JP2001214280A - Sn SERIES AND Al SERIES PLATED STEEL SHEET COATED WITH Cr- FREE FILM EXCELLENT IN LUBRICITY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain Sn series and Al series plated steel sheets coated with Cr-free post-treated films excellent in lubricity. SOLUTION: (1) The surface of Sn, Sn alloys, Al or Al alloys is coated with a Cr-free post-treated film containing a lubricant of Si of 10 to 1,000 mg/m2 expressed in terms of SiO2 and P and C, desirably, of the film quantity of 1 to 20 wt.%. (2) The post-treated film is incorporated with one or more kinds of the salts of Ni, Zn, Al, Mg, Ti, Co, Mn, Sn, Fe and Zr by a ratio of 0.01 to 0.5 to the quantity of SiO2 as the total of the quantity expressed in terms of the metal. (3) The Sn series plated layer has a composition containing one or two kinds of 3 to 50% Zn and 0.1 to 10% Mg. (4) The Al series plated layer has a composition containing one or more kinds among 3 to 15% Si, 0.1 to 15% Mg and 1 to 30% Zn.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-treated steel sheet which is excellent in press workability and does not use non-environmental substances such as Pb and Cr.

[0002]

2. Description of the Related Art Automotive fuel tank materials, home appliances,
In the field of electronic components, etc., materials that are excellent in soldering, brazing properties, resistance welding properties, and corrosion resistance are required.
N-plated steel sheets (turn-plated steel sheets) have been widely used. However, in recent years, awareness of environmental issues has increased, and regulations on Pb have been increasing. In response to this trend, a wide variety of products are being developed as materials for Pb-free automotive fuel tanks, including hot-dip aluminized steel sheets and hot-dip Sn-Zn coated steel sheets. On the other hand, in the field of electric and electronic parts, for example, a solderable electrogalvanized steel sheet has been developed. However, most of these products which should be replaced with turn plating have been subjected to a chromate treatment on the outermost layer.

[0003]

As is well known, hexavalent chromium is harmful to humans, such as being carcinogenic, and is undesirable because of the possibility of elution from the product or the problem of waste liquid treatment during production. It is. Some products, such as electrolytic chromate, are treated with trivalent chromium, but this product also uses hexavalent chromium at the time of manufacture, and has a problem in terms of waste liquid treatment. However, at present, there is no inexpensive treatment having various performances that can substitute for chromate.

[0004] Naturally, research on post-treatment without using chromium,
Many things have been done. However, in terms of corrosion resistance, paintability, simplicity of processing equipment, etc., a process comparable to chromate has not yet been completed. As one concept, there may be treatment utilizing an organic resin containing an inorganic pigment.However, especially for fuel tank materials, resistance weldability such as spot and seam weldability is required. There is a problem that it is difficult to satisfy these characteristics in an organic treatment having a large thickness. In addition, Sn and Al are themselves excellent in corrosion resistance,
In many cases, the integrity of the plating layer is not maintained for the galling portion during pressing, and there is a concern that the corrosion resistance is not sufficiently exhibited.

[0005]

SUMMARY OF THE INVENTION The present invention is based on the idea that corrosion resistance is basically ensured by a plating metal such as Sn or an Al-based plating layer itself. However, in order to suppress the press flaws and to secure the joining property and the coating property, the structure has been studied so that the post-treatment film has the function. Naturally, Pb and Cr, which are the aim of this study, are plating types that do not use them at all, and a post-treatment film was selected.

Hereinafter, the present invention will be described in detail. The post-treatment film of the present invention is basically a silane coupling agent, at least one Si compound selected from colloidal silica of silica and silicate, a component based on phosphoric acid,
An organic resin component that does not significantly impair weldability and solderability and a lubricant such as polyethylene or silicon WAX that improves the inflow of a steel sheet during press working are added. This film can be optimized depending on the required properties.When solderability and weldability are emphasized, the resin component should be reduced.When bare corrosion resistance and high workability are emphasized, the resin component should be reduced. It is preferable to add a large amount.

First, a description will be given of a film configuration that emphasizes solderability and weldability. Although the thickness of the film cannot be increased due to the importance of bonding, it does not contribute much to long-term bare corrosion resistance, but short-term bare corrosion resistance or bare corrosion resistance in a weakly corrosive environment is improved. In addition, it has excellent paint adhesion and improves corrosion resistance after painting. Further, due to the effect of the addition of the lubricant, it is possible to withstand processing with a drawing ratio of about 2.1. The adhesion amount is 10 to 1000 mg / m ^{2 in} terms of silica. 10 mg / m ²
In the following, since the bare corrosion resistance improving effect, the paint adhesion improving effect, and the lubricant holding function are insufficient, the press galling resistance suppressing effect cannot be obtained. On the other hand, if the adhesion amount is too large,
Has a bad effect on weldability. Therefore, the amount of adhesion is limited to this range.

The particle size of the silica is not limited, but a commonly used average particle size of 1 to 100 μm colloidal silica can be used. Also, the amounts of P and C are not particularly limited, but P is preferably about 0.1 to 1 with respect to the amount of silica, and C is preferably 0.3 or less with respect to the amount of silica. By using phosphoric acid, polyphosphoric acid, a metal compound thereof, or phosphonic acid or a compound thereof as P, paint adhesion is further improved.

The base component is as described above. By adding a metal salt to the base component, an effect of improving paint adhesion can be obtained. Ni, Zn, Al, Mg,
It is preferable to use one or more salts of Ti, Co, Mn, Sn, Fe, and Zr, and the amount of the salt is 0.01 to 0.5 based on the amount of silica as the total amount in terms of metal. By doing so, more excellent characteristics can be obtained. If the content of these salts is too small, a sufficient paint adhesion effect cannot be obtained, and if the content is too large, the stability of the liquid is impaired, and the liquid is easily gelled, or the film is colored and the appearance is deteriorated. The result is impairment. As the kind of the metal salt, Ni-based,
Alternatively, these applications are desirable because Zn-based materials have obtained the best results.

[0010] The kind of the lubricant is not particularly limited. There is no adverse effect when a lubricant is added to the above-mentioned processing solutions. The lubricant has a behavior of being extruded to the outermost layer when the film is cured. Since the lubricant does not react with the film material, when the resin film starts to cure from the lower layer, it will eventually be extruded to the surface layer. When the lubricant is enriched in the surface layer, press workability is improved. The addition amount must be 1 wt% or more based on the amount of the film. Although it depends on the working ratio, the lubricating effect is less likely to be exhibited at less than 1 wt%. Conversely, if the content exceeds 20% by weight, the effect is saturated. Therefore, from the viewpoint of economy, the content is preferably 20% by weight or less. The kind of the lubricant referred to in the present invention is not particularly limited. For example, there are ester type, polyethylene wax type, stearic acid type, silicon type, paraffin wax type, special olefin type and the like.

Next, a description will be given of a film configuration in which the naked corrosion resistance is emphasized. At this time, a composite film of an inorganic component and an organic component is formed. The inorganic component is mainly a Si compound, and preferably 10 to 40% in terms of SiO ₂ in the film.
It is preferable that the 10-400 mg / m ² in ₂ equivalent. If the SiO ₂ content is less than 10%, the corrosion resistance and weldability are reduced, and if it exceeds 40%, the coating adhesion is reduced. Also,
When the coating amount of SiO ₂ is less than 10 mg / m ² ,
Bare corrosion resistance, no paint adhesion, 400mg
/ M ² , solderability and weldability are reduced. Therefore S
The iO ₂ content ratio and the amount of deposition are limited to this range.
The particle size of the silica to be blended is not particularly limited,
A commonly used colloidal silica having an average particle size of 6 to 100 μm can be used.

By adding a metal salt as an inorganic component in addition to the above-mentioned Si compound, bare corrosion resistance and weldability are improved. As metal salts, Sn, Zn, Al, Ni, Co,
At least one metal salt selected from the group consisting of Fe, Ti, and Zr is preferable, and it is added as a water-soluble salt such as phosphate, acetate, nitrate, sulfate, carbonate, chloride, fluoride, and complex fluoride. Is preferred. From 0.01 to 0 with respect to SiO ₂ in a total amount of the amount of content of the metal salt is converted to metal.
It is preferably 1. If it is less than 0.01, the effect of improving corrosion resistance and weldability cannot be obtained, and if it exceeds 0.1, the stability of the treatment liquid is reduced and gelation occurs, the film is colored and the appearance is damaged, and the film becomes brittle. Is not preferred.

Further, it is preferable that phosphoric acid is contained as an inorganic component, whereby the corrosion resistance is improved. The amount of phosphoric acid is preferably from 0.1 to 1.0 with respect to the amount of silica. If it is less than 0.1, the effect of improving corrosion resistance cannot be obtained, and if it exceeds 1.0, the coating adhesion is undesirably reduced. Phosphoric acid
Phosphoric acid, polyphosphoric acid, and their metal salts and ammonium salts are added. As the organic component, use of a phenol resin having a cationic amino group is preferable because bare corrosion resistance, coating adhesion, and treatment liquid stability can be obtained. The phenolic resin having a cationic amino group is not particularly limited. For example, Hitachil 7102, 7103, 7104 manufactured by Hitachi Chemical Co., Ltd.
Phenolite PE-6 manufactured by Dainippon Ink and Chemicals, Inc.
02 and the like. The lubricant components are as described above.

Next, regarding the composition of the plating layer, when Sn is used as a base, Zn: 3 to 50%, Mg: 0.1
Those containing one or two or more of 10% to 10% are preferable. The purpose of the Zn addition is to provide a sacrificial anticorrosion action to the plating layer. If Zn is less than 3%, it is difficult to obtain this effect. On the other hand, when the amount of Zn increases, the occurrence of white rust of Zn increases. When Zn exceeds 50%, white rust is remarkably generated, and this point is preferably set as the upper limit. As the impurity element, there may be trace amounts of Fe, Ni, Co, and the like. In addition, Mg
The effect of improving corrosion resistance can also be obtained by adding. Further, if necessary, Al, misch metal, Sb and the like may be added.

Although there is no particular limitation on the method for producing the Sn-based plated steel sheet, the hot-dip plating method is preferred because it is easy to obtain a thicker coating. As the hot-dip plating process, there are a sendzimer method and a flux method, but there is no particular limitation on the production method. However, in order to obtain a good appearance by Sn-based plating with a high Sn composition, it is preferable to perform Ni, Co-based pre-plating. This facilitates good plating without non-plating. At this time, at the interface between the Sn—Zn (—Mg) plating layer and the substrate, a Ni, Co plating layer, an intermetallic compound layer containing Sn, Zn, and Mg containing these, or a layer composed of a composite of both. Is generated. The thickness of this layer is not particularly limited, but is usually 1 μm or less.

The amount of Sn-based plating affects the characteristics and the manufacturing cost. Naturally, it is preferable that the amount of adhesion be large for corrosion resistance, and that the amount of adhesion be small for spot weldability and cost. The balance of these amounts is about 15 to 50 g / m ^{2 on} one side, and is preferably within this range. For example, when the corrosion resistance of household appliances and the like is not so required, the amount of adhesion is preferably small, and a larger amount is desirable for use in an automobile fuel tank in which corrosion resistance is important. The post-treatment film according to the present invention has less influence on solderability than conventional chromate, and can obtain better solderability than conventional chromate film.

Next, the reasons for limiting the plating layer when using an Al-based base will be described. First, the composition is preferably based on Al and containing 3 to 15% of Si.
The purpose of this Si addition is to suppress excessive growth of the alloy layer, which is a problem in Al-based plated steel sheets. Si is 3%
If it is less than 1, the alloy layer grows too much and the corrosion resistance after molding is reduced. On the other hand, if the amount of Si is too large, coarse primary crystals of Si are crystallized to lower the corrosion resistance. If the Si content exceeds 15%, white rust is likely to occur, and this point is preferably set as the upper limit. As the impurity element, there may be trace amounts of Fe, Ni, Co, and the like.

Further, the effect of improving the corrosion resistance can be further obtained by adding 0.1 to 15% of Mg. By adding both Si and Mg, Mg ₂ Si is generated in the plating layer, and the elution effect also provides an effect of significantly improving corrosion resistance. Although the corrosion resistance of the Al-based plating layer is greatly improved by adding Mg, Zn may be further added for the purpose of suppressing the generation of red rust on the sheared end face. If the amount of addition is less than 1% by weight of the plating adhesion amount, the effect of Zn is difficult to obtain.
Conversely, if it exceeds 30 wt%, the sacrificial corrosion protection ability due to Zn will be saturated. An appropriate amount of Zn to be added is 1 to 30% by weight. Further, Sn, misch metal, Sb, etc. may be added as necessary.

The method for producing the Al-based plated steel sheet is not particularly limited, but the hot-dip plating method is preferred because it is easy to obtain a thicker coating. As the hot-dip plating process, there are a sendzimer method and a flux method. In the case of Al-based plating, plating having an excellent appearance is easily obtained by the sendzimer method. Ni, Co-based pre-plating may be performed before plating. At this time, the interface between the Al—Si plating layer and the substrate
An alloy layer containing i, Co, etc. is generated. The thickness of this layer is not particularly limited, but is preferably 5 μm or less from the viewpoint of workability.

The amount of Al-based plating applied affects the characteristics and the production cost. Naturally, it is preferable that the amount of adhesion is large for corrosion resistance, and that the amount of adhesion is small for spot welding property and cost. The balance of these amounts is about 15 to 60 g / m ^{2 on} one side, and is preferably within this range. For example, when the corrosion resistance of home appliances and the like is not required much, the amount of adhesion is preferably small, and it is desirable that the amount is large for an automotive fuel tank application in which corrosion resistance is important.

The composition of the plating base plate to be used is not particularly limited. However, as a fuel tank material that requires high workability, it is desirable to use IF steel with excellent workability, and furthermore, it is necessary to use B in order to secure the welding airtightness after welding and secondary workability. A steel sheet added with ppm is desirable. For home appliances, both IF steel and Al-k steel are possible. In addition, a normal steel plate manufacturing method is used. The steel component is adjusted and melted by, for example, a converter-vacuum degassing process, and the steel slab is manufactured by a continuous casting method or the like and hot rolled. The present invention specifies the post-treatment, but in addition to the post-treatment film, the post-treatment includes, as post-treatments, a zero spangle process which is a process for homogenizing the appearance after hot-dip plating, an annealing process which is a process for modifying the plating, and a surface condition. There may be temper rolling for adjusting the material, but the present invention is not particularly limited thereto, and can be applied.

Next, the present invention will be described in more detail by way of examples.

EXAMPLES (Example 1) Steels having the components shown in Table 1 were melted by ordinary converter-vacuum degassing to obtain steel slabs, and then hot-rolled, cold-rolled, and continuously under ordinary conditions. An annealing step was performed to obtain an annealed steel sheet (sheet thickness 0.8 mm). After a portion of this steel plate was subjected to Ni plating at 1 g / m ² in a Watt bath, Sn-Zn (-Mg) plating was performed by a flux method. The flux was used by applying a ZnCl ₂ aqueous solution on a roll, and the composition of Zn was changed from 0 to 55%. The composition of Mg is 0 to
Changed to 10%. After plating, the amount of plating was adjusted by gas wiping. This steel sheet was subjected to several types of post-treatment. Table 2 shows the type and composition of the post-treatment. In addition, all the post-treatment films were the same on both surfaces. The properties of the steel sheet thus manufactured were evaluated. The evaluation method at this time was based on the method described below. Table 3 shows the manufacturing conditions and performance evaluation results.
The amount of plating and the amount of post-treatment film are indicated on one side, and the value of post-treatment is expressed in terms of SiO ₂ .

[0023]

[Table 1]

[0024]

[Table 2]

<Evaluation method> (1) Evaluation of lubricity The friction coefficient and cup molding were evaluated. [Friction coefficient value] According to Bowden method, load 500g, 10mm
Measure friction coefficient when φ steel ball slides ◎: friction coefficient value 0.05 or less ○: friction coefficient value 0.05-0.10 △: friction coefficient value 0.10-0.20 ×: friction Coefficient of more than 0.20 [Cup molding] A cup having a drawing ratio of 2.1 is molded, and qualitative evaluation of galling scratches generated on the vertical wall portion ○: no galling Δ: slight galling X: clear galling

(2) Evaluation of Weldability Spot welding was performed under the following welding conditions, and the number of continuous hits until the nugget system fell below 4 at was evaluated. [Welding conditions] Welding current: 10 KA Pressure: 240 Kg Welding time: 12 cycles (60 Hz) Electrode: dome-shaped electrode, tip diameter 6 mm [Evaluation criteria] ：: Over 700 continuous hit points ○: 500 to 700 continuous hit points △: Continuous hit points 300 to 500 points ×: Less than continuous hit points 300 points

(3) Evaluation of Solderability Solder spreadability was evaluated. The solder used was Sn-Ag, and the flux used was a ZnCl ₂ aqueous solution. A certain amount of solder was immersed in a flux, taken out, placed on a test piece, gently placed on heated Pb, and heated. After a certain period of time, the test piece was pulled up and the spread area of the solder was measured by an image analyzer. [Measurement conditions] solder amount: 500 mg Temperature: 300 ° C. Retention time: 45 seconds [Evaluation Criteria] ◎: spread area 300 mm ² than ○: spread area 200 to 300 mm ² △: spread area 100 to 200 mm ² ×: spread area 100 mm ² Less than

(4) Corrosion Resistance Evaluation Corrosion resistance was evaluated by both HCT with a mild corrosive environment and strict CCT test in consideration of use in home appliances and fuel tanks. 1) HCT An HCT test was performed on a test piece having a size of 70 × 150 mm. [Evaluation conditions] Observation of rust occurrence after 49 hours at 49 ° C., 95% RH, 72 hours [Evaluation criteria] ○: No occurrence of red rust, whitening, less than 1% of white rusting △: No occurrence of red rust, whitening, white rusting 1 to 10% ×: Whitening, white rust generation exceeding 10%, or red rust generation

2) A flat-bottomed cylindrical drawing sample having a diameter of 30 mm and a depth of 20 mm was evaluated by a CCT hydraulic molding tester according to JASO (Automobile Standards Association) M610-92 automobile part appearance corrosion test method. [Evaluation conditions] Test period: 140 cycles (46 days) [Evaluation criteria] ：: Red rust occurrence less than 0.1% ○: Red rust occurrence 0.1 to 1% or white rust occurrence △: Red rust occurrence 1 to more than 5% Or white rust conspicuous ×: generation of red rust is more than 5% or white rust is remarkable

(5) Coatability A test piece having a size of 70 × 150 mm was spray-coated. The coating material used was Akko TK Black, a film thickness of 20 μm and a baking time of 140 ° C. × 20 minutes. Next, a cross cut was made in the sample, and 1% in 5% NaCl at 55 ° C.
After dipping for 0 days, taping was performed, and the secondary adhesion of the paint was evaluated based on the peel width of the paint. [Evaluation criteria] ○: Peeling width 5 mm or less △: Peeling width more than 5 to 7 mm ×: Peeling width more than 7 mm

[0031]

[Table 3]

When the amount of the post-treated film is too small as in Comparative Example 1, the lubricity, weldability and paint adhesion are poor.
On the other hand, even when the amount of the post-treatment coating is too large as in Comparative Example 2, the weldability is slightly inferior, and the solderability is also inferior. Further, in the case of pure Sn plating containing no Zn as in Example 1 of the present invention, red rust is easily generated in a severe test such as CCT, and even if the amount of Zn is too large as in Example 8 of the present invention, this time, White rust due to Zn is likely to occur. On the other hand, when the adhesion amount of the plating is large as in Example 12 of the present invention, and when the adhesion amount of the post-treatment film is large as in Example 19 of the present invention, the weldability tends to deteriorate.

High corrosion resistance is also obtained with the Mg-containing plating layers of Examples 20 to 22 of the present invention, and it can be seen that, in Examples 23 and 24 of the present invention, plating containing a mixture of Zn and Mg also has high corrosion resistance. When A containing no metal salt is used as the post-treatment film (Example 13 of the present invention), and when the amount of adhesion of the post-treatment film is small (Example 16 of the present invention), the coating adhesion is slightly deteriorated. When these conditions are proper, the lubricating properties, weldability, solderability, paint adhesion, and corrosion resistance are all excellent. As can be seen from a comparison with Comparative Example 3, the corrosion resistance itself tends to be slightly inferior to that of the chromate treatment, but the Pb which has been conventionally used
The same level as that of -Sn plating, and there is no practical problem. Comparative Examples 3 and 4 have insufficient lubricating properties and have Cr, Pb
Environmentally hazardous substances.

Example 2 The same Sn-Zn plated steel sheet as in Example 1 was used, and only the post-treatment film was changed. Table 4 shows the types of post-processing. A to D post-treatment liquids have a dry solid content of 10
% (Dry at 110 ° C. for 2 hours), and the pH was appropriately adjusted with acetic acid and ammonia. In addition, all the post-treatment films were the same on both surfaces. The properties of the steel sheet thus manufactured were evaluated. The evaluation method at this time is the same as the method of the first embodiment. Table 5 shows manufacturing conditions and performance evaluation results. The amount of plating and the amount of post-treatment film are indicated on one side, and the value of post-treatment is expressed in terms of SiO ₂ .

[0035]

[Table 4]

[0036]

[Table 5]

In Example 2, the solderability generally decreases and the corrosion resistance tends to improve as compared with Example 1. When the adhesion amount of the post-treatment film is too small as in Comparative Example 1, lubricity, weldability and paint adhesion are poor. On the other hand, even when the amount of the post-treatment coating is too large as in Comparative Example 2, the weldability is poor and the solderability is also poor. Further, when the amount of plating is small as in Example 9 of the present invention, the solderability tends to be slightly inferior. On the contrary, in Examples 11 and 12 of the present invention having a large amount of plating, the weldability is slightly reduced. High corrosion resistance is also obtained with the Mg-containing plating layers of Examples 20 to 22 of the present invention.
It can be seen that the mixed-containing plating of Zn and Mg also has high corrosion resistance.

On the other hand, when the adhering amount of the post-treatment film is small as in Example 16 of the present invention, or when the composition of the film is not proper as in Example 13 of the present invention, the paintability is somewhat poor.
When the film is too thick as in the case of No. 19 to 19, the solderability is deteriorated. When these conditions are proper, the lubricating properties, weldability, solderability, paint adhesion, and corrosion resistance are all excellent. As can be seen from the comparison with Comparative Example 3, the solderability tends to be slightly inferior to that of the chromate treatment, but it is expected that there is no practical problem if the selection of the flux or the like is appropriately selected. Comparative Examples 3 and 4 are insufficient in lubricity and use Cr and Pb, which are environmental load substances.

(Example 3) A cold rolled steel sheet having the steel composition shown in Table 1 of Example 1 was used as a material, and the molten Sn-
8% Zn plating was performed. For the hot-dip Sn-Zn plating, a line of a non-oxidizing furnace-reduction furnace type was used, and annealing was also performed in this hot-dip plating line. Annealing temperature is 800 ~ 850 ℃
And After plating, the coating weight was adjusted to 40 g / m ² on one side by gas wiping. The plating temperature at this time is 28
0 ° C. Further, using the solution B in Table 2, post-treatment was performed on one side at 60 mg / m ^{2 in} terms of silica. When the characteristics of the steel sheet manufactured in this manner were evaluated by the method of Example 1,
The lubricity, weldability, solderability, HCT, CCT, corrosion resistance, and paint adhesion were all evaluated as ○, indicating good characteristics.

(Example 4) Steel having the components shown in Table 1 of Example 1 was melted by ordinary converter-vacuum degassing to form a steel slab, and then hot-rolled and cold-rolled under ordinary conditions. Perform the rolling process,
A cold-rolled steel sheet (sheet thickness 0.8 mm) was obtained. NOF
-Al-Si-Mg in RF type hot dipping line
(-Zn) plating was performed. After plating, the amount of plating was adjusted by gas wiping. Al, S for plating bath
In addition to i, Mg, and Zn, about 1 to 2% of Fe eluted from a steel plate or the like was contained as an impurity. The plated steel sheets produced in this manner were temper rolled with rolls having various roughnesses to adjust the surface roughness. This steel sheet was subjected to several types of post-treatment. Table 6 shows the type and composition of the post-treatment. In addition, all the post-treatment films were the same on both surfaces. The properties of the steel sheet thus manufactured were evaluated. The evaluation method at this time was based on the method described below. Table 7 shows the manufacturing conditions and performance evaluation results. The amount of plating and the amount of post-treatment film are indicated on one side, and the value of post-treatment is expressed in terms of SiO ₂ .

[0041]

[Table 6]

[0042]

[Table 7]

<Evaluation Method> (1) Evaluation of Lubricity The friction coefficient was evaluated by cup molding. [Friction coefficient] Load: 500 g, 10 mm by Bowden method
Measure friction coefficient when φ steel ball slides ◎: friction coefficient value 0.05 or less ○: friction coefficient value 0.05-0.10 △: friction coefficient value 0.10-0.20 ×: friction Coefficient of more than 0.20 [Cup molding] A cup having a drawing ratio of 2.1 is molded, and qualitative evaluation of galling scratches generated on the vertical wall portion ○: no galling Δ: slight galling X: clear galling

(2) Evaluation of Weldability Spot welding was carried out under the following welding conditions, and the number of continuous hits until the nugget system fell below 4 at was evaluated. [Welding conditions] Welding current: 10 KA Pressure: 240 Kg Welding time: 12 cycles (60 Hz) Electrode: dome-shaped electrode, tip diameter 6 mm [Evaluation criteria] 連 続: Continuous hitting point exceeds 700 points ○: Continuous hitting point 500 to 700 points △: Continuous hit points 300 to 500 points ×: Less than continuous hit points 300 points

(3) Corrosion resistance evaluation Corrosion resistance was evaluated by both HCT with a mild corrosive environment and strict CCT test in consideration of home electric appliances and fuel tank applications. 1) HC for test specimen of HCT size 70 × 150 mm
A T test was performed. [Evaluation conditions] Observation of rust occurrence after 49 hours at 49 ° C., 95% RH, 72 hours [Evaluation criteria] ○: No occurrence of red rust, whitening, less than 1% of white rusting △: No occurrence of red rust, whitening, white rusting 1 to 10% ×: Whitening, white rust generation exceeding 10%, or red rust generation

2) A flat-bottomed cylindrical sample having a diameter of 30 mm and a depth of 20 mm was processed by a CCT hydraulic molding tester and evaluated by the JASO (Automobile Standards Association) M610-92 automobile part appearance corrosion test method. [Evaluation conditions] Test period: 140 cycles (46 days) [Evaluation criteria] ：: Red rust occurrence less than 0.1% ○: Red rust occurrence 0.1 to 1% or white rust occurrence △: Red rust occurrence 1 to more than 5% Or white rust conspicuous ×: generation of red rust is more than 5% or white rust is remarkable

(4) Paintability A test piece having a size of 70 × 150 mm was spray-coated. The coating material used was Akko TK Black, a film thickness of 20 μm and a baking time of 140 ° C. × 20 minutes. Next, a cross cut was made in the sample, and 1% in 5% NaCl at 55 ° C.
After dipping for 0 days, taping was performed, and the secondary adhesion of the paint was evaluated based on the peel width of the paint. [Evaluation criteria] ○: Peeling width 5 mm or less △: Peeling width more than 5 to 7 mm ×: Peeling width more than 7 mm

When the amount of the post-treated film adhered is too small as in Comparative Example 1, the lubricity, weldability and paint adhesion are poor.
On the other hand, as in Comparative Example 2, even when the amount of the post-treatment coating film is too large, the weldability is slightly inferior. In the case of Al plating with a low Si content as in Example 1 of the present invention, an alloy layer easily grows, and when subjected to a severe test after processing such as CCT, red rust is easily generated. On the other hand, the present invention examples 4, 6 to 9, 17 to
As in 20, the corrosion resistance is improved by containing Mg or Zn in the plating layer. When A containing no metal salt was used as the post-treatment film (Example 10 of the present invention), and when the amount of the post-treatment film attached was small (Example 13 of the present invention), the coating adhesion was slightly deteriorated. When these conditions are proper, the lubricating properties, weldability, solderability, paint adhesion, and corrosion resistance are all excellent. Comparative Examples 3 and 4 have insufficient lubricity, and
The environmentally hazardous substance b is used.

(Embodiment 5) The same Al-Si-
Mg (-Zn) plated steel sheet was used, and only the post-treatment film was changed. Table 8 shows the type and composition of the post-treatment. The post-treatment liquids of A to D had a dry solid content of 10% (dry at 110 ° C. for 2 hours), and the pH was appropriately adjusted with acetic acid and ammonia. In addition,
All post-treatment films were treated the same on both sides. The properties of the steel sheet thus manufactured were evaluated. The evaluation method at this time is the same as the method of the fourth embodiment. However, the surface roughness was measured before applying the post-treatment film. Table 9 shows the manufacturing conditions and performance evaluation results.
Shown in The amount of plating and the amount of post-treatment film are indicated on one side, and the value of post-treatment is expressed in terms of SiO ₂ .

[0050]

[Table 8]

[0051]

[Table 9]

When the amount of the post-treated film adhered is too small as in Comparative Example 1, the lubricity, weldability and paint adhesion are poor.
On the other hand, also in the case where the post-treatment film adhesion amount is too large as in Comparative Example 2, the weldability is poor. In addition, Example 11 of the present invention having a large amount of plating adhesion slightly deteriorates weldability. On the other hand, when the adhesion amount of the post-treatment film was small as in Example 13 of the present invention,
When the composition of the film is not proper as in the above, the coatability is slightly inferior. When the film is too thick as in Examples 15 and 16 of the present invention, the weldability deteriorates. If the various conditions are appropriate, the lubricity, weldability, paint adhesion, and corrosion resistance are all excellent. Comparative Examples 3 and 4 are insufficient in lubricity and use Cr and Pb, which are environmental load substances.

[0053]

The present invention is to provide Sn-based and Al-based surface-treated steel sheets which are excellent in lubricity, weldability, solderability and corrosion resistance without using any environmentally harmful substances such as Pb and Cr. The industrial contribution is great. Patent applicant Attorney of Nippon Steel Corporation Patent attorney
Jin Shiina

Continuation of the front page (72) Inventor Masahiro Fuda 1-1-1, Hibata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture F-term in the Nippon Steel Corporation Yawata Works (reference) 4K026 AA09 AA10 AA13 AA22 BA01 BA03 BA08 BB04 BB06 BB08 BB09 CA16 CA18 CA26 CA32 CA33 CA39 CA41 DA15 4K027 AA02 AA05 AA22 AB02 AB05 AB09 AB46 AB48 AC82 AE03 AE21

Claims (4)

[Claims] 1. The surface of Sn, Sn alloy, Al, Al alloy plating does not contain Cr and is 10 to 100 in terms of SiO _2.
An Sn-based or Al-based plated steel sheet provided with a post-treated film containing 0 mg / m ² of Si, P and C and a lubricant of 1 wt% or more of the film amount. 2. The post-treatment film contains Ni, Zn, Al, M
1 or 2 of g, Ti, Co, Mn, Sn, Fe, Zr
Species or more salts, Sn system according to claim 1, characterized in that it contains a ratio of 0.01 to 0.5 relative to the amount of SiO ₂ as the sum of terms of the metal weight, Al-based plated steel sheet. 3. The composition of a plating layer is as follows: Zn: 3 to 50%;
The Sn-based plated steel sheet according to claim 1, wherein one or more of Mg: 0.1 to 10% is contained, and the balance is Sn and inevitable impurities. 4. The composition of a plating layer is as follows: Si: 3 to 15%;
1 or 2 of Mg: 0.1 to 15% and Zn: 1 to 30%
The Al-based plated steel sheet according to claim 1, wherein the Al-based steel sheet contains at least seeds and the balance is Al and inevitable impurities.