JPS58141370A - Alloying treatment of galvanized steel plate - Google Patents

Abstract

PURPOSE:To reduce an alloying time considerably by heating the galvanized surfaces of a steel strip which are galvanized continuously, quickly by irradiation of laser light thereby alloying said surfaces. CONSTITUTION:A steel strip X is electrolytically washed and pickled 20 and is then galvanized in an electroplating cell 21, and the galvanized strip is passed through a scrubber 22. The plated surfaces of the strip X past the scrubber 22 are dried with a dryer 30, whereafter laser light is irradiated to the dried surfaces from above and below or from either above or below to heat the surfaces quickly. The strip X of which the plated surfaces are alloyed by such quick heating is cooled 32 and is then phosphated 23 and rinsed 24, whereby the treatments are finished. The length of the longitudinal pass in the galvanizing line is reduced and the line is made compact by the above-mentioned method; in addition, the traveling speed of the strip is increased.

Description

[Detailed Description of the Invention] This invention relates to an alloying treatment method for galvanized steel sheets.In recent years, there has been an increasing demand for alloyed galvanized steel sheets for the purpose of improving the corrosion resistance of automobile circumferences and outer IIO.Galvanized steel sheets Regarding the alloying of
The K-dipped steel strip is heated again to near SSO℃, soaked, and F
・-Method of forming a Znn all-gold layer, ■Method of applying electrical lead plating to nine steel strips, ■Method of performing offline conversion treatment,■
There is a method of directly plating the entire gold layer of F.-znn in an electrometallurgical chamber, but the above-mentioned method 007 is generally used with 0 points such as intentionality.

Therefore, regarding the above method ■07j, a typical non-oxidized one-type O
Figure 1 IIK shows the twin configuration of the #I galvanized plating line. In Figure 1, (1) is the non-oxidizing heating zone, (2) is the reducing IF and slow cooling zone, (3) is the gas jet cooling zone, and (4) is the zinc %(5) is a direct-fired galvanil furnace and a heat-retaining element.
-), (l is a gas jet cooling zone, (7) is a forced air cooling zone. Φ alloyed galvanized steel strip (X)
Heating again in the vicinity of SSO°C in a galvanized furnace and soaking is carried out by 7.Therefore, the length of the vertical path from the zinc pot to the 10-hole is determined by the alloying process. 1 for work-proximity galvanized medium steel plate
In order to respond to the expansion of the Australian market, it has become necessary to increase the speed of the 1-metal line to increase the yield rate to 0.In order to increase the speed of the twin furnaces, the galvanic furnace using the conventional heating method has been Either the extension of the line is unavoidable and the accompanying increase in the vertical path length O leads to an increase in the number of lines, or steel 1
There is a surface problem due to uneven heating due to increased zero position fluctuations or contact with the furnace body. Therefore, the metallization processing time is significantly shorter than the conventional alloying processing time of 15 seconds before 11. If so, it is possible to make the line more compact!
Not only that, but it can also handle faster line speeds more favorably than the conventional direct-fired heating type O galvaneal furnace, and its industrial value is extremely high.

For the above electrogalvanized steel 1[0 alloying, no alloying layer technology has been developed that is cost-effective on an industrial scale, and low-temperature, long-time O alloying treatment is performed off-line. The present invention is based on the above-mentioned viewpoints, and it is dangerous that the present invention is made based on the above-mentioned viewpoints. When irradiated with laser light and rapidly heated, there is a 40" tI which made it possible to significantly shorten the time required for p-alloying. This makes it possible to reduce the a-condensation of the galvanil furnace in the hot-dip galvanizing line. However, it is possible to perform in-line O alloying treatment on an electrolytic galvanizing line. For the purpose of showing an example, the number is given between 〇%t) K line - 〇 number, which is the same as the iml in lll.

In the 211th & 211th, instead of the conventional direct fire heating type galvanil furnace, we adopted a laser heating type galvanil furnace.
Galvanized steel strip (X) C) Plated 1liK
Rapid heating is performed by irradiation with laser light, and plating lIO alloying treatment is performed.

In 801, the line speed [
Showing the thermal history of a lead-plated steel bud in the vertical path from the hot zinc bot exit side to the gas jet belt exit side when over-plated at 80°C.
It takes about 15 seconds to heat and soak the pigeon house and TLI/II metal copper strip alloyed in step 8) from about 450°C to about 560'C to complete alloying. Including the gas jet cooling time after the chemical treatment, the threading time in the vertical pass was about 20 to 25 seconds. On the other hand, when using the laser heating type galvanil furnace αQ, it is possible to heat the plating layer in a short time, so compared to conventional methods, the heating temperature can be raised and the desired alloying can be completed in a short time.・Figure 4 shows the heating temperature and the time required for alloying.At about 590℃, alloying can be achieved by heating for about 4 seconds and soaking, and rapid heating is not necessary. The progress of alloying during the heating process can be suppressed and the range of optimal alloying time can be expanded, which is advantageous in terms of process control.

Figure 5 further shows the effects of the present invention described above! ! This is to ensure that the zinc weight is 30 f/- and 120 t/-.
In the case of , the alloying rate (evaluated by the residence time of the copper strip and the F content in the plating layer when heated by the conventional method using direct flame heating and the method using the laser heating of the present invention) Optimal range I!2 8-15%) is shown. By performing laser heating, the temperature reaches 590° C. in about 2 seconds, and the optimum alloying region is reached by alloying for 3 seconds or more.

In this case, four 3KW (20) lasers are arranged in a staggered manner on each side of the steel strip surface as a laser oscillation device, and the laser light is collected into 5 true beams by an optical system consisting of a lens and a reflecting mirror. The steel strip was irradiated while scanning at high speed in the width direction of the copper strip.As is clear from the figure, this is the case of laser heating.

Because the output is easy to control, alloying can be completed in almost the same time regardless of the basis weight K. Since the furnace temperature is low and cooling by the steel base can be expected, it is possible to Excessive alloying can be suppressed even when the strip is being heated.In contrast, with the conventional direct heating method, only 6cl of alloying is required! If the time is long, the alloying speed will vary significantly depending on the zinc basis weight.Therefore, it is necessary to change the line speed depending on the zinc basis weight. Further, there is a problem that alloying progresses in a steel strip retention furnace where the furnace temperature is as high as 1000° C. or higher, and that alloying progresses excessively when the area weight is small. Therefore, the present invention can be said to be an extremely advantageous alloying treatment method for line operation.

Observation of the cross section of the alloy layer when alloyed under both conditions using a scanning electron microscope reveals that the conventional method (heating to 560°C, soaking for 5 seconds, treatment time 15 seconds) and the method of the present invention (laser heating) Compared to the alloy formed by heating to 690°C for 3 seconds, soaking for 3 seconds, and treatment time for 5 seconds), even if the method of the present invention is heat-treated for a short time, the alloy layer formed by conventional direct flame heating is It can be seen that a comparable alloy layer is formed.Next, FIG. 6 shows a line configuration when the method of the present invention is applied to electrolytic zinc oxide tin.

In the figure, (a) is the electrolytic cleaning and pickling tank, I# is the electroplating layer, gradient is the scrubber, and (b) is the phosphate treatment tank.This configuration is the same as the conventional one. In the method of the present invention, a dryer (to) and a laser heating device (11) are installed between the scrubber (2) and the phosphate treatment tank.
and a cooling device (32) to perform rapid heating. The laser heating device (31) is installed on the upper and lower surfaces of the IT steel strip .

In the case of electrogalvanized steel sheets, compared to hot-dip galvanized steel sheets, the plating layer does not contain Al, which suppresses alloying, and the alloying speed is slower. It's really fast. This method is advantageous for short-time in-line alloying, and the heating time limits the processing time, especially when electrogalvanized steel sheets require heating from room temperature, so laser heating can shorten the heating time. If the temperature exceeds 550°C for 3 to 4 seconds - '- sound,
L: Let's have some members.

It is possible to achieve alloying. This is the 4th E.
This shows that the present invention can be effectively applied to in-line alloying of electrogalvanized steel sheets. A specific example will be shown.

Fig. 7 shows the embodiment of this alloying apparatus as a laser-heated galvaneal furnace for a molten zinc line, and shows the following:
31) also has the same basic structure.

In the figure, CF) is a furnace body, and a pair of laser heating devices (L) are installed alternately facing each other from both sides of the steel strip (X). (OSC) is a laser oscillator. So 6
9. This is controlled by a computer (C). A radiation thermometer (0
) is provided, and this output is input to the computer (C) K via the amplifier (A).The computer (C) receives the feedback of the temperature signal from the thermometer (0), and calculates the temperature of the steel strip. Control the laser oscillation @ (OSC) so as to heat (X) to a predetermined set temperature. ・One or more laser heating devices (L) may be installed, and one unit of the above configuration may be used as needed. A plurality of units may be provided.

Note that the 8th WJ shows a sectional view taken along the line H-m in FIG. 7, and a laser heating device (L) heats the steel strip to a temperature of 1 yen by scanning an Fi laser beam in the width direction of the copper strip. In that case,
Regarding the laser beam irradiation plane, in order to effectively utilize the zero thermal energy of the laser beam, the area other than the laser beam incident area is covered with a reflecting mirror C.
M) is preferable. When applying the method of the present invention to an actual production line, an additional point that should be taken into account is the formation of a uniform alloy layer in the direction of the steel radius.Especially in wide areas. Assuming that 46 copper strips are to be processed.

The arrangement of the laser generating part is important. Figure 9 shows the arrangement of the laser generating part in the line. (AXB) is an example of the arrangement for a narrow steel strip.
(C) to (F) show examples of arrangement for wide steel strips. All of these methods aim to form a uniform and smooth alloy layer over the entire copper strip WJK, and either method can be adopted in the present Wi4. In the case of multiple light arrays, two or more rows can be used depending on the width of the steel strip. In FIG. 9, (4) is a laser for heating the top surface of the copper strip (tl) is a laser for heating the bottom surface of the copper strip.

Although there is no regulation in 41 regarding the type of laser emitting device, a COI laser is preferable as a high output laser emitting device.

As explained above, the method of the present invention performs alloying treatment by irradiating the plated surface with laser light and heat treatment for a short time, making it possible to shorten the vertical path length in the hot-dip galvanizing line.
Not only does it contribute to making the line more compact, but it is also effective in increasing the speed of sheet threading, making it extremely valuable from an industrial perspective8.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of a conventional molten galvanized line, Figure 2 is a diagram of a molten galvanized line in nine cases applying the method of the present invention, and Figure 3111 shows the relationship between alloying treatment time and copper strip temperature. Graph, Figure 4 is a graph showing the relationship between the holding time at the alloying temperature and the alloying temperature, and Figure * is the graph showing the relationship between the alloying treatment time and the alloying temperature in the direct-fired O-galvaneal furnace and the laser-heated galvaneal furnace. A graph showing the relationship between the alloying rate evaluated by the F content in the layer. Figure 6 is a line configuration diagram when the method of the present invention is applied to an electrolytic galvanizing line. Figure 7 is an example of an alloying device. Schematic diagram showing g
sm#: is a WJ diagram taken along the H-d line in FIG. 7, and FIG. 9 is an explanatory diagram of an example of the arrangement of the laser generating section. (Rotation)...V-ftJullk Manshiki 011 Rubanir F, (31)'...Laser heating device. Applicant: Nippon Doppan Co., Ltd. Inventor: Takashi Shimomura
Masa Abe Kima
Michihiro Hosoya Figure 3. Now customary traces (narrow) Figure 4 d4eAI-7: -488-TJ'rk' ((excerpt) No. 5
figure

Claims (1)

[Claims] Continuously galvanize the steel strip box, then irradiate the plated surface with laser light to rapidly heat it.
An alloying treatment method for galvanized steel sheet, characterized by subjecting it to a galvanizing treatment.