Method for manufacturing hot stamped body having vertical wall and hot stamped body having vertical wall

A method for manufacturing a hot stamped body, the method comprising:

• hot-rolling a slab containing chemical components which include, by mass %, 0.18% to 0.35% of C, 1.0% to 3.0% of Mn, 0.01% to 1.0% of Si, 0.001% to 0.02% of P, 0.0005% to 0.01% of S, 0.001% to 0.01% of N, 0.01% to 1.0% of Al, 0.005% to 0.2% of Ti, 0.0002% to 0.005% of B, and 0.002% to 2.0% of Cr, and the balance of Fe and inevitable impurities, to obtain a hot-rolled steel sheet;
• coiling the hot-rolled steel sheet which is subjected to hot-rolling;
• cold-rolling the coiled hot-rolled steel sheet to obtain a cold-rolled steel sheet;
• continuously annealing the cold-rolled steel sheet which is subjected to cold-rolling to obtain a steel sheet for hot stamping;
• and
• performing hot stamping by heating the steel sheet for hot stamping which is continuously annealed so that a highest heating temperature is equal to or higher than Ac3° C., and forming a vertical wall,
• wherein, in the hot-rolling, in finish-hot-rolling configured with a machine with 5 or more consecutive rolling stands, rolling is performed by setting a finish-hot-rolling temperature FiT in a final rolling mill Fi in a temperature range of (Ac3−80)° C. to (Ac3+40)° C., by setting time from start of rolling in a rolling mill Fi-3 which is a previous machine to the final rolling mill Fi to end of rolling in the final rolling mill Fi to be equal to or longer than 2.5 seconds, and by setting a hot-rolling temperature Fi-3T in the rolling mill Fi-3 to be equal to or lower than FiT+100° C., and after holding in a temperature range of 600° C. to Ar3° C. for 3 seconds to 40 seconds, coiling is performed,
• the continuous annealing includes:
• heating the cold-rolled steel sheet to a temperature range of equal to or higher than (Ac1−40)° C. and lower than Ac3° C.;
• cooling the heated cold-rolled steel sheet from the highest heating temperature to 660° C. at a cooling rate of equal to or less than 10° C./s;
• and
• holding the cooled cold-rolled steel sheet in a temperature range of 450° C. to 660° C. for 20 seconds to 10 minutes.