Patent US3874950A successfully refreshed from Google Patents.
US3874950A
Expired / Lapsed
US
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Processing of steel bars after hot rolling
Assignee: BAR ACQUISITION COMPANY 410 OBERLIN AVE SW MASSILLON OH 44647 A CORP OF
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Filing: 1971-02-23
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Granted: 1975-04-01
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Expires: 1991-02-23
Abstract
Abstract Steel bars are rapidly cooled from hot rolling temperature to a temperature of about 1,500* F. and are then cooled at a much lower rate to a temperature below their lower transformation temperature to minimize their compressive flow strength and improve their cold-heading and forming properties.
Inventors
- 👤 John David Grozier
- 👤 John Ray Bell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 18:36
CPC Classifications
C; C21; C21D; C21D9/00; C21D9/52; C21D9/525; C21D1/00; C21D1/84
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
117 words
THE METHOD OF PROCESSING STEEL BARS OF COLD-HEADING GRADE IMMEDIATELY AFTER HOT ROLLING TO PRODUCE OPTIMUM COLDHEADING PROPERTIES, THE HOT-ROLLING FINISHING TEMPERATURE BEING ABOUT 1,500*F, INCLUDING A FAST COOLING STEP FOLLOWED BY A SLOW COOLING STEP, THE FAST COOLING STEP COMPRISING COOLING THE HOT BAR TO A TEMPERATURE NOT GREATER THAN ABOUT 1,500*F, BUT ABOVE ITS LOWER TRANSFORMATION TEMPERATURE AT A COOLING RATE NOT LESS THAN ABOUT 300*F, PER MINUTE BUT NOT GREAT ENOUGH TO FORM BAINITE OR MARTENSITE AT THE BAR SURFACE, AND THE SLOW COOLING STEP COMPRISING COOLING THE BAR THROUGH ITS LOWER TRANSFORMATION TEMPERATURE TO A TEMPERATURE OF NOT MORE THAN ABOUT 1,200*F. AT A COOLING RATE NOT GREATER THAN ABOUT 10*F. PER MINUTE.
Claim 2
Independent Claim
117 words
THE METHOD OF PROCESSING STEEL BARS OF COLD-HEADING GRADE IMMEDIATELY AFTER HOT ROLLING TO PRODUCE OPTIMUM COLDHEADING PROPERTIES, THE HOT-ROLLING FINISHING TEMPERATURE BEING ABOUT 1,500*F, INCLUDING A FAST COOLING STEP FOLLOWED BY A SLOW COOLING STEP, THE FAST COOLING STEP COMPRISING COOLING THE HOT BAR TO A TEMPERATURE NOT GREATER THAN ABOUT 1,500*F, BUT ABOVE ITS LOWER TRANSFORMATION TEMPERATURE AT A COOLING RATE NOT LESS THAN ABOUT 300*F, PER MINUTE BUT NOT GREAT ENOUGH TO FORM BAINITE OR MARTENSITE AT THE BAR SURFACE, AND THE SLOW COOLING STEP COMPRISING COOLING THE BAR THROUGH ITS LOWER TRANSFORMATION TEMPERATURE TO A TEMPERATURE OF NOT MORE THAN ABOUT 1,200*F. AT A COOLING RATE NOT GREATER THAN ABOUT 10*F. PER MINUTE.
Claim 3
Dependent Claim
34 words
The method of claim 1 in which the hot bar is coiled at the conclusion of the fast cooling step and the slow cooling step is carried out with the bar in coil form.
Claim 4
Dependent Claim
50 words
The method of claim 1 in which the slow cooling step is accomplished by passing the bar in strand form through a zone of temperature decreasing from a value above the lower transformation temperature at its entry end to a value below the lower transforMation temperature at its exit end.
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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |