US3673094A
Expired / Lapsed
US
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Chemical milling method and bath for steel
Assignee: Armco Inc
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Filing: 1969-07-07
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Granted: 1972-06-27
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Expires: 1989-07-07
Abstract
Abstract Chemical milling of stainless steel and high nickel alloys by immersing the same in a bath of 3 to 15 percent by volume sulphuric acid, 3 to 15 percent hydrochloric acid, 2 to 6 percent nitric acid, 0.1 to 5 percent lignin, more particularly a vegetable tannin, as an inhibitor, and remainder water; and maintaining the steel or alloy in the bath at such temperature and for such time as to remove a desired quantity of metal. A best combination of results is had with the extract of the bark of Acacia Mollissima serving as the inhibitor. In milling martensitic and ferritic stainless steel, the bath additionally may contain phosphoric acid. And in milling austenitic stainless steel, the bath additionally may contain hydrofluoric acid.
Inventors
- 👤 John F Kreml
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:12
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/28
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
83 words
In the chemical milling of martensitic and ferritic stainless steels, the art which comprises immersing the steel in a bath essentially consisting of about 10 percent by volume sulphuric acid, about 10 percent hydrochloric acid, about 3 percent nitric acid, about 2 percent extract of Acacia Mollissima bark, and remainder water; and maintaining said steel in said bath at such temperature and for such time as to remove a desired quantity of metal and give a micro-roughened surface with minimum discontinuity and pitting.
Claim 2
Dependent Claim
88 words
In the chemical milling of martensitic, ferritic and precipitation-hardenable stainless steels, the art which comprises immersing the steel in a bath essentially consisting of about 7 percent by volume sulphuric acid, about 7 percent hydrochloric acid, about 2 percent to about 3 percent nitric acid, about 2 percent extract of Acacia Mollissima bark, and remainder water; and maintaining said steel in said bath at such temperature and for such time as to remove a desired quantity of metal and give a micro-roughened surface with minimum discontinuity and pitting.
Claim 3
Dependent Claim
91 words
In the chemical milling of martensitic, ferritic and precipitation-hardenable stainless steels, the art which comprises immersing the steel in a bath essentially consisting of about 5 percent by volume sulphuric acid, about 5 percent hydrochloric acid, about 4 percent nitric acid, about 4 percent phosphoric acid, about 2 percent extract of Acacia Mollissima bark, and rEmainder water; and maintaining said steel in said bath at such temperature and for such period of time as to remove a desired quantity of metal and give a micro-roughened surface with minimum discontinuity and pitting.
Claim 4
Dependent Claim
93 words
In the chemical milling of the austenitic stainless steels and nickel alloys, the art which comprises immersing the steel or alloy in a bath essentially consisting of about 5 percent by volume sulphuric acid, about 5 percent hydrochloric acid, about 4 percent nitric acid, about 4 percent hydrofluoric acid, about 2 percent extract of Acacia Mollissima bark, and remainder water; and maintaining said steel or alloy in said bath at such temperature for such time as to remove a desired quantity of metal and give a micro-roughened surface with minimum discontinuity and pitting.
Claim 5
Dependent Claim
18 words
Chemical milling according to claim 1 wherein the aqueous bath is contained in a wooden tank or vat.
Claim 6
Dependent Claim
46 words
Chemical milling according to claim 1 in which steel or alloy wire coil is maintained in the bath, with at least one intermediate withdrawal and moving about, at a temperature of 175* to 195* F. for a total period of about 4 minutes to 30 minutes.
Claim 7
Dependent Claim
62 words
Chemical milling of martensitic and ferritic stainless steels according to claim 1 wherein the bath essentially consists of about 5 percent to about 12 percent sulphuric acid by volume, about 5 percent to about 12 percent hydrochloric acid, about 2 percent to about 4 percent nitric acid, about 1 percent to about 3 percent extract of Acacia Mollissima bark, and remainder water.
Claim 8
Dependent Claim
50 words
Chemical milling bath essentially consisting of about 3 percent to about 15 percent by volume sulphuric acid, about 3 percent to about 15 percent hydrochloric acid, about 2 percent to about 6 percent nitric acid, about 0.1 percent to about 5 percent extract of Acacia Millissima bark, and remainder water.
Claim 9
Dependent Claim
36 words
Bath according to claim 9 essentially consisting of about 7 percent by volume sulphuric acid, about 7 percent hydrochloric acid, about 2 percent nitric acid, about 2 percent extract of Acacia Millissima bark, and remainder water.
Claim 10
Dependent Claim
39 words
Chemical milling bath essentially consisting of about 5 percent by volume sulphuric acid, about 5 percent hydrochloric acid, about 4 percent nitric acid, about 4 percent hydrofluoric acid, about 2 percent extract of Acacia Mollissima bark, and remainder water.
Claim 11
Dependent Claim
43 words
Chemical milling bath essentially consisting of about 5 percent by volume sulphuric acid, about 5 percent hydrochloric acid, about 4 percent nitric acid, about 4 percent phosphoric acid, about 1 percent to about 3 percent extract of Acacia Mollissima bark, and remainder water.
References Cited (Backward Citations)
US2662814A
Cited
US3349037A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |