Sumitomo Metal Industries, Inc.

Toshihiko Kawai

Hajime Nashiwa

Tsutomu Nagahata

Muneyoshi Takeyama

Youzi Yamaguchi

Tsuneaki Kobayashi

Steel plate having an excellent resistance to hydrogen induced cracking is obtained from a continuously cast slab having the following composition, C 0.01-0.30% by weight, Si 0.05-0.60% by weight, Mn 0.40-2.50% by weight, Sol Al 0.005-1.00% by weight, S 0.003% and lower by weight, the weight ratio of Ca/S is 2-10, the remainder being substantially Fe, through the steps of hot primary reduction rolling the cast slab, heating it at the temperature of 1200.degree. C. or higher for 10 hours or longer, and ordinary rolling it.

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Wakayama, Japan

Toshihiko Kawai