Abstract: A copolyester film was laminated onto a steel sheet, this sheet having double layers consisting of a lower layer of metallic chromium and an upper layer of hydrated chromium oxide on a tin plated steel sheet in which 5 to 40% of the surface of the steel sheet is covered with plated tin and the remainder of the steel surface is exposed and the space between plated tin particles is 0.5 to 50 .mu.m, and a method for production of this copolyester resin film laminated steel sheet which comprises: (a) electroplating with tin under restricted conditions, (b) formation of said double layer on the plated tin and exposed steel surface and (c) lamination of the copolyester resin film at a temperature above the melting temperature of tin.

Abstract: A copolyester film was laminated onto a steel sheet, this sheet having double layers consisting of a lower layer of metallic chromium and an upper layer of hydrated chromium oxide on a tin plated steel sheet in which 5 to 40% of the surface of the steel sheet is covered with plated tin and exposed steel surface and a space between plated tin particles is 0.5 to 50 .mu.m, and a method for production of this copolyester resin film laminated steel sheet which comprises: (a) electroplating with tin under restricted conditions, (b) formation of said double layer on plated tin and exposed steel surface and (c) lamination of the copolyester resin film at above the melting temperature of tin.This copolyester resin film laminated steel sheet is suitable for applications wherein excellent corrosion resistance after severe forming is required, such as deeply drawn cans, drawn and redrawn cans, drawn and stretch formed cans, drawn and partially ironed cans and can ends in which a tab for easy opening is attached.

Abstract: Surface treated steel sheet having three layers consisting of a bottom layer of metallic chromium, a middle layer of metallic tin or tin-nickel alloy and a top layer of hydrated chromium oxide on a steel base, and a method for the continuous production of this surface treated steel sheet which comprises; (1) chromium plating on a steel base to form a layer of metallic chromium and hydrated chromium oxide, (2) tin plating by using a tin plating electrolyte having a low concentration of stannous ion or tin-nickel alloy plating by using a known tin-nickel alloy plating electrolyte, said electrolytes have a low current efficiency for tin or tin-nickel alloy plating, thereby removing said layer of hydrated chromium oxide from said chromium plated steel base; and (3) forming a layer of hydrated chromium oxide by a chromate treatment by using an acidic electrolyte containing hexavalent chromium ion.

Abstract: A method for producing a thin tin and nickel plated steel sheet having a surface structure in which the distribution of numerous nodules of metallic tin are observed by using an electron microscope on an iron-tin-nickel alloy layer formed on a steel sheet which comprises electroplating nickel on the steel sheet which is anodically treated in an alkaline electrolyte with a pH of above 10 followed by electrotinplating the nickel plated steel sheet, reflowing, quenching, and then chromate treating the tin and nickel plated steel sheet.This tin and nickel plated steel sheet is suitable for welded can materials since it is excellent in corrosion resistance after lacquering and weldability.

Abstract: Surface treated steel sheet having three layers consisting of a bottom layer of metallic chromium, a middle layer of metallic tin or tin-nickel alloy and a top layer of hydrated chromium oxide on a steel base, and a method for the continuous production of this surface treated steel sheet which comprises; (1) chromium plating on a steel base to form a layer of metallic chromium and hydrated chromium oxide, (2) tin plating by using a tin plating electrolyte having a low concentration of stannous ion or tin-nickel alloy plating by using a known tin-nickel alloy plating electrolyte, said electrolytes have a low current efficiency for tin or tin-nickel alloy plating, thereby removing said layer of hydrated chromium oxide from said chromium plated steel base; and (3) forming a layer of hydrated chromium oxide by a chromate treatment by using an acidic electrolyte containing hexavalent chromium ion.

Abstract: Tin free steel having three layers consisting of a bottom layer of metallic chromium, a middle layer of metallic nickel and a top layer of hydrated chromium oxide on a steel base, and a method for the continuous production of this tin free steel which comprises; (a) chromium plating a steel base to form a layer of metallic chromium and hydrated chromium oxide; (b) nickel plating the chromium plated steel base by using a nickel plating electrolyte sufficiently acidic to dissolve the hydrated chromium oxide and (c) forming a hydrated chromium oxide layer on the chromium plated nickel plated steel base.Instead of step (b) in the above method, a cathodic treatment in an acidic solution can be carried out for the removal of the hydrated chromium oxide formed during chromium plating, and thereafter nickel plating can be carried out.This tin free steel is useful for producing welded can bodies at high speed without removing the plated layer in the welded part, since it has an excellent weldability.

Abstract: Tin free steel having three layers consisting of a bottom layer of metallic chromium, a middle layer of nickel-zinc alloy containing 10 to 90 weight percent of zinc and a top layer of hydrated chromium oxide on a steel base, and a method for the continuous production of this tin free steel which comprises:(a) chromium plating a steel base to form a layer of metallic chromium and hydrated chromium oxide, (b) nickel-zinc alloy plating the chromium plated steel base by using a nickel-zinc alloy plating electrolyte sufficiently acidic to dissolve the hydrated chromium oxide and (c) forming a hydrated chromium oxide layer on the chromium plated nickel-zinc plated steel base.Instead of (b) in the above method, a cathodic treatment in an acidic solution can be carried out for the removal of hydrated chromium oxide formed during chromium plating, and thereafter nickel-zinc alloy plating can be carried out by using a known nickel-zinc alloy plating electrolyte.

Abstract: A method of treating steel sheets which have good corrosion resistance after forming, which comprises coating a steel sheet with a solution which contains:(a) water-soluble or water-dispersible lithium silicate at a concentration of 2 to 250 g/l, which lithium silicate is a mixture of silicic acid or silicate and lithium salt in a molar ratio of 20:1 to 1:1.(b) at least one water-soluble or water-dispersible saturated or unsaturated fatty acid compound, higher alcohol wax, polyethylene type resin, fluorine type resin or silicone type resin at a concentration of 1 to 250 g/l.