Tin-free steel strips useful in the manufacture of welded cans and process for making
US4687713A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 14, 1986 |
| Grant date | Aug 18, 1987 |
| Priority date | — |
| Expiry date | Mar 14, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/12993
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A tin-free steel strip comprising a steel strip, 40 to 150 mg/m.sup.2 of a metallic chromium layer on the steel surface, and 5 to 25 mg/m.sup.2 of a chromium compound containing layer thereon wherein the metallic chromium layer contains a plurality of protrusions, exhibits improved corrosion resistance and weldability and is thus useful in the manufacture of welded cans. Preferably, 1.times.10.sup.11 to 1.times.10.sup.14 protrusions having a diameter of 5 to 1000 nm at the base thereof are present per square meter of the metallic chromium layer surface. The tin-free steel strip is produced by chromium plating a steel strip in an aqueous solution containing CR.sup.6+ preferably to a weight of 40 to 140 mg/m.sup.2, subjecting the chromium plated strip to anodic electrolysis, preferably at an eectricity quantity of 0.1 to 10 C/dm.sup.2, and subjecting the strip to a cathodic treatment in an aqueous solution containing Cr.sup.6+ and a chromium plating aid so as to deposit additional metallic chromium, preferably in a weight of 10 to 60 mg/m.sup.2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.