JPS60184688A - Surface treated steel sheet for welded can - Google Patents

Abstract

PURPOSE:To provide a titled steel sheet provided with both excellent adhesiveness of a coated film and weldability by forming a tin-iron-nickel ternary alloy layer on the surface of a steel sheet and forming island-shaped metallic tin on the top layer thereof. CONSTITUTION:The surface of a steel sheet is subjected to nickel plating as an embodiment and is then subjected to an annealing and diffusion treatment by heating and further to a melting treatment by heating so that a tin-iron-nickel ternary alloy layer and metallic tin having an island shape thereon are formed. The tin content in the ternary alloy layer is 0.05-1.0g/m<2> per surface in terms of metallic tin and the island-shaped metallic tin is 20-70% film area rate [expressed as A(%)]; further the content W(g/m<2>) of metallic tin is made to satisfy the equation W>=0.2XA/100. The surface treated steel sheet for welded cans which is excellent in both adhesiveness of a coated film and weldability is thus obtd. A chromic oxide layer or metallic chromium layer and chromic oxide layer are provided on the uppermost layer by a chemical treatment at 5-20mg/m<2> per side according to need.

Description

[Detailed description of the invention] The present invention relates to an inexpensive surface-treated steel sheet for welded cans.

Among canning containers, so-called three-piece cans include:
Traditionally, semi-bonded cans made of tinplate and 4B-2 cans made of tin-free steel (TFS) were the mainstream.
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 is expensive pure tin semi-r for semi-11J jointed cans.
#11 must be used, and in order to ensure half-11 wettability, tin-plated 1,11 coats must be coated with so-called #25 (2 coats per side).
．． 8 g/rrf'), and on the other hand, adhesive cans using TFS are disadvantageous for contents subject to severe heat treatment conditions for sterilization due to the risk of shell breakage. be.

For surface-treated steel sheets for welded cans, conventional #25 tin can be used without any problems, but if the amount of tin deposited is reduced from the viewpoint of cost and resource conservation, the edibility and weldability will deteriorate. It becomes a problem.

The present inventors repeatedly investigated the relationship between the structure of tin plating, corrosion resistance, and weldability in ultra-thin tin plating, and found that when the plating surface is made of a tin-iron-nickel ternary alloy,
High density and coating density of ternary alloy layer 71 Tendency 1-
We found that although the corrosion resistance was significantly improved due to the effect, the weldability deteriorated.On the other hand, when the surface was made of metallic tin, the weldability was good, but the corrosion resistance after painting was poor. - Partial gold Jm on 1- of the iron-nickel ternary alloy layer
A surface-treated steel sheet for welded cans of the present invention in which tin is present has been developed.

In other words, the present invention contains tin in the alloy on the surface of the steel plate! - is gold rdS tin exchange 9, 0.05-1.0 g/rn per side
'cD has a tin-iron-nickel ternary alloy layer, and the metal tin present in the upper layer has a va area coverage (expressed as A (%)) 20 ~
70% island shape II! and A (%) and metal tin part W (g/m').

The present invention provides a surface-treated steel sheet for welded cans, which satisfies the following relationship: W2O,2x-Am 00 .

The present invention also provides a tin-iron-nickel ternary alloy layer having a tin content of 0.05 to 1.0 gem' per side in terms of metal tin on the surface of the steel plate, and the metal present in the upper layer. Tin exhibits an island shape with a coverage area ratio (expressed as A (%)) of 20 to 70%, and the relationship between A (%) and metal tin hIW (g/m'') is W2O 2 x Ding. 4, furthermore, the top layer has a chromium oxide layer or a metal chromium layer and a chromium oxide layer of 5 to 20 + wg/rn' per side in terms of metal chromium.
The present invention provides a surface-treated steel sheet for welded cans having the following characteristics.

The present invention will be explained in more detail below.

As mentioned above, when a tin-iron-nickel ternary alloy layer is formed on the surface of a steel sheet, the corrosion resistance is improved by the dense ternary alloy layer itself, and the corrosion resistance is improved by improving the adhesion of the coating film. Even if the amount of plating (=I) is reduced, extremely good corrosion resistance can be achieved by 1!t. However, ternary alloys have relatively high hardness, so they have poor electrical conductivity and cause spatter phenomenon during seam welding. cause.

- When the plating surface is completely made of metallic tin, the weldability is good, but the coating film adhesion is poor, so the corrosion resistance after coating is not 1.min.

The surface-treated steel sheet for welded cans of the present invention has tin-iron-nickel three
By partially forming island-like metal tin on the top of the original alloy layer, the ternary alloy layer provides excellent coating I+! ,! Adhesion and gold I+! Its greatest feature is that it combines the appearance of excellent weldability with tin.

The quality of corrosion resistance after painting is largely influenced by the thickness of the tin-iron-nickel ternary alloy layer (4-I), and the tin content in the alloy (IL = 0.05 g/m per side in terms of metallic tin).
If it is less than , the film defects will increase and the food quality will deteriorate by 1, so this is set as the lower limit.

- On the other hand, if the J-registered tin content exceeds 1.0 g/rn', the effect will be saturated and the economic disadvantage will become large, so this is set as the 2nd limit.

Good post-painting corrosion resistance due to the paint film adhesion effect of the ternary alloy layer is lost when the coverage area ratio of island-shaped metallic tin exceeds 70%, so 70% of the area covered by metallic tin is shall be.

The metallic tin formed in an island shape on the ternary alloy layer increases electrical conductivity by deforming itself during welding, thereby improving weldability, but when the coverage area ratio is less than 20%, The effect of improving weldability due to the above action is lost. Therefore, the coverage area ratio of the island-shaped metal tin needs to be 20% or more.

Furthermore, the amount of metallic tin W (g/G) required to ensure weldability, that is, to obtain sufficient welding strength at the limit current for spatter generation, is □ W2O,2× -Am OO (where A is the coverage area ratio of metallic tin ( %)) It is necessary to satisfy the following relationship. That is, when W is smaller than 0.2 x 2 o, spatter is unavoidable in order to obtain sufficient welding strength.
The larger the value compared to A-1, the wider the difference between the 00 spatter generation limit current and the welding current required to obtain sufficient welding strength, that is, the range of appropriate welding current. Since widening the current range is economically disadvantageous, the upper limit for practical use is W=2. Ij can be obtained by OX -N- 00.

The amount of metal tin W and gold 1ull required to obtain good weldability
The fact that the tin coverage area A has the above relationship is interpreted as follows.

In other words, from W≧0.2×d■1, 10 second WX A≧0.2 (constant) left side, WX
ioo is a value corresponding to the local metallic tin in the island 1-metallic tin region, and the fact that this is a constant planting period means that the height of the island-shaped metallic tin mountain is I can hear and taste that it is 1-. As already mentioned, the improvement in weldability due to metallic tin is due to the fact that the metallic tin itself is deformed by the electrode pressure F and increases the energization P1, and the height of the islands of metallic tin is above a certain value] The relationship that good weldability can be obtained is easily understood if it is 2.

As the top layer of the above-mentioned surface-treated steel sheet for welded cans, 5 to 20 mg/Tn per side in terms of metallic chromium is added.
Providing a chromium oxide layer or a metal chromium layer and a chromium oxide layer has a significant effect in further improving post-painting corrosion resistance. The lower limit of the amount of chromium (5 g/rf) is a value where the above-mentioned effects become evident, while if it exceeds the upper limit of 2 (lag/rrf), weldability deteriorates.

In addition, the surface-treated steel sheet for welded cans as described in 1.
1) Although the method for producing is not particularly limited, the following method may be mentioned as one of the easiest manufacturing methods.

Nickel plating is performed on the surface of the copper plate, which is then subjected to heat diffusion treatment that also serves as annealing, and then electroplated with tin, followed by glue flow treatment at an appropriate temperature (for example, line speed 250) without applying flux. m/+
Apply a voltage of about 140V at min. )I do. As a result, an uninvented surface-treated steel sheet for welded cans having a uniformly formed tin-iron-nickel alloy layer and metallic tin having island shapes formed on the I- layer is obtained.

Examples of other manufacturing methods include nickel plating and tin plating, followed by complete alloying by heating in a non-oxidizing atmosphere to form a ternary tin-iron-nickel alloy layer, followed by cooling. In step 1, there is also a method of forming island-shaped metallic tin by blowing fine powder of metallic tin at a temperature of tin melting point I:.

Furthermore, there is no particular restriction on the method of chromium-based chemical treatment applied to the tin layer 1-, and iT! Kuro 1-r
Any conventionally known force D may be used, such as a method using a dirty sorter, a method using a chlorine-acid treatment bath, and the like.

The embodiments of the present invention will be described above.

<Example 1> 0.05 to 0.2 g per moon surface on the steel plate surface after cold rolling
Nickel plating of m' was applied, and heat diffusion treatment including annealing was performed under soaking conditions of 670° C. for 40 seconds. After temper rolling, tin plating of 0.02 to 2.0 g/m'' was carried out, followed by reflow treatment under various conditions, followed by 30 g/m of chromic acid and 0.3 g/m of sulfuric acid in ice-water solution. Metal chromium 5 mg/m', chromium oxide 7
A chemical treatment of 11 g/m' was applied.

The obtained plated steel plate and #25 tin plate (tin plated 71'
, 9t, 2.8 g/m'), e, l O tinplate (1.-1 g/rrf) was examined for corrosion resistance and weldability after painting. Table 1 shows the results. In addition, the corrosion resistance was evaluated by immersing it in a Q, 1 rrc aqueous citric acid aqueous solution at 40°C after painting, and measuring the time until rust appeared. The weldability was determined by the Jf value in terms of the number of spatters generated per unit length at a welding speed of 1 and 50 m/win and at the lower limit flow value at which sufficient welding strength could be obtained. The metallic tin coverage A (%) was determined by observation using an electron microscope.

As shown in Table 1, the surface-treated steel sheet for welded cans of the present invention exhibits corrosion resistance and weldability equivalent to or better than #25 tinplate with a small amount of tin deposited.

Table 1 fI) The t-line part is the same as that of the present invention box 171 (Example 2) Example 1.
A plated plate with a metal tin density of 5 g/m', 35 g/m' and a metal tin coverage area of 50% was obtained, and this was subjected to chemical stress (chromate treatment) of various JM amounts to improve corrosion resistance and welding. We investigated the effects on sexuality. The weldability was evaluated using the same method as in Example 1, but the corrosion resistance was evaluated using a citric acid concentration of 0.
The test was carried out under the conditions of 5g/'41 and a temperature of 50°C.

As shown in Table 2, those that are outside the scope of the present invention are inferior to non-invented products in either corrosion resistance or weldability.

Claims (2)

[Claims] (1) On the surface of the steel plate, there is a tin-iron-nickel ternary alloy layer with a tin content of 0.05 to 1.0 g/rn' per 11 surfaces in terms of metal tin conversion, -1 Number 11 is an island shape in which the metallic tin existing in one layer has a coverage area ratio (expressed as A (%)) of 20 to 70%, and A (%) and the amount of metallic tin W (g/m') are W2O, A surface-treated steel sheet for welded cans, characterized in that it satisfies the relationship: 2×-Am 00 . (2) On the surface of the steel plate, the tin-containing t1 in the alloy has a tin-iron ternary alloy layer of 0.05-1.0 g/m' per 11 surfaces in terms of metal tin; Let ψ- be an island shape where gold 1f tin existing in one layer covers 20 to 70% of the area -44 (expressed as A (%)), and A (%) and metal tin W (g/m')
It satisfies the following relationship: W2O, 2 x D 1, and further has a chromium oxide layer or a metal chromium layer and a chromium oxide layer with an amount of 5 to 20 mg/rn' per side in terms of metal chromium. Characteristic surface-treated steel sheets for welded cans.