| 摘要 |
PROBLEM TO BE SOLVED: To obtain: a carburization part having sufficient surface fatigue strength and a carburization part having surface fatigue strength and flex fatigue strength; and a steel material for obtaining the carburization parts.SOLUTION: The present invention is a steel material for vacuum carburization containing C, Si, Mn, S, P, Cr, Mo, V, Al, and N, in which an average circle-equivalent diameter of a vanadium carbide is 25 nm or less. The present invention also includes a method for manufacturing the steel material. Specifically, the method includes subjecting a steel having a predetermined chemical ingredient composition to blooming by holding the steel at 1200°C or above for 30-300 minutes, followed by hot rolling by setting a heating temperature before the hot rolling to 950°C or above and heating retention time to 30 minutes to 5 hours. |
