JPH0293047A - Steel sheet for enamelling - Google Patents

Abstract

PURPOSE:To obtain the title steel sheet having good enamelling characteristics and press workability by specifying the contents of C, Mn, P, S, sol. Al, N, Ti, Cu, Ge, Sn, As and Sb and forming the balance with Fe. CONSTITUTION:The compsn. of the steel sheet is formed with, by weight, <=0.005% C, <=0.4% Mn, <=0.01% P, <=0.01% S, <=0.08% sol. Al, >=0.005% N, 0.03 to <=0.3% Ti, total 0.01 to 0.1% of one or more kinds among Cu, Ge, Sn, As and Sb and the balance substantial Fe. In the Ti-added steel, when the steel sheet in which both of the P and S contents are lowered to <=0.01% as well as to which one or more kinds among Cu, Ge, Sn, As and Sb are added is pickled, a fine rugged surface can be obtd. and actual adhesion is drastically improved, by which the steel sheet for enamelling having good enamelling characteristics and furthermore having excellent press workability can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cold-rolled steel sheet for enameling that has excellent workability and enameling adhesion and can be used even in severe applications such as single-rolling. Enamel products have excellent corrosion resistance, chemical resistance, heat resistance, and wear resistance, so they are used in chemical equipment,
It is used in a wide variety of applications, including kitchen equipment and sanitary equipment.

(Prior Art) Enamel steel sheets, which have a vitreous glaze baked onto the surface of the steel sheet, are widely used in kitchen appliances, bathtubs, gas appliance parts, etc., and recently, in the interior and exterior of buildings. The steel plates used for enameling are required to have good cold workability and enameling properties. As for the characteristics of enamel,
Steel sheet properties are required to prevent surface defects such as bubbles, black spots, and pinholes that occur during enamel firing, as well as nail chips that occur after firing, and to have good adhesion between the steel sheet and glass.

It is disclosed in Japanese Patent Publication No. 18066/1973 that a steel plate with excellent deep drawability can be obtained by adding Ti to ultra-low carbon steel, and attempts are being made to use this steel plate with excellent workability for enameling. Various studies have been conducted.

As an example, in JP-A-61-104051, As...
By adding Sb and Bi, it is intended to prevent smut from adhering to the surface of the steel sheet during the sulfuric acid pickling process during enameling pretreatment and improve adhesion.

Furthermore, Japanese Patent Application Laid-Open No. 110845/1984 attempts to reduce the amounts of S and P to improve bubble defects and adhesion.

(Problem N that the invention attempts to solve) However, despite these studies, Ti-added steel sheets
One-time direct heating is not used in the process, as the enameling properties such as adhesion are not stable, and the product can be completed after two firings, which is quite severe.

Therefore, an object of the present invention is to provide a steel plate that focuses on adhesion among the enameling properties, has sufficiently stable adhesion even when applied directly and repeatedly, and has an excellent enameled appearance, and a method for manufacturing the same. It is.

(Means for Solving the Problems) The present inventors focused on the surface texture after the pickling process during enameling pretreatment, and investigated the component system and process conditions that would yield a finely uneven surface with good adhesion. did.

As a result, in Ti-added steel, both P and Sl in the steel were reduced to 50.01% while Cu, Ge, S
By adding one or more of n, As, and sb, a fine uneven surface can be obtained on the steel plate surface in a wide range of pickling loss value of 10 to 100 g/n (PUT).
The present invention was completed based on the discovery that the test value (test value) was also significantly improved.

Here, the present invention provides the following conditions in weight%: C≦0.005, Mn≦0.4, P amount 0.01, S≦0.01, sol. Al≦
0.08, Na3.005.0.03≦Ti≦0.
3. Processing consisting of one or more of Cu, Ge, 5nSAs, and sb with a total of 0201 or more and 0.1 or less, and optionally 0.0003≦B≦0.002 residual iron and unavoidable impurities. For enamel with excellent adhesiveness and enamel adhesion.
It's a betrayal.

Further, the present invention provides steel having the above composition that is hot-rolled, then coiled at a temperature of 500°C or higher, pickled, cold-rolled, then rolled at a temperature higher than the recrystallization temperature.
This is a method for producing a steel plate for enameling, which has excellent workability and enameling adhesion, and is characterized by annealing at three points or less.

The reason why the enamel adhesion is improved in this way in the present invention is not clear, but it is speculated as follows.

Conventionally, in the case of rimmed steel sheets, such fine irregularities were formed by the interaction between P, which increases the pickling rate, and Cu, which decreases it, but in the Ti-added steel sheet of the present invention, the former effect is a Ti compound (e.g., TiC,
, TiN, TiS, TiP (TiFeP), etc.)
However, the latter action is Cus Ge5Sns^s, Sb
It is assumed that this is in charge.

In other words, a large amount of N is added to Ti-added steel sheets for enameling to improve the nail-flying resistance, but this increases the pickling speed and makes it difficult to form fine irregularities, rather making it easier to form etch pits. Therefore, the pickling loss value range with good adhesion becomes narrower.

In the present invention, S and P are reduced in order to suppress this problem, but with this alone, it is difficult to form fine irregularities with good adhesion after pickling. Therefore, C reduces the pickling speed.
It is necessary to add u, Ge, Sn, and 45% Sb, and the addition of these elements forms fine irregularities after pickling due to interaction with the Ti compound, resulting in a wide range of acids.
(exhibits excellent adhesion to am).Also, if Cu, Ge, Sn, As, Sb, etc. are simply added and the pickling speed is suppressed to the same level as that of rimmed steel sheets, 50 to 60 g
At pickling weight loss values of / = or above, fine irregularities are formed <<a? Adherability decreases.

Therefore, while reducing the amount of S and P, CL1%
It is necessary to add 45% Ges Sns and at least one of sb.

(Function) Next, the reason why the 'w4 composition and heat treatment conditions are limited as described above in the present invention will be explained.

C: The amount of C in steel is closely related to the occurrence of pinholes in enamel defects, and when a large amount is present, many pinholes will occur. However, if it is less than o, oos%, there is no risk of this happening.

Mn: Mn is an element necessary to improve hot embrittlement, but as Mn1l increases, the steel becomes hard, so the upper limit was set at 0.4%.

sol. Al: As the amount of sol and All increases, press formability deteriorates, so the upper limit was set to 0.08%.

N: N is an element added to prevent nail skipping during enamel defects. In steel, N forms a compound with Ti to become TiN, which traps hydrogen in the steel that causes nail flying. Therefore, the lower limit is set to 0.005%. The upper limit is not particularly limited, but is generally 0.0120%.

Ti: As mentioned above, Ti prevents nail skipping as TiN, and at the same time forms a compound with c, s, p, etc., and improves press workability. If it is too low, the resistance to chipping and workability will deteriorate, and if it is too high, there will be problems such as increased costs and a tendency for continuous casting nozzles to become clogged. Therefore, 0.03%
≦Ti≦0.3%.

S, P: SSP is an element that is harmful to forming fine protrusions on the surface of the steel sheet after pickling. S in Ti-added steel
Alternatively, if the amount of P is large, etch pits will be formed on the surface of the steel plate after pickling, resulting in a skin that is disadvantageous for adhesion, and the adhesion rate (PH1 test value) will also decrease. However, if both 81P and 81P are 50.01%, their harmful effects can be ignored.

Cus Ge5Sns^s, Sb: These elements are effective for forming fine irregularities on the surface of the steel sheet after pickling. Simply lowering s and pl will not form fine irregularities and will result in a wide range of pickling weight loss values (10 to 100).
g/rd>, a good adhesion rate CPEI value>80%) cannot be obtained. Therefore, it is necessary to add at least one of these elements. If the total of these is 0.01% or more, it is effective in forming fine irregularities. Furthermore, even if the total amount exceeds 0.1%, the effect not only becomes saturated, but also the pickling speed decreases significantly, which is not preferable in terms of enameling work efficiency.

It is desirable to add BIB when there is a risk of secondary processing embrittlement, and there is no effect if the amount added is less than 0.0003%. Furthermore, if it is added in an amount exceeding 0,002%, not only the effect will be saturated but the T value will decrease. Therefore, when adding B,
0.0003% or more and 0.002% or less.

Next, in the manufacturing method according to the present invention, the steel having the above-mentioned components (ingot or slab) is hot-rolled at 500°C.
The reason for winding at the above temperature is to fix the solid solution carbon in the steel with Ti and improve workability. In addition, the annealing method is
There is no particular difference between the box annealing method and the continuous annealing method, and it is sufficient to anneal at a temperature higher than the recrystallization temperature and lower than the Acs point.If the temperature range is outside this range, the workability will be significantly deteriorated.

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

Examples After casting steel having the components shown in Table 1, the slab was heated at 1150°C, hot rolled at a finishing temperature of 900°C or higher, and then coiled at 600°C. After pickling and cold rolling (75%) in a normal process, continuous annealing at 820°C for 60 seconds or box annealing at 730°C for 15 hours was performed.

In addition, the recrystallization temperature of these series of steels (70
0 to 750°C, and 620 to 670°C for the box annealing method). Tensile tests and enameling property tests were conducted on the sample materials obtained in this way, but the difference in enamel properties due to the different annealing methods was Since no particular findings were observed, the results for the continuously annealed material will be shown below.

Table 2 shows the enamel properties (adhesion rate, nail skipping), surface unevenness after pickling, and JIS S tensile test results.

Enamel properties were obtained by cutting a steel plate into 100 mm squares, degreasing and pickling (15% 1bsOa, 75°C) as pre-treatments,
After performing Ni flash and neutralization, evaluation was performed by direct coating using glaze type 1553C manufactured by Nippon Ferro Co., Ltd. The film thickness was 120±10/Jl.

Adhesion was measured using a PEI tester, with a pickling loss value of 20g7M.
The value of the hour was shown.

FIG. 1 shows the relationship between the pickling amount value and the adhesion rate (PH1 value) for representative steel types in the examples.

The occurrence of nail flying was investigated one week after firing. The surface unevenness was observed with a scanning electron microscope (SEM) after pickling at 20g/rd, and a) cases where the surface was uneven like steel grade E were indicated with (Yes), and b) cases where the surface was uneven like steel grade E were indicated. The case where an etch bit was formed is indicated by (none). The respective electron micrographs are shown in Fig. 2+al and fbl (x1000x).

As is clear from the above, the steel of the present invention has fine irregularities formed on the surface after pickling and exhibits good adhesion over a wide range of pickling weight loss values.

Furthermore, the press workability is also good as shown in Table 2.

Table 2 Enamel properties and mechanical properties It has enameling properties and also has excellent press workability, and can be used directly in one-pass processes, and can also be used in applications that require particularly severe workability.

[Brief explanation of drawings]

FIG. 1 is a graph showing the results of the example; and FIG.
al and the same figure (bl are steel types E and D of the example, respectively)
This is an electron microscope photograph of the metal Mi weave (x1000 magnification).

Claims (3)

[Claims] (1) In weight%, C≦0.005, Mn≦0.4, P≦0.01, S≦0.01, sol. Al≦0.08, N≧0.005, 0.03≦
Ti≦0.3, one or more of Cu, Ge, Sn, As, and Sb whose total is 0.01 or more and 0.1 or less, remaining iron and unavoidable impurities, workability, enamel adhesion A steel plate for enameling with excellent properties. (2) Furthermore, 0.0003≦B≦0.002 in weight%
The steel plate for enameling according to claim 1, which contains the following. (3) The steel having the steel composition according to claim 1 or 2 is coiled at a temperature of 500° C. or higher after hot rolling, pickled, cold rolled, and annealed at a temperature higher than the recrystallization temperature and lower than Ac_3. A method for producing a steel plate for enameling that has excellent workability and enameling adhesion.