Hot stamped component and method for manufacturing same

Abstract

According to an aspect of the present disclosure, provided is a method of manufacturing a hot stamping component in which a residual stress analysis value satisfies a preset condition. The method includes heating a blank; forming a molded body by hot stamping the blank; and cooling the molded body to form a hot stamped component. The residual stress analysis value may be a product of a magnitude of an X-ray diffraction analysis (XRD) value obtained by quantifying residual stress by XRD analysis and a magnitude of an electron backscatter diffraction (EBSD) value obtained by quantifying an orientation by EBSD analysis, and the preset condition is about 2.85* 10-4 Degree*MPa/µm2 or greater and about 0.05 Degree*MPa/µm2 or less.

1 . A method of manufacturing a hot stamping component in which a residual stress analysis value satisfies a preset condition, the method comprising:
 heating a blank;   forming a molded body by hot stamping the blank; and   cooling the molded body to form a hot stamped component, 
 wherein the residual stress analysis value is a product of a magnitude of an X-ray diffraction analysis (XRD) value obtained by quantifying residual stress by XRD analysis and a magnitude of an electron backscatter diffraction (EBSD) value obtained by quantifying an orientation by EBSD analysis, and
 the preset condition is about 2.85*10 -4  Degree*MPa/µm 2  or greater and about 0.05 Degree*MPa/µm 2  or less. 
 
     
     
         2 . The method of  claim 1 , wherein the heating of the blank comprises:
 step-heating the blank while passing a plurality of sections in a heating furnace wherein a temperature range increases gradually in the plurality of sections provided; and   soaking the blank to a temperature of about Ac3 or higher.   
     
     
         3 . The method of  claim 2 , wherein, in the plurality of sections, a ratio of a length of sections for step-heating the blank to a length of a section for soaking the blank is about 1:1 to 4:1. 
     
     
         4 . The method of  claim 2 , wherein the temperature in the plurality of sections increases in a direction from an inlet of the heating furnace to an outlet of the heating furnace. 
     
     
         5 . The method of  claim 4 , wherein, in the step-heating, the temperature increase rate of the blank is in a range from about 6° C./s to about 12° C./s. 
     
     
         6 . The method of  claim 5 , wherein, in the plurality of sections, a temperature of a section for soaking the blank is higher than a temperature of sections for step-heating the blank. 
     
     
         7 . The method of  claim 2 , wherein the blank is present in the heating furnace for a range from about 180 seconds to about 360 seconds. 
     
     
         8 . The method of  claim 1 , wherein the cooling of the molded body to form a hot stamping component comprises maintaining the molded body for about 3 seconds to about 20 seconds in a press mold at a temperature below a temperature at which martensitic transformation starts. 
     
     
         9 . The method of  claim 8 , wherein the molded body is cooled in the press mold at an average cooling rate of 15° C./s or greater to a temperature at which martensitic transformation is terminated. 
     
     
         10 . The method of  claim 1 , wherein the hot stamping component comprises:
 a martensite phase having an area fraction of 80% or greater; and   an iron-based carbide located inside the martensite phase and having an area fraction of less than 5% based on the martensite phase.   
     
     
         11 . The method of  claim 10 , wherein 
 the iron-based carbide has an acicular form, and   the acicular form has a diameter of less than 0.2 µm and a length of less than 10 µm.   
     
     
         12 . The method of  claim 10 , wherein:
 the martensite phase comprises a lath phase,   the iron-based carbide comprises a first iron-based carbide horizontal to a longitudinal direction of the lath and a second iron-based carbide perpendicular to the longitudinal direction of the lath, and   an iron-based carbide reference area fraction of the first iron-based carbide is greater than an iron-based carbide reference area fraction of the second iron-based carbide.   
     
     
         13 . The method of  claim 12 , wherein the first iron-based carbide has an angle with the longitudinal direction of the lath of 0° or greater and 20° or less and the iron-based carbide reference area fraction of 50% or greater. 
     
     
         14 . The method of  claim 12 , wherein the second iron-based carbide has an angle with the longitudinal direction of the lath of 70° or greater and 90° or less and the iron-based carbide reference area fraction of less than 50%. 
     
     
         15 . A hot stamping component in which a residual stress analysis value satisfies a preset condition,
 wherein the residual stress analysis value is a product of a magnitude of an X-ray diffraction analysis (XRD) value obtained by quantifying residual stress by XRD analysis and a magnitude of an electron backscatter diffraction (EBSD) value obtained by quantifying an orientation by EBSD analysis, and   the preset condition is about 2.85*10 -4  Degree*MPa/µm 2  or greater and about 0.05 Degree*MPa/µm 2  or less.   
     
     
         16 . The hot stamping component of  claim 15 , wherein 
 the hot stamping component includes a martensite phase having an area fraction of 80% or greater, and   an iron-based carbide located inside the martensite phase and having an area fraction of less than 5% based on the martensite phase.   
     
     
         17 . The hot stamping component of  claim 16 , wherein 
 the iron-based carbide has an acicular form, and   the acicular form has a diameter of less than 0.2 µm and a length of less than 10 µm.   
     
     
         18 . The hot stamping component of  claim 16 , wherein
 the martensite phase comprises a lath phase,   the iron-based carbide comprises a first iron-based carbide horizontal to a longitudinal direction of the lath and a second iron-based carbide perpendicular to the longitudinal direction of the lath, and   an iron-based carbide reference area fraction of the first iron-based carbide is greater than an iron-based carbide reference area fraction of the second iron-based carbide.   
     
     
         19 . The hot stamping component of  claim 18 , wherein the first iron-based carbide has an angle with the longitudinal direction of the lath of 0° or greater and 20° or less and the iron-based carbide reference area fraction of 50% or greater. 
     
     
         20 . The hot stamping component of  claim 18 , wherein the second iron-based carbide has an angle with the longitudinal direction of the lath is 70° or greater and 90° or less and the iron-based carbide reference area fraction of less than 50%.