JPH059694A - Galvannealed steel sheet - Google Patents

Abstract

PURPOSE:To improve the adhesion of the galvannealed steel sheet. CONSTITUTION:The galvannealed steel sheet which is made of a base material having the following compsn. and is formed thereon with the plating layer having the following compsn. is prepd. Namely, the compsn. of the above- mentioned base material contains, by weight%, <=0.008% C, over 0.05% to 0.25% Si, over 0.08% to 0.7% Mn, <=0.075% P, <=0.02% S, <=0.005% N, over 0.005% to 0.05% Al, and further contains over 0.04% to 0.2% Ti, or over 0.4% to 0.2% Ti and <=0.02% Nb and consists of the balance Fe and unavoidable impurities and satisfies Ti(%)>P(%). The comps. of the above-mentioned plating layer contains 8 to 15% Fe, consists of the balance Zn, Al and unavoidable impurities and satisfies Al(%)=[(0.20 to 0.50)/100]XZn(%).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloyed hot dip galvanized steel sheet used for coated steel sheets for home appliances, painted steel sheets for automobiles, etc. Regarding steel plates.

[0002]

2. Description of the Related Art A galvannealed steel sheet is a steel sheet that has been galvanized and then heated to cause mutual diffusion between the Zn phase on the surface of the plating layer and the steel sheet that is the base material. The whole layer is made of Fe-Zn alloy. This alloyed hot dip Zn plated steel sheet is excellent in paintability, corrosion resistance, weldability, economy and the like, and has been widely used in the industrial fields of home appliances, automobiles and building materials in recent years.

Usually, the alloying treatment is performed by heating a steel sheet which has been subjected to continuous hot dip Zn plating in a heat treatment furnace for alloying to a material temperature of 500 to 600 ° C. for 3 to 30 seconds.

Further, the steel sheet before the hot dip Zn plating is preheated, is annealed in a reducing atmosphere of H ₂ + N ₂ and under a temperature condition depending on the material, and is exposed to the atmosphere until the hot dip Zn plating is applied. Without being cooled to around the bath temperature of the plating bath.

The plating layer of alloyed hot dip Zn plated steel sheet is Fe-
It consists of an intermetallic compound of Zn, and its Fe concentration is usually 8-12.
% By weight. The amount of plating adhered is usually 25 to 70 g / m ² per side. Adhesion amount is 25 g /
It is difficult to reduce the amount to m ² or less, and if the adhesion amount is 70 g / m ² or more, the powdering resistance of the plating layer deteriorates.

The plating layer usually contains 0.12 to 0.2% by weight of Al. There are two reasons for this. One of them is that the production facilities for alloyed hot dip galvanized steel sheet and normal hot dip galvanized steel sheet are often the same, so Al added in the Zn bath when producing the normal hot dip galvanized steel sheet is alloyed. This is because they are inevitably mixed in when producing a chemical-melting Zn-plated steel sheet.
The purpose of adding Al in the production of ordinary hot-dip Zn plated steel sheet is that the workability of the alloy phase formed at the interface between the plating layer and the base steel sheet (hereinafter simply referred to as "interface") is poor,
This is to suppress the formation of this alloy phase and ensure the workability of the plating layer.

Another reason is that the powdering resistance of the coating layer of the alloyed hot dip galvanized steel sheet is ensured and the alloyed hot dip galvanized steel sheet has a dross defect (which is
The Fe-Zn alloy adheres to the surface of the steel sheet in the form of sand grains and is pressed by a sink roll. ) Is generated, 0.08 to 0.11% by weight of Al is added to the Zn bath when the alloyed hot dip Zn plated steel sheet is manufactured.
This is because plating is applied. Al tends to be enriched in the plating layer, and molten Zn is melted in a Zn bath with an Al concentration of 0.08 to 0.11% by weight.
If plating is applied, the Al concentration in the plating layer will be 0.12 to 0.2% by weight.

Conventionally, low carbon Al-killed steel has often been used as a base material for alloyed hot-dip galvanized steel sheets.
In recent years, as the use of alloyed hot dip Zn plated steel sheets has expanded, its deep drawability has been required, and IF steel (Interstit
The use of ultra low carbon steel called ial free steel) is increasing. IF steel contains T, which is an inevitable interstitial solid solution element such as N and C.
It is an ultra-low carbon alloy steel fixed with an alloying element such as i or Nb, and is a non-aging and highly workable material. I
When F steel is used as the base material, C <0.003%, Si <0.04%, M
n: 0.12-0.30%, P: 0.01-0.02%, S: 0.008-0.0
2%, N <0.04%, Al: 0.02-0.05%, Ti: 0.02-0.06
%, Nb <0.015% is widely used. Note that Nb may not be added in some cases.

A high-strength steel sheet is used as a base material for the alloyed hot-dip Zn-plated steel sheet which requires strength. At the same time, when high formability is required, C <0.003%, Si <0.04
%, Mn: 0.3 to 1.0%, P: 0.025 to 0.08%, S: 0.0
08-0.02%, N <0.04%, Al: 0.02-0.05%, Ti: 0.02
A material having a composition of ˜0.06% and Nb <0.015% is usually adopted.

In the alloyed hot-dip galvanized steel sheet produced by the above-mentioned production method and comprising the above-mentioned base material and the plating layer, since the plating layer is an intermetallic compound, the adhesion of the plating layer at the interface is low. There is a drawback that. That is,
Since the plating layer is an intermetallic compound lacking in deformability, when a shearing force acts on the plating layer, peeling easily occurs at the interface.
In particular, when the alloyed hot-dip Zn-coated steel sheet after coating is subjected to shocking deformation or shearing, it is easy to peel at the interface. Also, by joining the alloyed hot dip Zn plated steel sheet with an adhesive,
When a peeling test is carried out, the peeling often occurs not at the interface between the adhesive and the plating layer but at the interface between the plating layer and the base steel sheet (the latter interface is simply referred to as “interface” in this specification).

In the case of an electroplated steel sheet such as Ni-Zn or Fe-Zn, the adhesion of the plating layer at the interface is low because the plating layer is an intermetallic compound. It is known that this problem can be solved by performing underlayer plating (strike) of Fe, Fe or the like. However, in the case of alloyed hot dip Zn plated steel sheet, there is no suitable solution.

Factors causing the peeling of the plating layer at the interface include not only the true interfacial adhesion strength governed by the consistency of different phase interfaces and the interfacial energy, but also the geometric shape of the interface and the plating layer and the substrate. Mechanical properties and physical constants (eg elastic modulus)
Etc. are possible. Therefore, in order to obtain an alloyed hot-dip galvanized steel sheet with excellent adhesion and deep drawability, measures should be taken from the viewpoint of modifying the plating layer, optimizing the geometrical shape of the interface, optimizing the base material, etc. Need to consider.

In order to improve the adhesion of the alloyed hot-dip galvanized steel sheet, the present inventors increased the Al concentration with respect to the Zn concentration in the Zn-plated layer to 0.30 to 0.50%.
Invented a plated steel sheet and applied for a patent first (Japanese Patent Application No. 3-908).
No.) Although the adhesion of this alloyed hot dip Zn plated steel sheet has been improved considerably, it is practically insufficient when accompanied by shocking deformation or shearing such as deep drawing.

JP-A-64-68456 discloses that the coating weight of the plating layer is 45 to 90 g / m ³ , the Fe concentration is high and the Γ phase of the brittle interface has a thickness of 1.0 μm or less, and the Fe concentration is Disclosed is a galvannealed steel sheet having a plated layer having a low η phase and a relatively soft ζ phase that are not present on the surface of the plated layer. However, even in the case of this galvannealed steel sheet, the adhesion under severe conditions is not practically sufficient.

[0015]

As described above, in the galvannealed steel sheet, since the plating layer is an intermetallic compound, there is a drawback that the adhesion of the plating layer at the interface is low. On the other hand, alloyed hot-dip Zn plated steel sheet is excellent in paintability, corrosion resistance, weldability, economy, etc., and therefore its demand is increasing in the industrial fields of home appliances, automobiles and building materials, and at the same time shock deformation or shearing is required. Applications under severer conditions than before, such as applications involving processing or applications involving joining with an adhesive, are expanding. Therefore, the adhesiveness of the plated layer of the alloyed hot dip Zn plated steel sheet is increasingly required. That is, there is an urgent need to improve the adhesiveness at the interface.

An object of the present invention is to provide an alloyed hot-dip Zn plated steel sheet which is extremely excellent in the adhesion of the plating layer, that is, the adhesion at the interface.

[0017]

Means for Solving the Problems The subject matter of the present invention is the following galvannealed steel sheet.

The composition of the steel sheet used as the base material is, by weight%, C: 0.008% or less, Si: more than 0.05% to 0.
25% Mn: more than 0.08% to 0.7%, P: 0.075% or less, S: 0.02% or less, N: 0.005% or less, Al: more than 0.005% to 0.05%, Ti: more than 0.04% to 0.2% or Ti: more than 0.04% to 0.2% and Nb: 0.02% or less, the balance consisting of Fe and unavoidable impurities, and Ti (%)> P (%) is satisfied. The composition of the plating layer to be formed on the alloy contains Fe: 8 to 15% by weight and the balance is Zn, Al and inevitable impurities.
In addition, alloyed molten Zn with excellent adhesion characterized by satisfying Al (%) = [(0.20 to 0.50) / 100] x Zn (%)
Plated steel sheet.

The steel sheet used as a base material is an alloyed hot-dip Zn plated steel sheet which, in addition to the above composition, further contains B in an amount of 20 ppm or less and which has excellent adhesion as described above.

According to the method of the present invention, after the steel sheet is annealed, it is melted in a molten Zn bath containing Al without exposing it to the outside air.
It is premised that the Zn plating treatment is performed and then the alloying treatment is performed.

[0021]

[Function] In order to improve the adhesion at the interface of the alloyed hot dip Zn plated steel sheet, the Fe-Zn reaction in the ferrite crystal grains is suppressed, and the Fe-Zn reaction in the ferrite crystal grain boundaries is relatively suppressed. It is effective to promote.

Specific means for accelerating the Fe-Zn reaction at the ferrite grain boundaries are as follows: (1) Surface concentration of easily oxidizable elements (Si, Mn, etc.) due to oxidation in the range where no plating occurs Promote as much as possible within.

(2) Increase the Al concentration in the plating layer.

It is conceivable that

When promoting the surface concentration of easily oxidizable elements (Si, Mn, etc.), surface concentration of Si in the base steel sheet by oxidation is particularly effective. In particular, when a Ti-added steel having a high annealing temperature is used as a base material, it is effective to use a Ti-added steel positively containing Si within a range not impairing the plating property.

The reason why the composition of the base steel sheet and the composition of the plating layer in the alloyed hot-dip galvanized steel sheet of the present invention are limited as described above will be described below.

(1) Composition of base steel sheet 1) C: 0.008% or less Since C is an element having an adverse effect on deep drawability, it is desirable that the C content be small. The content of C is 0.008% in order to suppress the precipitation of C in the ferrite crystal grain boundaries and to enhance the cleanliness of the ferrite crystal grain boundaries to ensure good deep drawability.
Below. If the C content exceeds 0.008%, a large amount of Ti must be added to fix C.

2) Si: more than 0.05% and 0.25% or less Si is conventionally considered to be an element that causes non-plating in the hot dip Zn plating of a thin plate. However, the dew point in the annealing atmosphere was -35 ° C or lower, and the Al concentration in the Zn bath was 0.
If it is 12% or more, no serious harm will occur. The galvannealed steel sheet of the present invention positively contains Si. Si is concentrated as an oxide on the surface of the steel sheet during the annealing process. Particularly, in the case of Ti-added steel whose annealing temperature is usually 800 ° C or higher, the concentration of Si is remarkable. If the Si content is 0.05% or less, the concentration of Si on the surface of the steel sheet will be insufficient. If the concentration of Si is insufficient, not only the Fe-Zn reaction in the ferrite crystal grains is not sufficiently suppressed but also the Fe-Zn at the ferrite grain boundaries.
The reaction is not promoted. That is, the adhesion at the interface becomes insufficient. Therefore, the Si content is more than 0.05%. On the other hand, if the Si content exceeds 0.25%, it causes non-plating in hot dip Zn plating. Therefore, the Si content is 0.25% or less.

3) Mn: more than 0.08% and 0.7% or less Mn has the effect of fixing S contained as an impurity in the steel as MnS and improving the formability (r value) of the steel sheet. However, if the Mn content is 0.08% or less, the above-mentioned effects cannot be sufficiently obtained. Therefore, the Mn content is set to more than 0.08%. On the other hand, if the Mn content exceeds 0.7%, the formability of the steel sheet remarkably decreases, so the Mn content is set to 0.7% or less. Note that Mn, like Si, is concentrated as an oxide on the surface of the steel sheet in the annealing step, so that the Mn content is preferably large within the above range in order to improve the adhesion at the interface. However, its effect is smaller than that of Si.

4) P: 0.075% or less P is effective in improving the strength of the steel sheet, and is an indispensable element in the case of the base material of the alloyed hot dip Zn plated steel sheet for high strength. However, P has the adverse effect of suppressing the Fe-Zn reaction at the ferrite grain boundaries, so if the P content is greater than the Ti content, the adhesion at the interface is reduced. Therefore, the Ti content (%)> P content (%) is set. Further, when the P content exceeds 0.075%, the alloying reaction is significantly suppressed, so the P content is set to 0.075% or less.

5) S: 0.02% or less S bonds with Ti to form TiS and consumes solid solution Ti that fixes C. If the S content exceeds 0.02%, the non-aging property and workability of the alloyed hot dip Zn plated steel sheet deteriorate, so the S content is set to 0.02% or less.

6) N: 0.005% or less N, like S, combines with Ti to form TiN and consumes solid solution Ti that fixes C. If the N content exceeds 0.005%, the non-aging property and workability of the alloyed hot dip Zn plated steel sheet deteriorate, so the N content is set to 0.005% or less.

7) Al: over 0.005% and 0.05% or less Al is effective and indispensable for deoxidizing steel. If the Al content is 0.005% or less, deoxidation will be insufficient, so the Al content should exceed 0.005%. On the other hand, the Al content is 0.05%
If it exceeds 0.1%, the manufacturing cost of the steel sheet increases, so the Al content is made 0.05% or less.

8) Ti: more than 0.04% and 0.2% or less Ti fixes C, S and N, which are contained in the steel in a trace amount, to improve the cleanliness of ferrite grain boundaries and increase the r value. , Improve the formability of steel sheet. Further, the improvement of the cleanliness of the ferrite crystal grain boundaries has the effect of promoting the Fe-Zn reaction at the ferrite crystal grain boundaries. Furthermore, Ti raises the recrystallization temperature and promotes the concentration of easily oxidizable elements on the surface of the steel sheet in the annealing step. That is, the adhesion at the interface is improved. If the Ti content is 0.04% or less, the above effect is not sufficient, so the Ti content is set to an amount exceeding 0.04%. on the other hand,
If the Ti content exceeds 0.2%, the manufacturing cost of steel sheet will increase, so the Ti content should be 0.2% or less.

One of the base materials of the alloyed hot-dip galvanized steel sheet of the present invention is one in which, in addition to the above alloy elements, the balance is Fe and inevitable impurities.

Another base material of the galvannealed steel sheet of the present invention contains Nb in addition to the above alloy components. 9) Nb: 0.02% or less Nb has the effect of improving the anisotropy of the formability (r value) of the steel sheet, so it may be added if necessary. However, if the Nb content exceeds 0.02%, not only the cleanliness of the ferrite grain boundaries decreases but also the manufacturing cost of the steel sheet increases. Therefore, when Nb is added, its content should be 0.02% or less.

Yet another base material of the alloyed hot-dip galvanized steel sheet of the present invention contains B in addition to the above alloy components. 10) B: 20 ppm or less B has the effect of improving the hardenability of steel and increasing the strength by adding an extremely small amount. However, the B content is 20 ppm
If over B, workability and weldability are impaired, so when B is added, its content should be 20 ppm or less.

(2) Composition of plating layer 1) Fe: 8% or more and 15% or less Fe in the plating layer is Fe flowing from the base steel sheet by the alloying treatment after the hot dip Zn plating. The higher the Fe content in the plating layer, the better the adhesion at the interface. When the Fe content is less than 8%, the residual amount of the η phase (unalloyed pure Zn phase) increases and the weldability and paintability deteriorate. Therefore, the Fe content is set to 8% or more. On the other hand, when the Fe content exceeds 15%, the powdering resistance of the plating layer is significantly reduced. Therefore, Fe
Content should be 15% or less. Incidentally, in the alloyed hot-dip galvanized steel sheet of the present invention in which the Al content in the plating layer is high, the adhesion at the interface is considerably high even when the Fe content is 8%.

2) Al (%) = [(0.20 to 0.50) / 100] × Zn (%) Al improves the geometrical shape of the interface between the plating layer and the base steel sheet, and improves the adhesion at the interface. Has the effect of increasing. This is Al
It is considered that this is due to the promotion of the Fe-Zn reaction at the ferrite grain boundaries. Also, Al has the effect of improving the mechanical properties of the alloy phase. However, when Al is less than 0.20% of Zn, even if the steel sheet having the above composition is used as the base steel sheet, Al is
The effect of promoting the Fe-Zn reaction at the ferrite grain boundaries is not sufficient, and the adhesion at the interface is reduced. In particular, when the alloyed hot-dip Zn-coated steel sheet after coating is subjected to shock deformation or joined with an adhesive, peeling easily occurs at the interface. Therefore, Al is 0.20% or more of Zn. On the other hand, Al
The higher the concentration, the better the adhesion at the interface, but Al
If it exceeds 0.50%, it causes variation in alloying treatment speed. Variations in the alloying treatment rate cause macroscopic unevenness on the surface of the alloyed hot-dip galvanized steel sheet, deteriorating the appearance quality of the surface and significantly reducing the commercial value. This tendency is particularly remarkable when the base steel sheet is an ultra-low carbon IF steel. Therefore, Al is 0.50% or less of Zn.

The plated layer of the alloyed hot-dip Zn plated steel sheet according to the present invention comprises the above alloy elements and the balance Zn and inevitable impurities.

The galvannealed steel sheet of the present invention comprises:
For example, it can be manufactured by the following method.

The steel sheet having the above composition is preheated in an oxidation-free furnace, a direct-fire reduction furnace, or a reducing atmosphere. In preheating,
When iron oxide is generated on the surface of the steel sheet, it causes a decrease in adhesion strength at the interface, so it is desirable to suppress the generation of iron oxide as much as possible. Then, in a reducing atmosphere with a dew point of −35 ° C. or less, the Al concentration is 0.13 to 0.21 in a state of being annealed to the steel plate temperature range of 810 to 880 ° C. and cooled to the steel plate temperature of 470 to 580 ° C. without exposing to the atmosphere. %, The bath temperature is 475 to 495 ℃, and the molten Zn plating is conducted by introducing it into the molten Zn bath. Due to the Al enrichment phenomenon, the Al concentration in the plating layer is in the range of 0.20 to 0.50% of Zn. After the hot dip Zn plating is applied, the hot dip Zn plated steel sheet is heated in a heat treatment furnace so that the Fe content in the plating layer is 8-15% by weight.
Alloying treatment is performed so that This alloying process is 3
It is carried out at a temperature of 00 ° C or higher, but it is desirable to carry out the treatment at a temperature of 480 to 530 ° C because continuous treatment is difficult when the alloying treatment temperature is low. A longer heat treatment time gives more desirable product characteristics (adhesion at the interface). The reason for this is not clear, but as the heat treatment time increases, the mechanical properties of the alloyed layer near the interface are improved, and the Fe-Zn reaction at the ferrite grain boundaries increases and the anchoring effect also increases. Conceivable. The alloyed hot-dip Zn plated steel sheet of the present invention obtained by the above production method has extremely large shear peel strength at the interface.

At present, in order to improve the friction characteristics and electrodeposition coatability of the alloyed hot dip Zn plated steel sheet, it is used as the upper layer of the Zn plating layer.
It is widely practiced to apply Fe-based or Zn-Ni plating, and the upper layer plating can be applied to the alloyed hot-dip Zn plated steel sheet of the present invention.

The above-mentioned manufacturing method is effective when a very high interfacial shear peel strength is required for practical use. However, the galvannealed steel sheet of the present invention may be manufactured by a method other than the above.

[0045]

[Examples] Cold-rolled steel sheet (sheet thickness 0.8 mm) made of an ultra-low carbon steel having the composition shown in Table 1-1, Table 1-2 and Table 1-3
The unannealed material was cut into a size of 250 × 100 mm to be used as a base material for the alloyed hot-dip galvanized steel sheet, and used as a test material.

These test materials were degreased and washed with a NaOH solution at 75 ° C., and then annealed for 60 seconds in an atmosphere having a dew point of −40 ° C. and an atmospheric gas of N ₂ + 26% H ₂ (atmosphere temperature of 850 ° C.). . After annealing, the steel sheet was cooled to 480 ° C without being exposed to the outside air, and was further exposed to the outside air.
In molten Zn bath with total Al concentration and total Fe concentration listed in 3 (bath temperature 460
(° C) for 1 second to perform hot dip Zn plating. A vertical hot-dip Zn plating apparatus was used for hot-dip Zn plating. After hot dip Zn plating, the amount of plating adhered by gas wiper is about 50g / m
² (per side) and then in a salt bath at 500 ° C.
The alloying treatment was performed by immersing during the alloying treatment times listed in -1 to Table 1-3.

From the alloyed test material to JIS K685
Tensile shear test pieces according to 0 were produced. An adhesive CYBOND manufactured by Konishi Co., Ltd. was applied to this test piece in a thickness of about 3 mm, and then a tensile shear test according to JIS K6850 was performed. After that, the peeled area at the interface is divided by the total area of the test piece, and the plating peeled area ratio (%) is calculated to obtain the alloyed molten Zn.
The adhesion of the plated steel sheet was evaluated. A large plating separation area ratio means low adhesion at the interface, and a small plating separation area ratio means high adhesion at the interface.
The results are shown in Tables 1-1 to 1-3 together with the composition of the plating layer.

Test Nos. 1 to 14 are examples of the present invention. The plating separation area ratio is 20% or less, and the adhesiveness at the interface is remarkably high as compared with the comparative example described later.

Test Nos. 15 to 16 are comparative examples. This is a case where Si which is positively added in the present invention is not contained at all. The plating separation area ratio was 40 to 45%.

Test No. 17 is a comparative example. This is a case where the content of Si positively added in the present invention is reduced to 0.05% or less and the relationship between P (%) and Ti (%) is reversed to Ti (%) <P (%). . The plating separation area ratio was 55%.

Test Nos. 18 to 19 are comparative examples. The present invention does not contain Si to be positively added at all, and Al is Zn 0.
This is the case when it is lowered to less than 20%. Plating peeling area ratio
It was 65%.

Test Nos. 20 to 21 are comparative examples. The content of Si positively added in the present invention is reduced to 0.05% or less,
Moreover, the relationship between P (%) and Ti (%) is Ti (%) <P (%)
This is also the case when the Al content is reversed and the Al content is as low as less than 0.20% of Zn. The plating separation area ratio was 65 to 70%.

Test No. 22 is a comparative example. P (%) and Ti
Reverse the relationship with (%) as Ti (%) <P (%), and
This is the case when Al is made as low as 0.20% of Zn. The plating separation area ratio was 70%.

Test Nos. 23 to 26 are comparative examples. P (%)
And Ti (%) is reversed to Ti (%) <P (%). The plating separation area ratio was 45 to 65%.

Test Nos. 27 to 32 are comparative examples. Al is Zn
This is the case when it is lowered to less than 0.20%.

The plating separation area ratio was 65 to 75%.

Test Nos. 33 to 35 are comparative examples. This is the case when the Ti content is reduced to 0.04% or less. The plating separation area ratio was 55 to 70%.

Test Nos. 36 to 38 are comparative examples. This is the case where the content of Si positively added in the present invention is increased to more than 0.25%. Since non-plating occurred in the hot-dip Zn plating process, the alloying treatment and thereafter were stopped.

As is clear from the comparison between the present invention example and the comparative example, if the composition of the base steel sheet and the composition of the plating layer are within the range of the alloyed hot dip Zn plated steel sheet of the present invention, It can be seen that an alloyed hot-dip Zn plated steel sheet with excellent adhesion can be obtained.

[0060]

[Table 1-1]

[0061]

[Table 1-2]

[0062]

[Table 1-3]

[0063]

The alloyed hot dip Zn plated steel sheet of the present invention has excellent adhesion. Therefore, the present invention can be applied to applications under severer conditions than before, such as applications involving impact deformation processing or shearing processing, applications requiring a high degree of deep drawability, or applications involving bonding with an adhesive.

[0064]

Claims (2)

[Claims] 1. The composition of the steel sheet used as the base material is, in wt%, C: 0.008% or less, Si: more than 0.05% to 0.
25% Mn: more than 0.08% to 0.7%, P: 0.075% or less, S: 0.02% or less, N: 0.005% or less, Al: more than 0.005% to 0.05%, and Ti: more than 0.04% to 0.2% or Ti: more than 0.04% to 0.2% and Nb: 0.02% or less, the balance consisting of Fe and unavoidable impurities, and Ti (%)> P (%) is satisfied. The composition of the plating layer to be formed on the alloy contains Fe: 8 to 15% by weight and the balance is Zn, Al and inevitable impurities.
In addition, alloyed molten Zn with excellent adhesion characterized by satisfying Al (%) = [(0.20 to 0.50) / 100] x Zn (%)
Plated steel sheet. 2. An alloyed hot-dip galvanized steel sheet excellent in adhesion according to claim 1, wherein the steel sheet as a base material further contains B in an amount of 20 ppm or less in addition to the composition of claim 1.