US3847680A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dispersion strengthened metals and alloys and process for producing same
Assignee: Viridian Inc Canada
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Filing: 1972-11-01
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Granted: 1974-11-12
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Expires: 1992-11-01
Abstract
Abstract Wrought dispersion strengthened compositions having a metallic matrix comprised of nickel, cobalt or alloys of nickel and cobalt with each other and/or with chromium are prepared by first hot working a solid, fine grained workpiece formed from a powder composition containing uniformly dispersed, sub-micron refractory oxide particles and one or more of the desired metal constituents in the desired proportions to take at least a 15 percent reduction in cross-sectional area. During the hot working, the workpiece is maintained at an elevated temperature below the melting temperature of the workpiece matrix but above the minimum temperature at which dynamic recrystallization occurs in the workpiece microstructure. The hot-worked workpiece is then heat treated at a sufficiently high temperature and for a time sufficient to cause recrystallization of the metallic matrix and growth of large, equi-axed grains. The product is characterized by a coarse grained micro-structure which exhibits improved high temperature service characteristics and an absence of anisotropy.
Inventors
- 👤 D Fustukian
- 👤 B Kushnir
- 👤 L Norris
- 👤 R Fraser
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 14:21
CPC Classifications
C; C22; C22C; C22C32/00; C22C32/001; C22C32/0015; C22C32/0026; B; B22; B22F; B22F3/00; B22F3/24
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
205 words
A PROCESS FOR PRODUCING WROUGHT DISPERSION STRENGTHENED NICKEL, COBALT AND ALLOYS OF THESE METALS WITH EACH OTHER AND WITH CHROMIUM WHICH COMPRISES PROVIDING A SINTERED WORKPIECE FORMED FROM A POWDER COMPOSITION CONTANING UNIFORMLY DISPERSED SUBMICRON REFRACTORY OXIDE PARTICLES AND ONE OR MORE OF SAID METALS IN THE PROPORTION DESIRED IN THE FINAL WROUGHT PRODUCT, SAID WORKPIECE HAVING A GRAIN STRUCTURE CHARACTERIZED BY THE PRESENCE OF A SUBSTANTIAL PROPORTION OF SMALL GRAINS WHOSE GREATEST DIAMETER IS LESS THAN 30 MICRONS, HOT WORKING SAID WORKPIECE OF EFFECT A CROSS-SECTIONAL ARES A A REDUCTION AT LEAST SUFFICIENT TO ENSURE CONSOLIDATION OF THE WORKPIECE TO SUBSTANTIALLY FULL DENSITY AND TO EFFECT AT LEAST A 15 PERCENT REDUCTION IN CROSS-SECTIONAL AREA OF THE DENSIFIED WORKPIECE, MAINTAINING THE TEMPERATURE OF SAID WORKPIECE AT AN ELEVATED TEMPERATURE BELOW ITS MELTING TEMPERATURE BUT TO LOWER THAN THE MINIMUM TEMPERATURE AT WHICH DYNAMIC RECRYSTALLIZATION OCCURS IN THE MICROSTRUCTURE OF SAID WORKPIECE AT LEST WHILE EFFECTING THE FINAL 15 PERCENT REDUCTION IN CROSSSECTIONAL AREA OF THE FULLY DENSIFIED WORKPIECE, HEAT TREATING SAID HOT WORKED WORKPIECE AT A TEMPERATURE BELOW ITS MELTING TEMPERATURE BUT SUFFICIENTLY HIGH AND FOR A PERIOD OF TIME SUFFICIENT TO CAUSE RECRYSTALLIZATION AND GROWTH OF LARGE EQUIAXED GRAINS IN THE WORKPIECE MICROSTRUCTURE.
Claim 2
Dependent Claim
205 words
A PROCESS FOR PRODUCING WROUGHT DISPERSION STRENGTHENED NICKEL, COBALT AND ALLOYS OF THESE METALS WITH EACH OTHER AND WITH CHROMIUM WHICH COMPRISES PROVIDING A SINTERED WORKPIECE FORMED FROM A POWDER COMPOSITION CONTANING UNIFORMLY DISPERSED SUBMICRON REFRACTORY OXIDE PARTICLES AND ONE OR MORE OF SAID METALS IN THE PROPORTION DESIRED IN THE FINAL WROUGHT PRODUCT, SAID WORKPIECE HAVING A GRAIN STRUCTURE CHARACTERIZED BY THE PRESENCE OF A SUBSTANTIAL PROPORTION OF SMALL GRAINS WHOSE GREATEST DIAMETER IS LESS THAN 30 MICRONS, HOT WORKING SAID WORKPIECE OF EFFECT A CROSS-SECTIONAL ARES A A REDUCTION AT LEAST SUFFICIENT TO ENSURE CONSOLIDATION OF THE WORKPIECE TO SUBSTANTIALLY FULL DENSITY AND TO EFFECT AT LEAST A 15 PERCENT REDUCTION IN CROSS-SECTIONAL AREA OF THE DENSIFIED WORKPIECE, MAINTAINING THE TEMPERATURE OF SAID WORKPIECE AT AN ELEVATED TEMPERATURE BELOW ITS MELTING TEMPERATURE BUT TO LOWER THAN THE MINIMUM TEMPERATURE AT WHICH DYNAMIC RECRYSTALLIZATION OCCURS IN THE MICROSTRUCTURE OF SAID WORKPIECE AT LEST WHILE EFFECTING THE FINAL 15 PERCENT REDUCTION IN CROSSSECTIONAL AREA OF THE FULLY DENSIFIED WORKPIECE, HEAT TREATING SAID HOT WORKED WORKPIECE AT A TEMPERATURE BELOW ITS MELTING TEMPERATURE BUT SUFFICIENTLY HIGH AND FOR A PERIOD OF TIME SUFFICIENT TO CAUSE RECRYSTALLIZATION AND GROWTH OF LARGE EQUIAXED GRAINS IN THE WORKPIECE MICROSTRUCTURE.
Claim 3
Dependent Claim
55 words
The process according to claim 1 wherein the workpiece is a sintered, non-dense billet and consolidation to full density and reduction in cross-sectional area of the fully dense workpiece are both conducted at a temperature below the melting temperature of the workpiece, but above the temperature at which dynamic recrystallization occurs in the workpiece microstructure.
Claim 4
Dependent Claim
36 words
The process according to claim 1 wherein the starting workpiece is a substantially fully dense billet having a grain structure characTerized by a substantial proportion of grains whose greatest diameter is less than about 10 microns.
Claim 5
Dependent Claim
24 words
The process according to claim 1 wherein the hot working is carried out at a temperature above the recrystallization temperature of the workpiece microstructure.
Claim 6
Dependent Claim
30 words
The process according to claim 1 wherein consolidation and reduction in cross-sectional area are effected by a single hot rolling reduction carried out at a temperature of about 1,200* C.
Claim 7
Dependent Claim
21 words
The process according to claim 1 wherein the sintered workpiece is sheathed in mild steel prior to the hot working operation.
Claim 8
Dependent Claim
27 words
The process according to claim 1 wherein the heat treating step is conducted at a temperature in the range of about 1,200* C. to about 1,425* C.
Claim 9
Dependent Claim
31 words
The process according to claim 1 wherein the fully dense workpiece is worked in said hot working operation to take a cross-sectional area reduction of between 20 percent and 40 percent.
Claim 10
Dependent Claim
38 words
The process according to claim 1 wherein the workpiece is formed of nickel powder particles in the size range of 0.5 to 10 microns and containing from about 0.2 to about 4.0 percent by volume submicron thoria particles.
Claim 11
Dependent Claim
26 words
The process according to claim 1 wherein the workpiece is formed of finely divided cobalt particles containing 0.2 to 4.0 percent by volume submicron thoria particles.
Claim 12
Dependent Claim
50 words
The process according to claim 1 including an additional step in which the heat treated workpiece is subjected to a secondary hot working operation with the temperature of the workpiece being maintained at least as high as the temperature employed for the final stage of the initial hot working operation.
Claim 13
Dependent Claim
25 words
The process according to claim 11 wherein the additional hot working step is effected by hot rolling to take a reduction up to 80 percent.
Claim 14
Dependent Claim
174 words
A process for fabricating wrought dispersion strengthened nickel-chromium alloy compositions having improved isotropic high temperature strength characteristics which comprises forming a compacted billet from a powder composition comprising nickel, from 10 to 35 percent chromium and from about 0.2-4.0 percent by volume uniformly distributed discrete, submicron refractory oxide particles, sintering the said billet at a temperature between 1, 100* C. and 1,350* C. to provide a coherent workpiece, hot working said workpiece to effect a cross-sectional area reduction sufficient to consolidate the billet to substantially full density and to take at least a 15 percent cross-sectional area reduction of the consolidated billet, maintaining the temperature of said workpiece below its melting point but above about 1,200* C. during said hot working operation to cause dynamic recrystallization to occur in the workpiece microstructure during said hot working, and heat treating the hot worked workpiece at a temperature between 1,200* F. and 1,370* F. for a sufficient time to cause recrystallization and development of large, equi-axed grains within the size range of 50-100 microns average diameter.
Claim 15
Dependent Claim
174 words
A process for fabricating wrought dispersion strengthened nickel-chromium alloy compositions having improved isotropic high temperature strength characteristics which comprises forming a compacted billet from a powder composition comprising nickel, from 10 to 35 percent chromium and from about 0.2-4.0 percent by volume uniformly distributed discrete, submicron refractory oxide particles, sintering the said billet at a temperature between 1, 100* C. and 1,350* C. to provide a coherent workpiece, hot working said workpiece to effect a cross-sectional area reduction sufficient to consolidate the billet to substantially full density and to take at least a 15 percent cross-sectional area reduction of the consolidated billet, maintaining the temperature of said workpiece below its melting point but above about 1,200* C. during said hot working operation to cause dynamic recrystallization to occur in the workpiece microstructure during said hot working, and heat treating the hot worked workpiece at a temperature between 1,200* F. and 1,370* F. for a sufficient time to cause recrystallization and development of large, equi-axed grains within the size range of 50-100 microns average diameter.
Claim 16
Dependent Claim
20 words
The process according to claim 13 wherein the coherent workpiece is sheathed in mild steel sheet prior to hot working.
Claim 17
Dependent Claim
28 words
The process according to claim 13 wherein hot working is conducted to effect a cross-sectional area reduction of the consolidated workpiece of between 20 percent and 40 percent.
Claim 18
Dependent Claim
37 words
The process according to claim 13 including the additional step of hot working the heat treated workpiece at a temperature between 1,100* C. and 1,315* C. to take a cross-sectional area reduction of up to 80 percent.
Claim 19
Dependent Claim
71 words
The process according to claim 13 wherein the compacted billet is formed from a blended mixture of finely divided nickel powder, chromium powder and refractory oxide particles and the billet is sintered in an atmosphere of hydrogen having a dew point below about -45* C. for a sufficient period of time to reduce oxygen in excess of that combined with the refractory oxide constituent to below about 0.1 percent by weight.
Claim 20
Dependent Claim
23 words
The process according to claim 13 wherein said billet is formed from a powder composition comprising finely divided pre-alloyed nickel-chromium alloy-refractory oxide particles.
Claim 21
Dependent Claim
26 words
The process according to claim 13 wherein said powder composition contains about 20 percent by weight chromium and from about 0.2 to about 4.0 percent thoria.
References Cited (Backward Citations)
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US3388010A
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US3446679A
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US3494807A
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US3595710A
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US3746581A
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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) | 1977-11-11 | 1978-05-13 | 1978-11-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-11-11 | 1982-05-13 | 1982-11-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-11-11 | 1986-05-13 | 1986-11-12 | $7700.00 | Window Closed / Lapsed |