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AssigneeKabushiki Kaisha Kobe Seiko Sho
InventorsShigenobu Nanba, Hiroshi Yaguchi, Masataka Shimotsusa, Nobuhiko Ibaraki, Takenori Nakayama, Takashi Iwata, Yoshinori Yamamoto, Norio Ohkouchi, Mamoru Nagao
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The present invention provides a spring steel with excellent performance, characterized in that the spring steel is produced by making a spring steel contain an appropriate amount of at least one or more of Ti, Nb, Zr, Ta, and Hf, thereby generating fine inclusions including carbide, nitride, sulfides and/or their complex compounds, to make the inclusions exert the effect of trapping diffusive hydrogen whereby the resistance to hydrogen embrittlement is enhanced, wherein the size and number of the coarse inclusions are regulated, thereby suppressing the decrease of the fatigue life. The spring steel can provide a valve spring or a suspension spring or the like, with enhanced strength and higher stress resistance, together with improved resistance to hydrogen embrittlement and fatigue.
A spring steel, comprising at least one element selected from the group consisting of Ti at 0.001 to 0.5% (the term "%" herein means "mass %", the same is true hereinbelow), Nb at 0.001 to 0.5%, Zr at 0.001 to 0.5%, Ta at 0.001 to 0.5% and Hf at 0.001 to 0.5%, and also comprising C at 0.3% to 0.55%, Si at 1.49 to 2.50%, Mn at 0.005 to 2.0%, N of 1 to 200 ppm and S of 5 to 300 ppm, with a balance beginning essentially Fe and inevitable impurities,
Dependencies are inferred from the claim text.