A wire for manufacturing steel wire for pearlitic structure bolt having a tensile strength of 950 to 1600 MPa, a steel wire for pearlitic structure bolt having a tensile strength of 950 to 1600 MPa, a pearlitic structure bolt, and a manufacturing method thereof

摘要

A wire rod having a tensile strength of 950 to 1600 MPa for manufacturing a steel wire for a pearlite structure bolt according to the present invention includes a predetermined chemical composition and is manufactured by hot rolling and then direct isothermal transformation treating, in which when an amount of C in terms of mass % is indicated as C, a structure at an area from a surface of the wire rod to a depth of 4.5 mm includes 140×C area % or more of a pearlite structure, the average block size of a pearlite block at the area from the surface of the wire rod to the depth of 4.5 mm is 20 m or less, in which the average block size is measured in a transverse section of the wire rod, and the average lamellar spacing of the pearlite structure at the area from the surface of the wire rod to the depth of 4.5 mm is more than 120 nm to 200 nm.