Nippon Kokan Kabushiki Kaisha

Kozi Iwase

Kazuhide Nakaoka

Kenzi Araki

Haruo Kubotera

Akihiko Nishimoto

Takao Kurihara

Nobuo Tanaka

In a continuous annealing process for a cold reduced steel strip substantially including a rapid cooling stage and a carbon precipitation treating stage into said process, the rapid cooling rate which is obtained by initial heating to above the recrystallization temperature and then slowly cooled for about 100 seconds to be above 200.degree. C./sec; and the starting temperature is controlled to be between 500.degree. C. and lower than 600.degree. C., thereby to obtain good press-formability of the continuously annealed steel strip.

Continuous annealing method for cold reduced steel strip

When an Al-killed steel consisting of, specially, 0.005% .ltoreq. [N] .ltoreq. 0.007%; 10 .times. [N] .ltoreq. Sol.Al. .ltoreq. 0.12%; and the ratio Sol.Al.%/[N]% controlled within the range of 10 to 20, is continuously cast, hot rolled, coiled at a high temperature, cold reduced and finally continuously annealed under special requirements, the steel strip is not at all inferior to the commercial base strip in mechanical properties and is made under high productivity and exhibits excellent uniformity in qualities.

Method of making cold-reduced Al-killed steel strip for press-forming by

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Machida, Japan

Kozi Iwase