Patent US3615924A successfully refreshed from Google Patents.
US3615924A
Expired / Lapsed
US
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Process and apparatus for surface hardening hardenable steels
Assignee: Individual
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Filing: 1968-01-26
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Granted: 1971-10-26
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Expires: 1988-01-26
Abstract
Abstract This invention relates to surface hardening hardenable steels with the plasma flame from a nozzleless plasma torch. The torch has an inner rod electrode and an outer electrode, which extends axially further than the rod electrode. A stream of ionizable gas passes through the torch and an electric arc discharge is sustained between the electrodes to create a plasma flame. The steel to be hardened is subjected to the flame to heat its surface at an extremely high rate to form metastable austenite. Then further energy is introduced, such as by mechanical shock, to transform the austenite into fine-grained martensite.
Inventors
- 👤 Karl Swoboda
- 👤 Maximilian Pater
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:17
CPC Classifications
C; C21; C21D; C21D1/00; C21D1/06; C21D1/09; Y; Y10; Y10S; Y10S148/00; Y10S148/902; Y10S148/903
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
38 words
The method as claimed in claim 1, in which said nozzleless plasma torch has an additional source of charge carriers, said charge carrier source introducing charge carriers into the plasma so as to eliminate the quasi-neutral state thereof.
Claim 2
Dependent Claim
62 words
The method as claimed in claim 2 wherein the form of the plasma flame and the rate at which energy is supplied by said flame to said surface in accordance with the configuration of the surface to be hardened is controlled by selecting a combination of the following three variables: a. current value b. gas feed rate c. nature of feed gas.
Claim 3
Dependent Claim
17 words
A process as set forth in claim 1 in which said torch is operated with alternating current.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-25 | 1975-04-26 | 1975-10-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-25 | 1979-04-26 | 1979-10-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-25 | 1983-04-26 | 1983-10-26 | $7700.00 | Window Closed / Lapsed |