| 摘要 |
In a steel sheet, an A value is 4.5% or less, a Pcm value is 0.25% or less, a yield strength is 460 N/mm 2 to 580 N/mm 2 , a tensile strength is 550 N/mm 2 to 670 N/mm2, a difference between a hardness at 1/8t, which is a 1/8 thickness position from a surface of the steel plate in a through-thickness direction, and a hardness at 1/2t, which is a 1/2 thickness position from the surface of the steel plate in the through-thickness direction, is 20 or less by Vickers hardness, and an average grain size at 1/8t is 35 µm or less. |
