Steel wire for drawing

• US 10,329,646 B2
• Filed: 08/14/2015
• Issued: 06/25/2019
• Est. Priority Date: 08/15/2014
• Status: Active Grant

• Current Assignee: Nippon Steel Corporation
• Original Assignee: Nippon Steel & Sumitomo Metal Corporation (Nippon Steel Corporation)
• Inventors: Daito, Yoshihiro, Kodama, Junichi, Sakamoto, Masashi
• Primary Examiner(s): Walck, Brian D
• Application Number:
  US15/503,487
• Publication Number:
  US 20170241000A1
• Time in Patent Office: 1,411 Days
• Field of Search: 148320
• CPC Class Codes: C21D 2211/009 Pearlite
• CPC Class Codes: C21D 8/06 during manufacturing of rods or wires
• CPC Class Codes: C21D 9/525 for wire, for rods C21D9/54 takes precedence
• CPC Class Codes: C22C 38/00 Ferrous alloys, e.g. steel alloys cast-iron alloys C22C37/00
• CPC Class Codes: C22C 38/001 containing N
• CPC Class Codes: C22C 38/002 containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
• CPC Class Codes: C22C 38/02 containing silicon
• CPC Class Codes: C22C 38/04 containing manganese
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/18 containing chromium
• CPC Class Codes: C22C 38/22 with molybdenum or tungsten
• CPC Class Codes: C22C 38/32 with boron

Abstract

A steel wire for drawing includes, as a chemical composition, by mass %: C: 0.9% to 1.2%, Si: 0.1% to 1.0%, Mn: 0.2% to 1.0%, and Cr: 0.2% to 0.6%, limits Al, N, P, and S to be predetermined ranges, and includes one or more selected from the group consisting of Mo: 0% to 0.20%, and B: 0% to 0.0030%, a remainder of Fe and impurities; in which a metallographic structure includes pearlite, a volume fraction of the pearlite is 95% or higher, an average lamellar spacing of the pearlite is 50 nm to 75 nm, an average length of cementite in the pearlite is 2.0 μm to 5.0 μm, and a ratio of the number of grains of cementite with a length of 0.5 μm or smaller to the cementite in the pearlite is 20% or lower.

Claims

1. A steel wire for drawing comprising, as a chemical composition, by mass %,

C:

0.9% to 1.2%,

Si;

0.1% to 1.0%,

Mn;

0.2% to 1.0%,

Cr;

0.2% to 0.6%,

Al;

limited to 0.002% or less,

N;

limited to 0.007% or less,

P;

limited to 0.02% or less,

S;

limited to 0.01% or less, and

one or more selected from the group consisting of

Mo;

0% to 0.20%, and

B;

0% to 0.0030%, and

a remainder of Fe and impurities,

wherein a metallographic structure includes a pearlite, and a volume fraction of the pearlite is 95% or higher,

an average lamellar spacing of the pearlite is 50 nm to 75 nm,

an average length of cementite in the pearlite is 2.0 μ

m to 5.0 μ

m, and

a ratio of the number of grains of cementite with a length of 0.5 μ

m or smaller to the cementite in the pearlite is 20% or lower.

2. The steel wire for drawing according to claim 1, comprising, as the chemical composition, by mass %,

one or more selected from the group consisting of

Mo:

0.02% to 0.20%, and

B;

0.0005% to 0.0030%.