# US 12,597,542 B2 · Soft magnetic iron

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- Number: US 12,597,542 B2
- Document ID: US12597542B2
- Status: Granted
- Kind: B2
- Application number: 18/248,525
- Filed: 2021-10-22
- Published: 2023-12-21
- Granted: 2026-04-07
- Earliest claimed: 2020-10-29
- Assignees: Jfr Steel Corporation
- Applicants: Jfe Steel Corporation
- Inventors: Katsuyuki Ichimiya; Koichi Nakashima; Yuta Imanami
- Web page: https://patentgrep.com/patent/US12597542B2

## CPC

- H01F 1/147: Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)}
- C21D 6/005: {containing Mn}
- 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 38/004: {Very low carbon steels, i.e. having a carbon content of less than 0,01%}
- C22C 38/005: {containing rare earths, i.e. Sc, Y, Lanthanides}
- 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 38/32: with boron
- C22C 38/60: containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- 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)
- C22C: ALLOYS (treatment of alloys C21D, C22F)

## Abstract

Provided is a technique that can achieve both magnetic properties and machinability by cutting at a high level, which has been impossible with only the conventional techniques of improving the machinability by cutting using MnS or the like. A soft magnetic iron comprises a chemical composition containing, in mass %, C: less than 0.02%, Si: less than 0.05%, Mn: more than 0.03% and 0.50% or less, P: 0.002% or more and less than 0.006%, S: 0.013% or more and 0.050% or less, Al: 0.010% or less, N: 0.0010% or more and 0.0100% or less, and B: 0.0003% or more and 0.0065% or less, with a balance consisting of iron and inevitable impurities.

## Claims

### Claim 1

A soft magnetic iron comprising a chemical composition consisting of, in mass %,
C: less than 0.02%,
Si: less than 0.05%,
Mn: more than 0.03% and 0.50% or less,
P: 0.002% or more and 0.005% or less,
S: 0.013% or more and 0.050% or less,
Al: 0.010% or less,
N: 0.0010% or more and 0.0100% or less, and
B: 0.0003% or more and 0.0065% or less,
and optionally, in mass %, one or more selected from the group consisting of
Cu: 0.20% or less,
Ni: 0.30% or less,
Cr: 0.30% or less,
Mo: 0.10% or less,
V: 0.02% or less,
Nb: less than 0.015%,
Ti: less than 0.010%,
Pb: 0.30% or less,
Bi: 0.30% or less,
Te: 0.30% or less,
Se: 0.30% or less,
Ca: 0.0100% or less,
Mg: less than 0.0050%,
Zr: 0.200% or less, and
REM: 0.0100% or less,
with a balance consisting of iron and inevitable impurities,
wherein a magnetic flux density at 100 A/m in a magnetization process with a peak magnetic field of 10,000 A/m is 1.20 T or more, a magnetic flux density at 300 A/m in a magnetization process with a peak magnetic field of 10.000 A/m is 1.50 T or more, and a coercive force measured with a reversal magnetization force of ±400 A/m is 60 A/m or less,
wherein a critical upset ratio, which is an upset ratio when a crack occurred during successive compression, is 55% or more, and
wherein a flank wear, which is measured after a cutting work with a cut depth of 0.2 mm, a feed rate of 0.15 mm/rev, a peripheral speed of 300 m/min, wet type, and a length of cut of 1000 m, is 35 μm or less.

### Claim 2 (depends on 1)

The soft magnetic iron according to claim 1, wherein the soft magnetic iron is in a form of a bar, a rod, or a wire.