US4421828A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Steel sheet carrying a protective layer and process for producing such a sheet
Assignee: Carnaud SA
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Filing: 1980-09-08
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Granted: 1983-12-20
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Expires: 2000-09-08
Abstract
Abstract The invention relates to mild steel sheet, having deposited on at least one of its major faces a sub-layer of tin in an amount of 0.1 to 1.05 g/l and a composite coating containing chronmium and chronmium oxide. The content of chromium in the composite coating is more than 5 μg/cm 2 while the content of chromium oxide in the coating, expressed in terms of chromium, is less than 2.5 μg/cm 2 . The resultant sheets give improved welds when joined by electric welding and are particularly suited for making can bodies for food cans.
Inventors
- 👤 Raymond Allouf
- 👤 Claude Mergey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:29
CPC Classifications
C; C25; C25D; C25D11/00; C25D11/38; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12583; Y10T428/1259; Y10T428/1266; Y10T428/12708; Y10T428/12722; Y10T428/12771; Y10T428/12806; Y10T428/12826; Y10T428/12847
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
169 words
A process for the production from mild steel sheets of a steel sheet carrying a protective layer suitable for the manufacture of metal containers, in particular food cans, the protected steel sheet possessing an electrical contact resistance which is lower than 100×10 -5 ohms, so as to permit roller spot welding during the manufacture of said containers, which process includes the steps of: (a) depositing on the surface of the metal sheet a layer of tin in an amount of from 0.1 to 1.05 g/m 2 of the surface area of the metal sheet to form a layer of tin which is unalloyed to the steel, and then (b) electrolytically depositing a layer of chromium metal and chromium oxide on said unalloyed tin layer the said layer being deposited so that the said layer contains at least 5 micrograms per square centimeter of the surface area of the metal sheet (5 μg/cm 2 ) of metallic chromium and from 0.6 to 2.5 μg/cm 2 of chromium in oxidized form.
Claim 2
Dependent Claim
169 words
A process for the production from mild steel sheets of a steel sheet carrying a protective layer suitable for the manufacture of metal containers, in particular food cans, the protected steel sheet possessing an electrical contact resistance which is lower than 100×10 -5 ohms, so as to permit roller spot welding during the manufacture of said containers, which process includes the steps of: (a) depositing on the surface of the metal sheet a layer of tin in an amount of from 0.1 to 1.05 g/m 2 of the surface area of the metal sheet to form a layer of tin which is unalloyed to the steel, and then (b) electrolytically depositing a layer of chromium metal and chromium oxide on said unalloyed tin layer the said layer being deposited so that the said layer contains at least 5 micrograms per square centimeter of the surface area of the metal sheet (5 μg/cm 2 ) of metallic chromium and from 0.6 to 2.5 μg/cm 2 of chromium in oxidized form.
Claim 3
Dependent Claim
24 words
A process according to claim 1, wherein the layer of chromium metal and chromium oxide contains at most 10 μg/cm 2 of chromium metal.
Claim 4
Dependent Claim
64 words
A process according to claim 1, in which the layer of chromium metal and chromium oxide is deposited by a process which comprises passing the tin-coated metal sheet, which acts as the cathode, through an electrolysis bath containing a solution of chromium trioxide, and after the composite layer has been deposited, reducing the content of chromium oxide in this layer to a specified range.
Claim 5
Dependent Claim
75 words
A process according to any one of claims 1, 2 or 3, wherein the layer of chromium metal and chromium oxide is deposited by a process which comprises passing the tin-coated metal sheet, which acts as the cathode, through at least one electrolysis bath containing a solution of chromium trioxide, and wherein in at least a first electrolysis bath, the content of Cr 3+ ions is kept at a value of at most 0.5 g/liter.
Claim 6
Dependent Claim
25 words
A process according to claim 4, wherein the specified content of Cr 3+ ions is maintained by passing the bath over a cation exchange resin.
Claim 7
Dependent Claim
24 words
A process according to claim 4, wherein the total content of chromium in the bath, calculated as chromium, is from 25 to 50 g/liter.
Claim 8
Dependent Claim
25 words
A process according to claim 4, wherein the tin-coated metal sheet is made cathodic relative to an anode, before entering at least the first bath.
Claim 9
Dependent Claim
136 words
A steel sheet carrying a protective layer and being suitable for the manufacture of metal containers, in particular food cans, the protected steel sheet having an electrical contact resistance which is lower than 100×10 -5 ohms, so as to permit roller spot welding during the manufacture of the containers, the steel sheet comprising a sheet of mild steel having a layer of tin deposited on the surface of the sheet, in an amount of from 1.0 to 1.05 g/m 2 , the tin layer not being alloyed with the steel, and a layer of metallic chromium and chromium oxide deposited on the resultant tin-coated metal sheet, the said layer containing at least 5 micrograms per square centimeter of metallic chromium (5 μg/cm 2 ) and from 0.6 to 2.5 μg/cm 2 of chromium in oxidized form.
Claim 10
Dependent Claim
136 words
A steel sheet carrying a protective layer and being suitable for the manufacture of metal containers, in particular food cans, the protected steel sheet having an electrical contact resistance which is lower than 100×10 -5 ohms, so as to permit roller spot welding during the manufacture of the containers, the steel sheet comprising a sheet of mild steel having a layer of tin deposited on the surface of the sheet, in an amount of from 1.0 to 1.05 g/m 2 , the tin layer not being alloyed with the steel, and a layer of metallic chromium and chromium oxide deposited on the resultant tin-coated metal sheet, the said layer containing at least 5 micrograms per square centimeter of metallic chromium (5 μg/cm 2 ) and from 0.6 to 2.5 μg/cm 2 of chromium in oxidized form.
Claim 11
Dependent Claim
25 words
A steel sheet according to claim 8, wherein the layer of chromium metal and chromium oxide contains at most 10 μg/cm 2 of metallic chromium.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-12-19 | 1987-06-20 | 1987-12-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-12-19 | 1991-06-20 | 1991-12-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-12-19 | 1995-06-20 | 1995-12-20 | $7700.00 | Window Closed / Lapsed |