Nippon Kokan Kabushiki Kaisha

Hidehisa Yamagishi

Mizuo Tanaka

Hiroshi Takano

Yoshitaka Kashiyama

Riichi Shiono

Atuhiko Murao

Hisao Tsutsumi

In order to brighten the surface of a tin-plated layer of steel strip tin-plated on a commonly known continuous electrolytic tin-plating line, said strip is heated in a traditional continuous heating furnace for rapid fusion of its tin-plated layer, and then promptly quenched for solidification. In doing so, said quenching is carried out in two stages aiming at obtaining an excellent corrosion resistance as well as preventing the occurrence of quench stains. In other words, a relatively low-rate quenching in the initial stage is carried out by spraying a quenching liquid mist or a stream of high-pressure quenching liquid onto both sides of said strip across the entire width, uniformly on the same horizontal level, in the air above the surface of quenching liquid in a quenching tank immediately following said heating furnace, before said strip comes into the quencing liquid in said quenching tank. Then, a relatively high-rate quenching in the second stage is carried out for said strip having come into the quenching liquid in said quenching tank by spraying quenching liquid of a high-pressure and in a large quantity onto both sides of said strip across the entire width, uniformly on the same horizontal level, beneath the surface of quenching liquid in said quenching tank.

Method for continuously quenching electrolytic tin-plated steel strip

Streams of quenching liquid are uniformly sprayed onto both surfaces of a continuously electrolytic tinplated steel strip, having a tin-plated layer fused by heating in a heating furnace, in moving substantially vertically downward, said streams of quenching liquid being sprayed on substantially the same horizontal level over the entire width of said strip in the air above the surface of quenching liquid in a quenching tank, thereby quenching said strip to solidify said fused tin-plated layer, said streams of quenching liquid being sprayed with the use of two spray nozzles under the following conditions:

A steel sheet coating having high corrosion-resistivity and paint-adhesivity can be obtained by applying a water solution of specific composition described hereinafter on a steel sheet, followed by drying; and exposing the coating to ultraviolet rays in an air atmosphere; said water solution contains a chemical compound which has been prepared by reacting a prepolymer of an epoxy resin with acrylic acid or methacrylic acid in order to introduce vinyl groups into the molecules of said prepolymer, another chemical compound of chromate or dichromate for chelation and a molybdenum compound as a stabilizer.

Method for forming corrosion-resistant coating on a steel sheet

Method of electrolytically post-treating an electrolytically chromate treated or metallic chromium plated steel sheet comprises anodically treating the said electrolytically chromate threated or metallic chromium plated steel sheet in an electrolyte other than an aqueous solution easily dissolving metallic chromium. The anodically treated steel sheet can be treated cathodically in an electrolyte with the said anodically treated steel sheet being employed as the cathode.

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Yokohama, Japan

Hidehisa Yamagishi