Shinko Kosen Kogyo Kabushiki Kaisha

Masaru Kodama

Yukio Yamaoka

Nobuhiko Ibaraki

Masato Kaiso

Hirofumi Ueki

Keiji Hattori

Masao Yamada

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

Facilitating the distinction among different spring steel products and at the same time improving their surface appearance and corrosion resistance by plating the surface of said different spring steel products before spring-forming with either alternate layers of Cu and Zn or alternate layers of Ni, Cu and Zn, the amount of Cu and Zn differing for steel products differing in size and/or material, to obtain color-developable spring steel products, drawing and taken coil spring-forming the resulting plated spring steel products, and low temperature annealing said resulting plated spring steel products to develop their colors, the colors being different for spring steel products differing in size and/or material, whereby mixing and erroneous assembly of spring steel products differing in size and/or material is prevented.

Method for facilitating distinction between different steel products

Growing community of inventors

Amagasaki, Japan

Masaru Kodama