# US 11,441,212 B2 · Alloyed steel powder

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- Number: US 11,441,212 B2
- Document ID: US11441212B2
- Status: Granted
- Kind: B2
- Application number: 16/769,240
- Filed: 2018-11-30
- Published: 2021-06-17
- Granted: 2022-09-13
- Earliest claimed: 2017-12-05
- Assignees: Jfe Steel Corporation
- Applicants: Jfe Steel Corporation
- Inventors: Takuya Takashita; Akio Kobayashi; Naomichi Nakamura
- Web page: https://patentgrep.com/patent/US11441212B2

## CPC

- C22C 38/04: containing manganese
- B22F 1/05: Metallic powder characterised by the size or surface area of the particles
- B22F 3/16: in successive or repeated steps
- B22F 9/04: starting from solid material, e.g. by crushing, grinding or milling ({C22C1/1084 takes precedence}; crushing, grinding or milling, in general, see the relevant subclasses, e.g. B02C)
- C22C 33/0207: {Using a mixture of pre-alloyed powders or a master alloy}
- C22C 33/0264: {the maximum content of each alloying element not exceeding 5%}
- C22C 38/12: containing tungsten, tantalum, molybdenum, vanadium, or niobium
- C22C 38/16: containing copper
- B22F 2009/041: {by mechanical alloying, e.g. blending, milling}
- B22F 2201/013: Hydrogen
- B22F 2998/00: Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F 2998/10: Processes characterised by the sequence of their steps
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER

## Abstract

Provided is alloyed steel powder having excellent fluidity, formability, and compressibility without containing Ni, Cr, or Si. The alloyed steel powder includes iron-based alloy containing Mo, in which Mo content is 0.4 mass % to 1.8 mass %, a weight-based median size D50 is 40 μm or more, and among particles contained in the alloyed steel powder, those particles having an equivalent circular diameter of 50 μm to 200 μm have a number average of solidity of 0.70 to 0.86, the solidity being defined as (particle cross-sectional area/envelope-inside area).

## Claims

### Claim 1

A pre-alloyed steel powder comprising iron-based alloy containing Mo, wherein
Mo content is 0.4 mass % to 1.8 mass %,
a weight-based median size D50 is 40 μm or more,
among particles contained in the alloyed steel powder, those particles having an equivalent circular diameter of 50 μm to 200 μm have a number average of solidity of 0.70 to 0.86, the solidity being defined as (particle cross-sectional area/envelope-inside area), and
the number average of solidity is obtained by measuring particle cross-sectional area and envelope-inside area for at least 10,000 particles having an equivalent circular diameter of 50 μm to 200 μm through image interpretation of the projected image of each of the particles using Malvern Morphologi G3, obtaining the solidity by calculating (cross-sectional area/envelope-inside area) for each of the particles, and calculating the number average thereof.

### Claim 2 (depends on 1)

The pre-alloyed steel powder according to claim 1, wherein the iron-based alloy contains Ni, Cr, and Si each in an amount of 0.1 mass % or less.

### Claim 3 (depends on 1)

The pre-alloyed steel powder according to claim 1, wherein the iron-based alloy contains one or both of Cu and Mn.

### Claim 4 (depends on 2)

The pre-alloyed steel powder according to claim 2, wherein the iron-based alloy contains one or both of Cu and Mn.