US4448746A
Expired / Lapsed
US
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Process for producing alloy steel powder
Assignee: Nippon Steel Corp
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Filing: 1982-11-05
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Granted: 1984-05-15
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Expires: 2002-11-05
Abstract
Abstract A process for producing alloy steel powder, particularly, low-oxygen, low-carbon alloy steel powder is disclosed. The process comprises: preparing molten steel which contains at least one easily oxidizable element selected from the group consisting of chromium, manganese, vanadium, niobium, boron and silicon; atomizing said molten steel by means of an atomizing agent containing a non-oxidizing medium to provide as-atomized alloy steel powder containing 0.2% by weight or less of oxygen and 0.1% by weight or more of carbon; decarburizing the resulting powder by maintaining it in an atmosphere containing at least H2 and H2O gases under specified conditions; and cooling the thus decarburized alloy steel powder to room temperature in an inert or reducing atmosphere.
Inventors
- 👤 Toshihiko Kubo
- 👤 Minoru Ichidate
- 👤 Eijiro Tamura
- 👤 Isamu Karasuno
- 👤 Masahide Umino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 06:35
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/02; B22F9/06; B22F9/08; B22F9/082; B22F1/00; B22F1/14; B22F1/145; B22F2009/0824; B22F2999/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
186 words
A process for producing low-oxygen, low-carbon alloy steel powder, which comprises the steps of: preparing molten steel which contains at least one easily oxidizable element selected from the group consisting of chromium, manganese, vanadium, niobium, boron and silicon; atomizing said molten steel by means of an atomizing agent containing a non-oxidizing medium to provide as-atomized alloy steel powder containing 0.2% by weight or less of oxygen and 0.1% by weight or more of carbon; adjusting the amount of carbon of said as-atomized alloy steel powder by maintaining it in a decarburizing atmosphere containing at least H 2 and H 2 O gases under either of the below-defined conditions (A) or (B); and cooling the thus obtained alloy steel powder to room temperature in an inert or reducing atmosphere. Condition (A): Temperature (t°C.): 600° C.≦t≦950° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): 0.5≦P H .sbsb.2 /P H .sbsb.2 O ≦1000 Treating Time (θ minute): ##EQU8## Condition (B): Temperature (t°C.): 950° C.<t≦1250° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): P H .sbsb.2 /P H .sbsb.2 O ≧0.5 Treating Time (θ minute): ##EQU9##
Claim 2
Dependent Claim
186 words
A process for producing low-oxygen, low-carbon alloy steel powder, which comprises the steps of: preparing molten steel which contains at least one easily oxidizable element selected from the group consisting of chromium, manganese, vanadium, niobium, boron and silicon; atomizing said molten steel by means of an atomizing agent containing a non-oxidizing medium to provide as-atomized alloy steel powder containing 0.2% by weight or less of oxygen and 0.1% by weight or more of carbon; adjusting the amount of carbon of said as-atomized alloy steel powder by maintaining it in a decarburizing atmosphere containing at least H 2 and H 2 O gases under either of the below-defined conditions (A) or (B); and cooling the thus obtained alloy steel powder to room temperature in an inert or reducing atmosphere. Condition (A): Temperature (t°C.): 600° C.≦t≦950° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): 0.5≦P H .sbsb.2 /P H .sbsb.2 O ≦1000 Treating Time (θ minute): ##EQU8## Condition (B): Temperature (t°C.): 950° C.<t≦1250° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): P H .sbsb.2 /P H .sbsb.2 O ≧0.5 Treating Time (θ minute): ##EQU9##
Claim 3
Dependent Claim
26 words
The process of claim 1, in which said non-oxidizing medium is selected from the group consisting of mineral oils, animal oils, vegetable oils and mixtures thereof.
Claim 4
Dependent Claim
20 words
The process of claim 1, in which said decarburizing atmosphere is comprised of H 2 and H 2 O gases.
Claim 5
Dependent Claim
23 words
The process of claim 1, in which said decarburizing atmosphere is comprised of H 2 , H 2 O and N 2 gases.
Claim 6
Dependent Claim
22 words
The process of claim 3, in which the oxygen content of said as-atomized alloy steel powder is 0.1% by weight or less.
Claim 7
Dependent Claim
22 words
The process of claim 4, in which the oxygen content of said as-atomized alloy steel powder is 0.1% by weight or less.
Claim 8
Dependent Claim
22 words
The process of claim 5, in which the oxygen content of said as-atomized alloy steel powder is 0.05% by weight or less.
Claim 9
Dependent Claim
22 words
The process of claim 6, in which the oxygen content of said as-atomized alloy steel powder is 0.05% by weight or less.
Claim 10
Dependent Claim
190 words
A process for producing low-oxygen, low-carbon alloy steel powder, which comprises the steps of: preparing molten steel which contains at least one easily oxidizable element selected from the group consisting of chromium, manganese, vanadium, niobium, boron and silicon; atomizing said molten steel by means of an atomizing agent containing a non-oxidizing medium to provide as-atomized alloy steel powder containing 0.2% by weight or less of oxygen and 0.1% by weight or more of carbon; continuously passing said as-atomized alloy steel powder through an atmosphere containing at least H 2 and H 2 O gases under either of the below-defined conditions (A) or (B) to adjust the amount of carbon of said as-atomized alloy steel powder; and cooling the thus obtained alloy steel powder to room temperature in an inert or reducing atmosphere. Condition (A): Temperature (t°C.): 600° C.≦t≦950° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): 0.5≦P H .sbsb.2 /P H .sbsb.2 O ≦1000 Treating Time (θ minute): ##EQU10## Condition (B): Temperature (t°C.): 950° C.<t≦1250° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): P H .sbsb.2 /P H .sbsb.2 O ≧0.5 Treating Time (θ minute): ##EQU11##
Claim 11
Dependent Claim
190 words
A process for producing low-oxygen, low-carbon alloy steel powder, which comprises the steps of: preparing molten steel which contains at least one easily oxidizable element selected from the group consisting of chromium, manganese, vanadium, niobium, boron and silicon; atomizing said molten steel by means of an atomizing agent containing a non-oxidizing medium to provide as-atomized alloy steel powder containing 0.2% by weight or less of oxygen and 0.1% by weight or more of carbon; continuously passing said as-atomized alloy steel powder through an atmosphere containing at least H 2 and H 2 O gases under either of the below-defined conditions (A) or (B) to adjust the amount of carbon of said as-atomized alloy steel powder; and cooling the thus obtained alloy steel powder to room temperature in an inert or reducing atmosphere. Condition (A): Temperature (t°C.): 600° C.≦t≦950° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): 0.5≦P H .sbsb.2 /P H .sbsb.2 O ≦1000 Treating Time (θ minute): ##EQU10## Condition (B): Temperature (t°C.): 950° C.<t≦1250° C. Atmosphere (P H .sbsb.2 /P H .sbsb.2 O ): P H .sbsb.2 /P H .sbsb.2 O ≧0.5 Treating Time (θ minute): ##EQU11##
Claim 12
Dependent Claim
44 words
The process of claim 9, in which said as-atomized alloy steel powder is continuously passed through a decarburizing zone comprised of a pre-heating section, a decarburizing section and a cooling section, said pre-heating and cooling sections being kept in an inert or reducing atmosphere.
Claim 13
Dependent Claim
26 words
The process of claim 9, in which said non-oxidizing medium is selected from the group consisting of mineral oils, animal oils, vegetable oils and mixtures thereof.
Claim 14
Dependent Claim
20 words
The process of claim 9, in which said decarburizing atmosphere is comprised of H 2 and H 2 O gases.
Claim 15
Dependent Claim
23 words
The process of claim 9, in which said decarburizing atmosphere is comprised of H 2 , H 2 O and N 2 gases.
Claim 16
Dependent Claim
22 words
The process of claim 12, in which the oxygen content of said as-atomized alloy steel powder is 0.1% by weight or less.
Claim 17
Dependent Claim
22 words
The process of claim 13, in which the oxygen content of said as-atomized alloy steel powder is 0.1% by weight or less.
Claim 18
Dependent Claim
22 words
The process of claim 14, in which the oxygen content of said as-atomized alloy steel powder is 0.05% by weight or less.
Claim 19
Dependent Claim
22 words
The process of claim 15, in which the oxygen content of said as-atomized alloy steel powder is 0.05% by weight or less.
References Cited (Backward Citations)
US2498769A
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US3668024A
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US3687654A
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US3725142A
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US3887402A
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US4124377A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-05-15 | 1987-11-14 | 1988-05-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-15 | 1991-11-14 | 1992-05-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-15 | 1995-11-14 | 1996-05-15 | $7700.00 | Window Closed / Lapsed |