Sumitomo Metal Mining Company, Ltd.

Nippon Telegraph and Telephone Public Corporation

Nippon Telecommunication Engineering Company

Mitsushi Ishida

Toshio Takahashi

Kishio Arita

Akio Miyoshi

Hajime Izumimori

A copper alloy which is high in strength and electroconductivity is manufactured by casting, without chill casting, a copper alloy mass substantially consisting of copper and containing 0.2 to 1.5% by weight of chromium and 0.01 to 0.5% by weight of tin, hot working the cast copper alloy mass, then cooling, not slowly, the hot worked alloy mass without being subjected to any solid solution treatment, further cold working the cooled alloy mass, and thereafter subjecting the cold worked alloy mass to an aging treatment.

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Tokyo, Japan

Mitsushi Ishida