# US 12,766,591 B2 · Steel continuous casting method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,766,591 B2 - Document ID: US12766591B2 - Status: Granted - Kind: B2 - Application number: 18/730,104 - Filed: 2023-03-23 - Published: 2025-05-08 - Granted: 2026-10-20 - Earliest claimed: 2022-03-28 - Assignees: Jfe Steel Corporation - Applicants: Jfe Steel Corporation - Inventors: Norichika Aramaki; Shuhei Irie; Akitoshi Matsui; Hirokazu Sugihara; Yusuke Nojima - Web page: https://patentgrep.com/patent/US12766591B2 ## CPC - B22D 11/1246: {Nozzles; Spray heads} - B22D 11/22: for cooling cast stock or mould - 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 A steel continuous casting method effectively reducing center segregation occurring inside a cast piece includes cooling of a cast piece performed with a water volume density per surface area of the cast piece in a first section set within a range of 50 to 2000 L/(m2×min) or lower. The first section is a range along a cast piece withdrawing direction in a continuous casting machine, from a start point at which an average value of a solid phase ratio along a thickness direction at a final solidified part in a cast piece width direction is 0.8 or lower to an end point at which the average value of the solid phase ratio along the thickness direction at the final solidified part in the cast piece width direction is higher than the solid phase ratio at the start point but not higher than 1.0. ## Claims ### Claim 1 A steel continuous casting method comprising: cooling of a cast piece is performed at a water volume density per surface area of the cast piece in a first section set within a range of 50 to 2000 L/(m2×min), the first section being a range along a cast piece withdrawing direction in a continuous casting machine, from a start point at which an average value of a solid phase ratio along a thickness direction at a position of a width-direction solidified part at which the solid phase ratio is the lowest in a cast piece width direction is 0.8 or lower to an end point at which the average value of the solid phase ratio along the thickness direction at the position of the width-direction solidified part at which the solid phase ratio is the lowest in the cast piece width direction is higher than the solid phase ratio at the start point but not higher than 1.0. ### Claim 2 (depends on 1) The steel continuous casting method according to claim 1, wherein cooling of the cast piece is performed with the water volume density per surface area of the cast piece in a second section set within a range of 50 to 300 L/(m2×min), the second section being a section which is located downstream of the first section and in which the average value of the solid phase ratio in the width direction at the end point is 1.0 or lower. ### Claim 3 (depends on 2) The steel continuous casting method according to claim 2, wherein at least after the first section ends and while the second section is passed through, casting is performed so as to maintain a nucleate boiling state in which a surface temperature of the cast piece is 200° C. or lower, and a temperature gradient near a center in a thickness of the cast piece at a last solidification stage is set to 1.7 to 3.5 K/mm. ### Claim 4 (depends on 3) The steel continuous casting method according to claim 3, wherein the first section and the second section are each set inside a region restricted to a horizontal segment or a vertical segment in the continuous casting machine. ### Claim 5 (depends on 4) The steel continuous casting method according to claim 4, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 6 (depends on 3) The steel continuous casting method according to claim 3, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 7 (depends on 2) The steel continuous casting method according to claim 2, wherein the first section and the second section are each set inside a region restricted to a horizontal segment or a vertical segment in the continuous casting machine. ### Claim 8 (depends on 7) The steel continuous casting method according to claim 7, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 9 (depends on 2) The steel continuous casting method according to claim 2, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 10 (depends on 1) The steel continuous casting method according to claim 1, wherein at least after the first section ends and while the second section is passed through, casting is performed so as to maintain a nucleate boiling state in which a surface temperature of the cast piece is 200° C. or lower, and a temperature gradient near a center in a thickness of the cast piece at a last solidification stage is set to 1.7 to 3.5 K/mm. ### Claim 11 (depends on 10) The steel continuous casting method according to claim 10, wherein the first section and the second section are each set inside a region restricted to a horizontal segment or a vertical segment in the continuous casting machine. ### Claim 12 (depends on 11) The steel continuous casting method according to claim 11, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 13 (depends on 10) The steel continuous casting method according to claim 10, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 14 (depends on 1) The steel continuous casting method according to claim 1, wherein the first section and the second section are each set inside a region restricted to a horizontal segment or a vertical segment in the continuous casting machine. ### Claim 15 (depends on 14) The steel continuous casting method according to claim 14, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 16 (depends on 1) The steel continuous casting method according to claim 1, wherein, in the first section and the second section, soft reduction is applied, and the cast piece is reduced from long-side surfaces at a reduction rate of 0.3 to 2.0 mm/min. ### Claim 17 (depends on 1) The steel continuous casting method according to claim 1, wherein a roll gap of a plurality of pairs of cast piece support rolls is incrementally increased toward a downstream side in a casting direction so as to bulge long-side surfaces of the cast piece by a total bulging amount of 2 to 20 mm, and then the roll gap of the plurality of pairs of cast piece support rolls is incrementally decreased toward the downstream side in the casting direction so as to softly reduce the cast piece.