Filament for high strength steel cord

Patent metadata

Field	Value
Publication number	US-10156001-B2
Application number	US-201515305522-A
Country	US
Kind code	B2
Filing date	Apr 23, 2015
Priority date	Apr 24, 2014
Publication date	Dec 18, 2018
Grant date	Dec 18, 2018

Abstract

A filament for a high strength steel cord has a wire diameter R of 0.1 mm to 0.4 mm, and includes, in a chemical composition, by mass %: C: 0.70% to 1.20%; Si: 0.15% to 0.60%; Mn: 0.10% to 1.00%; N: 0.0010% to 0.0050%; Al: more than 0% and 0.0100% or less; and a remainder of Fe and impurities, in which a surface part and a central part are included, a thickness of the surface part is 0.01×R to 0.10×R, the central part includes a pearlite structure in a proportion of 95% to 100% by area %, a C content of the surface part is 40% to 95% of a C content of the central part, and a ratio of a thickness of a lamellar cementite at a center of the thickness of the surface part to a thickness of a lamellar cementite in the central part is 95% or less, whereby high strength and workability can be achieved and cracking or the like caused by a delamination phenomenon can be prevented.

First claim

The invention claimed is:

1. A filament for a high strength steel cord, which has a wire diameter R of 0.1 mm to 0.4 mm, comprising, in a chemical composition, by mass %:
C: 0.70% to 1.20%;
Si: 0.15% to 0.60%;
Mn: 0.10% to 1.00%;
N: 0.0010% to 0.0050%;
Al: more than 0% and 0.0100% or less; and
a remainder of Fe and impurities,
wherein a surface part and a central part are included, the surface part covers the central part,
a thickness of the surface part is 0.01×R to 0.10×R,
the central part includes a pearlite structure in a proportion of 95% to 100% by area %,
a C content of the surface part is 40% to 95% of a C content of the central part, and
a ratio of a thickness of a lamellar cementite at a center of the thickness of the surface part to a thickness of a lamellar cementite in the central part is 95% or less.

2. The filament for a high strength steel cord according to claim 1 , further comprising, in the chemical composition, by mass %,
one or two or more of
Ti: more than 0% and 0.1000% or less,
Cr: more than 0% and 0.5000% or less,
Co: more than 0% and 0.5000% or less,
V: more than 0% and 0.5000% or less,
Cu: more than 0% and 0.2000% or less,
Nb: more than 0% and 0.1000% or less,
Mo: more than 0% and 0.2000% or less,
W: more than 0% and 0.200% or less,
B: more than 0% and 0.0030% or less,
REM: more than 0% and 0.0050% or less,
Ca: more than 0.0005% and 0.0050% or less,
Mg: more than 0.0005% and 0.0050% or less, and
Zr: more than 0.0005% and 0.0100% or less.

Assignees

• Nippon Steel & Sumitomo Metal Corp

Inventors

• Hirakami Daisuke
• Okonogi Makoto

Classifications

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C22C38/00

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

• C22C38/02

  containing silicon · CPC title

• C21D9/52 Primary

  for wires; for strips {; for rods of unlimited length} · CPC title

• C22C38/06

  containing aluminium · CPC title