Method of manufacturing a hot-stamped part
A method of manufacturing a hot-stamped part includes: inserting a blank into a heating furnace including a plurality of sections with different temperature ranges; step heating the blank in multiple stages; and soaking the blank at a temperature of about Ac3 to about 1,000° C., wherein in the step of heating the blank, a temperature condition in the heating furnace satisfies the following equation: 0<(Tg−Ti)/Lt<0.025° C./mm, where Tg denotes a soaking temperature (° C.), Ti denotes an initial temperature (° C.) of the heating furnace, and Lt denotes a length (mm) of step heating sections.
1. A method of manufacturing a part to be hot-stamped, the method comprising:
inserting a blank into a heating furnace, wherein the heating furnace includes heating sections and soaking sections;
step heating the blank as the blank passes through the heating sections;
soaking the blank at a temperature of Ac3 to 1,000° C. as the blank passes through the soaking sections;
transferring the soaked blank from the heating furnace to a press mold;
forming a molded body by hot-stamping the transferred blank; and
cooling the formed molded body, wherein, in the step heating of the blank, a temperature condition in the heating furnace satisfies formula:
0<(Tg—Ti)/Lt<0.025° C./mm
wherein Tg denotes a soaking temperature (° C.), Ti denotes an initial temperature (° C.) of the heating furnace, and Lt denotes a total length (mm) of the heating sections,
wherein the soaking is performed in the soaking sections having same temperature range in the heating furnace,
wherein the blank includes a tailor rolled blank (TRB) having partially different thicknesses obtained by rolling a plate material having a uniform thickness.
2. The method of claim 1 , wherein among the plurality of sections, a ratio of a total length of the heating sections to a total length of the soaking sections is 1:1 to 4:1.
3. The method of claim 2 , wherein among the plurality of sections, a temperature of a section for soaking the blank is greater than a temperature of other sections for the step heating of the blank.
4. The method of claim 1 , wherein in the cooling of the formed molded body, the blank is held in the press mold for about 3 seconds to about 20 seconds.
5. The method of claim 1 , wherein the blank and an additional blank have different thicknesses and are simultaneously transferred into the heating furnace.
6. The method of claim 1 , wherein a difference in temperature between two adjacent sections among the plurality of sections for step heating the blank is greater than 0° C. and less than or equal to 100° C.
7. The method of claim 1 , wherein the blank remains in the heating furnace for 180 seconds to 360 seconds.
8. The method of claim 1 , wherein in the transferring of the soaked blank from the heating furnace to the press mold, the soaked blank is air-cooled for 10 seconds to 15 seconds.