is also a problem that the appearance of the hairline is lost.

The reason why such a good hairline cannot be obtained is thought to be due to the fact that the zinc plated layer is about 50 Hv soft in hardness. Therefore, attention was paid to the zinc alloy plating layer containing the hard phase, and the hairline finishing treatment resulted in excellent hairlines with excellent appearance. The zinc alloy plating layer containing a hard layer is a zinc alloy plating layer containing Al and Mg, and a plating layer containing a hard layer of a two-step process of Zn and Al and a three-step process of Zn and Al and a ZnMg alloy. I found this suitable. The components of the plating layer are, by mass%, Al: 1.0 to 60%, Mg: 0.1 to 10%, balance Zn and inevitable impurities, Si: 0.001 to 3.0% for the purpose of improving corrosion resistance, and Ti for the purpose of improving the appearance. You may select and contain 1 type or 2 types of: 0.0001 to 0.1%, B: 0.0001 to 0.1% as needed.

The reason which limited the component of a zinc alloy plating layer is demonstrated.

Al forms a two-step process of hard Zn / Al and a three-way process of Zn / Al / Zn ₂ Mg in the plating layer, improves the corrosion resistance of the plating layer, and suppresses dross generation in the plating bath. There is action. If Al is less than 1.0%, the volume occupancy of the two-step and three-way processes, which become hard phases, is insufficient, resulting in a hairline finish that does not provide a good hairline with excellent appearance, and further reduces corrosion resistance of the plated steel. On the other hand, when Al exceeds 60%, unevenness occurs in the plating surface, so that the plating layer with uniform appearance cannot be obtained, and the effect of improving corrosion resistance is saturated, and at the same time, the sacrificial anticorrosive effect on the underlying metal is lost. Corrosion resistance deteriorates. Therefore, Al content was made into 1.0 to 60%.

 Mg is a component necessary for forming a ternary process, and at the same time, forms a corrosion product on the surface of the plating to improve the corrosion resistance of the plated steel. If the Mg is less than 0.1%, the volume share of the three-way process is insufficient, the hairline finish does not obtain a good hairline with good appearance, and cannot form the corrosion products necessary to improve the corrosion resistance. On the other hand, when Mg exceeds 10%, the plating bath is oxidized by atmospheric contact to generate black oxide (dross), making the plating process difficult, and at the same time, improving the corrosion resistance. Therefore, Mg content was made into 0.1 to 10%.

Si is added as needed in order to improve corrosion resistance and plating adhesion. If the added amount is less than 0.001%, such an effect is not obtained. If the added amount is more than 3.0%, such an effect is saturated, and dross production is increased. Therefore, the Si addition amount is set to 0.001 to 3.0%.

Ti is a component to be added as needed in order to generate precipitation nuclei of the pristine Al phase, to refine the structure, and to improve appearance, and it is necessary to add 0.0001% or more. However, when the content exceeds 0.1%, the solubility in the plating bath is higher than that, and Ti-Al-based precipitates grow, irregularities occur on the surface of the plating layer, and the appearance quality deteriorates. Therefore, Ti is set to 0.0001 to 0.1%.

B has an effect of improving the appearance of plating similarly to Ti, but the effect is not obtained when less than 0.0001%, and when the content exceeds 0.1%, B is set to 0.0001 to 0.1%.

The plating deposition amount is the lower limit because the corrosion resistance decreases at 10 g / m ² or less, and the coating adhesion amount is not preferable because the uniform adhesion of the plating layer deteriorates and flows down at 600 g / m ² or more. . In addition, cracks in the plating layer due to bending and the like tend to occur. Therefore, 600 g / m <^2> was made an upper limit.

2A is a micrograph of the structure of the Zn-based alloy plating layer of the present invention, and FIG. 2B is a schematic diagram of the structure.

As shown in FIG. 2B, the cross-sectional structure of the highly corrosion-resistant Zn-based alloy plating layer composed of, for example, Zn-11% Al-3% Mg-0.2% Si is in the three-way process of [Zn / Al / Zn ₂ Mg]. In the structure of (7), the binary process phase 8 of [Zn / Al] is mixed, and the structure of [Zn ₂ Mg single phase] 9 exists in an island shape.

The ternary process phase has a structure in which a soft Zn and Al phase and a hard Zn ₂ Mg are mixed and dispersed, and exhibits both a viscosity and hardness as a whole structure. When the hairline finish treatment is performed on a plated steel material in which such an image is also present on the surface, the plated surface is easily peeled off from the plated surface by the polishing belt, and the acid line of the hairline is not loosened, resulting in a beautiful hairline. A favorable hairline excellent in an external appearance can be obtained without a deposit.

3 is a cross-sectional micrograph of the surface after # 80 sandpaper polishing of a highly corrosion-resistant Zn-based alloy plated steel (Zn-11% Al-3 Mg-0.2Si plating, plating deposition amount: 90 g / m ² ) subjected to hairline finishing. (Magnification: 1000 times). As shown in FIG. 3, no flow occurs in the grooves of the hairline and has a good appearance.

To obtain a hairline having excellent appearance by subjecting the hairline to a highly corrosion-resistant Zn-based alloy plated steel, the [Zn / Al] binary process has a volume share of 1 to 80 vol% and [Zn / Al / Zn as a structure of the plating layer. ₂ Mg] It is preferable that the three-way process phase exists in 10 to 90 vol% by volume occupancy, and consists of remainder Zn, Zn ₂ Mg alloy, Mg ₂ Si, TiAl ₃ , and the like. [Zn / Al] binary process phases are softer than ternary process phases, but harder than Zn and Al single phases. Therefore, the smaller the volume occupancy, the better the hairline treatment. If it is 90 vol% or more, the whole plating layer softens and hairline property falls, and it is difficult for engineering to make it 1 vol% or less. If the volume ratio of the ternary process is small, the hardness and viscosity characteristics of the plated layer are reduced, and the appearance at the time of the hairline treatment is deteriorated, and debris easily adheres to the abrasive. Therefore, the lower limit of the volume occupancy of the three-way process is 10 vol%. On the other hand, since the Al phase and the Zn ₂ Mg phase are likely to occur in the solidification process of the plating layer, 90 vol% was the upper limit in engineering production. Moreover, when the volume occupancy in the process which combined both fell, the hardness and viscosity of the whole plating layer will fall, and since it became a hairline external appearance defect, it was made into 50% or more.

The thickness of the plating layer suitable for the hairline finish is in the range of 10 to 600 g / m ² , preferably 100 to 500 g / m ^2, of the coating adhesion. If the plating adhesion amount is less than 10 g / m ^{2, the} plating layer is thin, and thus corrosion resistance is insufficient, and the steel material is exposed by the hairline finish. If the plating adhesion amount exceeds 600 g / m ² , the plating layer becomes too thick to make the plating layer uniform in appearance, and the plating layer is easy to peel off, which is not preferable in terms of cost. Therefore, plating adhesion amount was 10-600 g / m <^2> .

As a hairline shape excellent in the appearance formed in the plated steel, the surface roughness in the direction perpendicular to the hairline (C direction) has a surface roughness Ra of 0.2 to 2.5 탆, preferably 1.2 to 1.8 탆 and a peak number PPI of 50 to 400. The surface roughness in the hairline direction (L direction) is Ra: 0.1 to 1.2 µm, preferably 0.5 to 1.0 µm, the number of peaks (PPI) is 1 to 100, and is perpendicular to the hairline (C direction). Ra is 1.2 times or more of Ra in the hairline direction (L direction) (C in Ra / L direction Ra≥1.2), and PPI in the direction perpendicular to the hairline (C direction) is in the hairline direction (L direction). It is preferable to set it as 2 times or more (C direction PPI / L direction PPI≥2) of PPI.

If the surface roughness Ra, the peak number PPI, and the ratio of these in the C and L directions are less than the lower limit, the hairline becomes inconspicuous and loses the meaning of finishing the hairline. On the contrary, if the upper limit of the surface roughness Ra and the peak number PPI in the C and L directions is exceeded, the hairline becomes too rough and does not become a beautiful hairline. Disappears.

Therefore, in the present invention, the shape of the hairline is defined by the surface roughness, the number of peaks, and the ratio thereof. In addition, surface roughness Ra was measured by employ | adopting a reference length of 0.8 mm according to the measuring method prescribed | regulated to JIS B060 (1997). In addition, the peak number (PPI) (Peaks Per Inch) was measured according to the provisions of SAEJ911-1986 with a measurement length of 1 inch, plus and minus width (2H) of 50 μinch between reference levels.

In order to form a hairline that satisfies the requirements of the surface roughness, the number of peaks, and their ratios defined in the present invention, it is preferable to perform hairline finishing using a belt sander (polishing belt) of about # 60 to # 320.

After the hairline finish treatment, the plating layer is preferably subjected to a chromate treatment or a chromate free treatment to be subjected to a primary antirust treatment.

Since galvanized steel is easy to generate | occur | produce white rust, in order to prevent this, after performing a hairline finishing of a plating layer, it performs the primary rust prevention treatment which forms an rustproof coating layer by chromate treatment or chromate free treatment.

In the case of chromate treatment, well-known chromate treatment, for example, the chromate treatment by the chromate treatment liquid containing chromic acid and a reaction promoter as a main component can be applied, and chromate adhesion amount is 1-200 mg / m <^2> .

If the chromate adhesion amount is less than 1 mg / m ^2, sufficient antirust effect is not obtained, and if it exceeds 200 mg / m ² , not only the hairline finish is inconspicuous, but also the rust effect is saturated and economically expensive.

In addition, as in the chromate treatment, the primary antirust treatment can be performed by a known chromate free treatment (non chromate treatment).

The chromate free treatment (non chromate treatment) does not contain hexavalent chromium that is harmful to the environment in the treatment liquid, and includes, for example, a treatment liquid containing a salt of Zr, Ti, etc., a treatment liquid containing a silane coupling agent, and the like. The chromate free process using the chromate pretreatment liquid which were prepared can be applied. In such chromate pretreatment, a chromate pretreatment layer containing no chromium containing Ti, Zr, P, Ce, Si, Al, Li, etc. as a main component is formed, and the adhesion amount is preferably 1 to 1000 mg / m ² . .

If the adhesion amount of chromate-free treatment is less than 1 mg / m ^2, sufficient anti-corrosion effect will not be obtained, and if it exceeds 1000 mg / m ² , hairline finish will not be noticeable. This costs

In addition, when the galvanized steel is subjected to a hairline finish and left in the air, the plating surface is oxidized and becomes black. Black discoloration (black color) makes the hairline finish inconspicuous and damages the appearance of the hairline. In addition, the zinc plating layer tends to be flawed when colliding with a hard object. Therefore, when the transparent resin film layer is formed in the thickness of 0.5-100 micrometers on the plating surface which gave the hairline finish, blackening resistance and abrasion resistance can be improved. The transparent resin film layer can be formed by a conventionally known coating method using a conventionally known organic clear paint. As such an organic clear paint, an acrylic baking clear paint, a urethane clear paint, an epoxy clear paint, a polyester clear paint, a melamine alkyd clear paint, etc. are mentioned specifically ,. Among them, polyester-based and acrylic baking clear paints are preferably used.

As a coating method of an organic clear paint, methods, such as a roll coater method, a curtain coater method, a spray drying method, an electrostatic method, are mentioned specifically ,. In these, the roll coater method and the curtain coater method are preferable.

In order to improve the blackening resistance, it is preferable to form an adhesion layer in one or two or more metal or hydroxide states of Co, Fe, Ni, Pt, and Mn in the vicinity of the interface with the chromate or chromate free treatment layer. The deposition amount of the deposit layer is preferably 0.1 to 10 mg / m ² , preferably 0.5 to 3.0 mg / m ² . By the above treatment, the blackening resistance under the wet environment is greatly improved. If the adhesion amount is 0.1 mg / m ² or less, the effect of blackening resistance is not sufficient, and at 10 mg / m ² or more, deterioration of corrosion resistance occurs, which is not preferable. Although the method of providing the said process layer is not specifically limited, As an example, there exist an immersion method of the said salt aqueous solution, a spray method, a vacuum vapor deposition method, etc. In the immersion method, the plated steel sheet treated with hairline is immersed in 0.1-10 g / L of the corresponding metal salt aqueous solution for 0.5 to 10 seconds, followed by water washing.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example.

Two types of low carbon steel sheets having a plate thickness of 0.8 mm and 1.6 mm were used as the plating original plates.

Plating was carried out by heating, annealing and plating in a continuous hot dip galvanizing line of an anoxic furnace type. The annealing atmosphere formed 10% hydrogen and the remaining 90% nitrogen gas atmosphere to make the dew point at -30 ° C. Annealing temperature is 730 degreeC, and annealing time is 3 minutes. The plating bath composition was composed of Al: 11.0%, Mg: 3.0%, Si: 0.2%, balance Zn, and inevitable impurities in mass%, and the plating bath temperature was 450 占 폚. The plating adhesion amount was adjusted by the usual nitrogen gas wiping method.

After the plating, hairline finishing was carried out using a belt sander (size 100 mm x 915 mm) having a different number, under conditions of a belt speed of about 3.5 / second and a polishing time of 3 to 4 seconds. Then, surface roughness Ra and peak number PPI were investigated.

The results are shown in Table 1.

As shown in Table 1, No. 1, No. 2 and No. 5 satisfy the conditions of the surface roughness (Ra), the number of peaks (PPI) and their ratios defined in the present invention, and have a beautiful hairline appearance. It became a highly corrosion-resistant plated steel.

On the other hand, in No. 3 subjected to the bead blasting treatment of # 80, although uniform fine irregularities were formed on the surface, the surface roughness and the number of peaks in the L direction were small, and the ratio of the surface roughness and the number of peaks was also small. It is not satisfied, and the bead blast treatment and hairline finish are clearly different.

No. 4 had a hairline finish, but the belt sander had a roughness of # 600 so fine that it did not satisfy the requirements of the hairline defined in the present invention, and the appearance of the hairline could not be clearly observed.

In addition, although No.6 and No.7 did not finish a hairline, in this case, the surface roughness and peak number of C direction were small, and their ratio was also small. In this case as well, no hairline was observed.

From the above test result, only the plated steel plate which gave the hairline finish which satisfy | fills the requirements prescribed | regulated by this invention became a plated steel plate which has a beautiful hairline appearance.

Next, after forming and plating the plated steel sheet which changed the composition of the plating layer in various ways, using the belt sander (size 100mm x 915mm) of the number # 80, belt speed about 3.5 / second, grinding time 3 thru | or The hairline finish was done on the conditions of 4 second. At that time, the appearance of the hairline and the adhesion state of the residue were examined.

The results are shown in Table 2. Nos. 1 to 17 had the plating composition defined in the present invention and were good results in any of the appearance of hairline, adhesion of sander residue, and corrosion resistance. On the other hand, Nos. 18 to 20 are platings other than the composition specified in the present invention, and the value of the surface roughness satisfies the value specified in the present invention, but the appearance of the hairline was not clearly observed, and the occurrence of the residue The corrosion resistance was poor. The reason that the appearance of the hairline was not clearly observed is considered to be because of the occurrence of debris and the flow of polishing defects.

Moreover, the plating which changed the volume occupancy in the process in a plating layer was created, and the performance was investigated. The results are shown in Table 3. Nos. 1 to 5 had the phase structure defined in the present invention and were good results in all of the appearance of the hairline, adhesion of sander residue and corrosion resistance. On the other hand, No. 6 and No. 7 were plating other than the phase structure prescribed | regulated by this invention, and the external appearance of a hairline was bad and the generation of waste was bad.

Further, using a plated steel sheet having a composition of Zn-11Al-3Mg-0.2Si, chromate treatment, chromate free treatment, clear coating treatment, and blackening treatment were performed. The chromate treatment was coated with 100 g / L solution of chromic acid, and then dried in a hot stove at 60 ° C. for 30 seconds. The chromate-free treatment was applied with a chemical agent consisting of ammonium zirconium carbonate, cobalt nitrate, silica, and ammonium phosphate, followed by drying for 30 seconds in a hot oven at 60 ° C. Furthermore, the melamine alkyd clear paint (solvent type) and the acrylic clear paint (water dispersion type) were apply | coated and it heated to the board temperature of 220 degreeC (melamine alkyd type) and 150 degreeC (acrylic type). After black immersion treatment was immersed in 1 g / L Ni sulfate solution for 3 seconds, washed with water and dried to give the chromate-free treatment and melamine alkyd clear coating. Evaluation of the corrosion resistance of the flat part was the amount of white rust generated after 240 hours of salt spray test of JIS Z2331, and was determined to be ○: white rust generated 1% or less, ×: 10% or more. The cross cut part was evaluated by the blister width after 1000 hours of the salt spray test, and judged as (circle): less than 2 mm and x: 2 mm or more. The evaluation of the blackening resistance was performed by leaving the treated steel in a high temperature, high humidity tank at 60 ° C. and a relative humidity of 85% for 7 days and evaluating the color difference δE value before and after standing. Measurement of the color difference δE was in accordance with JIS Z8722. When δE was 1 or less, there was no black side, and it was good (○), 1 to 2 were slightly recognized and slightly good (Δ), and when larger than 2, black side was recognized and made into bad (×).

Nos. 1 to 46 satisfy the blackening treatment, pretreatment and coating requirements specified in the present invention, and both the flat portion and the cross cut portion have good corrosion resistance. In addition, No. 23 and No. 46 subjected to blackening resistance were also excellent in blackening resistance. On the other hand, Nos. 47 to 49 were beyond the requirements of the present invention and were poor in corrosion resistance.

Since the highly corrosion-resistant galvanized steel having the hairline appearance of the present invention has a good hairline appearance and excellent corrosion resistance, it can be applied to the same use as that of the stainless steel having the conventional hairline appearance. In addition, it is possible to supply at a lower price than expensive stainless steels.

Claims (10)

The coating amount is 10 to 600 g / m ² , has a hairline formed on the surface layer of the plating layer containing 1 to 60% by mass of Al, 0.1 to 10% by mass of Mg and the balance of Zn and unavoidable impurities, the hairline The surface roughness Ra in the direction perpendicular to the silver hairline is 0.2 to 2.5 µm, the surface roughness Ra in the hairline direction is 0.1 to 1.2 µm, and the surface roughness Ra in the direction perpendicular to the hairline is the hairline direction. A highly corrosion-resistant Zn-based alloy plated steel having a hairline appearance, characterized in that it is 1.2 times or more of the surface roughness (Ra). The coating amount is 10 to 600 g / m ² , has a hairline formed on the surface layer of the plating layer containing 1 to 60% by mass of Al, 0.1 to 10% by mass of Mg and the balance of Zn and unavoidable impurities, the hairline The number of peaks (PPI) in the direction perpendicular to the hairline is 50 to 400, the number of peaks (PPI) in the direction of the hairline is 1 to 100, and the PPI in the direction perpendicular to the hairline is at least 2.0 times the PPI in the direction of the hairline. High corrosion resistance Zn-based alloy plated steel having a hairline appearance. The plating adhesion amount is 10 to 600 g / m ² , contains 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, and the balance has a hairline formed on the surface layer of the plating layer composed of Zn and unavoidable impurities. The hairline has a surface roughness (Ra) of 0.1 to 2.5 μm and a peak number (PPI) of 50 to 400 in a direction perpendicular to the hairline, and a surface roughness (Ra) of 0.1 to 1.2 μm and a peak number (PPI) in the hairline direction. ) Is 1 to 100, and the surface roughness Ra in the direction perpendicular to the hairline is 1.2 times or more of the surface roughness Ra in the hairline direction, and the PPI in the direction perpendicular to the hairline is 2.0 times the PPI in the hairline direction. The highly corrosion-resistant Zn type alloy plating steel material which has the hairline appearance characterized by the above. The method according to any one of claims 1 to 3, Highly corrosion-resistant Zn-based alloy plating steel having a hairline appearance, characterized in that the plating layer further contains 0.001 to 3% by mass of Si. The method according to any one of claims 1 to 3, Highly corrosion-resistant Zn-based alloy plating steel having a hairline appearance, characterized in that the plating layer further contains 0.0001 to 0.1% by mass of Ti and 0.0001 to 0.1% by mass of B. The method according to any one of claims 1 to 3, The plating layer is characterized in that the binary process of Zn and Al is 1 to 80 vol% in volume ratio, and the ternary process of Zn and Al and ZnMg alloy is 10 to 90 vol% in volume ratio, and the sum of both is 50% or more. High corrosion resistance Zn-based alloy plated steel having a hairline appearance. The method according to any one of claims 1 to 3, A highly corrosion-resistant Zn-based alloy plated steel having a hairline appearance, characterized in that it has a chromate treated layer on the surface of the plated layer, 1 to 1000 mg / m ² . The method according to any one of claims 1 to 3, A highly corrosion-resistant Zn-based alloy plated steel having a hairline appearance, characterized by having a chromate-free treated layer containing no chromium on the surface of the plating layer, 1 to 200 mg / m ² . The method according to any one of claims 1 to 3, A highly corrosion-resistant Zn-based alloy plated steel material having a hairline appearance, which has a transparent resin film layer having a thickness of 0.5 to 100 μm on its surface. The method according to any one of claims 1 to 3, One or two or more metal or hydroxide deposits of Co, Fe, Ni, Pt, and Mn in the vicinity of the interface between the surface of the plating layer and the chromate-free treated layer containing no chromium have 0.1 to 10 mg / m ² A high corrosion resistance Zn-based alloy plated steel having a hairline appearance, characterized by excellent blackening resistance in a wet environment.

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