US4247326A
Expired / Lapsed
US
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Free machining steel with bismuth
Assignee: Inland Steel Co
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Filing: 1979-08-29
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Granted: 1981-01-27
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Expires: 1999-08-29
Abstract
Abstract A free machining steel shape containing bismuth which functions as a liquid metal embrittler. The opportunity for bismuth to function as a liquid metal embrittler is increased by limiting the size of bismuth-containing inclusions to less than five microns.
Inventors
- 👤 Dennis T. Quinto
- 👤 Debanshu Bhattacharya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:10
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/60
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
94 words
In a free machining cast steel shape consisting essentially of, in wt.%, ______________________________________
carbon 0.06-1.0
manganese 0.3-1.6
silicon 0.30 max.
sulfur 0.03-0.50
phosphorous 0.12 max.
bismuth 0.05-0.40
iron essentially the balance.
______________________________________ the improvement wherein: said bismuth is present in bismuth-containing inclusions having a mean size less than 5 microns, to increase the number of locations in the microstructure of said steel where bismuth is available for immediate transport to the tip of a microcrack during a machining operation, compared to a steel having the same amount of bismuth in inclusions of larger size.
Claim 2
Dependent Claim
94 words
In a free machining cast steel shape consisting essentially of, in wt.%, ______________________________________
carbon 0.06-1.0
manganese 0.3-1.6
silicon 0.30 max.
sulfur 0.03-0.50
phosphorous 0.12 max.
bismuth 0.05-0.40
iron essentially the balance.
______________________________________ the improvement wherein: said bismuth is present in bismuth-containing inclusions having a mean size less than 5 microns, to increase the number of locations in the microstructure of said steel where bismuth is available for immediate transport to the tip of a microcrack during a machining operation, compared to a steel having the same amount of bismuth in inclusions of larger size.
Claim 3
Dependent Claim
22 words
In a free machining cast steel shape as recited in claim 1 wherein: said bismuth is present as inclusions containing elemental bismuth.
Claim 4
Dependent Claim
28 words
In a free machining cast steel shape as recited in claim 1 wherein said steel further comprises up to 0.3 wt.% lead and up to 0.06 wt.% tellurium.
Claim 5
Dependent Claim
24 words
In a free machining cast steel shape as recited in claim 1 wherein said manganese content is greater than three times the sulfur content.
Claim 6
Dependent Claim
18 words
In a free machining cast steel shape as recited in claim 1 wherein said shape is an ingot.
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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) | 1984-01-27 | 1984-07-28 | 1985-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-27 | 1988-07-28 | 1989-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-27 | 1992-07-28 | 1993-01-27 | $7700.00 | Window Closed / Lapsed |