HIGH-STRENGTH PC STEEL WIRE

摘要

The chemical composition of this high-strength PC steel wire comprises, in mass%, C: 0.90-1.10%, Si: 0.80-1.50%, Mn: 0.30-0.70%, P: 0.030% or less, S: 0.030% or less, Al: 0.010-0.070%, N: 0.0010-0.010%, Cr: 0-0.50%, V: 0-0.10%, B: 0-0.005%, Ni: 0-1.0%, Cu: 0-0.50%, and the remainder is Fe and impurities. The ratio of the Vickers hardness (HvS) of the area 0.1D [D: diameter of steel wire] from the surface of the steel wire (the surface layer) and the Vickers hardness (HvI) of the area interior to the surface layer satisfies [1.10 < HvS/HvI ≦ 1.15]. The metal composition of the region from the surface of the steel wire up to 0.01D (the outermost layer) is, by area%, a pearlite structure: less than 80%, and the remainder is a ferrite structure and/or a bainite structure; the metal structure in the region interior to the aforementioned outermost layer region is, by area%, a pearlite structure: greater than or equal to 95%, and has a tensile strength of 2000-2400 MPa. This high-strength PC steel wire has a simple manufacturing method and has excellent delayed fracture resistance.