JPH06228727A - Plated steel wire excellent in corrosion resistance and its production - Google Patents

Abstract

PURPOSE:To produce a highly corrosion resistant plated steel wire where secondary corrosion resistance of material as well as primary corrosion resistance of plating is improved and both are correlatively improved and which is used under a corrosive atmosphere, such as rivers and sea coast. CONSTITUTION:A wire, having a composition consisting of <=0.17% C, <=0.20% Si, <=0.70% Mn, 2.0-4.0% Ni, and the balance Fe with inevitable impurities, a highly corrosion resistant plated steel wire, having a hot-dip galvanizing layer consisting of Zn, as first-stage plating layer, on the surface of the above wire and further having, as second-stage plating layer, a hot-dip zinc-aluminum alloy coating layer containing >=3% Al on the layer, and the steel wire prepared by applying first-stage hot-dip galvanizing to the wire by the use of simple substances of zinc chloride and ammonium chloride or a mixture thereof as flux and then immediately applying hot-dip zinc-aluminum alloy coating containing >=3% Al, are produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-aluminum alloy plated steel wire excellent in corrosion resistance, workability and wear resistance, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years, society's demands for protection of the natural environment and protection from natural destruction have been increasing year by year, and it has been desired that the protection of coasts and rivers be carried out reliably and quickly. Therefore, the construction method for these works is changing from the concrete covering method to the cage method using wire mesh.

[0003] The conventional requirements for the squirrel cage were mainly for temporary revetments, but in recent years, the demand for full-scale revetments has been increasing. For this reason, the development of thick-plated steel wires and alloy-plated steel wires having improved durability and higher durability has been promoted (Japanese Patent Publication No. 1-54428). However, in the market, a further increase in service life is desired.

According to the research conducted by the inventors, particularly in the plated steel wire used for revetment, the plated layer is flawed due to mechanical force such as turbulent flow due to flooding of the river or due to rising water in the river. , It was found that rust was generated from the flawed part, shortening the life of the plated steel wire.

[0005]

The present invention does not rely solely on the primary corrosion resistance of plating as in the prior art, but
It also aims to improve secondary corrosion resistance as a material and to improve the corrosion resistance in combination with each other, and to provide a highly corrosion resistant plated steel wire to be used in corrosive atmospheres such as rivers and coasts, and a manufacturing method thereof. The purpose is to

[0006]

In order to achieve the above object, the present invention has the following structures. That is, (1)
As weight%, C: 0.17% or less, Si:
0.20% or less, Mn: 0.70% or less, Ni:
It has an element wire composed of 2.0 to 4.0%, the balance being Fe and unavoidable impurities, and a hot-dip galvanized layer made of Zn as a first-stage plated layer on the surface thereof, and further 3 Al as a second-stage plated layer % Or more, and a coated steel wire having a hot-dip zinc-aluminum alloy plating layer containing at least 100% by weight, and (2) wt% as C: 0.17% or less, Si: 0.
20% or less, Mn: 0.70% or less, Ni: 2.
A single wire or a mixture of zinc chloride and ammonium chloride is used as a flux for a wire consisting of 0 to 4.0%, the balance being Fe and inevitable impurities, and Z is used as a first plating layer.
hot-dip galvanized steel containing 3% or more of Al as the second-stage plating immediately after the first-stage plating.
It is a method for producing a plated steel wire having excellent corrosion resistance, which is characterized by performing aluminum alloy plating.

The components of the strands according to the present invention will be described below. C is 0.17% or less. That is, C
Is an element having high hardenability, and if it exceeds 0.17%, toughness is deteriorated. Si is 0.20% or less. That is, Si is contained in order to maintain appropriate oxidation resistance. If it is too high, the formation of the protective oxide film is hindered, and at the same time, the toughness is lowered.

Mn is 0.70% or less. That is,
Mn is used as a strengthening element with a small decrease in toughness,
This is because if it exceeds 0.70%, the hardenability becomes excessive and the toughness deteriorates like C. Ni is set to 2.0 to 4.0%. N
Corrosion resistance is improved by adding i in the low S region where the S content is 0.005% or less. Further, Ni is a solid solution in the base iron and improves strength and toughness. If it is less than 2.0%, its effect becomes small, and in consideration of alloy cost, 4.0%.
Below.

Note that P and S are other elements that affect the corrosion resistance. P is an unavoidable element as an impurity, and if it exceeds 0.015%, salt resistance deteriorates, so it is preferable to set it to 0.015% or less. When S is combined with P in an amount of 0.005% or less, salt resistance is significantly improved, so S is preferably 0.005% or less. The above is the description regarding the basic components of the strands according to the present invention.

Next, the surface plating layer will be described. In the plating layer in the present invention, a steel layer is formed with a plating layer containing zinc as a main component as a first-stage plating layer, and a zinc-aluminum alloy plating layer is further formed thereon as a second-stage plating layer. As a specific means for forming the plating layer, a hot dip zinc bath and a hot dip zinc-aluminum alloy bath containing high-concentration aluminum are separately installed, and the steel wire to be plated is treated with the flux exactly the same as the galvanization. -After the drying process, first place in a hot dip zinc bath for galvanizing. Then, it is immersed in a molten zinc-aluminum alloy bath to which aluminum is added to perform zinc-aluminum alloy plating. The appropriate Al content in the zinc-aluminum alloy bath is in the range of 3 to 15%.
If the amount of aluminum is less than 3%, the corrosion resistance targeted by the present invention cannot be obtained, and if it exceeds 15%, the effect is saturated and the economical efficiency is reduced.

[0011]

The structure of the wire according to the present invention is a low alloy steel having excellent corrosion resistance and excellent galvanizability, and the plated layer on the surface is a zinc-aluminum alloy. It can withstand strong bending and has excellent corrosion resistance as a whole.
In particular, it is effective in applications where there is a risk of damage to the plating layer due to scratching, such as applications in a revetment basket.

Since the present invention uses exactly the same flux as the conventional hot-dip galvanizing, no unplated portion is generated and good zinc-aluminum alloy plating can be performed, which is extremely advantageous as a plating treatment. Further, in the method of the present invention, since neither the molten zinc bath nor the molten zinc-aluminum bath uses lead, if zinc ingot and zinc-aluminum alloy ingot are selected, the lead content in each bath is Can be controlled to 0.1 to 0.2% or less, and therefore the lead content in the zinc-aluminum alloy plating layer on the surface of the steel wire after plating can be suppressed to a low level, and zinc having excellent corrosion resistance can be controlled. -Aluminum alloy plated steel wire can be obtained.

[0013]

Embodiments of the method of the present invention will be described in detail below with reference to the drawings. FIG. 1 is an example of a manufacturing process of the zinc-aluminum alloy plated steel wire of the present invention. The steel wire 1 which has been treated with exactly the same flux as in the known hot dip galvanizing process and which has undergone the drying step is first charged in the hot dip zinc bath 3 in the hot dip zinc bath 2 and galvanized. When pulling up the steel wire 1 from the hot-dip galvanizing bath 3, squeezing is performed by a squeezing device 5 such as asbestos or wire as in the conventional hot-dip galvanizing. Galvanized steel wire 1 is then alloy bath 7
It is charged in a molten zinc-aluminum alloy bath 8 containing a high concentration of aluminum therein, and zinc-aluminum alloy plating is performed. The metal used in both the molten zinc bath 3 and the molten zinc-aluminum alloy bath 5 has a lead content of 0.1.
Since the content of .about.0.2% or less is used, the lead content of the plating layer of the steel wire 1 can be suppressed to 0.1 to 0.2% or less.

The steel wire 1 is pulled up vertically from the molten zinc-aluminum bath 8. At this time, an extremely light squeeze is performed by a squeezing device 10 such as asbestos so that oxides and the like on the bath surface do not adhere to the steel wire surface. . Then, it is immediately cooled by the cooling device 11. The main purpose of the cooling performed here is to prevent the zinc-aluminum alloy plated on the surface of the steel wire from sagging, to reduce the surface irregularities as much as possible, and to bring the zinc to a temperature suitable for the surface finishing process in the next roll die device 12. -To lower the aluminum alloy temperature.

The cooled steel wire 1 enters the roll die device 12 as necessary to smooth the surface irregularities of the steel wire.
The surface temperature of the steel wire 1 immediately before entering the roll die device 12 is preferably a temperature within a range in which solidification of the zinc-aluminum alloy starts and the zinc-aluminum alloy has sufficient ductility. In addition, the roll die device 12 has
In order to prevent the zinc-aluminum alloy on the surface of the steel wire from adhering to the roll die, it is preferable to consider the material of the roll, the degree of polishing of the roll surface, the cooling of the roll and the like. 4, 6, 9 in the figure
Is a guide roll.

The steel wire 1 drawn out from the zinc-aluminum alloy bath passes through a guide roll (not shown) and is then wound by a winder. The amount of plating adhered can be freely selected by increasing or decreasing the linear velocity. As described above, the zinc-aluminum alloy-plated steel wire of the present invention has no defects such as non-plating, can control the lead content in the plating layer to a low level, and also has a high adhesion amount, and thus is more excellent in corrosion resistance,
Furthermore, it has a beautiful surface texture and is soft and stretchable with excellent workability and corrosion resistance. Also. It can be easily manufactured.

Next, specific examples of the present invention will be described. Table 1
The components of the test material are shown in. Steel type A is a wire according to the present invention, and steel type B is a conventional wire (JIS) used for comparison.
Standard: SWRM6K).

[0018]

[Table 1]

The diameter of each strand was 5.0 mm.
These strands were plated using the manufacturing apparatus shown in FIG. The first-stage plating was carried out by maintaining the bath temperature at 460 ° C. by a molten zinc bath containing substantially Zn. The second stage plating was performed by keeping the bath temperature at 450 ° C. in a zinc-aluminum alloy bath containing 10.0% Al.

The plated wire thus obtained was subjected to a salt spray test (JIS Z2371) for evaluating corrosion resistance. The results are shown in Table 2 and FIG. Test No. 1
Of the present invention, No. 2 and 3 are comparative examples. As shown in Table 2 and FIG. 2, it is clear that the one according to the present invention has extremely small corrosion weight loss and remarkably excellent corrosion resistance. In addition, mechanical property values are shown in Table 3. From the table,
It is clear that the plated wire according to the present invention has less cracking and peeling during processing than other comparative plated wires and does not adversely affect the plating life.

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

As described above, according to the present invention, it is possible to obtain a plated wire and a plated product which are much more excellent in corrosion resistance than before.

The zinc-aluminum alloy-plated steel wire of the present invention was compared with the corrosion resistance in a salt spray test, and as a result, the corrosion weight loss was about ⅛ of that of the conventional plated steel wire. Is good.

[Brief description of drawings]

FIG. 1 is a process drawing showing a manufacturing process of the present invention.

FIG. 2 is a table showing the relationship between salt spray time and corrosion weight loss in Examples.

[Explanation of symbols]

 1 Steel Wire 2 Molten Zinc Bath 3 Molten Zinc Bath 4, 6, 9 Guide Roll 5, 10 Throttling Device 7 Molten Zinc-Aluminum Alloy Bath 8 Molten Zinc-Aluminum Alloy Bath 11 Cooling Device 12 Roll Die Device

Claims (2)

[Claims] 1. As a weight%, C: 0.17% or less Si: 0.20% or less Mn: 0.70% or less Ni: 2.0 to 4.0% A wire comprising balance Fe and inevitable impurities. , Which has a hot-dip galvanized layer containing Zn as a main component on its surface and a hot-dip zinc-aluminum alloy plated layer containing 3% or more of Al as a second-step plated layer, which has excellent corrosion resistance. Galvanized steel wire. 2. As a weight%, C: 0.17% or less Si: 0.20% or less Mn: 0.70% or less Ni: 2.0 to 4.0% A wire comprising balance Fe and unavoidable impurities , A single or mixture of zinc chloride and ammonium chloride is used as the flux, hot-dip galvanizing containing Zn as the main component is performed as the first plating layer, and 3% or more of Al is used as the second plating immediately after the first plating. A method for producing a plated steel wire having excellent corrosion resistance, which comprises performing hot dip zinc-aluminum alloy plating containing the steel.