JPS60184687A - Manufacture of surface treated steel sheet for welded can - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of the titled steel sheet by plating a steel sheet subjected to annealing and temper rolling with nickel to a specified thickness, diffusing the nickel by heat treatment, carrying out tinning to a specified thickness, and melting the resulting tin layers by heating. CONSTITUTION:The surfaces of a steel sheet subjected to annealing and temper rolling are plated with nickel to 0.001-0.05mum thickness, and the steel sheet is heat treated in a nonoxidizing atmosphere to form diffusion layers of nickel on the surfaces of the steel sheet. Tinning is then carried out to 0.01-0.2mum thickness, and the resulting tin layers are melted by heating to manufacture a surface treated steel sheet for a welded can having improved corrosion resistance and suitability to coating. Chromium oxide films or chemically treated films each consisting of a metallic chromium layer and a chromium oxide layer may be formed on the tin layers by 5-20mg/m<2> (expressed in terms of metallic chromium) per one side so as to improve remarkably the corrosion resistance after coating.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a surface-treated steel sheet for welded cans that is inexpensive and has excellent corrosion resistance.

Among canning containers, so-called three-piece cans have traditionally been semi-111-bonded cans made of tinplate and adhesive cans made of tin-free steel (TF, S).
Since the development of a high-speed can body welding machine that uses copper wire as an electrode,
The use of so-called welded cans using this material is increasing. This requires the use of an expensive pure tin half-phase in the case of half-II+ bonded cans, and in order to ensure FIII wettability, the tin plating surface RMt is so-called #25 (2,
8 g/m' (pitch thickness: approx. 0.41 Lm); on the other hand, adhesive cans using TFS may break if the contents are subject to severe heat treatment conditions for sterilization. This is because there is a disadvantage.

Conventional #25 tinplate can be used as a surface-treated steel sheet for welded cans without any problems, but from the viewpoint of cost and resource conservation, if thinner R1 (=I tinplate) is used, there may be problems with deterioration of corrosion resistance. On the other hand, since TFS has a high electrical resistance in its plating layer and generates spatter during welding, it is impossible to apply it to welded cans.

JP-A No. 57-200592 discloses a technique previously disclosed as a method of improving the corrosion resistance of tinplate and producing an inexpensive surface-treated steel sheet for welded cans. In the disclosed technology, after nickel plating is applied to the surface of a steel plate,
A nickel diffusion layer is formed by heat treatment, this 1- is tin-plated, and then reflow treatment is performed.The coating rate formed on the steel sheet surface is high and the m-corrosion f'l is improved electrochemically. It is characterized by obtaining excellent corrosion resistance +1 due to the high density and homogeneity of the nickel diffusion layer and the iron-tin alloy layer formed thereon.

Tree inventors: 1. As a result of our efforts to further improve the corrosion resistance of surface-treated steel sheets for welded cans using the disclosed technology, we have made the following findings and have arrived at the present invention.

The above-mentioned disclosed technology is based on the premise that the heat diffusion treatment after nickel plating is also used as an annealing process as shown in the examples. Using +1'+ temper rolling to adjust according to purpose, nickel diffusion treatment (i.e. annealing) 21. It is necessary to do this after some time. The present inventors focused on the fact that if this temper rolling is performed after nickel plating and annealing diffusion treatment, the continuity of the nickel diffusion layer formed on the surface layer of the steel sheet will be impaired, and they have conducted annealing and conditioning in advance. It has been discovered that significantly superior corrosion resistance can be obtained by applying nickel plating and heat diffusion treatment to a steel plate that has been subjected to rough rolling, and then tin plating and reflow treatment, compared to the case using the disclosed technology. However, the present invention has been achieved.

That is, in the present invention, the steel plate is annealed and temper rolled in advance, and the surface of the steel plate is plated with nickel to a thickness of 0.001 to 0.05 lm, and then nickel is expanded on the surface of the steel plate by heat treatment in a non-oxidizing atmosphere. Surface treatment for welded cans 21) 1 Sugimata manufacturing method characterized by forming a layer, then applying tin plating of 0.01 to 0.2 gm, and further heat-melting the tin plating layer. It provides:

The present invention also includes: After rough annealing and temper rolling,
The surface of this steel plate is plated with 0.0'01 to 0.05 gm of nickel, and a nickel diffusion layer is formed on the surface of the valve plate by heat treatment in a Jli'l-forming atmosphere. Tin plating with a thickness of 0.2 μm is applied, and the tin plating layer is further heated and melted, and then one layer of the tin plating layer is coated with a tin plating layer of 5 to 2 μm on one side in terms of metal chromium.
The present invention provides a method for manufacturing a surface-treated steel sheet for welded cans, the feature of which is to form a chromium oxide layer of 0 mg/m' or a metal chromium layer and a chromium oxide layer.

The present invention will now be described in detail.

By heat treatment after nickel plating? lI
The first effect of the nickel diffusion layer is to increase the surface potential of the steel sheet to that of tin, thereby reducing the corrosion current at tin plating defects and improving corrosion resistance. As a second effect, the tin-iron alloy formed after tin plating and reflow treatment is made dense and uniform, thereby improving corrosion resistance. Due to these actions, tin plating (-1
Surface-treated steel sheet for welded cans exhibiting excellent corrosion resistance even with reduced borrowing strength is <11 t, but when the heat treatment for nickel diffusion is combined with the normal annealing process, the subsequent skin pass rolling The continuity of the nickel diffusion layer is lost in
The effect of improving corrosion resistance becomes smaller.

The present invention forms a defect-free and highly continuous nickel diffusion layer by performing nickel plating and heat diffusion treatment in a non-oxidizing atmosphere on a steel sheet that has been previously annealed and temper rolled. The main feature is that tin plating and reflow treatment are performed in one layer, and this provides corrosion resistance that is several orders of magnitude better than when temper rolling is performed after nickel plating diffusion treatment.

In the present invention, the reason why the thickness of the nickel plating applied to the steel sheet surface is limited to 0.001 to 0.05 gm is 0.0 gm.
Below 0.0L, the corrosion resistance effect due to change in steel plate surface potential after diffusion treatment and densification of the tin-iron alloy is not significant, and above 0.05pm, these effects are saturated.
This is because it is economically disadvantageous.

After nickel plating, the heat expansion treatment in a J1 oxidizing atmosphere 11r is carried out at a temperature of about 600'C or higher in the range of several seconds to several minutes, within a range where there is almost no deterioration of the material properties of the original plate. It is desirable that this be done.

The reason why the thickness of the tin plating performed after the nickel plating diffusion treatment is limited to less than 1 gm is 0.01 g.
If the thickness is less than 1.5 m, corrosion resistance will be insufficient even with a doped substrate treated with 2.0 nm diffusion treatment, and it will also be 0.0 m in terms of weldability.
．． 01μm or more1. is due to lack of ii). In addition, the tin plating thickness limit of 0.2 μm was abandoned because even if the plating thickness was increased beyond this point, the corrosion resistance effect would be saturated and the economic disadvantage would become significant. It is something.

The reason why the tin plating layer is heated and melted after tin plating is to form a dense iron-tin alloy layer at the boundary between the steel base and the plating layer, which is effective in improving corrosion resistance. This is because the tin oxide layer formed on the surface is insufficient to obtain the effect of improving paintability.

Providing a chromium oxide layer or a metallic chromium layer and a chromium oxide layer of 5 to 20 mg/rrf in terms of metallic chromium per side on the top layer of the surface-treated steel sheet for welded cans described below is a method of coating. It brings about a remarkable improvement effect in subsequent feeding. The limit of 5IIIg/m' for the chromium-attached area is determined from the viewpoint of improving corrosion resistance after painting, while the upper limit of 20m
This is because if g/rrf exceeds this value, a splatter phenomenon occurs during welding, and the steel sheet lacks suitability as a surface-treated steel sheet for welded cans. In addition, although there is a prior art such as Japanese Patent Publication No. 54-20940 that performs nickel plating and heat diffusion treatment as a base treatment for tin plating, it is characterized in that nickel plating and its heat diffusion treatment are performed again after temper rolling. The technology of the present invention is a completely new technology that differs in configuration from these prior art technologies.

In addition, what about nickel plating in the present invention? There is no need to specify any particular method for the irises tin plating method and the chemical treatment method for chromate-1-':9, and any conventionally known method may be employed.

Hereinafter, embodiments of the present invention will be described.

<Example 1> Aluminum quilt (continuously cast steel) was hot-rolled, pickled, and cooled for 111 tons.
After IE rolling, soaking strip 1680'CX 30 seconds of continuous annealing and 1.5% control γ'I rolling were applied to the pressure F-1, and the entire plated original plate A was prepared. 0 to the plating original plate. After applying nickel plating of Ol and M, heat expansion treatment was performed at 550°C for 30 seconds in an N2 + 10% H2 atmosphere. On the other hand, after cold rolling, 0.0
After 71 days of Nikel plating at 11trH, continuous annealing was performed under soaking conditions of 680°C for 30 seconds, heat treatment was performed at a tow ratio of 1.5%, and rolling was performed to obtain the plating original plate C. II.

Plating j5: 0.1 JLm of tin plating is applied to each of plates A, B, and C, and after heating and melting, 5 mg/lm per plate is applied.
nf metal chrome layer
A chemically treated skin consisting of a 5 mg chromium oxide layer was formed using the chromium oxide layer, and samples ID, E, and F were prepared.

For comparison, sample G was obtained by tin-plating plated original plate B and then subjecting it to the same chemical treatment without heat-melting treatment.

Table 1 shows the results of examining the corrosion resistance and weldability of samples DG, #25 tin, and TFS. Corrosion resistance is 0.1 weight of 40'0 after painting! The weldability was evaluated based on the time it takes for rust to occur after being immersed in an iI% citric acid aqueous solution.The welding speed was 5oIIllIllin, and the spatter per medium length was applied to the lower limit current value that would give a welding strength of I minutes. Evaluation was based on the number of occurrences.

Table 1 As shown in Table 1, the corrosion resistance of comparative sample F, which was temper-rolled after nickel diffusion treatment, is equivalent to or slightly inferior to that of conventional #25 tin, whereas inventive sample E has #25 tin. It exhibits significantly superior corrosion resistance compared to other materials. Comparative sample G, which was not subjected to reflow after tin plating, was inferior in corrosion resistance to sample E of the present invention. Note that there is no problem with weldability except for TFS.

<Example 2> After applying nickel plating of various thicknesses to the plated original plate A of Example 1 (that is, the one made by annealing and temper rolling),
A heating diffusion treatment of 50"C x 30 seconds was applied, followed by tin plating, reflow and chemical treatment similar to Example 1 to examine the effect on corrosion resistance. The corrosion resistance test method was the same as Example 1. be.

As shown in Figure 1, the nickel plating thickness is 0゜ootu.
■ A significant improvement in corrosion resistance can be obtained with the above, but 0.0
When the thickness exceeds 5 μm, the effect is almost saturated.

As shown in the εC52 table, the products made by the method of the present invention are excellent in both corrosion resistance and weldability.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the thickness of nickel plating and the time for occurrence of fraying. J vassal figure 1 nickel plate 1 OI)

Claims (2)

[Claims] (1) The surface of the steel plate is annealed and temper rolled in advance, and the surface of the steel plate is plated with nickel of O, 0 (jl-0, 051Lm).The surface of the copper plate is coated with nickel by heat treatment in a 1ma atmosphere. 4. Method D for producing a surface-treated steel sheet for welded cans, which comprises forming a diffusion layer, then applying tin plating of 0.01 to 0.2 gm, and then roughly heating and melting the tin plating layer. ,. (2) Rough annealing and tempering J (rolling and applying nickel plating of 0.001 to 0.05 μm on the surface of the steel sheet,) 1 heat treatment in an oxidizing atmosphere to coat the steel sheet surface with nickel. Avoid forming an expanding layer 1 then 0.01-
0.21Lmo') tin plating, further heat-melting the tin plating layer, and then
The layer contains 5 to 20 mg of metal chloride 17 per side.
A method for producing a surface-treated steel sheet for welded cans, which comprises forming a nf chromium oxide layer or a metallic chromium layer and a chromium oxide layer.