JP2704045B2 - Surface-treated steel sheet with few plating defects and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a galvanized steel sheet or a zinc-based alloy-plated steel sheet used for automobiles, home appliances, and building materials.
In particular, the present invention relates to a galvanized steel sheet or a zinc-based alloy-plated steel sheet using a high-tensile steel sheet as a material and a method for producing the same.

BACKGROUND ART In recent years, surface-treated steel sheets having high corrosion resistance have been demanded in fields such as automobiles and home appliances, and various zinc-based plated steel sheets have been developed and put into practical use. Among these, hot-dip galvanized steel sheets such as hot-dip galvanized steel sheets (hereinafter abbreviated as GI) and alloyed hot-dip galvanized steel sheets (hereinafter abbreviated as GA) are less expensive and have better manufacturing costs than electro-galvanized steel sheets. Due to its corrosion resistance, it is currently being put to practical use not only as an inner plate but also as an outer plate as a rustproof steel plate for automobiles. Further, in the field of electroplating, a steel sheet having high corrosion resistance even with a relatively small thickness can be provided by alloy plating in which an alloy such as Zn-Ni or Zn-Fe other than pure zinc is electrodeposited.

Recently, reduction of automobile exhaust gas has been taken up as an important issue due to global environmental problems, and it has become mandatory for automobile manufacturers to reduce vehicle weight. Against this background, gauge down of steel sheets is effective in reducing the weight of automobile bodies.Therefore, material manufacturers are strongly required to supply high-tensile steel sheets. Research and development of high-strength steel sheets with the addition of Si, Mn, P, Ti, Nb, Al, Ni, Cu, Mo, V, Cr, B, etc. as elements that increase the strength of steel sheets without impairing the formability of steel ing. In addition, since steel sheets have been required to be provided with rust-preventive properties, the development of high-strength steel sheets with zinc-based plating, especially hot-dip zinc-plated, which is inexpensive to manufacture, is strongly desired by automobile manufacturers. ing.

However, since the strengthening elements in the above steel are easily oxidized and are not easily reduced, the Sendzimir type production line, which is currently a typical continuous production line for hot-dip plating, selectively oxidizes these strengthening elements during annealing to increase the surface concentration. The essential problem arises. In this case, the wettability between the steel sheet and the molten zinc is significantly reduced by the oxides of reinforcing elements such as Si and Mn concentrated on the steel sheet surface during annealing, so that the adhesion of the hot-dip coating is significantly reduced. Causes a phenomenon such as so-called non-plating in which molten zinc does not adhere to the steel sheet at all. In addition, in the case of GA manufactured by performing an alloying process subsequent to hot-dip plating, alloying is significantly delayed due to oxides of strengthening elements generated at the time of annealing, and it is not possible to perform the alloying process unless the alloying temperature is extremely increased. Problems also arise.

Also, in the case of electro-zinc plating, since the elements in the steel are concentrated on the surface during the annealing treatment which is a pre-step of plating to form a strong film, unless the oxide film is mechanically or chemically removed after annealing, Zinc plating cannot be electrodeposited on steel sheets.

When hot-dip galvanizing or electro-zinc plating is applied to such difficult-to-plate materials, in order to prevent non-plating,
Methods have been developed to solve the above problem by pre-treating the steel sheet surface in advance.

For example, JP-A-57-70268, JP-A-57-79160, and JP-A-58-104163 disclose methods of applying Fe plating to a steel sheet before hot-dip galvanizing.

DISCLOSURE OF THE INVENTION However, the method using the above-mentioned electro-Fe plating includes:
At least 10g / Fe coating weight required to prevent non-plating
Since m ² or more is required, there is a problem that a large-scale facility is required and the manufacturing cost is increased. Also, depending on the type and amount of elements in steel and annealing conditions,
Even if Fe plating is applied, it may be difficult to completely suppress the occurrence of non-plating.

The object of the present invention is to strongly oxidize Si, Mn, P, Ti, Nb, Al, N
Elements such as i, Cu, Mo, V, Cr, B, among which Si, Mn,
Low cost and stable suppression of non-plating when steel sheet containing elements such as P is subjected to hot-dip galvanizing and alloyed hot-dip galvanizing after annealing in a continuous line, and also to electroplating after annealing The present invention provides a method and a surface-treated steel sheet with less non-plating.

The present invention, when zinc-based plating on a high-tensile steel sheet containing a strongly oxidizable element, by applying Fe plating containing oxygen before annealing, the element in the steel at the interface between this Fe plating layer and the steel sheet during annealing High-strength steel sheet zinc-plated steel sheet with good plating properties by forming a concentrated layer of steel and suppressing the diffusion of elements in steel to the surface of the Fe plating during annealing by the barrier of the concentrated layer And a method for producing the same.

That is, the present invention provides a steel sheet in which a zinc plating layer or a zinc-based alloy plating layer is applied to at least one surface of a steel sheet, the steel sheet having a Fe plating layer immediately below the zinc plating layer or the zinc-based alloy plating layer, It is another object of the present invention to provide a surface-treated steel sheet having a small number of plating defects, characterized in that the steel sheet has a concentrated layer of a component in steel immediately below the Fe plating layer.

Further, the present invention is at least one surface of the steel sheet, coating weight 0.1 to 10 g / m ² a and the oxygen content in the coating layer is 0.1 to 10
An object of the present invention is to provide a method for producing a surface-treated steel sheet having a small number of plating defects, wherein an annealing treatment is performed after Fe plating of wt% is performed, and then zinc or a zinc-based alloy plating is performed.

Here, the steel sheet to be subjected to Fe plating is Si, Mn, P, Ti, Nb, Al, N
i, Cu, Mo, V, Cr and at least one selected from the group consisting of B, Si, Ti, Ni, Cu, Mo, Cr and V is 0.1 wt% or more,
Mn is 0.5wt% or more, P, Al and Nb are 0.05wt% or more, B is
When the content is 0.001 wt% or more, the present invention is contained. In particular, the steel sheet to be plated with Fe is at least one selected from the group consisting of Si, Mn and P, and Si is 0.1 to 2.0 wt%.
The present invention is more effective when Mn is contained at 0.5 to 4.0 wt% and P is contained at 0.05 to 0.2 wt%. Therefore, the concentrated layer immediately below the Fe plating layer is also composed of one or more of these elements. To form an oxygen-containing Fe plating layer, 0.1 g / l or more,
Preferably 0.1-20 g / l, more preferably 0.1-10 g / l
It is preferred to use a bath containing Fe ³⁺ and containing a carboxylic acid or an alkali metal salt of a carboxylic acid.

In addition, the present invention relates to the method of
0.1 to 10 g / m ² and the oxygen content of the plating layer is 0.1 to 10 wt%
The present invention also provides an original plate for surface treatment which has been subjected to Fe plating.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a depth direction analysis result by GDS.
(A) is a diagram of an oxygen-containing Fe-plated material according to the present invention, and (b) is a diagram of a Fe-plated non-treated material.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

The steel sheet described in the present invention is a strengthening element capable of increasing the strength of a steel sheet without impairing formability in low-carbon steel or ultra-low-carbon steel used in automobiles, Si, Mn, P, Ti, Nb, Al, Ni, Cu, M
The steel sheet contains at least one or more alloying elements such as o, V, Cr, and B. In addition, to contain in the present invention,
Si, Ti, Ni, Cu, Mo, Cr, V contain 0.1 wt% or more, Mn contains 0.5 wt% or more, P, Al, Nb contains 0.05 wt% or more, and B contains 0.001 wt% or more.

In particular, in order to satisfy the strength required for a steel sheet to reduce the weight of an automobile body, and to secure sufficient formability and deep drawability, 0.1 wt% ≦ Si ≦ 2.0 wt% 0.5 wt% ≦ Mn ≦ 4.0 wt% 0.05 wt% ≦ P ≦ 0.2 wt% It is necessary to contain at least one or more of Si, Mn, and P in the concentration range.

The lower limit of the concentration range of each component element is determined because if the component concentration is lower than this value, the strength and deep drawability required for the steel sheet cannot be secured.

The reasons for setting the upper limit are as follows. That is, in the case of Si, if it exceeds 2%, the hot-rolled base sheet hardens remarkably and the cold-rolling property deteriorates. In the case of Mn, if it exceeds 4%, not only the increase in the strength of the steel sheet is saturated but also the r-value. This is to cause the deterioration of. The upper limit of the P concentration is determined because if P exceeds 0.2%, segregation during solidification becomes extremely strong, and not only the increase in strength is saturated, but also the workability is deteriorated.

In the present invention, whether the above-mentioned elements in the steel are used alone or in combination of two or more kinds, it is possible to select according to the strength required for the steel sheet and the deep drawability (r value). it can.

In addition, the present invention, when at least one or more of Si, Mn, P is contained in a steel sheet in the above composition range, in addition to the above elements, Ti, Nb, Al, Ni, Cu, Mo, V, Cr And B is also applied when containing at least one or more elements selected from the group consisting of elements. Here, containing means Ti, Ni, Cu,
Mo, Cr, V: 0.1 wt% or more, Al, Nb: 0.05 wt% or more, B: 0.0
01% by weight or more.

When galvanizing a steel sheet containing the above elements,
Non-plating occurs due to oxides of the respective elements concentrated on the surface during annealing of the steel sheet. In the present invention, as a result of various studies on a plating pretreatment method for suppressing the surface concentration of each of these highly oxidizable elements, by applying Fe plating containing a certain concentration of oxygen to the steel sheet, It has been found that it is possible to substantially completely suppress the surface enrichment of elements, and to ensure good plating properties during subsequent hot-dip zinc or hot-dip zinc-based alloy plating, electric zinc or electric zinc-based alloy plating. Was.

The reason why the oxygen-containing Fe plating suppresses the surface concentration of the elements in the steel during annealing is that the elements in the steel form a concentrated layer at the interface between the Fe plating and the base steel sheet due to the oxygen in the Fe plating layer during annealing. This is because the interface-concentrated layer suppresses the diffusion of elements in steel to the surface of the Fe plating. FIG. 1 shows an example.
As steel sheets, C: 0.002 wt%, Si: 1.0 wt%, Mn: 3.0 wt%, P:
A steel sheet containing 0.15 wt% and Al: 0.03 wt% was used. FIG.
In (a), without applying Fe plating, and FIG. 1 (b)
In each of the samples, an oxygen-containing Fe plating was applied at 4 g / m ² and annealed at a holding temperature of 850 ° C. for a holding time of 30 seconds. FIGS. 1 (a) and 1 (b) show the results of depth analysis by GDS for these samples, respectively. In FIG. 1A without Fe plating, it can be clearly seen that Si and the like are diffused to the surface of the steel sheet. In FIG. 1 (b) where oxygen-containing Fe plating has been applied, Si forms an interface-enriched layer at the interface between the Fe plating layer and the steel sheet, and the diffusion of Si to the surface is suppressed. You can see well. Since this interface-enriched layer is generated only when oxygen is present near the interface, the effect of suppressing the diffusion of elements in the layer by the interface-enriched layer as described above can be obtained by simple Fe plating, which is a conventional technique. Absent. In the case of Fe plating that does not contain oxygen in the range disclosed in the present invention, a barrier when elements in steel diffuse to the Fe plating surface during annealing is not generated at the interface. In order to suppress the diffusion of elements, it is necessary to greatly increase the amount of deposition of Fe plating, which is not only disadvantageous in terms of operation and equipment, but also cannot suppress surface concentration depending on annealing conditions. There are cases.

The amount of Fe-containing plating containing oxygen in the present invention is:
It should fall in the range of 0.1 to 10 g / m ^2. The above reason is because Fe
When the coating weight is less than 0.1 g / m ² , the effect of suppressing non-plating is insufficient, and when the coating weight exceeds 10 g / m ² , the effect of improving the plating property is not only saturated but also disadvantageous in cost. is there.

The range of the oxygen concentration that the Fe plating layer contains before annealing is
Must be 0.1 to 10 wt%, preferably 1 to 10 wt%
It is. If the oxygen concentration is less than 0.1 wt%, the above-mentioned interface-enriched layer having the effect of suppressing the diffusion of the elements in the steel to the surface is not sufficiently generated, and the surface elements of the steel are concentrated during annealing. High plating properties cannot be obtained. Also, the oxygen concentration
If it exceeds 10 wt%, the oxygen contained in the Fe plating layer itself cannot be sufficiently reduced at the time of annealing, and the plating property and plating adhesion will be deteriorated due to the oxygen that cannot be completely reduced.
Therefore, when a steel sheet containing an element in steel that is easily oxidized is annealed and plated with zinc or a zinc-based alloy, a sufficient plating property improving effect by Fe plating is only achieved by controlling the oxygen content in the Fe plating layer to the above range. Can be obtained.

Oxygen in the Fe plating layer ^reduces the Fe ³⁺ concentration in the electroplating bath.
The concentration can be controlled within the above range by adjusting the concentration to 0.1 g / l or more, preferably 0.1 to 10 g / l, and adding a carboxylic acid to the bath. If the Fe ³⁺ concentration is less than 0.1 g / l, the oxygen concentration in the plating layer cannot be sufficiently increased, and the plating property cannot be effectively improved. The upper limit of the Fe ³⁺ concentration is not particularly specified, but if it exceeds 20 g / l, the plating adhesion of the Fe plating itself deteriorates when the coating weight is small, and the oxygen concentration in the Fe plating becomes too high. As described above, the oxygen in the plating during the annealing is not sufficiently reduced and remains, and the plating property tends to be deteriorated.Therefore, 20 g / l or less is preferable, and if a more stable effect is expected, 10 g / l It is preferably within the range of l or less.

In order to include oxygen in the Fe plating layer, a carboxylic acid is essential in addition to Fe ³⁺ . The carboxylic acid referred to here is formic acid, acetic acid or the like, benzoic acid, oxalic acid, acrylic acid, or the like.In the present invention, a metal salt such as an alkali metal salt of a carboxylic acid other than the carboxylic acid itself has the same effect. Was revealed.

The following mechanism can be considered as a mechanism in which oxygen is contained in Fe plating. That is, the carboxylic acid in the plating solution lowers the pH of forming hydroxide of Fe ³⁺ , and the Fe ³⁺ is present in the plating bath in a dissolved state without precipitating, and this Fe ³⁺ is present in the vicinity of the cathode. It is considered that the pH rises due to the generation of hydrogen and turns into hydroxide on the electrodeposits and is taken in in the form of being involved in the Fe plating. Normal Fe plating, ie
In the case of Fe plating where the concentration is not controlled without intentionally adding Fe ³⁺ ions to the plating solution, hydroxide formation of Fe ²⁺
Since the pH is high, no hydroxide is formed on the deposit, and the metallic iron is directly deposited, so that oxygen is not taken into the plating layer. Therefore, in order to contain oxygen in the Fe plating, Fe ³⁺
Must be present, and this Fe ³⁺
A carboxylic acid is required to prevent precipitation in the Fe plating bath. When both Fe ³⁺ and carboxylic acid are not present, the oxygen concentration cannot be controlled within the oxygen concentration range necessary for improving the plating property in the present invention.

In the present invention, although the concentration of the carboxylic acid or its metal salt to be put into the Fe plating bath is not particularly limited, it is 1 to 10
A concentration range of 0 g / l is practical and desirable.

As the Fe plating bath, the oxygen concentration in the plating layer can be controlled by controlling the Fe ³⁺ concentration and adding a carboxylic acid or a metal salt of a carboxylic acid, and other conditions are not particularly limited. As the plating bath, both a sulfuric acid bath and a chloride bath are possible, and other Fe plating baths are also possible.
In the plating bath, Fe ²⁺
It is desirable that Fe having a concentration of about 20 to 100 g / l be added in the form of sulfate or chloride. Further, in order to increase the current efficiency, a conductive assistant such as sodium sulfate may be added.

The temperature of the plating solution is preferably in the range from room temperature to 80 ° C., and is preferably 40 to 60 ° C. industrially. There is no problem if the pH is in the range of ordinary acidic bath Fe plating.

In the present invention, since a carboxylic acid or an alkali metal salt of a carboxylic acid is added to the Fe plating bath, the Fe plating layer contains a trace amount of carbon in addition to the above-described oxygen. In the case of the present invention, 0.01 wt% or more and less than 10 wt% of carbon are contained.
In the present invention, the oxygen-containing Fe
We also provide plated original sheets for surface-treated steel sheets with few plating defects.

The oxygen-containing Fe plating generated on the steel sheet in this way needs to be reduced in an annealing step in a continuous hot-dip plating line or an annealing step performed prior to electroplating. Any condition can be used as long as it is sufficiently reduced. As the atmosphere gas, hydrogen alone or a mixed gas of hydrogen and nitrogen, argon, or the like can be used, but 3 to 25% hydrogen gas is practically used industrially. The annealing temperature varies depending on the type of steel, but in the case of a cold rolled steel sheet, it is preferably 700 ° C. or more, and the annealing time is preferably 10 seconds or more.

According to the method disclosed in the present invention, when hot-dip coating is performed on a high-strength steel sheet, it is possible to obtain a plating free of non-plating.However, the hot-dip coated steel sheet subjected to the pretreatment can be easily obtained in a temperature range of about 450 to 550 ° C. It is possible to obtain an alloyed hot-dip galvanized steel sheet of a high-tensile steel sheet material. Si, P, Mn significantly slows alloying rate
When hot-dip galvanizing without applying Fe plating, it is difficult to alloy at a temperature range of 550 ° C or less, and it becomes alloyed at around 600 ° C. However, in the present method, the alloying temperature can be reduced by the oxygen-containing Fe plating, so that it is possible to obtain an alloyed hot-dip galvanized steel sheet of a high-tensile steel sheet material having good adhesion. The alloying temperature varies depending on the amount of plating applied, the line speed, and the like, but it is desirable that the alloying temperature be as low as possible in order to obtain GA with good adhesion.

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

(Example 1) C: 0.002 wt%, Si: 1.0 wt%, Mn: 3.0 wt%, P: 0.15 wt%
The contained steel was melted and subjected to hot rolling and cold rolling according to a conventional method to produce a steel sheet having a thickness of 0.7 mm. This cold-rolled steel sheet was subjected to degreasing and pickling treatments, and then subjected to electroplating baths and plating conditions shown in Tables 1 and 2 to apply Fe plating having the adhesion amount and oxygen content shown in Table 3 to the steel sheet as a cathode, Pb Was used as an anode.
The oxygen content in the Fe plating layer was determined from the difference in the amount of oxygen between the Fe-plated steel sheet and the untreated steel sheet and the amount of Fe plating attached.

The above steel sheet is treated under the following (A) annealing conditions,
(B) Ga treated under hot-dip plating conditions and (C) alloying conditions
GIs obtained by treating the GI under the hot-dip plating conditions were referred to as Invention Examples 1-4. Further, (A) a steel sheet treated under annealing conditions is replaced with (D) a Zn—Ni treated under electroplating conditions.
The plated steel sheet was designated as invention example 1-5.

The annealing and hot-dip galvanizing were performed by a hot-dip plating simulator, and the alloying treatment was performed by a laboratory using an infrared heating furnace. In addition, electroplating
Laboratory performed by fluidized-bed plating.

As a comparative example, a steel sheet having the same steel sheet composition as that used in the above invention example and not subjected to oxygen-containing Fe plating (Comparative Example 1-1), and an oxygen concentration in the plating layer and an amount of attached Fe outside the range of the present invention. Plated steel sheet (Comparative Examples 1-2 to 1-
6), further containing no strongly oxidizable element C: 0.
A steel sheet having a chemical composition of 002 wt%, Si: 0.01 wt%, Mn: 0.1 wt%, and P: 0.01 wt% (Comparative Examples 1-7) was annealed, and Ga, GI, Zn- Tables 2 and 3 show the Ni-plated steel sheets.

 The following evaluations were performed on these inventive examples and comparative examples.

(A) Annealing conditions Heating rate: 10 ° C / sec Holding temperature: 850 ° C Holding time: 30 sec Cooling rate: 20 ° C / sec Atmosphere in annealing furnace: 5% H ₂ -N ₂ (dew point −20 ° C) (B) Hot-dip plating conditions Bath temperature: 470 ° C Penetration plate temperature: 470 ° C Al content: 0.15wt% Coating weight: 60g / m ² (one side) Plating time: 1sec (C) Alloying condition Heating rate: 20 ° C / sec cooling rate: 15 ° C. / sec alloying temperature: 490 ° C. alloying time: 30 sec (D) electroplating conditions baths _{ZnSO 4 200g / l NiSO 4 80g} / l Na 2 SO 4 50g / l DK 100A / dm 2 pH 1.8 Bath temperature 60 ° C. Adhesion amount 30 g / m ² Ni content 12 wt% (Plating property evaluation method) Plating property was determined according to the following criteria by visual judgment of the outer tube after galvanizing.

○ No plating × No plating (Evaluation of plating adhesion) Evaluated by Dupont impact test (1/4 inch, 1 kg, 50 cm). The criteria are as follows.

○ No plating peeling × Plating peeling (Evaluation of alloying speed) The alloying speed was evaluated based on whether or not the zinc η phase remained on the surface of the alloyed material treated under the above conditions.

○ Without zinc η phase × With zinc η phase Table 3 shows the evaluation results of Invention Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-7. From this investigation, it was found that the method disclosed in the present invention showed that even steel sheets containing highly oxidizable elements such as Si, Mn, P, Ti, Nb, Al, Ni, Cu, Mo, V, Cr, and B were not affected. It is possible to manufacture galvanized steel sheets with excellent adhesion without plating, and in the case of galvannealed steel sheets,
It was shown that the alloying speed was moderately promoted and that the alloy could be produced by a method similar to the conventional method.

(Example 2) Steel containing the component elements having the concentrations shown in Table 4 was melted and subjected to hot rolling and cold rolling according to a conventional method to produce a steel sheet having a thickness of 0.7 mm. After subjecting this cold-rolled steel sheet to degreasing and pickling treatments, the electroplating bath and plating conditions shown in Tables 5 and 6 were used.
Fe plating of the adhesion amount and oxygen content shown in Table 7 was performed using a steel plate as a cathode and Pb as an anode. The oxygen content in the Fe plating layer is determined by the difference in oxygen content between the Fe-plated steel sheet and the untreated steel sheet.
It was determined from the coating weight.

In the same manner as described above, GAs treated with (A) annealing conditions, (B) hot-dip plating conditions, and (C) alloying conditions were applied to the above-mentioned steel sheets to Invention Examples 2-1 to 2-3 and 2-6. , 2-7, (B)
The GI treated under the hot-dip plating conditions was designated as Invention Example 2-4. In addition, (A) a Zn-Ni-plated steel sheet treated under annealing conditions (D) and a steel sheet treated under annealing conditions was defined as Invention Example 2-5.

The annealing and hot-dip galvanizing were performed by a hot-dip plating simulator, and the alloying treatment was performed by a laboratory using an infrared heating furnace. In addition, electroplating
Laboratory performed by fluidized-bed plating.

As a comparative example, the steel sheet containing the elemental elements having the concentrations shown in Table 4 was not subjected to the oxygen-containing Fe plating (Comparative Example 2-1), and the oxygen concentration in the plating layer and the adhesion amount were within the scope of the present invention. Deviated Fe-plated steel sheet (Comparative Example 2-2)
To 2-7) are subjected to an annealing treatment, respectively, and
Table 7 shows the steel sheets subjected to GA, GI, and Zn-Ni plating.

The same evaluation as in Example 1 was performed on these inventive examples and comparative examples.

Table 7 shows the evaluation results of Inventive Examples 2-1 to 2-7 and Comparative Examples 2-1 to 2-7. From this study, the method disclosed in the present invention makes it possible to produce a galvanized steel sheet with excellent adhesion without non-plating even in steel sheets containing highly oxidizable elements such as Si, Mn, and P. In addition, in the case of an alloyed hot-dip galvanized steel sheet, it was shown that the alloying speed was moderately promoted and the alloying hot-dip galvanized steel sheet could be manufactured by the same method as the conventional method.

(Example 3) A steel having a concentration of a component element shown in Table 8 was melted and subjected to hot rolling and cold rolling according to a conventional method to produce a steel sheet having a thickness of 0.7 mm. This cold-rolled steel sheet was degreased and pickled, and then subjected to electroplating baths and plating conditions shown in Tables 9 and 10 to obtain a table.
Fe plating of the adhesion amount and oxygen content shown in 11 was performed using a steel plate as a cathode and Pb as an anode. The oxygen content in the Fe plating layer was determined from the difference in the amount of oxygen between the Fe-plated steel sheet and the untreated steel sheet and the amount of Fe plating attached.

In the same manner as described above, GA treated with (A) annealing conditions, (B) hot-dip galvanizing conditions, and (C) alloying conditions was applied to the above steel sheets. , 3-7,
(B) The GI treated under the hot-dip plating conditions was defined as Invention Example 3-4. In addition, (A) a Zn-Ni plated steel sheet treated under annealing conditions (D) was used for a steel sheet treated under annealing conditions.
And

The annealing and hot-dip galvanizing were performed by a hot-dip plating simulator, and the alloying treatment was performed by a laboratory using an infrared heating furnace. In addition, electroplating
Laboratory performed by fluidized-bed plating.

As a comparative example, a steel sheet (comparative example 3-1) having the same steel sheet composition as that used in the above invention example but not subjected to oxygen-containing Fe plating, and an oxygen concentration in the plating layer and a deposition amount deviating from the range of the present invention. Plated steel sheet (Comparative Examples 2-2 to 3-
6), further containing no strongly oxidizable element C: 0.
002 wt%, Si: 0.01 wt%, Mn: 0.1 wt%, P: 0.01 wt% of the steel composition (Comparative Examples 3-7) were annealed, and GA, GI, Zn- Table 11 shows the steel sheets plated with Ni.

The same evaluation as in Example 1 was performed on these inventive examples and comparative examples.

Table 11 shows the evaluation results of Inventive Examples 1 to 7 and Comparative Examples 1 to 7. From this study, it was found that Si, Mn,
Even for steel sheets containing highly oxidizable elements such as P, Ti, Nb, Al, Ni, Cu, Mo, V, Cr, and B, it is possible to manufacture galvanized steel sheets with excellent adhesion without non-plating. Is possible,
In the case of an alloyed hot-dip galvanized steel sheet, it was shown that the alloying speed was moderately accelerated, and that the steel sheet could be manufactured by a method not different from the conventional method.

INDUSTRIAL APPLICABILITY When zinc or zinc-based alloy plating is performed on high-strength steel sheets, the present invention enables low-cost and stable production of zinc or zinc-based alloy plating with excellent adhesion without non-plating. Becomes In the case of performing the alloying treatment, an alloyed hot-dip galvanized steel sheet can be obtained at a relatively low temperature.

With the urgency of reducing the weight of automobiles, the development of hot-dip galvanized steel sheets, alloyed hot-dip galvanized steel sheets, and electro-galvanized or zinc-based alloy-coated steel sheets has been desired in recent years, contributing to the industry of the present invention. Is extremely large.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shigeru Umino 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Engineering Co., Ltd.

Claims (12)

(57) [Claims] 1. A steel sheet comprising a steel sheet having a galvanized layer or a zinc-based alloy plating layer adhered to at least one surface of the steel sheet.
A surface-treated steel sheet having a small number of plating defects, comprising a plating layer and a concentrated layer of a component in steel immediately below the Fe plating layer. 2. The method according to claim 1, wherein the concentrated layer immediately below the Fe plating layer comprises Si, Mn, P, T
2. The surface-treated steel sheet according to claim 1, wherein the surface-treated steel sheet is composed of at least one selected from the group consisting of i, Nb, Al, Ni, Cu, Mo, V, Cr and B. 3. Si, M having the following concentration range as a component element in steel.
2. The surface-treated steel sheet having few plating defects according to claim 1, comprising at least one of n and P. 0.1wt% ≤ Si ≤ 2.0wt% 0.5wt% ≤ Mn ≤ 4.0wt% 0.05wt% ≤ P ≤ 0.2wt% 4. The surface-treated steel sheet having few plating defects according to claim 1, wherein the amount of the Fe plating layer attached is 0.1 to 10 g / m ² . 5. A Fe plating wherein the concentrated layer immediately below the Fe plating layer has an adhesion amount of at least 0.1 to 10 g / m ^{2 on} at least one surface of the steel sheet and an oxygen content in the plating layer of 0.1 to 10 wt%. After applying
The surface-treated steel sheet having few plating defects according to any one of claims 1 to 4, wherein the surface-treated steel sheet is formed by performing an annealing treatment. 6. The method according to claim 6, wherein an adhesion amount of 0.1%
To 10 g / m ² a and the oxygen content in the coating layer is 0.1-10%
A method for producing a surface-treated steel sheet having a small number of plating defects, characterized by performing an annealing treatment after applying Fe plating, and then performing zinc or zinc-based alloy plating. 7. The steel sheet to be subjected to Fe plating is made of Si, Mn, P, Ti, N
b, Al, Ni, Cu, Mo, V, Cr and at least one selected from the group consisting of B, Si, Ti, Ni, Cu, Mo, Cr and V are 0.1 wt%
7. The method for producing a surface-treated steel sheet according to claim 6, wherein Mn contains 0.5 wt% or more, P, Al and Nb contain 0.05 wt% or more, and B contains 0.001 wt% or more. 8. The surface treatment with few plating defects according to claim 6, wherein the steel sheet to be subjected to Fe plating contains at least one of Si, Mn and P in the following concentration range as a component element in the steel. Steel plate manufacturing method. 0.1wt% ≤ Si ≤ 2.0wt% 0.5wt% ≤ Mn ≤ 4.0wt% 0.05wt% ≤ P ≤ 0.2wt% 9. The method according to claim 6, wherein the electroplating bath for Fe plating contains Fe ³⁺ of 0.1 g / l or more and contains a carboxylic acid or an alkali metal salt of a carboxylic acid. Manufacturing method of surface treated steel sheet with few plating defects. 10. An electroplating bath for Fe plating, wherein the electroplating bath is 0.1-2.
The method for producing a surface-treated steel sheet having a small number of plating defects according to any one of claims 6 to 8, comprising 0 g / l of Fe3 ⁺ and containing a carboxylic acid or an alkali metal salt of a carboxylic acid. 11. An electroplating bath for Fe plating, comprising:
The method for producing a surface-treated steel sheet having a small number of plating defects according to any one of claims 6 to 8, comprising 0 g / l of Fe3 ⁺ and containing a carboxylic acid or an alkali metal salt of a carboxylic acid. 12. The method according to claim 1, wherein at least one surface of the steel sheet has an adhesion amount of 0.
1 to 10 g / m ² and the oxygen content in the plating layer is 0.1 to 10 wt%
An original plate for a surface-treated steel sheet having few plating defects, characterized by being subjected to Fe plating.