Kabushiki Kaisha Kobe Seiko Sho

Kan Momozaki

Takenori Nakayama

Shigeaki Miyauchi

Yasunobu Kawaguchi

Masataka Shimotsusa

Yoshinori Yamamoto

Norio Ohkouchi

Hideo Hata

Toyofumi Hasegawa

The present invention provides a steel wire rod or bar which exhibits good cold deformability even though it does not undergo spheroidizing annealing after hot rolling. The steel wire rod or bar with good cold deformability is characterized in that its ferrite structure contains no less than 25 nitride and carbide particles in a mixed state or composite state per 25 &mgr;m on average in a sectional area three-fourths of the diameter within the circumference of the rod or bar. Such nitride and carbide precipitates contribute to the reduction of flow stress at temperatures raised by heat generation at the time of cold deforming.

Steel wire rod or bar with good cold deformability and machine parts made thereof

Disclosed is a spring steel for a high corrosion resistant and high strength, which exhibits an excellent drawability without softening heat treatment after hot rolling, and which has a strength of 1900 MPa or more by quenching and tempering and an excellent corrosion resistance. The spring steel contains elements of C, Si, Mn and Cr, and elements of Ni and/or Mo in suitable amounts, the balance being essentially Fe and inevitable impurities, wherein the elements satisfy the following requirement:

Spring steel of high strength and high corrosion resistance

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Kobe, Japan

Kan Momozaki