US4394192A
Expired / Lapsed
US
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Method for producing low silicon steel electrical lamination strip
Assignee: Inland Steel Co
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Filing: 1981-07-02
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Granted: 1983-07-19
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Expires: 2001-07-02
Abstract
Abstract The chemical composition and processing of a cold rolled steel strip are controlled. Laminations for the core of an electric motor are stamped from the strip and decarburized to produce a lamination having a 1.5 T (15 kG) average core loss value less than about 5.70 W/kg (2.60 W/lb.) and average peak permeability substantially more than about 2000 G/Oe. for a sample thickness of about 0.018 in. (0.46 mm.).
Inventors
- 👤 Prabhat K. Rastogi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:49
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/12; H01F1/14; H01F1/147; H01F1/14766; H01F1/14775; C; C21; C21D; C21D8/00; C21D8/12; C21D8/1216; C21D8/1222; C21D8/1233; C21D8/1244; C21D8/1266
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
194 words
In a method for producing cold rolled steel strip for use in electric motor laminations, the steps of: providing a steel consisting essentially of the following composition in wt.% before cold rolling: ______________________________________
carbon .06 max.
manganese .55-.75
silicon .15-.25
aluminum .15-.25
phosphorus .12 max.
sulfur .025 max.
iron essentially the balance;
______________________________________ hot rolling said steel into steel strip; coiling said hot rolled steel strip while the steel is at a coiling temperature in the range 1250°-1400° F. (682°-760° C.) and then allowing said coiled strip to cool; cold rolling said steel strip; continuously annealing said steel strip at a strip temperature in the range 1250°-1400° F. (682°-760° C.) for about 2-5 minutes, and then allowing said strip to cool; and temper rolling said strip to produce a reduction of about 5-7.5%; whereby said steel strip, after said temper rolling step, has a grain size and crystallographic orientation which, upon subsequent magnetic annealing at a temperature in the range 1400°-1550° F. (760°-843° C.) for about 1-2 hours in a decarburizing atmosphere, produces an average ferritic grain size of about 3.5-5.0 ASTM and a preponderance of crystallographic planes containing the easiest direction of magnetization.
Claim 2
Dependent Claim
194 words
In a method for producing cold rolled steel strip for use in electric motor laminations, the steps of: providing a steel consisting essentially of the following composition in wt.% before cold rolling: ______________________________________
carbon .06 max.
manganese .55-.75
silicon .15-.25
aluminum .15-.25
phosphorus .12 max.
sulfur .025 max.
iron essentially the balance;
______________________________________ hot rolling said steel into steel strip; coiling said hot rolled steel strip while the steel is at a coiling temperature in the range 1250°-1400° F. (682°-760° C.) and then allowing said coiled strip to cool; cold rolling said steel strip; continuously annealing said steel strip at a strip temperature in the range 1250°-1400° F. (682°-760° C.) for about 2-5 minutes, and then allowing said strip to cool; and temper rolling said strip to produce a reduction of about 5-7.5%; whereby said steel strip, after said temper rolling step, has a grain size and crystallographic orientation which, upon subsequent magnetic annealing at a temperature in the range 1400°-1550° F. (760°-843° C.) for about 1-2 hours in a decarburizing atmosphere, produces an average ferritic grain size of about 3.5-5.0 ASTM and a preponderance of crystallographic planes containing the easiest direction of magnetization.
Claim 3
Dependent Claim
42 words
In a method as recited in claim 1 wherein: said steel consists essentially of the following composition in wt.% before cold rolling: ______________________________________
carbon .05 max.
manganese .60-.70
silicon .18-.22
aluminum .18-.22
phosphorus .7-.10
sulfur .020 max.
iron essentially the balance.
______________________________________
Claim 4
Dependent Claim
24 words
In a method as recited in claim 1 wherein: said coiling step is performed at a temperature in the range 1300°-1350° F. (704°-732° C.).
Claim 5
Dependent Claim
20 words
In a method as recited in claim 1 wherein: said cold rolling step produces a cold reduction of about 65-80%.
Claim 6
Dependent Claim
26 words
In a method as recited in claim 1 wherein: said steel strip is continuously annealed at a strip temperature in the range 1300°-1350° F. (704°-732° C.).
Claim 7
Dependent Claim
23 words
In a method as recited in claim 5 wherein: said steel strip is continuously annealed at said strip temperature for about 2.5-3.5 minutes.
Claim 8
Dependent Claim
19 words
In a method as recited in claim 1 wherein: said temper rolling step produces a reduction of about 6-7%.
Claim 9
Dependent Claim
110 words
In a method as recited in claim 1 wherein: said steel consists essentially of the following composition in wt.% before cold rolling: ______________________________________
carbon .05 max.
manganese .60-.70
silicon .18-.22
aluminum .18-.22
phosphorus .07-.10
sulfur .020 max.
iron essentially the balance;
______________________________________ said coiling step is performed at a temperature in the range 1300°-1350° F. (704°-732° C.); said cold rolling step produces a cold reduction of about 65-80%; said steel strip is continuously annealed at a strip temperature in the range 1300°-1350° F. (704°-732° C.); said steel strip is continuously annealed at said strip temperature for about 2.5-3.5 minutes; and said temper rolling step produces a reduction of about 6-7%.
Claim 10
Dependent Claim
96 words
In combination with the method steps recited in claim 1, the additional steps for producing said electric motor laminations, said additional steps comprising: stamping electric motor laminations from said steel strip after the latter has been temper rolled; and then magnetic annealing said laminations at a temperature in the range 1400°-1550° F. (760°-843° C.) for about 1-2 hours in a decarburizing atmosphere to reduce the carbon content to less than about 0.006 wt.% and produce an average ferritic grain size of about 3.5-5.0 ASTM and a preponderance of crystallographic planes containing the easiest direction of magnetization.
Claim 11
Dependent Claim
24 words
The combination of steps recited in claim 9 wherein: said magnetic annealing step is conducted at a temperature substantially below 1550° F. (843° C.).
Claim 12
Dependent Claim
48 words
The combination of steps recited in claim 9 wherein: said laminations have a 1.5 T (15 kG) average core loss value less than about 5.70 W/kg (2.60 w/lb.) and average peak permeability substantially more than about 2000 G/Oe. for a sample thickness of about 0.018 in. (0.46 mm.).
References Cited (Backward Citations)
US2287467A
Cited
US2303343A
Cited
US3180767A
Cited
US3188250A
Cited
US3971678A
Cited
US3933537A
Cited
US3855021A
Cited
US3867211A
Cited
US3960616A
Cited
US4204890A
Cited
US4306922A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-07-18 | 1987-01-17 | 1987-07-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-07-18 | 1991-01-17 | 1991-07-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-07-18 | 1995-01-17 | 1995-07-19 | $7700.00 | Window Closed / Lapsed |