JPH0436476A - Production and device of steel sheet having amorphous surface layer - 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] [Field of Industrial Application] The present invention relates to a method for manufacturing a steel plate in which the surface portion of an anodized Ni-Zn alloy plated steel plate is rendered amorphous by irradiation with laser light. Regarding the device.

[Conventional technology]

Ni-Zn alloy plating is widely used because of its excellent corrosion resistance. However, since the plated surface is white or grayish-white, there are restrictions on its use for naked use. On the other hand, in recent years, there has been a strong demand for bare use in applications such as home appliances, and for this reason, blackened steel sheets that have a black appearance have come into widespread use.

As this blackening treatment method, in addition to a method of coating with a black resin film and other methods, a method of blackening by anodizing treatment is also known.

The present applicant has previously proposed a method for producing a blackened steel sheet with even better color tone in Japanese Patent Application Laid-Open No. 110798/1983.

On the other hand, it is known that when the surface of a steel sheet is made amorphous, there is a significant improvement in corrosion resistance, weather resistance, design, etc. The alloy layer can be made amorphous by rapidly heating and melting the surface and then rapidly cooling it.

In this regard, the present applicant has published Japanese Patent Application Laid-Open No. 61-69938.
No. 1, it was disclosed that when making a Ni-based alloy amorphous, the surface portion is irradiated with laser light and then immediately cooled with gas.

[Problem to be solved by the invention]

However, since the surface of the Ni-Zn plated steel sheet to which the present invention is applied is white or grayish-white as described above, even if the surface is irradiated with laser light according to the conventional technology, the absorption of laser light will not occur. The amount is small, requiring irradiation at high power, and even if irradiation is performed at high power, it is difficult to form a sufficient amorphous layer.

Therefore, an object of the present invention is to reliably form a desired amorphous layer even when irradiated with a laser beam of low output.

[Means to solve the problem]

In order to solve the above problem, the anodized surface of an anodized NiZn-based alloy plated steel sheet is irradiated with laser light to melt the surface, and then rapidly cooled to form an amorphous layer. This can be solved by letting

Further, in terms of the device, there is a feeding means for feeding out the anodized Ni-Zn alloy plated steel sheet with the anodized surface facing downward, a winding means for the same, and a winding means between the feeding means and the winding means. A laser beam irradiation means for irradiating a laser beam onto the anodized surface facing downward of the steel plate, and a cooling means for bringing liquid nitrogen into contact with the surface opposite to the laser beam irradiation surface substantially downstream from the laser beam irradiation position. This can be solved by having the following.

[Effect]

In the present invention, in particular, a Ni--Zn alloy plated steel sheet is anodized, and the anodized surface is irradiated with laser light.

The anodized surface has a black color, which increases the energy absorption efficiency of the laser light. Moreover, since the anodized surface is extremely thin (less than 1 μm), it melts quickly when irradiated with laser light, and when the underlying plating layer is exposed, it increases the reflectance of the laser light, which absorbs the laser light. The efficiency decreases in a very short period of time, and when combined with the use of cooling means,
The cooling effect is excellent, which satisfies the conditions for sufficient amorphization, and the advantages of the laser beam irradiation method become apparent.

Further advantageously, since the anodized surface is black and has large irregularities, it acts as a nearly perfect black body for the irradiated laser beam, and has extremely high energy absorption efficiency of the laser beam.

[Specific structure of the invention]

The present invention will be explained in more detail below with reference to the drawings.

FIG. 1 shows an example of the apparatus of the present invention, in which a Ni--Zn alloy plated steel plate is produced in advance by electroplating or the like, and this plated steel plate is subjected to an anodizing treatment.

Such anodized Ni-Zn alloy plated steel sheet 1
is fed out from the feeding roll 2 with its anodized surface 1a facing downward. This steel plate is made amorphous by an amorphizing means described below, and then wound up by a take-up roll 3.

The anodized surface 1a is located between the feed roll 2 and the take-up roll 3, and is irradiated with laser light by a laser light irradiation means 4 from below. The laser beam is scanned in the width direction of the plated steel plate l. On the surface opposite to the surface irradiated with this laser beam, in a specific example, on the top surface,
A cooling means 5 is provided that brings liquid nitrogen into contact substantially downstream from the laser beam irradiation position.

The cooling means 5 specifically includes a storage tank 5 containing liquid nitrogen N.
A, a sealing means 5B for sealing between the bottom wall and the steel plate 1, a pump 5C for constantly updating the surface of the steel plate 1 and liquid nitrogen N to enhance the cooling effect, and irradiation of the liquid nitrogen N with laser light. It is equipped with a circulation path 5D that projects the image to the position. The liquid level of liquid nitrogen N is always aligned with the irradiation position of the laser beam.

On the other hand, in order to prevent the laser beam from scattering due to haze and dust generated when the laser beam is irradiated onto the steel plate l, a fan 6 is used to blow air at the laser beam irradiation position in order to eliminate the haze and dust. It is like projecting.

Under the apparatus configured in this way, a laser beam such as a CO2 laser, YAG laser, or glass laser is scanned in the width direction of the steel plate by the laser beam irradiation means 4 on the anodized surface 1a with an output of about 1 to 5 W. It is irradiated while being irradiated.

This irradiation quickly reduces the diameter to 1 μm or less, usually 0.1 μm.
The anodized surface of about m is melted, and at the same time, liquid nitrogen N is used to cool the opposite surface. The melting thickness due to laser beam irradiation is in a shallow range of about IO μm because the plated surface is exposed by melting. In this way, an amorphous layer is formed in an extremely thin portion of the surface of the steel plate 1.

In the present invention, a small amount of laser light is sufficient for laser light irradiation. Therefore, continuous pulse oscillation without using a Q switch is possible. Further, in the above example, cooling was performed using liquid nitrogen, but it is also possible to perform cooling using other cooling media. Furthermore, as a cooling device, a cooling medium may be projected onto the surface of the steel plate. On the other hand, although it is desirable to perform cooling from the surface opposite to the surface irradiated with the laser beam, it is possible to cool the anodized surface directly or while cooling from the opposite surface.

〔Example〕

Next, the effects of the present invention will be clarified through examples.

In the process of manufacturing a Ni-Zn alloy electroplated steel sheet with a thickness of 0.5 to 1.5 mm and a width of 914mm, the final plating was anodized to obtain a blackened steel sheet. The plating bath composition and anodizing conditions are the same as in Example 1 in JP-A-61-110798.

The blackened steel plate is treated with the apparatus shown in FIG.
It was made amorphous. The conditions at this time are as follows.

(1) A continuous pulse oscillation method is used for the C02 laser without using a Q switch.

(2) Power density: I G5W/at (3) Irradiation spot area: 1O-5cnr (4) Irradiation time: 10-7 seconds per spot (5) Scanning speed: 3X10'an/second (6) Steel plate speed: 1.5-2.0ao 7 seconds (7) Cooling rate: 107-10'' for 7 seconds As a result, clear formation of an amorphous layer was observed on the surface portion.

On the other hand, the level of laser light output that can form a similar amorphous layer on a steel sheet that has not been blackened by anodizing treatment was investigated.

As a result, it was found that a power of about 5W was sufficient according to the present invention, whereas it was 40W for a steel plate that was not black-treated. In addition, the laser beam diameter is 0.20 x 10-”an for steel sheets that are not black-treated.
However, according to the present invention,
It has been found that it can be increased to 0.56xlO''Cm.

〔Effect of the invention〕

As described above, according to the present invention, a desired amorphous layer can be reliably formed even by irradiation with a low-power laser beam.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an example of the apparatus of the present invention. ■... Steel plate, 2... Feeding roll, 3... Winding roll, 4... Laser light irradiation means, 5... Cooling means.

Claims (2)

[Claims] (1) The anodized surface of an anodized Ni-Zn alloy plated steel sheet is irradiated with laser light to melt the surface and rapidly cooled to form an amorphous layer. A method for manufacturing a steel sheet having an amorphous surface layer. (2) a feeding means for feeding out an anodized Ni-Zn alloy plated steel plate with the anodized surface facing downward;
a winding means; a laser light irradiation means for irradiating a laser beam onto an anodized surface facing downward of the steel sheet between the feeding means and the winding means; and a surface opposite to the surface irradiated with the laser beam. A manufacturing apparatus for a steel sheet having an amorphous surface layer, comprising a cooling means for bringing liquid nitrogen into contact substantially downstream from a laser beam irradiation position.