Steel wire and spring

Abstract

A steel wire is composed of a steel containing: not less than 0.5 mass % and not more than 0.7 mass % carbon, not less than 1 mass % and not more than 2.5 mass % silicon, not less than 0.3 mass % and not more than 1 mass % manganese, and not less than 0.5 mass % and not more than 2 mass % chromium, with the balance being iron and unavoidable impurities. The steel wire has a wire diameter of not less than 0.5 mm and not more than 2 mm, and a tensile strength of not less than 2000 N/mm 2 and not more than 2700 N/mm 2 . The steel has a pearlite structure. A value obtained by dividing a sum of 5.8885×10 −3 and a lattice strain S of the steel by the tensile strength T, (S+5.8885×10 −3 )/T, the tensile strength T being in N/mm 2 , is not less than 4.8×10 −6 .

1 . A steel wire composed of a steel containing:
 not less than 0.5 mass % and not more than 0.7 mass % carbon,   not less than 1 mass % and not more than 2.5 mass % silicon,   not less than 0.3 mass % and not more than 1 mass % manganese, and   not less than 0.5 mass % and not more than 2 mass % chromium,   with the balance being iron and unavoidable impurities;   the steel wire having a wire diameter of not less than 0.5 mm and not more than 2 mm,   the steel wire having a tensile strength of not less than 2000 N/mm 2  and not more than 2700 N/mm 2 ,   the steel having a pearlite structure,   a value obtained by dividing a sum of 5.8885×10 −3  and a lattice strain S of the steel by the tensile strength T, (S+5.8885×10 −3 )/T, where the tensile strength T is in N/mm 2 , being not less than 4.8×10 −6 .   
     
     
         2 . The steel wire according to  claim 1 , wherein said (S+5.8885×10 −3 )/T is not less than 4.84×10 −6 . 
     
     
         3 . The steel wire according to  claim 1 , wherein the steel has a ferrite structure with a percentage of 20% or less. 
     
     
         4 . The steel wire according to  claim 1 , wherein the steel has a ferrite structure with a percentage of 15% or less. 
     
     
         5 . The steel wire according to  claim 1 , wherein the steel has the pearlite structure with a percentage of 80% or more. 
     
     
         6 . The steel wire according to  claim 1 , wherein the steel further contains at least one element selected from the group consisting of: not less than 0.05 mass % and not more than 0.5 mass % vanadium, not less than 0.02 mass % and not more than 1 mass % cobalt, not less than 0.02 mass % and not more than 1 mass % nickel, and not less than 0.05 mass % and not more than 0.5 mass % molybdenum. 
     
     
         7 . A spring composed of the steel wire according to  claim 1 . 
     
     
         8 . A steel wire composed of a steel containing:
 not less than 0.5 mass % and not more than 0.7 mass % carbon,   not less than 1 mass % and not more than 2.5 mass % silicon,   not less than 0.3 mass % and not more than 1 mass % manganese, and   not less than 0.5 mass % and not more than 2 mass % chromium,   with the balance being iron and unavoidable impurities;   the steel wire having a wire diameter of not less than 0.5 mm and not more than 2 mm,   the steel wire having a tensile strength of not less than 2000 N/mm 2  and not more than 2700 N/mm 2 ,   the steel having a pearlite structure,   a value obtained by dividing a sum of 5.8885×10 −3  and a lattice strain S of the steel by the tensile strength T, (S+5.8885×10 −3 )/T, where the tensile strength T is in N/mm 2 , being not less than 4.8×10 −6 ,   the steel having a ferrite structure with a percentage of 15% or less,   the steel having the pearlite structure with a percentage of 80% or more.   
     
     
         9 . A spring composed of the steel wire according to  claim 8 .