KR101543913B1 - Apparatus for alloy plated steel sheet having excellent surface appearance and method for the same - Google Patents

Abstract

The present invention provides a method of manufacturing a zinc-aluminum-magnesium alloy coated steel sheet which has a complex pickling process before and after a conventional pickling process to provide a pickling equipment shortening effect and surface characteristics such as surface appearance and gloss. In the present invention, the surface scale layer is removed by the Abrasive Brushing process before the pickling process, the acidity is increased, the pickling process is shortened, the polishing brushing process is connected to the end of the pickling process, The scale removal and the surface roughness of the steel sheet can be selectively and suitably controlled to secure the surface appearance and the plating adhesion.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing an alloy-coated steel sheet having excellent surface appearance,

More particularly, the present invention relates to an apparatus for manufacturing a zinc-aluminum-magnesium alloy coated steel sheet having excellent surface appearance and a manufacturing method using the same.

The zinc plating method is a technique for improving the corrosion resistance of a steel sheet in which zinc having a lower corrosion potential than iron is attached to the steel sheet. It is widely used to produce steels with high corrosion resistance and excellent corrosion resistance and economical efficiency by inducing corrosion of zinc faster than iron in an oxidizing atmosphere to suppress corrosion of iron. Particularly, the hot-dip galvanized steel sheet which forms the plating layer by immersing the steel into the molten zinc has a simpler manufacturing process than the galvanized steel sheet and has a low product price, and thus is widely used in the fields of building materials, household appliances, The demand is increasing.

A more detailed explanation of the corrosion mechanism of the zinc plating material is that the zinc-plated hot-dip galvanized steel sheet is subjected to a sacrificial corrosion method in which zinc, which is lower in redox potential than iron is firstly corroded, Protection is also provided. In addition, zinc in the plating layer is oxidized to form a dense corrosion product on the surface of the steel sheet, thereby improving the corrosion resistance of the steel sheet by blocking the steel from the oxidizing atmosphere. However, the increase in the air pollution and deterioration of the corrosive environment due to the industrial advancement are increasing, and due to the strict regulations on the resource and energy saving, there is a growing need for the development of steels having better corrosion resistance than the conventional zinc plated steel sheets.

In addition, due to the rise in zinc prices, the demand of the industry to increase the corrosion resistance while reducing the amount of zinc used as the plating material is steadily increasing. Recently, studies on zinc (Zn) - aluminum (Al) - magnesium (Mg) alloy coated steel sheets which improve the corrosion resistance of steel by adding elements such as aluminum (Al) and magnesium (Mg) .

The zinc-zinc-aluminum (Al) -magnesium (Mg) alloy coated steel sheet is very corrosion-resistant and can be used in exterior materials for buildings and home appliances. If the surface roughness is very good and the appearance is good, have. In addition, the zinc (Zn) -aluminum (Al) -magnesium (Mg) alloy plating solution has a weaker interaction property with the base steel sheet than the conventional hot zinc plating solution,

An object of the present invention is to provide an apparatus for manufacturing a zinc-aluminum-magnesium alloy coated steel sheet having excellent surface appearance and excellent plating adhesion.

The present invention also provides a method for producing a zinc-aluminum-magnesium alloy coated steel sheet having excellent surface appearance and excellent plating adhesion.

The present invention relates to an apparatus for manufacturing an alloy-plated steel sheet including an acid detail for pickling hot-rolled steel sheet, wherein a first polishing unit and a second polishing unit are respectively provided at the front end and the rear end of the mountain detail, Wherein the pickling section is configured to pickle the hot-rolled steel sheet subjected to the primary polishing brush treatment in the first polishing section, and the second polishing section is configured to pick-pick the hot- And the primary polishing brush treatment, the pickling treatment, and the secondary polishing brush treatment are sequentially and successively performed on the surface of the steel sheet subjected to the secondary polishing brush treatment, and the primary polishing brush treatment, .

Preferably, two or three pairs of polishing brushes are arranged in series at the upper and lower ends of the first polishing portion, and the surface roughness of the polishing brush is 200 to 300 in mesh number.

Preferably, two to eight pairs of polishing brushes are arranged in series at the upper and lower ends of the second polishing portion, and the surface roughness of the polishing brush is 400 to 1200 in mesh number.

Preferably, the pickling portion comprises 2 to 3 pickling baths, and the acid pickling solution of the acid production contains 15 to 20% of hydrochloric acid and maintains a temperature of 65 to 90 ° C.

The present invention also provides a method of manufacturing a hot-rolled steel sheet, Crushing a scale formed on a surface of the hot-rolled steel sheet; Subjecting the surface of the hot-rolled steel sheet to a primary polishing brush treatment; Pickling the hot-rolled steel sheet subjected to the primary polishing brush treatment; Polishing the surface of the pickled hot-rolled steel sheet with a secondary polishing brush; And a step of forming an alloy plating layer on the surface of the hot-rolled steel sheet, wherein the primary polishing brush treatment, the pickling treatment and the secondary polishing brush treatment are carried out successively and continuously, . ≪ / RTI >

Here, preferably, the secondary polishing brush treatment step, followed by a reduction heat treatment step is further included.

Preferably, the rotation speed of the secondary polishing brush is 1000 to 2000 rpm.

Preferably, the alloy plating layer contains 0.1 to 15% by weight of aluminum (Al), 1 to 4% by weight of magnesium (Mg), the balance of zinc (Zn) and inevitable impurities, And is formed by immersion in a bath.

Preferably, the alloy plating layer is composed of Zn, Zn-MgZn2 and Zn-Al-MgZn2.

Using the apparatus for producing an alloy-plated steel sheet according to the present invention. A zinc-aluminum-magnesium alloy plated steel sheet having an excellent surface appearance can be produced by removing foreign matters with an abrasive brush before and after pickling and forming roughness.

1 is a schematic view of a conventional apparatus for manufacturing an alloy-coated steel sheet.
2 is a schematic view of an apparatus for producing an alloy-plated steel sheet according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Wherever possible, the same or similar parts are denoted using the same reference numerals in the drawings.

All terms including technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. Predefined terms are further interpreted as having a meaning consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or very formal meanings unless defined otherwise.

The present invention relates to an apparatus for manufacturing a zinc-aluminum-magnesium alloy coated steel sheet excellent in surface appearance and plating adhesion, and a manufacturing method using the same.

In order to ensure the surface appearance and plating adhesion of the coated steel sheet, it is very important to secure the technology for removing foreign matter before hot-dip coating and controlling surface roughness. The present invention provides an apparatus and a method for manufacturing a zinc-aluminum-magnesium alloy plated steel sheet which has a complex pickling process before and after a conventional pickling process to provide a pickling equipment shortening effect and surface characteristics such as surface appearance and gloss.

More specifically, in the present invention, the surface scale layer which is not picked up by the Abrasive Brushing process before the pickling process is removed, the pickling property is increased to shorten the pickling process, and the polishing process The removal of the residual scale of the pickled hot-rolled steel sheet and the surface roughness of the steel sheet can be selectively and suitably controlled to secure the surface appearance and the plating adhesion.

By using such a manufacturing method as described above, the present invention can effectively remove scales of hot-rolled high-strength carbon steel and high-carbon steel containing alloying elements such as low carbon steel, ultra low carbon steel, manganese and silicon.

When the carbon steel is hot-rolled at a high temperature, a scale layer having a thickness of 5 to 20 micrometers remains on the surface layer depending on the temperature and the coiling temperature at the time of hot rolling and hot rolling. This hot-rolled scale can also be removed by the conventional chemical method of FIG. 1 using high temperature hydrochloric acid.

However, since the scale removal method by the conventional strong acid requires a large-scale acid pickling treatment facility, the initial investment cost is large and it is absolutely necessary to treat the waste liquid with large scale acid pickling. In addition, environmental problems such as inhibition of working environment due to the generation of acid vapor and generation of hazard due to waste acid treatment are also accompanied. Therefore, efforts to shorten the pickling process are required to minimize such problems.

Further, from the viewpoint of the quality of the pickling process, it is not easy to supply the surface of the pickled hot-rolled steel sheet according to the demand of the consumer in the current facility, since the surface quality is different depending on the steel component in the pickling treatment. In recent years, as the structural materials for automobiles and building materials have been required to have higher strength and lighter weight, hot rolled steel sheets to which abrasive elements such as manganese and silicon have been added in an amount of about 1 to 2% or more have been increasing, have.

Silicon (Si) added to improve mechanical properties is a major cause of deterioration of surface quality characteristics of high strength hot-rolled steel sheets. And when Si is added Steels of the high temperature hot rolling, the scale layer interface between a silicon oxide (SiO _2), and iron in the silicon-based oxide (Fe ₂ SiO ₄₎ is formed is not easy scale separation, using ordinary hydrochloric acid or sulfuric acid solution Striped oxides remain in the rolling direction even after the pickling treatment, leading to major defects in pickling treated high-strength hot-rolled steel sheets. The oxide remaining on the surface of the hot-rolled steel sheet is a major factor for causing tent defects and unplating in the subsequent cold rolling process and hot-dip galvanizing process. These residual scales are very difficult to remove by the chemical method of hydrochloric acid pickling. In the case of the high-strength Si-added hot-rolled steel sheet, since the fayalite formed on the scale interface is very tightly coupled with the inside of the steel sheet, it is not easy to propagate the crack to the interface by the scale breaker. Therefore, the scale breaker and the pickling treatment facility alone have a limitation in completely removing the ferrite light remaining on the surface of the high Si added steel.

In order to solve the above-mentioned problems, the present invention proposes a method of performing polishing brushing processes before and after the pickling process.

Hereinafter, an apparatus for manufacturing an alloy-plated steel sheet of the present invention will be described in detail with reference to the drawings.

Fig. 1 shows a schematic view of a conventional apparatus for manufacturing an alloy-plated steel sheet. The scales of the surface of the steel sheet have been crushed by using the scale breaker 4 in the hot rolled steel sheet having passed through the payoff reel 1, the welder 2 and the looper 3, The scale is removed by a pickling process including the hot dip galvanizing process 6 and then subjected to a heat treatment in the reduction heating furnace 7 and the alloying plating is performed through the hot dip galvanizing bath 8, the gas wiping process 9 and the alloying treatment device 10 A steel sheet was produced.

Fig. 2 shows a schematic view of an embodiment of the apparatus for manufacturing an alloy-coated steel sheet according to the present invention. The apparatus for manufacturing an alloy-plated steel sheet of the present invention is characterized in that, as a means for removing the scale of the hot-rolled steel sheet, conventionally, the apparatus for manufacturing an alloy-plated steel sheet according to the present invention comprises a first polishing section 21 and a second polishing section 2, The polishing portion 22 was disposed. Due to this difference, the apparatus for producing an alloy-plated steel sheet of the present invention can reduce the number of pickling treatments and is economical, and it is possible to completely remove foreign matters such as scales which were difficult to remove only by pickling treatment at the pick- A surface roughness can be easily formed, and a gold plated steel sheet having an excellent surface quality can be produced.

Hereinafter, a method for producing an alloy-plated steel sheet using the apparatus for producing an alloy-plated steel sheet of the present invention will be described in detail.

First, a hot rolled steel sheet is prepared by hot rolling. The kind of the hot-rolled steel sheet is not particularly limited, and conventionally used ultra-low carbon steel, low carbon steel, high strength carbon steel and high carbon steel can be applied.

The hot-rolled steel sheet may have a scale (iron oxide scale) formed during a manufacturing process such as hot rolling. Such a hot-rolled scale is required to be removed because there is a problem in that plating adherence is deteriorated in a subsequent plating process, resulting in deterioration of surface quality.

Next, a crack is generated in the hot-rolled scale formed on the surface of the hot-rolled steel sheet. The apparatus for generating cracks in the hot-rolled scale is not particularly limited as long as it is capable of generating physical cracks in the hot-rolled scale. However, the scale breaker 4, which can generate cracks in the hot-rolled scale by stretching and bending the hot- Is preferably used. The scale breaker may be composed of a tension bridle roll, an anti-camber roll, a leveller roll, and a bending roll capable of imparting tension and elongation. And anti-camber rolls and leveler rolls serve to fix the shape of the hot-rolled steel sheet flat.

In the case of using the scale breaker 4 as described above, the larger the elongation and the bending amount, the greater the crack generation effect of the scale layer. However, the excessive elongation and the bending amount have a risk of damaging the material of the hot- 3.0%, and the bending amount by the bending roll is preferably limited to 10 to 50 mm. If the elongation is less than 0.5% or the bending amount is less than 10 mm, the effect of cracking is insufficient. On the other hand, if the elongation exceeds 3% or the bending amount exceeds 50 mm, the material becomes small and the shape correction becomes excessive.

Next, the primary polishing brush process of the first polishing section 21 is performed. It is effective to rotate at a high speed in the reverse direction or the forward direction of the hot rolled steel strip by using a roll type brush. In the reverse direction, And in the forward rotation, the surface roughness control effect can be obtained.

The roughness of the brush roll is divided by the mesh number (mesh number). If the mesh number is small, the scale removal performance is increased because the particle size of the abrasive is large. However, too strong abrasion is caused by scratches or scratches It is necessary to select an appropriate roughness brush roll because it may cause defects. The primary polishing brush treatment can remove the hematite (Fe2O3), which is thermodynamically stable and difficult to pick up, which can increase the effect of the pickling process.

The polishing roll used in the primary polishing brush process is preferably composed of two or three stages at the upper and lower ends. The material of the brush roll is preferably a polymer nylon resin containing abrasive particles such as silicon carbide and aluminum oxide. If a polyurethane or phenol resin is mixed with the abrasive grains, the adhesion and polishing effect can be increased. The abrasive brush is suitable in the range of 200 to 400 on the basis of the mesh number. The primary purpose of the primary polishing brushing is to remove the stabilized Fe2O3 oxide in the surface layer and to promote pickling, and too strong polishing brushes can cause defects such as scratches on the steel sheet and scale interface layer below the scale. Therefore, it may cause defects after pickling. In order to effectively remove the Fe ₂ O ₃ scale layer for heat pickling of the surface layer through polishing brushing, a polishing brush of 200 to 400 mesh is suitable. The smaller the mesh, the thicker the abrasive particles entering the polishing brush. When the mesh size is about 200 to 400 mesh, the removal efficiency is excellent and does not cause defects such as scratches.

The pickling treatment in the mountain detail 5 of the present invention is carried out by the polishing brush treatment in the first polishing section 21 and the second polishing section 22 before and after the mountain detail 5, ), It is possible to shorten the installation to a length of about 50%. Therefore, the acid details (5) of the present invention can complete the necessary pickling process even if only two or three pickling baths are included. Preferably, the pickling solution which can be preferably applied to the pickling step has a concentration of hydrochloric acid of 15 to 20% and an acidic liquid temperature of 65 to 90 ° C.

The hot rolled steel sheet subjected to the pickling treatment in the mountain detail 5 is subjected to secondary polishing brushing of the second polishing portion 22 arranged subsequently. The secondary polishing brush treatment, which is carried out after the pickling treatment, removes the residual faylite and gives the surface roughness control and gloss. It is preferable that the polishing brush of the second polishing unit 22 rotate at a high speed in a range of 1000 to 2000 rpm and two to eight pairs of upper and lower brush rolls are arranged in series. In order to cope with the primary polishing brushing, it uses a brush made of fine material and rotates at a high speed. It rotates at a high speed to improve the efficiency of removal of residue in the surface layer, prevents deep surface scratches on the surface layer, Can be prevented. The number of abrasive brushes is more than two, and since more than eight abrasive brushes can remove scale residue, no further installation is required. When using multiple polishing brushes, it is effective to apply them in the order of rough polishing brushes to fine polishing brushes.

The roughness of the polishing brush of the second polishing part 22 is preferably in the range of 400 to 1200 on the basis of the mesh number according to the residual scale removing ability and the required surface roughness. If the mesh number of the polishing brush is less than 400, surface defects such as deep scratches and fine scratches are formed on the surface of the pickled hot-rolled steel sheet. If the mesh number is larger than 1200, removal of the residual ferrite is not easy. do. It is preferable that the polishing brush roll is sequentially applied from a small mesh number (coarse polishing) to a large one (soft polishing) so that the surface average roughness can be selectively adjusted to be less than 1.0 micrometer.

The direction of rotation of the polishing brush of the second polishing section 22 is such that the brush rolls in which two to eight pairs of upper and lower pairs are arranged in series in the second polishing section 22 are rotated in the order of reverse-forward-reverse- . By sequentially rotating the polishing brush rolls in the reverse direction in this order, the residual scale of the hot-rolled steel material can be effectively removed, and the surface average roughness can be ensured.

The secondary polishing brush treatment in the second polishing portion 22 improves the wettability of the plating liquid to be plated thereafter and makes the plating texture finer to improve the surface appearance quality.

After the secondary polishing brush treatment in the second polishing section 22, it may further include a reducing heat treatment step in the reduction heating furnace 7, preferably. The reduction heat treatment is carried out by a conventional method, and is not particularly limited, but it is preferable to heat at 500 to 550 캜 in a reducing atmosphere of 80 to 90% of nitrogen and 10 to 20% of hydrogen. In order to minimize the change of the material of the hot-rolled steel sheet and ensure the plating property, it is preferable to heat the steel sheet to the above-mentioned temperature of 500 to 550 ° C.

Preferably, after the first and second polishing brushes, the skin pass mill 23 may be additionally provided before forming the alloy plating layer.

Since the skin pass mill can adjust the surface roughness after the polishing brush treatment, the skin pass mill can be additionally provided if necessary. It is possible to completely remove scratched defects which can be finely remained by the polishing brush treatment, and it is preferable that surface elongation by the skin pass mill is 0.5% or less so as to minimize the surface defect while minimizing the material change of the steel sheet.

The hot-rolled steel sheet of the present invention, which has undergone the steps of removing the scale of the hot-rolled steel sheet as described above, carries out a step of forming an alloy plating layer on the surface of the hot-rolled steel sheet.

It is preferable that the alloy plating layer of the present invention is formed by dipping in a zinc-aluminum-magnesium alloy plating bath of the hot dip galvanizing bath 8, and the alloy plating bath is composed of 0.1 to 15 wt% aluminum, 1 to 4 wt% % Of Mg, the remainder of Zn, and inevitable impurities in the zinc-aluminum-magnesium alloy. When the Al content in the hot-dip galvanizing bath is less than 0.1%, the formation of Fe-Al intermetallic compounds is weak on the hot-rolled steel sheet and the plating layer interface and the coating adhesion is poor. On the other hand, There is a problem such as plating bath management and post-plating cooling management. When the Mg content in the hot dip galvanizing bath is less than 1%, the effect of improving the corrosion resistance by Mg addition can not be obtained. On the other hand, when the Mg content exceeds 4%, the formation of dross in the plating bath is excessive, However, there is a problem that the quality of the plating surface is deteriorated.

It is preferable that the temperature of the alloy plating bath is 440 to 500 ° C.

The plating structure of the present invention is preferably composed of a Zn single phase, a binary Zn-MgZn2 process phase and a ternary Zn-Al-MgZn2 process phase. This is because the interfacial cleansing through polishing brassing treatment and the promotion of nucleation increase the reactivity with Al in the plating bath and increase the interfacial layer distribution on the ternary Zn-Al-MgZn2 alloy.

It is preferable to adjust the amount of the plated steel sheet to be plated by air or gas wipers 9 using nitrogen at the upper end of the hot-dip galvanizing tank 8, and to adjust the amount of plating to 80 to 800 g / m ² .

Thereafter, a cooling process is performed in the cooling table 11. Next, surface adjustment and shape correction are performed by the skin pass mill 12 process and the tension leveler 13, and the post-process unit 14 Chromic acid treatment, resin coating, rust preventive oil treatment, or the like. Then, the hot-rolled steel sheet is wound in the form of a coil in the tensile reel 15 to produce a final zinc-aluminum-magnesium alloy coated steel sheet.

Hereinafter, the present invention will be described in more detail with reference to Examples.

[ Example  One]

The low-carbon hot-rolled steel sheet (thickness 2.0 mm x width 1200 mm) was continuously passed through a manufacturing apparatus for an alloy-coated steel sheet as shown in Fig. 2 at a line speed of 100 mpm under the treatment conditions shown in Table 1 below. , The residual scale was less than 1% in similar level and the average surface roughness was less than 1.0 micron (1.2 ~ 1.5 micron level in the case of acid steel) and the surface gloss was excellent.

division Treatment condition Primary polishing brush Two pairs of brush rolls (front and rear end rolls: mesh No. 240), number of revolutions 1000 rpm Low temperature heating Induction heating 100 kHz, temperature 100 캜 Pickling treatment Hydrochloric acid 15%, temperature 80 캜 Secondary polishing brush Two pairs of brush rolls (shear roll: mesh No. 600, rear roll: mesh No. 800), revolutions 1000 rpm Zn-Al-Mg plating condition Plating bath composition: Zn- 6% Al- 3% Mg, Pot temperature: 440 ° C, steel plate inlet temperature: 450 ℃

[ Example  2]

The low-carbon hot-rolled steel sheet (thickness: 2.3 mm x width: 1000 mm) was continuously passed through a manufacturing apparatus for an alloy-coated steel sheet as shown in Fig. 2 at a line speed of 80 mpm under the treatment conditions shown in Table 2 below. As a result, the residual scale was less than 1% and the average surface roughness was less than 1.0 micron. A steel sheet excellent in surface appearance was prepared by plating Zn-Al-Mg alloy.

division Treatment condition Primary polishing brush Two pairs of brush rolls (front and rear end rolls: mesh No. 240), number of revolutions 1000 rpm Low temperature heating Direct heating (surface temperature of steel plate 100 ℃) Pickling treatment Hydrochloric acid 15%, temperature 80 캜 Secondary polishing brush Two pairs of brush rolls (mesh number 600), number of revolutions 1200 rpm Zn-Al-Mg plating condition Plating bath composition: Zn- 3% Al- 3% Mg, Pot temperature: 440 ° C, steel plate inlet temperature: 450 ℃

[ Example  3]

The steel sheet was subjected to a heat treatment at a line speed of 50 mpm in a manufacturing apparatus for an alloy-plated steel sheet as shown in Fig. 2, in which a high carbon hot-rolled steel sheet (C: 0.4 wt%, Mn: 1.4 wt%, Si: 0.1 wt% . As a result, residual scale of less than 1% and average surface roughness of 1.0 micron level were obtained at comparable levels as compared with the hot-rolled steel strip obtained by the conventional pickling treatment, and surface gloss was excellent. A steel sheet excellent in surface appearance was prepared by plating Zn-Al-Mg alloy.

division Treatment condition Primary polishing brush Two pairs of brush rolls (front and rear end rolls: mesh No. 240), number of revolutions 1000 rpm Low temperature heating Direct heating (surface temperature of steel plate 120 ℃) Pickling treatment Hydrochloric acid 15%, temperature 85 캜 Secondary polishing brush 6 pairs of brush rolls (2 pairs of mesh No. 240, 2 pairs of mesh No. 400, 2 pairs of mesh No. 600), 1200 rpm
Zn-Al-Mg plating condition Plating bath composition: Zn- 1.6% Al- 1.6% Mg, Pot temperature: 440 ° C, steel plate inlet temperature: 450 ℃

[ Example  4]

(Thickness: 2.7 mm, X width: 1450 mm, containing C: 0.1 wt%, Mn: 1.6 wt%, and Si: 1.5 wt%) having a high Si content and a high Si content was used in a production apparatus for an alloy- As a result of continuous shipment under the processing conditions shown in Table 4 below, residual scale of less than 1% and average surface roughness of 0.5 micron level were obtained at comparable levels as compared with the hot-rolled steel strip obtained by the conventional pickling treatment, Respectively.

division Treatment condition Primary polishing brush Two pairs of brush rolls (front and rear end rolls: mesh No. 240), number of revolutions 1000 rpm Low temperature heating Induction heating frequency 200kHz, temperature 120 ℃ Pickling treatment Hydrochloric acid 15%, temperature 85 캜 Secondary polishing brush 8 pairs of brush rolls (3 pairs of mesh No. 240, 3 pairs of mesh No. 400, 2 pairs of mesh No. 600), 1200 rpm Zn-Al-Mg plating condition Plating bath composition: Zn- 11% Al- 3% Mg, Pot temperature: 480 ℃, steel plate inlet temperature: 490 ℃

While the illustrative embodiments of the present invention have been described with reference to the drawings, various modifications and alternative embodiments may be made by those skilled in the art. Such variations and other embodiments will be considered and included in the appended claims, all without departing from the true spirit and scope of the invention.

1: payoff reel 2: welder
3: looper 4: scale breaker
5: Pickles 6: Pickles
7: Reduction heating furnace 8: Hot dip galvanizing bath
9: Gas wiping 10: Alloying processing device
11: Cooling zone 12: Skin pass mill
13: tension leveler 14: post-processor
15: Tenshon reel 21: First polishing part
22: second polishing section 23: skin pass mill

Claims (9)

An apparatus for producing an alloy-plated steel sheet including an acidic substance for pickling the hot-rolled steel sheet,
A first polishing unit and a second polishing unit are provided at the front end and the rear end of the mountain detail, respectively, and a means for forming an alloy plating layer is provided at a rear end of the second polishing unit,
Wherein the first polishing portion is configured to first polish the surface of the hot-rolled steel sheet,
The pickling section is configured to pickle the hot-rolled steel sheet subjected to the first polishing and brushing in the first polishing section,
Wherein the second polishing section is configured to secondary-polish the surface of the hot-rolled steel sheet pickled in the mountain detail,
The means for forming the alloy plating layer comprises a plating bath containing 0.1 to 15% by weight of aluminum (Al), 1 to 4% by weight of magnesium (Mg), the balance of zinc (Zn) and unavoidable impurities and having a temperature of 440 to 500 ° C And the alloy plating layer is formed by alloying treatment, and
Wherein the primary polishing brush treatment, the pickling treatment and the secondary polishing brush treatment are excellent in surface appearance which is performed sequentially and continuously.
The polishing apparatus of claim 1, wherein the first polishing unit has two or three pairs of polishing brushes arranged in series at an upper end and a lower end, and the surface roughness of the polishing brush has a mesh number of 200 to 400, .
The polishing apparatus according to claim 1, wherein the second polishing unit is provided with 2 to 8 pairs of polishing brushes arranged in series at the upper and lower ends, and the surface roughness of the polishing brush is 200 to 1200 in mesh number, .
The method of claim 1, wherein the pickling unit comprises 2 to 3 pickling baths, and the pickling acid solution comprises 15 to 20% of hydrochloric acid and is maintained at a temperature of 65 to 90 캜. .
Preparing a hot-rolled steel sheet;
Crushing a scale formed on a surface of the hot-rolled steel sheet;
Subjecting the surface of the hot-rolled steel sheet to a primary polishing brush treatment;
Pickling the hot-rolled steel sheet subjected to the primary polishing brush treatment;
Polishing the surface of the pickled hot-rolled steel sheet with a secondary polishing brush; And
And forming an alloy plating layer on the surface of the hot-rolled steel sheet,
The alloy plating layer is formed by immersing in a plating bath containing 0.1 to 15% by weight of aluminum (Al), 1 to 4% by weight of magnesium (Mg), residual zinc (Zn) and unavoidable impurities and having a temperature of 440 to 500 캜, Wherein the primary polishing brush treatment, the pickling treatment, the secondary polishing brush treatment, and the formation of the alloy plating layer are formed successively and continuously with a surface appearance which is formed by an alloying treatment, and the primary polishing brush treatment, the pickling treatment, the secondary polishing brush treatment and the alloy plating layer.
6. The method of manufacturing an alloy-plated steel sheet according to claim 5, further comprising a reducing heat treatment step prior to the step of forming the alloy plating layer.
6. The method of manufacturing an alloy-plated steel sheet according to claim 5, wherein the secondary polishing brush has a surface speed of 1000 to 2000 rpm.
delete 6. The method of manufacturing an alloy-plated steel sheet according to claim 5, wherein the alloy plating layer is formed of Zn, Zn-MgZn2 and Zn-Al-MgZn2.

Images