JPS60162756A - Steel sheet for can manufacture having superior corrosion resistance - Google Patents

Abstract

PURPOSE:To obtain a steel sheet for can manufacture having superior pitting corrosion resistance by regulating the relation between C and Cu in the specified composition of a steel sheet for can manufacture. CONSTITUTION:This steel sheet for can manufacture has a composition consisting of 0.0005-0.06% C, 0.01-0.09% Cu, 0.001-0.01% S, 0.1-0.5% Mn, 0.001- 0.020% P, 0.003-0.10% Al, 0.001-0.1% Cr and the balance Fe with inevitable impurities and satisfying an equation Cu%>=0.9C%-0.01. The steel sheet is characterized by the pitting corrosion resistance which is improved by increasing the Cu content in accordance with the equation when the C content is >=0.02%. By the composition, steel sheet for can manufacture having superior resistance to pitting corrosion by fish meat, etc. can be provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a steel plate for can manufacturing having excellent corrosion resistance.

Steel sheets for can manufacturing are used after being subjected to tin plating, electrolytic chromic acid treatment, nickel plating, etc. For tin-plated steel sheets,
When filled with contents such as acidic fruits, the base steel is protected against corrosion by tin 6ζ, and plain cans are generally used, but for many foods, the inner surface of the can is painted. Electrolytic chromic acid treated steel sheets are generally used after being painted. Although the steel base from the contents is protected from corrosion by a surface treatment film or painting, defects in the paint film or pinholes or cracks in the paint film are exposed due to processing such as lid making or drawing, and the metal base is exposed. On the other hand, when tin plating, electrolytic chromic acid treatment, or nickel plating is used for cans, the coating is thin and cannot completely protect the base steel, and when the above-mentioned coating defects occur, the steel base is often damaged. be exposed. When the exposed portion of the steel base is eroded by various contents, it eventually becomes a perforated can, and the can's original life of preserving the contents is lost. In the case of tin-plated steel sheets, when tin exhibits a more base potential than steel, the steel is protected from corrosion by tin, but pitting corrosion occurs in contents where the steel is more base than tin, such as fish cans. It becomes a perforated can. Various measures have been proposed to prevent perforation of carbonated beverage cans. For example, there is the special public Sho 4B-3051, which has a C<0.15
%1Mn: 0.20-1.00%, 84 <0.3
0%, Cu>0.1096-8: 0.020-0.
10096, ψ〉1, and 8b: 0.01 to 0.
2096-As: By containing a component of 0.01 to 0.2096, the corrosion resistance of carbonated beverage cans is improved. In recent years, the Cu content of steel sheets for cans has been reduced to 0.02.
Although the Cu content is 96 or less, it is said that corrosion resistance of steel is imparted by increasing the Cu content. Steel sheets for cans are subjected to electrolytic tin plating or electrolytic chromic acid treatment. Cu
If the content is 0.14 or more, defects in the surface treatment film, ie, bores, will be generated and the corrosion resistance will be reduced. Cuj
Addition of 0.1% or more of l improves the corrosion resistance of the steel itself, but it is unsuitable for use as a surface-treated steel sheet for cans. Therefore, for steel sheets for cans, it is necessary to suppress the amount of Cu added to 1.0% or less. Furthermore, although S is said to be an element that adds corrosion resistance to phosphoric acid-based contents, MnS is
MnS may exist as inclusions such as MnS, which acts as a starting point for pitting corrosion or promotes the propagation of pitting. , is a harmful element. Therefore, it is necessary to reduce the S content in order to improve the pitting corrosion resistance. Therefore, S is 0.02~
o, 1oo96, the pitting corrosion resistance to contents other than phosphoric acid-based products, such as fish meat containing citric acid-based or sulfur-containing amino acids, decreases.

The object of the present invention is to eliminate the above-mentioned defects and to provide a steel plate for can manufacturing having excellent pitting corrosion resistance.

That is, the present invention has C: 0.0005 to 0.065%
.

Cu: 0.01-0.09%-8: 0.001-0.
01%-Mn: 0.1-0.5%-P: 0.00
1-0.020%.

Al 0.003~0.10%, Cr:0.001~
0.1% and the relationship between C and Cu is Cu(96)≧0.90C96)-0.01, with the remainder consisting of k"e and inevitable impurities. Excellent corrosion resistance. This is a steel sheet for can manufacturing.

Next, the range of components constituting the present invention will be explained.

In order to improve pitting corrosion resistance, C needs to be 0.0696 or less, and since it is industrially difficult to reduce the C content extremely, a range of 0.0005 to 0.0696 is suitable. If the Cu content exceeds 0.09%, the electrodepositability (uniform electrodeposition) in tin plating or electrolytic chromic acid treatment will decrease, and the pitting corrosion resistance of surface-treated steel sheets for cans will decrease, so it should be 0.0996. must be kept to a minimum. Furthermore, Cu
If the content is less than 0.01%, the pitting corrosion resistance will not improve, so a range of 0.01 to 0.0996 is suitable.

Furthermore, if the S content exceeds 0.01%, MnS is generated and promotes pitting corrosion, so it must be kept below 0.01%.Also, the smaller the S content, the better the pitting corrosion resistance. , the current steelmaking technology has a limit of 0.0015i6, and lowering it is uneconomical due to increased manufacturing costs.

Therefore, the suitable content of 8 is 0.001 to 0, oi96.

Mn combines with S to form Mn8 and deteriorates corrosion resistance, so it must be kept at 0.5% or less, but a certain amount of M1 is required to prevent graphite precipitation on the annealed tempering plate. , 0.1 to 0.5% is preferred.

It is better to reduce P as much as possible for pitting corrosion resistance, but
0.001 to 0.0296 for economical reasons in steelmaking operations
limited to the range of

It is better to reduce M as much as possible from the viewpoint of pitting corrosion resistance, but in the case of M-killed steel, since it is used as a deoxidizer,
The range of At was limited to 0.003 to α1096.

Cr is necessary to prevent the precipitation of graphite generated during annealing. If graphite precipitates, various defects will occur in surface-treated steel sheets for can manufacturing, such as tin-plated steel sheets, and the corrosion resistance will deteriorate. , Cr content is 0.001
It is necessary to set it to 0.196.

Furthermore, the pitting corrosion resistance can be improved by satisfying the content of C and Cu of Cu(%)aO,9c(*)0.01.

As shown in FIG. 1, when the C content is 0.024 or more, the pitting corrosion resistance is improved by increasing the Cu content according to the formula: Cu≧α9C-0,01. 1st
The figure shows the relationship between CsCu content and pitting corrosion resistance. Aluminium-killed continuous casting steel containing various types of C and Cu was cold-rolled, annealed, and temper-rolled to yield 5.6 g/
After making a lid from a steel plate electroplated with nf tin and painted, it was filled with fish meat and stored at 38°C for one year. The pitting corrosion that occurred from the defective part of the paint film on the part where the lid was made was evaluated, and those where the pitting corrosion reached A or more of the plate thickness were marked as defective (x), and those that did not reach A were marked as good (○). did.

Figure 1+c shows tJ=U+c,Cu (!%)≧0.9C
Pitting corrosion resistance can be improved by satisfying (%) -0.01.

Next, the present invention will be specifically explained using examples.

Examples shown in Table 1? An aluminum killed continuous cast steel strip having the following composition was cold rolled to a thickness of 0.22mm, annealed and temper rolled, and then electrolytically tinned at 5.6 a/ai.

For Examples 1 to 7 and Comparative Examples 1 to 9, pitting corrosion resistance samples and thiocyanate tests were conducted as shown below.

(1) Pitting Corrosion Resistance Sample A 50 mg/dnf phenol-epoxy paint was applied onto the obtained tin-plated steel plate and heated at 210°C for 10 minutes. The obtained painted plate was processed into a lid, and fish meat (seasoned sardine was used) was filled into the can, and the sample lid was used to heat the can to a temperature of 38.
It was kept at 8°C and stored for 1 year. The depth of pitting corrosion that occurred from the defective part of the coating film in the lid manufacturing area was measured and evaluated.

(2) Thiocyanate porosity test The obtained tin-plated steel sheet was tested for porosity using the solution shown below, and the porosity of the tin-plated layer was evaluated by FeJil dissolved in the solution. and TCV (mg/dnf
).

As shown in Table 1, the composition of the solution is Rhodan ammonium 20g/Normal acetic acid 10Q/l Hydrogen peroxide 2096 (voJ!5%) 109/, the steel sheet for can making of the present invention has excellent pitting corrosion resistance. showed that.

[Brief explanation of the drawing]

The drawing shows C, Cujll in steel and pitting corrosion resistance.

Claims (1)

[Claims] C: 0.0005-0.06%-Cu: 0.01
~0.0948+0.001~0.01961Mn:
0. , 1-0.596-P: 0.001-0.020
%, Al: 0.003~0.1096°Cr:
0.001 to 0.196, and the relationship between C and Cu is Cu (%)≧0.9CC96>-0.01, with the balance consisting of Fe and inevitable impurities. Excellent corrosion resistance. steel plate for can manufacturing.