US3666569A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Production of deep drawing steel
Assignee: Republic Steel Corp
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Filing: 1969-06-18
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Granted: 1972-05-30
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Expires: 1989-06-18
Abstract
Abstract DEEP-DRAWABLE, ALUMINUM-KILLED STEEL SHEET IS PRODUCED TO BE SUBSTANTIALLY NON-EARING BY PROCEDURE WHEREIN AFTER HOT ROLLING TO A FINISH TEMPERATURE OF AT LEAST ABOUT 1500* F. AND COILING AT A TEMPERATURE NOT HIGHER THAN ABOUT 1100*F., THE STEEL IS COLD REDUCED BY AN AMOUNT BETWEEN ABOUT 50% AND 80% AND THEN ANNEALEDX BY A FIRST STEP OF HEATING TO A TEMPERATURE IN THE RANGE BETWEEN ABOUT 1030* F. AND 1090*F. FOR AT LEAST TWO HOURS, ADVANTAGEOUSLY SIX HOURS, AND THEN HEATING THE SHEET TO A TEMPERATURE BELOW THE LOWER CRITICAL POINT, FOR SOFTENING.
Inventors
- 👤 Frank A Hultgren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:22
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/001; C21; C21D; C21D8/00; C21D8/02; C21D8/04; C21D8/0447; C21D8/0473; C21D8/0421; C21D8/0426; C21D8/0436
Claims Analysis
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References Cited (Backward Citations)
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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) | 1975-05-30 | 1975-11-29 | 1976-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-30 | 1979-11-29 | 1980-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-30 | 1983-11-29 | 1984-05-30 | $7700.00 | Window Closed / Lapsed |