US3839095A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making a drawing steel sheet by continuous annealing process including shelf treatment therein
Assignee: JFE Engineering Corp
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Filing: 1972-03-27
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Granted: 1974-10-01
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Expires: 1992-03-27
Abstract
Abstract A soft steel sheet, in which C content is 0.02 to 0.10 percent, manufactured with a continuous annealing process comprising the following steps; heating the cold reduced steel strip up to the range of recrystallization temperature to 850*C, slow-cooling from said temperature to the range of A1 point to 600*C and then rapid-cooling from said temperature to the normal temperature at a cooling rate of 200*C/sec to 10,000*C/sec, and again heating up to the range of 300*C to 530*C and keeping at said temperature for at least 10 seconds, lastly cooling to the normal temperature. Such steel sheet is economical in cost because of high productivity.
Inventors
- 👤 H Kubotera
- 👤 K Nakaoka
- 👤 K Watanabe
- 👤 T Kurihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 00:52
CPC Classifications
C; C21; C21D; C21D8/00; C21D8/02; C21D8/04; C21D8/0447; C21D8/0473; C21D8/0421; C21D8/0426
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
127 words
A METHOD OF MAKING A DRAWING STEEL SHEET COMPRISING THE FOLLOWING STEPS: MAKING A STEEL INCLUDING C CONTENT OF 0.02 TO 0.10 PERCENT, IN A CONTINUOUS ANNEALING STAGE FOLLOWING AN ORDINARY SLABBING OR CONTINUOUS CASTING, HOT-ROLLING, PICKING AND COLD-REDUCING, HEATING UP SAID COLD-REDUCED STEEL SRIP TO THE RANGE OF RECRYSTALLIZATION TEMPERATURE AND 850*C, SLOW-COOLING FROM SAID TEMPERATURE TO THE RANG OF A1 POINT AND 6000*C AND THEN RAPID-COOLING FROM SAID TEMPERATURE TO THE NORMAL TEMPERATURE BY A COOLING RATE OF 200*C/SEC AND 10,000*C/SEC, SHELF-TREATING IN WHICH SAID STRIP IS REHEATED UP TO THE RANGE OF 300*C AND 530*C, SUCCESSIVELY COOLED SLOWYL FROM SAID TEMPERATURE TO AT LEAST 300*C, AND LASTLY COOLING FROM SAID LAST MENTIONED TEMPERATURE TO THE NORMAL TEMPERATURE AND THEN TEMPER-COOLING, IN THE USUAL MANNER.
Claim 2
Independent Claim
127 words
A METHOD OF MAKING A DRAWING STEEL SHEET COMPRISING THE FOLLOWING STEPS: MAKING A STEEL INCLUDING C CONTENT OF 0.02 TO 0.10 PERCENT, IN A CONTINUOUS ANNEALING STAGE FOLLOWING AN ORDINARY SLABBING OR CONTINUOUS CASTING, HOT-ROLLING, PICKING AND COLD-REDUCING, HEATING UP SAID COLD-REDUCED STEEL SRIP TO THE RANGE OF RECRYSTALLIZATION TEMPERATURE AND 850*C, SLOW-COOLING FROM SAID TEMPERATURE TO THE RANG OF A1 POINT AND 6000*C AND THEN RAPID-COOLING FROM SAID TEMPERATURE TO THE NORMAL TEMPERATURE BY A COOLING RATE OF 200*C/SEC AND 10,000*C/SEC, SHELF-TREATING IN WHICH SAID STRIP IS REHEATED UP TO THE RANGE OF 300*C AND 530*C, SUCCESSIVELY COOLED SLOWYL FROM SAID TEMPERATURE TO AT LEAST 300*C, AND LASTLY COOLING FROM SAID LAST MENTIONED TEMPERATURE TO THE NORMAL TEMPERATURE AND THEN TEMPER-COOLING, IN THE USUAL MANNER.
Claim 3
Dependent Claim
31 words
A method of making a drawing steel sheet as set forth in claim 1 wherein coiling operation followed by said hot-rolling is carried out with a temperature of at least 630*C.
Claim 4
Dependent Claim
28 words
A method of making a drawing steel sheet as set forth in claim 1 wherein said slow-cooling rate following said heating the cold-reduced steel strip is about 5*C/sec.
Claim 5
Dependent Claim
26 words
A method of making a drawing steel sheet as set forth in claim 1 wherein said reheating temperature is within the range of 350*C and 450*C.
Claim 6
Dependent Claim
24 words
A method of making a drawing steel sheet as set forth in claim 4 wherein said slow-cooling rate following said reheating is about 12*C/sec.
Claim 7
Dependent Claim
83 words
A method of making a drawing steel sheet as set forth in claim 1 wherein said continuous annealing is carried out with which said strip is heated up at about 800*C, cooled slowly to about 650*C by the rate of 5*C/sec and then cooled rapidly from said temperature to the normal temperature by about 600*C/sec and in successive shelf treatment said strip is heated up to 530*C and 500*C and then cooled slowly to 300*C by the rate of about 12*C/sec, next air-cooled.
Claim 8
Dependent Claim
36 words
A method of making a drawing steel sheet as set forth in claim 6 wherein said continuous annealing process is carried out to the steel strip which is coiled with about 700*C in hot rolling stage.
Claim 9
Dependent Claim
22 words
A method of making a drawing steel sheet as set forth in claim 7 wherein treating steel strip is an Al-killed steel.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-30 | 1978-04-01 | 1978-10-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-30 | 1982-04-01 | 1982-10-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-30 | 1986-04-01 | 1986-10-01 | $7700.00 | Window Closed / Lapsed |