Toyo Kohan Co., Ltd.

Migita Patent Office

Kenji Hizuka

Tsuneo Inui

Yoshikazu Kondo

Hitoshi Kuroda

Fumio Kunishige

Kinji Saijo

Nobuyoshi Shimizu

Hideaki Hamano

Tin-free steel having a first layer of metallic chromium on a steel base and a second layer of hydrated chromium oxide on the first layer, in which the atomic ratio of sulfur and the atomic ratio of fluorine to the sum of chromium, oxygen, sulfur and fluorine in the second layer are respectively not greater than 2.5 atomic percent and not greater than 10 atomic percent. This tin-free steel can be used for a nylon-adhered can body to be subjected to a hot-packing or retort treatment, since it has excellent lacquer adhesion after aging in hot water and under retort conditions.

Tin-free steel can body

Process for producing tin-free steel

A method for the pretreatment of tin-free steel which comprises an anodic treatment or an anodic treatment after a cathodic treatment of an acid pickled steel sheet in an alkaline electrolyte with a pH of above 8, said steel sheet consisting of an upper layer of hydrated chromium oxide and a lower layer of metallic chromium. This pretreated tin-free steel has excellent lacquer adhesion after aging in hot water and under retort conditions.

Method for pretreatment in the production of tin-free steel

A method for the pretreatment of tin-free steel which comprises a cathodic treatment after an anodic treatment of a degreased steel sheet in an acid chromate electrolyte, said steel sheet consisting of an upper layer of hydrated chromium oxide and a lower layer of metallic chromium. This pretreated tin-free steel has excellent lacquer adhesion after aging in hot water and under retort conditions.

Growing community of inventors

Kudamatsu, Japan

Kenji Hizuka