# US 9,751,126 B2 · Method for controlling surface quality of ultra-low carbon steel slab

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 9,751,126 B2
- Document ID: US9751126B2
- Status: Granted
- Kind: B2
- Application number: 14/770,746
- Filed: 2013-12-26
- Published: 2016-01-14
- Granted: 2017-09-05
- Earliest claimed: 2013-02-27
- Assignees: Hyundai Steel Company
- Applicants: Hyundai Steel Company
- Inventors: Hae Young Seo; Suk Hyun Yoo; Hyo Joong Kwon; Yeong Joo Do; Kae Young Lee; Ju Tae Choi
- Web page: https://patentgrep.com/patent/US9751126B2

## CPC

- B22D 11/16: Controlling or regulating processes or operations
- B22D 11/001: {of specific alloys}
- 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

The present invention provides a method for controlling the surface quality of an ultra-low carbon steel slab, the method comprising the steps of: measuring the phosphorus (P) concentration, sulfur (S) concentration and superheating degree of a molten steel which is introduced into a mould in a continuous casting process for producing the ultra-low carbon steel slab, the width of the mould, and the casting speed of the slab; and calculating the depth of a hook which is formed when the molten steel is solidified into the slab, based on the measured width of the mould, the measured phosphorus (P) concentration, sulfur (S) concentration and superheating degree of the molten steel, and the measured casting speed of the slab.

## Claims

### Claim 1

A method for controlling a surface quality of an ultra-low carbon steel slab, the method comprising the steps of:
measuring of a phosphorus (P) concentration of a molten steel which is introduced into a mold in a continuous casting process for producing the ultra-low carbon steel slab,
measuring of a sulfur (S) concentration of the molten steel,
measuring a superheating temperature of the molten steel,
measuring a width of the mold, and measuring a casting speed of the ultra-low carbon steel slab; and calculating a depth of a hook which is formed when the molten steel is solidified into the slab, as a function of the measured width of the mold, the measured phosphorus (P) concentration of the molten steel, the measured sulfur (S) concentration of the molten steel, the measured superheating degree of the molten steel, and the measured casting speed of the slab, calculating the depth of the hook utilizing the following equation:
Y=A0ln(A1×A4/(A2×A3×A5))+B
wherein A1 is the width of the mold; A2 is the superheating temperature; A3 is the casting speed; A4 is the sulfur (S) concentration; A5 is the phosphorus (P) concentration; Y is the depth of the hook; A0 is a coefficient; and B is a constant, wherein 0.51≦A0≦0.94; and −0.21≦B≦0.11; and changing the casting speed to control the depth of the hook, when the calculated depth of the hook is deeper than a preset depth of the hook.

### Claim 2

A method for controlling a surface quality of an ultra-low carbon steel slab, the method comprising the steps of:
measuring of a phosphorus (P) concentration of a molten steel which is introduced into a mold in a continuous casting process for producing the ultra-low carbon steel slab,
measuring of a sulfur (S) concentration of the molten steel,
measuring a superheating temperature of the molten steel,
measuring a width of the mold, and measuring a casting speed of the ultra-low carbon steel slab; and calculating a depth of a hook which is formed when the molten steel is solidified into the slab, as a function of the measured width of the mold, the measured phosphorus (P) concentration of the molten steel, the measured sulfur (S) concentration of the molten steel, the measured superheating degree of the molten steel, and the measured casting speed of the slab, calculating the depth of the hook utilizing the following equation:
Y=A0ln(A1×A4/(A2×A3×A5))+B
wherein A1 is the width of the mold; A2 is the superheating temperature; A3 is the casting speed; A4 is the sulfur (S) concentration; A5 is the phosphorus (P) concentration; Y is the depth of the hook; A0 is a coefficient; and B is a constant, wherein 0.51≦A0≦0.94; and −0.21≦B≦0.11; and changing the superheating degree to control the depth of the hook, when the calculated depth of the hook is deeper than a preset depth of the hook.

### Claim 3

A method for controlling a surface quality of an ultra-low carbon steel slab, the method comprising the steps of:
measuring of a phosphorus (P) concentration of a molten steel which is introduced into a mold in a continuous casting process for producing the ultra-low carbon steel slab,
measuring of a sulfur (S) concentration of the molten steel,
measuring a superheating temperature of the molten steel,
measuring a width of the mold, and measuring a casting speed of the ultra-low carbon steel slab; and calculating a depth of a hook which is formed when the molten steel is solidified into the slab, as a function of the measured width of the mold, the measured phosphorus (P) concentration of the molten steel, the measured sulfur (S) concentration of the molten steel, the measured superheating degree of the molten steel, and the measured casting speed of the slab, calculating the depth of the hook utilizing the following equation:
Y=A0ln(A1×A4/(A2×A3×A5))+B
wherein A1 is the width of the mold; A2 is the superheating temperature; A3 is the casting speed; A4 is the sulfur (S) concentration; A5 is the phosphorus (P) concentration; Y is the depth of the hook; A0 is a coefficient; and B is a constant, wherein 0.51≦A0≦0.94; and −0.21≦B≦0.11; and
scarfing a surface of the ultra-low carbon steel slab as a function of the calculated depth of the hook.

### Claim 4 (depends on 1)

The method of claim 1, wherein the ultra-low carbon steel slab has a carbon content of 0.01 parts by weight or less based on 100 parts by weight of the ultra-low carbon steel slab.

### Claim 5 (depends on 2)

The method of claim 2, wherein the ultra-low carbon steel slab has a carbon content of 0.01 parts by weight or less based on 100 parts by weight of the ultra-low carbon steel slab.

### Claim 6 (depends on 3)

The method of claim 3, wherein the ultra-low carbon steel slab has a carbon content of 0.01 parts by weight or less based on 100 parts by weight of the ultra-low carbon steel slab.