Toyo Seikan Kaisha, Ltd.

Chikara Yurita

Yoichi Kitamura

Hisashi Hotta

Makoto Ito

Disclosed is a process for the preparation of welded cans, which comprises forming a blank comprised of a surface-treated steel plate into a cylinder and passing a lap portion of the formed cylinder between a pair of electrode rollers through an electrode wire to effect electric resistance welding, wherein said surface-treated steel plate comprises a layer of metallic tin or a tin-iron alloy formed on the steel plate substrate in an amount of 0.05 to 1.0 g/m.sup.2 as calculated as metallic tin and a hydrated chromium oxide layer formed on said tin layer in an amount of 0.005 to 0.05 g/m.sup.2 as calculated as metallic chromium and electric resistance welding is carried out in an inert atmosphere in the state where an electrode wire having a plating layer of tin or a tin alloy having a thickness of 0.1 to 20 .mu.m is kept in close contact with the surface of said surface-treated steel plate. In the inner and outer surface portions of the side seam of a welded can prepared according to this process, the thickness of the oxide layer is controlled below 400 .ANG. and the amount of tin in these inner and outer surface portions is at least 60% of the amount of tin in the starting surface-treated steel plate, and this welded can is excellent in the corrosion resistance, lacquer adhesion and appearance characteristics of the seam.

Welded can and process for preparation thereof

Disclosed is a process for the preparation of welded cans, which comprises forming a blank comprised of a surface-treated steel plate into a cylinder and passing a lap portion of the formed cylinder between a pair of electrode rollers through an electrode wire to effect electric resistance welding, wherein said surface-treated steel plate comprises a layer of metallic tin or a tin-iron alloy formed on the steel plate substrate in an amount of 0.05 to 1.0 g/m.sup.2 as calculated as metallic tin and a hydrated chromium oxide layer formed on said tin layer in an amount of 0.005 to 0.05 g/m.sup.2 as calculated as metallic chromium and electric resistance welding is carried out in an inert atmosphere in the state where an electrode wire having a plating layer of tin or a tin alloy having a thickness of 0.1 to 20 .mu.m is kept in close contact with the surface of said surface-treated steel plate. In the inner and outer surface portions of the side seam of a welded can prepared according to this process, the thickness of the oxide layer is controlled below 400 A and the amount of tin in these inner and outer surface portions is at least 60% of the amount of tin in the starting surface-treated steel plate, and this welded can is excellent in the corrosion resistance, lacquer adhesion and appearance characteristics of the seam.

A method of manufacturing a welded can body from tinplate or a tin-iron alloy plated steel sheet comprises overlapping the opposite marginal portions of a blank of the tinplate or the tin-iron plated steel sheet to form a can body preform having an overlapping portion, applying at least to the cut edges of the marginal portions of the blank a fluxing agent promoting wetting of steel with molten tin, and electrical resistance seam welding the overlapping portion in a nonoxidizing atmosphere by employing a pair of wire electrodes each covered by a layer of metallic tin on the surface thereof facing the overlapping portion. The welded portion has improved corrosion resistance, as an extruded weld portion and a remaining cut edge surface portion thereof are covered with tin transferred from the surfaces of the wire electrodes and/or the tinplate during the welding operation.

Method of manufacturing a welded can body

Disclosed is a process for the preparation of welded cans, which comprises forming a blank into a cylinder and passing a lap portion of the formed cylinder between a pair of electrode rollers through an electrode wire to effect electric resistance welding, wherein said blank is a tin-free steel blank comprising a steel plate substrate, a layer of metallic chromium formed on the surface of the steel plate substrate and a layer of chromium oxide formed on the metallic chromium layer, and electric resistance welding is carried out in an inert atmosphere in the state where an electrode wire having a plated layer of a soft metal selected from the group consisting of tin and alloys thereof, the thickness of said plated layer being 0.1 to 20 .mu.m, is kept in close contact with the chromium oxide layer of the tin-free steel blank. The inner and outer surfaces of the side seam of a welded can according to this process are covered with a continuous or discontinuous protecting covered layer including a metallic chromium layer and a chromium oxide layer formed thereon, and the thickness of steel oxide exposed through this discontinuous portion is controlled below 400 A. Since exposure of steel in the inner and outer surfaces of the seam is thus controlled, the corrosion resistance, lacquer adhesion and appearance charcteristics of the seam are highly improved in this welded can.

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Kawasaki, Japan

Chikara Yurita