Steel wire material and method for manufacturing same

Abstract

This steel wire material contains 0.05%-1.2% C (“%” means “% by mass,” same hereinafter for chemical components.), 0.01%-0.7% Si, 0.1%-1.5% Mn, 0.02% max. P (not including 0%), 0.02% max. S (not including 0%), and 0.005% max. N (not including 0%), with the remainder being iron and unavoidable impurities. The steel wire material has a scale 6.0-20 μm thick and holes of an equivalent circle diameter of 1 μm max. in said scale that occupy 10% by area max. Said scale does not detach in the cooling process after hot rolling or during storage or transportation but can readily detach during mechanical descaling.

1 . A steel wire material, comprising:
 C in a content by mass of from 0.05 to 1.2%;   Si in a content by mass of from 0.01 to 0.7%;   Mn in a content by mass of from 0.1 to 1.5%;   P in a content by mass of greater than 0% and no more than 0.02%;   S in a content by mass of greater than 0% and no more than 0.02%;   N in a content by mass of greater than 0% and no more than 0.005%; and   a remainder of iron and unavoidable impurities,   wherein a scale on a surface of the wire material has a thickness of 6.0 μm or more and 20 μm or less, and   holes of an equivalent circle diameter of 1 μm or less are 10% or less by area of the scale.   
     
     
         2 . The steel wire material according to  claim 1 , further comprising Cr in a content by mass of greater than 0% and no more than 0.3%, Ni in a content by mass of greater than 0% and no more than 0.3%, or both. 
     
     
         3 . The steel wire material according to  claim 1 , further comprising Cu in a content by mass of greater than 0% and no more than 0.3%. 
     
     
         4 . The steel wire material according to  claim 1 , further comprising at least one element selected from a group consisting of Nb, V, Ti, Hf, and Zr in a content by mass of greater than 0% and no more than 0.1% in total. 
     
     
         5 . The steel wire material according to  claim 1 , further comprising Al in a content by mass of greater than 0% and no more than 0.1%. 
     
     
         6 . The steel wire material according to  claim 1 , further comprising B in a content by mass of greater than 0% and no more than 0.005%. 
     
     
         7 . The steel wire material according to  claim 1 , further comprising Ca in a content by mass of greater than 0% and no more than 0.01%, Mg in a content by mass of greater than 0% and no more than 0.01%, or both. 
     
     
         8 . A method for manufacturing a steel wire material, the method comprising:
 hot rolling steel of a chemical composition at a rolling finish temperature of from 1,000 to 1,100° C., thereby obtaining a hot rolled steel;   cooling the hot rolled steel by contacting a non-oxygen medium with the hot rolled steel, thereby obtaining a cooled steel; and   winding the cooled steel at a winding temperature of from 750 to 950° C.,   wherein, in the cooling from the rolling finish temperature to the winding temperature, a residence time at a temperature of 950° C. or above is from 0.20 to 20 s and a residence time at a temperature of 950° C. or below is less than 0.15 s, and   the chemical composition comprises C in a content by mass of from 0.05 to 1.2%, Si in a content by mass of from 0.01 to 0.7%, Mn in a content by mass of from 0.1 to 1.5%, P in a content by mass of greater than 0% and no more than 0.02%, S in a content by mass of greater than 0% and no more than 0.02%, N in a content by mass of greater than 0% and no more than 0.005%, and a remainder of iron and unavoidable impurities.   
     
     
         9 . The method according to  claim 8 , wherein the non-oxygen medium is an inert gas or water. 
     
     
         10 . The method according to  claim 9 , wherein the non-oxygen medium is nitrogen, as an inert gas.