| 摘要 |
A wire rod contains C, Si, Mn, N, Al, P, and S in predetermined contents with the remainder being iron and inevitable impurities. The Al and N contents meet a condition specified by Expression (1) as follows: [Al]‰¤-2.1×10×[N]+0.255 (1), where [Al] and [N] are contents (in mass percent) of Al and N, respectively. The wire rod has a microstructure including 95 percent by area or more of a pearlite. The wire rod has an AlN content of 0.005% or more and a percentage of AlN particles having a diameter d GM of 10 to 20 µm of 50% or more (in number percent) in an extreme value distribution of maximum values of the diameters d GM of AlN particles, where the d GM refers to a geometrical mean (ab) 1/2 of a length "a" and a thickness "b" of an AlN particle. The wire rod is usable typically for a high-strength prestressing steel wire and wire rope that less suffer from reduction in delayed fracture resistance with an increasing strength and have delayed fracture resistance conforming building standards. |
