KR101261126B1 - Zn-Al PLATED IRON WIRE AND PRODUCING METHOD THEREFOR - Google Patents

Abstract

This Zn-Al plated iron wire includes an iron wire and a Zn-Al plated layer formed on the surface of the iron wire, wherein the Zn-Al plated layer contains Al in an amount of 3.0% or more and 15.0% or less in mass%. Fractional dimension of the interface between the iron wire and the Zn-Al plated layer, including additional Zn and unavoidable impurities, and limiting Fe in the Zn-Al plated layer to 3.0% or less by mass%, and measured by a box counting method. to be.

Description

Zn-Al-plated iron wire and its manufacturing method {Zn-Al PLATED IRON WIRE AND PRODUCING METHOD THEREFOR}

The present invention relates to a plated iron wire excellent in corrosion resistance and workability and a method for producing the same.

This application claims priority based on Japanese Patent Application No. 2009-154265 for which it applied to Japan on June 29, 2009, and Japanese Patent Application No. 2009-154245 for which it applied to Japan on June 29, 2009. The contents are used here.

Conventionally, hot-dip galvanized iron wire or Zn-Al plated iron wire is applied to other metal net applications other than cage-mats for coastal construction. During the plating of the Zn-Al plated iron wire, Al is added to improve the corrosion resistance of the hot dip galvanized iron wire. When manufacturing a Zn-Al plated iron wire, since non-plating is easy to generate | occur | produce by the oxide layer of the surface of a raw material (iron wire), a two bath method is normally used. In the second bath method, the material is immersed in the hot dip galvanizing bath (first stage zinc plating), and then the material is further immersed in the hot dip Zn-Al plating bath (second stage Zn-Al plating). As described above, the two bath method is a method of producing a Zn-Al plated iron wire by a two-step process.

In the second bath method, a hard Fe-Zn-based alloy generating layer is formed at the interface between the iron wire and the plating by primary hot dip galvanizing, and the Fe-Zn-based alloy generating layer is formed by the secondary Zn-Al plating. To grow. When the thickness of this hard Fe-Zn-based alloy generating layer is increased by the two-stage plating, cracks occur in the Zn-Al plated iron wire during processing. Therefore, although Zn type alloy plating (for example, Zn-Al plating) containing Al is excellent in corrosion resistance compared with pure zinc plating, there exists a problem that fatigue characteristics and workability are inferior.

For this problem, for example, when performing zinc plating and alloy plating (Zn-Al plating) in two steps, a method of limiting the processing time of plating (for example, refer to Patent Documents 1 and 2) or the first step The method (for example, refer patent document 3) of performing zinc plating of electroplating is proposed. However, if the plating treatment time is limited, for example, it becomes difficult to control the composition, structure, and plating deposition amount of the Zn-Al plating layer. In addition, when electroplating, the manufacturing cost of Zn-Al plated iron wire increases.

Therefore, in order to manufacture Zn-Al plated iron wire more flexibly, the method of manufacturing Zn-Al plated iron wire by the one-step plating process is effective. When Zn-Al plating is performed on the steel sheet, the steel sheet is heat-treated in a hydrogen atmosphere without performing primary plating to reduce the surface of the steel sheet, and the steel sheet is immersed in the molten Zn-Al plating bath in one step. However, in order to apply this method to an iron wire, it is necessary to introduce a hydrogen heat treatment facility. In addition, in hot-dip plating of iron wires, a plurality of to-be-plated wires with different wire diameters or steel material components are simultaneously passed through a molten Zn-Al plating bath in consideration of productivity. Therefore, it is also necessary to develop the technology which makes these iron wires stably pass through a molten Zn-Al plating bath.

Therefore, atmospheric heat treatment such as hydrogen heat treatment is not practical considering workability such as line passing when a problem occurs. Therefore, the method of manufacturing a Zn-Al plated iron wire by the one-step plating process using a special flux is proposed (for example, refer patent document 4 and 5).

Japanese Patent Application Publication No. 2002-371343 Japanese Patent Application Publication No. 2003-129205 Japanese Patent Application Publication No. 2003-155549 Japanese Patent Application Laid-open No. Hei 5-156418 Japanese Patent Application Laid-open No. Hei 7-18590

However, even when a Zn-Al plated iron wire is produced by one-step plating treatment using a flux (one bath method), the Fe-Al-based alloy generating layer (Fe-Al) at the interface portion of the base material and the plating layer, depending on the deposition amount of the plating. Due to the intermetallic compound generating layer), cracking or peeling occurs in plating during processing. In addition, in the one bath method, the reaction between the molten metal (melt plating) on the surface of the iron wire and the surface metal of the iron wire tends to be uneven in the circumferential direction and the longitudinal direction of the iron wire. Therefore, in one bath method, it was difficult to form Zn-Al plating stably.

In view of the above circumstances, the present invention provides a Zn-Al plated iron wire excellent in corrosion resistance and workability. Moreover, the manufacturing method of a Zn-Al plated iron wire which forms stable Zn-Al plating on the base material (iron wire) surface by one bath method is provided.

The present inventors analyzed in detail about the cause which the surface property of molten Zn-Al plating iron wires, such as non-plating, deteriorate. As a result, the present inventors have found that the surface properties of Zn-Al plated iron wires are improved by forming irregularities (complex surface, fractal interface) on the surface of the iron wires before plating to increase the stability of the flux treatment. In addition, the present inventors have found that the Zn-Al plated iron wire has a fractal interface at the interface between the base material (iron wire) and the plating layer, so that the adhesion of plating is increased and the workability is improved.

In addition, the present inventors have found that fatigue properties, plating adhesion and corrosion resistance can be improved by appropriately limiting the amount of Al and the amount of Fe in the plating layer. In addition, the present inventors, by the processability of the Zn-Al plated iron wire produced by one bath method is affected by the structure of the plated layer, by suppressing the growth of the Fe-Al-based alloy generating layer generated in the interface between the iron wire and the plated layer It has been found to improve. In addition, the present inventors, on the surface of the Zn-Al plated iron wire, without causing cracking or peeling of the plating due to processing, for example, by optimizing the structure of the plating layer such as Fe-Al-based alloy generating layer and primary crystal. It has been found that irregularities (deformation portions) of an optimized shape can be formed and that slip resistance can be improved.

In addition, the present inventors, when manufacturing a Zn-Al plated iron wire by one bath method, when an appropriate amount of Si is added to the molten Zn-Al plating bath, Fe-Al-based alloy generating layer generated in the interface portion of the iron wire and the plating layer It was found that the growth of (Fe-Al-Si-based alloy generating layer) was suppressed to obtain more uniform plating. In addition, by optimizing the structure of the plating layer such as the Fe-Al-based alloy generating layer, unevenness (deformation part) of an optimized shape on the surface of the Zn-Al plated iron wire without causing cracking or peeling of the plating due to processing. ), It was found that the slip resistance can be improved. This invention is made | formed based on this knowledge, The summary is as follows.

(1) The Zn-Al plating iron wire which concerns on the 1st aspect of this invention contains an iron wire and the Zn-Al plating layer formed in the surface of the said iron wire, The said Zn-Al plating layer is 3.0% or more by mass%, 15.0% or less of Al, the remainder containing Zn and unavoidable impurities, the Fe in the Zn-Al plating layer is limited to 3.0% or less by mass%, and the iron wire and Zn- measured by the box counting method. The fractal dimension of the interface of Al plating layer is 1.05 or more.

(2) In the Zn-Al plating iron wire as described in said (1), the said Zn-Al plating layer may contain Al by 6.0% or more and 15.0% or less by mass%.

(3) In the Zn-Al plating iron wire as described in said (1) or (2), the said Zn-Al plating layer may contain Si of 0.01% or more and 3.0% or less by mass%.

(4) In the Zn-Al plated iron wire according to (1) or (2), the Zn-Al plated layer is a Fe-Al-based alloy between the Zn-Al alloy layer and the iron wire and the Zn-Al alloy layer. A generation layer may be included, and the diameter of the primary crystal of the Zn-Al alloy layer may be limited to 10 μm or less, and the thickness of the Fe—Al alloy generation layer may be limited to 5 μm or less.

(5) In the Zn-Al plated iron wire according to the above (1) or (2), the iron wire is, in mass%, 0.01% or more and 0.70% or less C, 0.1% or more and 1.0% or less Si, It may have a structure containing 0.1% or more and 1.5% or less of Mn, the remainder containing Fe and inevitable impurities, and containing ferrite.

(6) In the Zn-Al plated iron wire according to the above (5), the iron wire further contains at least one element selected from 0.1% or less of Al, 0.1% or less of Ti, and 0.0070% or less of B in mass%. You may also

(7) In the Zn-Al plating iron wire as described in said (1) or (2), the plating adhesion amount of the said Zn-Al plating layer may be 100 g / m <2> or more and 400 g / m <2> or less.

(8) In the Zn-Al plated iron wire according to (1) or (2), recesses are formed on the surface of the Zn-Al plated layer at a density of 2 or more and 100 or less per 1 cm 2 surface area. The part may have a ratio of the depth to the width of 0.2 mm or more and 0.5 mm or less and the width of 0.1 or more and 3 or less.

(9) In the method for producing a Zn-Al plated iron wire according to one embodiment of the present invention, the wire is pickled after being wired and pickled, and the surface of the iron wire measured by the box counting method has a surface dimension of 1.05 or more. An adjustment process is performed, it is made to pass in a flux, and after drying, it immerses in a molten Zn-Al bath containing 3.0% or more and 15.0% or less of Al by mass%, and raises it by water cooling within 3 second.

(10) In the manufacturing method of the Zn-Al plated iron wire as described in said (9), the said molten Zn-Al bath may contain 6.0% or more and 15.0% or less of Al by mass%.

(11) In the manufacturing method of the Zn-Al plating iron wire as described in said (9) or (10), the said molten Zn-Al bath may contain Si of 0.01% or more and 3.0% or less by mass%.

(12) In the method for producing a Zn-Al plated iron wire according to the above (9) or (10), the iron wire is 0.01% or more, 0.70% or less C, 0.1% or more and 1.0% or less in mass%. Si and 0.1% or more and 1.5% or less of Mn may be contained, and the remainder may contain Fe and inevitable impurities, and may have a structure containing ferrite.

(13) In the method for producing a Zn-Al plated iron wire according to the above (9) or (10), after the iron wire is immersed in a molten Zn-Al bath and pulled up, and before water cooling, the plating adhesion amount is 100 g / m 2 or more. The plating deposition amount may be adjusted to be 400 g / m 2 or less.

(14) In the manufacturing method of the Zn-Al plating iron wire as described in said (9) or (10), after water cooling, you may form a recessed part in the surface of a Zn-Al plating layer by laser processing or cold working.

(15) In the method for producing a Zn-Al plated iron wire according to the above (14), the concave portion has a depth of 0.2 mm or more and 0.5 mm or less and a ratio of the depth to the width of 0.1 or more and 3 or less, and the Zn It may be formed at a density of 2 or more and 100 or less per 1 cm 2 of the -Al plating layer.

According to the present invention, the corrosion resistance, workability and slip resistance of the Zn-Al plated iron wire can be improved. Moreover, according to this invention, when using Zn-Al plated iron wire as a raw material of a metal net, the durability and lifetime of a metal net are improved significantly and more complex processing is attained. In particular, in this case, the slip resistance is improved by forming the unevenness (deformation part) on the surface of the Zn-Al plated iron wire after the hot dip plating, thereby improving the workability (metal net workability) of laying the metal net. In this way, the industrial contribution of this invention is very remarkable.

1 is a manufacturing step of a Zn-Al plated iron wire according to an embodiment of the present invention.
2 is a structure of Zn-Al plating according to one embodiment of the present invention.
3 is a diagram showing the relationship between the fractal dimension and the rating of the surface properties of the plating lines.

In the manufacturing method of the Zn-Al plated iron wire which concerns on one Embodiment of this invention, the wire rod (hot wire, a wire before processing) after hot rolling is wire-drawn so that it may become a desired wire diameter, and a pickling, surface adjustment process, and a flux process are performed, Iron wires are immersed in the molten Zn-Al plating bath and pulled up to cool the plated iron wires. In addition, when manufacturing an iron wire, hot rolling and wire drawing may be performed by a normal method. In addition, an iron wire may be annealed for soft nitriding as needed.

In this embodiment, as illustrated in FIG. 1, it is not necessary to perform plating pretreatment such as hydrogen annealing that maintains the active state of the base material surface. Therefore, as plating pretreatment, at least pickling and flux treatment may be performed. The pickling furnace cleans the surface of the iron wire. In addition, in order to activate the surface of the base material after pickling, the base material (iron wire) is passed through the flux and the flux treatment is performed. In addition, a flux process is a process of immersing an iron wire in the aqueous solution flux containing chloride and drying.

After the flux treatment, the iron wire is immersed in the molten Zn-Al plating bath, pulled up, and cooled to prepare a plated iron wire. When the iron wire subjected to the flux treatment is immersed in the molten metal (plated metal), Cl ⁻ ions are generated to clean the surface of the iron wire. As a result, stable plating can be performed on the surface of the iron wire.

Moreover, after pulling up an iron wire from a plating bath, you may adjust plating amount with a wiping apparatus (plating amount adjustment part). Moreover, in order to ensure slip resistance, you may cold-process (release shaping | molding) of a Zn-Al plating wire as needed, may form uneven | corrugated (release part) on the surface of a plating layer, and may wind up and manufacture a release plating iron wire. .

If flux is not uniformly present on the surface of the iron wire by the flux treatment, the cleaning effect of the surface of the base material by the flux becomes uneven and non-plating is likely to occur. Therefore, in order to make this flux uniform on the surface of an iron wire, the surface property of the iron wire before a flux process is adjusted. If the unevenness (complex surface, fractal interface) is formed on the surface of the wire to be plated before the flux treatment, the aqueous solution flux is stored in the recess, so that the flux is appropriately adjusted to cover the entire circumference and the entire length of the wire to be coated. It can attach uniformly. In particular, the flux can be stably secured to the fine and complicated concave portion (concave portion of the fractal). As a result, Zn-Al plating can be formed stably and uniformly in the circumferential direction and the longitudinal direction.

In addition, by controlling the annealing temperature and annealing time at the time of annealing, controlling the immersion time and pickling conditions at the time of pickling, or performing surface adjustment treatment such as sand blasting or shot blasting inline, the surface properties of the steel wire before the flux treatment are controlled. can do. Moreover, in the manufacturing method of the Zn-Al plated iron wire which concerns on this embodiment, since a molten Zn-Al plated iron wire is manufactured by the one bath process (one bath method) which performs molten Zn-Al plating after a flux process, The growth of the Fe-Al-based alloy generating layer generated at the interface portion of the Zn-Al plating layer can be suppressed.

The present inventors discovered that the structure of the Al-Zn plating layer (plating layer) of Zn-Al plating iron wire manufactured using the hot-dip plating bath affects workability, plating adhesiveness, and fatigue characteristics. The Zn-Al plating layer (plating layer) of this Zn-Al plating iron wire contains a Zn-Al type alloy layer and the Fe-Al type alloy generation layer produced | generated on the surface of an iron wire (base material). The Fe-Al-based alloy generating layer (Fe-Al-based intermetallic compound generating layer) formed at the interface between the iron wire and the plating layer mainly includes columnar crystals of Al ₅ Fe ₂ and Al _3.2 Fe. In addition, in this Fe-Al type alloy formation layer, Zn and Zn-Al alloy may exist in a grain boundary. The Fe-Al-based alloy generating layer is a layer containing at least an intermetallic compound such as Al ₅ Fe ₂ , Al _3.2 Fe, Fe ₃ Si ₂ Al ₁₂ , Fe ₂ Si ₂ Al ₉ . The thickness of the Fe-Al-based alloy generating layer has a great influence on the fatigue life (fatigue characteristics) and plating adhesion of the plated iron wire. That is, since the Fe-Al-based alloy generating layer is hard, when the Fe-Al-based alloy generating layer is thick, cracking occurs easily in the Fe-Al-based alloy generating layer when stress is applied to the plated iron wire. When the Fe-Al-based alloy generating layer is broken, the plating is peeled off or the crack is advanced into the base iron (iron wire), so that workability and fatigue characteristics are deteriorated. Therefore, it is necessary to increase the cooling rate after hot-dip plating and to suppress the growth of the Fe-Al-based alloy generating layer. However, the Fe-Al-based alloy generating layer improves the adhesion (bonding property) of the interface portion of the base material and the plating layer and improves the plating adhesion. Therefore, the Fe-Al-based alloy generating layer is preferably thinly formed with an average thickness of 0.001 µm or more and 5 µm or less.

Therefore, the inventors of the present invention provide the plating bath according to the present embodiment in order to further suppress the growth of the Fe-Al-based alloy generating layer generated at the interface portion of the plating layer containing iron wire (coated iron wire) and Zn-Al as a main component. The component was examined in detail. As a result, the present inventors found that the addition of Si to the molten Zn-Al plating bath is effective in order to further suppress the formation of the Fe-Al-based alloy generating layer at the interface between the plated iron wire and the plating layer. In addition, although the reason is not clear, Zn-Al plating became more uniform by addition of Si to a molten Zn-Al plating bath, and it turned out that the quality defects, such as non-plating, are hard to generate | occur | produce.

When Si is added to the molten Zn-Al plating bath, a Fe-Al-based alloy generating layer (Fe-Al-Si-based alloy generating layer) containing Fe-Al-Si-based alloy is formed at the interface between the plated iron wire and the plating layer. Is formed. The Fe-Al-based alloy generating layer mainly includes columnar crystals of Al ₅ Fe ₂ and Al _3.2 Fe and granular crystals of Al-Fe-Si. In addition, in this Fe-Al type alloy formation layer, Zn and Zn-Al alloy may exist in a grain boundary.

Moreover, the present inventors discovered that the Zn-Al type alloy layer of the plating layer of Zn-Al plating iron wire affects workability and fatigue characteristics. The Zn-Al-based alloy layer in the plating layer includes an Al rich phase having a face-centered cubic structure (fcc) mainly composed of Al and Zn, and a Zn rich phase having a hexagonal closest structure (hcp) having mainly Zn. In addition, as illustrated in FIG. 2, this Zn-Al alloy layer includes a eutectic structure and includes an initial crystal (primary Al phase) or an initial crystal (primary Zn phase) of an Al rich phase or a Zn rich phase. You may also Here, the Al rich phase is an αAl phase (including α ₁ Al phase) in which Zn is dissolved, and is an initial Al phase unless otherwise specified. In addition, a Zn rich phase is a Zn phase which melt | dissolved Al, and is an initial Zn phase unless there is particular notice. The primary tablet is a primary Al phase or primary Zn phase unless otherwise specified. According to the inventors' review, when the primary crystal (primary Al phase or primary Zn phase) of the Zn-Al alloy layer is coarsened, the primary crystal (primary Al phase or primary Zn phase) and the process structure are formed when the plated iron wire is bent. It was found that cracks occurred in the Zn-Al alloy layer along the boundary of. Therefore, it is preferable that a primary tablet has a fine structure (grain diameter).

In addition, when constructing cage mats for revetment construction and rhombic metal meshes used for rock fall prevention and reinforcement, workers move on cage mats or rhombic meshes. In the case where the hot-dip galvanized iron wire is used for the above application, slip resistance is required so that an operator's foot does not slip during construction. In order to improve slip resistance, it is conceivable to provide a projection or the like on the surface of the Zn-Al plating. For example, when plating is performed on the hot release wire rods used for structural materials such as reinforcing bars, a hot-dip iron wire having irregularities (for example, grooves) on the surface of the plating layer can be easily obtained.

However, when hot plating is performed on the hot release wire rod, the plating of the bottom (concave portion) of the groove is formed very thick, but the plating of the convex portion is formed very thin. Therefore, uniform plating cannot be formed, the unevenness | corrugation of the surface of a plating layer becomes small, and it is difficult to improve slip resistance. Therefore, after performing hot-dip plating on the wire rod (iron wire), it is preferable to process the surface of the plated iron wire to form irregularities.

However, as a result of the inventors' examination, for example, when cold work such as the above-mentioned surface work is performed on Zn-Al plated iron wire, if the Fe-Al-based alloy generating layer is thick, cracks are formed in the Fe-Al-based alloy generating layer. It was easy to find out. Therefore, plating peels locally and the corrosion resistance of Zn-Al plating iron wire falls. Therefore, when the 1 bath method of this embodiment is applied to the manufacturing method of a Zn-Al plated iron wire, the growth of the Fe-Al type alloy formation layer in the interface part of a base material of a Zn-Al plated iron wire and a plating layer is suppressed, and it is cold By processing, irregularities (release parts) can be stably formed on the surface of the plating layer. In addition, the inventors of the present invention also have a ratio of width and depth (concave shape ratio) and per unit area to concave and convex shapes formed on the surface of the Zn-Al plated iron wire to secure substantially slip resistance, rather than surface roughness. It was found that the number of recesses was important.

In addition, the present inventors have found that the stability of the flux treatment is increased by forming predetermined irregularities (complex surface, fractal interface) on the surface of the iron wire (base metal) before plating. Since the wettability of plating improves by the stability of this flux, adjustment of plating amount (plating time) becomes easy, and the structure of a plating layer can be controlled easily. For example, by shortening the plating immersion time of the base material and increasing the cooling rate after immersion, the Fe-Al-based alloy generating layer can be formed thin, and the primary crystals (primary Al phase or primary Zn phase) can be refined. Moreover, since the interface of a base material and a plating layer is complicated, the plating adhesiveness of Zn-Al plating iron wire will improve. In addition, since the oxide can be effectively removed from the plating surface and during plating, a clean plating layer surface can be obtained, and surface cracks and surface roughness hardly occur even during processing.

Hereinafter, the Zn-Al plating iron wire which concerns on one Embodiment of this invention is demonstrated in detail.

First, the composition of Zn-Al plating (plating layer) of the Zn-Al plating iron wire of this embodiment is demonstrated. Zn-Al plating in the present embodiment is a Zn-Al-based alloy layer mainly composed of a Zn-Al-based alloy (solid solution) and a Fe-Al-based intermetallic compound or a Fe-Al-Si-based intermetallic compound. It mainly contains a Fe-Al-based alloy generating layer mainly. The Fe-Al-based alloy generating layer is formed at the interface between the base material of the Zn-Al plated iron wire and the plating layer. Therefore, Zn-Al plating (plating layer) contains the components of a Zn-Al type alloy layer and a Fe-Al type alloy generation layer. Below, the component of a plating layer is demonstrated in detail.

Al is not a sacrificial method, but an element that increases corrosion resistance by forming a dense oxide film on the surface of the plating. In order to improve the corrosion resistance of Zn-Al plating, it is necessary for Zn-Al plating to contain 3% or more of Al. In addition, it is preferable that Zn-Al plating contains 6% or more of Al. The 6% Al amount corresponds to the process point of the Zn-Al binary alloy. Therefore, in Zn-Al plating containing 6% or more of Al, at the time of solidification, the Al rich phase is crystallized before the Zn rich phase, the plating surface is prevented by a dense oxide film, and the corrosion resistance is remarkably improved. In addition, in order to increase the Al rich phase and increase the corrosion resistance, the Al content of the Zn-Al plating is more preferably 8% or more.

Increasing the amount of Al in the plating layer increases the effect of improving corrosion resistance. However, when Al amount exceeds 15%, the improvement effect of corrosion resistance will be saturated, melting | fusing point of plating will increase to over 450 degreeC, and it becomes disadvantageous at the point of operation. Moreover, when the amount of Al in a plating layer is made into 15% or less, the structure (for example, primary Al phase) in a plating layer can fully be refined. Therefore, the upper limit of Al amount of Zn-Al plating is restrict | limited to 15%. The amount of Al in the Zn-Al plating layer can be controlled by the Al concentration in the plating bath.

Fe contained in the Zn-Al plating (plating layer) is introduced by diffusion from the surface of the iron wire toward the plating layer, and forms a Fe-Al-based alloy generating layer mainly containing Fe and Al at the interface between the iron wire and the plating layer. . Therefore, Fe in Zn-Al plating changes with the thickness of the Fe-Al type alloy formation layer. When Fe in Zn-Al plating exceeds 3.0%, since a Fe-Al type alloy formation layer is too thick, fatigue property tends to deteriorate. Therefore, in order to make the adhesiveness of an iron wire and a plating layer, and the fatigue characteristic of a plating iron wire compatible, the amount of Fe in Zn-Al plating is restrict | limited to 3.0% or less.

Moreover, in order to improve a fatigue characteristic more, it is preferable to make thickness of the Fe-Al system alloy generation layer thin. Therefore, it is more preferable to limit the amount of Fe in Zn-Al plating to 2.0% or less. On the other hand, when the Fe-Al-based alloy generating layer is formed at the interface between the iron wire and the plating layer, the iron wire and the plating layer are in close contact with each other. Therefore, it is preferable that 0.01% or more of Fe is contained in Zn-Al plating.

In addition, Zn-Al plating iron wire may contain Si in a Zn-Al plating layer as a selection element. In order for the effect as a selection element mentioned above to be exhibited, the amount of this Si may be 0.01% or more and 3.0% or less. Moreover, even if less than 0.01% of Si is included as an unavoidable impurity in the plating layer, the corrosion resistance, workability, and slip resistance of the Zn-Al plated iron wire can be improved. Si is an element which suppresses the growth of the Fe-Al type alloy generating layer which arises in the interface part (base material surface) of an iron wire and a plating layer. In order to suppress local growth of the Fe-Al-based alloy generating layer at the interface between the iron wire and the plating layer, the amount of Si contained in the Zn-Al plating is preferably 0.05% or more. When the plating layer contains 0.05% or more of Si, Zn-Al plating is more uniformly adhered to prevent unplating. In addition, when the amount of Si in the Zn-Al plating is 2.0% or less, the effect of suppressing an increase in the thickness of the Fe-Al-based alloy generating layer increases with an increase in the amount of Si. However, as the amount of Si of Zn-Al plating increases, the plating layer itself becomes hard, and fatigue strength falls. Therefore, it is preferable to limit the upper limit of the amount of Si of Zn-Al plating to 2.0% or less. In order to ensure fatigue strength further, it is more preferable to limit the upper limit of the amount of Si of Zn-Al plating to 1.5% or less.

In addition, when the plating layer contains Si, the influence of the temperature of the plating bath and the cooling rate of the plating layer on the growth of the Fe-Al-based alloy generating layer is alleviated. Therefore, when the temperature of the plating bath is high or the cooling rate of the plated iron wire is slow, it is very effective to contain Si in the plating layer in order to suppress the growth of the Fe-Al-based alloy generating layer.

In the case where Si is included in the Zn-Al plating, the Fe-Al-based alloy generating layer in the Zn-Al plating (plating layer) adds Fe-Al-Si granular crystals in addition to the Fe-Al-based intermetallic compound. Include. Therefore, in this case, Zn-Al plating (plating layer) mainly consists of a plating layer mainly composed of Zn-Al-based alloys (solid solutions), Fe-Al-based intermetallic compounds and Fe-Al-Si-based granular crystals. It mainly comprises a Fe-Al-based alloy generating layer (Fe-Al-Si-based alloy generating layer).

Among the chemical components of the Zn-Al plating, the remaining portion excluding Al, Fe, and Si contains Zn and unavoidable impurities. Here, unavoidable impurities are elements which are inevitably mixed in the plating process, for example, Mg, Cr, Pb, Sb, Sn, Cd, Ni, Mn, Cu, Ti, and the like. Here, when Si is not intentionally added to the plating bath, Si exists as an unavoidable impurity in the plating layer. Moreover, it is preferable to restrict content of the said unavoidable impurity to 1% or less in total.

The chemical component of Zn-Al plating (plating layer) can be analyzed, for example by the following method. For example, a Zn-Al plated iron wire is immersed in an acid to which a pickling corrosion inhibitor is added at room temperature for several minutes to dissolve Zn-Al plating, and then the chemical component of the solution is inductively coupled plasma (ICP) emission spectroscopy or atomic Analyze by absorption method. Moreover, as a method of melt | dissolving a plating layer, the method shown by JIS H0401 (or ISO1460) can also be applied to chemical analysis. For example, a solution obtained by dissolving hexamethylenetetramine in hydrochloric acid is diluted with water to prepare a test solution, the plating is dissolved in this test solution, and the solution is analyzed by ICP emission spectroscopy. In these methods, the plating layer (Zn-Al-based alloy layer and Fe-Al-based alloy generating layer) can be dissolved in the test solution while suppressing dissolution of the base metal in the test solution. In addition, the plating iron wire may be subjected to processing such as bending, the plating layer may be mechanically peeled from the iron wire, and the chemical component of the Zn-Al plating that has been peeled off may be measured by chemical analysis. The analysis method of the chemical component of Zn-Al plating (plating layer) will not be restrict | limited especially if it is a method which can analyze with high precision. In view of analysis accuracy, chemical analysis such as ICP emission spectroscopy or atomic absorption method described above is suitably used.

Next, the structure of the Zn-Al alloy layer of Zn-Al plating is demonstrated. Here, a Zn-Al alloy layer is a layer which mainly contains the Al rich phase and Zn rich phase which are solid solutions.

The structure of a Zn-Al alloy layer is a coagulation structure, and mainly contains the primary crystal | crystallization which precipitates in a granular form, and the structure (process structure) in which the liquid phase which filled in between was solidified. For example, when the molten Zn-Al of an over eutectic component of a concentration larger than the Al concentration (6%) corresponding to the process point of the Zn-Al binary alloy is cooled, the Al rich phase (the primary tablet) is used as the primary tablet. Al phase) is crystallized. Thereafter, with the passage of time, the Al rich phase (primary Al phase) grows and solidifies in the form of a structure in which the process structure is surrounded by a net shape around it. Further, for example, when the molten Zn-Al of the sub-process component having a concentration smaller than the Al concentration (6%) corresponding to the process point of the Zn-Al binary alloy is cooled, the Zn rich phase ( Primary Zn phase) is determined. Also in this case, Zn rich phase (primary Zn phase) grows with time, and it solidifies in the form of the structure | tissue surrounding process structure around the Zn rich phase (primary Zn phase) in mesh shape.

When the primary crystal (primary Al phase or primary Zn phase) becomes coarse, the interface between the primary crystal (primary Al phase or primary Zn phase) and the process structure becomes a starting point for cracking and peeling of the plating, and the fatigue strength is lowered. Therefore, it is preferable to limit the average diameter of the primary tablet in a Zn-Al alloy layer to 10 micrometers or less so that a primary tablet does not adversely affect fatigue strength. Moreover, in order to raise fatigue strength, it is more preferable to limit the average diameter of a primary tablet to 5 micrometers or less. This crystal | crystallization can be refine | miniaturized by reducing the temperature of a plating bath, making the cooling rate of the plating iron wire after plating quick, or adjusting the temperature of the plating bath and the cooling rate of the plating iron wire after plating suitably. Therefore, in the case where the average diameter of the primary tablet is set to 10 µm or less, it is necessary to perform hot-dip plating using a low temperature plating bath, pull the iron wire out of the plating bath, and then cool the plated iron wire at a high cooling rate. The lower limit of the average diameter of the primary tablet is preferably 1 µm because of limitations in operation such as the temperature of the plating bath and the cooling rate after plating.

The shape of the primary tablet (primary Al phase or primary Zn phase) (shape in cross section) may be circular, but usually elliptical. When the primary tablet is elliptical, the diameter of the primary tablet is obtained by averaging the long and short diameters. In addition, you may image-process the SEM image (structure | tissue photograph) of a plating layer, and may calculate | require the diameter of a tablet as a circle equivalent diameter. Moreover, when the cooling rate of the plating iron wire after plating is fast, the form of a crystal may become dendrite form. In this case, the diameter of the primary tablet is measured as the width (paper width) of the dendrite. The diameter of this primary tablet can be measured using SEM. In this embodiment, a SEM photograph is used to take a tissue photograph of 10 times or more at 2000 times to measure the diameter of the primary tablet, and the average value (average diameter) is obtained.

Moreover, the Fe-Al type alloy generating layer produced | generated at the interface part of a base material (iron wire) of Zn-Al plating (plating layer), and a plating layer is demonstrated.

If the average thickness of the Fe-Al type alloy generating layer which exists in the interface part of an iron wire and a plating layer is 5 micrometers or less, the fatigue characteristic of a Zn-Al plating iron wire is enough. Therefore, it is preferable to limit the upper limit of the average thickness of the Fe-Al type alloy formation layer to 5 micrometers. In addition, the average thickness of the Fe-Al-based alloy generating layer becomes thin, and the fatigue characteristics of the Zn-Al plated iron wire are improved. Therefore, it is more preferable that the average thickness of the Fe-Al type alloy formation layer is 3 micrometers or less. On the other hand, in order to improve the adhesiveness of Zn-Al plating and iron wire, it is preferable that the minimum of the average thickness of the Fe-Al type alloy formation layer is 0.001 micrometer or more. Moreover, when improving the plating adhesiveness of a Fe-Al type alloy generation layer by the multilayer structure mentioned later, it is more preferable that the minimum of the average thickness of a Fe-Al type alloy generation layer is 0.05 micrometer or more. When the average thickness of the Fe-Al-based alloy generating layer is 5 μm or less, the Si content in the plating bath is increased, the temperature of the plating bath is decreased, or the immersion time of the plated iron wire in the plating bath is shortened. The cooling rate of the plated iron wire after plating is accelerated or these methods are combined.

In this embodiment, the average thickness of the Fe-Al type alloy generating layer is calculated | required using a transmission electron microscope (TEM). According to the thickness of the Fe-Al-based alloy generating layer, TEM is observed at a magnification of 5000 to 20,000 times, and a tissue photograph of 10 or more fields is taken according to this magnification. The average value (average thickness) of the thickness of the Fe-Al type alloy formation layer is calculated | required from these structure | tissue photographs. In addition, the presence of the Fe-Al-based alloy generating layer in the interface portion between the plating layer and the iron wire (base metal) can be confirmed from the structure observation by TEM and elemental analysis by energy dispersive X-ray spectroscopy (EDS). In addition, the Fe-Al-based alloy generating layer can also be confirmed by a high resolution electrolytic emission scanning electron microscope (FE-SEM) and EDS.

The Fe-Al-based alloy generating layer present at the interface between the molten Zn-Al plating (plating layer) and the iron wire mainly includes a layer of columnar crystals of Al _3.2 Fe and a layer of columnar crystals of Al ₅ Fe ₂ . That is, Fe-Al-based alloy produced layer has a multi-layer structure, the layer (lower layer) of the wire side, containing the Al ₅ Fe ₂ increase the Fe content of alloying with a high degree of mainly, plating the front surface of the layer (upper layer), the alloying Low Al _3.2 Fe is mainly included. If such a multilayer structure is formed in the Fe-Al-based alloy generating layer, it is assumed that the internal stress in each layer and the stress difference between the interface between the lower layer and the upper layer are reduced, and the plating adhesion is further improved.

In addition, the columnar crystals of Al ₅ Fe _{2 and} the columnar crystals of Al _3.2 Fe can be identified by specifying the crystal structure from the structure observation and electron beam diffraction using TEM. In addition, Zn is also included in the Fe—Al-based alloy generating layer. This Zn exists in the grain boundary in an Al-Fe type alloy formation layer, for example as Zn and Zn-Al alloy.

In addition, when Si is contained in Zn-Al plating, the Fe-Al type alloy formation layer in Zn-Al plating (plating layer) contains Fe-Al-Si type | mold crystal grains. Therefore, in this case, the Fe-Al-based alloy layer (Fe-Al-Si-based alloy layer) of the Zn-Al plated iron wire mainly includes a layer of columnar crystals of Al _3.2 Fe and a layer of columnar crystals of Al ₅ Fe ₂ . The columnar crystal layer and the Al-Fe-Si granular crystal layer (granular crystal layer) are mainly included. It is estimated that the Al-Fe-Si-based granular crystal layer suppresses the growth of the columnar crystal layer, alleviates the stress difference between the columnar crystal layer and the Zn-Al alloy layer, and exhibits good adhesion. In addition, by specifying the crystal structure from the structure observation and electron beam diffraction using TEM, the columnar crystals of Al ₅ Fe _2, the columnar crystals of Al _3.2 Fe and the Al-Fe-Si granular crystals can be identified. In addition, Zn is also included in the Fe—Al-based alloy generating layer (Fe—Al—Si-based alloy layer). This Zn exists in the grain boundary in an Al-Fe type alloy formation layer, for example as Zn and Zn-Al alloy.

Therefore, when Zn-Al plating contains Si, between Al-Fe- and the Zn-Al alloy layer mainly containing the columnar layer of Al _3.2 Fe and the columnar layer of Al ₅ Fe ₂ mentioned above, Al-Fe- A layer (granular crystal layer) mainly containing Si-based granular crystals is produced.

Therefore, in Zn-Al plating which added Si, it can be considered that the granular crystal layer suppresses the diffusion of Fe from the iron wire to Zn-Al plating and suppresses the growth of the columnar crystal layer. In particular, the influence of the temperature of the plating bath and the cooling rate of the plated iron wire on the formation of the granular crystal layer containing Si is small. Although this cause is not clear, even when the temperature of a plating bath and the cooling rate of a plating iron wire change, the growth of a Fe-Al type alloy layer can be suppressed by formation of a granular crystal | crystallization by containing Si. In addition, since the granular crystal layer relaxes the stress difference between the columnar crystal layer and the Zn-Al alloy layer, it is estimated that more favorable plating adhesion is expressed.

In addition, by specifying the crystal structure from the structure observation and electron beam diffraction using TEM, the columnar crystals of Al ₅ Fe _2, the columnar crystals of Al _3.2 Fe and the Al-Fe-Si granular crystals can be identified. Moreover, in the Fe-Al type alloy layer, the phase mainly containing a fine granular Zn or Zn-Al alloy may exist. The phase mainly containing this Zn or Zn-Al alloy is present at the grain boundaries of each columnar crystal of Al _3.2 Fe, the grain boundary of each columnar crystal of Al ₅ Fe ₂ , the interface between the upper and lower layers of the columnar crystal layer, and the interface between the columnar crystal layer and the granular crystal layer. do.

Moreover, in this embodiment, since a flux is made to adhere uniformly to the surface of a to-be-plated iron wire, the unevenness | corrugation (fractional interface) is formed in the surface of a to-be-plated iron wire. In order to quantify the shape of the unevenness, the unevenness at the interface between the base material (iron wire) of the molten Zn-Al plated iron wire and the plating layer is measured by a box counting method, and the shape of the unevenness is evaluated using the fractal dimension. The fractal dimension is an index indicating the complexity of the shape, and is 1 when there are no irregularities. In the case where the irregularities are similar, the fractal dimension is the same regardless of the size of the irregularities.

In FIG. The relationship between the fractal dimension and the rating of the surface property of the plated wire is shown. Here, the rating of the surface properties of the plated wires is determined in six stages of 0 to 5 depending on the number of defects (surface roughness, unplating) of surface properties per length of 1 m. In other words, the number of defects (surface roughness, non-plating) of surface properties per 1m in length was found to be "0 (flat 5)", "1 or more 2 or less (flat 4)", "more than 2, 5 Plating is divided into six stages of &quot; (Rating 3) &quot;, &quot; Rating more than 5 and 10 or less (Rating 2) &quot;, &quot; Running more than 10 and 20 or less (Rating 1) &quot; The grade of the surface property of a line is determined. In addition, in FIG. 3, this rating is determined once or more, and the determined rating is averaged. In addition, when the rating was less than 2, the plating wire was evaluated as "defect".

If the fractal dimension determined by the box counting method is less than 1.05, the surface of the plated iron wire is smooth, so that the flux treatment is uneven and local unplating may occur. For example, as shown in FIG. 3, when the fractal dimension was less than 1.05, the grade of the surface property of a plating wire was less than two. Therefore, the fractal dimension of the surface of the wire to be plated is 1.05 or more. In addition, when the fractal dimension is increased, the flux treatment property is improved, and the plated layer and the plated iron wire tend to fuse. Therefore, control of plating adhesion amount and structure control of a plating layer can be performed easily. In addition, even when a plated iron wire is processed strongly, peeling of a plated layer and a to-be-plated iron wire can be prevented. However, as shown in FIG. 3, when the fractal dimension exceeds 1.30, the stability (flux treatment property) of plating adhesion is saturated. Therefore, considering the cost for forming the unevenness, the fractal dimension is preferably 1.30 or less.

The measurement of the fractal dimension by the box counting method is performed as follows. First, a to-be-plated iron wire or a plated iron wire is cut | disconnected in any cross section of a cross section (diameter direction) or a longitudinal cross section (axial direction), and the cross section is polished. This polished surface is observed by an optical microscope or SEM, and the photograph of the unevenness | corrugation of the surface of a to-be-plated iron wire, or the unevenness | corrugation of the base material of a plated iron wire and the plating layer is taken. In the case where the unevenness of the surface of the plated iron wire or the unevenness of the base material of the plated iron wire and the interface of the plating layer is not clear, the unevenness (fractal interface) of the photographed photograph is traced to show the shape of the unevenness as a line.

Next, a square mesh having a length of one side (mesh size) r is superimposed on a photograph or trace of unevenness, and the number [N (r)] of the mass (square of the mesh) where one side of the uneven line intersects with the mesh crosses. . At this time, with respect to the size r of five or more types of meshes, the number N (r) of the masses where the uneven line intersects with one side of the mesh is counted. The relationship between the number of masses N (r) and the length r of one side of the mesh is plotted on both logarithmic graphs.

When the relationship of the following formula (1) is established between the counted mass number N (r) and the length r of one side of the mesh, it is determined that the shape of the unevenness is fractal.

The fractal dimension is the exponent (D) of Equation (1). In the case of fractionality, the relation between the number of masses [N (r)] and the mesh size (r) is approximated by the least square method to obtain the value of the exponent (D) of Equation (1). Let the value of) be the fractal dimension.

Moreover, in order to improve corrosion resistance, it is preferable that the plating adhesion amount of a Zn-Al plating iron wire is 100 g / m <2> or more. When the plating adhesion amount of a plated iron wire increases, corrosion resistance improves and a lifetime becomes long. In practice, however, since corrosion products are formed on the plating surface, the corrosion rate is lowered, and the effect of improving corrosion resistance (for example, the effect of the sacrificial method by Zn) is saturated. Therefore, in order to suppress manufacturing cost while improving corrosion resistance, it is preferable that the plating adhesion amount of a plated iron wire is 400 g / m <2> or less. In addition, the plating adhesion amount of a Zn-Al plating iron wire can be controlled by wiping. This plating adhesion amount is based on the difference between the mass before dissolving the Zn-Al plating (plating layer) of the Zn-Al plated iron wire (plating layer) according to the indirect method of JIS H 0401 (or ISO 1460), and the mass after dissolving the plating layer. Obtained indirectly

For example, when using a hot-dip galvanized iron wire as the above-mentioned rhombus type metal mesh, in order to improve slip resistance, it is preferable to form an unevenness | corrugation (release part) in the surface of Zn-Al plating (plating layer). Do. The shape of the unevenness seen from the radial direction of the plated iron wire is not particularly limited. If the shape of the recess is a circle, an ellipse or a rectangle, it is easy to form a stable and continuous recess on the surface of the plated wire. Therefore, it is preferable that the shape of a recessed part is a circle, an ellipse, and a rectangle. Moreover, in order to improve slip resistance, it is preferable that the lower limit of the concave portion ratio is 0.1 or more, the lower limit of the depth of the concave portion is 0.2 mm or more, and the number of the concave portions is 1 / cm 2 or more and 100 / cm 2 or less. On the other hand, in order to prevent peeling of plating, it is preferable that the upper limit of recess shape ratio is three or less. Moreover, it is preferable that the upper limit of the depth of a recessed part is 0.5 mm or less from a viewpoint of workability.

When the surface opening width of a recess is 1 mm or more, the depth of a recess can be measured with a dial gauge or a depth gauge. When the surface opening width of the concave portion is less than 1 mm, the plated iron wire is cut into a cross section perpendicular to the linear axis of the plated iron wire, and after polishing the cross section, the depth of the concave portion is obtained using an optical microscope or SEM. The depth of the recess can be measured from the photographed picture or the image on the monitor.

In addition, the number of recesses is calculated | required by counting the number of recesses which exist in the area of 1 cm <2> at the time of spreading a plated iron wire surface flat. In addition, when a part of recessed part exists in a measurement area, the recessed part is counted as one. When the number of recesses is large, the number of recesses is determined by binarizing the surface photograph of the plated iron wire using an image processing apparatus on the basis of the color tone difference between the recesses and the protrusions. Is counted and converted into the number per 1 cm <2> of measurement areas.

For example, when the number of recesses per unit area is 5 / cm 2 or less and the surface opening width is 1 mm or more, the opening width and depth of the recesses are measured using a dial gauge or a depth gauge, and the opening width of the recesses is measured. It is possible to determine the shape ratio of the concave portion from the ratio of the depth to the depth. However, if the number of recesses per unit area exceeds 5 / cm 2, measurement by dial gauge or depth gauge is difficult, so that the cross section of the plated iron wire is polished similarly to the measurement of the depth of the recesses, and the shape ratio of the recesses is determined by microscopic observation. Measure

The chemical composition of the iron wire which is a base material of the Zn-Al plating iron wire in this embodiment is demonstrated. In this embodiment, it does not specifically limit about the chemical composition and structure of a base material. However, when using the Zn-Al plated iron wire in this embodiment as a raw material of a metal network, it is preferable that a base material (iron wire) has a chemical composition as follows.

C is an element which raises the strength of steel materials. In order to ensure the strength of Zn-Al plated iron wire and to use it as a metal net for practical use, it is preferable to add C or more than 0.01% in the base material. On the other hand, when C is added excessively, Zn-Al plating iron wire strength will become high and the load at the time of netting a metal net will become large, and workability will fall. Therefore, in order to ensure sufficient workability, it is preferable that C amount is 0.70% or less. In the metal structure of steel materials whose amount of C is 0.01 to 0.70%, ferrite and pearlite are mainly contained when it cools. Within the range where the amount of C is 0.01 to 0.70%, the proportion of ferrite increases with the decrease of the amount of C, and the proportion of pearlite increases with the increase of the amount of C. When the amount of C exceeds 0.70%, the pearlite and cementite are mainly included in the metal structure when cooled.

Si is added for deoxidation and is an element which improves the strength of steel by solid solution strengthening. In order to obtain sufficient properties (strength and surface properties) of the metal mesh, it is preferable to add 0.1% or more of Si in the base metal. On the other hand, when an excessive amount of Si is added, the scale generated on the surface of the plated iron wire becomes difficult to be removed, thereby degrading the plating property due to the generation of non-plating. Therefore, the amount of Si is preferably 1.0% or less so that the scale can be sufficiently removed.

Mn is added for deoxidation and desulfurization, and is an element that increases the strength of Zn-Al plated iron wire by improving the hardenability. In order to sufficiently secure the strength of the Zn-Al plated iron wire, it is preferable to add 0.1% or more of Mn. On the other hand, when Mn is added excessively, hard phases, such as martensite and bainite, which are supercooled structures, are generated in the base material in the cooling process after annealing. As a result, a base material is disconnected at the plating process or the workability at the time of metal mesh processing falls. Therefore, in order to ensure sufficient toughness and workability, it is preferable that Mn amount is 1.5% or less.

Moreover, in order to refine | miniaturize the structure of the base material of a hot-dip iron wire, and to improve toughness, you may add at least 1 sort (s) of Al, Ti, and B.

Al is an element which is added to the base material as a deoxidizer and contributes to the refinement of the structure by deposition of nitride. In order to improve the toughness of the Zn-Al plated iron wire and improve the workability at the time of netting, it is preferable to add Al or more. On the other hand, even if it adds excessively, the improvement effect of toughness will be saturated. Therefore, in order to suppress cost while securing toughness, it is preferable that Al amount is 0.10% or less. In addition, since the solid solution nitrogen in steel materials is reduced by formation of nitride, addition of Al is effective also in suppressing the increase of the tensile strength of Zn-Al plated iron wire by strain aging.

Ti, like Al, is added to the base metal as a deoxidizer and forms carbonitrides and contributes to the refinement of the structure. In order to improve the toughness of the Zn-Al plated iron wire by making the structure of the base material finer, and to improve the workability at the time of netting, it is preferable to add Ti or more. On the other hand, even if Ti is excessively added, the effect of improving toughness is saturated. Therefore, in order to suppress cost while securing toughness, it is preferable that Ti amount is 0.10% or less. In addition, since the formation of carbonitride reduces the dissolved carbon and the dissolved nitrogen in steel, it is also effective in suppressing strain aging.

B is an element which forms nitride (BN) or complex precipitates of Fe and C (Fe ₂₃ (C, B) ₆ ). Similarly to Al and Ti, it is preferable to add B by 0.0005% or more in order to improve the toughness by miniaturizing the structure of the base metal and to improve the workability at the time of netting. On the other hand, even if B is added in excess, the effect of improving toughness is saturated. Therefore, in order to suppress cost while securing toughness, it is preferable that the amount of B is 0.0070% or less. In addition, since the solid solution nitrogen and the solid solution carbon in steel materials are reduced by formation of B precipitate (for example, said nitride and composite precipitate), it is effective also in suppressing strain aging.

When using the Zn-Al plated iron wire in this embodiment as a raw material of a metal network, it is preferable that a base material (iron wire) contains the said element and has a chemical composition which contains iron and an unavoidable impurity in remainder. . In particular, the Zn-Al-plated iron wire in the above embodiment using a plated iron wire (low C iron wire) having a low C content is a metal used for the purpose of preventing falling rocks of rivers and harbors, artificial slopes (surfaces), etc. It can use suitably as a material of a net | network. In this case, it is preferable that a base material has a structure containing ferrite, and it is more preferable to have a structure containing ferrite and cementite. In addition, in this embodiment, the case where Zn-Al plated iron wire is used as a raw material of a metal net was demonstrated. However, when using it as a high strength wire rod, you may contain 0.7% or more and 1.2% or more C, for example. Thus, the component of a base material can be suitably determined according to the use of a wire rod. Here, an iron wire means the wire material which mainly contains iron. In addition, the wire diameter of an iron wire may be 1 mm or more, and may be 10 mm or less.

Next, the manufacturing method of the hot-dip iron wire in this embodiment is demonstrated in detail based on FIG. In addition, a to-be-plated iron wire is manufactured by the other process which is not shown in figure. That is, a to-be-plated iron wire is manufactured by processing the wire rod manufactured by the normal hot rolling process by cold working, such as drawing, to the target wire diameter. The plated iron wire may be softened by annealing in a step of continuous annealing as necessary. Annealing of the to-be-plated iron wire is applied as needed in order to satisfy the required characteristics, such as strength and extension | stretching. As the annealing method, a gas furnace, a radiation furnace, a fluidized bed furnace, high frequency heating, direct current heating, or the like can be adopted.

Before the plating treatment, pickling is performed to remove scale formed by annealing and lubricants attached to the surface of the wire. For example, in the pickling after annealing, an apparatus for washing the surface of the wire in a short time is mainly used by passing the iron wire in a hydrochloric acid solution. When the apparatus which can clean the surface of an iron wire by wet pickling in a short time is used, it is not limited to a specific pickling method. For example, in order to increase pickling efficiency, a method of flowing the acid solution, a method of applying ultrasonic waves, and a method of introducing micro bubbles may be applied.

After pickling, irregularities (complex surface, fractal interface) are formed on the surface of the plated iron wire by surface adjustment treatment such as shot blasting. When the unevenness is formed on the surface of the plated iron wire after pickling, the surface adjustment treatment is performed so that the fracturing dimension of the unevenness becomes 1.05 or more and 1.30 or less. Moreover, as a surface adjustment method other than shot blasting, for example, the method by various blasts which project particle | grains, such as sand, steel, glass, or the method of suspending hard particles in a liquid and applying a high pressure, for positive electrode electrolysis It is possible to employ a method of selectively dissolving locally using the iron dissolution, and a method of controlling the annealing temperature and annealing time during annealing. Moreover, by observing the unevenness of the surface of the iron wire before plating using an optical microscope or SEM, it is possible to determine whether the surface property of the plated iron wire is appropriate.

Flux is also applied to the surface of the iron wire, and the surface of the iron wire is dried. In the flux treatment, for example, zinc chloride, ammonium chloride, chlorides of alkali metals, fluorides, and tin chlorides are used. The flux contains zinc chloride as a main component and preferably contains potassium chloride and tin fluoride. This flux may further contain 1 or more types of ammonium chloride, the chloride of an alkali metal, and tin chloride. The composition of the flux is not particularly limited. For example, in an aqueous solution having a concentration of 10 to 40% of the total solute in the flux, 30 to 40% of Zn ²⁺ ions in the solute, 8 to 12% of K ⁺ ions in the solute and Sn ²⁺ ions in the solute What is necessary is just to prepare and use a flux so that the sum total of Cl <^-> ion and F <^-> ion in 2 to 3% and a solute may be 45 to 60%, and pH may exist in the range of 0.5 to 2.0. It is preferable that the immersion time in the flux of an iron wire is 0.5 second or more.

The iron wire after applying flux and drying is immersed in a molten Zn-Al bath, and the iron wire plated from this bath is pulled up in a perpendicular direction. The amount of Al in the molten Zn-Al bath is in the range of 3.0 to 15%, and is adjusted according to the amount of Al in the Zn-Al plating layer. In addition, when adding Si in a plating bath, it is preferable that the amount of Si of a molten Zn-Al bath is in 0.05 to 2% of range. In this case, Si amount of a molten Zn-Al bath is adjusted according to Si amount of a Zn-Al plating layer. The temperature (bath temperature) of a molten Zn-Al plating bath can be set in the range which does not solidify a plated metal, and is generally adjusted to around 450 degreeC. Moreover, the plating adhesion amount of a plated iron wire is adjusted with the wiping apparatus arrange | positioned just above the wire drawn up from a plating bath. In addition, within 3 s from immediately after the iron wire emerges from the plating bath, the iron wire is quenched to below the solidification temperature of the molten metal (plated metal) by the cooling device. By the method mentioned above, the hot-dip iron wire which concerns on the said embodiment can be manufactured. In addition, the composition of a molten Zn-Al plating bath can be calculated | required by taking a sample from a plating bath, dissolving this sample in hydrochloric acid stock solution (35% hydrochloric acid), and performing a chemical analysis.

In addition, since the viscosity of the molten Zn-Al is lower than that of the molten zinc, it is difficult to control the plating coating weight in a desired amount by using a method of wiping the plating layer by physical contact. Therefore, it is preferable to employ a non-contact wiping method. As the non-contact wiping method, for example, wiping with nitrogen gas can be applied. However, especially when plating a plurality of wire rods, it is difficult to wipe the circumference of the plated wire uniformly and stably, so that a wiping device is required for the number of wires. Therefore, it is preferable to employ the wiping method (electromagnetic wiping) by electromagnetic force as a non-contact wiping method. In the electromagnetic wiping, since the electromagnetic force can be controlled by the output of the high frequency power source, the coating weight of the coating can be easily controlled, and it is also possible to wipe a plurality of wires simultaneously, so that the wiping can be performed efficiently.

Within 3 seconds after pulling up the iron wire from the plating bath, the plating iron wire is cooled by the cooling device provided at the rear end of the wiping device, and the plating metal is solidified to obtain a plating layer having a fine process solidification structure. The cooling method of a cooling apparatus may be a method of simply spraying flowing water on a plating iron wire. In addition, when the two-fluid nozzle is applied to the cooling method of the cooling device, the controllability of the cooling rate is improved. In addition, by arranging a plurality of stages of cooling portions in the height direction with respect to the cooling apparatus, more advanced structure control can be performed with respect to the plating layer.

Moreover, in order to provide slip resistance, you may form an unevenness | corrugation (release part, concave part) in the surface of a Zn-Al plated iron wire using a surface unevenness | corrugation forming apparatus (surface unevenness formation part). The surface asperity forming apparatus (surface asperity forming portion) is not particularly limited. For example, a method of forming a concavo-convex by pressing down while passing a plated iron wire between two or more rolls having projections continuously on the surface of the roll, embossing to form finer concavities and convexities, or processing by a dull roll. And processing methods such as surface processing by laser can be applied. The surface asperity processing apparatus can be continuously installed inline. In addition, in order to form an unevenness | corrugation on the surface of a plated iron wire, after winding a Zn-Al plated iron wire with a smooth surface once, you may perform mold release process using the surface asperity processing apparatus of another process.

Although there is no restriction | limiting in particular about the strength of Zn-Al plated iron wire, In the case of a metal network use, it is preferable that the intensity | strength of a plated iron wire is low from a viewpoint of netting. In this case, strength of about 1000 MPa may be required depending on the application of the metal net. Therefore, the heat treatment method and steel component (for example, the chemical component in the above-described embodiment of the plated iron wire) of the steel are appropriately selected according to the required characteristics of the metal mesh, and the strength of 300 MPa to 1000 MPa is achieved. Zn-Al plated iron wire is applicable as a wire rod for metal network applications. Moreover, also when using a plated wire rod for uses other than a metal net use, the intensity | strength of Zn-Al plated iron wire can be suitably determined according to the use of a wire rod.

Example

The steel piece which has the chemical component shown in Table 1 was hot-rolled, and the hot rolled wire rod of wire diameter 6mm was manufactured. Next, the obtained hot-rolled wire rod was drawn to a wire diameter of 5.0 mm by die drawing using a dry lubricant to prepare a wire rod. Furthermore, after electrolytically degreasing the wire rod, annealing was carried out by passing through a fluidized bed heated at 760 ° C. using zircon sand as a heat medium to prepare a plated iron wire. The metal structure of this to-be-plated iron wire was confirmed with the optical microscope. As shown in Table 1, this metal structure was mainly one of a mixed structure of ferrite (primary ferrite) and pearlite, a ferrite structure, and a pearlite structure. In addition, the ratio of ferrite and pearlite in the mixed structure of ferrite and pearlite varied with steel types. In addition, steel types A-G (plated iron wire) of Table 1 are steel types used suitably as a metal mesh.

As the plating pretreatment, the obtained plated iron wire was subjected to pickling, sand blast treatment (surface adjustment treatment), flux treatment, and drying in order, followed by hot dip Zn-Al plating. In addition, each process was performed continuously on the same line, without inserting a separate process.

In pickling, the plated iron wire was immersed in a pickling bath having a hydrochloric acid concentration of 18% heated at 60 ° C. In the sand blasting treatment, sand particles were sprayed over the entire circumference of the pickled plated iron wire, and the irregularities (fragmental dimensions) of the iron wire surface were adjusted by controlling the particle diameter and the projection speed of the projected sand. In the flux treatment, the flux liquid in which 5 g / l of potassium fluoride was mixed in a 200 g / l zinc chloride solution was heated to 40 ° C., and the sand-blasted plated iron wire was passed through the flux liquid. 80 degreeC air was sprayed on the to-be-plated iron wire which flux was apply | coated to the surface, and the to-be-wired iron wire was dried.

After the flux treatment, the dried plated iron wire was immersed in a molten Zn-Al plating bath in which the Al amount was adjusted to form Zn-Al plating on the surface of the plated iron wire. The temperature of the molten Zn-Al plating bath was adjusted to 455 degreeC. The plated iron wire immersed in the plating bath was pulled up from the plating bath in the vertical direction, and then the plating deposition amount was controlled by an electromagnetic wiping device provided at a position 100 mm apart from the surface of the plating bath in the vertical direction. In addition, the plating layer was completely solidified by using a water cooling apparatus to prepare a Zn-Al plated iron wire.

By adjusting the line speed (line passing speed) and the water-cooling position of the plated iron wire, the time (water-cooling start time) until the plated iron wire pulled up from the surface of the plating bath starts water cooling is adjusted. Or primary Zn phase). For the prepared Zn-Al plated wire, the Al concentration and Fe concentration of the Zn-Al plated layer, the initial diameter of the Zn-Al-based alloy layer, the thickness of the alloy formation layer, the coating weight, the iron (plated iron wire) and the plated layer The fractal dimension of the interface was evaluated. In addition, the thickness of an alloy formation layer is the thickness of the Fe-Zn type alloy formation layer in pure zinc plating iron wire, and the thickness of the Fe-Al type alloy formation layer in Zn-Al plating iron wire. This result is shown in Table 2 with water cooling start time. In addition, the weight loss (corrosion resistance), surface properties, workability, and metal mesh characteristics of the manufactured Zn-Al plated iron wire were evaluated. The results are shown in Table 3.

In Examples 1-11, Al amount in a plating layer was 3.0% or more and 15.0% or less, Fe amount in a plating layer was 3.0% or less, and the fractal dimension was 1.05 or more and 1.30% or less. In the first to eleventh embodiments, the diameter of the primary tablet (primary Al phase or primary Zn phase) is 10 µm or less, the thickness of the alloy generating layer is 5 µm or less, and the plating deposition amount is 100 g / m 2 or more and 400 g. / M 2 or less. On the other hand, in the 12th to 14th and 16th comparative examples, the amount of Fe in the plating layer was more than 3.0%. In these comparative examples, in the twelfth, thirteenth and sixteenth comparative examples, a thick alloy generating layer exceeding 5 µm was formed. Moreover, in the 15th comparative example, Al amount in the plating layer exceeded 15.0%.

In the twelfth comparative example, since a hot dip galvanizing bath containing no Al was used, the Fe-Al-based alloy generating layer was not formed at the interface between the plating layer and the iron wire, and the Fe-Zn alloying reaction proceeded to increase the thick Fe-. A Zn-based alloy generating layer was formed. In Comparative Example 13, the alloy plating was performed using the two bath method, so that a thick Fe-Al-based alloy generating layer remained. In the sixteenth comparative example, since the passage speed of the iron wire was slow, and the time until the plated iron wire was pulled up from the plating bath and water-cooled was long, the alloy generating layer was growing significantly. In addition, in the twelfth comparative example, Al is not included in the plating bath, and therefore, primary crystals (primary Al phase) are not formed. In the fourteenth comparative example, since the amount of Al in the plating bath was small, the primary tablet (primary Al phase or primary Zn phase) could not be clearly identified. In Comparative Example 15, since the amount of Al in the plating bath was large, each primary Al phase could not be clearly distinguished. Therefore, in the 14th and 15th comparative examples, the diameter of the primary Al phase could not be measured. In the sixteenth comparative example, since the time until the start of water cooling was long, the primary Al phase was coarsened. In the seventeenth comparative example, the fractal dimension was less than 1.05, and the surface of the ground iron (coated iron wire) was smooth, so even if the processing time of the flux was lengthened by slowing the passage speed of the iron wire, the amount of plating adhesion was reduced and non-plating occurred. It was. In addition, in this seventeenth comparative example, since the passage speed of the iron wire was slow and the water cooling start time was longer than 3 seconds, the structure formed in the plating layer was substantially an alloy generating layer. Therefore, the diameter of the primary Al phase could not be measured. In the eighteenth comparative example, the fractional dimension was less than 1.05, and the flux treatability was lowered. In addition, in this eighteenth comparative example, Al concentration in the plating bath was low, Fe was diffused in the plating layer, and the alloy generation layer was grown. Therefore, the Al concentration in the plating layer was less than 3.0% and the Fe concentration was more than 3.0%.

In addition, the Al concentration and Fe concentration of the Zn-Al plating layer described above, the diameter of the primary crystal (primary Al phase or primary Zn phase) of the Zn-Al-based alloy layer, the thickness of the alloy generating layer, the plating adhesion amount, and the iron (plated iron wire) The fractal dimension of the interface of the plating layer was evaluated as follows.

The Al concentration and Fe concentration of the Zn-Al plating layer were measured by melt | dissolving a plating layer using the test liquid mentioned above and performing ICP emission spectroscopy. The plating adhesion amount of the Zn-Al plating iron wire was computed by the indirect method according to JISH0401. The structure of the plating layer was observed by SEM, and the obtained SEM image was subjected to image processing, and the diameter of the primary tablet was determined as the average particle diameter (circle equivalent diameter) converted into circles. The thickness of the alloy formation layer was observed by TEM and the cross section of the plating layer was measured using EDS together. In addition, the unevenness (fractional interface) at the interface portion between the iron wire and the Zn-Al plating layer was evaluated using a box counting method, and the fractal dimension was determined.

In addition, corrosion loss (corrosion resistance), surface properties, workability, metal mesh properties were evaluated as follows.

The corrosion resistance of the manufactured Zn-Al plated iron wire was evaluated by performing a 1000-hour test by the neutral salt spray test based on JIS Z 2371, and calculating | reducing the corrosion loss (g / m <2>) from the change of the weight before and behind a test. . In addition, when red rust generate | occur | produced after this test, corrosion resistance (corrosion loss) was evaluated as "red rust generation." In addition, in order to satisfy the corrosion resistance requirement of the plated iron wire, this corrosion loss needs to be 300 g / m 2 or less. About workability, using a dry lubricant, the hot-dip Zn-Al plated iron wire was diced (processed) to 80% of reduction ratio, and the peeling rate of the plating of the hot-dip Zn-Al plated iron wire was calculated | required. When this peeling rate is 20% or less, workability was evaluated as "good", and when peeling rate is less than 20%, workability was evaluated as "defect". In addition, when the surface roughness of the plated iron wire was 5 or less random surface roughness parts per 1m in length, and unplating was not confirmed, the surface properties were evaluated as "good". When more than 5 and 10 or less surface roughness parts are confirmed per 1m length, and unplating is not confirmed, the surface property is evaluated as "good", and when more than 10 surface roughness parts are confirmed, or non-plating When this was confirmed, the surface property was evaluated as "defect".

In addition, about the 1st-11th Example and the 12th-16th comparative example which used the steel types A-G of Table 1, the diamond-shaped metal net | network whose mesh size (mesh) is 65 mm was manufactured from the plated iron wire, In addition, the strength of the metal mesh and the uniformity and netting of the mesh shape were comprehensively evaluated. By this evaluation, when the manufactured metal net was excellent, the metal net characteristic was evaluated as "good", and when the manufactured metal net can be used satisfactorily, the metal net characteristic was evaluated as "possible". When it is difficult to use as a metal mesh or when it is difficult to manufacture a metal mesh, the metal mesh characteristic was evaluated as "impossible." The results are shown in Table 3. In addition, the twelfth comparative example is a pure zinc plated iron wire, and the thirteenth comparative example is a Zn-Al plated iron wire manufactured by a two bath method.

In the Zn-Al plated iron wires of the first to eleventh embodiments, the surface properties were good and the corrosion resistance was excellent. In particular, about corrosion resistance, the corrosion loss in the salt spray test was about 1/3 of the pure galvanized iron wire of the 12th comparative example. In addition, the Zn-Al plated iron alloy generating layer (Fe-Al-based alloy generating layer) of the first to eleventh embodiments was made of pure zinc plated iron wire of the twelfth comparative example and Zn-Al plating produced by the two bath method of the thirteenth comparative example. Thinner than iron wire Therefore, in the Zn-Al plated iron wires of the first to eleventh embodiments, the amount of peeling of the plated layer by drawing was small, the workability was good, and the comprehensive evaluation as the metal network was excellent.

On the other hand, in Comparative Example 14, since the amount of Al in the Zn-Al plating layer was small, the corrosion loss increased. In the fifteenth comparative example, since the amount of Al in the Zn-Al plating layer was large, the melting point of the plating layer increased, and non-plating occurred in a part of the plating layer. Therefore, in the 15th comparative example, red rust generate | occur | produces in the part (non-plating part) in which the plating adhesion amount fell in the salt spray test, and workability also deteriorates due to deterioration of surface property, and plating peeling is carried out at the time of drawing processing. Occurred. In the sixteenth comparative example, the passage speed of the iron wire was low, and the time until the water cooling started after the plated iron wire was pulled up from the hot dip bath was long. Therefore, alloying progressed and Fe amount in the plating layer increased. In addition, the alloy generating layer was thickened, the diameter of the primary crystals (primary Al phase or primary Zn phase) was coarsened, and the plating adhesion amount was partially reduced by flowing down of the uncoagulated layer. Therefore, in the 16th comparative example, red rust generate | occur | produced in the salt spray test due to the fall of the partial plating adhesion amount, and the surface property deteriorated by the fall of the uncoagulated layer. In addition, plating cracks and plating peelings occurred at the time of processing by the thick alloy generating layer caused by the deterioration of the surface properties and the increase of Fe in the plating layer. In the fourteenth, seventeenth and eighteenth comparative examples, the fractal dimension of the unevenness of the interface portion between the iron wire and the plating layer was small. Therefore, in the fourteenth, seventeenth and eighteenth comparative examples, the stability of the flux treatment was lowered, non-plating occurred locally, and the surface properties deteriorated. In addition, the corrosion resistance of the plated iron wire was reduced by this local non-plating. In particular, in the seventeenth comparative example, even when the composition of the plating bath was controlled, the amount of Fe in the plating layer increased due to the decrease in the processability of the flux when the plating adhesion amount was secured. Therefore, plating crack and plating peeling generate | occur | produced at the time of processing by the thick alloy formation layer.

Further, in the nineteenth to twenty-second embodiments using the steel types H to K not used as the metal mesh, the amount of Al in the plating layer was 3.0% or more and 15.0% or less, the amount of Fe in the plating layer was 3.0% or less, and the fractal dimension was 1.05. It was also 1.30 or less. Therefore, in the Zn-Al plating iron wire of Example 19-22, the surface property was favorable and was excellent in corrosion resistance.

In the twenty-third comparative example, the fractal dimension was 1.05 or more, but because of the slow passing speed of the iron wire, the alloy generating layer was greatly grown. Therefore, Fe concentration in the plating layer was more than 3.0%. In addition, in this twenty-third comparative example, since the water cooling start time was longer than 3 seconds, the primary Al phase was growing significantly. In the twenty-fourth comparative example, the plated wire was a hard material and the surface adjustment treatment was insufficient, so the fractal dimension was less than 1.05. In addition, in this twenty-fourth comparative example, since the Al concentration of the plating bath was high, the melting point of the molten metal was high, and the primary Al phase was greatly grown. In Comparative Example 25, the passage speed of the iron wire was low, and the primary Al phase was greatly grown. In the twenty-fifth comparative example, a thick scale was produced in the annealing step, and the scale was not completely removed even after pickling, so the flux treatment was not performed normally. Therefore, plating adhesion amount fell and the non-plating generate | occur | produced. In the 26th comparative example, since Al concentration of the plating bath was low, the viscosity of molten metal became high and plating adhesion amount increased. However, in this 26th comparative example, alloying reaction of Fe and the plating metal advanced, and the alloy generating layer grew large.

Next, as a 1st modification, the recessed part (release part) was formed in the surface of the plating layer, and the slip resistance of the obtained plating iron wire was evaluated.

When manufacturing the Zn-Al plated iron wire equivalent to Example 1, the cold roll processing apparatus which has a convex part in the roll surface was arrange | positioned in front of a winding apparatus, and cold worked, and the recessed part was formed in the surface of a molten Zn-Al plated iron wire. . The shape and dimension of the recessed part of the molten Zn-Al plating iron wire surface were controlled by the convex part of the roll surface. As the dimensions of the recess, the depth of the recess, the ratio of the recess depth to the width of the recess (depth / width, recess shape ratio), and the number of recesses per unit area were changed. In addition, the shape of the recess was rectangular.

About the dimension of the recessed part of the surface of a Zn-Al plated iron wire, the cross section perpendicular | vertical to the longitudinal direction of a Zn-Al plated iron wire is cut and polished, this cross section is observed using SEM, and it is recessed by the measuring function provided in SEM. The depth and width of the section was measured. In addition, about the number of recessed parts of the surface of a Zn-Al-plated iron wire, after apply | coating paint to the surface of the hot-dip galvanized wire cut | disconnected to 100 mm length, it transfers to paper and judges the part in which the paint is not transferred as a recessed part. The number of recesses per cm 2 was determined by image analysis.

Slip resistance by the formation of recesses on the Zn-Al plating surface was evaluated as follows. From the Zn-Al plated iron wire, a rhombic metal mesh having a mesh size of 65 mm, a length of 500 mm and a width of 500 mm was removed, and the metal mesh was fixed on a horizontal pedestal to wet the surface of the metal mesh by spraying. Thereafter, a rubber piece weighing 4 kg was placed on a fixed metal mesh, the rubber piece in a stationary state was pulled in the horizontal direction, and the load (maximum value of the tensile load) when the rubber piece started to move was measured. The static friction coefficient was calculated | required by dividing the maximum value of this tensile load by the weight of a rubber piece.

The measurement was repeated 6 times with respect to one metal mesh, and the slip resistance was evaluated as "good" when the average value of the measured static friction coefficient was 0.7 or more. When the average value of the measured static friction coefficient was less than 0.7, slip resistance was evaluated as "possible". In addition, the corrosion resistance (corrosion loss) of the Zn-Al plated iron wire was evaluated by the salt spray test in the same manner as in the first example. The results are shown in Table 4.

The Zn-Al plated iron wires of the twenty-seventh to thirty-second embodiments had better slip resistance than the Zn-Al plated iron wires of the thirty-third to thirty-third embodiments. Therefore, in the Zn-Al-plated iron wires of the twenty-seventh to thirty-second embodiments, a more slippery metal net could be manufactured. Moreover, the Zn-Al plated iron wire of Examples 27-35 had the outstanding corrosion resistance and workability. That is, the depth of the recessed part formed in the surface of Zn-Al plated iron wire was sufficient for the Zn-Al plated iron wire of Example 27-32 Example. The Zn-Al plated iron wires of the twenty-seventh to thirty-second embodiments had a sufficient number of concave portions on the surface, as compared with the Zn-Al plated iron wire of the thirty-fourth embodiment. The Zn-Al plated iron wires of the twenty-seventh to thirty-second embodiments had a ratio of the depth of the concave portion provided on the surface of the Zn-Al plated iron wire to the width of the concave portion, as compared with the Zn-An plated iron wire of the twenty-ninth embodiment. In addition, since the ratio of the depth of a recess and the width of a recess is set suitably compared with the Zn-Al plated iron wire of Example 27-32, the apparent specific surface area increases significantly, There was no work and no increase in corrosion loss was seen.

In addition, as a 2nd modification, except having added Si in a molten Zn-Al plating bath, the Zn-Al plating iron wire containing Si in a plating layer using the method similar to the 1st-11th Example shown in Table 3 using the same method Was produced and Zn-Al plating iron wire was evaluated. In addition, Al amount and Si amount in this molten Zn-Al plating bath are adjusted suitably.

For the prepared Zn-Al plated iron wire, Al concentration, Si concentration and Fe concentration of the Zn-Al plating layer, the diameter of the primary crystal (primary Al phase or primary Zn phase) of the Zn-Al-based alloy layer, the thickness of the alloy generating layer, The amount of plating adhesion, the fracturing dimension of the interface between the base iron (coated iron wire) and the plating layer were evaluated. This measurement result is shown in Table 5 with water cooling start time. In addition, the thickness of an alloy formation layer is the thickness of the Fe-Zn type alloy formation layer in pure zinc plating iron wire, and the thickness of the Fe-Al type alloy formation layer in Zn-Al plating iron wire.

In Examples 37 to 47, the amount of Al in the plating layer was 3.0% or more and 15.0% or less, the amount of Si in the plating layer was 0.05% or more and 2.0% or less, the amount of Fe in the plating layer was 3.0% or less, and the fractal dimension was 1.05 or more. It was 1.30% or less. In the 37th to 47th examples, the diameter of the primary tablet (primary Al phase or primary Zn phase) was 10 µm or less, the thickness of the alloy generating layer was 5 µm or less, and the plating deposition amount was 100 g / m 2 or more and 400 g. / M 2 or less. On the other hand, in the 50th to 53rd and 55th comparative examples, the amount of Fe in the plating layer was more than 3.0%. In the comparative examples, in the 50th to 53rd and 55th comparative examples, a thick alloy generating layer exceeding 5 µm was formed. In Comparative Example 50, since a hot dip galvanizing bath containing no Al and Si was used, a Fe-Al-based alloy generating layer was not formed at the interface between the plating layer and the iron wire, and the alloying reaction of Fe and Zn proceeded to a thicker thickness. A Fe—Zn based alloy generating layer was formed. In Comparative Example 51, alloy plating was performed using the two bath method, so that a thick Fe-Al-based alloy generating layer remained. In the 52nd comparative example, since the fractal dimension was small and the amount of Si in the alloy plating was small, it was difficult to control the alloying reaction and the alloy generating layer was growing significantly. In the 55th comparative example, since the passage speed of an iron wire was slow and the time after which a plated iron wire was pulled up out of the plating bath and water-cooling was long, the alloy generation layer was growing large. In addition, in the 50th comparative example, since Al is not contained in the plating bath, the Al rich phase is not formed. In the 53rd comparative example, since the amount of Al in the plating bath was small, the primary crystal could not be confirmed clearly. In Comparative Example 54, since the amount of Al in the plating bath was large, each primary Al phase could not be clearly distinguished. Therefore, in the 53rd and 54th comparative examples, the diameter of the primary tablet could not be measured. In the 55th comparative example, since the time to water cooling start was long, the primary Al phase was coarse.

In the 48th Example, the amount of Si in the plating layer was more than 2.0%, and in the 49th Example, the amount of Si in the plating layer was less than 0.05%.

In addition, the Al concentration, Si concentration and Fe concentration of the Zn-Al plating layer described above, the initial diameter of the Zn-Al alloy layer, the thickness of the alloy formation layer, the plating adhesion amount, the fracturing of the interface between the ground iron (coated iron wire) and the plating layer. The dimensions were evaluated as follows.

The Al concentration, Si concentration, and Fe concentration of the Zn-Al plating layer were measured by dissolving the plating layer using the test solution described above and performing ICP emission spectroscopic analysis. In order to evaluate the thickness of the alloy generating layer and the structure of the plated layer, after cross-section of the plated wire was polished, five or more fields were observed at 1000 to 30000 times using field emission scanning electron microscope (FESEM) and EDS. The structure of the plating layer was evaluated by image processing, and the thickness of the alloy generating layer was evaluated by an average value of measuring 10 points using the side function of the microscope (FESEM) of the plating layer structure. According to JIS H 0401, the plating adhesion amount was calculated by the indirect method. The structure of plating was observed by SEM, and the SEM image obtained was image-processed, and the diameter of a primitive was calculated | required as the average particle diameter (circle equivalent diameter) converted into circles. The thickness of the alloy formation layer was observed by TEM and the cross section of the plating layer was measured using EDS together. In addition, the unevenness (fractional interface) at the interface portion between the iron wire and the Zn-Al plating layer was evaluated using a box counting method, and the fractal dimension was determined.

In addition, corrosion loss (corrosion resistance), surface properties, workability, metal mesh properties were evaluated as follows.

The corrosion resistance of the manufactured Zn-Al plated iron wire was evaluated by performing a 1000-hour test by the neutral salt spray test based on JIS Z 2371, and calculating | reducing the corrosion loss (g / m <2>) from the change of the weight before and behind a test. . In addition, when red rust generate | occur | produced after this test, corrosion resistance (corrosion loss) was evaluated as "red rust generation." About workability, using a dry lubricant, the hot-dip Zn-Al plated iron wire was diced (processed) to 80% of reduction ratio, and the peeling rate of the plating of the hot-dip Zn-Al plated iron wire was calculated | required. When this peeling rate is 20% or less, workability was evaluated as "good", and when peeling rate is less than 20%, workability was evaluated as "defect".

Moreover, when the surface roughness of Zn-Al plated iron wire was 5 or less of random surface roughness parts per 1m in length, and unplating was not confirmed, the surface property was evaluated as "good". When more than 5 and 10 or less surface roughness parts are confirmed per 1m length, and unplating is not confirmed, the surface property is evaluated as "good", and when more than 10 surface roughness parts are confirmed, or non-plating In this case, the surface properties were evaluated as "poor". In addition, a rhombic metal mesh having a mesh size of 65 mm was manufactured from the plated iron wire, and the strength and uniformity and meshability of the mesh were evaluated comprehensively. According to this evaluation, when the manufactured metal net was excellent, the metal net characteristic was evaluated as "good", and when the manufactured metal net can be used satisfactorily, the metal net characteristic was evaluated as "possible". When it is difficult to use as a metal mesh or when it is difficult to manufacture a metal mesh, the metal mesh characteristic was evaluated as "impossible."

These results are shown in Table 6. The comparative example 50 is a pure zinc plated iron wire, and the comparative example 51 is a Zn-Al plated iron wire manufactured by a two bath method.

In the Zn-Al plated iron wires of Examples 37 to 49, the surface properties were good and the corrosion resistance was excellent. In particular, about corrosion resistance, the corrosion loss in the salt spray test was about 1/3 of the pure galvanized iron wire of the 50th comparative example. The alloy generating layer (Fe-Al-based alloy generating layer) of the Zn-Al plated iron wires of Examples 37 to 49 was prepared by pure zinc plated iron wire of Comparative Example 50 and Zn-Al manufactured by two bath methods of Comparative Example 51. It was thin compared to the plated iron wire. Therefore, in the Zn-Al plated iron wire of Examples 37-49, there was little peeling amount of the plating layer by wire drawing, was excellent in workability, and was excellent in comprehensive evaluation as a metal network. On the other hand, in the 52nd comparative example, since the fractal dimension was small and the amount of Si of the Zn-Al plating layer was small, the plating processability became nonuniform, a locally thick alloy generating layer was formed, and the thickness of the alloy generating layer became nonuniform. Therefore, plating adhesiveness fell locally, surface property deteriorated, and workability fell. In Comparative Example 53, since the Al concentration in the Zn-Al plating layer was low, the corrosion resistance deteriorated. In the 54th comparative example, since the amount of Al in the Zn-Al plating layer was large, the melting point of the plating layer increased, and non-plating occurred in a part of the plating layer. Therefore, in the 54th comparative example, red rust generate | occur | produces in the part (non-plating part) in which the plating adhesion amount fell in the salt spray test, and workability also deteriorates due to deterioration of surface property, and plating peeling occurs at the time of drawing process. It was.

In Comparative Example 55, the passage speed of the iron wire was low, and the time until the start of the water cooling was long after the plated iron wire was pulled up from the hot dip bath. Therefore, alloying progressed and Fe amount in the plating layer increased. In addition, the alloy generating layer became thick, the diameter of the primary Al phase was coarsened, and the amount of plating adhesion was partially reduced by flowing down the uncoagulated layer. Therefore, in the 55th comparative example, red rust generate | occur | produced in the salt spray test due to the fall of the partial plating adhesion amount, and the surface property deteriorated by the fall of the uncoagulated layer. In addition, plating cracks and plating peelings occurred at the time of processing by the thick alloy generating layer caused by the deterioration of the surface properties and the increase of Fe in the plating layer.

In addition, in Example 38, since the amount of Si in a plating layer is 0.05% or more and 2.0% or less, the structure | tissue and hardness of an alloy generation layer are controlled suitably. Therefore, compared with the 48th example whose Si content in a plating layer is more than 2.0%, the hardness of the alloy production layer was optimized, and workability and metal mesh characteristics improved. In addition, the structure (particularly the thickness) of the alloy generating layer was controlled appropriately compared to the forty-ninth embodiment in which the amount of Si in the plating layer was less than 0.05%, thereby improving workability and metal mesh properties.

In addition, as a 3rd modification, the recessed part (release part) was formed in the surface of the plating layer of a 3rd modification, and the slip resistance of the plated iron wire obtained was evaluated.

When manufacturing the Zn-Al plated iron wire equivalent to Example 37, the cold 3-roll processing apparatus which has a convex part in a roll surface is cold-processed by arrange | positioning in front of a winding apparatus, and a recess is formed in the surface of a molten Zn-Al plated iron wire. It was. The shape and dimension of the recessed part of the molten Zn-Al plating iron wire surface were controlled by the convex part of the roll surface. As the dimension of the recess, the depth of the recess, the ratio (depth / width) of the recess depth to the width of the recess, and the number of recesses per unit area were changed. In addition, the shape of the recess was rectangular.

About the dimension of the recessed part of the surface of a Zn-Al plated iron wire, the cross section perpendicular | vertical to the longitudinal direction of a Zn-Al plated iron wire is cut and polished, this cross section is observed using SEM, and it is recessed by the measuring function provided in SEM. The depth and width of the section was measured. In addition, about the number of recessed parts of the surface of a Zn-Al-plated iron wire, after apply | coating paint to the surface of the hot-dip galvanized wire cut | disconnected to 100 mm length, it transfers to paper and judges the part in which the paint is not transferred as a recessed part. The number of recessed parts per cm <2> was calculated | required by image analysis.

Slip resistance by formation of the recessed part in the plating surface was evaluated as follows. From the Zn-Al-plated iron wire, a mesh of 65 mm in length, 500 mm in length, and 500 mm in width was removed, and the metal mesh was fixed on a horizontal pedestal to wet the surface of the metal mesh by spraying. Thereafter, a rubber piece having a weight of 4 kg was loaded on the fixed metal net, the rubber piece in the stationary state was pulled in the horizontal direction, and the load (maximum value of the tensile load) when the rubber piece began to move was measured. The static friction coefficient was calculated | required by dividing the maximum value of this tensile load by the weight of a rubber piece. The measurement was repeated 6 times with respect to one metal mesh, and the slip resistance was evaluated as "good" when the average value of the measured static friction coefficient was 0.7 or more. When the average value of the measured static friction coefficient was less than 0.7, slip resistance was evaluated as "possible". In addition, the corrosion resistance (corrosion-loss) of Zn-Al plated iron wire was evaluated by the salt spray test similarly to Example 37. The results are shown in Table 7.

The Zn-Al plated iron wires of the 56th to 61st Examples had better slip resistance than the Zn-Al plated iron wires of the 62nd to 64th Examples. Therefore, in the Zn-Al plated iron wires of the fifty-fifth to sixty-first embodiments, a more slippery metal net could be obtained. Moreover, the Zn-Al plated iron wire of Examples 56-64 had the outstanding corrosion resistance. Moreover, the depth of the recessed part formed in the surface of Zn-Al plated iron wire was sufficient for the Zn-Al plated iron wire of Example 56-61 Example compared with the Zn-Al plated iron wire of Example 62. In the Zn-Al plated iron wires of Examples 56-61, the number of concave portions on the surface was sufficient as compared with the Zn-Al plated iron wire of Example 63. Moreover, the ratio of the depth of the recessed part formed in the surface of the Zn-Al plated iron wire and the width | variety of the recessed part in the Zn-Al plated iron wire of Example 56-61 Example was sufficient compared with the Zn-Al plated iron wire of Example 64. In addition, since the ratio of the depth of a recessed part and the width | variety of a recessed part is set suitably compared with the Zn-Al plated iron wire of Example 56-61 Example 65, the apparent specific surface area increases largely. There was no increase in corrosion loss.

According to the present invention, the corrosion resistance and workability of Zn-Al plated iron wire can be improved. In particular, when a Zn-Al plated iron wire having a low C iron wire as a base metal is used as the metal network, durability and lifespan are greatly improved, and the Zn-Al plated iron wire can be more complicatedly processed. In addition, by forming a recess in the surface of the Zn-Al plated iron wire after hot-dip plating, slip resistance is improved, and workability of laying a metal net is improved. Therefore, the present invention has a very high industrial applicability.

Claims (15)

Iron Wire,
Zn-Al plating layer formed on the surface of the iron wire,
The Zn-Al plating layer contains, in mass%, 3.0% or more and 15.0% or less of Al, 0.01% or more and 3.0% or less of Fe, and the balance includes Zn and unavoidable impurities,
Fractal dimension of the interface between the iron wire and the Zn-Al plating layer measured by the box counting method is 1.05 or more,
The Zn-Al plating layer includes a Zn-Al alloy layer and a Fe—Al-based alloy generating layer between the iron wire and the Zn-Al alloy layer,
The diameter of the primary crystal of the Zn-Al alloy layer is limited to 10 μm or less,
Zn-Al plating iron wire, characterized in that to limit the thickness of the Fe-Al alloy generating layer to 5㎛ or less. The Zn-Al plated iron wire according to claim 1, wherein the Zn-Al plated layer contains 6.0% or more and 15.0% or less of Al by mass%. The Zn-Al plated iron wire according to claim 1 or 2, wherein the Zn-Al plated layer contains 0.01% or more and 3.0% or less Si in mass%. The said iron wire is mass% of Claim 1 or 2,
0.01% or more and 0.70% or less of C,
0.1% or more and 1.0% or less of Si,
A Zn-Al plated iron wire, wherein the Zn-Al plated iron wire contains 0.1% or more and 1.5% or less of Mn, and the balance contains Fe and inevitable impurities, and includes ferrite. The Zn-Al plating according to claim 4, wherein the iron wire further contains, by mass%, at least one element selected from 0.1% or less of Al, 0.1% or less of Ti, and 0.0070% or less of B. Iron wire. The Zn-Al plated iron wire according to claim 1 or 2, wherein the plating adhesion amount of the Zn-Al plating layer is 100 g / m 2 or more and 400 g / m 2 or less. Iron Wire,
Zn-Al plating layer formed on the surface of the iron wire,
The Zn-Al plating layer contains, in mass%, 3.0% or more and 15.0% or less of Al, 0.01% or more and 3.0% or less of Fe, and the balance includes Zn and unavoidable impurities,
Fractal dimension of the interface between the iron wire and the Zn-Al plating layer measured by the box counting method is 1.05 or more,
On the surface of the Zn-Al plating layer, recesses are formed at a density of 2 or more and 100 or less per 1 cm 2, and the recesses are 0.2 mm or more and 0.5 mm or less in depth and 0.1 or more and 3 or less in width. Zn-Al plated iron wire, characterized in that it has a ratio of the depth. After the wire is wire-processed, it is pickled and subjected to surface adjustment treatment so that the fractil dimension of the surface of the iron wire measured by the box counting method is 1.05 or more, passed through the flux of the aqueous solution containing chloride, and after drying, A method for producing a Zn-Al plated iron wire, characterized in that it is immersed in a molten Zn-Al bath containing 3.0% or more and 15.0% or less of Al by mass, and water-cooled within 3 seconds. The method for producing a Zn-Al plated iron wire according to claim 8, wherein the molten Zn-Al bath contains Al in an amount of 6.0% or more and 15.0% or less by mass%. The method for producing a Zn-Al plated iron wire according to claim 8 or 9, wherein the molten Zn-Al bath contains Si in an amount of 0.01% or more and 3.0% or less in mass%. The said iron wire is mass%, 0.01% or more and 0.70% or less of C, 0.1% or more, 1.0% or less of Si, 0.1% or more, and 1.5% or less of Mn. A method for producing a Zn-Al plated iron wire, wherein the remaining portion contains Fe and an unavoidable impurity, and has a structure containing ferrite. The method according to claim 8 or 9, wherein after the iron wire is immersed in a molten Zn-Al bath and pulled up, and before water cooling, the plating adhesion amount is adjusted so that the plating adhesion amount is 100 g / m 2 or more and 400 g / m 2 or less. The manufacturing method of Zn-Al plating iron wire characterized by the above-mentioned. After the wire is wire-drawn, it is pickled and subjected to a surface adjustment treatment so that the fractal dimension of the surface of the wire measured by the box counting method is 1.05 or more, passed through in a flux, and after drying, 3.0% in mass%. The above is further immersed in a molten Zn-Al bath containing 15.0% or less of Al, followed by water cooling within 3 seconds,
A method for producing a Zn-Al plated iron wire, wherein a recess is formed on the surface of the Zn-Al plated layer by water or laser processing after cooling with water. The method of claim 13, wherein the recess has a depth of 0.2 mm or more and 0.5 mm or less and a ratio of the depth to the width of 0.1 or more and 3 or less, and two or more per 100 cm 2 surface area of the Zn-Al plating layer. A method for producing a Zn-Al plated iron wire, characterized in that it is formed at a density of less than or equal to two pieces. delete

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