IP Library Granted Patent US 10,487,379
Granted Patent B2
US 10,487,379 · App. 15/329,455 · Granted Nov 26, 2019

High-carbon steel wire rod with excellent wire drawability

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Quick Facts
Patent No.
US 10,487,379
App. No.
15/329,455
Granted
Nov 26, 2019
Kind
B2
Abstract

Provided is a high-carbon steel wire rod with excellent wire drawability, containing predetermined chemical components and the balance: Fe and impurities. In a cross-section perpendicular to a longitudinal direction, an area fraction of pearlite is equal to or more than 95% and equal to or less than 100%, an average block size of the pearlite is 10 μm to 30 μm and standard deviation of block size is 20 μm or less, and when Ceq.=C (%)+Si (%)/24+Mn (%)/6, a tensile strength is equal to or more than 760×Ceq.+255 MPa and equal to or less than 760×Ceq.+325 MPa, reduction of area in a tensile test is −65×Ceq.+96(%) or more, and standard deviation of the reduction of area is 6% or less.

Claims (27)

1. A high-carbon steel wire rod with excellent wire drawability, comprising chemical components of, in mass %,

C: 0.70% to 1.20%,

Si: 0.10% to 1.2%,

Mn: 0.10% to 1.0%,

P: 0.001% to 0.012%,

S: 0.001% to 0.010%,

N: 0.0010% to 0.0050%, and

the balance: Fe and impurities,

wherein in a cross-section perpendicular to a longitudinal direction, an area fraction of pearlite is equal to or more than 95% and equal to or less than 100%,

an average block size of the pearlite is 10 μm to 30 nm, and standard deviation of block size is 20 μm or less, and

when Ceq. is obtained using formula (1) below, a tensile strength is equal to or more than 760×Ceq.+255 MPa and equal to or less than 760×Ceq.+325 MPa, reduction of area in a tensile test is −65×Ceq.+96(%) or more, and standard deviation of the reduction of area is 6% or less,

Ceq.=C(%)+Si(%)/24+Mn(%)/6  formula(1),

where C (%), Si (%), and Mn (%) represent contents in mass % of C, S, and Mn, respectively.

2. The high-carbon steel wire rod with excellent wire drawability according to claim 1 , further comprising chemical components of, in mass %,

one or two or more selected from the group consisting of

Al: 0.0001% to 0.010%,

Ti: 0.001% to 0.010%,

B: 0.0001% to 0.0015%,

Cr: 0.05% to 0.50%,

Ni: 0.05% to 0.50%,

V: 0.01% to 0.20%,

Cu: 0.05% to 0.20%,

Mo: 0.05% to 0.20%,

Nb: 0.01% to 0.10%,

Ca: 0.0005% to 0.0050%,

Mg: 0.0005% to 0.0050%, and

Zr: 0.0005% to 0.010%.

Assignments (2)
CHANGE OF NAME Recorded May 14, 2019
From: NIPPON STEEL & SUMITOMO METAL CORPORATION
To: NIPPON STEEL CORPORATION
Reel/Frame 049257/0828 →
ASSIGNMENT OF ASSIGNOR'S INTEREST Recorded Jan 27, 2017
From: OKONOGI, MAKOTO; HIRAKAMI, DAISUKE
To: NIPPON STEEL & SUMITOMO METAL CORPORATION
Reel/Frame 041102/0207 →