JP2006124824A - HIGHLY CORROSION RESISTANT Zn ALLOY PLATED STEEL MATERIAL HAVING HAIRLINE APPEARANCE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly corrosion resistant zinc alloy plated steel material having a hairline appearance that can find application in the same usages as those of stainless steel material. <P>SOLUTION: There is provided the highly corrosion resistant Zn alloy plated steel material with the hairline appearance, having hairlines formed on a surface layer of plating layer of 10 to 600 g/m<SP>2</SP>plated skin quantity composed of 1 to 60mass% Al, 0.1 to 10mass% Mg and the balance of Zn and unavoidable impurities, which hairlines are characterized in that in the direction perpendicular to the hairlines, the surface roughness Ra is in the range of 0.2 to 2.5 μm and the peak count PPI (number of peaks per inch) in the range of 50 to 400; along the hairline direction, the surface roughness Ra is in the range of 0.1 to 1.2 μm and the peak count PPI in the range of 1 to 100; the surface roughness Ra in the direction perpendicular to the hairlines is ≥1.2 times the surface roughness Ra along the hairline direction; and the PPI in the direction perpendicular to the hairlines is ≥2.0 times the PPI along the hairline direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance used for interior materials and exterior materials such as buildings and vehicles, and surface layer materials for electrical equipment.

  Stainless steel materials are well known as steel materials having a conventional hairline appearance. In other words, hairline finish (HL finish) is defined in JIS G 4305 and 4307 as one of the surface finishes of stainless steel materials, and the hairline finish is “polished with a continuous grain with an abrasive of appropriate particle size. As defined as “finished”, it means a surface finish in which the polished surface is long and continuous like hair.

  FIG. 1 is a diagram showing an outline of hairline finishing.

  In the normal hairline finishing method, as shown in FIG. 1, the endless paper polishing belt 3 stretched between the contact wheel 1 and the idle roll 2 is rotated at a high speed by rotating the contact wheel and moved from the uncoiler 4 to the coiler 5. It is well known that this is a processing method for polishing the surface of the stainless steel material 6 with a polishing belt (for example, see Patent Documents 1 and 2). Stainless steel materials with a hairline finish are corrosion resistant and have a unique surface pattern, so they are widely used in interior materials and exterior materials for building materials where design is important, and surface materials for electrical equipment.

  However, since stainless steel is expensive, it is a new inexpensive material that replaces stainless steel, has high corrosion resistance similar to stainless steel, and has a hairline appearance suitable for use in building materials and electrical equipment. It is.

  Then, this inventor paid attention to the galvanized steel material excellent in corrosion resistance similarly to stainless steel materials, and cheaply, and researched about giving this a hairline finish.

  As a conventional technique for applying a hairline finish to the plating layer, if a plating coating layer is formed on the surface of a thin and light magnesium-based member and a hairline pattern is formed on the surface of the plating coating layer by hairline finishing, As a result, a technique has been proposed that solves the problem that the corrosion resistance deteriorates and a high-quality member cannot be stably obtained.

  That is, on the surface of the Mg-based component, a plating coating layer (1) selected from Cu, Cu alloy, Au, Au alloy, Al, and Al alloy, formed by dry plating, and on the plating coating layer (1) Further, Mg having a plating coating layer (2) selected from Cu, Ni, Au, Cr, Zn, Pa, Pt, Rh, Fe, Co, Sn, Cd, Ru, and alloys thereof formed by a wet plating method. This is a technique for applying a hairline finish to the surface of a system part (for example, see Patent Document 3). However, this technique requires a double thick plating coating layer, and it is necessary to combine the dry plating method and the wet plating method. Have difficulty.

  Various inventions have been made for high corrosion resistance Zn-based alloy-plated steel sheets. For example, Zn-Al-Mg-based alloy-plated steel sheets have mass percentages of Al: 3 to 17%, Mg: 1 to 5%. Further, a plated steel plate using a plating bath made of the remaining Zn, a plated steel plate using a plating bath to which Ti and B are added (for example, see Patent Document 4), or a Zn-Al-Mg-Si alloy In the plated steel sheet, Al: 5 to 8%, Mg: 1 to 10%, Si: 0.01 to 2%, Fe: 1% or less as required, or Sn: 0.00%. A plated steel sheet having a plating layer containing 1 to 2% is known (see, for example, Patent Document 5).

JP-A-1-306162 Japanese Examined Patent Publication No. 7-96183 Japanese Patent Laid-Open No. 2000-219977 Japanese Patent Laid-Open No. 10-306357 Japanese Patent Laid-Open No. 2001-355053

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

  The present inventor has eagerly studied about hairline finishing on a galvanized steel material, which is a material cheaper than stainless steel material and having similar corrosion resistance as a material to replace a stainless steel material having a hairline appearance. As a result, when the hairline finish is applied to pure galvanized steel, since the zinc is soft, the formed hairline is liable to be crushed, and the hairline finishing abrasive belt is easily clogged during processing. It was not obtained and hairline finishing was difficult. Further, the hairline-finished galvanized steel material has white rust on the zinc surface in the atmosphere, and when white rust is generated, the hairline appearance disappears and the effect of forming the hairline is lost.

  Therefore, in the present invention, focusing on high corrosion resistance Zn-based alloy plating containing a hard phase in the plating layer, it was found that high corrosion resistance galvanized steel material having a good hairline appearance can be obtained by applying a hairline finish thereto. The present invention has been completed.

  The gist of the present invention is as follows.

(1) The plating adhesion amount is 10 to 600 g / m ² , Al is contained in 1 to 60% by mass, Mg is contained in 0.1 to 10% by mass, and the balance is formed on the surface layer of the plating layer made of Zn and inevitable impurities. The hairline has a surface roughness Ra in the direction perpendicular to the hairline of 0.2 to 2.5 μm, a peak number PPI of 50 to 400, and a surface roughness Ra in the hairline direction of 0.1 to 1. .2 μm, the 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 the surface roughness Ra in the hairline direction, and the PPI in the direction perpendicular to the hairline is 2. A highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance characterized by being 0 times or more.

  (2) The highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to the above (1), wherein the plating layer further contains 0.001 to 3% by mass of Si.

  (3) The above-mentioned (1), wherein the plating layer further contains one or two of 0.0001 to 0.1% by mass of Ti and 0.0001 to 0.1% by mass of B. Alternatively, a highly corrosion-resistant Zn-based alloy plated steel material having the hairline appearance described in (2).

  (4) As for the plating layer, the binary eutectic of Zn and Al is 1 to 80 vol% in volume occupancy, and the ternary eutectic of Zn, Al and ZnMg alloy is 10 to 90 vol% in volume occupancy. The corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of the above (1) to (3), wherein

(5) the plating layer surface, the characterized by having a chromate treatment layer ^{1~200mg / m 2 (1) ~} (4) high corrosion resistance Zn alloy coated steel material having a hairline appearance according to any one of.

(6) A highly corrosion-resistant Zn-based material having a hairline appearance according to any one of (1) to (4) above, wherein the plating layer has a chromate-free treated layer containing no Cr in an amount of 1 to 1000 mg / m2. Alloy plated steel.
The highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of the above (1) to (6), which has a transparent resin film layer having a thickness of 0.5 to 100 μm on the surface.
In the vicinity of the interface between the plating layer surface and the chromate-free treatment layer not containing chromium, one or more of Co, Fe, Ni, Pt, and Mn, or an adhering layer in the metal state or hydroxide state is 0.1 to 2 The highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of 1 to 7 above, which has 10 mg / m ² and is excellent in blackening resistance in a wet environment.

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

  The present invention will be described in detail below.

  As a steel material having a hairline appearance, there is a stainless steel material subjected to a hairline finish, but the stainless steel material is expensive. Therefore, the present inventors paid attention to a zinc-based plated steel material having high corrosion resistance similarly to a stainless steel material, and studied the hairline finishing on the zinc-based plated steel material.

  When a pure galvanized steel material is subjected to a hairline finish, the ridges of the hairline sag or the hairline is crushed so that a hairline having a good appearance cannot be obtained, and there are portions where the bare metal is exposed. In addition, there is a problem that the hairline finishing polishing belt is clogged, and further, there is a problem that when the hairline finish is left in the atmosphere after finishing the hairline, white rust is generated and the hairline appearance disappears.

  The reason why such a good hairline cannot be obtained is considered to be due to the fact that the galvanized layer has a hardness of about 50 Hv and is soft. Then, paying attention to the zinc alloy plating layer containing the hard phase and applying hairline finishing to this, a good hairline excellent in appearance could be obtained. The zinc alloy plating layer containing the hard layer is a zinc alloy plating layer containing Al and Mg, and includes a binary eutectic of Zn and Al and a combination of Zn, Al and ZnMg alloy. It has been found that a plating layer containing an eutectic hard layer is suitable. The component of the plating layer is mass%, Al: 1.0 to 60%, Mg: 0.1 to 10%, the balance Zn and unavoidable impurities and a plating layer containing Si: 0 for the purpose of improving corrosion resistance. 0.001 to 3.0%, and for the purpose of improving the appearance, one or two of Ti: 0.0001 to 0.1% and B: 0.0001 to 0.1% are selected and contained as necessary. May be.

  The reason for limiting the components of the zinc alloy plating layer will be described.

Al forms a hard phase Zn / Al binary eutectic and Zn / Al / Zn ₂ Mg ternary eutectic in the plating layer, improves the corrosion resistance of the plating layer, and in the plating bath. It has the effect of suppressing dross generation. If the Al content is less than 1.0%, the volume occupancy of the binary eutectic and ternary eutectic that forms the hard phase is insufficient, and a good hairline with an excellent appearance cannot be obtained with a hairline finish. The corrosion resistance of is inferior. On the other hand, if Al exceeds 60%, sink-like irregularities occur on the plating surface, and the appearance cannot be made uniform, and the corrosion resistance improving effect is saturated and at the same time the sacrificial anticorrosive action on the base iron disappears, Corrosion resistance of the buttocks deteriorates. Therefore, the Al content is set to 1.0 to 60%.

  Mg is a component necessary for forming a ternary eutectic, and has an effect of improving the corrosion resistance of the plated steel material by forming a corrosion product on the plating surface. If Mg is less than 0.1%, the volume occupancy of the ternary eutectic is insufficient, and a good hairline with an excellent appearance cannot be obtained with a hairline finish, and a corrosion product necessary for improving corrosion resistance is formed. I can't let you. On the other hand, if Mg exceeds 10%, the plating bath is oxidized by contact with the atmosphere to produce black oxide (dross), making the plating process difficult, and the effect of improving corrosion resistance is saturated. Therefore, the Mg content is set to 0.1 to 10%.

  Si is added as necessary to improve corrosion resistance and plating adhesion. If the addition amount is less than 0.001%, these effects cannot be obtained. If the addition amount exceeds 3.0%, these effects are saturated and dross generation is increased. 0.0%.

  Ti is a component that is added as necessary to generate precipitation nuclei of the primary Al phase, refine the structure, and improve the appearance, and needs to be added in an amount of 0.0001% or more. However, if added over 0.1%, the solubility in the plating bath is exceeded, Ti-Al based precipitates grow, the surface of the plating layer becomes uneven, and the appearance quality deteriorates. 0001-0.1%.

  B has an effect of improving the appearance of plating similarly to Ti, but if less than 0.0001%, the effect cannot be obtained, and if over 0.1%, the effect is saturated. 0.1%.

The plating adhesion amount is lower because corrosion resistance is inferior at 10 g / m ² or less, and at 600 g / m ² or more, the uniform adhesion of the plating layer is deteriorated and a sagging appearance is not preferable. Cracking is likely to occur. Therefore, the upper limit was set to 600 g / m ² .

  FIG. 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. 2, the cross-sectional structure of a highly corrosion-resistant Zn-based alloy plating layer made of, for example, Zn-11% Al-3% Mg-0.2% Si is ternary [Zn / Al / Zn ₂ Mg]. In the structure of the crystal phase 7, the [Zn / Al] binary eutectic phase 8 is mixed, and the [Zn ₂ Mg single phase] 9 is in an island shape.

This ternary eutectic phase has a structure in which a soft Zn and Al phase and hard Zn ₂ Mg are complexed and dispersed, and the entire structure exhibits the characteristics of having both stickiness and hardness. When the hairline finish is applied to the plated steel material in which such a phase is also present on the surface, the plated surface is easily peeled off from the plated surface by the polishing belt, and the hairline becomes a beautiful hairline without causing sag, In addition, a good hairline excellent in appearance can be obtained without causing clogging of the polishing belt.

FIG. 3 shows a cross section of the surface after a high-corrosion resistance Zn-based alloy plated steel material (Zn-11% Al-3Mg-0.2Si plating, plating weight: 90 g / m ² ) subjected to hairline finishing is # 80 emery polished. It is a microscope picture (magnification: 1000 times). As shown in FIG. 3, it has a good appearance without causing a sag in the hairline groove.

In order to obtain a hairline excellent in appearance by applying a hairline finish to a highly corrosion-resistant Zn-based alloy-plated steel material, the structure of the plated layer is [Zn / Al] binary eutectic phase in a volume occupancy of 1 to 80 vol%, _{[Zn / Al / Zn 2 Mg} ] Sangentomo phase is present 10～90Vol% by volume occupancy, the balance Zn, Zn ₂ Mg alloy, Mg ₂ Si, is preferably a tissue comprising _three like TiAl. The [Zn / Al] binary eutectic phase is soft compared to the ternary eutectic phase, but hard compared to the Zn and Al single phase. Therefore, the hairline processability improves as the volume occupancy decreases. If it is 90 vol% or more, the whole plating layer is softened, the hairline property is inferior, and it is engineeringly difficult to make it 1 vol% or less. When the volume ratio of the ternary eutectic is reduced, the hardness and stickiness characteristics of the plating layer are reduced, the appearance at the time of hairline treatment is deteriorated, and clogging of the abrasive due to debris is likely to occur. Therefore, the lower limit of the volume occupancy of the ternary eutectic is 10 vol%. On the other hand, the upper limit is that an Al phase or a Zn ₂ Mg phase is easily generated in the process of solidification of the plating layer, and 90 vol% was the upper limit in engineering production. Moreover, when the volume occupation rate of the eutectic phase which combined both falls, the hardness and viscosity of the whole plating layer will fall, and the hairline external appearance will become defect, Therefore It was set as 50% or more.

The thickness of the plating layer suitable for performing the hairline finishing, coating weight is 10~600g / m ^2, preferably in the range of 100 to 500 g / m ^2. If the plating adhesion amount is less than 10 g / m ² , the plating layer is thin, so that the corrosion resistance is insufficient, and the steel substrate is exposed by hairline finishing. When 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 easily peeled off, which is not preferable from the viewpoint of cost. Therefore, the plating adhesion amount is set to 10 to 600 g / m ² .

  As the hairline shape with excellent appearance formed on the plated steel material, the surface roughness in the direction perpendicular to the hairline (C direction) is the surface roughness Ra: 0.2 to 2.5 μm, preferably 1.2 to 1. 8 μm peak number PPI: 50 to 400 and hairline direction (L direction) surface roughness Ra: 0.1 to 1.2 μm, preferably 0.5 to 1.0 μm and peak number PPI 1 to 100 And Ra in the direction perpendicular to the hairline (C direction) is 1.2 times or more of Ra in the hairline direction (L direction) (C direction Ra / L direction Ra ≧ 1.2), and the hairline perpendicular direction (C direction) ) Is preferably at least twice the PPI in the hairline direction (L direction) (C direction PPI / L direction PPI ≧ 2).

  If the surface roughness Ra in the C direction and the L direction defined by these, the number of peaks PPI, and the ratio thereof are less than the lower limit, the hairline becomes inconspicuous and the hairline finish is wasted. On the other hand, if the upper limit of the surface roughness Ra and peak number PPI in the C direction and L direction is exceeded, the hairline becomes too rough, and it is not a beautiful hairline and the design as a hairline is impaired. The value is lost.

  Therefore, in the present invention, the shape of the hairline is defined by the surface roughness, the number of peaks, and the ratio thereof as described above. The surface roughness Ra was measured by adopting a reference length of 0.8 mm in accordance with a measurement method defined in JIS B060 (1997). The number of peaks PPI (Peaks Per Inch) was measured according to the regulations of SAEJ 911-1986, with a measurement length of 1 inch and a width 2H between positive and negative reference levels of 50 μinch.

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

  After the hairline finish, it is preferable to perform primary rust prevention treatment by subjecting the plating layer to chromate treatment or chromate-free treatment.

Since galvanized steel materials are prone to white rust, after the hairline finish is applied to the plating layer, the primary rust prevention treatment is performed to form a rust-proof coating layer by chromate treatment or chromate-free treatment. .
In the case of chromate treatment, a known chromate treatment, for example, a chromate treatment with a chromate treatment solution containing chromic acid and a reaction accelerator as main components can be applied, and the chromate adhesion amount is set to 1 to 200 mg / m ² . .

If the chromate adhesion amount is less than 1 mg / m ² , sufficient rust prevention effect cannot be obtained, and if it exceeds 200 mg / m ² , the hairline finish not only becomes inconspicuous, but the rust prevention effect is saturated and economically. Cost increases.

  Similarly to the chromate treatment, the primary rust prevention treatment can also be performed by a known chromate-free treatment (non-chromate treatment).

Chromate-free treatment (non-chromate treatment) does not contain environmentally harmful hexavalent chromium in the treatment liquid. For example, there are treatment liquids containing Zr and Ti salts, treatment liquids containing silane coupling agents, etc. A chromate-free treatment using a known chromate-free treatment solution can be applied. In these chromate-free treatments, a chromium-free chromate-free treatment layer containing Ti, Zr, P, Ce, Si, Al, Li, etc. as a main component is formed, and the adhesion amount is 1 to 1000 mg / m ^2. Is preferred.

If the amount of chromate-free treatment is less than 1 mg / m ² , a sufficient rust prevention effect will not be obtained, and if it exceeds 1000 mg / m ² , the hairline finish will not be noticeable and the rust prevention effect will be saturated. Costly.

  Moreover, when a galvanized steel material is subjected to a hairline finish and left in the air, the plating surface is oxidized and turned black. If the color changes to black (black change), the hairline finish becomes inconspicuous and the appearance of the hairline is impaired. The galvanized layer is prone to wrinkles when it collides with a hard object. For this reason, if a transparent resin film layer is formed in the thickness of 0.5-100 micrometers on the plating surface which gave the hairline finish, blackening-proof property and a scratch resistance can be improved. The transparent resin coating layer can be formed by a conventionally known coating method using a conventionally known organic clear paint. Specific examples of such organic clear paints include acrylic baking clear paints, urethane clear paints, epoxy clear paints, polyester clear paints, and melamine alkyd clear paints. Of these, polyester-based and acrylic-based clear paints are preferably used.

  Specific examples of the coating method of the organic clear paint include a roll coater method, a curtain coater method, a spray gun method, and an electrostatic method. Among these, the roll coater method and the curtain coater method are preferable.

In order to improve blackening resistance, when an adhesion layer of one or more of Co, Fe, Ni, Pt, and Mn or two or more metal states or hydroxide states is provided in the vicinity of the interface with the chromate or chromate-free treatment layer. good. The adhesion layer has a good adhesion amount of 0.1 to 10 mg / m ² , preferably 0.5 to 3.0 mg / m ² . This treatment greatly improves the resistance to blackening in a wet environment. If the adhesion amount is 0.1 mg / m ² or less, the effect of blackening resistance is not sufficient, and if it is 10 mg / m ² or more, the corrosion resistance deteriorates, which is not desirable. A method for applying the treatment layer is not particularly limited, and examples thereof include a dipping method, a spray method, a vacuum deposition method, and the like of the salt aqueous solution. In the dipping method, the plated steel sheet subjected to the hairline treatment is immersed in the aqueous metal salt solution of 0.1 to 10 g / L for 0.5 to 10 seconds and then washed with water.

  Hereinafter, the present invention will be described in detail based on examples.

  Two types of low-carbon steel plates having thicknesses of 0.8 mm and 1.6 mm were used as the plating original plates.

  Plating was performed by heating, annealing, and plating in a non-oxidizing furnace type continuous hot dip galvanizing line. The annealing atmosphere enclosed 10% hydrogen and the remaining 90% nitrogen gas atmosphere, and the dew point was −30 ° C. The annealing temperature is 730 ° C., and the annealing time is 3 minutes. The plating bath composition was mass%, consisting of Al: 11.0%, Mg: 3.0%, Si: 0.2%, the balance Zn and unavoidable impurities, and the plating bath temperature was 450 ° C. The amount of plating was adjusted by the usual nitrogen gas wiping method.

  After plating, hairline finishing was performed using a belt sander (size 100 mm × 915 mm) with a different count under conditions of a belt speed of about 3.5 / second and a polishing time of 3 to 4 seconds. Thereafter, the surface roughness (Ra) and the number of peaks (PPI) were examined.

  The results are shown in Table 1.

  As shown in Table 1, no. 1, 2 and 5 satisfy the conditions of surface roughness (Ra), peak number (PPI) and their ratio defined in the present invention, and have become highly corrosion-resistant plated steel materials having a beautiful hairline appearance.

  On the other hand, No. 80 which performed # 80 bead blasting treatment. No. 3 had uniform fine irregularities formed on the surface, but the surface roughness in the L direction and the number of peaks were small, and the ratio of the surface roughness and the number of peaks was also small, satisfying the requirements specified in the present invention. No, the bead blasting and the hairline finish were clearly different.

  No. No. 4 was subjected to hairline finishing, but the belt sander was # 600 and the roughness was too fine, did not satisfy the requirements of the hairline defined in the present invention, and the hairline could not be clearly observed in appearance.

  No. 6 and no. 7 is a case where hairline finishing was not performed. In this case, the surface roughness in the C direction and the number of peaks were small, and the ratio thereof was also small. In this case, naturally, no hairline was observed.

  From the above test results, only a plated steel sheet with a hairline finish that satisfies the requirements defined in the present invention was a plated steel sheet having a beautiful hairline appearance.

  Next, a plated steel sheet with various changes in the composition of the plating layer was prepared, and after plating, a belt sander (size 100 mm × 915 mm) with a count # 80 was used, with a belt speed of about 3.5 / second, a polishing time of 3 Hairline finishing was performed under conditions of 4 seconds. At that time, the appearance of hairline and the state of adhesion of dregs were investigated.

  The results are shown in Table 2. No. 1-17 have the plating composition prescribed | regulated by this invention, and were a result with favorable in any of hairline external appearance, the haze of a sander, ie, corrosion resistance. On the other hand, no. 18 to 20 are platings other than the composition defined by the present invention, and the surface roughness value satisfies the value defined by the present invention, but the appearance of the hairline cannot be clearly observed, and the occurrence of debris and corrosion resistance are poor. Met. The reason why the appearance of the hairline could not be clearly observed is thought to be due to the occurrence of debris, dripping of polishing wrinkles, and the like.

  Furthermore, the plating which changed the volume occupation rate of the eutectic phase in a plating layer was created, and the performance was investigated. The results are shown in Table 3. No. 1-5 had the phase structure prescribed | regulated by this invention, and were a result with favorable in any of hairline external appearance, a sander's haze, ie, corrosion resistance. On the other hand, no. 6 and 7 are platings other than the phase structure defined by the present invention, the appearance of the hairline was inferior, and the generation of flaws was poor.

  Furthermore, the chromate process, the chromate free process, the clear coating process, and the blackening-proof process were performed using the plated steel plate which has a composition of Zn-11Al-3Mg-0.2Si. In the chromate treatment, a chromic acid 100 g / l solution was applied and then dried in a hot air oven at 60 ° C. for 30 seconds. In the chromate-free treatment, a chemical agent consisting of ammonium zirconium carbonate, cobalt nitrate, silica, and ammonium phosphate was applied and then dried in a hot air oven at 60 ° C. for 30 seconds. Further, a melamine alkyd clear paint (solvent type) and an acrylic clear paint (water dispersion) were applied and heated to plate temperatures of 220 ° C. (melamine alkyd type) and 150 ° C. (acrylic type). The blackening resistance treatment was immersed in a 1 g / L Ni sulfate aqueous solution for 3 seconds, then washed with water and dried, and then subjected to the chromate-free treatment and melamine alkyd clear coating. The evaluation of the corrosion resistance of the flat surface part was judged by the amount of white rust generated after 240 hours of the salt spray test of JIS Z2331, where ○: white rust was 1% or less, and x: 10% or more. The cross-cut portion was evaluated by the blister width after 1000 hours of the salt spray test, and judged by ○: less than 2 mm and x: 2 mm or more. The blackening resistance was evaluated by allowing the treated steel material to stand in a high-temperature and high-humidity tank at 60 ° C. and 85% relative humidity for 7 days, and evaluating the color difference δE value before and after the standing. The color difference δE was measured according to JIS Z8722. When δE is 1 or less, there is no blackening (good), 1 to 2 are slightly recognized (slightly good), and when it is larger than 2, blacking is recognized and defective (x).

  No. Nos. 1 to 46 satisfied the blackening resistance treatment, pretreatment and coating requirements defined in the present invention, and both the flat portion and the cross cut portion had good corrosion resistance. Furthermore, no. 23 and 46 were also excellent in blackening resistance. On the other hand, no. 47-49 was outside the requirements of the present invention and the corrosion resistance was poor.

It is a figure which shows the outline | summary of a hairline finish. It is sectional drawing which shows the structure | tissue of the Zn type alloy plating layer of this invention typically. Cross-sectional micrograph of the surface after # 80 emery polishing of a highly corrosion-resistant Zn-based alloy plated steel material (Zn-11% Al-3Mg-0.2Si plating, plating weight: 90 g / m ² ) subjected to hairline finish : 1000 times).

Explanation of symbols

1 Contact wheel 2 Idle roll 3 Polishing belt 4 Uncoiler 5 Coiler 6 Stainless steel plate 7 [Zn / Al / Zn ₂ Mg] ternary eutectic phase 8 [Zn / Al] binary eutectic phase 9 [Zn ₂ Mg single phase]

Claims (10)

Hairline formed on the surface of the plating layer with a plating adhesion amount of 10 to 600 g / m ² , containing 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, and the balance being Zn and inevitable impurities The hairline has a surface roughness Ra in the direction perpendicular to the hairline of 0.2 to 2.5 μm, a surface roughness Ra in the direction of the hairline of 0.1 to 1.2 μm, and a surface perpendicular to the hairline. Roughness Ra is 1.2 times or more of surface roughness Ra of a hairline direction, High corrosion-resistant Zn type alloy plating steel materials which have a hairline appearance characterized by the above-mentioned. Hairline formed on the surface of the plating layer with a plating adhesion amount of 10 to 600 g / m ² , containing 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, and the balance being Zn and inevitable 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 direction of the hairline of 1 to 100, and the PPI in the direction perpendicular to the hairline is 2.0 times the PPI in the direction of the hairline. A highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance characterized by the above. Hairline formed on the surface of the plating layer with a plating adhesion amount of 10 to 600 g / m ² , containing 1 to 60% by mass of Al and 0.1 to 10% by mass of Mg, and the balance being Zn and inevitable impurities The hairline has a surface roughness Ra in the direction perpendicular to the hairline of 0.1 to 2.5 μm, a peak number PPI of 50 to 400, and a surface roughness Ra in the hairline direction of 0.1 to 1.2 μm. The 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 the surface roughness Ra in the hairline direction, and the 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 by being at least double.   The highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of claims 1 to 3, wherein the plating layer further contains 0.001 to 3 mass% of Si.   The meditation layer further contains one or two of 0.0001 to 0.1% by mass of Ti and 0.0001 to 0.1% by mass of B. A highly corrosion-resistant Zn-based alloy-plated steel material having the hairline appearance described in any one of the above.   As for the plating layer, the binary eutectic of Zn and Al is 1 to 80 vol% by volume, the ternary eutectic of Zn, Al and ZnMg alloy is 10 to 90 vol% by volume, and the total of both is 50% or more. A highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of claims 1 to 5. The plating layer surface, high corrosion resistance Zn alloy coated steel material having a hairline appearance according to any one of claims 1 to 6, characterized in that the chromate treatment layer has 1 to 1000 mg / m ^2. The plating layer surface, high corrosion resistance Zn alloy coated steel material having a hairline appearance according to any one of claims 1 to 6, characterized in that the chromate-free treatment layer containing no chromium having 1 to 200 mg / m ^2.   The highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of claims 1 to 8, wherein the surface has a transparent resin film layer having a thickness of 0.5 to 100 µm. In the vicinity of the interface between the plating layer surface and the chromate-free treatment layer not containing chromium, one or more of Co, Fe, Ni, Pt, and Mn, or an adhering layer in the metal state or hydroxide state is 0.1 to 2 The highly corrosion-resistant Zn-based alloy-plated steel material having a hairline appearance according to any one of claims 1 to 9, characterized by having 10 mg / m ² and being excellent in blackening resistance in a wet environment.

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