Wire rod

Abstract

A wire rod according to an aspect of the present invention includes a chemical composition within a predetermined range; in which an average value of % Mn+2 x % Cr over an entirety of the wire rod is 0.50% to 1.00%; 90% or more of a metallographic structure is pearlite by area fraction, and the area fraction of the cementite is less than 3%; a maximum grain size of TiN is less than 15 μm; a maximum value of % Mn+2 x % Cr in a region where both a S content and an 0 content are less than 1% in a central portion is 2.0 times or less than the average value of % Mn+2x % Cr over the entirety of the wire rod, and a ratio of the maximum value to a minimum value of % Mn+2x % Cr in a region where both a S content and an 0 content are less than 1% in an outer circumferential portion is 2.0 or less.

1 . A wire rod comprising, as a chemical composition, by mass %:
 C: 0.90% to 1.20%;   Si: 0.10% to 1.00%;   Mn: 0.20% to 0.80%;   Cr: 0.10% to 0.40%;   Al: 0% to 0.002%;   Ti: 0% to 0.002%;   N: 0% to 0.0050%;   P: 0% to 0.020%;   S: 0% to 0.010%;   O: 0% to 0.0040%;   Mo: 0% to 0.20%;   B: 0% to 0.0030%; and   a remainder including Fe and impurities,   wherein an average value of % Mn+2x % Cr over an entirety of the wire rod is 0.50% to 1.00%;   wherein 90% or more of a metallographic structure is pearlite by area fraction, and a remainder of the metallographic structure includes one or more of ferrite, cementite, and bainite, and   the area fraction of the cementite is less than 3%;   wherein a maximum grain size of TiN is less than 15 μm;   wherein a maximum value of % Mn+2x % Cr measured on a cutting surface having a right angle to a longitudinal direction of the wire rod in a region where both a S content and an O content are less than 1% in a central portion, which is a region from a central axis of the wire rod to 1/10 of a diameter of the wire rod, is 2.0 times or less than the average value of % Mn+2x % Cr over the entirety of the wire rod,   a ratio of % Mn+2x % Cr measured on the cutting surface having the right angle to the longitudinal direction of the wire rod of the maximum value to a minimum value in a region where both a S content and an O content are less than 1% in an outer circumferential portion, which is a region from an outer edge of the central portion to a depth of 0.1 mm from a surface of the wire rod, is 2.0 or less, and   % Mn and % Cr indicate the amounts of Mn and Cr by mass %.   
     
     
         2 . The wire rod according to  claim 1  comprising, as the chemical composition, by mass %:
 one or more of 
 Mo: 0.02% to 0.20%; and 
 B: 0.0003% to 0.0030%.