JPS63132729A - Steel plate excellent in workability-corrosion resistance-clear reflection - Google Patents

Abstract

PURPOSE:To give an excellent workability, corrosion resistance and clear reflection to a steel plate by making the mean waviness of the filter wave of the surface of a steel plate and the plane roughness in a specific range. CONSTITUTION:The surface of a steel plate is adjusted so as to attain to <=0.7mum mean waviness (Wca) of a filter wave and 0.4-0.8mum mean roughness (Ra). The holding amt, of an oil is increased by the unevenness formation on the surface of this steel plate, the direct metal contact part with a jig is reduced even for the seizure or die galling phenomenon at pressing time and a lubrication oil can be unitized sufficiently. Consequently this steel plate becomes of high clear reflection and of excellent workability and corrosion resistance as well.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a steel plate with excellent workability, corrosion resistance, and sharpness.

[Conventional technology]

Normally, steel plates (hot-rolled steel plates, cold-rolled steel plates, electroplated steel plates, hot-dip galvanized steel plates, etc.) are often coated to provide corrosion protection, design, functionality, etc. in the final specifications. .

In recent years, there has been a high demand for "sharpness (or sharpness)" of painted steel sheets, which is one of the factors in design. This image clarity is a measure of how clearly and without distortion the image of an object appears on a painted surface or a plated surface such as Cr foil. As an indicator of the quality of a paint finish, it is an important characteristic that determines the aesthetics of car body paints and home appliances.

Conventional methods for obtaining high image clarity are as follows.

(1) Measures depending on the painting method ■ Coil painting: Adoption of curtain flow one-way method rather than roll coating method ■ Adoption of electrostatic coating method rather than batch coating spray coating method ■ Paint film thickness: Increased film thickness (e.g. thick electrocoating) etc.) (2)
Countermeasures using paints ■ Adoption of paints with high reflow properties (especially flowability during baking drying) ■ Improving sharpness by adjusting pigment particle size, content, species, etc. ■ Uniform aggregation of coating surface by resin type (cured resin) (3) Countermeasures based on the material surface, for example, adoption of surface-smooth (e.g. bright rolled) steel plates Among the above-mentioned countermeasures, when limited to automotive coatings,
The contribution rate of the effect on sharpness is 36.1% for steel plate (or steel plate roughness) pre-treatment (chemical conversion treatment etc.)
2.1% painting (3 coat system) 4
It has been analyzed to be 0.4%. In addition, it can be easily estimated that especially when the coating film thickness is thin, the contribution rate to the steel plate becomes high.

As a method of dealing with material surfaces, it has long been confirmed that ideally a perfectly mirrored object (for example, a so-called mirror) can provide the best sharpness, and if this method is limited to steel plates, Then, the final process of surface smoothing treatment (
For example, it is known that it is optimal to perform brightening treatment (rolling). Furthermore, the same thing applies to electroplating as there is no difference between the roughness of the base material and the roughness after plating (Japanese Unexamined Patent Publication No. 61-67794).

On the other hand, in order for the steel plate surface to have oil retention and seizure resistance, the presence of an uneven surface on the steel plate surface is an important factor. In other words, the uneven surface has a larger surface area than a perfectly mirrored surface, which increases the amount of oil it can hold.
Regarding the phenomenon of "seizure" or "mold galling," the direct metal contact area with the jig is reduced, and oil lubrication can be fully utilized.

[Problem that the invention seeks to solve]

However, in terms of materials, so far only high-definition improvements have been studied;
Even in Publication No. 94, the surface roughness is only specified to be 0.25 μm or less, and no consideration is given to the above-mentioned press workability or the like. Therefore, the reality is that a steel plate that has both of these properties has not been obtained.

Therefore, the main object of the present invention is to provide a steel plate that not only has high image clarity but also has excellent workability and corrosion resistance.

[Means for solving problems]

The present invention aims to solve the above-mentioned problems, and the filtered average waviness (Hca) of the steel plate surface is 0.7 μm or less, and the average roughness (
Ra) is 0.4 μm to 0.8 μm.

In the present invention, as shown in FIG. 1, the filtered average waviness (Wca)
and average roughness (Ra) within a specific range.

The reason for specifying this range will now be explained in detail based on various experimental results.

In addition, the filtered average waviness (Wca) referred to in the present invention is the center line average value of the filtered waviness curve (JIS B0610-1
976), and the average roughness (Ra) can be measured by the center line average value of the roughness curve (JIS 80601-1982).

The test materials used in the experiment were (a) 0.8 mg+t cold rolled steel plate, (o) 1.6 l1jt cooled steel plate, (
h) Electric Zn-plated steel plate with 0.8 fin t (plating weight 12
0 g/rrr) , (=) Q, 13 wm t electric Zn-Ni plated steel plate (plating area weight 20 g/rrr)
It was done using .

First, the image clarity of the test materials (a) to (=) above was examined. The evaluation of sharpness was made by Suga Test Instruments ICM-
Using 20P (optical comb 0.5+n), 2 coat bake: ◎≧50>○≧35>△≧15>X3 coat 3
For baking, ◎≧65>○≧40≧△. Also, Ra
and -ea were measured using 5E-3 (cutoff 0.4 m) manufactured by Koita Research Institute.

The results are shown in Figures 2 and 3, and Wca is 0.
．． It can be seen that image clarity is excellent when Ra is 7 or less and Ra is 0.8 or less. 2 and 3 are based on the coating conditions of 2 coats, 2 bakes and 3 coats, 3 bakes shown in Table 1.

On the other hand, the relationship between the surface roughness Ra and the amount of residual oil, and the relationship between the amount of residual oil and the incidence of red rust were investigated. The sample materials are (a)
~(d). The test method is as shown in Figure 4, where base oil for rust prevention oil (viscosity 15 cSt-25
℃) and a load of 100 kglof was applied, the oil seeped from the edge of the steel plate was removed, and the amount of residual oil was examined after holding the same load for 3 days. Result is,
It was as shown in FIGS. 5 and 6. When Ra is large, the amount of residual oil tends to increase and the incidence of red rust decreases.

In addition, the red rust occurrence test (corrosion resistance test) was performed at 50°C x 95%
RHX was carried out on only the test materials of (a) and ([1)] under the conditions of 15 days.

Furthermore, regarding surface roughness (Ra) and seizure resistance, (0)
It was investigated using the sample materials. The test method is as shown in Figure 7.
A sample material coated with a thin layer of anti-corrosion oil was placed between the temporary presser and the gouer, and drawing was performed by applying pressure with a punch. In this case, the gap was 1.48 liters and the ironing rate was 7%. Regarding the material after this processing, as shown in FIG. 8, the survival rate of normal parts per 50 cranes excluding the burnt part bn formed on the outer surface was determined.

n Normal area survival rate (%) = (1 - Σ =) x 100 The results are shown in Figure 9. From this, it can be seen that when Ra is 0.4 μm or more, there is less burning.

Comprehensive judgment of the above results and other results not shown shows that for image clarity, Wca is 0.6 μm or less and Ra is 0.8 μm or less, and for corrosion resistance, Ra is 0.4 μm or less.
It was found that it is preferable for the workability to be 77 m or more and for Ra to be 0.35 μm or more. Therefore, in order to satisfy all the characteristics, the following conditions are required: ca≦0.7 μm 0, 4 pm≦Ra≦0.8 pm.

〔Effect of the invention〕

As described above, according to the present invention, a steel plate having excellent workability, corrosion resistance, and sharpness can be obtained.

[Brief explanation of the drawing]

Figure 1 is a relational diagram showing the range according to the present invention, Figures 2 and 3 are experimental results regarding image clarity, Figure 4 is an explanatory diagram of the test method for residual oil amount, Figures 5 and 6 The figure is a diagram showing the test results regarding corrosion resistance, FIGS. 7 and 8 are diagrams explaining the test method for workability, and FIG. 9 is a diagram showing the test results for workability. Patent Applicant Sumitomo Metal Industries Co., Ltd. Agent Patent Attorney Yoshi Nagai Figure 1 Ra (μm) Figure 2 9α (μm) Figure 3 Rcjgm) Figure 4 0*t100kg/cm2 Figure 5 Rα (μm) Figure 6 Aj quantity Tgr/rn2) Figure 7 Figure 8 Figure 9 Rα (J!m)

Claims (1)

[Claims] (1) Filtered average waviness (Wca) on the steel plate surface is 0.7μ
m or less, the average roughness (Ra) is 0.4 μm to 0.8 μm
A steel plate with excellent workability, corrosion resistance, and image clarity.