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US3663312A
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US
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Nitride-strengthened, stainless steel
Assignee: Allegheny Ludlum Corp
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Filing: 1970-03-09
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Granted: 1972-05-16
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Expires: 1990-03-09
Abstract
Abstract An article comprising at least one layer which consists essentially of a nitride-strengthened, austenitic stainless steel. The steel contains as a dispersoid therein particles of metal nitride having a free energy of formation of greater than 21,000 cal./mole, present at an interparticle spacing of less than about 10 microns and has a microstructure comprised of elongated primary grains which contain twins and sub-grains; wherein a substantial number of said primary grains are greater than 20 microns wide and substantially longer than 40 microns. A method of forming a nitride-strengthened, austenitic stainless steel having a microstructure comprised of elongated primary grains which contain twins and sub-grains; wherein a substantial number of said primary grains are greater than 20 microns wide and substantially longer than 40 microns. It comprises the steps of: providing a nitride-strengthened, austenitic stainless steel which contains as a dispersoid therein particles of metal nitride having a free energy of formation of greater than - 21,000 cal./mole, present at an interparticle spacing of less than about 10 microns; warm working the steel at a temperature below its recrystallization temperature; and annealing the steel at a temperature at or in excess of its germination temperature.
Inventors
- 👤 Lynn E Kindlimann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:17
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/18; C22C38/40; C22C38/50
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
25 words
An article according to claim 1 wherein said dispersoid is a nitride of a metal from the group consisting of titanium, aluminum, vanadium and columbium.
Claim 2
Dependent Claim
12 words
An article according to claim 1 wherein said dispersoid is titanium nitride.
Claim 3
Dependent Claim
22 words
An article according to claim 1 wherein said dispersoid particles are present at an interparticle spacing of less than about 2 microns.
Claim 4
Dependent Claim
30 words
An article according to claim 1 wherein said dispersoid is titanium nitride and wherein said titanium nitride particles are present at an interparticle spacing of less thaN about 1 micron.
Claim 5
Dependent Claim
41 words
An article according to claim 1 wherein said dispersoid is a nitride of metal from the group consisting of titanium, aluminum, vanadium and columbium and wherein said dispersoid particles are present at an interparticle spacing of less than about 0.5 micron.
Claim 6
Dependent Claim
21 words
An article according to claim 1 wherein said elongated primary grains comprise at least about about 20 percent of said microstructure.
Claim 7
Dependent Claim
20 words
An article according to claim 1 wherein said elongated primary grains comprise at least about 50 percent of said microstructure.
Claim 8
Dependent Claim
29 words
An article according to claim 7 wherein said dispersoid is titanium nitride wherein said titanium nitride particles are present at an interparticle spacing of less than about 2 microns.
Claim 9
Dependent Claim
42 words
An article according to claim 8 wherein said dispersoid is a nitride of a metal from the group consisting of titanium, aluminum, vanadium and columbium and wherein said dispersoid particles are present at an interparticles spacing of less than about 1.0 micron.
Claim 10
Dependent Claim
19 words
An article according to claim 1 including at least one layer which is dissimilar to nitride-strengthened, austenitic stainless steel.
Claim 11
Dependent Claim
30 words
An article according to claim 1 wherein each layer of nitride-strengthened, austenitic stainless steel has a rupture strength of no less than about 4 ksi for 200 hours at 2000*F.
Claim 12
Independent Claim
85 words
A method of improving the high temperature properties of nitride-strengthened, austenitic stainless steel which comprises the steps of: providing a nitride-strengthened, austenitic stainless steel containing as a dispersoid therein particles of metal nitride present at an interparticle spacing of less than about 10 microns and having a free energy of formation of grater than -21,000 cal. /mole at room temperature; warm working said steel at a temperature below its recrystallization temperature; and annealing said steel at a temperature at least equal to its germination temperature.
Claim 13
Dependent Claim
21 words
A method according to claim 13 wherein said warm working is at a temperature of from about 800*F to about 2,100*F.
Claim 14
Dependent Claim
18 words
A method according to claim 13 wherein said annealing is at a temperature of at least about 2,300*F.
Claim 15
Dependent Claim
25 words
A method according to claim 13 wherein said dispersoid is a nitride of a metal from the group consisting of titanium, aluminum, vanadium, and columbium.
Claim 16
Dependent Claim
22 words
A method according to claim 13 wherein said dispersoid particles are present at an interparticle spacing of less than about 2 microns.
Claim 17
Dependent Claim
12 words
A method according to claim 17 wherein said dispersoid is titanium nitride.
Claim 18
Dependent Claim
24 words
A method according to claim 17 wherein said warm working is at a temperature which does not exceed a temperature of about 2, 100*F.
Claim 19
Dependent Claim
21 words
A method according to claim 19 wherein said warm working is at a temperature of from about 1200*F to about 2,100*F.
Claim 20
Dependent Claim
21 words
A method according to claim 19 wherein said warm working is at a temperature of from about 800*F to about 1600*F.
Claim 21
Dependent Claim
18 words
A method according to claim 17 wherein said annealing is at a temperature of at least about 2300*F.
Claim 22
Dependent Claim
18 words
A method according to claim 22 wherein said annealing is at a temperature of at least about 2400*F.
Claim 23
Dependent Claim
42 words
A method according to claim 13 wherein said dispersoid is a nitride of a metal from the group consisting of titanium, aluminum, vanadium, and columbium and wherein said dispersoid particles are present at an interparticle spacing of less than about 0.5 micron.
Claim 24
Dependent Claim
30 words
A method according to claim 13 wherein said dispersoid is titanium nitride and wherein said titanium nitride particles are present at an interparticle spacing of less than about 1 micron.
References Cited (Backward Citations)
US2703298A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |