JPH0525600A - Manufacture of hot dip galvanized steel sheet by pre-ni alloy plating and alloying method - Google Patents

Abstract

PURPOSE:To provide a method for manufacturing a hog dip galvanized steel sheet and a galvannealed steel sheet by a pre-Ni alloy plating method for improving the galvanizing properties of a steel sheet for building materials, house appliances and automobiles and also the plating adhesion of galvannealing, to suppress the elution of pre-plating at the time of galvanizing. CONSTITUTION:This steel sheet is a hot dip galvanized steel sheet having features that the surface of a steel sheet is plated with an Ni alloy contg. >=0.1% of one or >=two kinds of P, S, B, Mo, Zn, Fe, Co, Cu, Cr, Sn and W by 0.2 to 2g/m<2>, and after that, it is heated to 420 to 500 deg.C sheet temp. in a nonoxidizing atmosphere, is immersed into a galvanizing both contg. 0.05 to 1% Al for <=15sec at >=350 deg.C or at >=30 deg.C/s temp. rising rate in a stage till the steel sheet is impregnated into the bath and is galvanized. Furthermore, right after wiping subsequent to the galvanizing, this steel sheet is subjected to alloying treatment in the temp. range of 470 to 550 deg.C for 5 to 40sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot dip galvanized steel sheet using a pre-Ni alloy plating method and a method for producing an alloyed hot dip galvanized steel sheet.

[0002]

2. Description of the Related Art Recently, when hot-dip galvanized steel sheets and alloyed hot-dip galvanized steel sheets are used for building materials, home appliances or automobiles, they have an excellent surface appearance regardless of the sheet thickness or hot rolling or cold rolling. In addition, it has become an important performance to be equipped with excellent plating adhesion and plating adhesion of severely processed parts such as powdering resistance. Japanese Patent Publication No. 46-19282 or Japanese Patent Publication No. 63-489
The hot-dip Zn-plated steel sheet by the pre-Ni plating method disclosed in Japanese Patent No. 23, when compared with the conventional Zenzimer method without pre-Ni plating and the hot-dip galvanizing method of the non-oxidizing furnace method,
Appearance or plating adhesion is good, but Ni
Since heating conditions such as heating temperature and heating time after plating are insufficient, it is especially required for building materials currently required for hot-rolled pickling of thick plates, surface appearance for home appliances, plating adhesion, and more. It is insufficient to secure the plating adhesion (powdering resistance) and the corrosion resistance of the processed part, which is severe for automobile applications.

[0003]

On the other hand, the pre-Ni proposed by the present inventors in Japanese Patent Application No. 3-102825 and the like is proposed.
The method for producing hot-dip galvanized steel sheet and alloyed hot-dip galvanized steel sheet using plating and rapid low-temperature heating is the same as the above-mentioned conventional Zenzimer method, non-oxidizing furnace hot-dip galvanizing method and pre-plating method for cold-rolled steel sheet and hot-rolled steel sheet. It is an excellent method that can secure extremely good plating properties and plating adhesion of the processed part as compared with the hot dip Zn plating method by the Ni plating method. However, at the time of hot dip Zn plating, part of the pre-Ni plating layer is in the Zn plating bath. Since it easily elutes into Ni, it tends to cause dross etc. during long-term operation.
There was an improvement point that the residual rate of plating was improved. Therefore, the inventors of the present invention have made various studies, and by eutectifying a specific element having a high affinity for Ni with Ni during pre-Ni plating, elution of Ni during hot-dip Zn plating is suppressed, and good hot-dip Zn is obtained. It was found that the plating property was obtained, and even when the hot-dip Zn-coated steel sheet was alloyed, a good alloy plating layer was obtained, and the plating adhesion of the processed part was also excellent. The present invention is a pre-Ni alloy plating consisting of a specific element as described above, a hot-dip Zn-plated steel sheet excellent in Zn-plating property by performing heating under specific conditions, and an alloyed hot-dip Zn plating excellent in plating adhesion of a processed portion. A method for manufacturing a steel sheet is provided.

[0004]

[Means for Solving the Problems] First, the inventors of the present invention first eutectate Ni and various elements during pre-Ni plating, and after heating under specific heating conditions, perform hot-dip Zn plating to obtain plating property and plating. The amount of Ni remaining in the layer was measured. Furthermore 4
An alloying treatment was also performed in the range of 70 to 550 ° C. to produce a galvannealed steel sheet, and the plating adhesion of the processed part was examined. As a result, P, S, B, Mo, Z on the surface of the steel plate
0.2 to ² g / m ^{2 of} Ni alloy containing 0.1% or more of one or more of n, Fe, Co, Cu, Cr, Sn and W
After plating, after heating under specific heating conditions, zinc plating after heating, and further by alloying treatment, the pre-plating residual amount at the time of plating increases, and the hot-dip galvanizability and the alloyed hot-dip galvanized steel sheet It has been found that the plating adhesion becomes good. Furthermore, it is an essential condition that the bath penetration plate temperature after the Ni alloy plating treatment is low, and the speed at which the bath penetration plate temperature reaches the bath penetration plate temperature is fast. Like the normal method,
If it is heated at a high temperature and kept at a high temperature for a long time, the pre-Ni alloy plating layer diffuses into the base metal and the molten Zn
The plating property and the plating adhesion of the processed part after the alloying treatment were not improved. After pre-Ni alloy plating, the steel plate is Al
The heating temperature range until entering the Zn bath containing 0.1 to 1% is 420 ° C. or more and 500 ° C. or less, and after reaching the temperature of 350 ° C. or more, which is the temperature at which the Ni alloy plating easily diffuses into the base iron. It was found that both the appearance of the hot-dip Zn coating and the plating adhesion were significantly improved when the time required to reach the temperature just before entering the bath was within 15 seconds. In addition, the heating rate after pre-Ni plating can be further rapidly increased to 30 ° C./s or more to perform hot-dip Zn plating, whereby the plating adhesion and the corrosion resistance of the processed part can be dramatically improved when subjected to severe processing. I found it.
Further, it is possible to obtain an alloyed hot-dip Zn-plated steel sheet excellent in surface appearance and plating adhesion of the processed portion only when alloying treatment is performed under appropriate alloying conditions after hot-dip Zn plating by the above method. Was also found.

The present invention described below has been completed based on the above circumstances. That is, P, S, B, M on the surface of the steel plate
1 of o, Zn, Fe, Co, Cu, Cr, Sn, W
Or Ni containing 0.1% or more of a composite of two or more kinds
After the alloy is plated with 0.2 to 2.0 g / m ^{2, the} alloy is heated to a temperature of 420 ° C. or higher and 500 ° C. or lower in a non-oxidizing atmosphere,
In the process until the steel sheet enters the bath, the time at which the temperature is 350 ° C. or higher is within 15 seconds, and the steel sheet is dipped in a molten Zn bath containing 0.05 to 1% of Al without being exposed to the atmosphere for galvanization. Method for producing hot dip galvanized steel sheet and P, S, B, Mo, Zn, F on the surface of the steel sheet
One or two of e, Co, Cu, Cr, Sn, W
0.2% of Ni alloy containing 0.1% or more of compounded species
~ 2g / m ² After plating, 430-50 in non-oxidizing atmosphere
Melting characterized by rapid heating up to 0 ° C. at a temperature rising rate of 30 ° C./s or more, and then dipping in a molten Zn bath containing Al 0.05 to 1% without contact with the atmosphere for galvanization A method for producing a galvanized steel sheet and the hot-dip galvanized steel sheet according to claims 1 and 2 above, and further subjected to an alloying treatment at 470 to 550 ° C. for 10 to 40 seconds immediately above the wiping. Manufacturing method. The non-oxidizing atmosphere in the present invention means a non-oxidizing atmosphere (for example, H ₂ 0.1 to 3% + N ₂ , O ₂ number 10).
ppm) or a reducing atmosphere (eg H ₂ 15%
+ N ₂ atmosphere).

The present invention will be described in detail below with reference to the drawings. FIG. 1 shows P, Mo, or Z in the pre-Ni alloy plating layer that affects the Ni residual ratio during hot-dip Zn plating.
It is a figure showing the influence of the content rate of n. A hot-rolled Al-killed steel sheet (1.6 mm) was electroplated with a 0.5 g / m ² pre-Ni alloy plating layer and heated at 40 ° C./s in an N ₂ atmosphere containing 60 ppm O ₂ and 3% H ₂ by electric heating. It was heated to 450 ° C. and immediately plated for 3 seconds in a molten Zn plating bath containing 0.2% Al. The Ni residual ratio was obtained by quantifying the amount of Ni in the hot-dip Zn plating layer by chemical analysis, and determining the ratio to the amount of adhesion before hot-dip Zn plating. When each alloy element is 0.1% or more in the Ni plating layer, the Ni residual rate is improved, and as the content rate increases, Ni easily remains. Therefore, the amount of dross generated when plating was performed for a long time was extremely small as compared with the case where Ni was used alone. The same was true for other pre-Ni alloy-based plating.

FIG. 2 is a diagram showing the relationship between the hot plate temperature after Ni-P plating and the hot dip Zn plating property. 0.5g / m ² pre-Ni on hot rolled Al killed steel plate (plate thickness 1.6mm)
-P (12%) plating layer is electroplated and O ₂ 60pp
m, H ₂ by 20% by electric heating in an N ₂ atmosphere containing 3%
It was heated to 0 to 550 ° C. and immediately plated in a molten Zn plating bath containing 0.2% Al for 3 seconds. The time from when the heating plate temperature reached 350 ° C. or higher to when the heating plate temperature reached the bath penetration plate temperature was 10 sec. The coating weight is 135 g / m ² . The plating property was evaluated by comprehensively evaluating the plating appearance (the degree of non-plating) and the plating adhesion (ball impact test B.I.). The evaluation criteria are as follows.

[0008] From this figure, when the heating plate temperature before hot dip coating is in the range of 420 to 500 ° C. which is the range of the present invention, the plating appearance and the plating adhesion are extremely excellent. Plating appearance below 420 ° C
Plating adhesion tends to deteriorate. Also, the heating plate temperature is 500
If the temperature exceeds ℃, the adhesion and corrosion resistance will deteriorate. Other pre Ni
The same was true for alloy-based plating.

FIG. 3 shows the relationship between the heating temperature and the amount of diffusion of the pre-Ni-P alloy plating layer into the base metal. 0.2 g / m ² pre-Ni on hot rolled Al killed steel plate (plate thickness 1.6 mm)
The -P alloy plating layer was electroplated, O ₂ 60ppm, H ₂
After heating for 5 seconds by electric heating in an N ₂ atmosphere containing 3%, the residual rate of the Ni plating layer was increased by Auger (A
It was determined by depth direction analysis by ES). Heating temperature about 3
It is obvious that any pre-Ni alloy plating layer starts to diffuse into the base iron at 50 ° C. or higher, and when it exceeds 500 ° C., almost no Ni layer remains. Next, Ni-P (12%)
After plating, in the process of reaching the bath penetration temperature,
FIG. 4 shows the relationship between the time until the bath penetration temperature is reached after the temperature at which Ni starts to diffuse at 350 ° C. and the hot-dip galvanizing property. Hot rolled Al killed steel plate (plate thickness 1.6
mm) is electroplated with a 0.5 g / m ² pre-Ni-P plating layer and heated by electric heating in a N ₂ atmosphere containing 60 ppm of O ₂ and 3% of H ₂ to reach a bath penetration plate temperature of 450 ° C. Immediately, it was immersed in a Zn plating bath containing 0.2% Al at 450 ° C. for 3 sec plating. The basis weight is 135
It was set to g / m ² . It is apparent that the hot-dip galvanizability is good when the time from reaching 350 ° C., which is the range of the present invention, to reaching the bath penetration temperature is within 15 seconds. The same was true for the other pre-Ni alloy plating systems. Furthermore, when the average heating rate (heating rate) from the start of heating after Ni-P plating to the bath penetration plate temperature is 30 ° C./s or more, the plate temperature of 350 ° C. in FIG.
It takes 5 seconds or less to reach the bath penetration plate temperature, but it is also clear that the hot-dip Zn plating property is extremely good.

FIG. 5 is a diagram showing the relationship between the heating rate of heating after pre-Ni-P plating and the plating adhesion of the processed portion of the alloyed hot-dip Zn plating layer. A hot-rolled Al-killed steel plate (plate thickness: 1.6 mm) is electroplated with a 0.5 g / m ² pre-Ni-P plating layer, and electrically heated to 450 ° C. in an N ₂ atmosphere containing 60 ppm of O ₂ and 3% of H ₂ After heating by changing the temperature rise rate by, the plating is performed for 3 seconds in a molten Zn plating bath of Al 0.15%, and the temperature is 500 ° C just above the wiping.
The alloying treatment was performed for 15 seconds. Plating weight is 60g /
It was set to m ² . As a powdering resistance test for plating adhesion in order to reproduce a severely processed part, a test piece was subjected to cup drawing with a 25 mm overhang, and then a tape peeling test was carried out to evaluate the degree of blackening of the tape. Evaluation was made by a 5-point method. The point of 3 or more is the case where the plating adhesion becomes good when subjected to severe processing. The evaluation criteria are as follows. It is clear that when the temperature rising rate after Ni-P plating is set to 30 ° C / s, the plating adhesion of the processed portion becomes good when severe processing is performed. Further, from the viewpoint of plating adhesion of such a severely processed part, the heating plate temperature is 430.
The best temperature was above 500 ° C. These results were the same for other pre-Ni alloy-based platings. Further, during this alloying treatment, in the Ni-Fe based pre-Ni alloy plating, the Fe% in the alloyed hot-dip Zn plating layer is likely to increase due to the diffusion of Fe in the pre-Ni-Fe plating layer, which is It was also confirmed to be advantageous.

As described above, in the present invention, the alloying additive element in the pre-Ni plating layer is a specific element,
The heating temperature after alloy plating is within a specific range, 35
The time from reaching 0 ° C until reaching the bath penetration plate temperature is within 15 sec.
This is a major point in the production of an n-plated steel sheet and an alloyed hot-dip Zn-coated steel sheet having excellent plating adhesion of the processed part. Furthermore, the heating rate after pre-Ni plating is 30 ° C /
Setting it to s or more is a further point in the production of the hot-dip galvanized steel sheet and the alloyed hot-dip galvanized steel sheet which have excellent plating adhesion in severely worked parts. The heating method is not particularly limited, but various methods such as a method for directly electrically heating the steel sheet, an induction heating method, an infrared heating method, and the like can be applied. The direct heating method is effective in that it is easy to quickly set the heating rate from a thin plate to a thick plate of more than 3 mm, and compact equipment is possible. In the case of a hot rolled material, it is important to pickle the black leather material under appropriate conditions in order to improve the plating property of the pre-Ni alloy plating. For example, it is desirable to perform pickling in 90% 8% HCl for about 20 to 150 seconds. Further, in some cases, it is more desirable to carry out a polishing treatment of a brush scrubber, sandpaper, etc., electrolytic polishing, electrolytic pickling after the pickling. Pre N
The upper limit of the alloy element content in the i-alloy plating is not particularly specified, but the effect on the elution of Ni during hot-dip Zn plating is saturated, and the current efficiency during pre-plating deteriorates, impairing economic efficiency. Considering this, about 50% or less is desirable.

Pre-Ni alloy plating coverage is 0.2 g / m
^The reason for setting ² or more is that the non-plating of the hot dip Zn plating is eliminated and the Fe-Al-Zn-Ni-based 4
This is because an original alloy layer is formed, the above-described development of the Fe—Zn alloy layer is suppressed, and plating adhesion is improved. When the Ni alloy plating adhesion amount is less than 0.2 g / m ² , non-plating is likely to occur and plating adhesion is likely to deteriorate. The upper limit is set to 2.0 g / m ² because the plating adhesion deteriorates when the amount exceeds 2.0 g / m ² . In this case, the base steel interface Ni-Al-
The Zn-based alloy layer increases, and it becomes difficult to form a Fe-Al-Zn-Ni-based quaternary alloy layer that is a barrier layer for alloying Zn and base iron, and the alloying of Zn and base iron progresses. It is thought to be because. Further, the plating adhesion was insufficient even when the Al content in the bath was less than 0.05%. In this case, Fe
Almost no Al-Zn-Ni-based alloy layer was formed, and the Zn-Fe alloy layer was thickly grown at the base iron interface.
In particular, the brittle Γ phase (Fe ₅ Zn ₂₁ ) at the interface is developed,
It was found that cracks appeared during processing and plating peeling occurred from this phase. Further, the Al content in the bath is set to 1% or less because if it exceeds this, the surface appearance becomes whitish, and if Al becomes unevenly unevenly distributed in the plating layer, these are This is because the risk of causing deterioration of corrosion resistance due to the action of leaching Zn out of the local battery is considered.

The optimum alloying treatment temperature is 470 to 550 ° C. If it is less than 470 ° C, alloying is difficult to proceed, and it is 550
If the temperature exceeds ℃, alloying will proceed too much, and the Γ phase will easily develop at the base iron interface, and the plating adhesion of the processed part will deteriorate. The alloying time depends on the balance with the alloying temperature, but it is 5
A range of -40 seconds is suitable. If it is less than 5 seconds, the alloying is difficult to proceed, and if it exceeds 40 seconds, the alloying is too advanced and the Γ phase is easily developed, and the plating adhesion of the processed part is deteriorated. The coating amount is not particularly limited, but is preferably 10 g / m ² or more from the viewpoint of corrosion resistance and 350 g / m ² or less from the viewpoint of workability. The above results have been described only in the case of the Zn plating bath.
In addition to Al in the n plating bath, Ni as an alloying element,
The results were the same in the case of a hot-dip galvanized steel sheet containing a trace amount of Sb and Pb alone or in a combined amount of 0.2% or less. Regarding the bath temperature, even in the case of the Zn bath, Zn
430-50 even if the bath contains a trace amount of alloying elements
Normal conditions of about 0 ° C. can be used. As the base steel sheet, both hot-rolled steel sheet and cold-rolled steel sheet can be used. Al-killed steel sheet, Al-Si-killed steel sheet, Ti-Sulc, P-Ti
Various materials such as Sulc low carbon steel sheet and high tensile steel sheet can be applied.

[0014]

In the present invention, P, S, B, Mo, Zn, F
The reason why the elution amount of Ni into the molten Zn bath at the time of hot dip Zn plating by the Ni alloy plating with e, Co, Cu, Cr, Sn, and W is smaller than that in the case of Ni single plating is not yet clear. However, it is considered that one reason is that Ni has a strong affinity with these elements and is hard to be separated. In addition, especially Ni-P, Ni-S, Ni-B, Ni-
It is known that Mo, Ni-Co-B, etc. have an amorphous structure in the plating layer in a part of the composition range of the present invention. Therefore, corrosion resistance is good, and Ni is difficult to elute in the molten Zn bath. It is also possible that it has become. Further, the structure of the plating layer obtained by the method of the present invention and the structure of the plating layer obtained by the conventional pre-Ni method were analyzed, and the heating conditions after the pre-Ni alloy plating within the scope of the present invention, that is, the heating plate temperature was 4
At 20 to 500 ° C, the diffusion of the pre-Ni alloy plating layer into the base metal is small and the residual amount is large within a period of 15 s from reaching 350 ° C to the bath penetration plate temperature, and further, When the temperature rising rate after pre-Ni alloy plating was 30 ° C / s or more, it was found that the Ni alloy plated layer remained almost in the plated state and almost no diffusion into the base iron was observed. did. On the other hand, when the heating temperature in the prior art range is high (more than 500 ° C.), when the time from reaching 350 ° C. to reaching the bath penetration plate temperature is too long, the Ni alloy is mostly in the base steel. To a solid solution layer with Fe. Further, when the heating temperature is lower than 420 ° C., Ni remains, but non-plating is likely to occur during hot dipping, resulting in poor adhesion. Since the state of Ni alloy plating at the time of heating is different, it is considered that the difference in the plating layer constitution occurs at the time of subsequent hot dipping. That is, the Ni deposition amount of the present invention is 0.2 to
At 2.0 g / m ² , the pre-Ni layer left largely at the base iron interface was Fe-Al-Zn-Ni-α (α = P, S, B, Mo) near the base iron interface during the hot dip Zn plating. ，
A Zn, Fe, Co, Cu, Cr, Sn, W) -based alloy layer (barrier layer) was formed, and the Zn-Fe alloy layer was thin and growth was suppressed. Moreover, the Zn plating layer containing Al was formed in the upper layer. On the other hand, in the conventional method, since the pre-Ni alloy layer hardly remains at the time of heating, the Fe-Al-Zn-Ni- [alpha] -based alloy layer at the base iron interface as in the present invention during the hot dip Zn plating. Is not formed, and a thick Zn—Fe layer is formed on the upper layer of the Fe solid solution layer formed during heating.
The structure was such that a Zn layer containing was formed. Although details are not clear, in the present invention, the appearance of hot-dip Zn coating, the adhesion of plating, and the adhesion of the processed part of the alloyed hot-dip Zn-plated steel sheet were dramatically improved because
-Al-Zn-Ni- [alpha] -based alloy layer plays a role of a kind of binder, and Zn-Fe which is brittle at the base iron interface
This is probably because it has a barrier effect of suppressing the growth of the alloy layer (Γ phase).

[0015]

EXAMPLES Table 1 shows examples of the production method of the present invention and the obtained samples. * Indicates a comparative material prepared by a manufacturing method other than the present invention. As a base, Al killed hot rolled pickled steel sheet (1.
6 mm) was used. After applying each pre-Ni alloy plating in the sulfuric acid acid bath by electroplating while changing the adhesion amount,
After pretreatment heating was performed in an atmosphere of O ₂ 60 ppm, H ₂ 3% + N ₂ by changing the heating conditions, the bath temperature was 450 ° C., and 3
Hot dipping was performed in sec. Furthermore, after wiping a part, alloying heat treatment is carried out at 450 to 550 ° C. for 5 to 5 ° C.
It went for 40 seconds. The coating weight was 60 g / m ² . Evaluation of the residual ratio of the pre-Ni alloy plating layer after hot dip galvanizing, hot dip galvanizing properties such as plating appearance and plating adhesiveness, and the plating adhesiveness of the processed part of the alloyed hot dip galvanized steel sheet are based on the aforementioned test method and evaluation criteria. Was evaluated according to. Further, the degree of alloying after the alloying treatment was evaluated in three ranks of A (best), B (good), and C (bad), and B or more was regarded as acceptable. No. 1
~ 69, the steel sheet obtained by the production method of the present invention, the residual rate of pre-Ni alloy plating layer after hot-dip Zn plating, hot-dip galvanizing, adhesion of the working portion of the alloyed hot-dip galvanized steel sheet Excel. In comparison, when the type of the pre-Ni alloy plating layer, the adhesion amount, the heating conditions, the Al in the bath, and the alloying treatment conditions deviate from the scope of the present invention (No. 70 to 8).
1), the residual rate of the pre-plated layer during hot-dip Zn plating, hot-dip Zn plating property, and plating adhesion of the processed part of the alloyed hot-dip Zn plated steel sheet are poor. Furthermore, No. Nos. 82 to 85 are cases where a small amount of other alloying elements were contained in the hot-dip Zn plating bath, and excellent performance was exhibited also in this case.

[0016]

[Table 1A]

[0017]

[Table 1B]

[0018]

[Table 1C]

[0019]

[Table 1D]

[0020]

As described above, according to the present invention, since the pre-plating layer is less eluted into the molten Zn plating bath during production, dross is less likely to occur, which is advantageous in the conventional plating. Of galvanized steel sheet and alloyed hot-dip galvanized steel sheet having excellent properties or plating adhesion of the processed part and being useful as a structural material for building materials, home appliances or automobiles, their industrial significance is extremely large.

[Brief description of drawings]

1] Pre-N effect on Ni residual ratio during hot dip Zn plating
The figure which showed the influence of the content rate of the alloying element in i alloy plating layer,

FIG. 2 is a diagram showing a relationship between a hot plate temperature after Ni—P plating and hot-dip Zn plating property,

FIG. 3 is a diagram showing a relationship between a heating temperature and a diffusion amount of a pre-Ni alloy plating layer into a base iron,

FIG. 4 is a diagram showing the relationship between the time from the temperature of 350 ° C. to the bath penetration temperature after pre-Ni-P plating and the hot-dip galvanizability,

FIG. 5 is a diagram showing a relationship between a heating rate of heating after pre-Ni-P plating and plating adhesion of a processed portion of an alloyed hot dip Zn plating layer.

Claims (3)

[Claims] 1. A steel sheet having P, S, B, Mo, Zn,
A Ni alloy containing 0.1% or more of one or more of Fe, Co, Cu, Cr, Sn, and W in a composite is added.
420 to 5 in non-oxidizing atmosphere after ^{2 to 2} g / m ² plating
In the process of heating to a temperature of 00 ° C and entering the bath into the bath, the steel plate is immersed in a molten Zn bath containing 0.05 to 1% of Al without touching the atmosphere for 15 seconds or more at 350 ° C or less. 1. A method for manufacturing a hot-dip galvanized steel sheet, which comprises performing galvanizing with a steel sheet. 2. A surface of a steel sheet containing P, S, B, Mo, Zn,
A Ni alloy containing 0.1% or more of one or more of Fe, Co, Cu, Cr, Sn, and W in a composite is added.
After plating ^{2 to 2} g / m ² , it is 430 to 5 in non-oxidizing atmosphere.
Hot-dipped zinc characterized by being rapidly heated to 00 ° C. at a heating rate of 30 ° C./s or more, and then dipped in a molten Zn bath containing 0.05 to 1% of Al without being exposed to the atmosphere for galvanization. Manufacturing method of plated steel sheet. 3. The alloyed molten Zn according to claim 1, further comprising an alloying treatment immediately after wiping at 470 to 550 ° C. for 5 to 40 seconds after the hot dip Zn plating.
Manufacturing method of plated steel sheet.