| 摘要 |
A method of the present invention includes the steps of heating a steel sheet for hot pressing use to a temperature of Ac 3 transformation point or above and 950°C or below, the steel sheet for hot pressing use containing a predetermined chemical component composition, some of Ti-containing precipitates contained in the steel sheet, each of which having an equivalent circle diameter of 30 nm or less, having an average equivalent circle diameter of 3 nm or more, and the precipitated Ti amount and the total Ti amount in the steel fulfilling the relationship represented by formula (1) shown below, thereafter starting press forming, and being held at the bottom dead point and being cooled to a temperature lower than martensite transformation starting temperature Ms while securing the average cooling rate of 20°C/s or more within a tool. Precipitated Ti amount mass % - 3.4 N ‰¥ 0.5 × total Ti amount mass % - 3.4 N
(In the formula (1), [N] represents the content (mass%) of N in the steel.) |
