US3900309A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the production of high apparent density water atomized steel powders
Assignee: United States Steel Corp
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Filing: 1973-08-16
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Granted: 1975-08-19
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Expires: 1993-08-16
Abstract
Abstract The apparent density of molding-grade, water atomized steel powder can be significantly increased by employing the following prescribed treatment. Coarse particles are removed in order that at least 80% of the initial powders are finer than 80 mesh. The size distribution of the powders is then determined. The powders are then annealed to both reduce the carbon and oxygen contents and soften the particles. The annealed and agglomerated particles are then ground in a disk mill at specified speeds and gap spacings, depending on the size distribution of the initial powders. Apparent densities in excess of 3.2 may be achieved by (a) employing powders with a coarser particle size distribution, (b) increasing the rotational speed of the disks and (c) decreasing the mill gap.
Inventors
- 👤 Hung-Chi Chao
- 👤 John H Gross
- 👤 Robert R Judd
- 👤 Roger L Rueckl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:16
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/02; B22F9/04
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
179 words
A METHOD FOR THE PRODUCTION OF OLDING GRADE STEEL POWDERS WITH HIGH APPARENT DENSITIES, WHICH COMPRISES, A. PROVIDING AS-WATER-ATOMIZED STEEL PARTICLES WITH A PRESCRIBED SIZE DISTRIBUTION, WHEREIN AT LEAST 80% OF SAID PARTICLES ARE FINER THAN 80 MESH AND SAID DISTRIBUTION EXHIBITS A PSC VALUE OF BETWEEN 2.0 TO 4.0, B. ANNEALING SAID PARTICLES AT A TEMPERATURE WITHIN THE RANGE OF 1400*-2100*F FOR A TIME AT LEAST SUFICIENT TO (I) EFFECT THE DESIRED SOFTENING THEREOF, AND (22) REDUCE THE OXYGEN CONTENT THEREOF TO A VALUE BELOW ABOUT 0.2 WEIGHT PER CENT, SAID ANNEALING CAUSING SAID PARTICLES TO SINTER TOGETHER, C. FEEDING THE ANNEALED, SINTERED PARTICLES TO A DISK MILL OPERATED AT A SPEED OF BETWEEN ABOUT 200 TO 5000 REVOLUTIONS PER MINUTE AND A MLL GAP OF BETWEEN ABOUT 0.01 TO 0.10 INCHES, WHEREIN THE LINEAR SPEED V OF SAID DISKS IS SUFFICIENTLY HIGH AND THE MILL GAP G IS SUFFICIENTLY CLOSE TO GRIND SAID SINTERED PARTICLES TO MOLDING GRADE POWDERS WITH AN APPARENT DENSITY IN EXCESS OF 3,2 GM/CC, SUBSTANTIALLY ALL OF WHICH ARE FINER THAN 80 MESH
Claim 2
Independent Claim
179 words
A METHOD FOR THE PRODUCTION OF OLDING GRADE STEEL POWDERS WITH HIGH APPARENT DENSITIES, WHICH COMPRISES, A. PROVIDING AS-WATER-ATOMIZED STEEL PARTICLES WITH A PRESCRIBED SIZE DISTRIBUTION, WHEREIN AT LEAST 80% OF SAID PARTICLES ARE FINER THAN 80 MESH AND SAID DISTRIBUTION EXHIBITS A PSC VALUE OF BETWEEN 2.0 TO 4.0, B. ANNEALING SAID PARTICLES AT A TEMPERATURE WITHIN THE RANGE OF 1400*-2100*F FOR A TIME AT LEAST SUFICIENT TO (I) EFFECT THE DESIRED SOFTENING THEREOF, AND (22) REDUCE THE OXYGEN CONTENT THEREOF TO A VALUE BELOW ABOUT 0.2 WEIGHT PER CENT, SAID ANNEALING CAUSING SAID PARTICLES TO SINTER TOGETHER, C. FEEDING THE ANNEALED, SINTERED PARTICLES TO A DISK MILL OPERATED AT A SPEED OF BETWEEN ABOUT 200 TO 5000 REVOLUTIONS PER MINUTE AND A MLL GAP OF BETWEEN ABOUT 0.01 TO 0.10 INCHES, WHEREIN THE LINEAR SPEED V OF SAID DISKS IS SUFFICIENTLY HIGH AND THE MILL GAP G IS SUFFICIENTLY CLOSE TO GRIND SAID SINTERED PARTICLES TO MOLDING GRADE POWDERS WITH AN APPARENT DENSITY IN EXCESS OF 3,2 GM/CC, SUBSTANTIALLY ALL OF WHICH ARE FINER THAN 80 MESH
Claim 3
Dependent Claim
55 words
The method of claim 1, wherein said linear speed v and said mill gap G are correlated with the PSC value of said particles in accord with the following equation: +0.30 PSC -1.28 .10 5v +2.87 .10 2 LG +1.93 .10 6 .v PSC +4.00 .10 11 .v2 -3.96 .10 6 .v. LG > 1.04
Claim 4
Dependent Claim
26 words
The method of claim 2, wherein at least 95% of said as-water-atomized particles are finer than 80 mesh, with a major portion finer than 200 mesh.
Claim 5
Dependent Claim
27 words
The method of claim 2, wherein the carbon content of said as-atomized particles is less than 0.15% and said annealing temperature is between about 1700* and 1900*F.
Claim 6
Dependent Claim
75 words
The method of claim 4, wherein the PSC value of said atomized particles is greater than about 2.5 and the speed v and mill gap G are correlated with said PSC value in accord with the following equation: +0.30 PSC -1.28.10 5v +2.87.10 2 LG +1.93 .10 6 .v.PSC +4.00 .10 11 v2 -3.96 .10 6 .v. LG > 1.24 to yield a molding grade powder product with an apparent density greater than 3.4 gm/cc.
Claim 7
Dependent Claim
26 words
The method of claim 5, wherein at least 95% of said as-water-atomized particles are finer than 80 mesh, with a major portion finer than 200 mesh.
References Cited (Backward Citations)
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US3668024A
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US3687654A
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US3764295A
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US3725142A
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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) | 1978-08-18 | 1979-02-17 | 1979-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-18 | 1983-02-17 | 1983-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-18 | 1987-02-17 | 1987-08-19 | $7700.00 | Window Closed / Lapsed |