US3873377A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for improving batch annealed strip surface quality
Assignee: Bethlehem Steel Corp
•
Filing: 1973-11-21
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Granted: 1975-03-25
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Expires: 1993-11-21
Abstract
Abstract A process is described for eliminating surface discoloration of batch annealed steel products, where said discoloration has been described as graphite staining. Said process is characterized by an annealing step which includes the introduction of a small quantity of CO2 to the annealing atmosphere comprising hydrogen and nitrogen.
Inventors
- 👤 Thomas W Fisher
- 👤 Edward D Melcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:44
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/74; C21D1/76
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
75 words
A PROCESS OF ANNEALING A COIL OF STEEL STRIP, WHERE ADJACENT CONVOLUTION THEREOF AREIN CONTACT WITH ONE ANOTHER COMPRISING THE STEPS OF PLACING SAID COILL IN AN ENCLOSURE INTRODUCING INTO SAID ENCLOSURE A NON-OXIDING GAS CONSISTING OF, BY VOLUME, HYDROGEN IN AN AMOUNT BETWEEN ABOUT 45% TO ABOUT 25%, ABOUT 3% TO ABOUT 9% CARBON DIOXIDE, BALANCE NITROGEN, AND HEATING SAID COIL IN SAID NON-OXIDIZING GAS TO A TEMPERATURE BETWEEN ABOUT 1100*F. TO ABOUT 1300*F.
Claim 2
Dependent Claim
75 words
A PROCESS OF ANNEALING A COIL OF STEEL STRIP, WHERE ADJACENT CONVOLUTION THEREOF AREIN CONTACT WITH ONE ANOTHER COMPRISING THE STEPS OF PLACING SAID COILL IN AN ENCLOSURE INTRODUCING INTO SAID ENCLOSURE A NON-OXIDING GAS CONSISTING OF, BY VOLUME, HYDROGEN IN AN AMOUNT BETWEEN ABOUT 45% TO ABOUT 25%, ABOUT 3% TO ABOUT 9% CARBON DIOXIDE, BALANCE NITROGEN, AND HEATING SAID COIL IN SAID NON-OXIDIZING GAS TO A TEMPERATURE BETWEEN ABOUT 1100*F. TO ABOUT 1300*F.
Claim 3
Dependent Claim
21 words
The process according to calim 1 wherein said carbon dioxide is present in an amount between about 4% to about 8%.
Claim 4
Dependent Claim
21 words
The process according to calim 1 wherein said carbon dioxide is present in an amount between about 4% to about 8%.
Claim 5
Dependent Claim
37 words
The process according to claim 1 wherein said coil is soaked at the temperature between about 1100* F. to about 1300* F., and said non-oxidizing gas is maintained for at least the time during the soaking period.
References Cited (Backward Citations)
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US2304518A
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US2402013A
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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) | 1978-03-24 | 1978-09-23 | 1979-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-24 | 1982-09-23 | 1983-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-24 | 1986-09-23 | 1987-03-25 | $7700.00 | Window Closed / Lapsed |