KR101284420B1 - HOT DIP PLATED STEEL SHEET CONTAINING Al PLATING LAYER AND METHOD FOR MANUFACTURING THE SAME - Google Patents

Abstract

The present invention relates to a method for manufacturing a high strength hot dip galvanized steel sheet, wherein an Al-Mg (AM) -based or Al-Si (AS) -based plating layer is formed on a surface of the steel sheet, wherein the plating layer is magnesium (Mg): 10 to 11 wt% Or silicon (Si): by manufacturing a hot-dip plated steel sheet controlled to a composition of 10 to 11% by weight, while ensuring excellent corrosion resistance, peeling and plating wettability, and relates to an invention for producing a plated steel sheet excellent in formability .

Description

Hot-dip galvanized steel sheet comprising aluminum-based plating layer and method for manufacturing the same {HOT DIP PLATED STEEL SHEET CONTAINING Al PLATING LAYER AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a plated steel sheet manufacturing technology, and more particularly, to a technology for manufacturing a plated steel sheet having an Al-Mg (AM) -based or Al-Si (AS) -based non-linked plating layer except for Zn.

Recently, the application of high-strength steel sheet in consideration of collision safety in order to secure the safety of passengers and drivers has tended to increase gradually.

In addition, the application of the surface-treated steel sheet is increasing in order to meet the increase in the anti-rust warranty.

In particular, since the corrosion resistance of automotive steel sheets depends on the plating thickness, the demand for hot-dip galvanized steel sheets which can be plated at a low price is rapidly increasing.

Among them, there are zinc-based and aluminum-based plated steel sheets which are plated with a surface for improving corrosion resistance.

In the case of manufacturing a high-strength component using such a plated steel sheet, there is an advantage that the plating layer on the surface prevents oxidation of the base iron even after high temperature heating and molding.

In addition, the zinc-based compound in the high-temperature heating process zinc oxide layer, aluminum-based plated steel sheet is formed on the surface of the aluminum oxide layer to give the effect of suppressing the evaporation of the plating layer, not only to enable the production of high-strength components preserving the plating layer, It gives a good corrosion resistance compared to cold rolled steel.

The plated layer of the plated steel sheet used to impart corrosion resistance includes a Zn-Fe alloy, a Zn-Mn alloy, and a Sn-8 wt% Zn alloy.

Compared with Sn, the plated steel sheet having a Zn-Fe alloy layer is superior in price competitiveness due to low manufacturing cost, but there is a problem in that the price fluctuation rate of Zn is severe and unstable.

As a result, while the plate is heated to the temperature range near the melting point of the plated layer, mutual diffusion of Fe and Zn occurs between the base plate and the plated layer, and the Fe weight% in the plated layer rapidly increases to generate a large amount of Fe oxide on the surface. .

The Fe oxide thus produced reduces the interfacial bonding force between the plating layer and the base iron, which causes peeling of the plating layer during high temperature processing, and promotes oxidation of the base iron.

Therefore, in order to mass-produce a plated steel sheet having a Zn-Fe alloy layer, research to suppress the generation of Fe oxide should be conducted.

In this regard, there is provided a plated steel sheet having an Al-5 wt% Si and Zn-Fe alloy layer under application and review in a mass production line. In addition, the parts manufactured by using the same have excellent corrosion resistance compared to the parts from which the oxide layer is removed after molding using a cold rolled steel sheet having no plating layer.

However, even when using a Zn-Al or Zn-Al-Si-based alloy layer using a sacrificial method, the performance that exceeds the critical corrosion resistance that can be present in the steel sheet is currently required, Zn is 30 years or so Since it is classified as a risk resource depletion, the price fluctuations are large, and supply and demand is unstable, and there is a problem that it is difficult to manufacture a normal coated steel sheet product.

An object of the present invention is to solve the above problems, in particular, by eliminating the Zn component, and finally produced by using a non-bonded molten plating solution composed of Al-Mg (AM) or Al-Si (AS) It is to make a hot-dip steel plate excellent in corrosion resistance and workability.

In addition, another object according to the present invention is to add sufficient Si and Mn to the plated steel sheet to ensure the plating wettability, and to ensure excellent peeling (Peeling) characteristics.

Hot-dip steel sheet according to an embodiment of the present invention is M: 10 to 11% by weight (M is magnesium (Mg) or silicon (Si)) and Al-Mg (AM) consisting of the remaining aluminum (Al) and unavoidable impurities or It characterized in that it comprises an Al-Si (AS) via-based plating layer.

Here, the plating layer may further include manganese (Mn): 2 to 5% by weight.

In addition, the method for manufacturing a hot dip galvanized steel sheet according to an embodiment of the present invention is M: 10 to 11% by weight (M is magnesium (Mg) or silicon (Si)) and the remaining plating solution consisting of aluminum (Al) and inevitable impurities And forming an Al-Mg (AM) or Al-Si (AS) via-based plating layer by continuously immersing the cold rolled steel sheet in the plating bath.

According to the method for manufacturing a hot-dip galvanized steel sheet according to the present invention, by using a plated steel sheet having an Al-Mg (AM) or Al-Si (AS) via-based plated layer, it is possible to solve the incompleteness of cost fluctuations in using zinc (Zn). It can reduce the production cost.

In addition, the present invention can secure excellent corrosion resistance by using an Al-based plating layer.

In addition, since Si and Mn, which are advantageous for securing peeling property and plating wettability, may be added in a large amount, the characteristics of the plated steel sheet may be freely adjusted.

In addition, the hot-dip galvanized steel sheet according to the present invention can be easily processed even a complex shape by the excellent plating properties as described above, and provides the effect of forming a molded article having a high tensile strength of 140kg / mm ² or more. do.

1 is a flowchart illustrating a method of manufacturing a hot dip galvanized steel sheet according to the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a hot dip galvanized steel sheet having an Al-Mg (AM) or Al-Si (AS) via-based plating layer and a method of manufacturing the same will be described with reference to the accompanying drawings.

1 is a flowchart illustrating a method of manufacturing a hot dip galvanized steel sheet according to the present invention, and FIG. 2 is a flowchart illustrating a method of forming a hot dip galvanized steel sheet according to the present invention.

As shown in FIG. 1, the hot-dip steel sheet according to the present invention excludes the Zn component and continuously immerses the steel sheet in a molten plating solution containing Mg or Si, the balance of Al and inevitable impurities.

To this end, first, by weight%, carbon (C) 0.1 ~ 0.4%, silicon (Si) 0.5% or less, nitrogen (N) 0.1% or less, aluminum (Al) 0.01 ~ 0.1%, phosphorus (P) 0.05% or less , Manganese (Mn) 0.8 ~ 2%, boron (B) 0.002 ~ 0.01%, molybdenum (Mo) or chromium (Cr) 0.1 ~ 0.5%, but the B / N atomic ratio is adjusted to 1 or more, and inevitably A hot rolled steel sheet including impurities to be added is formed. (S110)

Here, the hot rolled steel sheet may be used a steel sheet having a more various composition range in addition to the composition range. Therefore, the composition range of the steel sheet according to the present invention is not limited to the above description.

However, when forming a hot rolled steel sheet having a composition range as described above it was possible to further improve the plating properties, it was also possible to obtain high strength properties after molding.

In addition, as a steel sheet for plating, a cold rolled steel sheet manufactured by cold rolling the hot rolled steel sheet may be used.

Therefore, the hot-dip steel sheet manufacturing method according to the present invention can be applied to both hot-rolled steel sheet and cold rolled steel sheet without limitation.

When the step (S110) of preparing a steel sheet to be used for plating is completed as described above, a step (S120) of hot-dipting the steel sheet is performed. At this time, the plating layer according to the present invention forms an Al-Mg (AM) or Al-Si (AS) via-based plating layer (S130).

Next, an alloying heat treatment step (S130) may be performed as necessary, and the plating process is completed by the end of the alloying heat treatment.

Here, Al-Mg (AM) alloy is a high corrosion-resistant plating layer according to an embodiment of the present invention shows a case containing 10 to 11% by weight of Mg composition.

At this time, aluminum (Al) has an effect of stabilizing the plating layer together with silicon (Si). Therefore, when the addition amount of aluminum (Al) is less than 84% by weight, the corrosion resistance and stabilization characteristics of the plating layer may be lowered.

In addition, aluminum (Al) has a property that the plating is stable even if a large amount of manganese (Mn) that can improve the plating wettability is added.

At this time, the content of manganese (Mn) is preferably 2 to 5% by weight of the total weight of the plating layer. When the content of manganese (Mn) is less than 2% by weight, the plating wettability is inferior, and when the content of manganese (Mn) is more than 5% by weight, aluminum (Al) is out of the range for stabilization. This can be degraded.

Magnesium (Mg) is an element that can contribute to an increase in strength of the plated layer and the steel sheet, and when the content is less than 10% by weight, the above effect cannot be obtained.

In addition, when the content of magnesium (Mg) exceeds 11% by weight, the plating adhesion may be lowered, which may cause deterioration of molding characteristics of the steel sheet.

In addition, Al-Si (AS) alloy represents a case containing a Si composition of 10 to 11% by weight as a high corrosion-resistant plating layer according to another embodiment of the present invention.

At this time, the properties for aluminum are applied in the same manner as in the case of the AM alloy.

In addition, silicon (Si) is an element that is involved in the strength and surface properties of the plating layer, and when the content is less than 10% by weight, plating is not normally performed.

On the contrary, when the content of silicon (Si) exceeds 11% by weight, a peeling property is lowered, thereby causing a problem in that the plating is peeled off.

In addition, the temperature of the molten plating solution in the plating process is preferably adjusted to 680 ~ 750 ℃. And the temperature for alloying heat treatment of the steel sheet drawn from the plating bath is preferably 730 ~ 800 ℃.

In the present invention, when the temperature of the molten plating solution is less than 680 ℃, or the alloying heat treatment temperature is less than 730 ℃ may cause a problem that the sufficient plating is not made.

In addition, when the temperature of the molten plating liquid was higher than 750 ° C or the alloying heat treatment temperature was higher than 800 ° C, plating adhesiveness was lowered.

Next, in order to investigate the hot-dip steel sheet properties of the present invention formed as described above may be determined by measuring the state of the plating layer after performing a molding process such as hot stamping.

First, when the hot-dip steel sheet is formed as described above, the plated steel sheet is put into a heating furnace and heated.

Here, the heating temperature provided in the heating furnace may be 800 ° C to 1000 ° C, preferably 850 ° C to 950 ° C.

In addition, the heating rate of heating the plated steel sheet in the furnace is not limited, but considering the production rate of at least 5 ~ 100 ℃ / sec. It is preferable to heat the plated steel sheet at a speed of.

The heating temperature is below 800 ° C., or the heating rate is 5 ° C./sec. If it is less than the working rate is too low, if the heating temperature exceeds 1000 ℃ or if the heating rate exceeds 100 ℃ / sec. May damage the plated layer.

Next, the plated steel sheet is molded and quenched, and the hot-rolled steel sheet molded body according to the present invention is completed through the final finishing treatment.

At this time, the quenching speed to be formed is 20 ~ 100 ℃ / sec. It is desirable to keep it.

The reason is that the plated steel sheet used in the present invention has an austenite structure when heated to a high temperature, but when the quenching rate exceeds 100 ° C./sec., The phase transformation does not occur to the martensite structure. Because it becomes.

Further, the hot dip galvanized steel sheet of the present invention heated to a high temperature was 20 ° C / sec. When cooled at less than a cooling rate, the tissue will have pearlite or bainite tissue and will not have sufficient strength.

In addition, when the forming and quenching step as described above, the plated steel sheet to form a martensite (martensite) structure can be significantly improved the tensile strength of the final molded product.

In other words, the hot-dip coated steel sheet may be quenched simultaneously with molding to improve the tensile strength of the hot-dip steel sheet. In this case, when the Al-Mg (AM) -based or Al-Si (AS) -based non-lead plating layer according to the present invention is used, the strength can be improved without deteriorating the molding characteristics.

Accordingly, an embodiment of a hot-dip coated steel sheet and a molded article which is protected by an Al-Mg (AM) -based or Al-Si (AS) -based via-based plating layer and which can maintain excellent corrosion resistance will be described as follows. .

Example

Hereinafter, it will be described by a specific embodiment that is manufactured by the method for producing a hot-dip galvanized steel sheet according to an embodiment of the present invention is excellent in coating adhesion and corrosion resistance.

Details that are not described here are omitted because they can be sufficiently inferred by those skilled in the art.

1. Examples and Comparative Examples

≪ Example 1 >

By weight%, carbon (C) 0.4%, silicon (Si) 0.5%, nitrogen (N) 0.1%, aluminum (Al) 0.1%, phosphorus (P) 0.05%, manganese (Mn) 0.8%, boron (B) A steel plate having a thickness of 1.2 mm consisting of 0.002%, molybdenum (Mo) and 0.5% of the remaining iron and inevitable impurities was prepared.

Next, a hot dip plating process was performed such that the Al-11% by weight Mg alloy (AM) plating layer had an adhesion amount of 50 g / m ² based on the cross section on the surface of the steel sheet. At this time, the temperature of the molten plating solution was maintained at 680 ℃, the temperature of the alloying heating section and the temperature of the alloying annealing section was maintained at 730 ℃.

As a result, a hot-dip steel sheet specimen having Al-Mg (AM) -based or Al-Si (AS) -based via-based plating layers formed on both surfaces thereof was formed.

<Example 2>

A specimen was prepared in the same manner as in Example 1 except that the component of the plating layer formed on the surface of Example 1 was an Al-11% by weight Si (AS) alloy.

&Lt; Comparative Example 1 &

The same steel sheet as in Example 1 was used as a specimen except that no plating layer was formed on the surface.

Comparative Example 2

A specimen was prepared in the same manner as in Example 1 except that the component of the plating layer formed on the surface of Example 1 was Zn-11% by weight Fe (ZF).

&Lt; Comparative Example 3 &

A specimen was prepared in the same manner as in Example 1 except that the component of the plating layer formed on the surface of Example 1 was Al-5% by weight Si (AS).

2. Property Measurement

(1) appearance evaluation after heating

In the above Examples and Comparative Examples was evaluated by visual observation of the appearance state of the specimen after heating for 5 minutes at a temperature of 900 ℃.

(2) Evaluation of moldability (plating adhesion)

In general, formability means how well a molding is formed into a desired shape by a stamping process. However, in the present invention, a plated steel sheet is used as a forming member. Therefore, it is important that the surface of the coating layer be peeled off after stamping. Therefore, moldability was determined based on this.

Moldability (plating adhesion) evaluation was performed by visually observing whether the plating layer in the molded part was damaged after stamping.

For the stamping, the specimens of Examples 1 and 2 and Comparative Examples 1 to 3 were placed in a heating furnace in an air atmosphere, heated at 900 ° C. for 5 minutes, and then removed. At this time, the temperature of the specimen was to reach 900 ℃ after about 1 minute, the retention time after reaching to 4 minutes.

Thereafter, the specimens, which became hot, were formed using a stamping apparatus. At this time, stamping conditions were made into drawing height 25mm, shoulder radius R 5mm, blank diameter 90mm, punch diameter 50mm, and die diameter 53mm.

(3) Evaluation of peeling property (paint adhesion)

Each molded article produced for evaluation of the formability was subjected to zinc phosphate treatment under normal image processing conditions with PBL-3080 manufactured by Nippon Parkarizing Co., Ltd., and then the electrodeposition coating GT-10 made by Kansai Paint was applied to a voltage. Electrodeposition coating was carried out by 200V of slope energization, and sintered and coated at a sintering temperature of 150 ° C. for 20 minutes. At this time, the thickness of the coating film was about 20 micrometers.

Each specimen was immersed in 50 ° C. ion-exchanged water and taken out after 240 hours. Using a cutter knife, a scratch was placed so that the bottom layer of the coating film was exposed in a checkerboard grid shape having a width × length of 1 mm × 1 mm. When 3M and TM polyester tape 396 / transparent) were stuck and removed, the peeling test of the coating film was done by counting the number of squares of the coating film which remain | survived.

In this case, the total number of squares was set to 100, and the evaluation standard was marked as good (O) when the number of remaining squares was 90 to 100, and marked as bad (X) when 0 to 89.

(4) corrosion resistance evaluation

Specimens were prepared in the same manner as in the above evaluation of peeling (coating adhesion), and a salt spray test was conducted for 480 hours in the manner specified in JIS Z2371.

Corrosion resistance evaluation was made here by measuring the coating film blister width or rust width from a scratch.

Evaluation criteria were described as very good (◎) of less than 0mm ~ 1mm based on the larger value of the rust width, coating film blister width, 1mm ~ less than 2mm was described as good (○), more than 2mm and less than 4mm normal ( (Triangle | delta)) and 4 mm or more were described as defect (X).

3. Property measurement result and analysis

[Table 1]

Ⅹ: defective, △: normal, ○: good, ◎: very good

Table 1 shows the measurement results of the physical properties of the specimen prepared by the method of Examples 1 and 2, Comparative Examples 1 to 3. The numerical value described before the component which comprises the plating layer of Table 1 means weight%.

Referring to Table 1, when the non-plated cold rolled steel sheet was used as in Comparative Example 1, a thick oxide film was formed on the surface, and after heating to 900 ° C., the surface turned black, and the oxide was peeled off during hot stamping molding. .

In addition, in the case of Comparative Example 1, it was found that coating adhesion and corrosion resistance were poor.

In addition, in the case of a coated steel sheet having a Zn-11% by weight Fe plated layer as in Comparative Example 2, ordinary results were obtained in appearance state, formability (plating adhesiveness) and peeling property after heating. In the case of a plated steel sheet having a 5% by weight Si plating layer, the appearance state after heating, moldability (plating adhesion) and peeling property had good properties, but in the evaluation of corrosion resistance, a normal (Δ) result was shown.

On the other hand, in Example 1 and Example 2 in which the Al-11% by weight Mg layer and the Al-11% by weight Si layer were formed as the via-based plating layer according to the present invention, the appearance after forming and the formability (plating adhesion) It was found that both peeling and corrosion resistance had excellent properties.

Hereinafter, in a plated steel sheet in which an Al-11% by weight Mg layer and an Al-11% by weight Si layer are plated on a surface which is shown to have excellent properties in the physical property measurement and results through further examples and comparative examples, the plating deposition amount The conditions that can have better physical properties while changing the heating temperature will be described.

<Examples 3 to 22>

An AM-based plating layer was formed, but the elements were controlled in a composition range as shown in Table 2 below.

The rest of the conditions were the same as those in Example 1, and the plating deposition amount (g / m ² ) was changed to (10, 30, 50, 70, 90) g / m ^{2 based} on one side, and in each plating deposition amount, After the heating, the appearance temperature, moldability (plating adhesion), tensile strength, peeling resistance and corrosion resistance were evaluated while changing the heating temperature to (800, 850, 900, 950, 1000) ° C., respectively. It is shown in [Table 2].

At this time, the appearance evaluation, formability, coating adhesion and corrosion resistance evaluation were made in the same manner as described above, and further measured tensile strength was carried out in JIS Z 2241 standard using a JIS No. 5 size sample.

<Comparative Examples 4 to 8>

An AM-based plating layer was formed, but the elements were controlled in a composition range as shown in Table 2 below.

The rest of the conditions were the same as those in Example 1, and the plating deposition amount (g / m ² ) was changed to (10, 30, 50, 70, 90) g / m ^{2 based} on one side, and in each plating deposition amount, After the heating, the appearance temperature, moldability (plating adhesion), tensile strength, peeling resistance and corrosion resistance were evaluated while changing the heating temperature to (800, 850, 900, 950, 1000) ° C., respectively. It is shown in [Table 2].

At this time, the appearance evaluation, formability, coating adhesion and corrosion resistance evaluation were made in the same manner as described above, and further measured tensile strength was carried out in JIS Z 2241 standard using a JIS No. 5 size sample.

[Table 2]

<Examples 23 to 42>

An AS-based plating layer was formed, but the elements were controlled in a composition range as shown in Table 3 below.

The rest of the conditions were the same as those in Example 1, and the plating deposition amount (g / m ² ) was changed to (10, 30, 50, 70, 90) g / m ^{2 based} on one side, and in each plating deposition amount, After the heating, the appearance temperature, moldability (plating adhesion), tensile strength, peeling resistance and corrosion resistance were evaluated while changing the heating temperature to (800, 850, 900, 950, 1000) ° C., respectively. It is shown in [Table 3].

At this time, the appearance evaluation, formability, coating adhesion and corrosion resistance evaluation were made in the same manner as described above, and further measured tensile strength was carried out in JIS Z 2241 standard using a JIS No. 5 size sample.

<Comparative Examples 9 to 13>

An AS-based plating layer was formed, but the elements were controlled in a composition range as shown in Table 3 below.

The rest of the conditions were the same as those in Example 1, and the plating deposition amount (g / m ² ) was changed to (10, 30, 50, 70, 90) g / m ^{2 based} on one side, and in each plating deposition amount, After the heating, the appearance temperature, moldability (plating adhesion), tensile strength, peeling resistance and corrosion resistance were evaluated while changing the heating temperature to (800, 850, 900, 950, 1000) ° C., respectively. It is shown in [Table 3].

At this time, the appearance evaluation, formability, coating adhesion and corrosion resistance evaluation were made in the same manner as described above, and further measured tensile strength was carried out in JIS Z 2241 standard using a JIS No. 5 size sample.

[Table 3]

Referring to [Table 2] and [Table 3] it can be further classified into Examples and Comparative Examples, it can be seen that the appearance after heating is generally good.

However, in Comparative Examples 4 to 6 and Comparative Examples 9 to 11, in which plating layers having Mg or Si of less than 10% by weight were formed, tensile strengths of 140 kg / mm ² or more were not obtained. You can see that.

Next, in Comparative Examples 7, 8, 12, and 13 in which a plating layer having an Mg or Si of more than 11 wt% was formed, good corrosion resistance and peeling resistance were secured, but tensile strengths of 140 kg / mm ² or more were not obtained. .

Therefore, in order to have both formability, tensile strength of 140 kg / mm ² or more, excellent peeling resistance, and corrosion resistance, as in the embodiments of the present invention, the plating deposition amount should be 10 g / m ² or more based on one side, and the heating temperature is 850. It can be seen that it should be at least ℃.

In particular, in order to have more excellent corrosion resistance, peeling properties and tensile strength, the plating deposition amount was at least 50g / m ^{2 It} was found that the heating temperature should be at least 850 ℃.

In addition, when the plating deposition amount exceeds 90g / m ^{2 It} is not preferable in terms of economics, as described above, it was not set in the conditions of the embodiment. When the heating temperature is higher than 1000 ℃, the tensile strength value decreases due to the coarsening of austenite grain size, so the heating temperature should be 1000 ℃ or less.

As described above, by using the high strength hot dip galvanized steel sheet according to the present invention, super high strength hot dip galvanized steel sheet such as a center pillar of an automobile, a roof rail of an automobile, and a sealside of an automobile having a tensile strength of 140 kg / mm ² or more easily. It can manufacture.

In addition, since the plating layer is not damaged during the manufacturing process, not only excellent plating characteristics may be secured, but also manufacturing costs may be reduced.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments, but may be modified in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (9)

M: 10 to 11% by weight (M includes magnesium (Mg) or silicon (Si)), manganese (Mn): 2 to 5% by weight further, Al made of the remaining aluminum (Al) and inevitable impurities A hot-dip steel sheet comprising a Mg (AM) or Al-Si (AS) via-based plating layer.
delete The method of claim 1,
The Al-Mg (AM) or Al-Si (AS) via-based plating layer is
Hot-dip galvanized steel sheet, characterized in that the plated with a coating amount of 10 ~ 90g / m ² based on the cross section of the plated steel sheet.
(a) M: 10 to 11% by weight (M includes magnesium (Mg) or silicon (Si)), manganese (Mn): 2 to 5% by weight further, the remaining aluminum (Al) and unavoidable impurities Forming a molten plating solution comprising: And
(b) continuously immersing a cold rolled steel sheet in a plating bath in which the molten plating solution is stored to form an Al-Mg (AM) or Al-Si (AS) non-based plating layer; manufacturing a hot-dip steel sheet comprising a Way.
delete 5. The method of claim 4,
In the step (b)
The molten plating liquid is heated to a temperature of 680 ~ 750 ℃ characterized in that the hot-dip steel sheet manufacturing method.
5. The method of claim 4,
(c) the steel sheet drawn out from the plating bath
Alloying heating step; hot-dip steel sheet manufacturing method characterized in that it further comprises.
The method of claim 7, wherein
The alloying heating step
Hot-dip steel sheet manufacturing method characterized in that carried out at a temperature of 730 ~ 800 ℃.
5. The method of claim 4,
The cold rolled steel sheet
0.1 to 0.4% by weight of carbon (C), 0.5% or less of silicon (Si), 0.1% or less by weight of nitrogen (N), 0.01 to 0.1% by weight of aluminum (Al), 0.05% or less by weight of phosphorus (P), manganese (Mn) ) 0.8 to 2% by weight, containing 0.002 to 0.01% by weight of boron (B), 0.1 to 0.5% by weight of molybdenum (Mo) or chromium (Cr), but the B / N atomic ratio is 1 or more, inevitable with the rest of iron Method for producing a hot-dip steel sheet, characterized in that consisting of impurities.

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