Method of producing tin-free steel sheets
US4519879A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 26, 1983 |
| Grant date | May 28, 1985 |
| Priority date | — |
| Expiry date | May 26, 2003 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC25D11/38
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Tin-free steel sheets having improved resistance to retorting treatment are produced by chromium plating a steel sheet through cathodic electrolysis in a chromium ion-containing aqueous solution to form a metallic chromium coating, reversely electrolyzing the chromium plated steel sheet by a successive anodizing treatment in the same solution, and subjecting the sheet to an electrolytic chromate treatment in another aqueous solution of chromic acid, a chromate or dichromate. The chromium plating and reverse electrolysis should be carried out so as to satisfy the equations: EQU x+1.ltoreq.y.ltoreq.x+4 EQU 1.ltoreq.x.ltoreq.6 where y and x are the quantities of hydrated chromium oxides present on one surface of the steel sheet after the chromium plating step and after the reverse electrolysis step, respectively, as expressed in mg (in terms of metallic chromium) per square meter of the surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.