JPH02170989A - Manufacture of enameling sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is directed to a method for producing steel sheets for enameling, in particular, by controlling the pickling speed in the pickling process during enameling pre-treatment, the adhesiveness and pins can be improved. The present invention relates to a method of manufacturing a steel plate for enameling, which is characterized by improving holes, bubble defects, etc.

Among steel plates for enameling, the steel plate produced according to the present invention is most suitable for direct one-time application, where pretreatment conditions are particularly difficult to control. Of course, the other two-folds have sufficient characteristics even when used for other purposes.

(Prior Art) Enamel products have excellent corrosion resistance, chemical resistance, heat resistance, abrasion resistance, etc., and are therefore used in a wide variety of applications such as chemical equipment, kitchen equipment, and sanitary equipment. Recently, it has been widely used for the exterior and interior of buildings due to its beautiful appearance.

Here, ``enamel'' is a type of composite material of metal and ceramics, which is made by fusing glassy glaze to the surface of a steel plate.

Before being enameled, this enameled product is pretreated to improve adhesion.

-a The pretreatment consists of four steps: degreasing, pickling, Ni flushing, and neutralization.

In the pickling process, fine irregularities are formed on the surface of the steel plate to improve adhesion due to the anchor effect. In the Ni flage process, Ni is attached to the surface and during firing, a local battery action promotes the reaction between the glaze and the steel plate to improve adhesion.

Control of these pre-treatment steps is important for one-time direct heating, where the finished product is produced in one firing, and it goes without saying that each bath 1ff should be controlled, as well as the pickling loss value, the amount of Ni deposited, etc. I have to keep it.

On the other hand, the pickling speed of a steel plate is determined primarily by the Cu/P ratio, which is the ratio of Cu to P in the steel. In other words, when the Cu/P ratio is high, the pickling speed becomes slow, and when the Cu/P ratio is low, the pickling speed becomes fast.

In order to obtain satisfactory secretion even when directly applied once, it is necessary not only to adequately control the pre-treatment process, but also to make the steel plate have a stable pickling speed on the steel plate side. For this reason, it is important to keep the Cu/P ratio constant.

However, it is usually difficult to control this ratio to a constant value, which results in different pickling rates for each coil.

In the past, several studies have attempted to omit or simplify this pretreatment step. -For example, JP-A-50-4
No. 6526 discloses that after rolling, the surface of the steel plate is coated with Ni or Co, and the steel plate obtained by annealing is enameled to promote the reaction between the glaze and the steel plate during firing to improve adhesion. I tried to raise it. At this time, pretreatment including a pickling step is not necessarily required.

Further, in JP-A-50-53260, the surface of the steel sheet is roughened by performing cold rolling and/or JIJ quality rolling using rolls with roughened surfaces, and the adhesion is improved by the anchor effect.

(Problems to be Solved by the Invention) However, despite these studies, pretreatment is still performed in most cases of direct one-time application, and strict process control is therefore required. Furthermore, since the pickling speed of the steel plate differs from coil to coil, in order to ensure adhesion, the operation is usually carried out with excessive pickling in consideration of safety. As a result, pinholes and bubble defects caused by pickling smut were more likely to occur.

The general purpose of the present invention is based on the recognition that pretreatment such as pickling is rather necessary to produce enamel products of stable quality, and to provide efficient and simple pretreatment for that purpose. It is an object of the present invention to provide a method for manufacturing a steel plate for enameling, which can be carried out in the following manner.

Further, a specific object of the present invention is to provide a method for producing a steel plate for enameling, in which the pickling speed can be easily controlled in the pretreatment pickling step.

(Means for Solving the Problems) Therefore, the present inventors conducted various studies in order to achieve the above object, and found that although the effect of Cu in steel on the pickling rate was conventionally known, It was found that not only Cu attached to the steel sheet surface by means such as plating also affects the pickling speed, and the relationship between the Cu/P ratio and the pickling speed considering the Cu1l of both of them was found. There is a certain quantitative relationship between The present invention was completed based on the discovery that it is possible to achieve good adhesion and reduce pinhole and bubble defects.

In the present invention, various known methods such as substitution, reduction, and electrolysis can be used to attach Cu to the surface of the steel sheet.

Here, the gist of the present invention is that in manufacturing a cold-rolled steel plate for enameling, Cu is applied on the surface of the steel plate after annealing.
(P) (Cu), [P]: Cu in steel, P amount (wt%) Cu:
This is a method for producing a steel plate for enameling, which is characterized by depositing a sufficient amount of deposited Cu1l (g/n?) and controlling the pickling speed in the pickling step during enameling pretreatment.

Another aspect of the present invention is that in producing a cold-rolled steel plate for enameling, after cold-rolling the steel plate, Cu is applied to the surface of the steel plate using the above formula T.
This is a method for producing a steel plate for enameling, which is characterized by depositing only a satisfactory amount of Il, followed by annealing at a temperature equal to or higher than the recrystallization temperature, and controlling the pickling speed in the pickling step during pre-enameling treatment.

From another aspect, the present invention provides a cold rolled steel plate for enameling.
During the pickling process after hot rolling or before cold rolling, Cu is added to the surface of the steel plate (P) (Cu), (P): Cu in steel, Pffi (w
t%) Cu: deposited Cu I (g/rd), R: deposited in an amount that satisfies cold rolling ratio (1), then cold rolled, annealed at a temperature higher than the recrystallization temperature, and pre-enamelled. This is a method for producing a steel plate for enameling, characterized by controlling the pickling speed in the pickling step.

In addition, in the present invention, by depositing Cu on a steel plate, this deposited Cu acts in a similar manner to Cu in the steel,
This method is based on the new discovery that it is possible to control the pickling speed and at the same time form fine irregularities on the surface of the steel sheet. The reason why Cu in steel and Cu attached to the surface have similar effects despite having completely different forms is not clear, but both Cu in steel and Cu attached to the surface can be washed with sulfuric acid. Medium-temperature elution, then (CulS
It is thought that the above effect is obtained by re-precipitation (on the surface of the steel sheet in the form of Cu), and this is considered to be the reason why it is not related to the initial form of Cu.

As described above, according to the present invention, the pickling speed of the steel plate can be stabilized, and therefore, the control conditions during pre-enameling treatment can be relaxed, and the optimal pickling loss value can be aimed at. The skin of the steel plate tends to have a finely uneven surface, making it easy to obtain high adhesion and reducing pinholes and bubble defects.

(effect) Next, we will discuss the reasons for limiting the conditions.

The pickling speed of a steel plate can generally be determined by the Cu/P ratio, but when Cu is deposited on the surface of a steel plate, both the Cu in the steel and the deposited Cu affect the pickling speed and the formation of fine irregularities on the surface. According to the invention, (78x (
A good steel plate for enameling can be produced by controlling Cu) + Cu) / CP).

When this value is less than 80, the pickling speed is too fast and fine irregularities are difficult to be formed on the surface of the steel sheet. The number of pinholes also increases.

If this value exceeds 400, there is a problem that the pickling speed becomes too slow and the pretreatment process takes time. Adhesion also decreases.

In addition, when depositing Cu on a hot-rolled and pickled sheet, the amount of Cu deposited is larger than that on a cold-rolled or annealed sheet, but this is because cold rolling is performed after this, so the amount of Cu in the steel is Although it does not change, the amount of Cul attached to the surface decreases per unit area. Therefore, it is necessary to deposit a large amount.

From the above, (78X (Cu) +Cu)/ (P) and (78(Cu) + ((100-R)/100) x
The value of Cu)/(P) is set to 80 to 400, preferably 200 to 300.

As long as a predetermined amount of Cu can be deposited uniformly over the entire surface of the steel plate, it can be done by electroplating, chemical plating, thermal spraying, or powder sintering rings, but plating is easier. It is preferable because it is large and the amount of adhesion can be easily adjusted.

Cu and Pfit in the steel can be determined in advance from the elemental analysis data of the steel plate to be processed, and their values are calculated using the above equations (11, (
If the value is outside the range of 2), the required amount of Cu is deposited on the surface of the copper plate so that the target value is within the range of the formula.

When pickling a steel plate to which Cu is attached in this way,
As a result of carrying out the necessary and minimum rate of pickling, it is possible to shorten the processing time by approximately 10-20% in terms of pickling time.

The manufacturing process of steel sheets for enameling generally consists of the following steps: hot rolling, pickling, cold rolling, annealing, pickling, and enameling. It can be carried out at any time as long as it is a step before pickling, for example, after hot rolling and before cold rolling, after cold rolling and before annealing, and after annealing and before pickling. There are no restrictions, but from the point of view of ease of operation,
After cold rolling and before annealing.

In the present invention, there are no particular restrictions on the conditions for each step of hot rolling, cold rolling, annealing, pickling, enameling, etc., and any conventional conditions may be used.

Next, the present invention will be explained in more detail with reference to examples thereof.

Example Steels A to J having the composition shown in Table 1 were melted.

The slab obtained by continuous casting was heated to 950 to 1200°C and hot rolled at a finishing temperature of 900°C or higher, and then the steel D-G was rolled up at 630°C and the rest at 500°C.

After removing scale by pickling, cold rolling was performed with a reduction amount of 75%, and after cold rolling, annealing was performed. Steel A~C,, Steel H-
For J, box annealing was performed at 700°C for 8 hours, and steel D-
For G, continuous annealing was performed at 830°C for 60 seconds.

Cu deposition occurred after pickling prior to cold rolling for steels E, G, and H, and after cold rolling for steels A and DSJ.
For steel B%C, F, and 1, after annealing, Log
/ I CuSO4・5H! This was done by displacement plating in 0 solution.

For enameling, after degreasing, it was pickled with a 13% sulfuric acid aqueous solution at 70°C for 5 minutes, Ni flashed, glazed, and fired. The glaze used was Type 1553C manufactured by Nippon Ferro Co., Ltd., and was fired at 830° C. for 3 minutes and evaluated by applying it once.

The characteristics of the enamel layer of each of the enamel steel plates thus obtained were tested.

Adhesion was evaluated using a PEI tester, and the presence or absence of pinholes was visually inspected.

The results are summarized in Table 2 together with the pickling loss (also referred to as acid Ml).

FIG. 1 is a graph summarizing the results of Table 2 for equations (1) and (2). .

As described above, it can be seen that according to the present invention, a stable pickling range value is exhibited, and as a result, it is excellent in high adhesion and pinhole properties.

(Effects of the Invention) According to the present invention, even if there are variations in the components (Cu, PM), a stable pickling rate can be obtained by depositing Cu accordingly, and at the same time, fine particles can be left on the surface after pickling. It is easy to form unevenness, and therefore high adhesion can be obtained. In addition, since the optimum pickling loss detection area can be targeted, pinhole defects can be kept to a minimum.

[Brief explanation of the drawing]

FIG. 1 is a graph summarizing the results of Examples and showing the relationship between Cu, Pi and enamel properties.

Claims (3)

[Claims] (1) When manufacturing cold-rolled steel sheets for enameling, Cu is applied to the surface of the steel sheet after annealing at 80≦(78×[Cu]+Cu)/[P]≦400[C]
u], [P]: Cu in steel, P amount (wt%) Cu: Adhesive C
A method for producing a steel plate for enameling, characterized by depositing only an amount that satisfies the amount of u (g/m^2) and controlling the pickling speed in a pickling step during pre-enameling treatment. (2) In producing cold-rolled steel sheets for enameling, Cu is added to the surface of the steel sheet after cold rolling at 80≦(78×[Cu]+Cu)/[P]≦400[C]
u], [P]: Cu in steel, P amount (wt%) Cu: Adhesive C
A steel plate for enameling, characterized in that an amount satisfying the amount of U (g/m^2) is deposited, and then annealing is performed at a temperature higher than the recrystallization temperature, and the pickling speed in the pickling process during enameling pretreatment is controlled. manufacturing method. (3) When manufacturing cold-rolled steel sheets for enameling, carbon is added to the surface of the steel sheet during the pickling process after hot rolling or before cold rolling.
u is 80≦(78×[Cu]+{(100-R)/100}
×Cu)/[P]≦400[Cu], [P]: Cu in steel
, P amount (wt%) Cu: Adhering Cu amount (g/m^2), R
: Deposit only the amount that satisfies the cold rolling rate (%), then perform cold rolling, and then annealing at a temperature higher than the recrystallization temperature to control the pickling speed in the pickling process during enameling pretreatment. Characteristics of the manufacturing method for steel plates for enameling.