JPS6059075A - Steel sheet for enameling capable of eliminating pretreatment stage before enameling - Google Patents

Abstract

PURPOSE:To make pretreatment stages before enameling unnecessary by forming composite plating consisting of Ni and Co on the surface of a cold rolled steel sheet by a specified amount. CONSTITUTION:Composite plating consisting of Ni and Co is formed on the surface of a cold rolled steel sheet by 0.01-1.5g/m<2> before recrystallization annealing. The amount of Co in the plating is adjusted to >=0.002g/m<2>. The composite plating is homogenized by recrystallization annealing, and part of it is diffused in the surface layer of the steel sheet. By this method, pretreatment stages before enameling such as degreasing, pickling, Ni dipping and neutralization can be eliminated.

Description

Detailed Description of the Invention The technical field relates to cold-rolled steel sheets for enameling, which have extremely excellent adhesion after firing and can omit pretreatment in the enamel glazing process. The technical content described here relates to the plating of cold-rolled steel sheets, particularly the improvement of enamel adhesion through surface treatment with Ni and Co composite plating, and is located in the field of technology to which steel sheets for glazing belong.

BACKGROUND TECHNOLOGY Usually, the manufacturing process for Uro products is as shown in Figure 1(a).After pressing, pretreatments such as degreasing, pickling, N1 dip, and neutralization are performed, and after drying, glazing and firing are performed. Is going.

However, these methods involve a large number of steps, resulting in high costs, and although they require a lot of effort, they do not reduce the number of creeping defects. Furthermore, the use of acids causes pollution problems such as deterioration of the environment and disposal of waste acids, and there are various problems such as the need for a large amount of equipment and cost to deal with these problems.

In general, pre-treatments such as pickling and Ni dip treatment mentioned above were considered indispensable to improve the adhesion of enamel, but pickling and N1
As a way to omit the dipping process, unfired steel plates (
(Refer to Japanese Publication No. 48-29289) was proposed, but in this method, the steel sheet manufacturer goes through a hot rolling stage, then glazes, dries, and then cold-rolls, so it requires special equipment and materials. In particular, in the enamel film after firing, unnecessary resin is mixed into the glaze, which increases costs, and another drawback is that black smoke is generated due to the decomposition of the resin during the firing stage, causing air pollution. There is also.

Separately, a steel plate for enameling that can omit pickling and N1 dipping is disclosed in Japanese Patent Publication No. 1835-1835, and according to the disclosure, recrystallization annealing concentrates Mn on the surface of the steel plate and improves the adhesion of the enamel. To inhibit Mn, 0.
50% or less, and by making the steel plate surface clean and activated by cold rolling, that is, making it highly reactive,
It improves adhesion and enables enameling as cold rolled, but it cannot be used for applications that require workability.
It is only suitable for unprocessed enamel blackboards.

Furthermore, a steel plate for enameling which is subjected to N1 plating after recrystallization annealing and which eliminates the need for pre-treatment after press working is also disclosed in Japanese Patent Publication No. 47-4476, but in this case N1
Pressing after plating requires the formation of a protective film after N1 plating to prevent the plating from separating and reducing the adhesion of that part, which inevitably increases costs. The peeled parts will leave defects such as being susceptible to rust.

In any case, in normal enamel firing, multiple firings are performed, such as undercoating and one finishing layer, and multiple firings are also performed to repair defects in the enamel.

When firing many times in this way, the adhesion of the enamel rapidly deteriorates, but no optical countermeasures have yet been developed for this problem.

OBJECT OF THE INVENTION To solve the above-mentioned problems, the adhesion of enamel is extremely good even after firing a large number of times.
It is an object of the present invention to provide a steel plate for enameling that can omit pre-treatment such as N-editing.

The inventors first applied N1 plating of 0.19/m2 to Z O/l/, z to the surface of the steel sheet after cold rolling and before annealing the steel sheet, regardless of the number of firings. , it was discovered that the rapid decline in enamel adhesion can be avoided, but the present invention goes further and shows that by composite plating with a small amount of N1 and CO, the adhesion of enamel can be further improved without the need for pretreatment. It is based on experimental facts that have been discovered.

Structure of the Invention This invention has a composite plating layer of N1 and CO on the surface of a cold rolled steel sheet, and the amount of deposited N1 and Co is 0.01117'.
m2 to 1.5P/.2 and GO adhesion is 0.
This is a steel plate for enameling that can omit the enameling pretreatment step, which has a rating of 0021/L2 or more.

In this invention, the above-mentioned Ni, Go composite plating is performed after cold rolling and before recrystallization annealing, and by performing recrystallization annealing after this plating, the plated N1
The GO composite plating layer softens and partially diffuses into the steel plate surface.

Therefore, even when performing the treatment without enamel pre-treatment as shown in Figure 1(b), there is no fear that N1 or CO will peel off during press working and the adhesion of the enamel will decrease, and compared to the case where the enamel is plated after annealing, Since Ni and CO are softened, there are advantages such as less cracking in the plating layer and less chance of rusting after press working.

The adhesion between the wax and the iron is maintained by the FeO generated on the surface of the steel sheet being diffused and melted into the glaze, and depends on the concentration of FeO.

The effect of N1 and CO double gold plating on the coating suppresses the amount of FeO generated on the surface of the steel sheet, while after the glaze melts, it forms a local battery of Ni - Fe * Cio - Fe and suppresses the production of FeO. It works to promote and maintain the close contact between chichi and enamel.

Therefore, if the amount of N1 and Go composite plating is too large, rzFeo, which is necessary for enamel adhesion, will be difficult to generate, and if it is too small, it will be difficult to generate FeO during melting of the glaze.

It cannot contribute to the promotion of production.

In other words, there is an appropriate range for the combined amount of N1 and Cjo 4i plating necessary to ensure good adhesion between the enamel and the iron.

As shown in FIG. 2, the adhesion of enamel (evaluated by PE adhesion index (%)) can be increased by a small amount of N1 and Co composite plating. In addition, when re-waxing is applied as shown in the figure, the degree of adhesion decreases significantly, but the adhesion after re-waxing is PEI 〉60%.
If this is the case, the amount of N1 attached will be 0.1 even if N1 is only coated.
Compared to where a fairly good adhesion can be obtained in the range of g/rn2 to 2.09/rn2, when composite plating of N1 and co is applied, the total adhesion amount is 0.017i/1n.
If it is in the range of 2 to 1.59/TL2, PE after wandering again
I〉60% can be secured. Note that if it exceeds 1.59/mz, the adhesion of the enamel will decrease, so the upper limit is i, 5g.
/mg.

The reason for the improvement in adhesion by N1 and Co composite plating is thought to be due to almost the same effect as N1 single plating, but the details are not clear.

Gag during composite plating is 0 as shown in Figure 8.
．． 002 g/Tnz or more is sufficient, but the use of a large amount of GO causes an increase in cost.

In N1 and Co composite plating, the adhesion of the enamel is good even when the N1 plate used as an electrode contains Co.

Note that the material for enamel is not particularly restricted in terms of composition, and either an ingot method or a continuous casting method can be adopted.

The characteristics of the present invention hardly change whether the re-box annealing after N1 and Co composite plating is carried out by glaze annealing, continuous annealing or decarburization annealing.

Furthermore, the steel plate for enameling according to the present invention is characterized in that pre-enameling treatment can be omitted; however, even if pickling is performed as a pre-enameling treatment, the degree of adhesion after enameling is hardly changed.

Example c: o, oos weight %, Mn: 0.15 weight 5
%, S: 0.011%, L: 0.082% by weight, Ti: 0.056% by weight5. A hot-rolled steel plate with a thickness of 2.8 mm, which contains impurities that are unavoidable during the process, is cold rolled to a thickness of 0.8 mm, and after cleaning, it is placed in an N1 plating bath containing NI SO4 as the main component at 0.2 degrees Co9. %, and composite plating of Ni - (Eo) was performed in the range of O to 2.5 V and '2 as the Ni + Co adhesion amount, and continuous annealing was performed at 800 °C x 40 seconds. We made improvements and created a product.

The obtained steel plate was subjected to enameling pretreatment and degreasing without burying) and after degreasing, it was pickled with 10% H2So, (q ooC) for 10 minutes (
The adhesion of the enamel was examined by applying a commercially available T1 glaze directly to the glaze (without Ni flash), and then firing it once and then firing it again. The adhesion of the crawler increases rapidly, and the Ni-Co composite plating is 0.01 to 1.5 even after the re-rolling.
g/Tn2 range and Co adhesion amount is 0.0029/T
When rL2 or more, good adhesion with PEI >60% was obtained.

Effects of the Invention As described above, according to the present invention, the adhesion of the enamel remains extremely strong even after firing many times, and
It is possible to advantageously obtain a steel plate for enameling, which can omit pre-treatments such as pickling and N-editing, which were conventionally considered indispensable to ensure adhesion of the enamel.

[Brief explanation of the drawing]

Fig. m1 (al is a process diagram of enameling construction by the conventional method, Fig. 1 (bl is a process diagram of enameling construction according to the present invention, A comparative chart showing the relationship between P, E, and I (%) after wax firing. Figure 8 shows Co9 degree and P in N1 and Co composite plating.
E.1. (%) FIG.

Claims (1)

[Claims] L has a composite plating layer of Nλ and CO on the surface of the cold rolled steel sheet, and the adhesion of N1 and CO is 0.01VrL2~1.
511/, in the range of 2 and the amount of CO adhesion is 0.0029/
A steel plate for enameling in which an enameling pretreatment step can be omitted, characterized in that the enamel has a rrL2 or more.