| 摘要 |
The purpose of the present invention is to provide a rolled steel material which is for use in a high-strength spring, which exhibits excellent wire drawability even when the amount of an alloying element added is reduced, and which exhibits excellent corrosion fatigue characteristics after quenching and tempering. A rolled steel material for a high-strength spring, characterized in that: the rolled steel contains C, Si, Mn, P, S, Al, Cu and Ni; the nondiffusible hydrogen content is 0.40massppm or less; the area fraction of ferrite in terms of percentage satisfies relationship (1); and the total area fraction of bainite and martensite is 2% or less. Area fraction of ferrite < {(0.77 - [C])/0.77 - [C]/3 + 0.08} × 100 ... (1) [wherein "[element]" represents the content of the element in terms of mass%]. |
