JPH0324282A - Production of steel sheet plated with chromium - Google Patents

Abstract

PURPOSE:To develop steel sheets having a plated chromium layer which are excellent in specular properties, corrosion resistance and workability by heating stainless steel sheet or cold-rolled steel sheet in the hydrogen atmosphere and thereafter forming the plated film of specified metal by a vacuum deposition method and successively plating chromium thereon. CONSTITUTION:Stainless steel sheet or cold-rolled steel sheet is heated at 400-1000 deg.C for 1-10 minutes in the hydrogen atmosphere to remove passive film and oxidative film on the surface. Thereafter Co, Ni, Mo and Nb, etc., are deposited by evaporation in 0.1-5.0mum thickness on the surface thereof by a vacuum deposition device. The vapor deposited films of these metals are formed and also the alloy layer of both metals is formed in the interface of the vapor deposited film of these metals and the steel sheet material to be plated. Then chromium is plated in 0.1-5.0mum thickness on the plated metallic layer due to vapor deposition by an electroplating method. Thereafter steel sheet plated by chromium which is excellent in specular properties, corrosion resistance and workability is wound in a coil shape.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing chrome-plated steel sheets, and more particularly, to a method for manufacturing chrome-plated stainless steel sheets and cold-rolled steel sheets with excellent specularity, corrosion resistance, and workability. How to say it,
The present invention relates to a chromium-plated stainless steel sheet and an ordinary cold-rolled steel sheet coil manufactured by the manufacturing method.

Conventional technology Conventionally, when applying chrome plating to stainless steel sheets and ordinary cold-rolled steel sheets, there is a passive film on the surface of the stainless steel sheet and an oxide film on the surface of the ordinary cold-rolled steel sheet. When plating is applied, the attached plating layer tends to peel off, so strong degreasing, etching, etc. are performed as pre-treatment before plating.
Films such as passive films and oxide films are removed in advance.

Then, before chromium plating, a suitable metal such as cobalt is plated, and then chromium is plated, thereby producing chrome-plated stainless steel sheets and ordinary cold-rolled steel sheets.

In addition, the above-mentioned cobalt → chrome plating process is divided into a post-plating method, which is applied after processing the stainless steel plate into the desired shape, and a pre-plating method, which is applied before processing the stainless steel plate into the desired shape.
This is done using two methods: a pre-plating method and a pre-plating method.

Problems to be Solved by the Present Invention As mentioned above, when applying chromium plating to stainless steel sheets and ordinary cold rolled steel sheets, unless the passive film or oxide film on the surface layer of these steel sheets is removed by pre-treatment such as etching, the plating will be difficult. For example, when pre-plating a stainless steel plate, if a passive film remains, the chrome plating layer will easily peel off due to slight bending of the steel plate, causing problems in workability. arise.

On the other hand, conventionally, small amounts of molybdenum, titanium, niobium, and nitrogen have been added to stainless steel sheet materials such as SUS304 series and SUS430 series to improve corrosion resistance, but films such as oxide films or passive films have been added. If you try to completely remove it using conventional methods such as etching, there is a problem that the corrosion resistance will be impaired, and the corrosion resistance will be lower than that of the material before plating.

As mentioned above, if conventional methods were used to completely remove films such as oxide films or passive films in order to improve the adhesion of the plating layer, corrosion resistance would be completely lost; If it remains, it will have an adverse effect on the adhesion of the plating layer, making it impossible to obtain a uniform mirror finish on the final chrome-plated surface.

In addition, in the manufacturing process of stainless steel sheets, the final finish (B-A finish) is performed after bright annealing, but in this process, due to errors in the temperature distribution of the annealing furnace, gas atmosphere, etc., the surface of the steel sheet may The thickness of the formed passive film differs in the width and length directions of the steel plate. Therefore, even if the working conditions of the plating process, the conditions of pickling, electrolysis, etc. are kept constant, it is difficult to uniformly remove the passive film from each part of the steel plate.

Means for Solving the Problems The present inventor conducted various studies in order to solve the above-mentioned problem of the passive film and develop chrome-plated stainless steel sheets and ordinary cold-rolled steel sheets with excellent corrosion resistance, specularity, and workability. I did it. As a result, by heating the steel plate at high temperature in a hydrogen atmosphere in a vacuum container, the passive film and oxide film are removed and the steel plate is heat treated, and then an appropriate metal is deposited on the steel plate. , an alloy layer that is metallurgically bonded to the interface between the steel sheet base and the metal is formed, and the alloy layer is formed without pretreatment such as ethoching, which is conventionally used for films such as Fudocho film. discovered a method of firmly bonding the vapor-deposited metal plating layer and the steel sheet base to improve corrosion resistance and adhesion of the plating layer.

Therefore, the present invention is characterized in that after a steel plate to be plated is heated at a high temperature, an appropriate metal is vapor-deposited using a vacuum coating method such as a vacuum evaporation method, and then chrome plating is applied to an appropriate thickness. The present invention provides a method for manufacturing chromium-plated steel sheets.

Specifically, chrome plating is characterized in that a stainless steel plate or an ordinary cold-rolled steel plate is used as the steel plate to be plated, and cobalt, nickel, molybdenum, triobium, etc. are used as the metal to be vacuum evaporated. It provides steel plates.

More specifically, after heating a stainless steel plate and an ordinary cold-rolled steel plate at 400°C to 1000°C for 0.1 to 10 minutes, a suitable metal such as cobalt, nickel, molybdenum, niobium, etc. is vapor-deposited to a thickness of 0.1 to 5.0μ to form an alloy layer of the steel sheet material and vapor-deposited metal within 5μ at the interface between the steel plate and the above-mentioned vapor-deposited metal plating layer, and then, on the above-mentioned alloy layer. Then, by electrolytic plating method etc., 0.
The present invention provides a method for producing a chromium-plated steel sheet that is plated with 1 to 5.0 μm of chrome and has excellent uniform specularity, adhesion, and corrosion resistance.

The present invention also provides a chromium-plated steel coil, which is characterized in that the chrome-plated steel sheet produced by the method described above is wound into a coil.

By using the above-described method for manufacturing chrome-plated steel sheets, there is no need for pre-treatment such as etching to remove films such as passive films on the surface of stainless steel W4 sheets and ordinary cold-rolled steel sheets, and Instead of removing the passive film and oxide film that improve corrosion resistance, an alloy layer is formed between the steel sheet material and the deposited metal, and the formation of the alloy layer compensates for the corrosion resistance and improves the corrosion resistance of the alloy layer. The degree of adhesion of the vapor-deposited plating layer formed on the surface is improved. Therefore, the specularity of the chromium plating layer can be improved, and the workability of chromium-plated stainless steel sheets and ordinary cold-rolled steel sheets can be improved.

Hereinafter, the present invention will be explained in detail with reference to embodiments shown in the drawings.

Figure 1 shows the equipment for the first stage vapor deposition plating process on a plated object made of stainless steel plate or ordinary cold rolled steel plate, and Figure 2 shows the equipment for the second stage chrome plating process after the above vapor deposition plating. This figure schematically shows an electrolytic plating apparatus.

In Figure 1, l is a vacuum vessel for vapor deposition, 2 is a vacuum vessel for heating,
3 is a vacuum vessel for unwinding a coiled steel plate, and 4 is a vacuum vessel for winding up a coiled steel plate. The unwinding vacuum container 3 communicates with the heating vacuum container 2 via a vacuum passage 9. The heating vacuum container 2 is connected to the vapor deposition vacuum container 1 via a vacuum passage 5.
The vapor deposition vacuum vessel l communicates with a cooling vacuum vessel 7 via a vacuum passage 6. Furthermore, the cooling vacuum container 7 is in communication with the winding vacuum container 4 via a vacuum passage 8 .

The unwinding vacuum container 3 is formed in a size sufficient to accommodate a coiled stainless steel sheet and an ordinary cold rolled steel sheet 11 wound around a roll 10.
A guide roller l2 is installed to guide the coiled steel plate 11 into the vacuum passage 9 and unwind it, and a mechanism (not shown) for continuously feeding out the steel plate 11a by rotating the coiled steel plate 11 in the direction of the arrow is installed. We are prepared.

The heating vacuum volume 'iA2 is provided with guide rollers I3a, l. which guide the steel plate 11a in pairs from above and below, respectively. 3b,
and 13c, 13d are arranged, and an electron beam generator l4 for heating the steel plate is provided on the outer wall surface, and a hydrogen supply device (not shown) for supplying hydrogen into the heating vacuum container 2 is connected, The interior of the heating vacuum container 2 is a hydrogen atmosphere.

The vacuum vessel l for vapor deposition has a guide roller I6 for guiding a steel plate installed near the intake port 15a communicating with the vacuum passage 5,
Following the guide roller l6, guides 17a, 17bSl7c1 bend and guide the steel plate to the outlet 15b.
17d are arranged sequentially. The number and size of the rollers are changed as appropriate depending on the size of the vapor deposition container.

Furthermore, inside the vacuum vessel I for vapor deposition, a metal 18 to be vapor deposited is provided.
Containers 19aS+9b, such as crucibles, containing the metals 19aS and 9b are placed at appropriate intervals, and electron beam generators 20a and 20bh emit electron beams to melt the metal l8 in these containers. It is installed on the outer wall of 1. Metal 18 melted by these electron beams
is evaporated in vacuum in the vapor deposition vacuum vessel l, and is deposited as a uniform film on the entire surface of the steel plate 1lb guided by the guide rollers 17a = 17d, and the steel plate 1lb passes through the vacuum vessel. The thickness of the film can be adjusted arbitrarily depending on the time (residence time).

The above vacuum container for vapor deposition! A guide roller/cooling roller 2l is installed in the cooling vacuum container 7, which communicates with the outlet 15b of the vacuum chamber 7 via the vacuum passage 6, and is used to roll the steel plate taken out from the vapor deposition vacuum container l into a coil shape. The temperature is lowered to a certain temperature. As the structure of the cooling roller, a known structure can be used, for example, a structure in which a passage for cooling air is provided inside the roller may be used.

The winding vacuum vessel 4, which communicates with the cooling vacuum vessel 7 via the vacuum passage 8, is equipped with a roller 10° for winding up the steel plate conveyed therein.
A rotating mechanism (not shown) is installed that rotates the steel plate in the direction of the arrow and winds the steel plate into a coil.

Fig. 2 shows an electrolytic plating apparatus for applying chromium plating to a stainless steel plate or ordinary cold rolled steel plate which has been subjected to vapor deposition plating using the apparatus shown in Fig. 1. In the figure, 31 is an electrolytic plating apparatus, 32 is a water washing apparatus, and 33 is an electrolytic plating apparatus. are drying devices, 35a to 35d
is the guide a-ra.

The electrolytic plating apparatus shown in FIG. 2 is continuously supplied with a coil 10'' of steel sheets that have been subjected to the vapor deposition plating process shown in FIG. It is manufactured by winding a plated ordinary cold-rolled steel plate into a coil 34.

Next, the operation of the above-described device according to the present invention will be explained.

A 1L coiled steel plate made of a stainless steel plate, an ordinary cold-rolled steel plate, or the like is attached to an unwinding vacuum vessel 3, and a heating vacuum vessel 2 in which an appropriate hydrogen atmosphere is maintained.
Continuously convey to. In the heating vacuum container 2, the steel plate is heated by the electron beam of the electron beam generator 14 until it reaches an appropriate temperature. For example, in the case of the above-mentioned stainless steel plate and ordinary cold rolled steel plate, the temperature is 400°C to 1000°C for 0.1 minute. ~
Heat for 10 minutes.

By being heated at the above-mentioned high temperature in a hydrogen atmosphere in the heating vacuum container 2, inter-corrosion corrosion occurs in the steel plate material, and the saw carbon solid-solved in the base material forms a passive film on the surface. It combines with chromium to become chromium carbide and continuously precipitates at grain boundaries. Along with this precipitation action, the amount of chromium, which is the main component of the passive film, decreases, and the passive film is finally removed. In this way, the passive film and the oxide film are removed by heating in the heating vacuum container 2, and at the same time, the steel sheet is heated as a pre-evaporation treatment.

The heat-treated steel plate is further continuously conveyed to the vacuum chamber I for vapor deposition via the vacuum passage 5. In the vacuum vessel 1 for vapor deposition, metal 18 such as cobalt placed in the vessels 19a and 19b is melted by the electron beam of the electron beam generators 20a and 20b, and the steel plate is placed in the vacuum vessel 1 for vapor deposition through the outlet 15b. It is plated to an appropriate thickness before being released. For example, when cobalt is vapor-deposited on the stainless steel plate or ordinary cold-rolled steel plate, it is plated to a thickness of 0.1 to 5.0 μm.

The steel plate 11c sent out from the outlet +5b of the above-mentioned vapor deposition vacuum container l is cooled in the cooling vacuum container 7, and then transferred to the roller 1 in the winding vacuum container 4 via the vacuum passage 8.
It is wound up at 0°.

Since the metal deposited by the above method is deposited in a vacuum and at high temperatures, it diffuses into the stainless steel sheet or ordinary cold-rolled steel sheet material, forming an alloy with an appropriate thickness (5μ or less) on the surface layer of the steel sheet material. The layers take shape.

Since the alloy layer is firmly bonded to the steel plate base, it is possible to improve the adhesion between the steel plate base and the plating layer.

A coil 10'' wound with a steel plate coated with vapor deposition using the above method is conveyed to the electrolytic plating apparatus shown in FIG. 2, guided by guide rollers 35a, and continuously conveyed to the electrolytic plating apparatus 3l. reactor.

The vapor-deposited plated steel plate is then chromium plated by an electrolytic plating method in the electrolytic plating apparatus 3l.

In the case of the above-mentioned stainless steel plate or ordinary cold-rolled steel plate coated with cobalt, 0.1 to 5.0
Apply chrome plating to a thickness of μ. The above chrome plating is formed on the second layer of the cobalt alloy layer, so it has a high degree of adhesion to the base steel plate.

The electrolytic plating method mentioned above is the electrolytic plating method previously provided by the applicant of the present application (Patent Application No. 200G9, No. 631).
is suitable. In other words, in the electrolytic plating method, when the steel plate is moved through the plating tank, the plating solution is forced to flow almost perpendicularly, and the plating process is performed at a high current density, so that the entire surface of the steel plate is uniformly coated. Plating is given by thickness. However, it goes without saying that the method is not limited to this chrome plating method.

The steel plate after chromium plating is continuously transported to a washing device 32 and washed with water, and further transported to a drying device 33 and dried. After drying, the steel plate is wound around a winding coil 34 equipped with a winding mechanism (not shown).

The above combination of vapor deposition plating and electrolytic plating is to electrolytically plate chromium after the above cobalt vapor deposition plating (
Combinations of nickel-chromium, molybdenum-chromium, and niobium-chromium are desirable, as is cobalt-chromium.

<<Experimental Example>> In order to compare and examine the corrosion resistance of the chromium-plated steel sheet manufactured by the method for manufacturing a chromium-plated steel sheet according to the present invention with a conventional example, a corrosion resistance test was conducted under the following conditions.

Stainless steel j1 as a sample (material)! (SUS430,
Three types of steel plates were used: SUS304) and ordinary steel plate (SPC G). Further, the following three conditions were provided for each of the above samples.

・Sample condition A: The sample was not subjected to any plating treatment. ・Sample condition B: The sample was coated with cobalt plating using the electrolytic plating method with the film thickness shown in Table 1, and then chromium plating was applied to the sample. When using the conventional plating method - Sample condition C: The plating method according to the present invention was applied to the sample under the conditions shown in Table 2. After heating the sample, cobalt was deposited and plated to form an alloy layer. It is electrolytically plated with chromium.

The test method is to apply JIS22371 to each sample.
Corrosion resistance was investigated by conducting a salt spray test similar to the above.

Regarding the above test, based on rating No. 8, S
Table 3 below shows the results of measuring the time required for white rust to occur on US430 and SUS304 and the time required for red rust to occur on SPCC.

As shown in Table 3, when sample conditions A and B and sample condition C are compared when SUS430%SUS304 is used as a sample, the time until white rust appears under sample condition C is longer than that under sample condition A for both samples. It is significantly longer than those of cases B and B, approximately 2.5 to 3 times longer. The same is true for stainless steel when SPCC is used as a sample.
The time until red rust occurs for sample condition C is the same as that for sample conditions A and B.
It is significantly longer than that for sample condition B, and is approximately 2.5 to 3 times longer than that for sample condition B.

From the above, it can be concluded that the steel sheet manufactured by the method for manufacturing a chromium-plated steel sheet according to the present invention has about 2.5 to 3 times higher corrosion resistance than the steel sheet that has been subjected to cobalt plating and chrome plating using conventional electrolytic plating. has been proven.

(Left below) Effects of the Invention As is clear from the above explanation, according to the method for producing a chromium-plated steel sheet according to the present invention, an M plate such as a stainless steel plate or an ordinary cold-rolled steel plate is coated with cobalt, etc. after being heated at a high temperature. Since chrome-plated stainless steel sheets and chrome agate cold-rolled steel sheets are produced by vapor-depositing metals in a vacuum and then depositing chromium by electrolytic plating, they have the following effects.

■Since an alloy layer is formed in which the metal and the steel plate base are strongly bonded at the interface between the temporary base and the vapor-deposited metal plating layer, the steel plate base, the vapor-deposited metal plating layer, and the post-plated chrome plating layer The degree of adhesion can be improved. Therefore, no bin poles occur and the specularity is improved. Moreover, even during processing performed after plating, the plating does not peel off, and workability can be improved.

(2) Corrosion resistance can be improved because it eliminates the need to remove films such as passive films through pretreatment such as etching, which was required in the past. For example, SUS304,
Cobalt is vacuum-deposited on a stainless steel plate such as SUS430 using the above method, and then chromium is attached by electrolytic plating.The steel plate is made by adding molybdenum, titanium, niobium, nitrogen, etc. to SUS304 or SUS430, or by conventional methods. It is 2.5 to 3 times more corrosion resistant than plated materials.

(2) The alloy layer formed between the steel sheet material and the vapor-deposited metal plating layer is softened and has more extensibility than when metal plating is applied to the steel sheet by conventional methods such as electrolytic plating. Therefore, the workability of the chrome-plated steel sheet can be improved.

■Since pre-treatments such as degreasing and etching to remove passive films, which were previously required, are no longer necessary, the ζ manufacturing process is simplified, productivity is improved, and costs are reduced. I can do it.

[Brief explanation of drawings]

FIG. 1 is a schematic view showing an example of a vapor deposition apparatus for a vapor deposition method according to the present invention, and FIG. 2 is a schematic view showing an example of an electrolytic plating method for an electrolytic plating method according to the present invention. 1... Vacuum container for vapor deposition, 2... Vacuum container for heating, 3... Vacuum container for unwinding, 4... Vacuum container for winding, 5, 6, 8, 9... Vacuum passage , 7... Vacuum vessel for cooling, IO, 10... Roller, II... Steel plate, 14... Electron beam for heating steel plate, 19... Container 20... Electron beam for metal melting, 31 ...Electrolytic plating device, 32...Water washing device, 33...Drying device, 34...Coil,

Claims (4)

[Claims] 1. After heating a steel plate to be plated at a high temperature, a suitable metal is vapor-deposited and plated using a vacuum film forming method such as a vacuum evaporation method to form an alloy layer of the metal and the steel plate on the surface of the steel plate, and then chromium is applied. A method for manufacturing a chrome-plated steel sheet, characterized by applying plating to an appropriate thickness. 2. The production of a chromium-plated steel sheet according to claim 1, characterized in that the steel sheet to be plated is a stainless steel sheet or an ordinary cold-rolled steel sheet, and the metal to be plated by vacuum evaporation is cobalt, nickel, molybdenum, niobium, etc. Method. 3. Stainless steel plates and ordinary cold rolled steel plates are heated to 400℃~
After heating at 1000℃ for 0.1 to 10 minutes, cobalt, nickel, molybdenum,
A suitable metal such as niobium is vapor-deposited to a thickness of 0.1 to 5.0 μm, and a 5 μm layer is applied to the interface between the steel plate and the vapor-deposited metal plating layer.
Form an alloy layer of the steel plate material and the vapor-deposited metal within 0.1 to 5.
．． A method for producing chrome-plated stainless steel sheets and ordinary cold-rolled steel sheets with excellent specularity and corrosion resistance by applying 0μ chrome plating. 4. A chromium-plated steel plate coil, characterized in that the steel plate manufactured by the method according to claim 1, 2 or 3 is wound into a coil shape.