KR101435562B1 - Reverse roll cold rolling method of TWIP steel - Google Patents

Abstract

The present invention relates to a cold rolling method for TWIP steels, and more particularly, to a method for producing a thin plate type high strength tweed cold rolled steel sheet having excellent tensile strength and elongation using reverse rolling in a cold rolling technique.
The reverse roll cold rolling method of the tweed steel of the present invention includes a first step in which a pickled tweed steel coil is mounted on a left recoiler by a down coiler or a pay-off reel, A second step in which a tension of 50 to 300 KN is formed on a top portion of a tweed steel coil mounted on the left recoiler and then rolled up and a rolling roll having a width of 300 to 1,500 mm is used A third step of starting rolling of the tweed steel, and a fourth step of winding the rolled twiddle steel in a coil shape in a right recoiler and completing a one-time rolling process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse roll cold rolling method,

The present invention relates to a cold rolling method for TWIP steels, and more particularly, to a method for producing a thin plate type high strength tweed cold rolled steel sheet having excellent tensile strength and elongation using reverse rolling in a cold rolling technique.

Recently, environmental awareness has been raised, environmental regulations have been strengthened, and studies for improving the fuel efficiency of transportation equipment and vehicles have been continued. In order to improve the fuel efficiency, it is necessary to reduce the weight of the vehicle. To do so, it is necessary to reduce the thickness of the steel sheet used for the vehicle body. Since the safety is deteriorated by reducing the thickness of the steel sheet, the focus is on developing a high tensile steel having an excellent workability by increasing the strength and increasing the elongation. A typical steel grade is TWIP steel classified as AHSS (Advanced High Strength Steel), which is a high manganese steel showing an austenite single phase at room temperature.

In the TWIP steel, when the tandem rolling is used, the work hardening mechanism at the plastic deformation shows a Voce shape in which the strength is saturated after a certain strain, so that the hardening rates are different according to the rolling rate, In addition, due to the limited stand device, the process may be terminated without reaching the target thickness in the region where the work hardening proceeds sharply, and it is difficult to manufacture a thin plate twip steel sheet having a thickness of 1.0 mm or less.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above problems of the prior art, and it is an object of the present invention to produce a thin plate type twip cold rolled steel sheet having a high work hardening rate and excellent process and quality by using a reverse rolling apparatus.

The above object of the present invention is also achieved by a method of manufacturing a pickled steel of the present invention comprising a first step in which a pickled tweed steel coil is mounted on a left recoiler by a down coiler or a pay- A second step in which a tension of 50 to 300 KN is formed on a top portion of a twitch steel coil mounted on a left recoiler, and a second step in which the tweed steel is rolled using a rolling roll having a width of 300 to 1,500 mm. And a fourth step in which the rolled steel is wound on a Right Recoiler in the form of a coil to complete the one-time rolling process.

Therefore, the reverse roll cold rolling method of the tweed steel of the present invention is excellent in tensile strength and elongation, and has the effect of stably producing a high strength twipped cold rolled steel sheet having a thin thickness.

1 is a flow chart of a reverse roll cold rolling according to the present invention,
2 is a configuration diagram of a reverse roll cold rolling apparatus according to the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flow chart of a reverse roll cold rolling according to the present invention. As shown in FIG. 1, the cold rolling of a twip steel using a reverse roll uses a reverse rolling method, wherein C: 0.01 to 1.0 wt%, Si: 0.01 to 0.1 wt%, Mn: 15 to 25 wt% (TWIP) hot rolled steel containing 1.0 to 3.0% by weight of Al, 0.03% by weight or less of P, 0.03% by weight or less of S, and the balance of Fe and other unavoidable impurities, The coil 700 is mounted on a left recoiler 200 by a down coiler 100 or a pay-off reel 100 (S100) A tension of 50 to 300 KN is formed on a top portion of a coil of a tough steel 700 mounted on the main body 200 and wound up (S200). Thereafter, the rolling of the tweep steel 700 is started (S300) using the rolling roll 400 having a width of 300 to 1,500 mm, and the rolled twind steel 700 is wound on the right recoiler 600 Rolled in a coil form to complete the one-time rolling process (S400). Thereafter, the light recoiler 600 is rotated in the reverse direction to wind the tweed steel 700 wound in a coil shape using the rolling roll 400 (S500), and the tweep steel 700 rolled by the rolling roll 400 700 are wound in a coil form on the left recoiler 200 to complete the second rolling process (S600). The tweep steel 700 produced by the rolling process has a thickness of 0.3 to 2.5 mm and a width of 300 to 1,500 mm .

The process of picking the first tweep hot-rolled steel is as follows: Flattener - Pre-washer - Pickling zone - Rinse - Dry - X-ray gauge And pickling at a temperature of 70 to 90 ° C and a hydrochloric acid solution having a concentration of 2 to 25% by weight at a progressing rate of 30 to 70 m / min to remove impurities in the tweezed hot-rolled steel.

The flattening process smoothes the curved portion of the hot-rolled steel coil and generates fine cracks on the oxidized surface of the hot-rolled coil, thereby facilitating penetration of hydrochloric acid, thereby improving pickling.

The cleaning process is a process of spraying water before the introduction of the hydrochloric acid tank of the hot-rolled steel coil to remove dust and foreign substances to maintain the cleanliness of the hydrochloric acid tank. At this time, hot water of 40 to 70 ° C is sprayed on the hot- The preheating and the ability to remove foreign substances from hydrochloric acid are improved.

The acid treatment process goes through a total of three sections of hydrochloric acid tanks. The difference in the concentration of hydrochloric acid in each section tanks makes it easy to conduct acid pickling and to manage the hydrochloric acid solution. 1 section: 2 ~ 10%, 2 section: 5 ~ 15%, 3 section: 12 ~ 25% hydrochloric acid concentration. When the concentration decreases due to repeated pickling, the hydrochloric acid solution of each section is transferred to another section. The temperature of the hydrochloric acid solution is maintained at 70 to 90 ° C in all sections.

The pickling process is carried out by spraying hot water of 40 to 70 ° C on the surface of the hot-rolled steel coil through the hydrochloric acid tank to remove the acid

In the drying process, the hot-rolled steel coil is completely dried with hot air at 80 to 120 ° C., rust is easily generated when the moisture is left, and rinse marks are generated at the time of drying, so that the temperature of the hot wind and the moving speed of the coil are strictly controlled Control.

2 is a configuration diagram of a reverse roll cold rolling apparatus according to the present invention. As shown in Fig. 2, the rolling roll 400 is constituted by a work roll 401 and a backup roll 403, and may further comprise an intermediate roll 402, a support roll, and a support roll bearing. The rolling rolls 400 are composed of a maximum of 20 rolls and are symmetrical with one pair.

In the rolling process, the coil of the trough steel 700 passes through the rolling roll 400 and is wound on the light recoiler 600 in the form of a coil, and once the rolling is completed, the light recoiler 600 is wound in the reverse direction The tweep steel 700 is again passed through the rolling roll 500 and wound in the form of a coil on the left recoiler 200 to complete the rolling twice. Depending on the intended use of the steel sheet, the rolling is repeated a plurality of times by repeating the first rolling and the second rolling.

Further, at least one of the reduction amount, the reduction rate or the speed condition in the reverse rolling can be changed. In the rolling process, the rolling of 2,000 ~ 15,000 KN is integrated into the work roll 401, 5% or more and 40% or less in the case of performing the rolling, and when the rolling is performed a plurality of times, the reduction rate of the toffed steel 700 is at most 75% or less.

In the rolling process, it is possible to control the thickness of the steel sheet by using the profile gauge and the thickness gauge (300, 500). The final thickness of the tweed cold rolled steel sheet becomes 0.3 to 2.5 mm by controlling the thickness of the steel sheet.

The thickness of the steel sheet on the input side during the single rolling by controlling the thickness of the steel sheet is measured by the left thickness gauge 300 and the average of the thickness deviation is calculated by referring to the distance between the left thickness gauge 300 and the work roll 401 It is calculated automatically. The calculated deviation values refer to factors such as the material of the rolled steel sheet, the roll characteristics, and the thickness deviation, and control the thickness deviation using the automatic control method. The thickness variation width of the cold-rolled steel sheet on the output side during the first rolling is measured by the light thickness gauge 500 and the thickness variation is calculated by referring to the distance between the work roll 401 and the light thickness gauge 500 It is measured and automatically controlled by automatic control method referring to factors such as rolled material, roll characteristics, thickness deviation and the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, Various changes and modifications will be possible.

100: Down coiler or payoff reel 200: Left recoiler
300: Left thickness gauge 400: Rolling roll
401: work roll 402: intermediate roll
403: Backup Roll 500: Light Thickness Gauge
600: Light Recoiler 700: Tweed River

Claims (11)

The steel sheet contains 0.01 to 1.0 wt% of C, 0.01 to 0.1 wt% of Si, 15 to 25 wt% of Mn, 1.0 to 3.0 wt% of Al, 0.03 wt% or less of P and 0.03 wt% or less of S, In cold rolling of twip (TWIP) hot rolled steel containing Fe and other unavoidable impurities,
A pickled tin steel coil is mounted on a left recoiler by a down coiler or a pay-off reel;
A second step of forming a tension of 50 to 300 KN on a top portion of a tweed steel coil mounted on the left recoiler and winding the twisted coil;
A third step of starting the rolling of the tweep steel using a rolling roll having a width of 300 to 1,500 mm; And
The fourth step in which the rolled steel is rolled in a coil form in a right recoiler and the one-time rolling process is completed
Wherein the pickling process in the first step is carried out by pickling a hydrochloric acid solution having a temperature of 70 to 90 ° C and a concentration of 2 to 25% by weight at a proceeding speed of 30 to 70 m / min to remove foreign substances from the tweep steel A reverse roll cold rolling method of tweed steel characterized by:
The method according to claim 1,
A fifth step in which the right recoiler rotates in the reverse direction to roll the tweep steel wound in the coil shape using the rolling roll; And
A sixth step in which the twilled steel rolled by the rolling roll is wound on a left recoiler in the form of a coil to complete a second rolling process
Further comprising the steps of: (a) providing a cold rolled steel sheet;
The method according to claim 1,
Wherein the tweep steel has a thickness of 0.3 to 2.5 mm and a width of 300 to 1,500 mm.
delete The method according to claim 1,
The rolling roll in the third step is constituted by a work roll and a back-up roll and is composed of an intermediate roll, a support roll, a support roll wherein the cold rolled cold rolled steel sheet further comprises a bearing.
6. The method of claim 5,
Wherein said rolling rolls are composed of up to 20 rolls and are symmetrical in one pair.
Continuing to claim 5,
Wherein the work roll is rolled by integrating a rolling reduction of 2,000 to 15,000 KN.
The method according to claim 1,
In the third step, when the tweed steel coil passes through the rolling roll and is wound in a coil shape on a right recoiler, the rolling is completed once, and in the light recoiler, (left rollers) in the form of a coil, and the rolling is completed twice, and the rolling is repeated a plurality of times by repeating the first rolling and the second rolling according to the purpose of use of the steel sheet Reverse roll cold rolling method of tweed steel.
9. The method of claim 8,
Wherein the reversed rolling is capable of changing at least one of a reduction amount, a reduction rate, and a speed condition according to the purpose of use of the tweed steel during the reverse rolling.
10. The method of claim 9,
Wherein the rolling reduction is not less than 5% and not more than 40% when the rolling is performed once, and when the rolling is performed a plurality of times, the rolling reduction is not more than 75% Reverse roll cold rolling method of steel.
The method according to claim 1,
Wherein a thickness of the steel sheet is controllable by using a profile gauge and a thickness gauge in the third step and a final thickness of the twip cold rolled steel sheet is 0.3 to 2.5 mm by controlling the thickness of the steel sheet, Roll cold rolling method.

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