Patent ID: 7074282

Claim:
A steel wire rod for hard-drawn springs which contains carbon in a range from 0.5 to less than 0.7 mass %, silicon in a range from 1.4 to 2.5 mass %, manganese in a range from 0.5 to 1.5 mass %, chromium in a range from 0.05 to 2.0 mass %, and vanadium in a range from 0.05 to 0.40 mass %, and has an area ratio Rp with respect to pearlite which satisfies the mathematical expression (1): Rp (area %)â‰§55Ã— [C ]+61â€ƒâ€ƒ(1) where [C] denotes the content (mass %) of carbon, and wherein ferrite in lamellar in which the number of carbide and carbonitride of vanadium and chromium, complex carbide and complex carbonitride of vanadium and chromium each having a diameter of 50 nm or less in terms of a hypothetical circle, is not smaller than ten per Î¼m 2 .