# US 11,111,569 B2 · Non-heat treated steel bar

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- Number: US 11,111,569 B2
- Document ID: US11111569B2
- Status: Granted
- Kind: B2
- Application number: 16/486,563
- Filed: 2018-02-23
- Published: 2020-02-20
- Granted: 2021-09-07
- Earliest claimed: 2017-02-24
- Assignees: Nippon Steel Corporation
- Applicants: Nippon Steel Corporation
- Inventors: Yusuke Miyakoshi; Motoki Takasuga
- Web page: https://patentgrep.com/patent/US11111569B2

## CPC

- C22C 38/50: with titanium or zirconium
- C21C 7/04: Removing impurities by adding a treating agent
- C21C 7/064: Dephosphorising; Desulfurising
- C21C 7/10: Handling in a vacuum
- C22C 29/12: based on oxides
- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- C22C 38/001: {containing N}
- C22C 38/002: {containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60}
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/08: containing nickel {(C22C38/105 takes precedence)}
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/14: containing titanium or zirconium
- C22C 38/16: containing copper
- C22C 38/18: containing chromium
- C22C 38/20: with copper
- C22C 38/22: with molybdenum or tungsten
- C22C 38/24: with vanadium
- C22C 38/28: with titanium or zirconium
- C22C 38/40: with nickel
- C22C 38/42: with copper
- C22C 38/44: with molybdenum or tungsten
- C22C 38/46: with vanadium
- C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
- C21C 7/06: Deoxidising, e.g. killing
- C21D 8/00: 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)
- C21D 8/06: during manufacturing of rods or wires
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C21C: PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)

## 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)

## Claims

### Claim 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 Al2O3-based inclusions in each of which Al2O3is contained at 70.0% or more in mass percent 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)
where symbols of elements in Formula (1) are to be substituted by contents of corresponding elements (in mass percent).

### Claim 2 (depends on 1)

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%.

### Claim 3 (depends on 2)

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%.

### Claim 4 (depends on 1)

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%.