| 摘要 |
PROBLEM TO BE SOLVED: To provide a method useful for obtaining a press-molded product capable of achieving a balance between high strength and elongation at a high level, and a press-molded product exercising the characteristics.SOLUTION: A steel sheet for hot pressing having a predetermined chemical composition, having Ti containing deposits contained in the steel sheet with an average circle equivalent diameter of 3 nm or more of those with a circle equivalent diameter of 30 nm or less, and in which a deposit Ti amount and a whole Ti amount in steel satisfy a relationship of formula (1), is heated to a temperature of an Actransformation temperature or more, and 950°C or less. Then press forming is started, the steel sheet is cooled to a temperature 100°C or more less than a bainite transformation start temperature Bs and the same or more than a martensite transformation start temperature Ms while maintaining an average cooling speed of 20°C/s or more in a die during forming and after forming, and is cooled at an average cooling speed of 10°C/s or less from that temperature to 200°C or less. (1): deposit Ti amount (mass%)-3.4[N]≥0.5×{whole Ti amount (mass%)-3.4[N]}. In formula (1), [N] represents a content (mass%) of N in the steel. |
