Non-heat treated steel bar

Patent metadata

Field	Value
Publication number	US-11111569-B2
Application number	US-201816486563-A
Country	US
Kind code	B2
Filing date	Feb 23, 2018
Priority date	Feb 24, 2017
Publication date	Sep 7, 2021
Grant date	Sep 7, 2021

Abstract

A non-heat treated steel bar according to the present disclosure has a chemical composition consisting of, in mass percent, C: 0.39 to 0.55%, Si: 0.10 to 1.00%, Mn: 0.50 to 1.50%, P: 0.010 to 0.100%, S: 0.040 to 0.130%, Cr: 0.05 to 0.50%, V: 0.05 to 0.40%, Ti: 0.10% to 0.25%, Al: 0.003 to 0.100%, and N: 0.020% or less, with the balance being Fe and impurities, and satisfying Formula (1). A number density of Al2O3-based inclusions in each of which Al2O3 is contained at 70.0% or more in mass % and √AREA is not less than 3 μm is 0.05 to 1.00/mm2.0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00  (1)

First claim

The invention claimed is:

1. A non-heat treated steel bar comprising a chemical composition consisting of, in mass percent:
C: 0.39 to 0.55%;
Si: 0.10 to 1.00%;
Mn: 0.50 to 1.50%;
P: 0.010 to 0.100%;
S: 0.040 to 0.130%;
Cr: 0.05 to 0.50%;
V: 0.05 to 0.40%;
Ti: 0.10% to 0.25%;
Al: 0.003 to 0.100%;
N: 0.020% or less;
Cu: 0 to 0.40%;
Ni: 0 to less than 0.20%;
Mo: 0 to 0.10%;
Pb: 0 to 0.30%;
Te: 0 to 0.3000%;
Ca: 0 to 0.0100%; and
Bi: 0 to 0.3000%, with the balance being Fe and impurities including oxygen, the chemical composition satisfying Formula (1), wherein
in the steel bar, a number density of Al 2 O 3 -based inclusions in each of which Al 2 O 3 is contained at 70.0% or more in mass percent and √AREA is not less than 3 μm is 0.05 to 1.00/mm 2 :
0.60≤C+0.2Mn+0.25Cr+0.75V+0.81Mo≤1.00  (1)

where symbols of elements in Formula (1) are to be substituted by contents of corresponding elements (in mass percent).

2. The non-heat treated steel bar according to claim 1 , wherein the chemical composition contains one or more types of element selected from the group consisting of:
Cu: 0.01 to 0.40%;
Ni: 0.01 to less than 0.20%; and
Mo: 0.01 to 0.10%.

3. The non-heat treated steel bar according to claim 2 , wherein the chemical composition contains one or more types of element selected from the group consisting of:
Pb: 0.05 to 0.30%;
Te: 0.0003 to 0.3000%;
Ca: 0.0003 to 0.0100%; and
Bi: 0.0003 to 0.3000%.

4. The non-heat treated steel bar according to claim 1 , wherein the chemical composition contains one or more types of element selected from the group consisting of:
Pb: 0.05 to 0.30%;
Te: 0.0003 to 0.3000%;
Ca: 0.0003 to 0.0100%; and
Bi: 0.0003 to 0.3000%.

Assignees

• Nippon Steel Corp

Inventors

• Miyakoshi Yusuke
• Takasuga Motoki

Classifications

• C21D8/00

  Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment (hardening articles or materials formed by forging or rolling with no further heating beyond that required for the formation C21D1/02) · CPC title

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C22C38/46

  with vanadium · CPC title

• C22C29/12

  based on oxides · CPC title

• C22C38/02

  containing silicon · CPC title