Nippon Kokan Kabushiki Kaisha

Riichi Shiono

Hidehisa Yamagishi

Mizuo Tanaka

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.

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Yokohama, Japan

Riichi Shiono