KR20230165012A - Hot-dip galvanized steel sheet having excellent coating adhesion and method for manufacturing thereof - Google Patents

Abstract

The present invention relates to a steel sheet suitable as a material for automobiles, and more specifically, to a high-strength hot-dip galvanized steel sheet with excellent plating adhesion and a method of manufacturing the same.

Description

High-strength hot-dip galvanized steel sheet with excellent plating adhesion and manufacturing method thereof {HOT-DIP GALVANIZED STEEL SHEET HAVING EXCELLENT COATING ADHESION AND METHOD FOR MANUFACTURING THEREOF}

The present invention relates to a steel sheet suitable as a material for automobiles, and more specifically, to a high-strength hot-dip galvanized steel sheet with excellent plating adhesion and a method of manufacturing the same.

In response to recently emerging environmental regulations, demand for ultra-high strength steel sheets is rapidly increasing as a way to respond to stricter automobile fuel efficiency regulations and strengthened collision safety regulations.

In addition, while improvements in fuel efficiency are required to achieve national carbon emissions reduction goals, the weight of automobiles continues to increase due to increased performance and various convenience devices. To solve these problems, demand for ultra-high strength steel plates continues to increase. is increasing.

Accordingly, steel companies are focusing on the development of high-strength steel sheets such as Dual Phase (DP) steel, Transformation Induced Plasticity (TRIP) steel, and Complex Phase (CP) steel.

Generally, in order to increase the strength of automobile steel sheets, a large amount of elements such as Si, Mn, and Al are added to the steel. However, steel sheets containing these elements have a problem in that the elements generate oxides on the surface of the steel sheet during annealing heat treatment, thereby impairing plating properties and adhesion during hot-dip galvanizing.

In order to solve this problem, in Patent Document 1, a steel sheet containing a large amount of Si and Al is subjected to reduction annealing using a direct-fired reduction heating furnace with an air-fuel ratio of 0.7 to 1.2, so that the surface layer of Fe oxide is converted to reduced iron (reduced iron). It is disclosed that an excellent plating surface can be secured as the alloying inhibition layer is well developed.

However, during the reduction annealing process, oxides of Si, Mn, or Al formed at the interface between Fe oxide and the base steel sheet take the form of a layer, which has the disadvantage of causing plating peeling, in which the plating layer falls off after galvanizing.

Accordingly, there is an urgent need for technology that can secure plating adhesion as well as plating properties of high-strength hot-dip galvanized steel sheets.

Japanese Patent Publication No. 2005-154856

One aspect of the present invention is to provide a high-strength hot-dip galvanized steel sheet with improved plating adhesion by optimizing the alloy composition and process conditions in the steel, and a method for manufacturing the same.

The object of the present invention is not limited to the above-described contents. Anyone skilled in the art to which the present invention pertains will have no difficulty in understanding the additional problems of the present invention from the overall content of the present invention specification.

One aspect of the present invention is a base steel sheet containing 0.7% or less (excluding 0%) of silicon (Si) by weight; And a hot-dip galvanized steel sheet including a hot-dip zinc-based plating layer formed on at least one surface of the base steel sheet,

High-strength hot-dip galvanizing with excellent plating adhesion, characterized in that the Si concentration integral value of the GDS profile measured from the interface between the base steel sheet and the plating layer to a depth of 0.1㎛ in the thickness direction of the base steel sheet is 0.1%·㎛ or less (excluding 0). Provides steel plates.

Another aspect of the present invention includes preparing a cold-rolled steel sheet using a base steel sheet containing 0.7% or less (excluding 0%) of silicon (Si) by weight; Annealing and heat treating the cold rolled steel sheet; And manufacturing a hot-dip galvanized steel sheet by immersing the annealed heat-treated cold-rolled steel sheet in a hot-dip galvanizing bath,

The annealing heat treatment step consists of a first heat treatment step of heating to 550 to 700° C. while supplying oxygen into an annealing furnace into which the cold rolled steel sheet is charged, and a second heat treatment step of heating to 700 to 850° C. in a nitrogen reduction atmosphere. , In the first heat treatment step, an Fe oxide layer is formed, and the oxygen concentration (ppm), oxygen supply temperature (°C), and line speed (L/S) are adjusted so that the thickness of the Fe oxide layer calculated by the following equation (1) is 50 to 250 nm. , mpm), and provides a manufacturing method for manufacturing a high-strength hot-dip galvanized steel sheet with excellent plating adhesion.

Equation (1)

Thickness of Fe oxide layer (nm) = -26.5 + (0.08 × oxygen concentration (ppm)) + (0.11 × oxygen supply temperature (℃)) - (0.28 × L/S (mpm))

According to the present invention, by optimizing the alloy composition and process conditions in the steel, the shape of the oxide formed immediately below the interface between the plating layer and the base steel plate is intermittently formed, and by controlling the concentration at which Si in the steel is concentrated directly under the reduced Fe. It is possible to provide a high-strength hot-dip galvanized steel sheet with improved plating adhesion.

Figure 1 shows GDS measurement results according to an embodiment of the present invention.
Figure 2 shows the TEM-DES mapping results according to an embodiment of the present invention.

The inventors of the present invention recognized the problem of low plating adhesion of hot-dip galvanized steel sheets, which are widely used as steel sheets for automobiles, due to oxidizing elements (eg, Si, Mn, etc.) contained in the steel.

In particular, when heat treating steel containing a large amount of Si, Si and Mn oxides are formed as Si and Mn in the steel are replaced with Fe oxide directly under the Fe oxide layer. At this time, a layer form due to the large amount of Si is formed. It was discovered that there is a problem in that the plating layer falls off along this oxide as it is formed in the horizontal direction (rolling direction) of the steel.

Accordingly, the present inventors conducted in-depth research to improve the plating adhesion of hot-dip galvanized steel sheets, and derived a means to control the Si content in the steel and the shape of the oxide formed during the heat treatment of the steel. The present invention has been completed.

Hereinafter, the present invention will be described in detail.

A high-strength hot-dip galvanized steel sheet according to one aspect of the present invention includes a base steel sheet; and a molten zinc-based plating layer formed on at least one surface of the base steel plate.

In the present invention, hot-dip galvanized steel sheet is a concept that includes not only hot-dip galvanized steel sheet (GI steel sheet), but also alloyed hot-dip galvanized steel sheet (GA), as well as galvanized steel sheet on which a zinc-based plating layer mainly containing zinc is formed. It is necessary to pay attention to. The fact that zinc is mainly included means that the proportion of zinc is the highest among the elements contained in the plating layer. However, in alloyed hot-dip galvanized steel sheets, the ratio of iron may be higher than that of zinc, and even steel sheets with the highest ratio of zinc among the remaining components excluding iron can be included in the scope of the present invention.

According to the research results of the present inventors, when the distribution of silicon (Si) concentration is controlled in a specific area from the interface between the base steel sheet and the plating layer in the thickness direction of the base steel sheet, plating adhesion can be improved.

Specifically, it is preferable that the Si concentration integral value of the GDS profile measured from the interface between the base steel sheet and the plating layer to a depth of 0.1 ㎛ in the thickness direction of the base steel sheet is 0.1%·㎛ or less (excluding 0). More advantageously, it is preferably 0.05%·μm or less (excluding 0).

In addition, it is preferable that the maximum peak concentration of Si element in the GDS profile measured from the interface between the base steel sheet and the plating layer to a depth of 0.1㎛ in the thickness direction of the base steel sheet is 2% or less (excluding 0). More advantageously, it is preferred that the maximum concentration is 1.5% or less.

As a non-limiting example, when the inside of the base steel sheet in the thickness direction is measured from the interface between the base steel sheet and the plating layer using GDS (Glow Discharge Spectroscopy), the Si concentration profile may have the form shown in FIG. 1.

The integrated value of Si concentration of the GDS profile measured from the interface of the base steel sheet and the plating layer to a depth of 0.1㎛ in the thickness direction of the base steel sheet exceeds 0.1%·㎛, or the peak maximum concentration of Si element exceeds 2%. This means that surface enrichment of Si was not suppressed. In other words, Si and Mn in the steel form an internal oxide in the form of a layer, causing plating peeling, which ultimately leads to deterioration of plating adhesion.

Meanwhile, the type of base steel plate targeted in the present invention is not limited as long as it is a high-strength steel suitable for automobile use, but it is preferable to contain 0.7% or less (excluding 0%) of silicon (Si) by weight.

In addition, the steel sheet contains, in weight percent, carbon (C): 0.05-0.30%, manganese (Mn): 1.0-3.0%, phosphorus (P): 0.10% or less, sulfur (S): 0.01% or less, aluminum ( Al): 0.01 to 0.1%, nitrogen (N): 0.008% or less, and may further contain residual Fe and unavoidable impurities.

Silicon (Si) is an important element that contributes to the improvement of strength through solid solution strengthening, and plays a role in improving strength while suppressing deterioration of processability. If the Si content exceeds 0.7%, there is a problem in that Si oxide in the form of a layer is formed directly under the Fe oxide layer, resulting in poor adhesion. More advantageously, it is more preferably 0.5% or less (excluding 0).

Carbon (C) is an element effective in securing the strength of steel, and can be contained in an amount of 0.05% or more. However, if the content exceeds 0.30%, there is a risk that the weldability of the steel may deteriorate.

Manganese (Mn) contributes to the improvement of strength through solid solution strengthening and is an element that improves the hardenability of the austenite phase, effectively contributing to stabilization of strength. In order to stably obtain the intended strength, it is preferable to include Mn in an amount of 1.0% or more. However, if the content exceeds 3.0%, there is a problem that processability is deteriorated. Therefore, the Mn is preferably contained in an amount of 1.0 to 3.0%, and more advantageously, it is preferably contained in an amount of 1.5 to 2.5%.

Aluminum (Al) is an element added for the deoxidation effect, and if its content is less than 0.01%, the deoxidation effect cannot be sufficiently secured. On the other hand, if the content exceeds 0.1%, there is a problem of the formation of internal oxides due to Al.

Phosphorus (P), sulfur (S), and nitrogen (N) are elements that are inevitably added during the steel manufacturing process, and it is advantageous to control their contents as low as possible. In the present invention, there is no difficulty in securing the intended physical properties when P is included at 0.10% or less, S is at 0.01% or less, and N is at 0.008% or less.

The above-described base steel plate may be a cold-rolled steel plate that can be used as a material for automobiles, especially as a material for structural members, and may have a thickness of 1.0 to 1.8 mm.

Below, a method for manufacturing a high-strength hot-dip galvanized steel sheet with excellent plating adhesion, which is another aspect of the present invention, will be described in detail. However, it is necessary to note that the hot-dip galvanized steel sheet of the present invention does not necessarily have to be manufactured according to the following embodiment, but the following embodiment is one preferred method of manufacturing the hot-dip galvanized steel sheet of the present invention.

First, prepare a base steel plate.

The base steel plate has the alloy composition as mentioned above and may be a cold-rolled steel plate with a certain thickness, for example, 1.0 to 1.8 mm.

A hot-dip galvanized steel sheet can be manufactured by annealing and heat-treating the base steel sheet and then immersing it in a molten zinc plating bath.

Generally, when a base steel sheet is annealed and heat treated, Si, Mn, etc. in the steel tend to diffuse to the surface and thicken the surface.

To prevent this, the present invention has the feature of suppressing the diffusion of the elements to the surface of the steel sheet during the heat treatment process by forming an Fe oxide layer at the beginning of the heat treatment under specific conditions when annealing the steel sheet.

The annealing heat treatment step may be performed by charging the cold-rolled steel sheet into an annealing furnace and then heat-treating it to a specific temperature.

In particular, in the present invention, a first heat treatment step of heating to 550 to 700 ° C. while supplying oxygen into an annealing furnace into which the cold-rolled steel sheet is charged and a second heat treatment step of heating to 700 to 850 ° C. in a nitrogen reduction atmosphere can be performed. In the first heat treatment step, an Fe oxide layer may be formed on the surface of the cold rolled steel sheet.

The Fe oxide layer formed in the first heat treatment step is formed as Fe in the steel is oxidized, and the formed Fe oxide layer serves to suppress diffusion of oxidizing elements such as Si and Mn in the steel to the surface of the steel sheet during the heat treatment process.

It should be noted that this Fe oxide layer can be formed by supplying excess oxygen in the annealing furnace, but is not limited to this.

Preferably, in the present invention, the oxygen concentration (ppm), oxygen supply temperature (°C), and line speed (L/S, mpm) are controlled so that the thickness of the Fe oxide layer, calculated by the following formula (1), is 50 to 250 nm. It is characterized by More advantageously, the thickness of the Fe oxide layer is more preferably 100-150 nm.

Equation (1)

Thickness of Fe oxide layer (nm) = -26.5 + (0.08 × oxygen concentration (ppm)) + (0.11 × oxygen supply temperature (℃)) - (0.28 × L/S (mpm))

That is, the present invention forms an Fe oxide layer by supplying oxygen in the first heat treatment step by controlling the concentration of oxygen injected, the temperature at which oxygen is supplied, and the line speed (L/S) of the annealing furnace. It is possible to form an Fe oxide layer with an optimal thickness of 50 to 250 nm. At this time, the value of equation (1) is a theoretical value and may differ to a certain extent from the actual measured value of the Fe oxide layer formed by the primary heat treatment. In the present invention, if the difference is around 10 nm, it is stated that the Fe oxide layer has been formed at the intended level.

More preferably, the oxygen concentration injected in the first heat treatment step is controlled in the range of 500 to 1000 ppm, the oxygen supply temperature is controlled to 550 to 700 ° C., and the line speed (L/S) is controlled to the range of 60 to 100 mpm. Here, line speed refers to the speed at which the cold rolled steel sheet charged into the annealing furnace passes through the furnace.

If the oxygen concentration is less than 500 ppm, it takes a long time to form an Fe oxide layer of sufficient thickness, which reduces economic efficiency, and there is a risk that oxidizing elements in the steel may diffuse to the surface due to long-term heat treatment. On the other hand, if the concentration exceeds 1000 ppm, there is a risk that the Fe oxide layer may be formed too thick.

If the oxygen supply temperature is less than 550°C, even if a sufficient amount of oxygen is supplied, oxidation of Fe in the steel will not occur properly, and there is a risk that surface enrichment of Si, Mn, etc. cannot be effectively suppressed during the subsequent reduction annealing process. On the other hand, if the temperature exceeds 700°C, the thickness of the Fe oxide layer becomes excessively thick, and there is a risk that the Fe oxide layer may not be completely reduced during the subsequent reduction annealing process and the plating layer may be peeled off by the remaining Fe oxide.

If the line speed is less than 60 mpm, the time for the first heat treatment becomes longer and productivity decreases. On the other hand, if the line speed exceeds 100 mpm, the Fe oxide layer cannot be formed to a sufficient thickness.

If the thickness of the Fe oxide layer according to the above equation (1) is less than 50 nm, it is difficult to effectively suppress surface diffusion of oxidizing elements in the steel by the Fe oxide layer. On the other hand, if the thickness exceeds 250 nm, it takes a long time to reduce the Fe oxide layer in the subsequent reduction heat treatment process, which reduces productivity, and there is a problem that plating peeling occurs due to the remaining Fe oxide that cannot be completely reduced. .

After performing the first heat treatment according to the above to form the Fe oxide layer to a sufficient thickness, the annealing heat treatment process can be completed through subsequent heat treatment. At this time, the subsequent heat treatment is a process of heating the first heat-treated cold-rolled steel sheet to a temperature of 700 to 850°C, and in this process, the Fe oxide layer formed during the first heat treatment can be reduced.

In order to reduce the Fe oxide layer, the second heat treatment is preferably performed in a nitrogen reducing atmosphere, and more specifically, the heat treatment is performed in an atmosphere composed of 3 to 10% by volume of hydrogen (H ₂ ) and the balance nitrogen (N ₂ ). It is desirable.

If the temperature during the second heat treatment is less than 700°C, there is a risk that the recrystallization effect may be insufficient, and the Fe oxide layer may not be sufficiently reduced, so there is a risk of plating peeling due to residual Fe oxide. On the other hand, if the temperature exceeds 850°C, the surface concentration of oxidizing elements in the steel is promoted, and surface oxides increase, which poses a risk of plating peeling.

A hot-dip galvanizing process can be performed by immersing the cold-rolled steel sheet on which annealing heat treatment has been completed according to the above into a plating bath, and the hot-dip galvanized steel sheet obtained by the hot-dip galvanizing process can be subjected to an alloying heat treatment process as a subsequent process, if necessary. .

Since the above hot-dip galvanizing process can be performed under normal conditions, the conditions are not particularly limited. However, it should be noted that for effective plating, it can be performed in a hot-dip galvanizing bath at 440-460°C.

A hot-dip galvanized steel sheet can be obtained by going through the series of processes described above. The hot-dip galvanized steel sheet of the present invention effectively suppresses surface diffusion of oxidizing elements such as Si and Mn in the steel during the manufacturing process, and improves plating adhesion by intermittently forming the shape of the oxide formed immediately below the interface between the plating layer and the base steel sheet. It has this excellent feature.

Meanwhile, the cold rolled steel sheet of the present invention can be manufactured by heating a steel slab and then cold rolling a hot rolled steel sheet manufactured by hot rolling at a certain reduction rate.

At this time, heating, hot rolling, and cold rolling of the steel slab may be performed according to conditions commonly used in the technical field. Although it is not limited to this, as an example, the steel slab may be heated at a temperature range of 1100 to 1300°C, and then finish hot rolling may be performed at a finish rolling temperature of 800 to 1000°C. Thereafter, cold rolling can be performed by setting the cold rolling reduction rate according to the intended thickness.

It should be noted that a coiling process may be additionally performed on the hot rolled steel sheet obtained through the hot rolling, and a pickling process may be further performed to remove scale formed on the surface of the hot rolled steel sheet before the cold rolling.

Hereinafter, the present invention will be described in more detail through examples. However, it should be noted that the following examples are only for illustrating and embodying the present invention and are not intended to limit the scope of the present invention. This is because the scope of rights of the present invention is determined by matters stated in the patent claims and matters reasonably inferred therefrom.

(Example)

Invention Examples 1 to 4 and Comparative Examples 1 to 7

A cold-rolled steel sheet with a thickness of 1.2 mm containing Si and Mn in the amounts shown in Table 1 below was prepared (other composition: 0.083%C, 0.022%P, 0.0034%S, 0.03%Al, 0.0045%N, the balance Fe and inevitable impurities). Thereafter, each cold-rolled steel sheet was charged into an annealing furnace, and then first heat treatment was performed according to the conditions shown in Table 1 below. After forming an Fe oxide layer of a certain thickness on the surface of the cold rolled steel sheet through the first heat treatment, the second heat treatment was performed by heating to 800°C in a nitrogen reduction atmosphere containing 5% by volume of H ₂ .

A hot-dip galvanized steel sheet was manufactured by immersing the cold-rolled steel sheet on which the annealing heat treatment as described above was completed in a hot-dip galvanizing bath at 460°C.

Assessment Methods

In order to evaluate the plating adhesion of each hot-dip galvanized steel sheet manufactured according to the above, each hot-dip galvanized steel sheet was cut to a size of 30 mm × 80 mm to produce a specimen, and then a structural adhesive was applied to the specimen and incubated at 170°C. It was cured in an oven for 20 minutes. Thereafter, the specimen was bent at 90° by holding it in a bending jig, and then it was visually confirmed whether the plating layer was attached to the structural adhesive to evaluate whether plating adhesion was good or whether the plating layer was peeling.

In addition, in order to measure the amount of Si concentrated in the steel during the heat treatment process, each cold-rolled steel sheet on which the second heat treatment was completed was observed through Glow Discharge Optical Emission Spectrometry (GDS). Specifically, the profile was measured from the surface of each cold rolled steel sheet to a depth of 1㎛ in the thickness direction, and then the integral value and peak maximum concentration value were measured up to a depth of 0.1㎛.

In addition, the thickness of the Fe oxide layer formed in the first heat treatment process was measured through Glow Discharge Optical Emission Spectrometry (GDS), and the depth at which the oxygen profile converges to 0 was defined as the thickness of the Fe oxide layer. .

Each of the above results is shown in Table 1 below.

division Alloy composition (% by weight) First heat treatment GDS Plated
Adhesion Si Mn Oxygen
density
(ppm) Oxygen supply temperature
(℃) line
speed
(mpm) Fe oxide layer thickness
(nm) Equation (1) Si concentration
integral value
(%㎛) Si concentration
maximum value
(%) Invention Example 1 0.2 1.69 1000 600 60 94.9 102.7 0.049 0.95 Good Invention Example 2 0.5 1.75 750 650 80 80.5 82.6 0.097 1.82 Good Invention Example 3 0.3 1.70 500 650 60 69.0 68.2 0.072 1.55 Good Invention Example 4 0.25 1.77 1000 650 60 114.9 108.2 0.055 1.03 Good Comparative Example 1 0.75 1.71 1000 600 100 84.8 91.5 0.177 3.51 peeling Comparative Example 2 0.72 1.65 750 650 60 83.7 88.2 0.181 3.58 peeling Comparative Example 3 0.82 1.72 350 600 60 42.2 50.7 0.255 4.05 peeling Comparative Example 4 1.21 1.66 300 600 100 29.1 35.5 0.326 4.89 peeling Comparative Example 5 0.3 1.70 150 510 90 15.3 16.4 0.699 10.02 peeling Comparative Example 6 0.25 1.72 100 500 60 18.5 19.7 0.633 9.83 peeling Comparative Example 7 0.2 1.75 200 600 60 31.6 38.7 0.301 4.58 peeling

As shown in Table 1, the alloy composition proposed in the present invention, especially the Si content in the steel, is 0.7% or less, and the first heat treatment process in the annealing heat treatment process is performed under conditions that satisfy Equation (1). 4 showed that the concentration of Si was minimized and plating adhesion was improved.

On the other hand, in Comparative Examples 1 and 2, where the Si content in the steel exceeds 0.7%, Si surface enrichment was not suppressed during the annealing heat treatment, and Si and Mn oxides formed directly under the Fe oxide layer were formed in the form of a layer. As a result, plating peeling was caused.

In the case of Comparative Examples 3 and 4, in the process of forming the Fe oxide layer, Si and Mn oxides in the form of a layer are formed at the interface between the oxide layer and the steel sheet, and these oxides act as a barrier, leading to the growth of the Fe oxide layer. was suppressed. As a result, plating adhesion deteriorated.

On the other hand, in Comparative Examples 5 to 7, which did not satisfy Equation (1) during the first heat treatment, Fe oxide was formed quite thinly during the first heat treatment, and as a result, excess Si and Mn were concentrated on the steel surface to form surface oxides. As a result, plating peeling occurred.

Figure 1 is a GDS measurement result, which is a depth profile measuring the distribution of each element in the thickness direction from the surface, and it is possible to check whether the Si concentration peaks.

Figure 1(a) is the result of Invention Example 1, and Figure 1(b) is the result of Comparative Example 1. In the case of Comparative Example 1, it can be seen that the concentration of Si increases to approximately 40% within a depth of 0.1 μm from the surface, while in Inventive Example 1, it is maintained at approximately 10% or less.

Figure 2 shows the results of measuring the distribution of each element directly below the interface between the plating layer of the hot-dip galvanized steel sheet and the base steel sheet using TEM-EDS.

Figure 2(a) is the result of Invention Example 1, and Figure 2(b) is the result of Comparative Example 1. In the case of Comparative Example 1, it can be confirmed that Mn and Si exist continuously parallel to the rolling direction directly below the interface. This means that Mn and Si oxides are continuously formed directly below the interface. In contrast, in Inventive Example 1, it can be confirmed that Si and Mn intermittently exist directly below the interface, which means that the surface diffusion of Si and Mn in the steel is suppressed compared to Comparative Example 1.

Claims (8)

A base steel sheet containing 0.7% or less (excluding 0%) of silicon (Si) by weight; And a hot-dip galvanized steel sheet including a hot-dip zinc-based plating layer formed on at least one surface of the base steel sheet,
High-strength hot-dip galvanizing with excellent plating adhesion, characterized in that the Si concentration integral value of the GDS profile measured from the interface between the base steel sheet and the plating layer to a depth of 0.1㎛ in the thickness direction of the base steel sheet is 0.1%·㎛ or less (excluding 0). Steel plate.
According to clause 1,
High-strength hot-dip galvanizing with excellent plating adhesion with a peak maximum concentration of Si element of 2% or less (excluding 0) in the GDS profile measured from the interface between the base steel sheet and the plating layer to a depth of 0.1㎛ in the thickness direction of the base steel sheet. Steel plate.
According to clause 1,
The base steel plate contains, in weight percent, carbon (C): 0.05 to 0.30%, manganese (Mn): 1.0 to 3.0%, phosphorus (P): 0.10% or less, sulfur (S): 0.01% or less, and aluminum (Al). : 0.01~0.1%, nitrogen (N): 0.008% or less, high-strength hot-dip galvanized steel sheet with excellent plating adhesion, further containing the remaining Fe and inevitable impurities.
According to clause 1,
The base steel sheet is a high-strength hot-dip galvanized steel sheet with excellent plating adhesion, which is a cold-rolled steel sheet with a thickness of 1.0 to 1.8 mm.
Preparing a cold-rolled steel sheet using a base steel sheet containing 0.7% or less (excluding 0%) of silicon (Si) by weight; Annealing and heat treating the cold rolled steel sheet; And manufacturing a hot-dip galvanized steel sheet by immersing the annealed heat-treated cold-rolled steel sheet in a hot-dip galvanizing bath,
The annealing heat treatment step consists of a first heat treatment step of heating to 550 to 700° C. while supplying oxygen into an annealing furnace into which the cold rolled steel sheet is charged, and a second heat treatment step of heating to 700 to 850° C. in a nitrogen reduction atmosphere. ,
In the first heat treatment step, an Fe oxide layer is formed, and the oxygen concentration (ppm), oxygen supply temperature (°C), and line speed (L/S, A method of manufacturing high-strength hot-dip galvanized steel sheet with excellent plating adhesion, characterized by controlling mpm).

Equation (1)
Thickness of Fe oxide layer (nm) = -26.5 + (0.08 × oxygen concentration (ppm)) + (0.11 × oxygen supply temperature (℃)) - (0.28 × L/S (mpm))
According to clause 5,
A method of manufacturing a high-strength hot-dip galvanized steel sheet with excellent plating adhesion, wherein the oxygen concentration is controlled to 500 to 1000 ppm, the oxygen supply temperature is controlled to 550 to 700 ° C., and the line speed is controlled to 60 to 100 mpm.
According to clause 5,
The steel sheet contains, in weight percent, carbon (C): 0.05 to 0.30%, manganese (Mn): 1.0 to 3.0%, phosphorus (P): 0.10% or less, sulfur (S): 0.01% or less, and aluminum (Al). : 0.01~0.1%, nitrogen (N): 0.008% or less, a method of manufacturing a high-strength hot-dip galvanized steel sheet with excellent plating adhesion, further containing the remaining Fe and unavoidable impurities.
According to clause 5,
A method of manufacturing a high-strength hot-dip galvanized steel sheet with excellent plating adhesion, wherein the step of manufacturing the hot-dip galvanized steel sheet is performed in a hot-dip galvanizing bath at 440 to 460 ° C.