Steel Member And Steel Sheet

Abstract: This steel member has a specific chemical composition, and if a range that is centered on the position corresponding to 1/4 the thickness from the surface in the thickness direction, and extends from the position corresponding to 1/8 the thickness to the position corresponding to 3/8 the thickness from the surface in the thickness direction is taken as the 1/4 depth position, and among the grain boundaries of crystal grains each having a body-centered structure at the 1/4 depth position, if L49-56° is the length of a grain boundary having a rotation angle of 49° to 56°, L64-72° is the length of a grain boundary having a rotation angle of 64° to 72°, L57-63° is the length of a grain boundary having a rotation angle of 57° to 63° and L4-12° is the length of a grain boundary having a rotation angle of 4° to 12° as measured using the <011> direction as the rotation axis, the ratio of the sum of L49-56° and L64-72° to the sum of L57-63° and L4-12°, that is (L49-56° + L64-72°)/(L57-63° + L4-12°), is 1.30 or more. This steel member has a tensile strength of more than 1,500 MPa.

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