Sulfur additive for molten steel and method for producing resulfurized steel

Patent metadata

Field	Value
Publication number	US-11098384-B2
Application number	US-201716346060-A
Country	US
Kind code	B2
Filing date	Jun 13, 2017
Priority date	Nov 27, 2015
Publication date	Aug 24, 2021
Grant date	Aug 24, 2021

Abstract

A sulfur additive is added to molten steel. At that time, the yield of sulfur in the molten steel is stabilized and nozzle blockage at the time of continuous casting due to impurities is prevented. A sulfur additive used for molten steel which contains iron sulfide ore particles with a particle size of 5.0 to 37.5 mm in 85 mass % or more with respect to the total mass % of the sulfur additive is used to produce Al deoxidized resulfurized steel containing S: 0.012 to 0.100 mass %.

First claim

The invention claimed is:

1. A sulfur additive used for molten steel, wherein the sulfur additive contains iron sulfide ore particles having a particle size of 9.5 to 31.5 mm of 85% or more and oxygen concentration of 9 mass % or less by mass % based on the total mass % thereof.

2. A method for producing resulfurized steel comprising a sulfur adding step of adding the sulfur additive according to claim 1 to Al-deoxidized molten steel, wherein
the method for producing the resulfurized steel smelts resulfurized steel comprising, by mass %,
C: 0.07 to 1.20%,
Si: over 0 to 1.00%,
Mn: over 0 to 2.50%,
N: over 0 to 0.02%
S: 0.012 to 0.100%, and
Al: 0.015 to 0.100,
P: limited to 0.10% or less, and
a balance of iron and unavoidable impurities.

3. The method for producing resulfurized steel according to claim 2 , wherein the resulfurized steel further contains, by mass %, one or more elements selected from
Cu: 2.00% or less,
Ni: 2.00% or less,
Cr: 2.00% or less,
Mo: 2.00% or less,
Nb: 0.25% or less,
V: 0.25% or less,
Ti: 0.30% or less, and
B: 0.005% or less.

Assignees

• Nippon Steel Corp

Inventors

• Hasegawa Hajime
• Kudo Susumu
• Matsushima Mitsuhiro
• Sekiuchi Tetsuro

Classifications

• C22C38/001 Primary

  containing N · CPC title

• C22C38/60 Primary

  containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur · CPC title

• C22C38/00

  Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00) · CPC title

• C21C7/10

  Handling in a vacuum · CPC title

• C22C38/06

  containing aluminium · CPC title