JPH09174200A - Continuous casting mold - Google Patents

Abstract

(57) Abstract: The present invention provides a continuous casting mold capable of reliably preventing vertical cracks by uniformly cooling (heat removal) in the width direction of a cast piece. A casting mold for continuous casting in which the distance between the cooling groove tip and the molten steel contact surface at the center in the width direction of the mold is shorter than the distance between the cooling groove tip and the molten steel contact surface at both ends.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting mold.

[0002]

2. Description of the Related Art In continuous casting, as shown in FIGS. 2 and 3, the tips of cooling grooves 4 and molten steel contact surfaces 5 are formed at equal intervals on the long sides 2, 2a and the short sides 3, 3a of a mold 1. do it,
While cooling the mold 1 by supplying cooling water to this cooling groove, the molten steel is continuously cast, but the amount of heat removed (cooling) in the widthwise central portion of the slab becomes larger than that of both ends during casting, This may cause vertical cracking of the slab. In order to make such heat removal amount uniform, it is possible to control the heat removal amount in the width direction of the slab by applying a surface treatment material to the molten steel contact surface on the long side of the mold.
It is disclosed in Japanese Patent Publication No. 8-148053. Further, Japanese Patent Application Laid-Open No. 58-61951 discloses heat removal from a cast piece by obliquely forming a cooling groove on the long side of the mold.

[0003]

In the former heat removal method as described above, since the surface treatment material is worn or peeled off, it is necessary to apply it regularly. Therefore, the coating work is added to the maintenance of the mold, and the maintenance takes a long time, which is labor-saving and costly. Further, in the latter mold, the intervals of the cooling grooves become dense and there is no heat removal difference between the cooling grooves, but heat removal control of the entire length in the long side width direction of the mold is not possible, and vertical cracking of the slab, etc. There is a problem that it cannot be prevented. The present invention has been made in order to advantageously solve such a problem, to ensure the heat removal control of the mold long side width direction, to provide a mold that can prevent vertical cracking of the slab The purpose is to do.

[0004]

The feature of the present invention resides in that the distance between the cooling groove tip and the molten steel contact surface at both ends is shorter than the distance between the cooling groove tip and the molten steel contact surface at the center in the width direction of the mold. The continuous casting mold is characterized in that it is formed at a distance.

BEST MODE FOR CARRYING OUT THE INVENTION

In the present invention, as described above, the distance between the cooling groove tips at both ends and the molten steel contact surface is set to be shorter than the distance between the cooling groove tips at the central portion in the width direction and the molten steel contact surface. The distance between the center of the cooling groove and the molten steel contact surface is longer than the distance between the ends of the cooling groove and the molten steel contact surface at both ends in the width direction. Therefore, the thermal resistance of the central portion in the width direction increases,
Slow cooling of molten steel (cast slab) in the widthwise central part (gradual heat removal)
As a result, the molten steel (slab) can be uniformly removed (cooled) over the entire length in the width direction. Because of this, powder (lubricant)
Flow between the mold and molten steel (cast slab) is uniform over the entire length in the width direction, and heat removal (cooling) of the molten steel (cast slab) at the center in the width direction
It is possible to reliably prevent vertical cracking of the cast slab, which is considered to be caused by a local contraction action or the like due to the increase in the size of the slab.

The difference between the molten steel contact surface distance between the long side widthwise central cooling groove tip and the cooling groove tips at both ends is different depending on the molten steel composition and the like, but is, for example, C: 0.00.
1 to 0.05%, Mn: 0.1 to 0.5%, Si: 0.
01% or less, P: 0.05% or less, S: 0.05% or less, SolAl: 0.005-0.08%, low carbon steel consisting of the remaining Fe and other impurities, molten steel temperature injected 1540-
If the thickness of the long side of the mold is 50 to 60 mm at 1580 ° C,
The distance between the tip of the cooling groove and the molten steel contact surface at the center of the long side width direction is set to be 7 to 15 mm shorter than the distance between the ends, and the width direction of the molten steel (cast slab) is reliably ensured under normal cooling conditions. Uniform cooling (heat removal) can prevent vertical cracks and the like.

[0007]

EXAMPLES Next, examples of the present invention will be described. In Fig. 1, the distance B between the cooling groove 4 tip and the molten steel contact surface 5 at the center A in the width direction of the long side 2a of the mold 1 is shorter than the distance B between the cooling groove 4 tip and the molten steel contact surface 5 at both ends C and D. To form. The other long side is similarly configured.

Next, an operation example of continuous casting using the mold according to the present invention will be described. 1) Mold long side thickness: 56 mm, cooling groove width: 5 mm, cooling groove interval: 30 mm, long side width direction central portion length: 500 mm,
Long side width direction both ends length: 1200mm (one side 600m
m), molten steel contact surface distance between the tip of the cooling groove in the widthwise central portion of the long side and 30 mm. Short side thickness: 56 mm, cooling groove width: 5 m
m, cooling groove interval: 30 mm, distance between short side cooling groove tips and molten steel contact surface: all cooling grooves 20 mm. 2) Operating conditions (1) Slab thickness: 245 mm, width: 1500 mm. (2) Molten steel composition (%): C: 0.12, Mn: 0.4,
Si: 0.25, P: 0.02, S: 0.02, Sol
Al: 0.03, remaining Fe and other impurities. (3) Molten steel pouring temperature: 1550 ° C. (4) Casting speed: 1.3 m / min. (5) Supply amount of mold cooling water (normal temperature): 4000 to 4500
l / min. (6) Mold depth: 900 mm. As described above, 1000 t of cast slab was cast by continuous casting, and the length of vertical cracks in the cast slab was reduced to 1/10, resulting in an excellent effect.

[0009]

According to the present invention, the cooling (heat removal) in the width direction of the slab can be uniformly controlled, the vertical cracks of the slab are reliably prevented from occurring, and the quality is improved. The yield can be increased. In addition, cooling (heat removal) is controlled in the width direction of the slab by adjusting (forming) the distance between the molten metal contact surface and the tip of the cooling groove of the mold, which can be formed at the time of mold production and requires almost no cost. And so on.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of the present invention.

FIG. 2 is a plan view of a continuous casting mold.

FIG. 3 is a plan view of a continuous casting mold.

[Explanation of symbols]

 1 mold 2 long side of mold 2a long side of mold 3 short side of mold 3a short side of mold 4 cooling groove 5 molten steel contact surface of mold

Claims (1)

[Claims] 1. A continuous casting mold characterized in that the distance between the cooling groove tip and the molten steel contact surface at the central portion in the width direction of the long side is shorter than the distance between the cooling groove tip and the molten steel contact surface at both ends. .