KR20030037249A - Galvanized, Zn-Al alloy and Zn-Al-Mg-Si alloy galvanized mild and hard-drawn steel wire with high adhesive, strength and formability and its production method - Google Patents

Abstract

PURPOSE: Hot dip coated iron wire and steel wire whose coating layer is improved in adhesion, strength and formability by adding a trace of nucleation promoting elements to existing hot dip Zn, Zn-Al alloy and Zn-Al-Mg-Si alloy coating constituents, and manufacturing methods thereof are provided. CONSTITUTION: The hot dip coated iron wire is characterized in that eutectic structure in which fine cubic grains are uniformly formed is obtained to increase strength of coating layer and improve adhesion and formability of the coating layer by adding a trace of one or more nucleation promoting elements of Sc, Y, Zr, Hf and Er to existing hot dip Zn, Zn-Al alloy and Zn-Al-Mg-Si alloy coating constituents, thereby promoting nucleation during solidification of a hot dip coating solution. The hot dip coated steel wire is characterized in that eutectic structure in which fine cubic grains are uniformly formed is obtained to increase strength of coating layer and improve adhesion and formability of the coating layer by adding a trace of one or more nucleation promoting elements of Sc, Y, Zr, Hf and Er to existing hot dip Zn, Zn-Al alloy and Zn-Al-Mg-Si alloy coating constituents, thereby promoting nucleation during solidification of a hot dip coating solution. The hot dip Zn, Zn-Al alloy and Zn-Al-Mg-Si alloy coated iron wire comprises 0.01 to 1.0 wt.% of Sc, 0.01 to 1.0 wt.% of Y, 0.01 to 1.0 wt.% of Zr, 0.01 to 1.0 wt.% of Hf and 0.01 to 1.0 wt.% of Er as nucleation promoting elements. The hot dip Zn, Zn-Al alloy and Zn-Al-Mg-Si alloy coated steel wire comprises 0.01 to 1.0 wt.% of Sc, 0.01 to 1.0 wt.% of Y, 0.01 to 1.0 wt.% of Zr, 0.01 to 1.0 wt.% of Hf and 0.01 to 1.0 wt.% of Er as nucleation promoting elements.

Description

Galvanized, Zn-Al alloy and Zn-Al-Mg-Si alloy galvanized mild and hot-dip galvanized, zinc-aluminum alloy and zinc-aluminium-magnesium-silicon alloy plated wire and steel wire with excellent adhesion, strength and workability hard-drawn steel wire with high adhesive, strength and formability and its production method}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot-dip galvanized steel wire and steel wire having excellent adhesion, high strength, and abundant workability, which are used in gabions, fences, fishing nets, support wires of overhead wires, etc., which are installed in outdoor exposed places. Hot-dip galvanized wire and steel wire is divided into hot-dip galvanized wire and steel wire and hot-dip galvanized aluminum and Zn-Al-Mg-Si-based alloy plated wire and steel wire. Here, the description will focus on hot-dip zinc-aluminum alloy plated iron wire and steel wire having excellent corrosion resistance.

Molten zinc-aluminum alloy plated iron wires and steel wires are generally subjected to flux treatment after the base metal is cleaned and cleaned by a degreasing step. Hot-dip plating is performed by zinc-based hot dip plating, followed by a two-step manufacturing process in which Zn- (4-10wt.%) Al alloy bath is finally hot-dipped and Zn- (4-10wt.%) Al. It is divided into a one-step manufacturing process that is finished by one hot-dip plating in an alloy bath.

Hot-dip zinc-aluminum alloy plated wires and steel wires have satisfactory corrosion resistance, but in practical use, if the plated layer is damaged by a strong impact from the outside and is lost, it can provide fatal defects throughout the installation, no matter how local. For example, in applications such as gabions, not only the corrosion resistance of the plating layer but also the adhesion between the plating layer and the base metal, the hardness and workability of the plating layer itself should be considered as important factors. This is because, in practical use, much damage to the plated steel wire is inevitable. Therefore, in order to increase the resistance due to external impact, there are two methods of increasing the thickness of the plating layer and methodically increasing the thickness of the plating layer.

First, the same method as the former may transfer the steel wire and the steel wire in the plating bath while rapidly depositing it, thereby increasing the viscosity with the molten plating liquid to increase the amount of the molten plating liquid attached to the steel wire. However, this method has a tendency to form irregular plating thickness in the vertically vertical cross section of the plated wire and the steel wire due to the fast flux, and there is a limitation in the plating equipment.

As a result, it is judged that sufficient plating layer thickness cannot be secured with the current hot dip plating equipment. On the other hand, some of the Zn-Al-Mg ternary alloy plating component added Mg has been proposed, but as a result of the formation of a thin plated layer was found to improve the corrosion resistance to some extent, but generally required thick for gabions, etc. When applied to the iron wire and steel wire of the plating layer, cracks occurred in the plating layer. In order to solve the above problems, various studies have been conducted. However, if the thickness of the plating layer is increased, the layer of the Fe-Zn intermetallic compound, which is a reaction product at the interface, may be thickened to overcome defects such as cracking or peeling of the plating layer. No,

As mentioned above, in case of being used for the purpose of practically causing a lot of damage to the plated wire and steel wire, in order to prevent the metal from being exposed to the corrosive environment and rapidly corroding due to local damage of the plated layer, One should choose one of the methods to thicken the thickness or to give or strengthen the characteristics required to increase the resistance to damage to the plating layer itself.

In the case of ①, as described above, when the thickness of the plating layer is thickened, a crack or peeling phenomenon occurs in the plating layer, or Fe is a reaction product formed at the interface of the base metal because it remains in the plating bath for a relatively long time during the hot dip plating process. As the layer of -Zn intermetallic compound becomes thick, the brittleness increases and the ductility decreases, resulting in product defects such as cracking or peeling of the plating layer during manufacture or use.

Therefore, it is an effective alternative to give or strengthen the properties required to increase the resistance to damage, such as ②. Therefore, it is necessary to increase the strength of the plating layer itself, and to have adhesiveness and workability that are practically not problematic.

The method of increasing the plating layer itself strength, adhesiveness and workability in the hot-dip plating method is possible by changing the coarse columnar crystal grain process structure, which is the solidification structure of the plated layer obtained in the hot dip plating process, into a fine isotropic crystal grain process structure. The more uniform and fine isotropic the grain size is, the more effective it is. Isotropic grain microstructure is very effective in securing excellent adhesion, strength and processability, and the finer the structure, the more optimal characteristics are obtained. Such microstructures can be achieved by controlling the nucleation of solid phases so that fine grains can be grown uniformly when the liquid phase solidifies metallurgically. That is, the solid phase nucleation behavior can be controlled by adding nucleation promoting elements.

Therefore, in the present invention, when the solidification of the plating layer by adding a small amount of additive elements that promote nucleation in molten zinc, zinc-aluminum alloy and Zn-Al-Mg-Si-based alloy plating alone or in combination, the nucleation sites The purpose is to obtain a fine and uniform process structure of the crystal grains.

The present invention is a process for uniformly forming fine isotropic crystal grains by adding a small amount of nucleation promoting elements to the existing molten zinc, zinc-aluminum alloy and Zn-Al-Mg-Si-based alloy plating components in view of the above problems The structure is obtained, thereby providing a hot-dip iron wire and steel wire, and a method for producing the same, which improve the adhesion, strength, and workability of the plating layer.

In order to achieve the above objectives in conventional hot dip galvanizing (GI based) and zinc-aluminum alloy (Galfan based, Galvalume based) and Zn-Al-Mg-Si based alloy plating components, Sc: 0.01-1.0%, Y: 0.01-1.0%, Zr: 0.01-1.0%, Hf: 0.01-1.0%, Er: 0.01-1.0%, It is characterized by adding individually or in combination. When the above added elements are added alone or in combination in small amounts, the nucleation is promoted upon solidification of the molten plating solution, thereby miniaturizing the coagulation cell structure, and finally obtaining a uniform and fine grain process structure. From this, the adhesiveness, strength, and workability of the plating layer can be improved.

The components of the added elements Sc, Y, Zr, Hf, and Er are all 0.01 to 1.0%, and when the elements are added at 1.0% or more, the reactivity with Fe element, which is a metal component, or Zn, Al, and Mg, a plating component, is added. This sharp increase increases the formation of a brittle intermetallic compound which reacts with the base metal component and the plating component and thus adversely affects the plating layer. In addition, when less than 0.01% is added, the effect cannot be expected.

Based on the above, the hardness values and the winding test results of the specimens prepared by the specific examples of the present invention are summarized in Table 1 and Table 2, respectively.

Sample Nos. 1 to 8 shown in Table 1 are alloy plating components proposed in the present invention, and Nos. 9 to 14 are conventionally known as comparative materials. In other words, a molten plating solution is prepared by adding appropriate amounts of the nucleation-promoting elements Sc, Y, Zr, Hf, and Er, alone or in combination, to various existing hot-dip plating components in any combination of at least 0.01% to 1.0%. And the steel wires were plated by a conventional method, and then the hardness characteristics of the plated layers were examined. At this time, the plating layer was uniformly prepared to maintain the thickness of about 20㎛ in all conditions. The hardness test piece was prepared by mirror-processing the cross section of the plated steel wire, and measured using a micro vickers. Hardness measurement was mainly performed 5 times in the region of the zeta phase area where coagulation tissue is well developed to remove the highest value and the lowest value, and was determined as the average value of the remaining measurements.

As can be seen from Table 1, it can be seen that the invention material shows a very high hardness characteristics compared to the conventional comparative material. When the added element was added up to 1.0%, hardness value of about 280Hv was obtained, which showed a hardness increase of about 50% compared with the general hardness value of the existing comparative material. In addition, as a result of examining the microstructure, the process material of fine isotropic crystal grains was observed in the invention material, but the coarse columnar dendrite structure was observed in the comparative material. In other words, it can be said that the difference in hardness characteristics of the invention and the comparative material is due to the difference in the solidification structure. That is, as a small amount of the additive element promoting the nucleation, which is the proposal of the present invention, these elements act as nucleation sites during the solidification of the plating solution to promote nucleation, resulting in a fine grain structure. It is believed that this contributed to the increase in hardness value.

As such, when the hardness was increased, a representative winding test was conducted to investigate changes in adhesion and workability, and the results are summarized in Table 2. In the winding test, the steel wire plated on the wire rod having the same diameter as the test piece was wound 8 times, and then peeling or cracking occurred in the plated layer was examined. Inventive material with high hardness was found to be very good in cracking and peeling characteristics compared with the conventional comparative materials. Therefore, the fine process structure obtained from the inventive material is considered to contribute greatly to the improvement of adhesion and workability of the plating layer as well as the hardness characteristic.

Therefore, the alloy plating component of the present invention was greatly effective not only in the strength of the plating layer itself but also in improving adhesion and workability.

As can be seen from the test results as described above, by controlling the microstructure of the plating layer, it is possible to manufacture a plated iron wire and steel wire having high adhesion and workability while having high strength of the plating layer. As mentioned in the necessity of the present invention, such plated wires and steel wires are very suitable for applications in which the plated layer may be damaged due to external force or impact in practical use, and may also prevent damage accidents that may arise from inadvertent construction. have. In particular, since the primary purpose of the hot-dip iron and steel wire is to prevent the corrosion of the base metal from the corrosive environment, the stability and reliability of the plating layer will determine the performance of the entire installation. Therefore, the improvement of the characteristics of the plating layer itself is connected to the improvement of the performance of the entire facility, it can be said that it is very important to improve the quality of the product, improve the reliability, and prevent unexpected safety accidents.

In addition, although the present invention relates to steel wires and steel wires, it is a technology that can be suitably applied to pipes, steel sheets and other structures, and therefore a large ripple effect is expected in the entire industry.

Claims (5)

Nucleus upon solidification of the molten plating solution by adding a small amount of Sc, Y, Zr, Hf, Er, which are nucleation promoting elements, alone or in combination to the conventional molten zinc, zinc-aluminum alloy and Zn-Al-Mg-Si alloy plating components. Promotes formation to obtain a process structure in which isotropic fine grains are uniformly formed, thereby increasing the strength of the plated layer and improving the adhesion and workability. Nucleus upon solidification of the molten plating solution by adding a small amount of Sc, Y, Zr, Hf, Er, which are nucleation promoting elements, alone or in combination to the conventional molten zinc, zinc-aluminum alloy and Zn-Al-Mg-Si alloy plating components. Promotes formation to obtain a process structure in which isotropic fine grains are uniformly formed, thereby increasing the strength of the plating layer and improving the adhesion and workability. The method according to claim 1, as a nucleation promoting element, in weight percent, Sc: 0.01-1.0%, Y: 0.01-1.0%, Zr: 0.01-1.0%, Hf: 0.01-1.0%, Er: 0.01-1.0% Hot-dip zinc, zinc-aluminum alloy and Zn-Al-Mg-Si alloy plating iron wire, containing The method according to claim 1, as a nucleation promoting element, in weight percent, Sc: 0.01-1.0%, Y: 0.01-1.0%, Zr: 0.01-1.0%, Hf: 0.01-1.0%, Er: 0.01-1.0% Hot-dip zinc, zinc-aluminum alloy and Zn-Al-Mg-Si alloy plating steel wire, containing The steel sheet, pipes and other structures of claim 1 using the proposed hot-dip alloy composition and its manufacturing mechanism.