US3634147A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Corrosion resistant tin-free steel and method for producing same
Assignee: United States Steel Corp
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Filing: 1969-11-20
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Granted: 1972-01-11
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Expires: 1989-11-20
Abstract
Abstract A superior corrosion-resistant tin-free steel is produced by vacuum depositing high-purity metallic chromium onto a thoroughly cleaned steel surface at a temperature within the range 500*1,000* F., and thereafter, before the coated steel is cooled, exposing the freshly deposited coating to an oxidizing atmosphere while the steel is at a temperature of 600* to 1,000* F. The resulting vigorous high-temperature oxidation of exposed steel at cracks and pores to magnetite produces a continuous pore-free and crack-free coating which is lustrous and metallic in appearance and provides exceptional resistance to corrosion.
Inventors
- 👤 Lawrence E Heiwig
- 👤 Leon L Lewis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 03:43
CPC Classifications
C; C23; C23C; C23C8/00; C23C8/02; C23C14/00; C23C14/02; C23C14/021; C23C14/06; C23C14/14; C23C14/16; C23C14/58; C23C14/5806; C23C14/5846; C23C14/5853; Y; Y10; Y10S; Y10S428/00; Y10S428/922; Y10S428/923; Y10S428/924; Y10S428/926; Y10S428/9335; Y10S428/938; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/1266; Y10T428/12667; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847; Y10T428/12854; Y10T428/12861; Y10T428/12951; Y10T428/12972
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
21 words
The method of claim 1 in which said chromium layer is vacuum-deposited to a thickness of from 0.2 to 20 microinches.
Claim 2
Dependent Claim
21 words
The method of claim 1 in which said chromium layer is vacuum-deposited to a thickness of from 1 to 5 microinches.
Claim 3
Dependent Claim
18 words
The method of claim 1 in which said vacuum is less than about 1 X 10 4 torr.
Claim 4
Dependent Claim
23 words
The method of claim 1 in which said vacuum deposition of chromium is effected at a temperature of from 600* to 800* F.
Claim 5
Dependent Claim
22 words
The method of claim 1 in which said chromium coated steel is exposed to said oxidizing atmosphere immediately after the vacuum deposition.
Claim 6
Dependent Claim
85 words
The method of claim 1 further comprising the steps of cooling the chromium coated steel to temperatures below about 200* F. in said vacuum after the vacuum deposition of chromium, storing The cooled coated steel in air for periods no greater than about 1 week, reheating the coated steel in a vacuum of less than about 4 X 10 4 torr to a temperature of from 600* to 1,000* F., exposing the reheated coated steel to an oxidizing atmosphere, and then cooling the coated steel.
Claim 7
Dependent Claim
44 words
A steel having a corrosion-resistant protective coating consisting of a substantially oxygen free steel substrate having a high-purity vacuum-deposited chromium coating of at least 0.2 microinches in thickness, all pores, cracks and discontinuities in said chromium coating being plugged with a dense, nonporous magnetite.
Claim 8
Dependent Claim
19 words
The steel of claim 8 in which said chromium coating has a thickness of from 0.2 to 20 microinches.
Claim 9
Dependent Claim
19 words
The steel of claim 8 in which said chromium coating has a thickness of from 1 to 5 microinches.
References Cited (Backward Citations)
GB733912A
Cited
US3480483A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-10 | 1975-07-12 | 1976-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-10 | 1979-07-12 | 1980-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-10 | 1983-07-12 | 1984-01-11 | $7700.00 | Window Closed / Lapsed |