Wire rod for steel wire, and steel wire

Abstract

An object of the present invention is to provide a wire rod for a steel wire, which is excellent in low cycle fatigue characteristics and is useful as a material for a high-strength steel wire such as a wire rope or a PC steel wire, and to provide a steel wire that can exhibit such characteristics. A wire rod for a steel wire of the present invention comprises by mass: C: 0.70 to 1.3%; Si: 0.1 to 1.5%; Mn: 0.1 to 1.5%; N: 0.001 to 0.006%; Al: 0.001 to 0.10%; Ti: 0.02 to 0.20%; B: 0.0005 to 0.010%; P: 0% or more and 0.030% or less; and S: 0% or more and 0.030% or less, with the balance being iron and inevitable impurities, wherein, the wire rod having pearlite as a main phase and a hydrogen diffusion coefficient D in steel at 300° C. satisfies formula (1) below: D ≦2.5×10 −7 (cm 2 /sec)  (1).

1 . A wire rod for a steel wire, comprising by mass:
 C: 0.70 to 1.3%;   Si: 0.1 to 1.5%;   Mn: 0.1 to 1.5%;   N: 0.001 to 0.006%;   Al: 0.001 to 0.10%;   Ti: 0.02 to 0.20%;   B: 0.0005 to 0.010%;   P: 0% or more and 0.030% or less; and   S: 0% or more and 0.030% or less, with the balance being iron and inevitable impurities, wherein,   the wire rod has pearlite as a main phase, and   a hydrogen diffusion coefficient D in steel at 300° C. satisfies formula (1) below:
     D≦ 2.5×10 −7 (cm 2 /sec)  (1).
 
   
     
     
         2 . The wire rod for a steel wire according to  claim 1 , further comprising at least one selected from the group consisting of (a) to (d) below by mass:
 (a) at least one of Cr: more than 0% and 1.0% or less, and V: more than 0% and 0.5% or less;   (b) at least one of Ni: more than 0% and 0.5% or less, and Nb: more than 0% and 0.5% or less;   (c) Co: more than 0% and 1.0% or less; and   (d) at least one of Mo: more than 0% and 0.5% or less, and Cu: more than 0% and 0.5% or less.   
     
     
         3 . A steel wire comprising the chemical composition according to  claim 1 , wherein a hydrogen diffusion coefficient D in steel at 300° C. satisfies formula (1) below:
     D≦ 2.5×10 −7 (cm 2 /sec)  (1).
 
 
     
     
         4 . A steel wire comprising the chemical composition according to  claim 2 , wherein a hydrogen diffusion coefficient D in steel at 300° C. satisfies formula (1) below:
     D≦ 2.5×10 −7 (cm 2 /sec)  (1).