Steel wire rod for hard drawn spring drawn wire rod for hard drawn spring and hard drawn spring and method for producing hard drawn spring

摘要

Wherein the steel sheet contains each of C: less than 0.5 to 0.7 mass%, Si: 1.4 to 2.5 mass%, Mn: 0.5 to 1.5 mass%, Cr: 0.05 to 2.0 mass% and V: 0.05 to 0.40 mass% Rp satisfies the following formula (1), a steel wire rod for a spring for a cushion spring exhibiting fatigue strength and permanent permanent deformation equal to or higher than that of a spring using an oil fattening line is disclosed.;Rp (area%) 55 [C] + 61 (1);Note that [C] represents the content of C (% by mass).