US3971676A
Expired / Lapsed
US
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Magnetic material of high strength and toughness
Assignee: Licentia Patent Verwaltungs GmbH
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Filing: 1971-04-19
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Granted: 1976-07-27
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Expires: 1991-04-19
Abstract
Abstract A steel hardening by precipitation in a martensitic matrix and having an iron-nickel, iron-chromium, or iron-manganese basis is austenitized and then subjected to a heat treatment including heating it to at least 500°C. This hardens the steel and at the same time increases its coercive force.
Inventors
- 👤 Klaus Detert
- 👤 Hans-Jochen Lipp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:52
CPC Classifications
C; C22; C22C; C22C38/00; C22C38/10; C22C38/105; H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
134 words
A method for preparing a magnetic material suitable for use in rotors in hysteresis motors operating at high r.p.m. from a martensitically hardening steel consisting essentially of at least about 65% iron and a member of the group of 8 to 25% Ni, 5 to 20% Cr, and 1 to 10% Mn, said rotor having high stability and toughness and increased coercive field strength, comprising the steps of treating the steel by austenitizing said steel and then subjecting it to a heat treatment including heating the steel to at least 500°C for a time sufficient to yield a coercive force, H c , of at least 40 oersteds and provide a tensile strength of at least about 150 kiloponds/mm 2 and a toughness as measured by a reduction in area of at least 15%.
Claim 2
Independent Claim
134 words
A method for preparing a magnetic material suitable for use in rotors in hysteresis motors operating at high r.p.m. from a martensitically hardening steel consisting essentially of at least about 65% iron and a member of the group of 8 to 25% Ni, 5 to 20% Cr, and 1 to 10% Mn, said rotor having high stability and toughness and increased coercive field strength, comprising the steps of treating the steel by austenitizing said steel and then subjecting it to a heat treatment including heating the steel to at least 500°C for a time sufficient to yield a coercive force, H c , of at least 40 oersteds and provide a tensile strength of at least about 150 kiloponds/mm 2 and a toughness as measured by a reduction in area of at least 15%.
Claim 3
Dependent Claim
23 words
A method as claimed in claim 1, said steel consisting essentially of 12 to 20% Ni, 5 to 20% Co, and remainder Fe.
Claim 4
Dependent Claim
30 words
A method as claimed in claim 1, said steel further containing at least one element selected from the group consisting of titanium, niobium, molybdenum, tungsten, tantalum, vanadium, beryllium, and aluminum.
Claim 5
Dependent Claim
59 words
A method as claimed in claim 1, said steel having substantially the following composition: C less than 0.03%, 4 to 6% Mo, 15 to 18% Ni, 8 to 12% Co, and 0.3 to 0.8% Ti; the step of austenitizing being substantially for 1 hour at 810°C; the step of subjecting being a heating substantially for 30 minutes at 600°C.
Claim 6
Dependent Claim
65 words
A method as claimed in claim 1, said steel having substantially the following composition: C less than 0.03%, 4 to 6% Mo, 15 to 18% Ni, 8 to 12% Co, and 0.3 to 0.8% Ti; the step of austenitizing being substantially for 1 hour at 810°C; the step of subjecting being heat treating substantially for 45 minutes at 600°C and for 16 hours at 45°C.
Claim 7
Dependent Claim
70 words
A method as claimed in claim 1, said steel having substantially the following composition: C less than 0.03% 4 to 6%, Mo, 15 to 18% Ni, 8 to 12% Co, and 0.3 to 0.8% Ti; the step of austenitizing being substantially for 1 hour at 70°C; the step of subjecting being heat treating substantially for 2 hours at 650°C, for 30 minutes at 810°C, and for 3 hours at 480°C.
Claim 8
Dependent Claim
11 words
A magnetic material produced according to the process of claim 1.
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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) | 1979-07-27 | 1980-01-26 | 1980-07-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-07-27 | 1984-01-26 | 1984-07-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-07-27 | 1988-01-26 | 1988-07-27 | $7700.00 | Window Closed / Lapsed |