US3854932A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for production of stainless steel
Assignee: Allegheny Ludlum Corp
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Filing: 1973-06-18
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Granted: 1974-12-17
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Expires: 1993-06-18
Abstract
Abstract A process is disclosed for the production of stainless steel wherein a chromium-containing melt suitable for producing stainless steel is blown with oxygen in an oxygen converter, and an inert gas is introduced through at least one tuyere in the bottom of the converter while the interior of the converter above the liquid level is maintained at subatmospheric pressure.
Inventors
- 👤 H Bishop
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:17
CPC Classifications
C; C21; C21C; C21C7/00; C21C7/0081; C21C5/00; C21C5/005; C21C5/28; C21C5/30; C21C5/35; Y; Y02; Y02P; Y02P10/00; Y02P10/10; Y02P10/143
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
78 words
A PROCESS FOR PRODUCING STAINLESS STEEL COMPRISNG: A PROVIDING A CHARGE THT IS A LEAST PARTLY LIQUID AN SUITABLE FOR PRODUCING A CHROMIUM-CONTAINING STAINLESS STEEL IN AN OXYGEN STEEL CONVERTER HAVING A TUYRENE IN ITS BOTTOM SECTION. B. INTRODUCING OXYGEN THROUGH A LANCE ONTO OR BENEATH THE SURFACE OF SAID CHARGE, C. INTRODUCING AN INERT GAS OR AN ENDOTHEMIC GAS THROUGH SAID TUYERE, D. MAINTAINING A SUBATMOSPHERIC PRESSURE IN SAID CONVERTER, AND E. RECOVERING A STAINLESS STEEL PRODUCT.
Claim 2
Dependent Claim
78 words
A PROCESS FOR PRODUCING STAINLESS STEEL COMPRISNG: A PROVIDING A CHARGE THT IS A LEAST PARTLY LIQUID AN SUITABLE FOR PRODUCING A CHROMIUM-CONTAINING STAINLESS STEEL IN AN OXYGEN STEEL CONVERTER HAVING A TUYRENE IN ITS BOTTOM SECTION. B. INTRODUCING OXYGEN THROUGH A LANCE ONTO OR BENEATH THE SURFACE OF SAID CHARGE, C. INTRODUCING AN INERT GAS OR AN ENDOTHEMIC GAS THROUGH SAID TUYERE, D. MAINTAINING A SUBATMOSPHERIC PRESSURE IN SAID CONVERTER, AND E. RECOVERING A STAINLESS STEEL PRODUCT.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein the inert gas comprises argon introduced at a rate of about 5-100 scfm.
Claim 4
Dependent Claim
19 words
The process of claim 1 wherein the inert gas is introduced at a pressure of at least 100 psi.
Claim 5
Dependent Claim
32 words
The process of claim 1 wherein the tuyere is substantially on the diameter of the converter bottom that lies in the same plane as the horizontal axis of rotation of the converter.
Claim 6
Dependent Claim
19 words
The process of claim 1 wherein the pressure maintained in said converter is at most 100 mm Hg absolute.
Claim 7
Dependent Claim
31 words
The process of claim 1 wherein the stainless steel product contains less than 0.02 percent w carbon, and the final pressure in said converter is at most 20 mm Hg absolute.
Claim 8
Dependent Claim
29 words
The process of claim 1 wherein, subsequent to the introduction of oxygen but prior to recoveriNg a product, the contents of said converter are contacted with a reducing slag.
Claim 9
Dependent Claim
16 words
The process of claim 1 wherein oxygen is introduced through said lance at progressively diminishing rates.
Claim 10
Dependent Claim
14 words
The process of claim 1 wherein the pressure in said converter is progressively diminished.
Claim 11
Dependent Claim
43 words
The process of claim 1 wherein said inert gas is argon, and it is introduced through said tuyere after oxygen introduction is terminated and while a subatmospheric pressure is maintained in said converter, whereby the nitrogen content of the stainless steel is diminished.
Claim 12
Dependent Claim
12 words
The process of claim 1 wherein said endothermic gas is water vapor.
Claim 13
Dependent Claim
12 words
The process of claim 1 wherein said endothermic gas is carbon dioxide.
Claim 14
Dependent Claim
23 words
The process of claim 1 wherein said inert gas or endothermic gas is introduced through a plurality of tuyeres in the bottom section.
References Cited (Backward Citations)
US3320053A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-16 | 1978-06-17 | 1978-12-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-16 | 1982-06-17 | 1982-12-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-16 | 1986-06-17 | 1986-12-17 | $7700.00 | Window Closed / Lapsed |