Shinko Kosen Kogyo Kabushiki Kaisha

Masao Yamada

Nobuhiko Ibaraki

Masato Kaiso

Yukio Yamaoka

Hirofumi Ueki

Keiji Hattori

Masaru Kodama

Toshiki Suwa

A high strength steel strand for PC of a wire material having a pearlite structure and containing 0.80 to 1.30% of C, 0.60 to 2.50% of Si and 0.30 to 1.50% of Mn, remainder being Fe and unavoidable impurities, wherein a cementite portion of the wire material comprises a mixed structure of fibrous cementite and granular cementite, the volumetric proportion of the granular cementite to the total cementite is 10 to 40%, the particle diameter of the granular cementite is 40 to 300.ANG., and the strand has a tensile strength of 235 kgf/mm.sup.2 or higher and an elongation of 3.5% or greater.

High strength steel strand for prestressed concrete and method for

A steel material for colored springs is formed with a metallic deposit on the surface. The metallic deposit contains copper, zinc, and chromium. In an annealing process, copper and zinc diffuse in the deposit to exhibit a gold color tone while chromium is oxidized to exhibit a dark gray color tone. The combination of these color tones exhibits a beautiful black color tone which is distinguishable from a normal spring. The deposit improves the formability in the spring shaping process.

Steel material for a colored spring

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Takaishi, Japan

Masao Yamada