| 摘要 |
Provided is a carbon steel wire with unprecedentedly high strength and excellent ductility and fatigue resistance, a process for producing the same, and a method of evaluating the same is provided. Provided is a carbon steel wire having a carbon content of 0.50 to 1.10% by mass, wherein the ratio of the hardness of the surface layer portion 13 on a cross section 12 and the hardness of the surface layer portion 3 on a longitudinal section 2, a coefficient X (cross sectional hardness/longitudinal sectional hardness), and the ratio of the hardness of the center portion 14 on the cross section 12 and the hardness of the center portion 4 on the longitudinal section 2, a coefficient X (cross sectional hardness/longitudinal sectional hardness), each satisfy a relationship represented by the following expression: 0.9<coefficient X≰1.10, and wherein the carbon steel wire has a tensile strength of 4000 MPa or higher.
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