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US3725142A
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Atomized steel powder having improved hardenability
Assignee: AO Smith Inland Inc
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Filing: 1971-08-23
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Granted: 1973-04-03
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Expires: 1991-08-23
Abstract
Abstract Atomized steel powder having improved hardenability by the addition of boron. The powder is produced by atomizing a molten stream of steel containing 0.06 to 0.12 percent carbon and 0.005 to 0.100 percent boron. Following the atomization, the particles are annealed at a temperature of about 1500* to 2100* F. to soften the steel, as well as reducing the carbon content to a value below 0.05 percent. The annealed steel contains about 0.001 to 0.012 percent boron. After annealing, the cake-like structure is broken up to restore the as-atomized particle size and the particles are subsequently compacted into the shape of the desired part, sintered and heat treated to develop the desired hardness. The addition of boron aids in improving the hardenability of the part during heat treatment.
Inventors
- 👤 R Huseby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:10
CPC Classifications
C; C22; C22C; C22C33/00; C22C33/02; C22C33/0257; C22C33/0264; B; B22; B22F; B22F2998/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
89 words
Finely divided annealed steel powder having improved hardenability to be used in powder metallurgy processes, comprising a plurality of agglomerated steel particles consisting essentially by weight of 0.001 to 0.020 percent carbon; an element selected from the group consisting of 0.20 to 3.0 percent nickel, 0.20 to 1.0 percent chromium, 0.20 to 1.0 percent molybdenum and mixtures thereof; 0.01 to 0.80 percent manganese; 0.01 to 0.10 percent silicon; 0.001 to 0.002 percent boron; and the balance iron; said particles having improved hardenability on heat treatment after compaction and sintering.
Claim 2
Dependent Claim
20 words
The steel powder of claim 2, wherein said annealed steel has an oxygen content less than 0.40 percent by weight.
Claim 3
Independent Claim
197 words
A method of forming a steel part from a plurality of agglomerated steel particles, comprising the steps of atomizing a stream of molten steel consisting essentially of 0.06 to 0.12 percent by weight of carbon, and 0.005 to 0.100 percent by weight of boron, less than 0.8 percent manganese, less than 0.1 percent Si, and the balance iron to thereby provide a plurality of agglomerated steel particles, annealing the agglomerated particles in a reducing atmosphere at a temperature of 1500* to 2100* F. for a period of time to soften the particles and reduce the carbon content to a value less than 0.05 percent by weight and reduce the oxygen content to a value less than 0.40 percent by weight, compacting the annealed particles into the desired shape of a part, sintering the part at a temperature in the range of 2000* to 2300* F., heating the sintered part to a temperature in the range of 1475* to 1850* F., quenching the part, and tempering the part at a temperature in the range of 300* to 1000* F., the addition of boron improving the hardenability of the steel during the heat treatment following the compaction and sintering.
Claim 4
Dependent Claim
23 words
The method of claim 4, wherein the annealed particles have a boron content in the range of 0.001 to 0.012 percent by weight.
Claim 5
Dependent Claim
63 words
The method of claim 4, wherein the steel consists essentially by weight of 0.001 to 0.020 percent carbon; an element selected from the group consisting of 0.20 to 3.0 percent nickel, 0.20 to 1.0 percent chromium, 0.20 to 1.0 percent molybdenum and mixtures thereof; 0.01 to 0.80 percent manganese; 0.01 to 0.10 percent silicon; 0.001 to 0.002 percent boron; and the balance iron.
Claim 6
Independent Claim
237 words
A method of forming a steel part from a plurality of agglomerated steel particles, comprising the steps of forming a steel melt consisting essentially of from 0.06 to 0.12 percent by weight of carbon, less than 0.8 percent manganese, less than 0.1 percent silicon and the balance iron, adding a deoxidizing agent to only a portion of the melt to deoxidize said portion, said portion comprising from 5 to 25 percent by weight of the melt, adding boron to the deoxidized portion of the melt in an amount of 0.005 to 0.100 percent by weight of the entire melt and effecting solution of said boron in said portion, adding the remaining portion of the melt to said deoxidized portion to provide a blended melt, atomizing the blended melt to provide a plurality of agglomerated steel particles containing from 0.001 to 0.012 percent by weight of boron, annealing the particles to soften the particles and reduce the carbon content to a value in the range of 0.001 to 0.050 percent by weight, compacting the annealed particles into the desired shaPe of a part, sintering the part, heating the sintered part to a temperature in the range of 1475* to 1850* F., quenching the part, and tempering the part at a temperature in the range of 300* to 1000* F., the addition of boron improving the hardenability of the steel during the heat treatment following the compaction and sintering.
Claim 7
Dependent Claim
44 words
The method of claim 7, in which the deoxidizing agent is aluminum and is added to said portion of the melt in an amount sufficient to substantially completely deoxidize said portion, said aluminum comprising less than 0.010 percent by weight of the steel particles.
Claim 8
Independent Claim
220 words
A method of forming a steel part from a plurality of agglomerated steel particles, comprising the steps of forming a steel melt consisting essentially of from 0.06 to 0.12 percent by weight of carbon, less than 0.8 percent Mn, less than 0.1 percent silicon, and the balance iron, adding a calcium alloy to the melt in an amount sufficient to deoxidize the melt, adding boron to the melt in an amount sufficient to provide an elemental boron content of 0.001 to 0.012 percent by weight of the melt, atomizing a stream of the melt to thereby provide a plurality of agglomerated steel particles, annealing the agglomerated particles in a reducing atmosphere at a temperature of 1500* F. for a period of time to soften the particles and reduce the carbon content to a value less than 0.05 percent by weight and reduce the oxygen content to a value less than 0.40 percent by weight, compacting the annealed particles into the desired shape of a part, sintering the part, heating the sintered part to a temperature in the range of 1475* to 1850* F., quenching the part, and tempering the part at a temperature in the range of 300* to 1000* F., the addition of boron improving the hardenability of the steel during the heat treatment following the compaction and sintering.
Claim 9
Dependent Claim
21 words
The method of claim 9, wherein the calcium alloy is selected from the group consisting of calcium-silicon, calcium-manganese-silicon, and mixtures thereof.
Claim 10
Dependent Claim
59 words
The method of claim 9, wherein the calcium alloy is selected from the group consisting by weight of (a) 60 to 65 percent silicon, 30 to 33 percent calcium and 1.5 to 3 percent iron, (b) 16 to 20 percent calcium, 14 to 18 percent manganese and 54 to 59 percent silicon, and (c) mixtures of (a) and (b).
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-02 | 1976-10-02 | 1977-04-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-02 | 1980-10-02 | 1981-04-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-02 | 1984-10-02 | 1985-04-03 | $7700.00 | Window Closed / Lapsed |