Steel Member And Steel Sheet

Abstract: This steel member has a predetermined chemical composition and has the following configuration. When, in the direction of member thickness and from the surface, a range from a position 1/8 the thickness to a position 3/8 the thickness, the range being centered on a position 1/4 the thickness, is defined as a 1/4 depth position, and when, regarding the grain boundaries of crystal grains having a body-centered structure and being located at the 1/4 depth position, the lengths of grain boundaries with rotation angles of 49° to 56°, where the rotation axis is in the <011> direction, are taken to be L49-56°, the lengths of grain boundaries with a rotation angles of 64° to 72° are taken to be L64-72°, the lengths of grain boundaries with rotation angles of 57° to 63° are taken to be L57-63°, and the lengths of grain boundaries with rotation angles of 4° to 12° are taken to be L4-12°, the ratio of the sum of L49-56° and L64-72° to the sum of L57-63° and L4-12° (L49-56° + L64-72°)/(L57-63° + L4-12°) is 1.40 or more. Furthermore, the tensile strength of the steel member exceeds 1500 MPa.

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