Continuous casting mold and method for continuous casting of steel

Patent metadata

Field	Value
Publication number	US-10792729-B2
Application number	US-201314410394-A
Country	US
Kind code	B2
Filing date	Jun 11, 2013
Priority date	Jun 27, 2012
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

A continuous casting mold according to the present invention has plural separate portions filled with a metal of low thermal conductivity formed by filling a metal having a thermal conductivity of 30% or less of that of copper into circular concave grooves having a diameter of 2 to 20 mm which are formed in the region of the inner wall surface of the copper mold from an arbitrary position higher than a meniscus to a position 20 mm or more lower than the meniscus, in which the filling thickness of the metal in the portions filled with the metal of low thermal conductivity is equal to or less than the depth of the circular concave grooves and satisfies the relationship with the diameter of the portions filled with the metal of low thermal conductivity expressed by expression (1) below:

0.5≤ H≤d   (1).

First claim

The invention claimed is:

1. A continuous casting copper mold, the copper mold comprising a plurality of separate portions filled with a metal of low thermal conductivity, the separate portions being formed by filling the metal of low thermal conductivity into circular concave grooves and/or quasi-circular concave grooves, the metal of low thermal conductivity having a thermal conductivity that is 30% or less than the copper of the copper mold at a temperature after the mold has been solidified and cooled completely in manufacturing the mold, the circular concave grooves having a diameter from 2 mm to 20 mm and the quasi-circular concave grooves having an equivalent circle diameter from 2 mm to 20 mm, and the circular concave grooves and the quasi-circular concave grooves being formed in a region on an inner wall surface of the copper mold defined by (i) a position higher than a meniscus and (ii) a position 20 mm or more lower than the meniscus,
wherein a filling thickness of the metal of low thermal conductivity in the separate portions is equal to or less than a depth of the circular concave grooves or the quasi-circular concave grooves, and satisfies relationship (1):
0.5≤ H≤d   (1),

where H represents the filling thickness (mm) of the metal of low thermal conductivity and d represents the diameter (mm) or equivalent circle diameter (mm) of the separate portions,
the inner wall surface of the copper mold is coated with a Ni-alloy layer having a thickness of 2.0 mm or less,
the separate portions filled with the metal of low thermal conductivity are covered with the Ni-alloy layer,
the plurality of separate portions are formed throughout the region on the inner wall surface, and
a distance in a casting direction between a lower edge of the region and a lower edge of the copper mold satisfies relationship (2):
L≥Vc× 100  (2),

where L represents the distance (mm) between the lower edge of the region and the lower edge of the copper mold and Vc represents a cast piece drawing speed (m/min) when casting is performed.

2. The continuous casting copper mold according to claim 1 , wherein a closest distance between immediately adjacent portions of the plurality of separate portions satisfies relationship (3):
P≥ 0.25× d   (3),

where P represents the closest distance (mm) between the immediately adjacent portions and d represents the diameter (mm) or equivalent circle diameter (mm) of the separate portions.

3. The continuous casting copper mold according to claim 2 , wherein the closest distance between the immediately adjacent portions varies among the plurality of separate portions in width direction and/or casting direction.

4. The continuous casting copper mold according to claim 1 , wherein the separate portions constitute 10% or more of the area of the region on the inner wall surface of the copper mold.

5. The continuous casting copper mold according to claim 1 , wherein diameters or equivalent circle diameters of the separate portions vary among the plurality of separate portions in a width direction or casting direction within the range from 2 mm to 20 mm.

6. The continuous casting copper mold according to claim 1 , wherein thicknesses of the separate portions vary among the plurality of separate portions in width direction or casting direction within the range satisfying relationship (1).

7. A method for continuously casting steel, the method comprising using the continuous casting copper mold according to claim 1 and continuously casting molten steel by injecting the molten steel in a tundish into the continuous casting copper mold.

8. The method for continuously casting steel according to claim 7 , wherein the region in which the separate portions are formed throughout extends from a position lower than the meniscus to a distance from the meniscus equal to or more than a distance (R) derived using relationship (4) depending on a cast piece drawing speed when casting is performed, the cast piece drawing speed when casting is performed being 0.6 m/min or more and a mold powder having a crystallization temperature of 1100° C. or lower and a basicity ((CaO by mass %)/(SiO 2 by mass %)) of 0.5 or more and 1.2 or less being used:
R= 2× Vc× 1000/60  (4),

where R represents the distance (mm) from the meniscus and Vc represents the cast piece drawing speed (m/min) when casting is performed.

9. The method for continuously casting steel according to claim 7 , wherein the molten steel of a medium-carbon steel having a C content in the range from 0.08 mass % to 0.17 mass % is continuously cast at a cast piece drawing speed of 1.5 m/min or more to form a cast slab having a thickness of 200 mm or more.

10. The continuous casting copper mold according to claim 1 , wherein the separate portions are formed by filling the metal of low thermal conductivity into the circular concave grooves and/or quasi-circular concave grooves with a plating means or thermal spraying means.

11. The continuous casting copper mold according to claim 1 , wherein the copper of the copper mold has a thermal conductivity of 380 W/(m·K).

Assignees

• Jfe Steel Corp

Inventors

• Nabesima Seiji
• Iwata Naomichi
• Aramaki Norichika
• Miki Yuji

Classifications

• B22D11/122

  using magnetic fields · CPC title

• B22D11/001

  of specific alloys · CPC title

• B22D11/059 Primary

  Mould materials or platings · CPC title

• B22D11/04 Primary

  into open-ended moulds (B22D11/06, B22D11/07 take precedence; plants for continuous casting, e.g. for upwardly drawing the strand B22D11/14) · CPC title

• B22D11/0406 Primary

  Moulds with special profile · CPC title