Kabushiki Kaisha Kobe Seiko Sho

Nhk Spring Co., Ltd.

Shinko Wire Company, Ltd.

Shinko Kosen Kogyo Kabushiki

Tadayoshi Fujiwara

Noritoshi Takamura

Nobuhiko Ibaraki

Sumie Suda

Tetsuo Jinbo

Yoshiro Yamada

Yukio Yamaoka

Yasunobu Kawaguchi

Hiroyuki Takahashi

Yasuhiro Oki

Naoki Terakado

Satoru Tendo

Atushi Inada

Satoru Tendoh

Takashi Taniguchi

Kazuichi Hamada

A steel wire has tempered martensite, comprises, as essential components, by mass, C: 0.53 to 0.68%; Si: 1.2 to 2.5%; Mn: 0.2 to 1.5%; Cr: 1.4 to 2.5%; Al: 0.05% or less; further comprises, as a selective component, Ni: 0.4% or less; V: 0.4% or less; Mo: 0.05 to 0.5%; or Nb: 0.05 to 0.5%; and further comprises remainder essentially consisting of Fe and inevitable impurities, wherein the grain size number of prior austenite is 11.0 or larger, and the proof stress ratio (&#x3c3;/&#x3c3;), namely, a ratio of 0.2% proof stress (&#x3c3;) to tensile strength (&#x3c3;) is 0.85 or lower. Satisfying the above requirements makes it possible to produce a steel wire for high-strength spring excellent both in workability (cold workability), and in sag resistance and fatigue properties.

Steel wire for high strength spring excellent in workability and high strength

Disclosed is a steel wire rod for hard-drawn springs capable of exhibiting fatigue strength and sag resistance equivalent to or higher than springs made of an oil-tempered wire. The steel wire rod contains carbon in a range from 0.5 to less than 0.7 mass %, silicon in a range from 1.4 to 2.5 mass %, manganese in a range from 0.5 to 1.5 mass %, chromium in a range from 0.05 to 2.0 mass %, and vanadium in a range from 0.05 to 0.40 mass %, and has an area ratio Rp with respect to pearlite which satisfies the mathematical expression (1):(area %)&#x2267;55&#xd7;[]+61&#x2003;&#x2003;(1)where [C] denotes the content (mass %) of carbon.

Steel wire rod for hard drawn spring, drawn wire rod for hard drawn spring and hard drawn spring, and method for producing hard drawn spring

Wire rods containing an adequate quantity of C within the range from 0.70 to 1.00%, Si from 0.5 to 3.0%, Mn from 0.30 to 2.0%, Cr from 0.10 to 0.5%, Al from 0.030 to 0.10% and N from 0.004 to 0.015% and unavoidable impurities, and with Fe for all the rest are subjected to re-heat patenting to increase the tensile strength to 135 kgf/mm.sup.2 or higher, then are drawn by adequately selecting the conditions, number of times of drawing in the range from 7 to 16 times, drawings speed from 50 to 550 m/minute, extent of drawing form 70-90, and water cooling immediately after each drawing to manufacture steel wires of high strength and high toughness. The wires are used as PC wires, steel wires for skewed bridge cables, steel stranded wires, spring wires, main cable wires for extra-long suspension bridge large diameter wires for core of aluminum cables steel reinforced (transmission cable), and as galvanized steel wires for such applications.

High strength and high toughness steel bar, rod and wire and the process

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Amagasaki, Japan

Tadayoshi Fujiwara