Abstract: Disclosed is a hot stamped part, which has improved toughness while maintaining high strength and high hardness, and a method for manufacturing the same. The hot stamped part is formed by performing hot stamping using an iron-based alloy, and includes a reinforced portion formed to have a martensite structure, a softened portion formed to have ferrite and bainite structures, and a transition portion formed between the reinforced portion and the softened portion. The reinforced portion, the transition portion and the softened portion are formed in the thickness direction of the hot stamped part.

Abstract: Disclosed is a hot stamped part, which has improved toughness while maintaining high strength and high hardness, and a method for manufacturing the same. The hot stamped part is formed by performing hot stamping using an iron-based alloy, and includes a reinforced portion formed to have a martensite structure, a softened portion formed to have ferrite and bainite structures, and a transition portion formed between the reinforced portion and the softened portion. The reinforced portion, the transition portion and the softened portion are formed in the thickness direction of the hot stamped part.

Abstract: The present invention relates to a torsional severe plastic deformation method for a metal bar to which surface polishing is applied to the metal bar to improve the mechanical properties of the metal bar. According to an embodiment of the present invention, there is provided a torsional severe plastic deformation method for a metal bar, which includes: applying torsion to a metal bar; and removing a surface defect on the surface of the metal bar, the surface defect being caused by the applying of torsion, wherein the removing of the surface defect is carried out in a continuous manner in which the removing of the surface defect is performed together with the applying of torsion or in a discontinuous manner in which the applying of torsion is temporarily stopped and then the applying of torsion is performed, and the removing of a surface defect increases the amount of torsional rotation or the shear strain applied to the metal bar.

Abstract: A method according to the present invention, it is possible to accurately measure the stretch-flangeability of sheet metal materials without size effects even when a small amount of specimen is used, compared with the stretch-flangeability established as an international standard, and to measure the stretch-flangeability in the local region.