Surface and Corrosion Characteristics of Tin-Free Steel—Chromium Type for Beverage Containers

Abstract

The new tin‐free steel‐chromium type (TFS‐CT) materials are described which constitute a new generation of tin‐free materials for can making. The steel is electroplated with a very thin film of metallic chromium approximately in. thick which is covered by a thin layer of chromium oxide. Processes for producing TFS‐CT are reviewed and the relative amounts of metallic chromium and chromium oxide are indicated for the products now available commercially. Performance requirements, bench tests for rapid evaluation of performance, and analytical techniques for measuring the amounts of chromium in the metallic and oxide layers are described. Results of electrochemical, and corrosion tests are reported which indicate the relative importance of the metallic chromium and chromium oxide layers as they affect corrosion resistance.