| 摘要 |
A wire material used for manufacturing a non-heat treated component whose tensile strength is 900 MPa to 1300 MPa, containing, in mass %: C: 0.20% to 0.50%, Si: 0.05% to 2.0%, Mn: 0.20% to 1.0%, being limited to contain P: 0.030% or less, S: 0.030% or less, N: 0.005% or less, F1 defined by the following expression (1) is less than 0.60, with the balance made up of Fe and inevitable impurities, wherein a metal structure contains a pearlite structure of 64×(C %)+52% or more in a volume fraction, with the balance made up of one kind or two kinds of a pro-eutectoid ferrite structure and a bainite structure, an average block grain diameter of the pearlite structure at a region from a surface layer to 0.1 D is 15 μm or less when a diameter of the wire material is set to be D, and (the average block grain diameter of the pearlite structure at the region from the surface layer to 0.1 D)/(an average block grain diameter of the pearlite structure at a range from 0.25 D to a center) is less than 1.0. F1=C(%)+Si(%)/24+Mn(%)/6   (1) |
