JP2726008B2 - High performance Sn-based multi-layer plated steel sheet with excellent corrosion resistance, weldability and paint adhesion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to, for example, cans (containers).
The present invention relates to a surface-treated steel sheet that is suitable for use as a steel sheet. [0002] 2. Description of the Related Art In recent years, a can-making system for food cans,
Inns have significantly advanced and diversified,
There has been a growing demand for surface treated steel sheets for cans. this
The requirements are welding cans, (Japanese Unexamined Patent Publication No. 55-41905
6-55590) Notable in easy-open can lids
is there. [0003] Welded cans have high joint strength and poor joints.
Is very low, and the joint
The cost is small and the appearance is beautiful, and the amount of can-making equipment investment
It is rapidly evolving from the advantages such as the need for less. [0004] On the other hand, the easy open can lid has a can opener.
A place that can be easily opened anytime and anywhere without need
Almost 100% are used in beverage cans.
It is considered to be used for all food cans. [0005] At present, Al plates have excellent openability.
Often used for easy open can lid materials
Al is used for treated steel sheet (tin) due to corrosion resistance.
Food that does not come (for example, food containing salt, such as tomato juice)
Product). However, recently, steel plate materials and can lid
As a result of consideration from the aspect of Zine, the can open is not inferior to Al plate
Easy-open tin lid of tin plate can be manufactured
New materials that can further reduce the price of cans
Was. [0006] The material for welding cans has excellent weldability.
Of course, it has excellent paintability and corrosion resistance after painting
Things are also required. Easy open can lid makes opening cans easy
And open the mouth large enough to remove the contents
In order to put a V-shaped notch on the surface,
The overhang of the tab, which serves as the starting point for tearing the opening, and the aperture
Processing, caulking to fix the tab to that part, so-called Ribe
Severe processing such as cut processing is performed. Therefore, easy
The open can lid material has not only the workability of the steel plate itself, but also
The following performance is also required of the surface coating layer. (A) Riveting and scoring
The coating layer does not crack, and if
Do not reach iron. (B) Does not degrade the coating performance of the processed part
Thing. In addition, as a whole, paintability and post-paint resistance
It is also required to be excellent in food quality. Also, Easy
For can lids and can bodies other than open can lids,
Since severe processing is performed, bending parts etc.
However, the same characteristics as above are required. [0010] In order to meet the above demands, welding
For cans # 25 or # 50 tin (Sn plating 2
800mg / m^Two , 5600mg / m^Two ), Easyo
# 25- # 75 tin for open cans (Sn plating amount 2
800-8400mg / m^Two) Etc. have been used,
Higher tin price makes it more expensive and less expensive
Materials with superior performance have been strongly demanded. [0011] SUMMARY OF THE INVENTION Under such circumstances, the present invention
It is clear that the performance of the material for welding cans has been further improved and
Can be used as a can open lid or a regular can lid
Inexpensive alternative to tin with high Sn adhesion
As a result of various studies for the purpose of material development, high-performance Sn-based
This is a multi-layer plated steel plate developed. [0012] SUMMARY OF THE INVENTION The present invention provides a steel plate having
On the opposite side of the steel sheet, a Ni--Fe alloy having a Ni concentration of 10% or less is coated.
A Ni-Fe-based alloy having a cover layer on the steel sheet side;
Ni-Fe based alloy with Ni concentration exceeding the Ni concentration of the coating layer
Ni-Fe having a coating layer and being opposite to the steel sheet side and the steel sheet side
Structure N in which the average Ni concentration of the base alloy coating layer is less than 20%
i-Fe-based alloy coating layer, the two-layer Ni-Fe-based alloy coating
Sn coating layer on top of covering layer, chromate based on top layer
Corrosion resistance, weldability and coating characteristics characterized by forming a treatment layer
High performance Sn-based multi-layer plated steel sheet with excellent mounting adhesion
You. In particular, the formation of the above-mentioned coating layer is carried out by a usual tinplate.
Heat melting process (so-called melt process) in the steel sheet manufacturing process
Treatment), a two-layer Ni-Fe alloy base coat treatment, Sn plating
By following the gating treatment, Ni-Fe alloy
A uniform and dense alloy layer is formed by a diffusion reaction with Sn.
By improving, the performance is further improved. Thus, the steel sheet provided with the coating treatment layer of the present invention
Is melted by the electric resistance welding method used after painting.
Easy open can lid which receives contacting or severe processing
The present invention has the following features. (A) Ni having an average Ni content of less than 20%
When the Sn plating layer is coated on the Fe-based alloy coating layer, as shown in FIG.
As shown, the uniform coverage of Sn is significantly increased. (Figure 1
Is the average Ni concentration of the Ni-Fe alloy plating layer and the IEV
(Iron ExposureValue = iron exposure)
As a result, the number of Sn pinholes is small.
Therefore, the effect of improving the corrosion resistance is remarkable, and
The effect is particularly remarkable when the cover layer is coated. (B) Paint baking treatment (160 to 220 ° C.)
Or about 10 to 60 minutes) or melt treatment after Sn plating
The resulting Sn-Ni alloy layer is
Fe-Sn alloy when Sn plating is applied directly to the ground
Compared to the layer, it is very uniform and dense as shown in FIG.
You. As a result, the number of pinholes in the alloy layer decreases, and Sn
Dissolution rate is reduced, and corrosion resistance life is extended even with low Sn deposition
(Fig. 2 (a) shows the Ni-Fe alloy plating layer
Average Ni concentration and ATC(Aloy-TinCoup
letest = alloy layer-tin connection current measurement test)And Sn
FIG. 3B shows the relationship with the amount of elution, and FIG.
The relationship between the average Ni concentration in the plating layer and the amount of Sn eluted is shown.
Figure). (C) The Ni—Fe alloy coating layer and Sn
Since the alloy layer generated during the process is uniform and fine, baking paint etc.
Suppresses the formation of Sn diffusion alloy layer when subjected to heat treatment
Effect is large, and the uncoated Sn coating layer (free)
Sn layer) tends to remain as shown in FIG. 3 (FIG. 3 shows Ni-
Average Ni concentration in Fe alloy plating layer and flow after baking
FIG. 4 is a diagram showing the relationship with the remaining amount of Lee Sn). As a result, due to the residual effect of free Sn,
Improves weldability. Severe processing such as rivet processing and score processing
Again, the effect of preventing the occurrence of cracks is great. Even if cracks occur, each coating layer
Since the crystal structure and hardness are different,
Propagation stops at the boundary of each layer (steel surface), maintaining corrosion resistance
Is done. In the case of comparison between plated steel sheets having the same Sn adhesion amount,
In the case of scratches or defects in the coating layer in the can manufacturing process,
The anticorrosion effect is as much as free Sn remains as in the present invention.
And the Sn metal itself in a corrosive environment
The effect of extending the corrosion life is extended because the time until the battery disappears
Is obtained. Further, the present invention will be described in detail. In the present invention, thin steel sheets are currently used in the steel industry.
Tinplate and tin-free stee widely used
(TFS) manufactured for surface-treated steel sheets
Eg cold rolling, annealing temper rolling or second cold pressing
Each rolled and adjusted as an original sheet for surface treated steel sheet
A kind of cold rolled steel sheet is used. [0024] The steel sheet is currently in the pretreatment immediately before the production of the surface-treated steel sheet.
After alkali washing and pickling to activate the surface, Ni
-Fe alloy plating is applied. Ni-Fe alloy plating
The baths are sulfate bath, chloride bath, sulfate-chloride bath, cyanide
Bath, citric acid bath, pyrophosphate bath, etc.
Bath, sulfate-chloride bath, or chloride-based bath
Suitable for workability and cost. For example, iron sulfate-nickel sulfate-sodium acetate
ー －Sulfuric acid sorter bath or iron sulfate－nickel sulfate－
A nickel chloride-boric acid bath or the like is used. Thus, Ni-Fe alloy plating undercoating
The coating composition of the layer has an average Ni content of less than 20%, preferably
Is the composition of a Ni—Fe-based alloy film having a Ni content of less than 15%.
You need to use something. Average Ni content is 20% or more
Then, when heat treatment such as paint baking is performed, Sn
The alloying reaction containing Ni becomes remarkable due to the diffusion reaction.
The uniform denseness of the resulting alloy layer increases,
(The so-called ATC value decreases), but remains free.
Since the existing Sn coating layer is reduced, it has good weldability and corrosion resistance life.
Not good. From the above points, the average Ni content is less than 20%.
Full, preferably 10% or less, of the Ni-Fe alloy coating layer
Selected. The lower limit of the average Ni content is 0.5% or less.
Above, preferably used in the range of 2% or more,
If the average Ni content is less than 0.5%, it may react with Sn.
There is a tendency for the uniform denseness of the resulting alloy layer to deteriorate. What is important in the present invention is the Ni--Fe system.
The structure of the alloy undercoat layer is changed to Ni in contact with the Sn plating layer.
The Ni content on the surface side (anti-steel side) of the Fe-based alloy layer is 1
0% or less, and the steel surface of the lower steel (steel side)
By increasing the Ni content of the contacting coating layer, a two-layer Ni-
Maintain the average concentration of the Fe-based base alloy layer at less than 20%.
And In this case, heat treatment at the time of baking paint with Sn
The growth of the alloy layer produced by the surface contacting Sn
And free Sn remains suppressed due to low Ni concentration
The amount increases. On the other hand, a large amount of Ni content generated on the lower surface side
The alloy layer composed of Sn, Fe, and Ni should be uniform and dense.
Produced in alloy layer with low runout, low ATC value and few pinholes
Is done. The Ni-Fe two-layer type Ni-Fe
Base alloy coating layer on steel sheet using the same plating bath composition
First, the current density was increased and Ni-Fe alloy plating was performed.
Next, lower the current density to Ni-Fe alloy plating
And is easily formed. Alternatively, control of the Ni ion concentration of the electroplating bath.
First, electrolytic treatment in a plating bath with high Ni concentration
And then plating with reduced Ni ion concentration
It can be easily formed by electrolytic treatment using a bath.
You. Further, a two-layer Ni--Fe as an undercoat layer
The coating amount of the base alloy layer is 10 to 500 mg / m^Two , Preferred
50 to 200 mg / m^Two It is preferable to use the one with an adhesion amount of This is because the coating amount is 10 mg / m^Two Less than
Makes it difficult to coat the surface of the steel sheet uniformly and stably
In some cases, the residual effect of free Sn which is the object of the present invention
Deteriorates uniform formation of dense alloy layer containing Ni and Ni
Tend to be. On the other hand, 500 mg / m^Two Beyond, two layers
Type Ni-Fe alloy coating layer is steel plate, Fe-Sn alloy
Since it is somewhat harder than the layer, bending, riveting
It is not preferable because cracks occur during construction
There are cases. Thus, this two-layer Ni—Fe alloy coating
The method of providing the layer is to make the steel sheet surface uniform with the amount of
Active surface after electroplating
Immediately by electroplating the Sn coating layer
-Layer Ni-Fe alloy to obtain a highly electrodeposited Sn coating layer
The coating layer is preferably applied by an electroplating method. This is shown in FIG.
As shown, heat diffusion treatment after Ni plating or Ni salt
Coated on the surface of a steel sheet and then subjected to a heat diffusion treatment to provide Ni-
An electric Sn plating layer was provided on the surface of the Fe-based alloy coating layer.
In the case, that is, the uniform covering property of the electric Sn plating layer is measured.
(FIG. 4 shows various types of Ni—Fe undercoating and IEV
FIG. Ni-Fe alloy by electroplating
Immediate uniform coverage of the Sn coating layer provided on the gold base coating layer
It is clear that it is. In addition, it cannot be included in the Ni—Fe alloy base coat layer.
Co, Sn, etc. contained as evasive impurities
Neither does it hinder the effects of the present invention. Next, these two-layer type Ni—Fe alloys
After the undercoat layer is applied, after washing with water, the Sn plating upper layer
Do the lock. This Sn plating method is the method, electrolytic treatment
It does not prescribe any conditions, etc.
There are ferrostan bath, halogen bath, widely used
Or any of the other Sn electroplating baths.
No. The amount of Sn plating is not particularly specified.
However, in the case of a low Sn deposition amount, the lower two-layer type Ni-F
Uniform and dense alloy layer by the effect of e-base alloy undercoat layer
Generation, more than free Sn coating layer, Sn
Excellent corrosion resistance due to the remarkable improvement of the throwing power of the coating layer
, Weldability, and corrosion resistance life extension.
n attached amount 2500mg / m^Two Or less, preferably 1500
mg / m^Two The following Sn adhesion amount is applied,
The effect is great and economically desirable. The lower limit of the amount of Sn adhesion is that the underlayer has two layers.
Type Ni-Fe alloy coating layer
When subjected to heat treatment in the can process, free Sn
Low residual coating amount, poor corrosion protection of plating defects
That the coating layer contains almost Ni, Fe, Sn
Since the free Sn coating amount is large,
Contact resistance is high and weldability is poor.
From the title, 500mg / m^Two Above, preferably 600mg
/ M^Two The above is good. In the present invention, after Sn plating and washing with water,
Chromate treatment may be performed.
Before the treatment, the processing performed in the normal tin manufacturing process
A heat melting treatment (melt treatment) may be performed. In particular, the book
By carrying out this melt treatment in the invention,
Heat treatment such as paint baking without using
In a state where Sn is molten,
To react with the Ni-Fe alloy coating layer in a short time,
ATC value is probably because a uniform fine alloy layer is generated
Extremely low and heating in the can making process
This alloy layer expands the surface of the steel sheet and the plating layer Sn for the treatment.
The effect of preventing the decrease of free Sn by forming a scattering inhibition layer
This is extremely advantageous in terms of weldability and corrosion resistance.
In addition, the uniform and dense alloy layer
The elution rate of Sn in a corrosive environment by improving the ATC value
Becomes smaller, so that the
Is also advantageous. In this melt treatment, after passing through the Sn plating,
Usually, it is immersed in a solution with a reduced plating bath concentration to
The solution is applied to the Sn plating surface as flux and melted by heating.
Is melted. In the present invention, a base Ni-Fe alloy coating layer
Due to the effect of this method, the appearance becomes dark glossy with this method.
Therefore, instead of the solution, 1/1 of tap water or plating bath
Immersion in a dilute solution of 0 or less
Is particularly preferred since the appearance becomes white glossy. Next, chromate is applied to the surface of the Sn plating layer.
System processing is performed. After applying the upper plating of Sn, the coating property is further improved.
And chromate treatment to improve coating film performance.
You. The chromate coating improves the adhesion of paint for cans and
On the surface, the contents of the aqueous solution penetrate the coating film and
So-called corrosion progresses at the coating film interfaceUndercuttin
GukorosionIt has a great effect on preventing. Like this
For a long period of time, the adhesion of
Food habit is maintained. Chromate coatings also contain S compounds.
Of steel plates in the case of foodstuffs such as fish meat and livestock products
The effect of preventing blackening of the surface, that is, blackening of sulfurized black, is great. Scratch
Chromate coatings are particularly suitable for painting.
Is effective for improving the performance, but harmful to welding.
is there. The chromate film referred to here is hydrated chromium oxide
One film, the original chromate film, and another, the lower layer
Two-layer coating of metallic Cr and hydrated chromium oxide on it
In two cases. Hydrated chromium oxide coating is electrical
Is an insulator and has a high electrical resistance.
High resistance and melting point, all degrade weldability
Tend to be. Thus, in the present invention, the use for welding cans is
In the case of the target, the amount of Cr attached was
5 to 20 mg / m per surface^Two , Preferably 7.5 to 15 m
g / m^Two Is selected. In addition, severe additions such as can lids
It does not use welding or soldering.
For use, 5 to 50 mg / m^Two , Preferably 7.5-3
5mg / m^Two Is selected. That is, the amount of Cr attached was 5 mg / m²Less than
Is to improve paint adhesion,Undercutting Collage
® downNo effect is obtained in preventing corrosion under the coating film, etc.
mg / m²The above Cr adhesion amount is preferably 7.5 mg.
/ M²The above amount of adhesion is good. In the case of welding cans, Cr
20mg / m^Two Beyond this point, the contact resistance increases significantly.
Therefore, it is necessary to increase the welding current,
Weldability is reduced because the welding range becomes narrower, such as in the
Deteriorates. Therefore, the amount of Cr attached is 20 mg / m^Two
Or less, preferably 15 mg / m^Two The following is good. Less than welding can
When used for other applications outside, C
It is preferable that the r adhesion amount is large, but the Cr adhesion amount is 50 mg.
/ M^Two If it exceeds, the appearance deteriorates (yellow coloring or blackish
40mg / m^Two below
The amount of Cr attached is preferred. In the chromate treatment, chromic acid, various chromate
With aqueous solution of Na, K or ammonia salt of humic acid
Any method such as immersion, spray treatment, cathodic electrolytic treatment, etc.
However, the cathodic electrolytic treatment is excellent. Above all, C
rO_Three To SO_Four Ion, F ion (including complex ion)
Or cathodic electrolysis in an aqueous solution to which these mixtures have been added.
Is the best way. CrO_Three The concentration of
A range of 100 g / l is sufficient, but there is no
Absent. The amount of anions to be added depends on the hexavalent chromium ion concentration.
1/300 to 1/25 of degree, preferably 1/200 to 1 /
At a concentration of 50, the best chromate coating is obtained. shadow
Uniform and uniform when the ion concentration is 1/300 or less of Cr
Quality chromate coating, which greatly affects coating performance.
It becomes difficult to obtain a film. At 1/25 or more, the chroma
The amount of anions incorporated in the coating increases,
Performance deteriorates. There is no need to regulate the bath temperature.
The range of 0 to 70 ° C. is appropriate from the viewpoint of workability. Cathodic electricity
Dissolution current density is 5 to 100 A / dm^Two Is sufficient
You. The processing time depends on any combination of the above processing conditions.
Therefore, as shown above, the amount of chromate
Corresponding 5-20mg / m^Two Set to be within the range
You. In particular, in the present invention, CrO_Three In solution
SO_Four ^-2 Or F^- Add ions in the above range and set the current density
50A / dm^Two ~ 100A / dm^Two Less than 0.2 seconds
It is preferable to perform time processing. By this processing, as shown in FIG.
r layer is 5 to 15 mg / m on the Sn plating layer^Two Precipitates out
Chromium oxide hydrate is formed on the upper layer of chromium oxide.
You. This hydrated chromium oxide layer is used in the solution after electrolytic treatment.
Adjust the immersion time or concentrate in a separate treatment tank.
CrO of different degrees_Three -By dissolution treatment in an anionic bath, etc.
(FIG. 5 shows a chromate electrolytic treatment).
FIG. 4 is a diagram showing the relationship between the processing conditions and the amount of chromium deposition). The deposition of the metal Cr layer is uniform on the Sn surface.
The painting performance has been significantly improved by
After the Sn plating, melt treatment
Those that have been subjected to a grease treatment further improve the coating performance
New This is when used as a container material.
Environment containing an aqueous solution of an organic acid such as citric acid
Then, for the corrosive aqueous solution entering through the coating film, S
Since the progress of corrosion under the coating of n metal is relatively remarkable,
Corrosion aqueous solution reaches the Sn metal surface by providing a deposited metal Cr layer.
It is preferable because it can be suppressed. Thus, the above adhesion
In the range of the amount, in this two-layer type chromate coating,
The ratio of the metal Cr layer to the oxide chromium layer is 0.6 ≦ oxa
The range of id chromium / chromium metal ≦ 3 is preferred. That is, compared to the amount of metallic Cr,⁺³chromium
Oxides mainly composed of hydrated chromium oxide and
If the amount of chromium is small,
Poor adhesion of paint due to poor uniform coverage
There is a tendency. In addition, compared to the metal Cr layer,
When the amount of the oxide layer is large, it is contained in the oxide chromium layer.
Anion, Cr⁺⁶Increased ions, hot rot after painting
Due to elution of these anions when exposed to the food environment, etc.
Small blisters (so-called blisters) occur under the coating film
It is not preferable because it becomes easy. Therefore, the oxide chromium and the metal chromium
The composition ratio is 0.6 to 3 times as described above, preferably 1.0
It is preferable to set the range to 2.5 times. Further, when a melt treatment is performed,
A trace amount of Ni metal diffuses and precipitates on the Sn plating layer surface
Therefore, in the chromate treatment of the above film configuration,
Adhesive improvement is remarkable and progress of under-film corrosion is suppressed.
Is particularly preferred. Anions added to the treatment bath
Compound of sulfuric acid, chromium sulfate, ammonium fluoride, sodium fluoride
It is added to the chromic acid bath in the form of a substance. As described above, the surface-treated steel sheet of the present invention is currently
Various continuous plating equipment used in tinplate manufacturing
Ni-Fe plating equipment or Ni plating equipment
Can be manufactured efficiently with the equipment
You. A Ni—Fe alloy layer was formed on the surface of the steel sheet.
In addition, regarding the method of further applying Sn plating thereon,
Is known to. All of these methods use N
Apply i-plating or apply an aqueous solution of Ni salt
After heating, the Ni plating layer on the steel sheet surface is diffused into the steel.
Or Ni reduced by decomposition and reduction of Ni salt into steel sheet
To form a Ni-Fe alloy layer.
Things. Therefore, Ni can be diffused into steel in a short time.
May need to be heated above the recrystallization temperature of the steel
Heating is also used for annealing, followed by temper rolling.
is necessary. Diffusion layer or N formed by temper rolling
The i-Fe alloy layer is considerably damaged, and the corrosion resistance is deteriorated.
Occurs. Diffusion by heating depends on the heating conditions (temperature, time
Affected, atmosphere, etc.) and stable alloy composition and coating thickness
It is hard to get things. Further, diffusion is selected at grain boundaries on the steel surface.
Strong tendency to proceed selectively, poor uniformity of alloy layer coating
Become. As described above, the present invention is compared with the conventional method.
The method is electroplating on the steel sheet surface after annealing and temper rolling.
Therefore, since the two-layer type Ni-Fe alloy layer is applied,
Uniform and stable coating of any alloy composition to any thickness
Better performance.
It is. Hereinafter, embodiments of the present invention will be described. (A) is shown on the surface of the cold-rolled steel sheet whose surface has been cleaned.
Under the conditions, the two-layer Ni-Fe binary alloy
A predetermined amount was formed by the g method. Subsequently, under the condition shown in FIG.
A predetermined amount of the Sn coating layer was provided. Then at 260 ° CnumberSecond
Melt treatment is performed during or between (C)
Perform the electrolytic chromate treatment under the conditions, and further apply the oil.
And subjected to various evaluation tests. [0063]   (A) Ni-Fe alloy base coat treatment     Plating bath composition NiSO_Four ・ 6H_Two O 75g / l                   NiCl_Two                     140g / l                   FeSO_Four ・ 7H_Two O 70-170 g / l                   (Change according to iron concentration)                   H_Three BO_Three                       45g / l     Plating bath temperature 50 ℃     Current density 15A / dm^Two ~ 3A / dm^Two In order to perform two-layer Ni-Fe alloy plating,
Performs high current density plating, and at the end of electrolysis,
The Ni content on the surface side (anti-steel side) is lowered
Side (steel plate side). [0064] (B) Sn plating coating treatment     Plating bath composition Tin sulfate 20-30g / l                   Phenolsulfonic acid 25-35 g / l                   (65% solution)     Plating bath temperature 50 ℃     Current density 15A / dm^Two  (C) Electrolytic chromate treatment   Treatment method (a): bath composition Na_Two Cr_Two O₇         25g / l                 Bath temperature 60 ℃ 5A / dm^Two ~ 8A / dm^Two For 2 seconds   Treatment method (b): bath composition 60 g / l CrO_Three -0.4 g / l SO_Four ^-2                  Bath temperature 50 ℃ At 10A / dm^Two Processing for 1 second   Treatment method (c): bath composition 100 g / l CrO_Three -0.6 g / l SO_Four ^-2                  Bath temperature 45 ° C 60 to 80 A / dm^Two , Process for 0.1 seconds Items [A] to [F] shown below for each of the treatment materials
And the performance was evaluated. [A] Uniform coverage of Sn plating layer 0.2mol sodium carbonate and 0.005mol saline
The solution was adjusted to pH 10 by adding sodium bicarbonate
Immerse plating sample (10 × 10mm) in test solution
And use a potentiostat to
Then, the anode side is subjected to 1.2 V constant potential electrolysis, and after 3 minutes
Current is measured and the uniform coverage of the Sn plating layer(IEV)To
evaluated. [B] Seam weldability Lapping 0.5mm, welding pressure 45ng, welding speed
Under the condition of 420 cans / min, changing the welding current
Minimum welding current and splash, etc., to obtain sufficient welding strength
The range of welding currents where the occurrence of welding defects begins to be noticeable
And comprehensively assess the occurrence of welding defects.
Was. [C] U.S. C. C.(Under Cu
tting Corrosion = undercutting
Gukorosion = corrosion under coating)Evaluation test Epoxy phenol (phenol-rich) paint for cans
50 mg / dm2 as dry weight per side²So that
Apply to the test surface of the sample and bake at 205 ° C for 10 minutes.
No further baking was performed at 180 ° C. for 20 minutes. And
Put a scratch on the painted surface with a knife and use a corrosion liquid (1.5%
(Citric acid-1.5% salt) and exposed to the atmosphere for 5 minutes.
After holding at 5 ° C for 4 days, scratch and flat the surface
Peeled off and the paint film on the scratch part was peeled off, scratch
Corrosion state (pitting) in part, and peeling of coating film on flat part
The detached state was determined. [D] Black sulfide resistance test Specimen coated in the same manner as in [C] is bent by 1t.
Immerse commercially available mackerel boiled in a homogenized mixer
It was immersed and subjected to a retort treatment at 115 ° C. × 90 mm.
After retort treatment, sulfide blackening of the bent part and flat part
evaluated. [E] Yarn rust resistance test Scratches with a knife on a specimen coated in the same manner as in [C].
Into the center of the test piece and stretch it 4 mm with an Erichsen tester.
After processing, 5% NaCl with a salt spray tester
Was sprayed for 3 hours. Then, the specimen was washed with water and dried, and then a dry bulb at 38 ° C. and a wet bulb.
Specimens in a thermo-hygrostat at 35.5 ° C and 85% relative humidity
And left for 60 days. And specimen coating scratch
Rust resistance by visually determining the occurrence of rust in the part
Was evaluated. [F] Performance evaluation of EOE processed material Inner surface corrosion resistance after easy open end (EOE) processing
For the purpose of evaluation of
45mg / dm2 epoxy / phenol paint²Nana
After painting, rivet processing and scoring
A processing (score thickness 75μ), about the counter sinker
And the crack occurrence status of each processed part,
C. After the test under the same conditions as the C test,
Observation and evaluation of the state of sub-film corrosion, same as [D] sulfide blackening test
Evaluation of blackening state of sulfide after evaluation test under one condition, and E
The test piece after OE processingIn a 5% NaCl solution at 125 ° C
1 hour immersion treatment (retort treatment)
Of the test specimenEach processing sectionCellophane adhesive tapeCelote
Soup(Registered trademark)PeelingdidPeeling status of paint film after
Is evaluated, and each evaluation result is comprehensively determined, and the EOE is evaluated.
Performance evaluation after processing was performed. [0072] [Table 1]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows average Ni concentration and IE of a Ni—Fe alloy plating layer.
FIG. 2A is a graph showing the relationship between the average N in the Ni—Fe alloy plating layer.
The figure which shows the relationship between i concentration and ATC and Sn elution amount,
FIG. 3B is a diagram showing the relationship between the average Ni concentration in the Ni—Fe alloy plating layer and the amount of Sn eluted. FIG. 3 is the average Ni concentration in the Ni—Fe alloy plating layer and the amount of free Sn remaining after baking. FIG. 4 is a diagram showing a relationship between various types of Ni—Fe base treatments and IEV, and FIG. 5 is a diagram showing a relationship between chromate electrolysis treatment conditions and chromium adhesion amount.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C25D 3/56 C25D 3/56 B (72) Inventor Hirofumi Nakano 1-1 Edamitsu, Yawata-Higashi-ku, Kitakyushu-shi -1 Inside Nippon Steel Corporation Yawata Works (72) Inventor Yachi Oyagi 1-1-1 Edamitsu, Yawata Higashi-ku, Kitakyushu City Inside Nippon Steel Corporation Yawata Works (56) References JP JP-A-60-17099 (JP, A) JP-A-57-200592 (JP, A) JP-A-55-69297 (JP, A) JP-A-52-95544 (JP, A)

Claims (1)

(57) [Claims] [1] A Ni-Fe-based alloy coating layer having a Ni concentration of 10% or less is provided on the steel sheet surface on the steel sheet side and on the steel sheet side, the Ni-Fe-based alloy coating layer is provided on the steel sheet side. An Ni-Fe alloy coating layer having a Ni concentration exceeding the Ni concentration of the alloy coating layer, and the average Ni concentration of the Ni-Fe alloy coating layer on the opposite side of the steel sheet and the steel sheet is 2
Less than 0% of a two-layer Ni-Fe-based alloy coating layer, an Sn coating layer on the upper layer of the two-layer Ni-Fe alloy coating layer, and a chromate-based processing layer on the uppermost layer. High performance Sn-based multi-layer plated steel sheet with excellent corrosion resistance, weldability and paint adhesion.