# US 11,077,492 B2 · Continuous steel casting method

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- Number: US 11,077,492 B2
- Document ID: US11077492B2
- Status: Granted
- Kind: B2
- Application number: 16/975,793
- Filed: 2019-02-25
- Published: 2020-12-31
- Granted: 2021-08-03
- Earliest claimed: 2018-03-02
- Assignees: Jfe Steel Corporation
- Applicants: JFE Steel Corporation
- Inventors: Keigo Toishi; Yutaka Awajiya; Norichika Aramaki; Naoki Kikuchi
- Web page: https://patentgrep.com/patent/US11077492B2

## CPC

- B22D 11/1282: {Vertical casting and curving the cast stock to the horizontal}
- B22D 11/1287: {Rolls; Lubricating, cooling or heating rolls while in use}
- B22D 11/041: for vertical casting (B22D11/043, B22D11/049 - B22D11/059 take precedence)
- B22D 11/1206: {for plastic shaping of strands (rolling mills B21B1/46)}
- B22D 11/16: Controlling or regulating processes or operations
- B22D 11/207: {responsive to thickness of solidified shell}
- B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22)

## Abstract

In the continuous steel casting method of the present invention, a gap between strand support rolls with a strand in a rectangular shape interposed therebetween is increased toward a downstream side in a casting direction to thereby bulge the strand having an unsolidified layer thereinside such that the thickness between long-side surfaces of the strand increases within the range of 0.1% or more and 10% or less of the thickness of the strand inside a mold. A portion of the strand in which the solid phase fraction in a central portion of the strand is within the range of 0.2 or more and less than 0.9 satisfies a prescribed total rolling reduction and a prescribed reduction gradient, and a portion of the strand in which the solid phase fraction is within the range of 0.9 or more satisfies a prescribed total rolling reduction and a prescribed reduction gradient.

## Claims

### Claim 1

A continuous steel casting method, wherein, during continuous casting of steel, a gap between strand support rolls facing each other with a strand in a rectangular shape interposed therebetween is increased toward a downstream side in a casting direction to thereby bulge the strand having an unsolidified layer thereinside such that a thickness between long-side surfaces of the strand increases within the range of 0.1% or more and 10% or less of the thickness of the strand inside a mold, and wherein, when the long-side surfaces of the bulged strand are rolled by a plurality of guide rolls,
a total rolling reduction and a reduction gradient satisfy formulas (1) and (2) below when a solid phase fraction in a central portion of the strand is within the range of 0.2 or more and less than 0.9, and the total rolling reduction and the reduction gradient satisfy formulas (3) and (4) below when the solid phase fraction in the central portion of the strand is within the range of 0.9 or more:
0.5≤Rt1/D0≤1.0, (1)
0.5≤Rg1≤3.0, (2)
0.2≤Rt2/D0≤1.0, (3)
0.1≤Rg2≤1.5, (4)
where Rt1: the total rolling reduction (mm) of the strand when the solid phase fraction is within the range of 0.2 or more and less than 0.9, D0: the amount of bulging (mm) of the strand, Rg1: the reduction gradient (mm/m) of the strand when the solid phase fraction is within the range of 0.2 or more and less than 0.9, Rt2: the total rolling reduction (mm) of the strand when the solid phase fraction is within the range of 0.9 or more, and Rg2: the reduction gradient (mm/m) of the strand when the solid phase fraction is within the range of 0.9 or more.