JP6880238B2 - Hot-dip plated steel wire and its manufacturing method - Google Patents

Description

The present invention relates to a hot-dip plated steel wire and a method for manufacturing the same.
The present application claims priority based on Japanese Patent Application No. 2017-2433434 filed in Japan on December 20, 2017, the contents of which are incorporated herein by reference.

Hot-rolled steel wire manufactured from hot-rolled wire is descaled from the hot-rolled steel wire, further coated, and then reduced in diameter by plastic processing with a die or roll to perform a plating pretreatment process. After the surface is activated by pickling or flux treatment, it is immersed in a bath of molten metal to form a metal film on the surface of the steel wire, which is manufactured.

The purpose of hot-dip plating is mainly to improve corrosion resistance, where a molten metal film such as zinc and a zinc-aluminum (Al) alloy is formed, and iron corrosion is suppressed by the sacrificial anticorrosive action of zinc. The thicker the coating, the better the corrosion resistance. Further, the corrosion resistance is improved by alloying with Al and other components. In particular, a plating component containing a small amount of Mg as well as Zn and Al can obtain high corrosion resistance. However, the plating component containing a small amount of Mg has a problem that the workability is deteriorated due to the formation of a hard intermetallic compound composed of Zn and Mg. That is, there is a problem that the plating layer is cracked or the plating layer is peeled off before various processing is performed in the post-plating process until the product is produced. For this reason, the hot-dip plated steel wire is required to have corrosion resistance and workability that does not cause plating peeling or cracking during post-processing.

Further, when the plating layer is cracked, the strength and ductility of the plated steel wire may be lowered. In order to ensure the characteristics of the product, the plated steel wire is required to have excellent workability in which the plating layer does not crack during processing.

Therefore, various proposals have been made conventionally for hot-dip plating containing Mg, Zn, and Al to ensure workability and corrosion resistance.

For example, Patent Document 1 proposes plating that improves workability by thinning the alloy layer containing Fe at the interface of the base iron. Patent Document 2 proposes a plating structure in which an intermetallic compound of _{MgZn 2 is dispersed to improve corrosion resistance.} Patent Documents 3 and 4 propose plated wires that limit the β phase to 20% or less and improve processability and corrosion resistance.

However, even with these plated wires, when wire drawing is performed after plating, it is difficult to completely eliminate the occurrence of fine cracks in the plating layer and local peeling of the plating layer, and it is difficult to completely eliminate the plating layer. Fracture starting from the cracks that occurred could reduce strength and ductility.

Japanese Patent Application Laid-Open No. 2003-155549 Japanese Patent Application Laid-Open No. 2002-47548 Japanese Patent Application Laid-Open No. 2002-30404 Japanese Patent Application Laid-Open No. 2002-30405

The present invention has been made in view of the above circumstances, and there is no cracking or peeling of the plating layer when winding or wire drawing is performed, and the corrosion resistance is higher than that of Zn-plated steel wire or Zn-Al hot-dip plated steel wire. It is an object of the present invention to provide a hot-dip plated steel wire obtained from the above, and a method for producing the same.

The gist of the present invention is as follows.
(1) The hot-dip plated steel wire according to one aspect of the present invention includes a steel wire to be plated and a plating layer arranged on the surface of the steel wire to be plated, and the component of the plated layer is mass%. Mg: 0.10% or more and less than 1.00%, Al: 5.0% or more and 15.0% or less, Si: 0% or more and 2.0% or less, Fe: 0% or more and 1.0% or less, Sb: 0% or more and 1.0% or less, Pb: 0% or more and 1.0% or less, Sn: 0% or more and 1.0% or less, Ca: 0% or more and 1.0% or less, Co: 0% or more and 1.0 % Or less, Mo: 0% or more and 1.0% or less, Mn: 0% or more and 1.0% or less, P: 0% or more and 1.0% or less, B: 0% or more and 1.0% or less, Bi: 0 % Or more and 1.0% or less, Cr: 0% or more and 1.0% or less, REM: 0% or more and 1.0% or less, Ni: 0% or more and 1.0% or less, Ti: 0% or more and 1.0% Hereinafter, Zr: 0% or more and 1.0% or less, and Sr: 0% or more and 1.0% or less are contained, and the balance is composed of Zn and impurities. The structure of the plating layer is 90% Zn in mass%. The Zn phase containing the above is 25 to 70% in area ratio, and the area ratio of the Zn phase having a crystal particle size of 2 to 5 μm converted into a circle is 20 to 100% of the Zn phase.
(2) In the hot-dip plated steel wire according to (1) above, the component of the plating layer may contain Si: 0.01% or more and 2.0% or less in mass%.
(3) In the hot-dip plated steel wire according to (1) or (2) above, the component of the plating layer is, in mass%, Fe: 0.01% or more and 1.0% or less, Sb: 0.01. % Or more and 1.0% or less, Pb: 0.01% or more and 1.0% or less, Sn: 0.01% or more and 1.0% or less, Ca: 0.01% or more and 1.0% or less, Co: 0 0.01% or more and 1.0% or less, Mo: 0.01% or more and 1.0% or less, Mn: 0.01% or more and 1.0% or less, P: 0.01% or more and 1.0% or less, B : 0.01% or more and 1.0% or less, Bi: 0.01% or more and 1.0% or less, Cr: 0.01% or more and 1.0% or less, and REM: 0.01% or more and 1.0% or less It may contain one or more selected from the group consisting of the following.
(4) In the hot-dip plated steel wire according to any one of (1) to (3) above, the component of the plating layer is, in mass%, Ni: 0.01% or more and 1.0% or less. One or two selected from the group consisting of Ti: 0.01% or more and 1.0% or less, Zr: 0.01% or more and 1.0% or less, and Sr: 0.01% or more and 1.0% or less. The above may be contained.
(5) The method for producing a hot-dip plated steel wire according to another aspect of the present invention is the method for manufacturing a hot-dip-plated steel wire according to any one of (1) to (4) above, and is to be plated. A step of immersing the steel wire in a bath of molten metal, a step of pulling the steel wire to be plated out of the bath, and a step of cooling the steel wire to be plated are provided. After the surface temperature of the plating layer formed on the surface of the wire falls below the solidification completion temperature, injection of the refrigerant onto the steel wire to be plated is started, and in the cooling, the plating layer of the steel wire to be plated After the surface temperature falls below 280 ° C., the injection of the refrigerant onto the steel wire to be plated is completed, and in the cooling, the average cooling rate of the surface of the plating layer of the steel wire to be plated is adjusted to the injection of the refrigerant. In the temperature range from the surface temperature of the plating layer to 280 ° C. at the start of the above, the temperature is 50 to 150 ° C./s.

The hot-dip plated steel wire of the present invention does not crack or peel in the plating layer even if it is wound or drawn after the plating film treatment, high corrosion resistance is obtained, and strength and ductility do not decrease. It is a hot-dip plated steel wire with excellent workability and corrosion resistance that can be applied to products, and its industrial contribution is extremely remarkable.

It is a manufacturing process drawing of the hot-dip plated steel wire which concerns on embodiment of this invention.

In order to solve the above problems, the present inventor has made a melt plating component consisting of Mg: 0.10 to 1.00%, Al: 5.0 to 15.0%, and the rest of Zn and impurities in mass%. , The effect of the structure of the plating layer on workability and corrosion resistance was investigated diligently. As a result, the present inventors have found that the cracking of the plating layer is strongly influenced by the phase containing 90% or more of Zn, and the cracking of the plating layer can be reduced by appropriately controlling the crystal size of this phase.
The present inventors have also found that by suppressing cracking of the plating layer, it is possible to suppress a decrease in strength and ductility of the hot-dip plated steel wire.
Furthermore, the present inventors have found that since the present plating component contains Mg, higher corrosion resistance can be obtained as compared with hot-dip plated steel wire made of Zn—Al or Zn, and completed the present invention.

Further, when the hot-dip plating component optionally contains Si in addition to Zn, Al, and Mg, the formation of FeAl intermetallic compounds at the interface between the base iron and the plating can be suppressed, and the workability can be further improved. Found. In addition, an element selected from the group consisting of Fe, Sb, Pb, Sn, Ca, Co, Mn, P, B, Bi, Cr, REM, Ni, Ti, Zr, and Sr can be used alone or optionally. It was found that the processability and corrosion resistance of the hot-dip plated steel wire were further improved by adding them to the hot-dip plating component in a complex manner.

In the solidified structure of the plated layer containing less than 0.10 to 1.00% of Mg in the hot-dip plated steel wire according to the present embodiment, a phase having a high Al concentration is generated as a primary crystal at the beginning of solidification, and then Zn is generated. A phase containing 90% or more (hereinafter referred to as Zn phase) and an MgZn phase are formed.
At this time, the hard MgZn phase is distributed and precipitated at the grain boundaries of the Zn phase and the Al primary crystal. The MgZn phase maintains the sacrificial anticorrosion action of the Zn phase and forms a stable protective film, thereby improving the corrosion resistance of the hot-dip plated steel wire. Therefore, it is effective to improve the corrosion resistance of the hot-dip plated steel wire that the MgZn phase is finely and uniformly distributed.

In addition, in order to investigate the cracking behavior of the plated layer, the state of crack generation when strain was introduced by bending the plated steel wire to a diameter four times the wire diameter was observed in detail. As a result, it was clarified that the cracks mainly propagate from the surface layer to the grain boundaries of the Zn phase, but when the Zn phase is coarse, the cracks may propagate through the inside of the Zn phase grains. .. Further, when the crystal grains of the Zn phase are small, it is clear that even when cracks grow at the grain boundaries of the Zn phase, cracks are apparently generated linearly and reach the surface of the steel wire to be plated. Became. In this case, the notch effect may cause a decrease in breaking strength and a decrease in ductility. Further, when the cracks generated in the plating layer are connected at the ground iron interface, the plating layer may be peeled off.

In the hot-dip plated steel wire according to the present embodiment, in order to suppress cracking and peeling of the plating layer during processing and to secure processability and corrosion resistance, the presence of the Zn phase and the distribution of its crystal grain size are appropriate. It is important to control it. In order to properly control the crystal grain size of the plating layer, it is important to control the cooling start temperature and the cooling rate.

Hereinafter, embodiments of the present invention will be described.

Steel wire to be plated The hot-dip plated steel wire according to the present embodiment has a steel wire to be plated and a predetermined plating layer arranged on the surface thereof. The component of the steel wire to be plated is not particularly limited, and may be, for example, a component of a mild steel wire of JIS G 3505: 2017, a hard steel wire of JIS G 3506: 2017, and a piano wire of JIS G 3502: 2013. The melt-plated steel wire according to the present embodiment is obtained by, for example, using a hot-rolled material having such a component as a material, appropriately cold-working the hot-rolled material, and then forming a melt-plated layer on the surface thereof. It is a plated steel wire.

Component of plating layer Below, the unit "%" in the component of the plating layer is "mass%".

Mg: 0.10% or more and less than 1.00% Mg has the effect of stabilizing corrosion products and suppressing the progress of corrosion. In order to obtain this corrosion suppressing effect, Mg of 0.10% or more is required as a plating component. On the other hand, when the plating component contains Mg of 1.00% or more, a large amount of hard ZnMg intermetallic compound is generated, the plating layer becomes hard, and cracks are likely to occur in the processing process of the hot-dip plated steel wire, and locally. Plating peeling may occur and workability may decrease. Therefore, it is preferable to set less than 1.00% as the upper limit of the amount of Mg in the plating component. The amount of Mg in the plating component may be 0.30% or more, 0.40% or more, 0.50% or more, 0.60% or more, 0.70% or more, or 0.80% or more. Further, the amount of Mg in the plating component may be 0.80% or less, 0.70% or less, 0.60% or less, 0.50% or less, 0.40% or less, or 0.30% or less.

Al: 5.0% or more and 15.0% or less Al also has the effect of stabilizing corrosion products in the same manner as Mg. If the amount of Al in the plating component is less than 5.0%, the effect becomes small and it becomes difficult to obtain the effect of improving corrosion resistance. On the other hand, when the amount of Al in the plating component exceeds 15.0%, the effect is saturated, the melting point of the plating bath becomes high, and surface oxidation easily proceeds. Therefore, the amount of Al in the plating component is preferably 15.0% or less. The amount of Al in the plating component is 7.0% or more, 7.5% or more, 8.0% or more, 9.0% or more, 10.0% or more, 11.0% or more, or 12.0% or more. May be. The amount of Al in the plating component is 12.0% or less, 11.0% or less, 10.0% or less, 9.0% or less, 8.0% or less, 7.5% or less, or 7.0% or less. May be.

Si: 0% or more and 2.0% or less Since Si does not have to be contained in the plating layer, the lower limit of the Si content in the plating component is 0%. On the other hand, Si contained in the plating layer is an element effective for improving corrosion resistance by forming _{Mg 2 Si in the plating layer.} Further, Si has an effect of suppressing the reaction between Fe and Al at the interface of the base iron, suppressing the formation of an intermetallic compound mainly composed of Fe and Al, and improving the workability of the plated steel wire. However, when the amount of Si in the plating component exceeds 2.0%, the effect is saturated and it is disadvantageous in terms of cost. Therefore, the Si content in the plating component was set to 2.0% or less. In order to surely obtain the above effect, it is preferable that the content of Si in the plating component is 0.01% or more, 0.05% or more, or 0.10% or more. Further, the content of Si in the plating component may be 1.00% or less, 0.90% or less, or 0.85% or less.

Fe: 0% or more and 1.0% or less, Sb: 0% or more and 1.0% or less, Pb: 0% or more and 1.0% or less, Ca: 0% or more and 1.0% or less, Co: 0% or more 1 From 0.0% or less, P: 0% or more and 1.0% or less, B: 0% or more and 1.0% or less, Bi: 0% or more and 1.0% or less, and REM: 0% or more and 1.0% or less. Since it is not necessary to contain Fe, Sb, Pb, Ca, Co, P, B, Bi, and REM in one or more types of plating layers selected from the above group, the content of these elements in the plating component. The lower limit of is 0%. On the other hand, when one or more of these elements are contained in the plating layer, the corrosion resistance of the plating layer is further improved. However, even if each of these elements exceeding 1.0% is contained in the plating layer, the effect is saturated and the processability is further lowered, which is disadvantageous in terms of cost. Therefore, the upper limit of the content when these arbitrary elements are contained is set as described above. In order to surely obtain the above effect, it is desirable that the content of each element is 0.01% or more.

Selected from the group consisting of Sr: 0% or more and 1.0% or less, Cr: 0% or more and 1.0% or less, Mn: 0% or more and 1.0% or less, and Sn: 0% or more and 1.0% or less. Since it is not necessary to contain Sr, Cr, Mn, and Sn in one or more types of plating layers, the lower limit of the content of these in the plating component is 0%. On the other hand, when one or more of these elements are contained in the plating layer, improvement in corrosion resistance of the plating layer and improvement in processability of the plating layer can be expected. However, if it exceeds 1.0%, segregation of these components becomes large and cracks may easily occur during processing. Therefore, the upper limit is set to 1.0%. In order to surely obtain the above effect, it is preferable that the content of each element is 0.01% or more.

Mo: 0% or more and 1.0% or less Since Mo does not have to be contained in the plating layer, the lower limit of the Mo content in the plating component is 0%. On the other hand, when Mo is contained in the plating layer, improvement in corrosion resistance of the plating layer and improvement in wear resistance of the plating layer can be expected. However, if it exceeds 1.0%, the plating layer may become hard and the workability may decrease. Therefore, the upper limit is set to 1.0%. In order to surely obtain the above effect, the Mo content is preferably 0.01% or more.

Selected from the group consisting of Ni: 0% or more and 1.0% or less, Ti: 0% or more and 1.0% or less, Zr: 0% or more and 1.0% or less, Sr: 0% or more and 1.0% or less 1 Since it is not necessary to contain Ni, Ti, Zr, and Sr in the seed or two or more kinds of plating layers, the lower limit of the content of these elements in the plating component is 0%. On the other hand, when these elements are contained in the plating layer, all of these elements have the effect of crystallizing an intermetallic compound with Al and improving the surface smoothness of the hot-dip plated steel wire. However, if these elements are contained in the plating layer in an amount of more than 1.0%, on the contrary, the plating surface becomes rough and poor appearance occurs. Therefore, the upper limit of the content when these arbitrary elements are contained is set to 1.0% or less. In order to surely obtain the above effect, it is preferable that the content of each element is 0.01% or more.

Remaining components of the plating layer: In the components of the plating layer containing Zn and impurities, Mg, Al, and optional elements Si, Fe, Sb, Pb, Sn, Ca, Co, Mo, Mn, P, B, Except for Bi, Cr, REM, Ni, Ti, Zr, and Sr, the balance contains Zn and impurities. Impurities are components that are mixed in by various factors in the molten metal raw material or the manufacturing process when the plating layer is industrially manufactured, and are within a range that does not adversely affect the hot-dip plated steel wire according to the present embodiment. Means what is acceptable.

The components of the plating layer can be specified by the following means. The C cross section of the plated steel wire (cross section perpendicular to the longitudinal direction of the plated steel wire) is polished, and the region of the plating layer portion on the polished surface is quantitatively analyzed by EPMA (Electron probe Micro Analyzer). When an alloy layer is formed at the ground iron interface, the plating layer portion that does not include the alloy layer is analyzed in the quantitative analysis. The average value obtained by carrying out this measurement at three locations is regarded as a component of the plating layer of the plated steel wire.

Structure of plating layer Abundance ratio of phase (Zn phase) containing 90% or more of Zn in mass% Mg: 0.1% or more and less than 1.0%, and Al: 5.0% or more and 15.0% or less In the structure of the layer, first crystals containing Al are first formed at the initial stage of solidification, solidification of the plating layer progresses as the temperature of the plating layer decreases, and then from the Zn-based phase (Zn phase) and ZnMg. A eutectic structure (ZnMg phase) is formed.

The Zn phase at this time has a Zn concentration of at least 90% or more. Since the Zn phase is a soft phase, if the abundance ratio of the Zn phase is less than 25% in terms of the area ratio of the plating layer to the entire structure, the plating layer becomes hard and the workability of the hot-dip plated steel wire deteriorates. On the other hand, when the abundance ratio of the Zn phase exceeds 70% in terms of the area ratio of the plating layer to the entire structure, the Zn phase becomes excessive, the corrosion resistance is equivalent to that of Zn plating, and the effect of improving the corrosion resistance cannot be obtained. Therefore, the abundance ratio of the Zn phase is 25 to 70% in terms of the area ratio of the plating layer to the entire structure. More preferably, the area ratio of the Zn phase is 30% or more, 35% or more, or 40% or more. More preferably, the area ratio of the Zn phase is 80% or less, 70% or less, 60% or less, or 50%.

Absence ratio of Zn phase having a predetermined particle size The crystal grain size of the Zn phase, which is a phase containing 90% or more of Zn in mass%, changes depending on the cooling rate of the plating layer in the manufacturing stage of the hot-dip plated steel wire and is distributed in a certain range. have. When the cooling rate is high, the Zn phase has a fine crystal grain size, and when the cooling rate is slow, the Zn phase has a coarse crystal grain size.

If the hot-dip plated steel wire is processed so as to introduce strain, cracks may occur in the plated layer. When the cracks generated in the plating layer reach the interface (base iron interface) between the plating layer and the base iron (steel wire to be plated), they propagate in the base iron, and the notch effect reduces the strength and ductility of the steel material. May cause. Further, when cracks grow to the interface of the base iron and are connected, peeling of the plating layer may occur locally. In this case, since the base iron is exposed at the peeled portion of the plating layer, the corrosion resistance is lowered. Therefore, it is required that the plating layer does not generate cracks or peel off even if it is processed to introduce strain.

The occurrence and progress of cracks when strain acts on the plating layer greatly differ depending on the morphology and particle size of the Zn phase. When the particle size of the Zn phase is large, cracks grow in the grains of the Zn phase, and cracks with large openings are generated on the surface of the plating layer. On the other hand, when the Zn phase is fine, cracks may occur along the grain boundaries of the Zn phase, and the cracks may not penetrate the plating layer and remain as fine cracks. However, in the case of a finer Zn phase structure, although cracks grow at the grain boundaries, the cracks grow almost linearly, and the cracks grow to the ground iron (steel wire to be plated), which is corrosion resistant. May lead to reduced and reduced ductility. Therefore, in order to suppress the occurrence of cracks, it is necessary to appropriately control the crystal particle size of the Zn phase, the minimum particle size of which is 2 μm, and the maximum particle size of which is 5 μm. That is, it is necessary for the hot-dip plated steel wire according to the present embodiment to increase the amount of the Zn phase having a crystal particle size of 2 to 5 μm in terms of yen as much as possible.

However, all the Zn phase crystal grains do not necessarily have a crystal grain size of 2 to 5 μm. In order to suppress the growth of cracks and ensure corrosion resistance, it is preferable that the Zn phase having a crystal particle size of 2 to 5 μm is 20 area% or more of the total Zn phases. It is preferable that the area ratio of the Zn phase having a particle size of 2 to 5 μm in terms of yen among all the Zn phases is large, and the upper limit thereof is 100%. The area ratio of the Zn phase having a particle size of 2 to 5 μm in terms of yen among all the Zn phases may be defined as 30% or more, 40% or more, or 45% or more. The area ratio of the Zn phase having a particle size of 2 to 5 μm in terms of yen among all the Zn phases may be defined as 95% or less, 90% or less, or 80% or less.

In the case of a fine structure, the decrease in ductility may be suppressed because the cracks become finer, but in a corroded environment, many cells of the local battery are formed, the reaction interface increases, and the plating layer is corroded. It will be easier to proceed. Therefore, the lower limit of the crystal particle size of the Zn phase, which is more preferable, is 2.5 μm. Further, a more preferable upper limit of the particle size for suppressing the crack growth of the Zn phase is 4.5 μm. After satisfying the above requirements, it is more preferable that the abundance ratio of the Zn phase having a crystal particle size of 2.5 to 4.5 μm converted into yen is 30 to 100%.

The plating layer structure is quantified by the following procedure. First, the C cross section (cross section perpendicular to the longitudinal direction of the hot-dip plated steel wire) of the plating layer is observed with a backscattered electron image of a scanning electron microscope (SEM) to specify the plating layer region. As will be described later, the hot-dip plated steel wire according to the present embodiment may be provided with an alloy layer, a base plating layer, or the like between the base iron and the plating layer, but in quantifying the plating layer structure, These alloy layers, base plating layers, etc. are excluded from the analysis. In the case of the backscattered electron image, the base iron, the alloy layer, and other layers such as the plating layer and the base plating layer can be easily distinguished. Next, the distribution of the components of the plating layer is analyzed with an energy dispersive X-ray spectrometer (EDS: Energy dispersive X-ray spectrometer) (so-called surface analysis). The phase having a Zn concentration of 90% identified by this is determined to be the Zn phase. Then, the area of all Zn phases confirmed in the cross section of the plating layer is divided by the area of the cross section of the plating layer to obtain the abundance ratio of the Zn phase in the cross section to be measured. This procedure is repeated in three cross sections, and the average value of the abundance ratio of the Zn phase in the three cross sections obtained by this is taken as the area ratio of the Zn phase in the hot-dip plated steel wire.
In addition, the cross section is analyzed by electron backscatter diffraction (EBSD), and the large-angle grain boundaries with a crystal orientation angle difference of 15 degrees or more are regarded as crystal grain boundaries, and the analysis results are analyzed by EBSD analysis software. By the analysis, the particle size distribution of the crystal grains constituting the plating layer can be obtained. By combining with the analysis data of EDS when determining the crystal particle size of the Zn phase by EBSD, the distribution of the crystal particle size can be obtained only in the region where the Zn concentration is 90% or more. By integrating the area ratio of the Zn phase having a crystal particle size of 2 to 5 μm and calculating the ratio of the Zn phase having a crystal particle size of 2 to 5 μm to the area of all Zn phases, the appropriate grain in the cross section to be analyzed The abundance ratio of the Zn phase having a diameter can be obtained. This procedure is repeated in three cross sections, and the average value of the abundance ratio of Zn phases having an appropriate particle size in the three cross sections obtained is taken as the abundance ratio of Zn phases having an appropriate particle size in the hot-dip plated steel wire.

In molten plated steel wire according to the present embodiment, the coating weight is not necessarily limited is not the sole, for example from 50 g / m ² approximately thin plating to 300 g / m ² or more thick plating, broad numerical range depending on the application Can be selected. By optimizing the composition and structure of the plating layer as described above, the workability and corrosion resistance of the hot-dip plated steel wire can be ensured regardless of the amount of plating adhesion.
The amount of plating adhered is measured according to JIS G 3548: 2011 "galvanized steel wire". The specific procedure is as follows. 3.5 g of hexamethylenetetramine is dissolved in 500 ml of hydrochloric acid having a mass fraction of 35%, and a hot-dip plated steel wire cut to a length of 300 mm to 600 mm is immersed in a solution obtained by diluting the solution to 1 L until no bubbles are generated. To do. Weight of hot-dip plated steel wire before immersion (that is, mass before removing the plating film of the test piece) W ₁ (g), and weight of the steel wire after melting the plating layer (that is, removing the plating film of the test piece) W ₂ (g) and the wire diameter d (mm) of the steel wire after the plating layer is melted are measured. By substituting these numerical values into the following formula, the plating adhesion amount A (g / m ² ) can be obtained.
A = ((W ₁ − W ₂ ) / W ₂ ) × d × 1960

Similarly, the thickness of the plating layer of the hot-dip plated steel wire according to the present embodiment is not particularly limited. For example, the thickness of the plating layer may be in the range of 7 to 55 μm. For the thickness of the plating layer, SEM observe the plating layer on the C cross section, measure the thickness of the plating layer part including the alloy layer at 8 points around the circumference including the maximum plating thickness and the minimum plating thickness. It can be calculated as the average value of 8 points.

Manufacturing Method Next, a method of manufacturing the hot-dip plated steel wire according to the present embodiment will be described. The method for manufacturing a hot-dip plated steel wire according to the present embodiment includes a step of immersing the steel wire to be plated in a bath of molten metal, a step of pulling the steel wire to be plated out of the bath, and a step of cooling the steel wire to be plated. And. The method for manufacturing the steel wire to be plated is not particularly limited.

An example of the manufacturing process of the hot-dip plated steel wire is shown in FIG. The scale (iron oxide) generated on the surface of the hot-rolled wire is pickled or mechanically removed, and after the surface of the hot-rolled wire is coated, the hot-rolled wire is cooled by drawing with a die or roll. A wire (steel wire 1 to be plated) is obtained by adjusting the wire diameter to the target wire diameter by interprocessing. After arbitrarily heat-treating the steel wire 1 to be plated, degreasing, pickling, and primary plating by electroZn plating or hot-dip galvanizing are performed by the plating pretreatment device 2. Next, the primary-plated steel wire 1 to be plated is immersed in a bath in which the plating metal as a component of the plating layer for producing the hot-dip plated steel wire according to the present embodiment is melted, and the molten metal is placed on the surface of the steel wire 1 to be plated. Form the coating of 3. After the steel wire 1 to be plated is pulled out of the bath, the molten metal is cooled and solidified to form a plating layer.

The primary plating and hot-dip plating may be carried out by continuously passing and dipping the steel wire 1 to be plated. On the other hand, after the steel wire 1 to be plated after the primary plating is once wound, the steel wire 1 to be plated may be immersed again in the plating bath in the manufacturing method according to the present embodiment.

The structure of the plating layer is controlled by controlling the conditions of forced cooling performed in the secondary cooling device 5 after the steel wire 1 to be plated is pulled up from the molten metal bath and allowed to cool in the primary cooling device 4. This makes it possible. Specifically, the cooling start temperature and the average cooling rate in the secondary cooling device 5 are important for controlling the structure of the plating layer. Here, the cooling start temperature in the secondary cooling device 5 means the surface temperature of the steel wire 1 to be plated when the secondary cooling device 5 starts injecting the refrigerant into the steel wire 1 to be plated. The refrigerant is, for example, water, gas, mist, etc., but is not limited thereto.

The cooling is cooling before the plating layer in the secondary cooling device 5 is forcibly cooled, and the temperature difference between the steel wire 1 to be plated and the ambient temperature of the primary cooling device 4 can be obtained without spraying the refrigerant. It means to cool the steel wire 1 to be plated by using it. The average cooling rate in this cooling is the surface temperature (molten metal temperature) of the steel wire 1 to be plated when the steel wire 1 to be plated is pulled up from the bath of molten metal, and the steel wire 1 to be plated in the secondary cooling device 5. The difference from the surface temperature of the steel wire 1 to be plated until the injection of the refrigerant is started until the steel wire 1 to be plated is pulled up from the molten metal bath until the injection of the refrigerant to the steel wire 1 to be plated is started. It is the value divided by the time of. In the cooling process, it is preferable that the cooling is performed at a cooling rate having an average cooling rate of less than 50 ° C./s.

Forced cooling start temperature The forced cooling start temperature is important to control the structure of the plating layer. The solidification completion temperature is a temperature at which the plating layers are all solid-phase. When the temperature of the plating layer is between the solidification start temperature and the solidification completion temperature, the plating layer is in a solid-liquid mixed state.

When the steel wire 1 to be plated is forcibly cooled from a temperature higher than the solidification completion temperature of the plating layer, the unsolidified layer of the plating layer is disturbed by the injection of the refrigerant, and the surface texture of the plating layer is deteriorated. Therefore, it is preferable to start forced cooling after the surface temperature of the plating layer is lower than the solidification completion temperature and the temperature reaches a temperature at which no liquid phase exists.

On the other hand, even if forced cooling is started after the temperature of the plating layer has dropped to a low temperature, solidification of the plating layer progresses slowly, and the structure cannot be controlled. Therefore, the lower limit of the forced cooling start temperature is preferably 300 ° C. Here, the solidification completion temperature of the plating layer described above is the temperature at which the liquid phase disappears in the equilibrium state, and the value of the equilibrium state obtained from the components of the molten metal by Thermo-Calc of the integrated thermodynamic calculation software. Is. The end temperature of forced cooling is preferably 280 ° C. or lower, which is the eutectoid transformation temperature of Zn and Al. This is because the crystal grain size of the Zn phase hardly changes at 280 ° C. or lower.

Forced cooling rate In order to preferably control the structure of the plating layer of the hot-dip plated steel wire according to the present embodiment, it is necessary to cool the plating layer at a sufficiently high forced cooling rate. If the average cooling rate of the plating layer is less than 50 ° C./s, the structure miniaturization effect is small, the structure of the plating layer grows and becomes coarse, and a preferable Zn phase particle size distribution cannot be obtained. On the other hand, even if forced cooling is performed at an average cooling rate of more than 150 ° C./s, the controllability of the structure is saturated, solidification cracks occur in the plating layer, and workability is deteriorated. Therefore, in the manufacturing method according to the present embodiment, the average cooling rate in forced cooling is set to 50 ° C./sec to 150 ° C./sec in the temperature range from the surface temperature of the plating layer at the start of the injection of the refrigerant to 280 ° C. Control. More preferably, it is 70 ° C./sec to 130 ° C./sec. In the forced cooling in the secondary cooling device 5, the average cooling rate is the difference between the above-mentioned cooling start temperature and 280 ° C., which is the time from the start of the refrigerant injection until the surface temperature of the plating layer reaches 280 ° C. It is the divided value. If the refrigerant injection ends before the surface temperature of the plating layer reaches 280 ° C., the average cooling rate determines the difference between the cooling start temperature and the surface temperature of the plating layer at the end of the refrigerant injection from the start of the refrigerant injection to the end. It is considered to be the value divided by the time until.

The average cooling rate in forced cooling can be adjusted by the cooling method, and in the water cooling method, it can be controlled by adjusting the amount of cooling water, the cooling time, and the like. Further, the average cooling rate in forced cooling may be controlled by a method using a nozzle of two fluids, air or water, a water film or the like as a cooling nozzle, or by injecting a specific gas. However, in the manufacturing method according to the present embodiment, the forced cooling method is not limited to the above method, and any cooling method can be applied.

As described above, by controlling the components and structure of the plating layer of the hot-dip plated steel wire to the components and structure of the plating layer of the present embodiment described above, cracks occur in the plating layer even when various processes are performed. It is possible to obtain a hot-dip plated steel wire having good workability and corrosion resistance, which does not cause peeling or peeling, has better corrosion resistance as compared with Zn plating or Zn-Al plating, and does not reduce strength and ductility.

Further, the characteristics such as the steel composition and strength of the steel wire to be plated are not particularly limited. For example, a steel material containing C: 0.01 to 1.2%, Si: 0.01 to 1.5%, Mn: 0.01 to 2.0%, and the balance containing iron and impurities, the above-mentioned alloying elements. In addition to this, a steel material containing 0.5% or less of Cr, a steel material further containing Ti, B, Al, Cu, Mo, Sn, etc. in addition to the above-mentioned alloying elements, etc. Can be a steel wire to be plated. Further, the surface of the steel wire to be plated may be subjected to electric Zn plating, hot-dip galvanizing, and hot-dip zinc alloy plating (for example, Zn alloy to which Al and Mg are added). That is, the hot-dip plated steel wire according to the present embodiment may further have the above-mentioned base plating layer between the plating layer having the above-mentioned components and the steel wire to be plated. Further, an alloy layer containing Fe-Al-Zn-Mg as a main component having a thickness of 1 μm or more may be formed at the interface between the base iron which is the steel wire to be plated and the plating layer. When a base plating layer, an alloy layer, etc. are formed between the plating layer and the steel wire to be plated, when identifying the chemical composition and structure of the plating layer, as described above, the measurement area is other than the plating layer. Must not include the area. The wire diameter of the hot-dip plated steel wire is also not particularly limited, and may be, for example, 2.0 mm to 5.0 mm.

Hereinafter, examples of the present invention will be described. The present invention is not necessarily limited to the method described in this example.

Table 1 shows the components of the steel material of the hot-rolled wire rod having a wire diameter of 5.5 mm (the rest of the described components are Fe and impurities). Dry wire drawing was carried out on this hot-rolled wire. The hot-rolled wire rod was previously pickled to remove scale and then treated with a zinc phosphate coating. Then, using a dry lubricant mainly composed of calcium stearate, the hot-rolled wire was drawn until the wire diameter became 2.51 mm under the condition that the 1-pass surface reduction rate was 16 to 24%.

Next, the steel wire to be plated was subjected to base plating (primary plating) and then hot-dip plating. The primary plating was either electroplating or hot dip galvanizing.
The manufacturing method when the primary plating is electroplating is as follows. After degreasing the above-mentioned wire drawing material with an alkaline solution to remove the wire drawing lubricant, the steel materials A and B are not heat-treated, and the steel material C is heat-treated and pickled, and then an electric Zn having a thickness of 1 to 2 μm is obtained. Plating was carried out, followed by immersion in molten metal containing Zn, Al, Mg and, if necessary, optional additive elements, and vertically pulled up from the bath to produce hot-dip plated steel wire. Table 2-1 shows the bath components and the types of base plating. In the hot-dip plated steel wire produced by this process, a thick alloy layer containing Fe-Al-Zn (Mg) is not formed at the interface between the base iron and the plating layer. The rest of the bath components shown in Table 2-1 are Zn and impurities. In the production of Comparative Examples 27 to 29, a so-called pure Zn plating bath was used.
When the primary plating is hot-dip galvanizing, the wire drawing material is degreased with an alkaline solution to remove the wire drawing lubricant, and then the steel materials A and B are not heat-treated, and the steel material C is heat-treated and pickled. After that, it is immersed in a bath in which Zn is melted to form a hot-dip galvanized layer on the surface, and then wound up once or continuously, or immersed in a molten metal containing Zn, Al, Mg and, if necessary, an optional additive element. , The plated wire was manufactured by pulling it vertically from the bath. The hot-dip plated wire produced by this process has an alloy layer containing Fe-Al-Zn-Mg as a main component having a thickness of 1 μm or more formed at the interface between the base iron and the plating layer. When the primary plating is electroplating, an alloy layer is not formed at the interface between the base iron and the hot-dip plating, and when the primary plating is hot-dip galvanizing, an alloy layer is formed at the interface between the base iron and the hot-dip plating. Become.

By changing the Al and Mg concentrations of the molten metal at this time, the cooling start temperature after pulling up from the bath, and the cooling rate, molten-plated steel wires having different components and structures of the plating layer were produced. The amount of plating adhered was adjusted to 300 to 350 g / m ^2. In all the invention examples and comparative examples, forced cooling by spraying the refrigerant was carried out up to 280 ° C. or lower. Table 2-2 shows the cooling start temperature, which is the refrigerant spraying temperature, and the average cooling rate from the start of cooling to 280 ° C. Table 2-2 also shows the solidification completion temperature calculated from the chemical composition of the molten metal by Thermo-Calc, an integrated thermodynamic calculation software.

The winding workability of the hot-dip plated steel wire was evaluated by the following method. The hot-dip plated steel wire was wound around the outer circumference of the steel wire having an outer diameter four times the diameter of the hot-dip plated steel wire six times, and the crack generation state of the wound hot-dip plated steel wire was investigated by observing the appearance and cross section. When no crack was confirmed on the surface of the plating layer and the cross section of the plating layer, it was judged that the winding workability of the hot-dip plated steel wire was extremely good (VERY GOOD), and it was described as "VG" in the table. Although there are no cracks on the surface of the plating layer, if cracks are observed in the cross-sectional observation and this stops in the plating layer and does not extend to the ground iron interface, it is judged that the winding workability is good (GOOD), and "G" is shown in the table. It was described. When a crack propagated from the surface of the plating layer to the interface of the base iron, it was judged that the winding workability was poor (BAD), and it was described as "B" in the table.

Corrosion resistance evaluation of hot-dip plated steel wire was carried out by the following method. The salt spray test described in JIS Z 2371: 2015 "Salt spray test method" was carried out on the hot-dip plated steel wire which was not stranded. The corrosion resistance of the hot-dip plated steel wire was evaluated by the corrosion weight reduction of the hot-dip plated steel wire after spraying with salt water for 1000 hours. An index was obtained with the corrosion weight loss of a normal Zn-plated steel wire (Zn-plated steel wire of Comparative Example 27) as 100, and when the corrosion weight loss was 25% or less of that of Zn plating, it was judged that the corrosion resistance was extremely good. Further, when the corrosion weight loss was 25 to 40% of that of Zn plating, it was judged that the corrosion resistance was good. When the corrosion weight loss was more than 40% of the Zn plating, it was judged that the corrosion resistance improving effect was small and the corrosion resistance was poor.

As comparative materials, pure Zn-plated steel wire, Zn-5% Al-plated steel wire, and Zn-10% Al-plated steel wire were also manufactured in the same manner and their characteristics were evaluated.

The wire drawing workability evaluation of the hot-dip plated steel wire was carried out by the following method. A plated steel wire obtained by melt-plating a steel wire to be plated having been drawn to 2.51 mm was drawn using a die in a range of 1-pass surface reduction rate of 15 to 20%. Grasp and twist the hot-dip plated steel wire after wire drawing at a different chuck distance for each wire drawing diameter (specifically, the chuck distance that is 100 times the wire diameter of the wire drawing material). The test was conducted. In the torsion test, the wire drawing strain ε was obtained from the wire diameter at the limit where vertical cracking (delamination) occurred. Here, ε is a value obtained by the following equation.
ε = 2 × ln (d0 / d)
d0: Plated steel wire diameter d: Wire diameter after wire drawing With the steel component in Table 1, the limit wire drawing strain (ε) of pure Zn plated material is set to 100, and the limit wire drawing of various plated steel wires with the same steel component. The processing strain was indexed and evaluated as a wire drawing workability index. When the wire drawing workability index was 100 or more, it was judged that the wire drawing workability was extremely good, and it was described as "VG" in the table. When the wire drawing workability index was less than 80 to 100, it was judged that the wire drawing workability was good, and it was described as "G" in the table. When the wire drawing workability index was less than 80, it was judged that the wire drawing workability was poor, and it was described as "B" in the table.

Table 2-3 shows the characteristics evaluation results of the hot-dip plated steel wires of the examples of the present invention and the comparative examples. In Tables 2-1 to 2-3, values outside the scope of the invention and values that do not meet the above pass / fail criteria are underlined. The abundance ratio of the Zn phase in the examples of the present invention and the comparative example and the ratio of the Zn phase having a circle equivalent diameter of 2 to 5 μm to the total Zn phase were determined by the following procedure. First, the C cross section of the plating layer (the cross section perpendicular to the longitudinal direction of the hot-dip plated steel wire) was observed with a scanning electron microscope (SEM), and the components of the solidified structure were analyzed with an energy dispersive X-ray spectrometer (EDS). .. The phase having a Zn concentration of 90% identified by this was determined to be the Zn phase. Then, the abundance ratio of the Zn phase was determined from the area ratio of the Zn phase in the entire cross section. In addition, the cross section is analyzed by electron backscatter diffraction (EBSD), and the large-angle grain boundaries with a crystal orientation angle difference of 15 degrees or more are regarded as crystal grain boundaries, and the analysis results are analyzed by EBSD analysis software. By the analysis, the particle size distribution of the crystal grains constituting the plating layer was obtained. By combining with the analysis data of EDS when determining the crystal particle size of the Zn phase by EBSD, the distribution of the crystal particle size was determined only in the region where the Zn concentration was 90% or more. By integrating the area ratios of Zn phases having a crystal particle size of 2 to 5 μm and calculating the ratio of Zn phases having a crystal particle size of 2 to 5 μm to the area of all Zn phases, the abundance ratio of Zn phases having an appropriate particle size Asked.

No. of the present invention. The hot-dip plated steel wires 1, 6 to 8, 12 to 14, 16, 18, 19, 23, and 26 did not crack in the winding test and had extremely good winding workability. No. In 2-5, 9-11, 15, 17, 20-22, 24, 25, fine cracks were confirmed in the plating layer, but there were no cracks penetrating the plating layer or cracks opened on the surface, and winding was performed. The workability was judged to be good.
When Fe, Zn, and Al alloy layers are formed at the interface between the base iron and the plating layer, cracks may tend to occur in preference to the alloy layer during bending, but in the structure of the present invention, the entire plating layer No cracks penetrated into the surface, and no cracks were observed in appearance.
Regarding the wire drawing workability, the influence of the alloy layer at the interface was not observed, and the hot-dip plated steel wire of the present invention was No. Compared with the same steel components as the pure Zn plating of 27, 28, and 29, good wire drawing workability can be ensured, which is 80% or more of the standard Zn-plated wire.

Further, the corrosion resistance is No. 1 of the comparative material. 27, 28, 29 pure Zn plating materials, No. 30 Zn-10% Al plating and No. Compared with 31 Zn-5% Al, better results were obtained in the example of the present invention. No. of the present invention. In Nos. 7, 12 and 13, the corrosion resistance index was 37, 35, 32 because the amount of Mg was small, and the corrosion resistance was judged to be good.

No. of the plated steel wire of the present invention. In No. 6, since the amount of Mg is high, the wire drawing workability is slightly low, but it is a level judged to be good. In addition, No. 1 manufactured from steel material A. Nos. 16 and 19 to 26 contain arbitrary additive elements other than Si, and the plating layer becomes hard. The wire drawing workability is lower than that of the pure Zn plating of 27, but it is still at a level judged to be good. The wire drawing workability of the other plated steel wire of the present invention is equal to or higher than that of the pure Zn plated steel wire.

Comparative example No. Reference numeral 27 denotes pure Zn plating using the steel material A. No. Reference numeral 28 denotes pure Zn plating using the steel material B. No. Reference numeral 29 denotes pure Zn plating using steel material C. These comparative examples were used as evaluation criteria, and the plating was soft and the workability and wire drawing workability were good. However, in the corrosion resistance test, white rust occurred at an early stage and the corrosion rate was relatively fast. The corrosion resistance standard is described as "100" for use as a comparison standard. The wire drawing workability was used as the standard for each steel material.
No. Reference numeral 30 denotes Zn-10% Al plating (which does not contain Mg), which has better corrosion resistance than Zn plating but is inferior to the present invention.
No. No. 31 is also Zn-5% Al-plated (does not contain Mg). The amount of Al was less than 30, and No. This is an example in which corrosion resistance is inferior to 30.
No. 32 is an example in which Mg is below the lower limit of the present invention and the corrosion resistance is inferior.
No. No. 33 contains a large amount of Mg and has good corrosion resistance, but is an example in which the winding workability and the wire drawing workability are inferior because the MgZn intermetallic compound is formed and the plating layer becomes hard.
No. Reference numeral 34 denotes an example in which the amount of Al is below the lower limit of the present invention, the corrosion resistance is inferior, and the plating layer is cracked due to rapid cooling from a temperature higher than the solidification completion temperature, resulting in deterioration in both winding workability and wire drawing workability.
No. Reference numeral 35 denotes an example in which the amount of Al is large, the Zn phase is small, the plating layer is hard, and the winding workability and wire drawing workability are deteriorated.
No. No. 36 is an example in which the plating component is within the range of the present invention, but the cooling rate under the manufacturing conditions is as slow as 12 ° C./s, so that the Zn phase becomes coarse and large, the corrosion resistance deteriorates, and cracks occur in the winding test. is there.
No. No. 37 was obtained by quenching before falling below the solidification completion temperature. Here, the number of proper crystal grains in the Zn phase was small, and the number of fine grains was large. Therefore, No. No. 37 is an example in which the winding workability is at a passing level, but the corrosion resistance and the wire drawing workability are deteriorated.
No. No. 38 was obtained by slowly cooling at an average rate of 45 ° C./s. Here, there were few crystals having an appropriate particle size of the Zn phase, and there were many coarse particles. Therefore, No. No. 38 is an example in which the corrosion resistance is at a passing level, but the winding workability and the wire drawing workability are deteriorated.
No. Since forced cooling of 39 was started in a state where the solidification of the plating was not completed (semi-molten state), it became a fine solidified structure, the corrosion resistance was lowered and the surface texture was deteriorated, and the winding workability and the wire drawing workability were improved. This is an example of a decrease.
No. No. 40 is an example in which the forced cooling start temperature is less than 280 ° C., that is, the plating layer is allowed to cool and solidify to a low temperature and then forced cooling is started, so that the plating layer structure is coarsened and the winding workability and wire drawing workability are deteriorated. ..
No. No. 41 is an example in which the average cooling rate during forced cooling is as slow as 40 ° C./s, the structure of the plating layer is coarsened, and the winding workability and wire drawing workability are deteriorated.
No. Reference numeral 42 denotes an example in which the average cooling rate during forced cooling was as high as 180 ° C./s, cracks were generated in the plating layer, and the winding workability and wire drawing workability were deteriorated.

The hot-dip plated steel wire of the present invention has good workability and corrosion resistance of the plating layer, and can be applied to various applications, so that it has extremely high industrial applicability.

1 Steel wire to be plated 2 Pretreatment equipment (defatting, pickling, electric Zn plating)
3 Molten metal 4 Primary cooling device 5 Secondary cooling device 6 Hot-dip plated steel wire

Claims (5)

A hot-dip plated steel wire including a steel wire to be plated and a plating layer arranged on the surface of the steel wire to be plated.
The component of the plating layer is mass%,
Mg: 0.10% or more and less than 1.00%,
Al: 5.0% or more and 15.0% or less,
Si: 0% or more and 2.0% or less Fe: 0% or more and 1.0% or less,
Sb: 0% or more and 1.0% or less,
Pb: 0% or more and 1.0% or less,
Sn: 0% or more and 1.0% or less,
Ca: 0% or more and 1.0% or less,
Co: 0% or more and 1.0% or less,
Mo: 0% or more and 1.0% or less,
Mn: 0% or more and 1.0% or less,
P: 0% or more and 1.0% or less,
B: 0% or more and 1.0% or less,
Bi: 0% or more and 1.0% or less,
Cr: 0% or more and 1.0% or less,
REM: 0% or more and 1.0% or less,
Ni: 0% or more and 1.0% or less,
Ti: 0% or more and 1.0% or less,
Zr: 0% or more and 1.0% or less, and Sr: 0% or more and 1.0% or less.
The rest consists of Zn and impurities,
The structure of the plating layer has a Zn phase containing 90% or more of Zn in mass% and 25 to 70% in area ratio.
A hot-dip plated steel wire having a particle size of 2 to 5 μm converted into yen in the Zn phase, wherein the area ratio of the Zn phase is 20 to 100%. When the component of the plating layer is mass%,
The hot-dip plated steel wire according to claim 1, wherein Si: contains 0.01% or more and 2.0% or less. When the component of the plating layer is mass%,
Fe: 0.01% or more and 1.0% or less,
Sb: 0.01% or more and 1.0% or less,
Pb: 0.01% or more and 1.0% or less,
Sn: 0.01% or more and 1.0% or less,
Ca: 0.01% or more and 1.0% or less,
Co: 0.01% or more and 1.0% or less,
Mo: 0.01% or more and 1.0% or less,
Mn: 0.01% or more and 1.0% or less,
P: 0.01% or more and 1.0% or less,
B: 0.01% or more and 1.0% or less,
Bi: 0.01% or more and 1.0% or less,
Claim 1 or claim 1, which contains one or more selected from the group consisting of Cr: 0.01% or more and 1.0% or less, and REM: 0.01% or more and 1.0% or less. 2. The hot-dip plated steel wire according to 2. When the component of the plating layer is mass%,
Ni: 0.01% or more and 1.0% or less,
Ti: 0.01% or more and 1.0% or less,
Claims 1 to 1, which contain one or more selected from the group consisting of Zr: 0.01% or more and 1.0% or less, and Sr: 0.01% or more and 1.0% or less. The hot-dip plated steel wire according to any one of 3. The method for producing a hot-dip plated steel wire according to any one of claims 1 to 4.
The process of immersing the steel wire to be plated in a molten metal bath and
The process of pulling the steel wire to be plated from the bath and
After that, a step of cooling the steel wire to be plated is provided.
In the cooling, after the surface temperature of the plating layer formed on the surface of the steel wire to be plated falls below the solidification completion temperature, the injection of the refrigerant onto the steel wire to be plated is started.
In the cooling, after the surface temperature of the plating layer of the steel wire to be plated falls below 280 ° C., the injection of the refrigerant into the steel wire to be plated is completed.
In the cooling, the average cooling rate of the surface of the plating layer of the steel wire to be plated is 50 to 150 ° C./in the temperature range from the surface temperature of the plating layer to 280 ° C. at the start of injection of the refrigerant. A method for producing a hot-dip plated steel wire, which comprises s.

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