US3615903A
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High-purity ferrous material and method of making it
Assignee: Armco Inc
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Filing: 1968-10-03
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Granted: 1971-10-26
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Expires: 1988-10-03
Abstract
Abstract A high-purity ferrous material and method of making it, whereby the ferrous material is hot rolled to sheet or coil thicknesses. Thereafter, the ferrous material is descaled and may be further reduced in thickness by cold rolling when necessary. The hot rolled or hot and cold rolled ferrous material is then coated with any of the annealing separators described below and annealed at a temperature of from about 1,900* F. to about 2,500* F. in an atmosphere of 100 percent hydrogen or a hydrogen bearing atmosphere capable of removing impurities to the desired low levels. When the proper relationships are maintained with respect to initial manganese and sulfur contents, gauge, nature of the annealing separator, dew point of the annealing atmosphere, composition of the annealing atmosphere, annealing temperature and soak time, a product is produced having a composition comparing favorably to or surpassing that of typical electrolytic iron.
Inventors
- 👤 D Cameron Perry
- 👤 Stephen W Zeller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:26
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/68; C21D1/70; C21D1/74; C21D8/00; C21D8/02; C21D8/0278; C21D8/0284; C21D8/12; C21D8/1277; C21D8/1283; C21D8/0247; C21D8/0257; Y; Y02; Y02P; Y02P10/00; Y02P10/10; Y02P10/122
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
16 words
The process claimed in claim 1 wherein said initial manganese content is below about 0.06 percent.
Claim 2
Dependent Claim
24 words
The process claimed in claim 1 wherein said stock is reduced to a final gauge of from about 0.025 inches to about 0.080 inches.
Claim 3
Dependent Claim
24 words
The process claimed in claim 1 wherein said anneal is conducted at a temperature of from about 2,100* F. to about 2, 200* F.
Claim 4
Dependent Claim
25 words
The process claimed in claim 1 wherein said annealing separator is chosen from the class consisting of calcium oxide, magnesia, lime, dolomite and combinations thereof.
Claim 5
Dependent Claim
12 words
The process claimed in claim 1 wherein said annealing separator is alumina.
Claim 6
Dependent Claim
14 words
The process claimed in claim 1 wherein said annealing separator is a mechanical separator.
Claim 7
Dependent Claim
24 words
The process claimed in claim 1 wherein said dew point of said annealing atmosphere is maintained at a level of 30* F. or less.
Claim 8
Independent Claim
161 words
A method of producing high-purity ferrous stock from a starting material chosen from the class consisting of ingot iron and plain carbon steel having an initial manganese content up to about 0.5 percent, comprising the steps of reducing the thickness of said stock to a final gauge of at least 0.2 inches, descaling said stock, applying an annealing separator to said stock, annealing said stock in an atmosphere of 100 percent hydrogen or a denitriding hydrogen bearing atmosphere, conducting said anneal at a temperature of from about 1,900* F. to about 2,500* F., maintaining the dew point of said annealing atmosphere at a level such as to prevent the formation of iron oxide at the surfaces of said stock, and maintaining said stock at temperature for from about 24 hours to about 140 hours, whereby to produce a ferrous stock having a final sulfur content of about 0.004 percent or less and a final nitrogen content of 0.004 percent or less.
Claim 9
Independent Claim
163 words
A method of producing high-purity ferrous stock from ingot iron having an initial manganese content up to about 0.06 percent, comprising the steps of reducing the thickness of said ingot iron to a final gauge of from about 0.025 inches to about 0.080 inches, descaling said ingot iron, applying to said ingot irons an annealing separator chosen from the class consisting of calcium oxide, magnesia, lime, dolomite and combinations thereof, annealing said ingot iron in an atmosphere of 100 percent hydrogen, or a hydrogen-bearing atmosphere having a nitrogen content such as to prevent nitrogen pickup by said stock, conducting said anneal at a temperature of from about 2,100* F. to about 2,200* F., maintaining the dew point of said annealing atmosphere at a level of 30* F. or less and maintaining said ingot iron at temperature for a time of from 24 hours to 140 hours whereby to produce a ferrous stock having a final sulfur content of about 0.004 percent or less.
Claim 10
Dependent Claim
60 words
A high-purity, hot rolled ferrous material having a sulfur Content of up to about 0.004 percent, a nitrogen content of up to about 0.004 percent, a phosphorous content of up to about 0.005 percent, an oxygen content of up to about 0.070 percent and a carbon content of up to about 0.018 percent, produced by the process of claim 1.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-25 | 1975-04-26 | 1975-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-25 | 1979-04-26 | 1979-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-25 | 1983-04-26 | 1983-10-26 | $7700.00 | Window Closed / Lapsed |