WO2018199362A1 - Plated steel wire with zinc alloy plating layer having multilayer structure formed thereon, and method for manufacturing same - Google Patents

Abstract

The present invention relates to a method for manufacturing a plated steel wire on which is formed a zinc alloy plating layer having a multilayer structure, the method comprising: a first plating step for galvanizing a steel wire to form a Zn-Fe alloy layer on the steel wire; and a second plating step for zinc alloy plating the galvanized steel wire obtained from the first plating step in a zinc alloy plating bath to form a zinc alloy plating layer. The present invention also relates to a plated steel wire on which is formed a zinc alloy plating layer having a multilayer structure, the plated steel wire being characterized by comprising: a steel wire; and a zinc alloy plating layer plated on the steel wire and having a multilayer structure, wherein the zinc alloy plating layer comprises a first layer including at least one structure among a Zn-Fe structure and a Zn-Fe-Al structure, a second layer including a Zn-Fe-Al structure and at least one structure among a Zn structure, a Zn-Al structure, and a Zn-Al-Mg-Fe structure, and a third layer including at least three among a Zn structure, a Zn-Al-Mg structure, an Mg-Zn structure, and a Zn-Al structure.

Description

Plating steel wire with a zinc alloy plating layer formed of a multilayer structure and a method of manufacturing the same

The present invention relates to a plated steel wire having a zinc alloy layer formed of a multi-layer structure and a manufacturing method thereof, and more particularly to a mooring steel rope, a hoisting steel rope, an industrial steel wire and a bridge. Zinc alloy, which is used in cables, etc., and has a multi-layered zinc alloy plating layer in which alloy phases composed of elements such as zinc, aluminum, magnesium, and iron are dispersed, and has excellent corrosion resistance and fatigue resistance. It relates to a plated steel wire and a method for producing the plated layer formed.

Hot dip galvanized steel wires have been used in mooring steel ropes, hoisting steel ropes, industrial steel wires and cable cables for offshore oil and gas production facilities. The main factors affecting the service life of steel ropes and cables used for this purpose are the corrosion and fatigue properties of the plated steel wire.

Hot-dip galvanized or Zn-Al-plated steel wire is used for steel ropes and cables, but high strength and long life are required at the same time due to the recent weight reduction. However, when strength of steel ropes and cables is increased, cracks are easily generated in the plating alloy layer during cold drawing, and thus, corrosion resistance and fatigue characteristics are deteriorated.

Although the steel rope and cable are known to have excellent corrosion resistance when plating with Zn-Al-Mg, most of them are applied to steel sheets, and there are problems in cold drawing process as well, and wear resistance is inferior to that of molten zinc.

In addition, the steel wire for steel rope is made through a wire drawing process after hot-dip alloy plating, if the wire workability is not good peeling of the plating layer, there is a problem that the fatigue properties are lowered. Therefore, it is important to secure the ductility and wear resistance of the plated steel wire at the same time.

Steel ropes and cables may be composed of a plurality of wires. Thus, steel ropes and cables composed of a plurality of wires tend to cause corrosion quickly due to a loss of plating layer due to wear between the wires during use. Accordingly, there is a demand for plating characteristics having excellent corrosion resistance and excellent wear resistance.

The present invention has been created to solve the above-mentioned problems, and more particularly, it is used in mooring steel rope, hoisting steel rope, industrial steel wire and bridge cable. As a zinc alloy plating layer in which alloy phases composed of elements such as zinc, aluminum, magnesium, and iron are dispersed in a multilayered structure, a plated steel wire having a zinc alloy plated layer formed of a multilayered structure having excellent corrosion resistance and fatigue resistance and its manufacture It is about a method.

Plating steel wire formed with a zinc alloy layer formed of a multi-layer structure of the present invention for solving the above problems is a steel wire; and the zinc alloy plated layer formed on the steel wire, a multilayer structure; Silver comprises a first layer comprising at least one or more of Zn-Fe, Zn-Fe-Al structure, and Zn-Fe-Al structure, Zn, Zn-Al, Zn-Al-Mg-Fe A second layer comprising at least one of the tissues and a third layer comprising at least three or more of the Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al tissues; It is characterized by. Plating steel wire with a zinc alloy plating layer formed of a multilayer structure.

The composition of the zinc alloy plating layer of the plated steel wire having a zinc alloy layer formed of a multilayer structure of the present invention for solving the above problems is Al: 0.3 or more to 2.0% by weight, Mg: 0.3 or more to 1.5 or less by weight, The remainder contains Zn and unavoidable impurities, the sum of Al and Mg is from 0.6 to 3.5% by weight, and the ratio of Al to Al / Mg (Al / (Al + Mg)) is from 0.3 to 0.70. It is preferable.

The composition of the zinc alloy plating layer of the plated steel wire with a zinc alloy layer formed of a multilayer structure of the present invention for solving the above problems is Al: 0.3 or more to 3.5% by weight, Mg: 0.3 or more to 3.0 or less by weight, The remainder contains Zn and unavoidable impurities, the sum of Al and Mg is 0.6 or more and 6.5 or less by weight, and the ratio of Al to Al and Mg (Al / (Al + Mg)) is 0.3 or more and 0.70. It is preferable.

The ratio of the thickness of the first layer and the thickness of the second layer to the thickness of the zinc alloy plated layer of the plated steel wire having the zinc alloy layer having the multilayer structure of the present invention for solving the above problems is 0.2 or more to 0.6. Preferably, the zinc alloy plating layer may include any one of Bi or Sb, or Bi and Sb, and each of Bi and Sb is preferably less than 1.0 wt%.

In the method for manufacturing a plated steel wire having a zinc alloy layer formed of a multilayered structure of the present invention for solving the above-mentioned problems, Zn-Fe is coated on the steel wire by galvanizing steel wire in a zinc plating bath having Zn of 98% by weight or more. A first plating step of forming an alloy layer; The galvanized steel wire passed through the first plating step, Al: 0.3 or more to 2.0% by weight, Mg: 0.3 or more to 1.5% by weight, the rest includes Zn and unavoidable impurities, the sum of Al and Mg is 0.6 or more A zinc alloy plating layer is applied to the zinc plated steel wire by performing zinc alloy plating in a zinc alloy plating bath having a weight ratio of less than or equal to 3.5% by weight and an Al ratio (Al / (Al + Mg)) to a sum of Al and Mg of 0.30 or more and 0.70 or less. A second plating step of forming; and the zinc alloy plating layer formed through the second plating step, the first layer including at least one of Zn-Fe and Zn-Fe-Al structures. And a second layer comprising a Zn-Fe-Al structure and comprising at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures, and Zn, Zn-Al-Mg, Mg And a third layer comprising at least three or more of the -Zn and Zn-Al tissues. Will.

The zinc alloy plating bath of the method for manufacturing a plated steel wire having a zinc alloy layer formed of a multi-layer structure of the present invention for solving the above-described problems, any one of Bi or Sb, or Bi and Sb together, Bi and Sb is It is preferably included in less than 1.0% by weight each.

In the method for manufacturing a plated steel wire having a zinc alloy layer formed of a multilayered structure of the present invention for solving the above-mentioned problems, Zn-Fe is coated on the steel wire by galvanizing steel wire in a zinc plating bath having Zn of 98% by weight or more. A first plating step of forming an alloy layer; The galvanized steel wire passed through the first plating step, Al: 0.3 or more to 3.5% by weight, Mg: 0.3 or more to 3.0% by weight, the rest includes Zn and unavoidable impurities, the sum of Al and Mg is 0.6 or more Zinc alloy plating in a zinc alloy plating bath having a weight ratio of less than or equal to 6.5% by weight, and an Al ratio (Al / (Al + Mg)) to a sum of Al and Mg of 0.30 or more and 0.70 or less. A second plating step of forming; and the zinc alloy plating layer formed through the second plating step, the first layer including at least one of Zn-Fe and Zn-Fe-Al structures. And a second layer comprising a Zn-Fe-Al structure and comprising at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures, and Zn, Zn-Al-Mg, Mg And a third layer comprising at least three or more of the -Zn and Zn-Al tissues. Will.

The method for manufacturing a plated steel wire having a zinc alloy layer formed of a multilayered structure of the present invention for solving the above-mentioned problems is to cold draw a zinc alloy plated steel wire formed through the second plating step at a processing amount of 90% or less. It is preferable to further include a drawing process, and the zinc alloy plating bath, Bi or Sb, or Bi and Sb together, it is preferable that Bi and Sb are each included less than 1.0% by weight.

The zinc alloy plating layer having a multilayer structure of the present invention includes a Zn-Fe-Al structure and a first layer including at least one of Zn-Fe and Zn-Fe-Al structures, and Zn, Zn-Al. A second layer comprising at least one of Zn-Al-Mg-Fe tissues and at least three or more of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al tissues; Including three layers, it has excellent corrosion resistance and fatigue resistance, and has the advantage of providing a plated steel wire having excellent cold workability.

The first layer of the zinc alloy plating layer can improve the steel wire and bonding force through the Zn-Fe structure, the second layer of the zinc alloy plating layer is Zn, Zn-Al, Zn-Al-Fe, Zn-Al-Mg-Fe It can exhibit excellent wear resistance and corrosion resistance through the structure, the third layer 23 of the zinc alloy plating layer has the advantage that can exhibit excellent corrosion resistance through Zn, Zn-Al-Mg, Mg-Zn, Zn-Al structure.

1 is a view showing a plated steel wire having a zinc alloy plated layer formed of a multilayer structure according to an embodiment of the present invention.

2 is a view showing a zinc alloy plating layer formed through a zinc alloy plating bath having a composition of Zn, Al-0.3 wt% and Mg-0.3 wt% according to an embodiment of the present invention.

3 is a view illustrating a zinc alloy plating layer formed through a zinc alloy plating bath having a composition of Zn, Al-0.9 wt% and Mg-0.8 wt% according to an embodiment of the present invention.

4 is a view showing a zinc alloy plating layer formed through a zinc alloy plating bath having a composition of Zn, Al-1.9 weight% and Mg-1.5 weight% according to an embodiment of the present invention.

5 is a view showing a zinc alloy plating layer formed through a zinc alloy plating bath having a composition of Zn, Al-2.5 wt% and Mg-2.0 wt% according to an embodiment of the present invention.

6 is a view illustrating a zinc alloy plating layer formed through a zinc alloy plating bath having a composition of Zn, Al-5.0 wt% and Mg-5.0 wt% according to an embodiment of the present invention.

7 is a table showing the chemical composition of the steel wire according to an embodiment of the present invention.

8 is a result of performing a salt spray test by changing the Al and Mg content of the zinc alloy plating bath according to an embodiment of the present invention.

Figure 9 shows a graph measuring the corrosion rate by changing the Al and Mg content of the zinc alloy plating bath according to an embodiment of the present invention.

10 is a result table of performing a salt test by changing the Al and Mg content of the zinc alloy plating bath, and the amount of fresh processing according to an embodiment of the present invention.

11 is a table showing the results of the salt spray test by changing the Al and Mg content of the zinc alloy plating bath, and the amount of fresh processing according to an embodiment of the present invention.

12 is, according to an embodiment of the present invention, the first plating step, the second plating step (Zn, Al-0.9 weight%, Mg-0.8 weight%), the wire processing step (90% wire processing amount) It is a figure which shows a plating steel wire.

The present invention is used in mooring steel ropes, hoisting steel ropes, industrial steel wires and cables for bridges, and alloy phases composed of elements such as zinc, aluminum, magnesium, and iron. As the zinc alloy plated layer is dispersed in a multi-layer structure, and relates to a plated steel wire formed with a zinc alloy plated layer formed of a multi-layer structure excellent in corrosion resistance and fatigue resistance and a method of manufacturing the same.

Plating steel wire with a zinc alloy plated layer formed of a multilayer structure of the present invention can be used for the same color and color. The same color is used for cables, ropes and wires that need to be cold drawn after zinc alloy plating, and the color can be used for cables, ropes and wires that do not need to be cold drawn after zinc alloy plating. The same color and color for the production is produced by varying the composition ratio of the zinc alloy plating bath in the second plating step to be described later. For coloring, the second plating step may be the final process, but for coloring, the same is used after the cold drawing process. The same color includes mooring steel ropes, offshore crane ropes, land crane ropes and mining ropes. ) And bridge ropes and cables.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a plated steel wire having a zinc alloy plating layer formed of a multilayer structure of the present invention is plated on a steel wire 10 and the steel wire 10, and includes a zinc alloy plating layer 20 having a multilayer structure.

The steel wire 10 is made of a steel wire used for mooring steel rope, hoisting steel rope, industrial steel wire and bridge cables.

The zinc alloy plating layer 20 has a multilayer structure, and includes a first layer 21 including Zn-Fe and Zn-Fe-Al structures, and a first layer 21 and Zn-Fe-Al structures. A second layer 22 including at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures, and Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al structures. It may comprise a third layer 23 comprising at least three or more of the tissue.

 The first layer 21 may include a Zn-Fe structure, but in the second plating step to be described later, Zn-Fe structure may be removed so that only Zn-Fe-Al structure may be left, and Zn-Fe and Zn-Fe-Al tissue may remain at the same time.

In the zinc alloy plating layer 20, the ratio of the first layer 21 and the second layer 22 is preferably 20% or more and 60% or less. That is, the ratio of the first layer 21 and the second layer 22 to the zinc alloy plating layer 20 may be 0.2 or more and 0.6 or less. Specifically, the ratio of the thickness of the first layer 21 to the thickness of the second layer 22 with respect to the thickness of the zinc alloy plating layer 20 may be 0.2 to 0.6 or less. ((Thickness of the first layer 21 + thickness of the second layer 22) / the value of the thickness of the zinc alloy plating layer 20 may be made of 0.2 or more to 0.6.)

When the ratio of the first layer 21 and the second layer 22 in the zinc alloy plating layer 20 is less than 20%, plating adhesion and abrasion resistance are insufficient, and in the zinc alloy plating layer 20, the first If the ratio of the layer 21 and the second layer 22 is greater than 60%, cracking of the plating layer may occur. Therefore, the ratio of the first layer 21 and the second layer 22 in the zinc alloy plating layer 20 is preferably 20% or more and 60% or less.

In the case of using a plated steel wire for the same color to be cold drawn after zinc alloy plating, the composition of the zinc alloy plating layer 20 is Al: 0.3 or more and 2.0 or less weight%, Mg: 0.3 or more and 1.5 or less weight%, and the rest. Is Zn and unavoidable impurities, the sum of Al and Mg is not less than 0.6 and not more than 3.5, and the ratio of Al to Al and Mg (Al / (Al + Mg)) is not less than 0.3 and not more than 0.70. have.

In the case of using a plated steel wire for coloring that does not need to be cold drawn after zinc alloy plating, the composition of the zinc alloy plating layer 20 is Al: 0.3 or more and 3.5 or less weight%, Mg: 0.3 or more and 3.0 or less weight%, The remainder contains Zn and unavoidable impurities, and the sum of Al and Mg is 0.6 or more and 6.5 or less, and the ratio of Al to Al and Mg (Al / (Al + Mg)) is 0.3 or more and 0.70 days. Can be.

Here, the sum of Al and Mg means the aluminum content and the magnesium content, and the ratio of Al to the sum of Al and Mg means the ratio of the aluminum content to the sum of the aluminum content and the magnesium content.

In the case of using a plated steel wire for the same color that needs to be cold drawn after zinc alloy plating, the corrosion resistance is insufficient when Al is less than 0.3% by weight, and when it exceeds 2.0% by weight, the cold drawing property is lowered. It is preferable to contain 0.3 weight% or more and 2.0 weight% or less. When the plated steel wire is used for coloring that does not need to be cold drawn after zinc alloy plating, the corrosion resistance is insufficient when Al is less than 0.3% by weight, and when it exceeds 3.5% by weight, the corrosion resistance is insignificant. Since plating workability also falls due to the Ross problem, Al preferably contains 0.3 to 3.5% by weight.

When the plated steel wire is used for the same color for cold drawing after zinc alloy plating, the corrosion resistance is insufficient when Mg is less than 0.3% by weight, and when the content exceeds 1.5% by weight, the cold workability is deteriorated. It is preferable to contain 0.3 to 1.5 weight% of silver. When the plated steel wire is used for coloring that does not need to be cold drawn after zinc alloy plating, corrosion resistance is insufficient when Mg is less than 0.3% by weight, and when it exceeds 3.0% by weight, the corrosion resistance is insignificant and plating workability Since this worsens, it is preferable that Mg content contains 0.3 to 3.0 weight%.

Since Al and Mg are both elements which improve the corrosion resistance of the plating layer, when the content of these elements is increased, the corrosion resistance is improved. However, when the plated steel wire is used for the same color that needs to be cold drawn, the corrosion resistance is insufficient when the sum of Al and Mg content is less than 0.6 wt%, and the cold workability is deteriorated when it exceeds 3.5 wt%. The sum is preferably 0.6 to 3.5% by weight. In the case of using a plated steel wire for coloring that does not require cold drawing after zinc alloy plating, corrosion resistance is insufficient when the sum of Al and Mg content is less than 0.6% by weight, and the effect of improving corrosion resistance is not large when it exceeds 6.5% by weight. Therefore, the sum of Al and Mg content in the plating bath is preferably 0.6 to 6.5% by weight.

In addition, in the case of using the plated steel wire for the same color that needs to be cold drawn and the use of the plated steel wire for the color that does not need to be cold drawn, the Al content is the sum of the Al content and the Mg content. If the ratio Al / (Al + Mg) is less than 0.3, oxidation of the plating bath occurs severely with the increase of Mg content, and defects of the plating layer are caused due to floating of intergranular compound particles of dross type MgZn _{2 in} the plating bath. Can be generated. When Al / (Al + Mg), which is the ratio of Al content to the sum of Al content and Mg content, exceeds 0.70, the ratio of the Mg alloy layer to the plating layer may decrease, which may lower corrosion resistance. Therefore, it is preferable to keep Al / (Al + Mg) at 0.3 or more and 0.70 or less.

The plated steel wire formed with a zinc alloy plated layer formed of the multilayer structure of the present invention described above is as follows.

In the method of manufacturing a plated steel wire having a zinc alloy plating layer formed of a multilayer structure, the steel wire 10 may include a first plating step of plating in a zinc plating bath, and a first plating step of plating a galvanized steel wire in a zinc alloy plating bath. It includes two plating steps.

The first plating step is to form a Zn-Fe alloy layer on the steel wire 10 by galvanizing the steel wire 10 in a zinc plating bath having Zn of 98% by weight or more. The Zn-Fe alloy layer is formed by reacting Zn with the steel wire 10 containing Fe. Here, the composition of the galvanizing bath is preferably Zn is formed in more than 98% by weight. If the composition of Zn is less than 98% by weight, the appearance quality is insufficient due to impurities, and since the impurities are dissolved in the second plating step described later to contaminate the zinc alloy plating bath, the content of Zn is maintained at 98% by weight or more.

The second plating step is a step of forming a zinc alloy plating layer by zinc alloy plating the zinc plated steel wire passed through the first plating step in a zinc alloy plating bath. In the second plating step, the composition of the zinc alloy plating bath is the zinc alloy according to the case of using the plated steel wire for the same color for cold drawing and the case of using the plated steel wire for the coloring without the cold drawing process. The composition of the plating bath is formed differently.

In the case of using a plated steel wire for the same color to be cold drawn, the composition of the zinc alloy plating bath is Al: 0.3 or more and 2.0 or less by weight, Mg: 0.3 or more and 1.5 or less by weight, and the rest is Zn and unavoidable impurities. It includes, and the sum of Al and Mg is 0.6 or more to 3.5 or less by weight, and the ratio of Al to Al (M / (Al + Mg)) to the sum of Al and Mg is 0.30 or more and 0.70 or less.

In the case of using a plated steel wire for coloring that does not require cold drawing, the composition of the zinc alloy plating bath is Al: 0.3 or more and 3.5 or less weight%, Mg: 0.3 or more and 3.0 or less weight%, and the rest is Zn and unavoidable impurities. It includes, and the sum of Al and Mg is 0.6 or more to 6.5 or less by weight, the ratio of Al to Al (M / (Al + Mg)) to the sum of Al and Mg is formed from 0.30 to 0.70 or less.

As such, after the first plating step and the second plating step, the zinc alloy plating layer 20 having a multi-layer structure is formed on the steel wire 10. In detail, the zinc alloy plating layer 20 includes a first layer 21 including Zn-Fe and Zn-Fe-Al structures, and a Zn-Fe-Al structure. At least three of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al tissues, and a second layer 22 including at least one of Zn-Al and Zn-Al-Mg-Fe tissues. It may comprise a third layer 23 comprising more than one tissue.

Looking at the process of forming the multi-layer structure of the zinc alloy plating layer 20 is as follows. Part of the Zn-Fe alloy layer formed in the first plating step is reacted with Al and Mg in the second plating step, the second comprising a structure consisting of at least three or more of Fe, Mg, Al, Zn Layer 22 will be formed.

That is, the Zn-Fe alloy layer formed in the first plating step is formed of the first layer 21 and the second layer 22 through the second plating step. Here, the ratio of the Zn-Fe alloy layer of the first plating step is formed at an appropriate level so as to obtain the first layer 21 and the second layer 22 in the second plating step.

The third layer 23 is formed by reacting Zn, Mg, and Al according to the composition of the zinc alloy plating bath of the second plating step, and includes a structure composed of Zn, Mg, and Al.

Specifically, the first layer 21 is formed of at least one or more of the Zn-Fe, Zn-Fe-Al structure, the second layer 22 includes a Zn-Fe-Al structure, Zn At least one of Zn-Al and Zn-Al-Mg-Fe structures is formed, and the third layer 23 is formed of at least 3 of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al structures. More than one tissue is formed.

As described above, the zinc alloy plating layer 20 has a multilayer structure through the first plating step and the second plating step, but the zinc alloy plating layer may be formed according to the composition of the zinc alloy plating bath of the second plating step. 20) may vary in form.

2 to 6 show the zinc alloy plating layer 20 formed by changing the content of Al and Mg of the zinc alloy plating bath according to an embodiment of the present invention.

FIG. 2 shows the zinc alloy plating bath 20 by forming the zinc alloy plating bath in Zn, Al-0.3 weight% and Mg-0.3 weight%, and FIG. 3 shows the zinc alloy plating bath in Zn, Al-. 0.9 wt%, Mg-0.8 wt% to form the zinc alloy plating layer 20, Figure 4 shows the zinc alloy plating bath is composed of Zn, Al-1.9 wt%, Mg-1.5 wt% The zinc alloy plating layer 20 is formed.

2 to 4, as the Al and Mg contents of the zinc alloy plating bath of the second plating step are increased, the Zn-Fe alloy layer formed in the first plating step reacts with Al, and Zn-Fe More of the second layer 22, including at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe, is formed, and the Zn-Fe alloy layer is reduced. I can do it.

As described above, when the Zn-Fe alloy layer decreases and the second layer 22 increases, the difference in the plastic strain coefficient between the steel wire 10 and the first layer 21 during cold drawing is reduced. It is possible to suppress the occurrence of cracks between the 10 and the first layer 21 to improve the cold workability.

In addition, the second layer 22 includes a Zn-Fe-Al structure in which a Zn-Fe alloy layer reacts with Al, and includes at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures. It has excellent abrasion resistance, including the composed tissue. Accordingly, as the second layer 22 increases, wear resistance may be improved while corrosion resistance is excellent.

In addition, the third layer 23 is formed to include a structure consisting of Zn, Mg, Al, at least three or more of the Zn, Zn-Al-Mg, Mg-Zn, Zn-Al tissue is formed . In the third layer 23, phases such as Zn-Al-Mg, Mg-Zn, Zn-Al, etc. may be increased, thereby greatly improving corrosion resistance.

 FIG. 5 shows the zinc alloy plating bath 20 by forming the zinc alloy plating bath in Zn, Al-2.5 wt% and Mg-2.0 wt%, and FIG. 6 shows the zinc alloy plating bath in Zn, Al−. 5.0 wt%, Mg-5.0 wt% is to form the zinc alloy plating layer 20.

The Zn-Fe structure of the first layer 21 remains in the first layer 21 until the Al content is 0.9% by weight, but when the Al content increases to 1.9% by weight, the Zn-Fe structure remains locally at the interface.

Referring to FIG. 5, when the Al content is increased to 2.5% by weight, the Zn-Fe structure of the first layer 21 decreases considerably, and the Al structure concentration of the first layer 21 (Zn-Fe-Al). Tissue concentration) increases. In addition, referring to FIG. 6, when the Al content is further increased to 3.5% by weight, an area in which a high concentration of Al structure (Zn-Fe-Al structure) is present at the interface is increased. As such, when the Al structure concentration (Zn-Fe-Al tissue concentration) increases in the first layer 21, the bonding force between the steel wire 20 and the first layer 21 is lowered. In addition, an increase in the content of Mg leads to a decrease in the ductility of the plating layer.

As such, when the content of Al and Mg in the zinc alloy plating bath is increased, the bonding force between the steel wire 20 and the first layer 21 is lowered, thereby reducing cold workability and freshness. That is, when the Zn-Fe structure in the first layer 21 disappears and the concentration of the Al structure (Zn-Fe-Al structure concentration) is increased, the bonding strength of the interface is lowered, which causes cracks at the interface during the drawing process. Will occur.

Therefore, the same color plating steel wire which needs to be cold drawn after the first plating step and the second plating step has a composition of the zinc alloy plating bath of the second plating step, wherein Al is 2.0 or less by weight and Mg is 1.5 It is preferable to set it as the weight% below.

Specifically, in the case of using a plated steel wire for the same color that needs to be cold drawn after zinc alloy plating, when Al is less than 0.3% by weight in the composition of the zinc alloy plating bath, the corrosion resistance is insufficient, and when it exceeds 2.0% by weight Since cold wire workability falls, it is preferable that Al is 0.3 to 2.0 weight%.

In the case of using a plated steel wire for coloring that does not require cold drawing after zinc alloy plating, corrosion resistance is insufficient when Al is less than 0.3 wt% in the composition of the zinc alloy plating bath, and when it exceeds 3.5 wt% Since the improvement of the process is insignificant and plating workability also falls due to the dross problem, it is preferable that Al is 0.3 to 3.5 weight%.

In the case of using a plated steel wire for the same color that needs to be cold drawn after zinc alloy plating, corrosion resistance is insufficient when Mg is less than 0.3 wt% in the composition of the zinc alloy plating bath, and cold workability is greater than 1.5 wt%. Since the content is lowered, the Mg content is preferably 0.3 to 1.5% by weight. In the case of using a plated steel wire for coloring that does not need to be cold drawn after zinc alloy plating, corrosion resistance is insufficient when Mg is less than 0.3 wt% in the composition of the zinc alloy plating bath, and when it exceeds 3.0 wt% Since the improvement is insignificant and the plating workability deteriorates, the content of Mg is preferably 0.3 to 3.0% by weight or less.

Since Al and Mg are both elements which improve the corrosion resistance of the plating layer, when the content of these elements is increased, the corrosion resistance is improved. However, in the case of using a plated steel wire for the same color to be cold drawn, the corrosion resistance is insufficient when the sum of Al and Mg weight% in the zinc alloy plating bath is less than 0.6 wt%, and when it exceeds 3.5%, the cold workability is deteriorated. Since the sum of Al and Mg content is preferably 0.6 to 3.5% by weight. In the case of using a plated steel wire for coloring that does not require cold drawing after zinc alloy plating, when the sum of Al and Mg weight% in the zinc alloy plating bath is less than 0.6 weight%, the corrosion resistance is insufficient, and when it exceeds 6.5% Since the effect of improving corrosion resistance is not great, the sum of Al and Mg contents is preferably 0.6 to 6.5% by weight.

In addition, both the case of using a plated steel wire for the same color that needs to be cold drawn and the case of using a plated steel wire for the coloration that does not need to be cold drawn, the content of Al and Mg in the zinc alloy plating bath If Al / (Al + Mg), which is the ratio of Al content to the sum, is less than 0.3, oxidation of the zinc alloy plating bath occurs severely with increasing Mg content, and intergranular compound particles of Dg form of MgZn ₂ Floating causes defects in the plating layer. When Al / (Al + Mg), which is the ratio of Al content to the sum of Al content and Mg content in the zinc alloy plating bath, exceeds 0.70, the ratio of the Mg alloy layer to the plating layer may decrease, which may reduce corrosion resistance. have. Therefore, it is preferable to keep Al / (Al + Mg) at 0.3 or more and 0.70 or less.

In the method of manufacturing a plated steel wire having a zinc alloy plating layer formed of a multilayer structure of the present invention, the temperature of the zinc plating bath in the first plating step and the zinc alloy plating bath in the second plating step is 430 ° C. or more and 470 ° C. or less. It is preferred to remain at. When the temperature of the zinc plating bath and the zinc alloy plating bath is less than 430 ° C., the viscosity of the molten alloy is high, so that the plating appearance becomes rough. And the temperature of the zinc alloy plating bath is preferably maintained at 430 ℃ or more to 470 ℃ or less.

In the case where the plated steel wire is used for the same color to be cold drawn after zinc alloy plating, the method of manufacturing a plated steel wire having a zinc alloy plated layer having a multilayer structure according to the present invention is performed by the zinc plating. It may further comprise a wire drawing step of cold drawing the steel wire to a processing amount of less than 90%. Here, the amount of drawn processing is (1- (fresh plated steel wire diameter / plated steel wire diameter) ² ) x 100.

In the case where the cold working amount of cold drawing exceeds 90%, the fresh working amount is preferably 90% or less because not only the salt quality related to the fatigue life is lowered but also cracking occurs in the plating layer. (When cold drawing is not performed, the diameter of the drawn steel wire is equal to the diameter of the plated steel wire, so that the amount of drawn wire becomes 0%. That is, the amount of drawn wire can be made from more than 0% to 90%.)

Hereinafter, specific embodiments of the present invention will be described in detail. Of course, the following examples are provided to aid the understanding of the present invention, and do not limit the present invention.

Example 1

By Example 1 was confirmed the corrosion resistance according to the Al and Mg content of the zinc alloy plating bath.

The steel plate 10 having a diameter of 8 mm and having the components shown in Table 1 of FIG. 7 is zinc plated in the first plating step, and the second plating step in the zinc alloy plating bath having the composition of Table 2 of FIG. 8. Seven samples were prepared by the following procedure.

Here, the temperature of the galvanizing bath to perform the first plating step was 450 ℃, immersed in the galvanizing bath for 23 seconds, the composition of the galvanizing bath was Zn 99.6% by weight, the rest contained impurities. The composition of the second plating step is as shown in Table 2 of Figure 8, the temperature of the zinc alloy plating bath was 445 ℃, the immersion time was 20 seconds. Gas wiping used nitrogen gas.

 Corrosion resistance evaluation was performed by the salt spray test (salt spray standard test according to KS-C-0223) and electrochemical test (Electrochemical test). The salt spray test is to measure the time elapsed until the area where red blue occurs on the surface of the specimen to 5%, the results are shown in Table 2 (Salt Pray) of FIG. Electrochemical test (Electrochemical test) was evaluated using a potentiostat (Potentiostat), the results are shown in FIG. Specifically, Figure 9 is a graph showing the corrosion rate according to the Al and Mg content means that the corrosion rate is lower the higher the corrosion rate.

Referring to Table 2 of FIG. 8, when the sum of Al content and Mg content (hereinafter referred to as “Al + Mg”) is 0.2 wt% or less, the salt spray test showed relatively low corrosion resistance at 650 hours, and Al + Mg. From this 0.6% by weight, the salt spray test showed 2243 hours of excellent corrosion resistance. In particular, Al + Mg was 3.4 wt%, the salt spray test was 4625 hours, it was shown that the corrosion resistance is very excellent. If Al + Mg is more than 4.5% by weight, the increase in salt spray time is slight. This seems to be due to the coarsening of the Al-Zn binaries.

Looking at the corrosion resistance corrosion rate of Figure 9, similar to the results of the salt spray test shows that the corrosion resistance Al + Mg content is improved to 3.4% by weight, but shows a slight improvement from 6.8% by weight. This means that excellent corrosion resistance is obtained in an Al + Mg content of 0.6 ~ 6.8% by weight.

Example 2

According to Example 1, seven samples of the zinc alloy plated steel wire that passed the second plating step were drawn at 85%, 90%, and 92% fresh throughput to prepare 21 samples, and a salt test and a salt spray test were performed. To evaluate the level of quality. Here, the amount of drawn processing is calculated as (1- (fresh plated steel wire diameter / plated steel wire diameter) ² ) x 100. At this time, the drawing speed was 5 m / sec, the average reduction rate per die was 19%.

For the salt test, the specimen length is 8 inches and the torsional speed is tested 60 times per minute. The salt test measures the number of times of twisting while rotating the wire 360 degrees until the steel wire is broken. If the salt test value is high, the fatigue resistance is good. If the salt test value is low, the fatigue resistance is poor. The salt spray test is for evaluating the corrosion resistance as described above. The salt test results of Example 2 are shown in Table 3 of FIG. 10, and the salt spray test results of Example 2 are shown in Table 4 of FIG.

As shown in Table 3 of FIG. 10, saline quality was obtained in the Mg + Al content of 0.6% by weight up to 90%. Excellent salt characteristics mean excellent fatigue resistance. However, it can be seen that the quality of the salt is reduced to 8 or less at 92% of the fresh working amount. In particular, when the Mg + Al content exceeds 4.5% by weight, the salt quality was remarkably degraded. In addition, in Table 4 of FIG. 11, when the salt spray test time (corrosion resistance) increased to 92%, a significant decrease was observed in all samples (Samples No 2 to 7) having an Mg + Al content of 0.6% by weight or more.

This phenomenon was generated by cracking in the surface of the zinc alloy plating layer 20 or steel wire 10 at 92% of the fresh working amount, and propagating the crack into the base metal. At 90% freshness, all samples with Mg + Al content ranging from 0.6% to 3.4% by weight were good for more than 1800 hours. Referring to FIG. 12, the fresh plated steel wire was well distributed in alloy phases in the plating. It can be seen that there is no crack. Therefore, the freshness is less than 90%.

The above-described plated steel wire and a method of manufacturing the zinc alloy plated layer formed of the multilayer structure of the present invention have the following effects.

The zinc alloy plating layer 20 having a multilayer structure of the present invention includes the first layer 21 and Zn-Fe-Al structure including at least one of Zn-Fe and Zn-Fe-Al structures. And a second layer 22 including at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures, and Zn, Zn-Al-Mg, Mg-Zn, and Zn. And the third layer 23 including at least three or more of -Al tissues.

 The first layer 21 may strongly bond the steel wire 10 and the zinc alloy plating layer 20 through a Zn-Fe structure (or Zn-Fe-Al structure) having improved ductility by solid solution of Al. There is an advantage. In the Zn-Fe structure (or Zn-Fe-Al structure) in which Al is dissolved, a Zn-Fe layer formed by reacting Zn and steel of the steel wire 10 in the first plating step is formed of Al in the second plating step. It is a softened organization formed by employment. As described above, the Aln-solidified Zn-Fe structure (or Zn-Fe-Al structure) may improve the bonding strength between the steel wire 10 and the zinc alloy plating layer 20.

The second layer 22 includes a structure composed of at least three of Fe, Mg, Al, and Zn by reacting the Zn-Fe layer formed in the first plating step with Al and Mg in the second plating step. It is to make a plating layer made of. Specifically, the second layer 22 may include a Zn-Fe-Al structure, and may include at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures. The second layer 22 has excellent wear resistance and corrosion resistance.

 When Al and Mg are added, Al and Mg react with the Zn-Fe alloy layer, which is a hardened structure produced during pure hot dip galvanizing, to form a new ductile structure (structure in which Zn-Al or Zn-Al-Fe phase is dispersed). This is because the hardened tissue is lost while making.

The third layer 23 includes a tissue composed of at least one of Mg, Al, and Zn, and specifically, at least three or more of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al. It involves the organization. The third layer 23 can exhibit excellent corrosion resistance through Zn, Zn-Al-Mg, Mg-Zn, Zn-Al structure.

As such, the present invention includes the first layer 21, the second layer 22, and the third layer 23, so that the bonding force with the steel wire 10 is strong, and excellent corrosion resistance and wear resistance are achieved. It can exhibit the characteristics, through which there is an advantage to provide a plated steel wire excellent in corrosion resistance and fatigue resistance.

In addition, in the case of using a plated steel wire for the same color that needs to be cold drawn after zinc alloy plating, the cold drawing processability can be improved, and the cold drawing process can be carried out at 90% or less, so that the corrosion resistance and abrasion resistance can be improved. There is an advantage to improve.

According to another embodiment of the present invention, the composition of the zinc alloy plating bath of the second plating step may include any one of Bi (bismuth) or Sb (antimony), or Bi and Sb. At this time, the content of Bi and the content of Sb are each configured to be less than 1.0% by weight.

When the Bi content and the Sb content are added below 1.0 wt%, respectively, the surface tension and viscosity of the molten zinc alloy are lowered to reduce the surface roughness, and the dross-type MgZn in the plating bath is reduced. _{2 The} surface defects (lumpy, etc.) caused by the intermetallic compound suspension are reduced, so that uniform surface roughness can be obtained. If the content of Bi and Sb exceeds 1.0% by weight, wear characteristics are significantly increased (acccelerated material wear), thereby damaging the zinc alloy plating bath and the surface of the plating layer is not preferable.

The zinc alloy plating layer 20 may include any one of Bi or Sb, or Bi and Sb, and each of Bi and Sb may be included in less than 1.0 wt%. In the composition of the zinc alloy plating bath, any one of Bi (bismuth) or Sb (antimony), or Bi and Sb together, the first layer 21 is formed of at least one of Zn-Fe and Zn-Fe-Al structures. It may comprise one or more tissues, the second layer 22 comprises a Zn-Fe-Al tissue, and comprises at least one tissue of Zn, Zn-Al, Zn-Al-Mg-Fe tissue The third layer 23 may include a tissue including at least one of Bi and Sb in Mg, Al, and Zn. (Specifically, the third layer 23 may include Bi-Mg and Sb-Mg crystal structures, and at least one of Bi and Sb in Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al tissues. In addition, crystal structures such as Zn-Bi and Zn-Sb may be formed on the third layer 23.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and many other modifications may be provided without departing from the scope of the present invention.

Claims (10)

1. In the plated steel wire formed with a zinc alloy plating layer consisting of a multilayer structure,

   Liner;

   Plated on the steel wire, a zinc alloy plated layer made of a multi-layer structure; comprising, the zinc alloy plated layer,

   A first layer comprising at least one of Zn-Fe and Zn-Fe-Al tissues,

   A second layer comprising a Zn-Fe-Al structure and comprising at least one of Zn, Zn-Al, and Zn-Al-Mg-Fe structures,

   A plated steel wire having a zinc alloy plating layer having a multi-layer structure, comprising a third layer including at least three or more of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al structures.
2. The method of claim 1,

   The composition of the zinc alloy plating layer,

   Al: 0.3 or more and 2.0 or less weight%, Mg: 0.3 or more and 1.5 or less weight%, the rest contains Zn and unavoidable impurities,

   The sum of Al and Mg is from 0.6 to 3.5% by weight,

   Plating steel wire with a zinc alloy plated layer formed of a multi-layer structure, characterized in that the ratio of Al (Al / (Al + Mg)) to the sum of Al and Mg is 0.3 or more to 0.70.
3. The method of claim 1,

   The composition of the zinc alloy plating layer,

   Al: 0.3 or more and 3.5 or less weight%, Mg: 0.3 or more and 3.0 or less weight%, the rest contains Zn and unavoidable impurities,

   The sum of Al and Mg is 0.6 or more and 6.5 or less by weight,

   Plating steel wire with a zinc alloy plated layer formed of a multi-layer structure, characterized in that the ratio of Al (Al / (Al + Mg)) to the sum of Al and Mg is 0.3 or more to 0.70.
4. The method of claim 1,

   The ratio of the thickness of the first layer and the thickness of the second layer relative to the thickness of the zinc alloy plating layer is 0.2 or more to 0.6 or less plating steel wire formed with a zinc alloy plating layer having a multi-layer structure.
5. The method of claim 1,

   The composition of the zinc alloy plating layer,

   Any one of Bi or Sb, or Bi and Sb together;

   Bi and Sb is a plating steel wire formed with a zinc alloy plating layer consisting of a multi-layer structure, characterized in that each contained less than 1.0% by weight.
6. In the method of manufacturing a plated steel wire having a zinc alloy layer formed of a multilayer structure,

   A first plating step of galvanizing steel wire in a zinc plating bath having Zn of 98 wt% or more, thereby forming a Zn-Fe alloy layer on the steel wire;

   The galvanized steel wire passed through the first plating step, Al: 0.3 or more to 2.0% by weight, Mg: 0.3 or more to 1.5% by weight, the rest includes Zn and unavoidable impurities, the sum of Al and Mg is 0.6 or more A zinc alloy plating layer is applied to the zinc plated steel wire by performing zinc alloy plating in a zinc alloy plating bath having a weight ratio of less than or equal to 3.5% by weight and an Al ratio (Al / (Al + Mg)) to a sum of Al and Mg of 0.30 or more and 0.70 or less. Forming a second plating step;

   The zinc alloy plating layer formed through the second plating step,

   A first layer comprising at least one or more of the Zn-Fe, Zn-Fe-Al tissue, and Zn-Fe-Al tissue, comprising Zn, Zn-Al, Zn-Al-Mg-Fe tissue And a second layer comprising at least one tissue and a third layer comprising at least three or more tissues of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al tissues. Plated steel wire manufacturing method formed with a zinc alloy plating layer consisting of a multi-layer structure.
7. The method of claim 6,

   The zinc alloy plating bath,

   Any one of Bi or Sb, or Bi and Sb together;

   Bi and Sb is a plating steel wire formed with a zinc alloy plating layer consisting of a multi-layer structure, characterized in that each contained less than 1.0% by weight.
8. In the method of manufacturing a plated steel wire having a zinc alloy layer formed of a multilayer structure,

   A first plating step of galvanizing steel wire in a zinc plating bath having Zn of 98 wt% or more, thereby forming a Zn-Fe alloy layer on the steel wire;

   The galvanized steel wire passed through the first plating step, Al: 0.3 or more to 3.5% by weight, Mg: 0.3 or more to 3.0% by weight, the rest includes Zn and unavoidable impurities, the sum of Al and Mg is 0.6 or more Zinc alloy plating in a zinc alloy plating bath having a weight ratio of less than or equal to 6.5% by weight, and an Al ratio (Al / (Al + Mg)) to a sum of Al and Mg of 0.30 or more and 0.70 or less. Forming a second plating step;

   The zinc alloy plating layer formed through the second plating step,

   A first layer comprising at least one or more of the Zn-Fe, Zn-Fe-Al tissue, and Zn-Fe-Al tissue, comprising Zn, Zn-Al, Zn-Al-Mg-Fe tissue And a second layer comprising at least one tissue and a third layer comprising at least three or more tissues of Zn, Zn-Al-Mg, Mg-Zn, and Zn-Al tissues. Plated steel wire manufacturing method formed with a zinc alloy plating layer consisting of a multi-layer structure.
9. The method of claim 8,

   Zinc alloy plated steel wire formed through the second plating step,

   A method of manufacturing a plated steel wire having a zinc alloy plated layer formed of a multilayer structure, further comprising: a wire drawing step of cold drawing at a 90% or less drawing amount.
10. The method of claim 8,

    The zinc alloy plating bath,

    Any one of Bi or Sb, or Bi and Sb together;

    Bi and Sb is a plating steel wire formed with a zinc alloy plating layer consisting of a multi-layer structure, characterized in that each contained less than 1.0% by weight.

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