Tyre bead wire and process for production thereof

Abstract

A tire bead wire and a process for producing a tire bead where a carbon steel wire rod containing carbon in a range of 0.61% or more to 0.65% or less in weight percent and having a diameter in a range of 5.5 mm to 6.5 mm is wiredrawn through a single wiredrawing process to a predetermined final wiredrawing diameter having a true strain in a range of 2.0 to 4.0 and is turned to a pearlite structure in which ferrite and cementite are drawn in parallel with a narrow interval therebetween.

1 - 5 . (canceled) 
     
     
         6 . A tire bead wire, comprising:
 carbon in a range of 0.61% or more to 0.65% or less in weight percent; and   a pearlite structure comprising ferrite and cementite,   wherein the bead wire has a final diameter,   wherein the bead wire has a true strain in a range of 2.0 to 4.0,   wherein the ferrite and cementite have a narrow interval therebetween.   
     
     
         7 . The bead wire of  claim 6 , wherein the bead wire has a final diameter in a range of 0.94 to 2.20 mm. 
     
     
         8 . The bead wire of  claim 6 , wherein the bead wire has a final diameter in a range of 0.94 to 1.30 mm. 
     
     
         9 . The bead wire of  claim 6 , wherein the bead wire has a final diameter in a range of 1.5 to 2.20 mm. 
     
     
         10 . The bead wire of  claim 6 , further comprising Si. 
     
     
         11 . The bead wire of  claim 6 , further comprising Mn. 
     
     
         12 . The bead wire of  claim 6 , further comprising Si and Mn. 
     
     
         13 . The bead wire of  claim 6 , wherein the bead wire comprises carbon in a range of 0.61% or more to 0.63% or less in weight percent. 
     
     
         14 . The bead wire of  claim 6 , wherein the bead wire comprises carbon in a range of 0.63% or more to 0.65% or less in weight percent. 
     
     
         15 . A process for producing a tire bead wire, the process comprising:
 (a) wiredrawing, only once, a carbon steel wire rod comprising carbon in a range of 0.61% or more to 0.65% or less in weight percent and having an initial diameter in a range of 5.5 mm to 6.5 mm, to obtain a tire bead wire having a final diameter less than the initial diameter and a true strain in a range of 2.0 to 4.0; then   (b) bluing the tire bead wire; and, after the bluing,   (c) plating the tire bead wire.   
     
     
         16 . The process of  claim 15 , wherein, after the wiredrawing (a), the bead wire has a final diameter in a range of 0.94 to 2.20 mm. 
     
     
         17 . The process of  claim 15 , wherein the carbon steel wire rod has an initial diameter of 5.5 mm and, after the wiredrawing (a), the bead wire has a final diameter in a range of 0.94 to 1.30 mm. 
     
     
         18 . The process of  claim 15 , wherein the carbon steel wire rod has an initial diameter of 6.5 mm and, after the wiredrawing (a), the bead wire has a final diameter in a range of 1.5 to 2.20 mm. 
     
     
         19 . The process of  claim 15 , wherein the carbon steel wire rod further comprises Si. 
     
     
         20 . The process of  claim 15 , wherein the carbon steel wire rod further comprises Mn. 
     
     
         21 . The process of  claim 15 , wherein the carbon steel wire rod further comprises Si and Mn. 
     
     
         22 . The process of  claim 15 , wherein the carbon steel wire rod comprises carbon in a range of 0.61% or more to 0.63% or less in weight percent. 
     
     
         23 . The process of  claim 15 , wherein the carbon steel wire rod comprises carbon in a range of 0.63% or more to 0.65% or less in weight percent. 
     
     
         24 . A tire bead wire obtained by the process of  claim 15 .