Patent US3615348A successfully refreshed from Google Patents.
US3615348A
Expired / Lapsed
US
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Stainless steel melting practice
Assignee: Armco Inc
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Filing: 1968-07-31
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Granted: 1971-10-26
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Expires: 1988-07-31
Abstract
Abstract Melting a charge comprising alloys of iron and chromium in an electric arc furnace to achieve metal of maximum cleanliness with minimum oxide inclusions but of high-carbon content, and then ridding the metal of carbon in a vacuum furnace by way of readily reducible oxides and low pressure.
Inventors
- 👤 Harry Tanczyn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:47
CPC Classifications
C; C21; C21C; C21C5/00; C21C5/52; C21C5/5264; C21C7/00; C21C7/10; Y; Y02; Y02P; Y02P10/00; Y02P10/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
In the production of stainless steel containing about 10% to 35% to more chromium and of low-carbon content the art which comprises melting in an electric arc furnace a charge comprising at least one of the following two ingredients stainless steel scrap and high-carbon ferrochromium, yielding a melt of desirably high chromium and low chromium oxide contents but undesirably high-carbon content; and thereafter treating the melt in a vacuum induction furnace with one or more of the oxides of nickel, cobalt, molybdenum, chromium, copper, iron, manganese, silicon and titanium at temperatures of at least about 2,900* F. and under pressures brought to a value not exceeding several millimeters of mercury to eliminate carbon.
Claim 2
Dependent Claim
40 words
A process according to claim 1 in which the melt of undesirably high-carbon content is treated with a reducible oxide under pressures brought to a value not exceeding several millimeters of mercury and temperatures of at least about 2,950* F.
Claim 3
Dependent Claim
104 words
In the production of stainless steel containing about 10% to 35% or more chromium and with nickel up to 35% or more the art whIch comprises melting a charge comprising iron and chromium in an electric arc furnace to form a melt of substantial chromium and desirably low chromium oxide content but undesirably high-carbon content at temperatures not exceeding about 3,000* F.; and thereinafter a vacuum the melt, in a vacuum induction furnace with nickel oxide at temperatures of at least about 2,950* F. and pressures brought to a value not exceeding several millimeters of mercury to eliminate carbon in the presence of chromium.
Claim 4
Dependent Claim
124 words
In the production of a chromium-nickel stainless steel containing about 10% to 35% or more chromium and with nickel up to 35% or more the art which comprises melting in an electric arc furnace a charge comprising at least one of the following two ingredients stainless steel scrap and high-carbon ferrochromium, forming a melt of undesirably high-carbon content but desirably low chromium oxide content at temperatures not exceeding about 3, 000* F.; maintaining the melt under a slag of lime and ferrosilicon at such temperatures to eliminate sulphur; and thereafter ridding the melt of carbon by treating the same, in a vacuum induction furnace, with nickel oxide under conditions of high-temperature and under pressure brought to a value not exceeding 1 millimeter of mercury.
Claim 5
Dependent Claim
104 words
In the production of stainless steel containing about 10% to 35% or more chromium the art which comprises melting in an electric arc furnace having carbon electrodes a charge comprising stainless steel scrap and high-carbon ferrochromium, yielding a melt of substantial chromium content but desirably low chromium oxide content and undesirably high-carbon content at temperatures not exceeding about 3,000* F.; and thereafter treating the melt, in a vacuum induction furnace, with iron oxide at temperatures of about 2,900* F. to about 3,000* F. and under conditions of pressure brought to a value not exceeding several millimeters of mercury to rid the same of carbon.
Claim 6
Dependent Claim
85 words
In the production of stainless steel containing about 10% to 35% or more chromium the art which comprises melting a charge comprising stainless steel scrap in an electric arc furnace at moderate melting temperature, giving a melt of undesirably high carbon content but desirably low chromium oxide content; and thereafter treating the melt, in a vacuum induction furnace, with a reducible oxide at temperatures of about 2,950* F. to about 3, 000* F. and pressures brought to a value not exceeding several millimeters of mercury.
Claim 7
Dependent Claim
95 words
In the production of stainless steel containing about 10% to 35% or more chromium and with nickel up to 35% or more the art which comprises melting, in an electric arc furnace a charge comprising stainless steel scrap and high-carbon ferrochromium, yielding metal of substantial chromium content but desirably low chromium oxide content and undesirably high-carbon content; and treating the same, in a vacuum induction furnace with nickel oxide at temperatures of at least about 2,950* F. and pressures brought to a value not exceeding 1 millimeter of mercury to rid the metal of carbon.
Claim 8
Dependent Claim
80 words
In the production of stainless steel containing about 10% to 35% or more chromium the art which comprises melting in an electric arc furnace a charge comprising iron and chromium, yielding metal of undesirably high-carbon content, but desirably low chromium oxide content; and treating the metal, in a vacuum induction furnace, with iron oxide at temperatures of at least about 2,950* F. and pressures brought to a value not exceeding 1 millimeter of mercury to rid the same of carbon.
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 |