WO1984000039A1

WO1984000039A1 - Molten zinc-plated alloy and plated steel strips and steel materials coated with said alloy

Info

Publication number: WO1984000039A1
Application number: PCT/JP1983/000190
Authority: WO
Inventors: Takehiro Isobe; Tatsuji Hashimoto
Original assignee: Nippon Soda Co
Priority date: 1982-06-15
Filing date: 1982-06-14
Publication date: 1983-01-05
Also published as: JPS58221250A; JPS6033892B2; AU1607483A

Abstract

An alloy for hot dipping comprising 3.5 to 5.0 wt. % of Al, 0.05 to 0.5 wt. % of Si, 0.01 to 0.5 wt. % of Mg, and the balance of Zn. A coating formed by using this alloy shows excellent corrosion resistance and adhesive properties and depresses elution of iron into the hot dipping bath, thus making the bath composition stable and, therefore, improving hot dipping workability markedly. Molten zinc-plated steel strips and materials having the alloy coating of the present invention have excellent adhesive properties of the coating so that they show excellent workability.

Description

Specification

Title of invention

Hot-dip zinc alloy and coated with the alloy

Mesh nets and ropes Detailed description of the invention

Field of technology

The present invention relates to a molten zinc plating alloy, and more particularly to a Zn-A-Si molten plating alloy, a plating clad plate and a plating pot material coated with the alloy. Technology background

In recent years, the use of zinc plating products as a material for iron pots has been expanding steadily, and at the same time, a plating alloy having higher corrosion resistance and adhesion has been demanded. As a method of improving the shochu resistance of zinc plating products, a method of generally increasing the amount of zinc adhered, and adding elements such as Al, Pb, Sn, Ti, and Si, which are said to be effective in improving corrosion resistance A method has been proposed. However, the fusion plating method has a problem in the stability of the alloy composition during plating and has a drawback in that the adhesion and corrosion resistance vary. In order to improve these drawbacks, a Zn-A to Si-based molten metal alloy consisting of A1: 55 wt% and Si: 1.5 t% residual Zn has been adopted. However, these alloys have disadvantages that the plating bath temperature is high, the working atmosphere is poor, and sacrificial corrosion protection is not sufficiently satisfied. As a method for lowering the melting temperature, an alloy in which the A1 content has been reduced to 10 wt% or less has been proposed. For example, JP-50- one hundred and four thousand seven hundred thirty-one issue in JP A1: 5 to 20 wt%, Si rather 5 _W t%, the alloy composition of the residual Zn is also in JP-A-54- 23033 A1: 2 ~ 20wt %, Si: 0.001 to 0.5 wt%, Sn: 0.01 to 0.1 wt%, and the alloy composition of residual Zn. However, in the former case, the corrosion resistance of the obtained coating film is insufficient, and in the latter case, the corrosion resistance is extremely high. Although a peeled coating film is obtained, it is separated by processing such as bending, that is, it has a defect of poor adhesion and workability.

An object of the present invention is to provide a hot-dip zinc alloy having excellent corrosion resistance, adhesion, and workability, and a metal coating excellent in li resistance and workability formed by coating the alloy. The purpose of 别 is to provide woodpecker boards and netting.

The present inventors have conducted intensive studies to achieve the above object, and found that a small amount of Mg was added to the alloy composition consisting of A1: 3.5 to 5.0 wt%, Si: 0.05 to 0.5 wt%, and the balance of Zn. As a result, a paint film having excellent sensitivity, adhesion, and processability can be obtained, and more surprisingly, there is almost no elution of iron into the paint bath, and the paint composition is stable and workability is improved. Was found to be significantly improved, and the present invention was completed. Disclosure of the invention

In this study, we found that: A1: 3.5-5.0 wt%, Si: 0.05-0.5 wt%, Mg: 0.01-0.5 wt%, residual Zn and unavoidable impurities. And a mesh net and a net material coated with the alloy.

In the molten metal alloy of the present invention, a metal coating film obtained by adding about 3.5 wt% of A1! The ¾ property reaches saturation, and an A1 rich phase (phase) is crystallized as a primary crystal by the addition of about 5.0%. The upper limit of the amount of Si added is 0.5 wt% with the eutectic composition of A1Z Si as the limit, and the lower limit is 0.05 «t% from the solid solubility at the plating bath temperature. The addition of Mg is effective in suppressing the intergranular corrosion of the resulting plating film, and the effect is further increased by coexistence with Si. The amount of ilg ^ varies depending on the content of unavoidable impurities such as Pb, Cd, Sn, etc. in the raw materials used, but at least 0.01> ^% is required, and 0.5wt% is sufficient. Since the Fe content in the metal powder greatly affects the heat resistance, it is preferable to limit Fe: 0.02 wt% or less as an impurity in the alloy. The production method of the molten metal alloy of the present invention is not particularly limited, and it may be produced by melting and mixing each raw metal in the above-described ratio in a crucible. You may melt-mix directly.

The plating net plate and the net material formed by coating the molten plating alloy of the present invention have a plating film excellent in corrosion resistance and adhesion regardless of the plating method. The plating film has an extremely high corrosion resistance of 0.15 π 以下 hr or less in a salt spray test and 0.05 to 0.08 g / nf · hr under optimum conditions, and taping after 2T bending. It shows excellent adhesion in the test. That is, the plated steel sheet and the steel material also have excellent workability. The reason why the paint film has excellent corrosion resistance and adhesiveness must be determined by future studies, such as the resolution of the S boundary by electron microscopy. This is presumed to be due to the large effect and the extremely low elution of Fe into metal shells using the alloy. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a corrosion amount curve of a plating film obtained by using the molten plating alloy of the present invention by a salt spray test together with a comparative example.

The vertical axis is the amount of corrosion (g / m'hr)

The horizontal axis represents the A1 addition rate (wt%).

A: Si 0.13%, Mg 0.01%

B Si 0.13% Mg 0.05%

C Si 0.25% Mg 0.03%

D Si 0.50% Mg 0.03%

E Si-added Mg-free system (Comparative example)

F Si-free Mg-added system (Comparative example)

G Si-free and Mg-free system (Comparative Example) Fig. 2 shows the relationship between the amount of decay and the Fe content and the O content of Mekkoro by the salt spray test on the paint film together with the comparative example.

O PI The vertical axis is the corrosion weight loss (gZnf · hr)

撗轴 represents the Fe content (wt%) in the plating bath.

A: A1 4.5% Si 0.13%

B: A1.5% Si-free system (Comparative example)

Fig. 3 shows the outflow curves of Fe in various plating bath compositions.

In the vertical transportation, the amount of Fe eluted (g)

癀铀 represents the immersion time (hr) of Fe.

A: A 1.5% Si 0.13% «g 0.01%

B Al 4.5% Si 0.13% Mg additive free system (Comparative example)

C Al .5% Si-free Mg 0.01% system (Comparative example)

D Al .5% Si free 《g free system (Comparative example)

E Al 0.16% Pb 0.15% (Comparative Example) Fig. 4 Immersion time of Fe in plating bath of various compositions and salt of plating film

3 shows a spoilage curve obtained by a water-pupil fog test.

Longitudinal corrosion loss (g / nf · hr)

The symbol indicates the immersion time (hr) of Fe.

A: A1 4.5% Si 0.13¾ Mg 0.01%

B A1 4.5% Si 0.13% Mg additive free system (comparative example)

C A1 4.5% Si-free Mg 0.01% (Comparative example)

D A1 4.5% Si-free Mg-free system (Comparative example)

E A1 0.16% Pb 0.15% system (Comparative Example) Fig. 5 shows the immersion time of Fe in plating baths of various compositions and the A1 composition change curve in plating baths.

The vertical axis is the value of A1 fraction in Mekuki Rakuchu (wt%).

撗钴 represents the immersion time (hr) of Fe.

A: A1 4.5% Si 0.13% Mg 0.01%

B: A1 4.5% Si 0.13% Mg additive free system (comparative example)

C: A1.5% Si-free Mg 0.01% (Comparative example)

D: A 1.5% Si-free Mg-free system (Comparative example)

O PL. E: Al 0.16% Pb 0.15% system (Comparative Example) Fig. 6 Immersion time of Fe in plating bath of various compositions and Fe in plating bath

3 shows a composition change curve.

In the vertical transport, the Fe content value in Mekkoki (wt%)

The horizontal axis indicates the immersion time (hr) of Fe.

A: A1 4.5% Si 0.13% Mg 0.01%

B: A1 4.5% Si 0.13% Mg additive free system (comparative example)

C: A1 4.5% Si-free Mg 0.01% system (Comparative example)

D: A 1.5% Si-free Mg-free system (Comparative example)

E: A1 0.16% Pb 0.15% (Comparative Example) Best mode for carrying out the invention

BEST MODES FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described below with reference to Examples and Comparative Examples in which a substrate is a plated object. However, the scope of the present invention is not limited to only the molten plating alloy, the plating method, and the plated steel sheet shown in the following examples, but may be a plating method using a known plating method. It also extends to sidings and stakes.

Examples and comparative examples

A1 Alloys of various compositions consisting of 3.5 to 7.6 wt%, Si 0 to 0.25 wt%, Mg 0 to 0.5 wt%, residual Zn and unavoidable impurities were melted in a graphite crucible set in a small electric furnace. A cold-rolled slab with a thickness of 0.3 mm was washed with a 6 wt% aqueous solution of caustic soda, washed with water, pickled with 8 wt% hydrochloric acid, and washed again with water. Next, a flux treatment was performed in a mixed solution of a flux containing ZnCl ₂ as a main component, and dried at a temperature of 200'c using an electric furnace. Immerse the treated net in the molten alloy at a temperature of 480 excluding the dross, remove the dross on the surface immediately before lifting, pull it up, and let it cool in the air to produce a plated steel plate did. The immersion time was 10 seconds.

As the ingots used, rectified zinc (Zn> 99.99), aluminum (JI SH 2102 aluminum ingot two or more equivalents), silicon (Si> 99.9%), The mother alloy was melted using Gnesium (JIS-H 2150 magnesium ingot 1 or more).

The following tests were carried out on the prepared shingle boards.

(1) Adhesion amount measurement Antimony chloride method UIS-H0401)

(2) Corrosion weight loss after 72 hours in saltwater fog test (according to JIS-Z 2371)

(3) Steam test After leaving for 3 days in saturated steam of 98, 2T

After bending, observe the appearance and observe the appearance using a tabing test.

Table 1 shows the composition of the fish and the test results.

(Hereinafter the margin)

O PI Table 1

Mekaku composition («t%) adhesion rot li steam test

Quantity

g Bending tape 1 • N 7o A1 ng Sn Zn irf πί hr

3.5 0.13 0.01 246 0.14 4 ◎

3.5 0.13 0.05 240 0.13 4 ◎

3.7 0.25 0.03 146 0.08 4 ◎

3. 0.50 0.03 141 0.08 5 ◎

4.5 0.13 0.01 292 0.07 4 ◎

4.5 0.13 0.05 272 0.06 4 ◎

4.5 0.13 0.10 220 0.06 ◎

4.5 0.13 0.25 221 0.06 4 ◎

4.5 0.13 0.50 268 0.06 4 Allocation 10 4.5 0.20 0.25 198 0.05 4

11 4.5 0.20 0.50 202 0.05 4

12 4.5 0.25 0.03 188 0.05 ◎ Example 13 4.5 0.50 0.03 227 0.07 4 ◎

14 4.5 0.50 0.25 220 0.06 4 ◎

15 4.9 0.13 0.10 210 0.08 4 ◎

16 4.9 0.13 0.25 210 0.06 4 <§>

4.9 0.13 0.50 189 0.07 ◎

18 4.9 0.20 0.25 190 0.06 4 ◎

19 4.9 0.20 0.50 193 0.07 4

20 4.9 0.25 0.0 229 0.07 4 ◎

21 4.9 0.50 0.03 160 0.08 4 ◎

22 4.9 0.05 0.25 200 0.07 4 ◎

f O PI (Continued)

Body composition (wt%) Adhesion Corrosion Steam test Weight loss

g bending

No Al Si ng Sn Zn nf πί hr

0.2 256 0.68 4 ◎

2 3.5 224 0.28 X

3.5 0.13 231 0.18 m

3.5 0.01 235 0.14 m

3.5 0.05 218 0.14 ◎ Ratio 4.5 208 0.24 mm

4.5 0.01 216 0.12 m

4.5 0.05 260 0.12 ◎

4.5 0.13 234 0.09

10 4.5 0.13 0.1 261 0.09 X

11 4.5 0.13 0.01 0.220 0.09 X Example 12 4.5 0.13 0.05 0.1 304 0.09 X

13 5.5 215 0.27 2 m

14 5.5 0.13 211 0.12 4 m

15 5.5 0.01 246 0.13 m

16 5.5 0.05- 211 0.13 ◎

17 5.5 0.13 0.01 212 0.11 4 m

18 5.5 0.13 0.05 232 0.11 △

19 .6 0.23 250 0.23

In Table 1, the appearance after 2T bending is represented by the following five levels,

1: Cracks are observed on the entire surface with the naked eye.

2: Cracks are partially observed with the naked eye.

3: Some cracks are observed with double loupe.

4: Something like a crack is observed with a 2x loupe.

5: 2 times. No cracks are observed on the loupe.

The appearance after the taping test is indicated as follows.

O PI ◎: No separation was observed.

MM: Partial peeling is observed.

X: Peeling is observed on the entire surface.

Test example 1

Fe was added to a molten alloy having the same composition as in Comparative Examples 6 and 9, and a mesh plate treated in the same manner as in the example was immersed and pulled up in the same manner as in the example, to thereby produce a steel sheet. A salt spray test was performed on the prepared fishing net plate in the same manner as in the example, and the corrosion loss and the Fe content in the fishing net were measured.

Figure 2 shows the relationship between the Fe content and the amount of corrosion in the metal shell.

Test example 2

A steel sheet treated in the same manner as in the example was immersed in a molten alloy having a typical composition of the example and the comparative example. Was measured and Fe and A1 in the plating bath were analyzed. The results obtained are shown in FIGS. 3 to 6.

Industrial applicability

It is apparent from Table 1 and FIG. 1 that the addition of Si and Mg in the molten metal alloy of the present invention significantly improves the corrosion resistance and adhesion of the obtained metal coating. . As is clear from FIGS. 3, 5, and 6, the addition of Si has an effect of suppressing the elution of Fe into the plating bath and stabilizing the plating bath composition. As shown in Fig. 2, the Fe content in the metal has a great effect on the corrosion resistance. Therefore, Fe as an impurity in the alloy is preferably kept at less than 0.02 wt%. In addition, by setting A1 to less than 5.0 wt%, the work can be performed at a normal mech temperature.

The plating plate and the net material of the present invention, which are formed by coating the plated metal alloy, have excellent corrosion resistance and adhesion as described above, and also have extremely good workability thereafter. .

The present invention provides an OMPI with excellent workability and excellent corrosion resistance and adhesion. The present invention provides a Zn-iU-Si based molten plating alloy from which a coating can be obtained, and a plating mesh plate and a net material formed by coating the alloy, and their industrial significance is extremely large.

(Hereinafter the margin)

Claims

Range of desperation

1 A1: 3.5-5.0wt%, Si: 0.05-0.5wt%, Mg: 0.01-0.5 «t%, residual Zn and unavoidable impurities.

2 A1: 3.5 ~ 5.0wt%, Si: 0.05-0.5wt%, Mg: 0.01-0.5wt%, coated with a molten metal alloy consisting of residual Zn and unavoidable impurities.

3 A1: 3.5-5 * 0 ", Si: 0.05-0.5wt%, Mg: 0.01-0.5wt%, and a molten metal alloy consisting of residual Zn and unavoidable impurities. Tsuki Steel

OMPI